Chemistry › Organic Chemistry

Free Radicals and Antioxidants

Works Count: 48517

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Description

This cluster of papers focuses on predicting the antioxidant activity of phenolic compounds through theoretical methods, DFT calculations, and analysis of radical scavenging mechanisms. It explores the effects of solvents, reaction kinetics, and redox potentials in the context of oxidative stress and free radicals.

Keywords

Antioxidant; Phenolic Compounds; Radical Scavenging; DFT Calculations; Oxidative Stress; Free Radicals; Hydrogen Atom Transfer; Solvent Effects; Reaction Kinetics; Redox Potentials

[36] Flavonoids as antioxidants: Determination of radical-scavenging efficiencies

1990-01-01

Wolf Bors , Werner Heller , Christa Michel +1 more

[1] Role of free radicals and catalytic metal ions in human disease: An overview

1990-01-01

Barry Halliwell , John M.C. Gutteridge

Targeting cancer cells by ROS-mediated mechanisms: a radical therapeutic approach?

2009-05-29

Dunyaporn Trachootham , Jérôme Alexandre , Peng Huang

The role of antioxidants in the chemistry of oxidative stress: A review

2015-04-22

Aurelia Magdalena Pisoschi , Aneta Pop

Antioxidant and radical scavenging properties of curcumin

2008-05-08

Tuba Parlak Ak , İlhami Gülçın

Oxidative stress: a concept in redox biology and medicine

2015-01-03

Helmut Sies

"Oxidative stress" as a concept in redox biology and medicine has been formulated in 1985; at the beginning of 2015, approx. 138,000 PubMed entries show for this term. This concept … "Oxidative stress" as a concept in redox biology and medicine has been formulated in 1985; at the beginning of 2015, approx. 138,000 PubMed entries show for this term. This concept has its merits and its pitfalls. Among the merits is the notion, elicited by the combined two terms of (i) aerobic metabolism as a steady-state redox balance and (ii) the associated potential strains in the balance as denoted by the term, stress, evoking biological stress responses. Current research on molecular redox switches governing oxidative stress responses is in full bloom. The fundamental importance of linking redox shifts to phosphorylation/dephosphorylation signaling is being more fully appreciated, thanks to major advances in methodology. Among the pitfalls is the fact that the underlying molecular details are to be worked out in each particular case, which is bvious for a global concept, but which is sometimes overlooked. This can lead to indiscriminate use of the term, oxidative stress, without clear relation to redox chemistry. The major role in antioxidant defense is fulfilled by antioxidant enzymes, not by small-molecule antioxidant compounds. The field of oxidative stress research embraces chemistry, biochemistry, cell biology, physiology and pathophysiology, all the way to medicine and health and disease research.

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A procedure to measure the antiradical efficiency of polyphenols

1998-02-01

Concepción Sánchez‐Moreno , José A. Larrauri , Fulgêncio Saura-Calixto

The kinetic behaviour of polyphenols common in fruits as free radical scavengers was studied using 2,2-diphenyl-1-picrylhydrazyl (DPPH•). After addi-tion of different standard concentrations to DPPH· (0·025 g litre−1), the percentage … The kinetic behaviour of polyphenols common in fruits as free radical scavengers was studied using 2,2-diphenyl-1-picrylhydrazyl (DPPH•). After addi-tion of different standard concentrations to DPPH· (0·025 g litre−1), the percentage of remaining DPPH• was determined at different times from the absorbances at 515 nm. The percentage remaining DPPH• against reaction time followed a multiplicative model equation: ln [DPPHREM•]=b ln t+ln a. The slopes of these equations may be useful parameters to define the antioxidant capacity. The steeper the slope, the lower the amount of antioxidant necessary to decrease by 50% the initial DPPH• concentration (EC50). This parameter, EC50, is widely used to measure antioxidant power, but it does not takes into account the reaction time. Time needed to reach the steady state to the concentration corresponding at EC50 (TEC50) was calculated, and antiradical efficiency (AE) was proposed as a new parameter to characterise the antioxidant compounds where AE=1/EC50 TEC50. It was shown that AE is more discriminatory than EC50. AE values are more useful because they also take into account the reaction time. The results have shown that the order of the AE (×10−3) in the compounds tested was: ascorbic acid (11·44)>caffeic acid (2·75)⩾gallic acid (2·62)>tannic acid (0·57)⩾DL-α-tocopherol (0·52)>rutin (0·21)⩾quercetin (0·19)>ferulic acid (0·12)⩾3-tert-butyl-4-hydroxyanisole, BHA (0·10)>resveratrol (0·05). © 1998 SCI.

Action of Phenolic Derivatives (Acetaminophen, Salicylate, and 5-Aminosalicylate) as Inhibitors of Membrane Lipid Peroxidation and as Peroxyl Radical Scavengers

1994-11-01

Teresa C.P. Dinis , Vı́tor M.C. Madeira , Leonor M. Almeida

Review on in vivo and in vitro methods evaluation of antioxidant activity

2012-06-15

Md Nur Alam , Nusrat Jahan Bristi , Md Rafiquzzaman

A good number of abstracts and research articles (in total 74) published, so far, for evaluating antioxidant activity of various samples of research interest were gone through where 407 methods … A good number of abstracts and research articles (in total 74) published, so far, for evaluating antioxidant activity of various samples of research interest were gone through where 407 methods were come across, which were repeated from 29 different methods. These were classified as in vitro and in vivo methods. And those are described and discussed below in this review article. In the later part of this review article, frequency of in vitro as well as in vivo methods is analyzed with a bar diagram. Solvents are important for extracting antioxidants from natural sources. Frequency of solvents used for extraction is also portrayed and the results are discussed in this article. As per this review there are 19 in vitro methods and 10 in vivo methods that are being used for the evaluation of antioxidant activity of the sample of interest. DPPH method was found to be used mostly for the in vitro antioxidant activity evaluation purpose while LPO was found as mostly used in vivo antioxidant assay. Ethanol was with the highest frequency as solvent for extraction purpose.

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The Chemistry behind Antioxidant Capacity Assays

2005-02-25

Dejian Huang , Boxin Ou , Ronald L. Prior

This review summarizes the multifaceted aspects of antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Depending upon the reactions involved, … This review summarizes the multifaceted aspects of antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Depending upon the reactions involved, these assays can roughly be classified into two types: assays based on hydrogen atom transfer (HAT) reactions and assays based on electron transfer (ET). The majority of HAT-based assays apply a competitive reaction scheme, in which antioxidant and substrate compete for thermally generated peroxyl radicals through the decomposition of azo compounds. These assays include inhibition of induced low-density lipoprotein autoxidation, oxygen radical absorbance capacity (ORAC), total radical trapping antioxidant parameter (TRAP), and crocin bleaching assays. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes color when reduced. The degree of color change is correlated with the sample's antioxidant concentrations. ET-based assays include the total phenols assay by Folin−Ciocalteu reagent (FCR), Trolox equivalence antioxidant capacity (TEAC), ferric ion reducing antioxidant power (FRAP), "total antioxidant potential" assay using a Cu(II) complex as an oxidant, and DPPH. In addition, other assays intended to measure a sample's scavenging capacity of biologically relevant oxidants such as singlet oxygen, superoxide anion, peroxynitrite, and hydroxyl radical are also summarized. On the basis of this analysis, it is suggested that the total phenols assay by FCR be used to quantify an antioxidant's reducing capacity and the ORAC assay to quantify peroxyl radical scavenging capacity. To comprehensively study different aspects of antioxidants, validated and specific assays are needed in addition to these two commonly accepted assays. Keywords: Antioxidants; assay; hydrogen atom transfer reaction; electron-transfer reaction; free radicals; oxidants

Systematic optimization of long-range corrected hybrid density functionals

2008-02-27

Jeng‐Da Chai , Martin Head‐Gordon

A general scheme for systematically modeling long-range corrected (LC) hybrid density functionals is proposed. Our resulting two LC hybrid functionals are shown to be accurate in thermochemistry, kinetics, and noncovalent … A general scheme for systematically modeling long-range corrected (LC) hybrid density functionals is proposed. Our resulting two LC hybrid functionals are shown to be accurate in thermochemistry, kinetics, and noncovalent interactions, when compared with common hybrid density functionals. The qualitative failures of the commonly used hybrid density functionals in some “difficult problems,” such as dissociation of symmetric radical cations and long-range charge-transfer excitations, are significantly reduced by the present LC hybrid density functionals.

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A novel automated direct measurement method for total antioxidant capacity using a new generation, more stable ABTS radical cation

2004-03-06

Özcan Erel

Predicting the Activity of Phenolic Antioxidants: Theoretical Method, Analysis of Substituent Effects, and Application to Major Families of Antioxidants

2001-01-23

James S. Wright , Erin R. Johnson , Gino A. DiLabio

A procedure based on density functional theory is used for the calculation of the gas-phase bond dissociation enthalpy (BDE) and ionization potential for molecules belonging to the class of phenolic … A procedure based on density functional theory is used for the calculation of the gas-phase bond dissociation enthalpy (BDE) and ionization potential for molecules belonging to the class of phenolic antioxidants. We show that use of locally dense basis sets (LDBS) vs full basis sets gives very similar results for monosubstituted phenols, and that the LDBS procedure gives good agreement with the change in experimental BDE values for highly substituted phenols in benzene solvent. Procedures for estimating the O−H BDE based on group additivity rules are given and tested. Several interesting classes of phenolic antioxidants are studied with these methods, including commercial antioxidants used as food additives, compounds related to Vitamin E, flavonoids in tea, aminophenols, stilbenes related to resveratrol, and sterically hindered phenols. On the basis of these results we are able to interpret relative rates for the reaction of antioxidants with free radicals, including a comparison of both H-atom-transfer and single-electron-transfer mechanisms, and conclude that in most cases H-atom transfer will be dominant.

Antioxidant activity applying an improved ABTS radical cation decolorization assay

1999-05-01

Roberta Re , Nicoletta Pellegrini , Anna R. Proteggente +3 more

Free Radicals: Properties, Sources, Targets, and Their Implication in Various Diseases

2014-07-14

Phaniendra Alugoju , Dinesh Babu Jestadi , Latha Periyasamy

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Oxygen-radical absorbance capacity assay for antioxidants

1993-03-01

Guohua Cao , Helaine M. Alessio , Richard G. Cutler

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The solvatochromic comparison method. 6. The .pi.* scale of solvent polarities

1977-08-01

Mortimer J. Kamlet , J.‐L. M. Abboud , R. W. TAFT

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe solvatochromic comparison method. 6. The .pi.* scale of solvent polaritiesMortimer J. Kamlet, Jose Luis Abboud, and R. W. TaftCite this: J. Am. Chem. Soc. 1977, 99, … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe solvatochromic comparison method. 6. The .pi.* scale of solvent polaritiesMortimer J. Kamlet, Jose Luis Abboud, and R. W. TaftCite this: J. Am. Chem. Soc. 1977, 99, 18, 6027–6038Publication Date (Print):August 1, 1977Publication History Published online1 May 2002Published inissue 1 August 1977https://pubs.acs.org/doi/10.1021/ja00460a031https://doi.org/10.1021/ja00460a031research-articleACS PublicationsRequest reuse permissionsArticle Views4808Altmetric-Citations1422LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

β-Carotene: an Unusual Type of Lipid Antioxidant

1984-05-11

Graham W. Burton , K. U. Ingold

The mechanism of lipid peroxidation and the manner in which antioxidants function is reviewed. β-Carotene is a purported anticancer agent, which is believed by some to have antioxidant action of … The mechanism of lipid peroxidation and the manner in which antioxidants function is reviewed. β-Carotene is a purported anticancer agent, which is believed by some to have antioxidant action of a radical-trapping type. However, definitive experimental support for such action has been lacking. New experiments in vitro show that β-carotene belongs to a previously unknown class of biological antioxidants. Specifically, it exhibits good radical-trapping antioxidant behavior only at partial pressures of oxygen significantly less than 150 torr, the pressure of oxygen in normal air. Such low oxygen partial pressures are found in most tissues under physiological conditions. At higher oxygen pressures, β-carotene loses its antioxidant activity and shows an autocatalytic, prooxidant effect, particularly at relatively high concentrations. Similar oxygen-pressure-dependent behavior may be shown by other compounds containing many conjugated double bonds.

Free radicals, natural antioxidants, and their reaction mechanisms

2015-01-01

Satish Balasaheb Nimse , Dilipkumar Pal

The normal biochemical reactions in our body, increased exposure to the environment, and higher levels of dietary xenobiotic's result in the generation of reactive oxygen species (ROS) and reactive nitrogen … The normal biochemical reactions in our body, increased exposure to the environment, and higher levels of dietary xenobiotic's result in the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS).

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Free Radicals in Biology and Medicine

1990-01-01

E.T. Land

(1990). Free Radicals in Biology and Medicine. International Journal of Radiation Biology: Vol. 58, No. 4, pp. 725-725. (1990). Free Radicals in Biology and Medicine. International Journal of Radiation Biology: Vol. 58, No. 4, pp. 725-725.

Free radicals, metals and antioxidants in oxidative stress-induced cancer

2006-01-24

Marián Valko , Christopher J. Rhodes , Ján Moncóľ +2 more

Linear solvation energy relationships. 23. A comprehensive collection of the solvatochromic parameters, .pi.*, .alpha., and .beta., and some methods for simplifying the generalized solvatochromic equation

1983-08-01

Mortimer J. Kamlet , J.‐L. M. Abboud , Michael H. Abraham +1 more

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLinear solvation energy relationships. 23. A comprehensive collection of the solvatochromic parameters, .pi.*, .alpha., and .beta., and some methods for simplifying the generalized solvatochromic equationMortimer J. Kamlet, … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLinear solvation energy relationships. 23. A comprehensive collection of the solvatochromic parameters, .pi.*, .alpha., and .beta., and some methods for simplifying the generalized solvatochromic equationMortimer J. Kamlet, Jose Luis M. Abboud, Michael H. Abraham, and R. W. TaftCite this: J. Org. Chem. 1983, 48, 17, 2877–2887Publication Date (Print):August 1, 1983Publication History Published online1 May 2002Published inissue 1 August 1983https://pubs.acs.org/doi/10.1021/jo00165a018https://doi.org/10.1021/jo00165a018research-articleACS PublicationsRequest reuse permissionsArticle Views10808Altmetric-Citations3065LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Chemistry and biochemistry of 4-hydroxynonenal, malonaldehyde and related aldehydes

1991-01-01

Hermann Esterbauer , Rudolf Jörg Schaur , Helmward Zöllner

Evaluation of the probe 2',7'-dichlorofluorescin as an indicator of reactive oxygen species formation and oxidative stress

1992-03-01

Carl LeBel , Harry Ischiropoulos , Stephen C. Bondy

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEvaluation of the probe 2',7'-dichlorofluorescin as an indicator of reactive oxygen species formation and oxidative stressCarl P. LeBel, Harry Ischiropoulos, and Stephen C. BondyCite this: Chem. Res. … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEvaluation of the probe 2',7'-dichlorofluorescin as an indicator of reactive oxygen species formation and oxidative stressCarl P. LeBel, Harry Ischiropoulos, and Stephen C. BondyCite this: Chem. Res. Toxicol. 1992, 5, 2, 227–231Publication Date (Print):March 1, 1992Publication History Published online1 May 2002Published inissue 1 March 1992https://pubs.acs.org/doi/10.1021/tx00026a012https://doi.org/10.1021/tx00026a012research-articleACS PublicationsRequest reuse permissionsArticle Views6322Altmetric-Citations2169LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

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Antioxidant and Prooxidant Behavior of Flavonoids: Structure-Activity Relationships

1997-01-01

Guohua Cao , E. Sofić , Ronald L. Prior

The Pecking Order of Free Radicals and Antioxidants: Lipid Peroxidation, α-Tocopherol, and Ascorbate

1993-02-01

Garry R. Buettner

Use of a free radical method to evaluate antioxidant activity

1995-01-01

Wendy Brand-Williams , Marie‐Elisabeth Cuvelier , Claudette Berset

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Genesis and development of DPPH method of antioxidant assay

2011-02-24

Sagar B. Kedare , R. P. Singh

Standardized Methods for the Determination of Antioxidant Capacity and Phenolics in Foods and Dietary Supplements

2005-04-26

Ronald L. Prior , Xianli Wu , Karen M. Schaich

Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of … Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of each method. This overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceutical, and dietary supplement industries. From evaluation of data presented at the First International Congress on Antioxidant Methods in 2004 and in the literature, as well as consideration of potential end uses of antioxidants, it is proposed that procedures and applications for three assays be considered for standardization: the oxygen radical absorbance capacity (ORAC) assay, the Folin−Ciocalteu method, and possibly the Trolox equivalent antioxidant capacity (TEAC) assay. ORAC represent a hydrogen atom transfer (HAT) reaction mechanism, which is most relevant to human biology. The Folin−Ciocalteu method is an electron transfer (ET) based assay and gives reducing capacity, which has normally been expressed as phenolic contents. The TEAC assay represents a second ET-based method. Other assays may need to be considered in the future as more is learned about some of the other radical sources and their importance to human biology. Keywords: Standardized methods; antioxidant capacity; foods, dietary supplements; nutraceuticals; ORAC; Folin−Ciocalteu method; TEAC

Free radicals, oxidative stress, and antioxidants in human health and disease

1998-02-01

Okezie I. Aruoma

Free radicals and other reactive oxygen species (ROS) are constantly formed in the human body. Free-radical mechanisms have been implicated in the pathology of several human diseases, including cancer, atherosclerosis, … Free radicals and other reactive oxygen species (ROS) are constantly formed in the human body. Free-radical mechanisms have been implicated in the pathology of several human diseases, including cancer, atherosclerosis, malaria, and rheumatoid arthritis and neurodegenerative diseases. For example, the superoxide radical (O

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Rate Constants for Reactions of Inorganic Radicals in Aqueous Solution

1988-07-01

P. Neta , Robert E. Huie , Alberta B. Ross

Rate constants have been compiled for reactions of various inorganic radicals produced by radiolysis or photolysis, as well as by other chemical means in aqueous solutions. Data are included for … Rate constants have been compiled for reactions of various inorganic radicals produced by radiolysis or photolysis, as well as by other chemical means in aqueous solutions. Data are included for the reactions of ⋅CO2 −, CO3⋅−, O3, ⋅N3, ⋅NH2, ⋅NO2, NO3⋅, ⋅PO32−, PO4⋅2−, SO2⋅ −, ⋅SO3 −, SO4⋅−, SO5⋅−, SeO3⋅ −, (SCN)2⋅ −, CL2⋅−, Br2⋅ −, I2⋅ −, ClO2⋅, BrO2⋅, and miscellaneous related radicals, with inorganic and organic compounds.

Brownian motion in a field of force and the diffusion model of chemical reactions

1940-04-01

H. A. Kramers

Structure-antioxidant activity relationships of flavonoids and phenolic acids

1996-01-01

Catherine Rice‐Evans , Nicholas J. Miller , George Paganga

Solvatochromic Dyes as Solvent Polarity Indicators

1994-12-01

C. L. Reichardt

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolvatochromic Dyes as Solvent Polarity IndicatorsChristian ReichardtCite this: Chem. Rev. 1994, 94, 8, 2319–2358Publication Date (Print):December 1, 1994Publication History Published online1 May 2002Published inissue 1 December 1994https://pubs.acs.org/doi/10.1021/cr00032a005https://doi.org/10.1021/cr00032a005research-articleACS … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolvatochromic Dyes as Solvent Polarity IndicatorsChristian ReichardtCite this: Chem. Rev. 1994, 94, 8, 2319–2358Publication Date (Print):December 1, 1994Publication History Published online1 May 2002Published inissue 1 December 1994https://pubs.acs.org/doi/10.1021/cr00032a005https://doi.org/10.1021/cr00032a005research-articleACS PublicationsRequest reuse permissionsArticle Views28620Altmetric-Citations4564LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Development and Validation of an Improved Oxygen Radical Absorbance Capacity Assay Using Fluorescein as the Fluorescent Probe

2001-09-18

Boxin Ou , Maureen Hampsch‐Woodill , Ronald L. Prior

An improved method of oxygen radical absorbance capacity (ORAC) assay has been developed and validated using fluorescein (3',6'-dihydroxyspiro[isobenzofuran-1[3H],9'[9H]-xanthen]-3-one) as the fluorescent probe. Our results demonstrate that fluorescein (FL) is superior … An improved method of oxygen radical absorbance capacity (ORAC) assay has been developed and validated using fluorescein (3',6'-dihydroxyspiro[isobenzofuran-1[3H],9'[9H]-xanthen]-3-one) as the fluorescent probe. Our results demonstrate that fluorescein (FL) is superior to B-phycoerythrin. The oxidized FL products induced by peroxyl radical were identified by LC/MS, and the reaction mechanism was determined to follow a classic hydrogen atom transfer mechanism. In addition, methodological and mechanistic comparison of ORAC(FL) with other widely used methods was discussed. It is concluded that, unlike other popular methods, the improved ORAC(FL) assay provides a direct measure of hydrophilic chain-breaking antioxidant capacity against peroxyl radical.

Theoretical Basis, Experimental Design, and Computerized Simulation of Synergism and Antagonism in Drug Combination Studies

2006-09-01

Ting‐Chao Chou

The median-effect equation derived from the mass-action law principle at equilibrium-steady state via mathematical induction and deduction for different reaction sequences and mechanisms and different types of inhibition has been … The median-effect equation derived from the mass-action law principle at equilibrium-steady state via mathematical induction and deduction for different reaction sequences and mechanisms and different types of inhibition has been shown to be the unified theory for the Michaelis-Menten equation, Hill equation, Henderson-Hasselbalch equation, and Scatchard equation. It is shown that dose and effect are interchangeable via defined parameters. This general equation for the single drug effect has been extended to the multiple drug effect equation for n drugs. These equations provide the theoretical basis for the combination index (CI)-isobologram equation that allows quantitative determination of drug interactions, where CI < 1, = 1, and > 1 indicate synergism, additive effect, and antagonism, respectively. Based on these algorithms, computer software has been developed to allow automated simulation of synergism and antagonism at all dose or effect levels. It displays the dose-effect curve, median-effect plot, combination index plot, isobologram, dose-reduction index plot, and polygonogram for in vitro or in vivo studies. This theoretical development, experimental design, and computerized data analysis have facilitated dose-effect analysis for single drug evaluation or carcinogen and radiation risk assessment, as well as for drug or other entity combinations in a vast field of disciplines of biomedical sciences. In this review, selected examples of applications are given, and step-by-step examples of experimental designs and real data analysis are also illustrated. The merging of the mass-action law principle with mathematical induction-deduction has been proven to be a unique and effective scientific method for general theory development. The median-effect principle and its mass-action law based computer software are gaining increased applications in biomedical sciences, from how to effectively evaluate a single compound or entity to how to beneficially use multiple drugs or modalities in combination therapies.

Method for the measurement of antioxidant activity in human fluids

2001-05-01

D Koraćević

Aim —To develop a new, simple, and cheap method for estimating antioxidant activity in human fluids. Methods —The assay measured the capacity of the biological fluids to inhibit the production … Aim —To develop a new, simple, and cheap method for estimating antioxidant activity in human fluids. Methods —The assay measured the capacity of the biological fluids to inhibit the production of thiobarbituric acid reactive substances (TBARS) from sodium benzoate under the influence of the free oxygen radicals derived from Fenton's reaction. A solution of 1 mmol/litre uric acid was used as standard. Results —The following mean (SD) antioxidative activities were found (as uric acid) in the various biological fluids: serum, 2.04 (0.20) mmol/litre; urine, 176.5 (25.6) μmol/litre; cerebrospinal fluid, 95.0 (26.9) μmol/litre; aqueous humour oculi, 61.25 (9.9) μmol/litre; saliva, 838.5 (48.2) μmol/litre; tears, 247.0 (17.0) μmol/litre; ascites fluid, 270.0 (63.3) μmol/litre; kidney cyst fluid, 387.1 (28.1) μmol/litre. Small samples of the biological material were needed for the analyses: 10 μl of serum and 50–100 μl of other body fluids. In the sera of 48 healthy individuals there was a significant positive correlation between values obtained with the Randox method (as a reference method) and the new method proposed here (correlation coefficient, 0.8728; mean difference between methods, <0.4%). Conclusions —This method is easy, rapid, reliable, and practical for the routine measurement of total antioxidant activity in serum and other human body fluids. Small samples of biological material are needed for the analyses and the results are comparable with the reference (Randox) method.

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Invited Review: Oxidation of Biological Systems: Oxidative Stress Phenomena, Antioxidants, Redox Reactions, and Methods for Their Quantification

2002-10-01

Ron Kohen , Abraham Nyska

Reactive oxygen species (ROS) and other radicals are involved in a variety of biological phenomena, such as mutation, carcinogenesis, degenerative and other diseases, inflammation, aging, and development. ROS are well … Reactive oxygen species (ROS) and other radicals are involved in a variety of biological phenomena, such as mutation, carcinogenesis, degenerative and other diseases, inflammation, aging, and development. ROS are well recognized for playing a dual role as deleterious and beneficial species. The objectives of this review are to describe oxidative stress phenomena, terminology, definitions, and basic chemical characteristics of the species involved; examine the biological targets susceptible to oxidation and the defense mechanisms of the organism against these reactive metabolites; and analyze methodologies, including immunohistochemical markers, used in toxicological pathology in the visualization of oxidative stress phenomena. Direct detection of ROS and other free radicals is difficult, because these molecules are short-lived and highly reactive in a nonspecific manner. Ongoing oxidative damage is, thus, generally analyzed by measurement of secondary products including derivatives of amino acids, nuclei acids, and lipid peroxidation. Attention has been focused on electrochemical methods based on voltammetry measurements for evaluating the total reducing power of biological fluids and tissues. This approach can function as a tool to assess the antioxidant-reducing profile of a biological site and follow changes in pathological situations. This review thus includes different topics essential for understanding oxidative stress phenomena and provides tools for those intending to conduct study and research in this field.

Role of oxygen radicals in DNA damage and cancer incidence

2004-11-01

Marián Valko , Mário Izakovič , Milan Mazúr +2 more

THE USE OF THE STABLE FREE RADICAL DIPHENYLPICRYLHYDRAZYL (DPPH) FOR ESTIMATING ANTIOXIDANT ACTIVITY

2004-01-01

Philip Molyneux

Molyneux, P. The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for estimating antioxidant activity Molyneux, P. The use of the stable free radical diphenylpicrylhydrazyl (DPPH) for estimating antioxidant activity

Aging: A Theory Based on Free Radical and Radiation Chemistry

1956-07-01

Denham Harman

The phenomenon of growth, decline and death—aging—has been the source of considerable speculation (1, 8, 10). This cycle seems to be a more or less direct function of the metabolic … The phenomenon of growth, decline and death—aging—has been the source of considerable speculation (1, 8, 10). This cycle seems to be a more or less direct function of the metabolic rate and this in turn depends on the species (animal or plant) on which are superimposed the factors of heredity and the effects of the stresses and strains of life—which alter the metabolic activity. The universality of this phenomenon suggests that the reactions which cause it are basically the same in all living things. Viewing this process in the light of present day free radical and radiation chemistry and of radiobiology, it seems possible that one factor in aging may be related to deleterious side attacks of free radicals (which are normally produced in the course of cellular metabolism) on cell constituents.* Irradiation of living things induces mutation, cancer, and aging (9). Inasmuch as these also arise spontaneously in nature, it is natural to inquire if the processes might not be similar. It is believed that one mechanism of irradiation effect is through liberation of OH and HO 2 radicals (12). There is evidence, although indirect, that these two highly active free radicals are produced normally in living systems. In the first place, free radicals are present in living cells; this was recently demonstrated in vivo by a paramagnetic resonance absorption method (3). Further, it was shown that the concentration of free radicals increased with increasing metabolic activity in conformity with the postulates set forth some years ago that free radicals were involved in biologic oxidation-reduction reactions (11, 13). Are some of these free radicals OH and/or HO2, or radicals of a similar high order of reactivity, and where might they arise in the cell? The most likely source of OH and HO2 radicals, at least in the animal cell, would be the interaction of the respiratory enzymes involved

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PROPKA3: Consistent Treatment of Internal and Surface Residues in Empirical pKaPredictions

2011-01-06

Mats H. M. Olsson , Chresten R. Søndergaard , Michał Rostkowski +1 more

In this study, we have revised the rules and parameters for one of the most commonly used empirical pKa predictors, PROPKA, based on better physical description of the desolvation and … In this study, we have revised the rules and parameters for one of the most commonly used empirical pKa predictors, PROPKA, based on better physical description of the desolvation and dielectric response for the protein. We have introduced a new and consistent approach to interpolate the description between the previously distinct classifications into internal and surface residues, which otherwise is found to give rise to an erratic and discontinuous behavior. Since the goal of this study is to lay out the framework and validate the concept, it focuses on Asp and Glu residues where the protein pKa values and structures are assumed to be more reliable. The new and improved implementation is evaluated and discussed; it is found to agree better with experiment than the previous implementation (in parentheses): rmsd = 0.79 (0.91) for Asp and Glu, 0.75 (0.97) for Tyr, 0.65 (0.72) for Lys, and 1.00 (1.37) for His residues. The most significant advance, however, is in reducing the number of outliers and removing unreasonable sensitivity to small structural changes that arise from classifying residues as either internal or surface.

Spectrophotometric Study of the Reaction of Protein Sulfhydryl Groups with Organic Mercurials

1954-09-01

Paul D. Boyer

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectrophotometric Study of the Reaction of Protein Sulfhydryl Groups with Organic MercurialsP. D. BoyerCite this: J. Am. Chem. Soc. 1954, 76, 17, 4331–4337Publication Date (Print):September 1, 1954Publication … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectrophotometric Study of the Reaction of Protein Sulfhydryl Groups with Organic MercurialsP. D. BoyerCite this: J. Am. Chem. Soc. 1954, 76, 17, 4331–4337Publication Date (Print):September 1, 1954Publication History Published online1 May 2002Published inissue 1 September 1954https://pubs.acs.org/doi/10.1021/ja01646a025https://doi.org/10.1021/ja01646a025research-articleACS PublicationsRequest reuse permissionsArticle Views877Altmetric-Citations1360LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The importance of antioxidants which play the role in cellular response against oxidative/nitrosative stress: current state

2015-12-01

Ergül Belge Kurutaş

Remarkable interest has risen in the idea that oxidative/nitrosative stress is mediated in the etiology of numerous human diseases. Oxidative/Nitrosative stress is the result of an disequilibrium in oxidant/antioxidant which … Remarkable interest has risen in the idea that oxidative/nitrosative stress is mediated in the etiology of numerous human diseases. Oxidative/Nitrosative stress is the result of an disequilibrium in oxidant/antioxidant which reveals from continuous increase of Reactive Oxygen and Reactive Nitrogen Species production. The aim of this review is to emphasize with current information the importance of antioxidants which play the role in cellular responce against oxidative/nitrosative stress, which would be helpful in enhancing the knowledge of any biochemist, pathophysiologist, or medical personnel regarding this important issue. Products of lipid peroxidation have commonly been used as biomarkers of oxidative/nitrosative stress damage. Lipid peroxidation generates a variety of relatively stable decomposition end products, mainly α, β-unsaturated reactive aldehydes, such as malondialdehyde, 4-hydroxy-2-nonenal, 2-propenal (acrolein) and isoprostanes, which can be measured in plasma and urine as an indirect index of oxidative/nitrosative stress. Antioxidants are exogenous or endogenous molecules that mitigate any form of oxidative/nitrosative stress or its consequences. They may act from directly scavenging free radicals to increasing antioxidative defences. Antioxidant deficiencies can develop as a result of decreased antioxidant intake, synthesis of endogenous enzymes or increased antioxidant utilization. Antioxidant supplementation has become an increasingly popular practice to maintain optimal body function. However, antoxidants exhibit pro-oxidant activity depending on the specific set of conditions. Of particular importance are their dosage and redox conditions in the cell.

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Antioxidants and antioxidant methods: an updated overview

2020-03-01

İlhami Gülçın

Free radicals in biology and medicine

1985-01-01

Barry Halliwell , John M.C. Gutteridge

Melatonin : a potent, endogenous hydroxyl radical scavenger

1993-01-01

Dx Tan

Evaluating the antioxidant-mediated neuroprotection of hamamelitannin against H₂O₂-induced oxidative damage

2025-06-22

Vishnu Adith Janarthanam , Rupesh Gupta , Alaa S. Alhegaili +2 more | 3 Biotech

Liver Function as a Determinant of Antioxidant Therapeutic Efficacy in Benign Prostatic Hyperplasia: A Systems Biology Perspective

2025-06-21

Bwanbale Geoffrey David | IAA Journal of Applied Sciences

Benign Prostatic Hyperplasia (BPH) is a non-malignant enlargement of the prostate gland predominantly affecting aging males. While oxidative stress (OS) is recognized as a key pathogenic driver in BPH, emerging … Benign Prostatic Hyperplasia (BPH) is a non-malignant enlargement of the prostate gland predominantly affecting aging males. While oxidative stress (OS) is recognized as a key pathogenic driver in BPH, emerging evidence highlights the liver’s critical role in modulating systemic redox homeostasis and influencing antioxidant therapeutic responses. Liver function not only governs the bioavailability, metabolism, and clearance of antioxidant compounds but also contributes to systemic inflammation and metabolic alterations that exacerbate BPH pathophysiology. This review adopts a systems biology approach to explore the complex liver-prostate axis, emphasizing how liver health determines the pharmacokinetics, pharmacodynamics, and therapeutic efficacy of antioxidant interventions in BPH management. We discuss the molecular mechanisms underpinning hepatic regulation of antioxidant bioactivity, the impact of liver dysfunction on BPH progression, and emerging therapeutic strategies aimed at restoring liver-prostate homeostasis. Future research directions advocate for precision antioxidant therapy guided by liver function biomarkers, systems biology modeling, and integrative metabolic profiling. Keywords: Benign Prostatic Hyperplasia; Liver Function; Antioxidant Therapy; Oxidative Stress; Systems Biology

New complex iron with various functionalized 2,2ʹ-bipyridine derivatives in evaluation of total lipophilic and hydrophilic antioxidant capacity by the potentiometry

2025-06-20

E. L. Gerasimova , E. R. Gazizullina , Evgeniya Yanybaeva +6 more | Analytical Sciences

The potentiometric approach for determining the integral antioxidant capacity was developed. The reaction of antioxidants with new complexes of the iron with target functionalized 2,2'-bipyridine derivatives was used as a … The potentiometric approach for determining the integral antioxidant capacity was developed. The reaction of antioxidants with new complexes of the iron with target functionalized 2,2'-bipyridine derivatives was used as a signal-forming reaction. The approach allows the joint determination of hydrophilic and lipophilic antioxidants, which is especially important in the analysis of plant samples with a complex composition. A number of new 2,2'-bipyridine derivatives have been synthesized. It has been shown that the complexing ability, especially with Fe(III), is increased by introducing halogens into the structure of 2,2'-bipyridine. The solubility of the complexes in polar solutions is increased by introducing the triethylene glycol fragment into the 2,2'-bipyridine at the aryl substituent in the C5 position. The electrochemical behavior of the complexes with Fe(II) and Fe(III) was studied. The metal - ligand ratios and stability constants of the complexes were estimated by the voltammetric method (the values of the conditional stability constants ranged from 1∙108 to 5∙1010). Individual antioxidants with different solubilities and cereal extracts, containing antioxidants of different hydrophilicity, were studied by the potentiometric method using promising synthesized complexes. Recovery is about 100%. Relative standard deviation for promising complexes does not exceed 9%. Since the synthesized complexes have a color, they were used in the spectrophotometric method for correlation studies. In addition, the spectrophotometric method using the stable 2,2'-diphenyl-1-picrylhydrazyl radical was chosen as a comparison method. It has been shown that spectrometry using both new complex compounds and the 2,2'-diphenyl-1-picrylhydrazyl radical has limitations in the analysis of colored samples. Since food products are colored, this complicates the analysis by optical methods. Correlations between methods were established in cases of uncolored extracts. Thus, the developed potentiometric approach is not only simple and informative, but can also be used for a wider range of objects.

Improving the Prediction of Antioxidant Activity by Identifying High-Probability Conformations with NMR

2025-06-20

Emily C. Heider , Paula Grace Nickles , Dirk Emde +2 more | Analytical Chemistry

A single-experiment NMR methodology was recently proposed for characterizing chemical structures in solution. This approach employs measured and computed one-bond carbon-carbon J-couplings to establish atomic connectivity, molecular conformation, heteroatom identity, … A single-experiment NMR methodology was recently proposed for characterizing chemical structures in solution. This approach employs measured and computed one-bond carbon-carbon J-couplings to establish atomic connectivity, molecular conformation, heteroatom identity, intramolecular hydrogen bonding, and tautomeric form with high confidence. This methodology also identifies mixtures of conformers and assigns relative amounts. The present study applies this approach to establish conformations in the antioxidants trolox and 3-hydroxythiophene-2-carboxylic acid. The ability to accurately assign conformations in antioxidants is a key step needed before computational mechanistic studies can be successfully performed. In the case of antioxidants, this is especially important because at least four mechanisms of activity are feasible, and an incorrect assignment of conformation can alter mechanistic conclusions. Herein, the NMR methodology is shown to clearly select a single most probable conformation for trolox and two highly probable conformations of 3-hydroxythiophene-2-carboxylic acid. The NMR analysis also identified a possible conformational error in prior computational studies involving trolox.

Prooxidative properties of aldehydes in oil-in-water emulsion on the aspects of physicochemical properties

2025-06-19

KeunCheol Yoo , ChanHyung Kim , Won Young Oh +1 more | Food Science and Biotechnology

Design, Synthesis, Theoretical Study, and Antioxidant Activity of Aromaticity-Extended Resveratrol Derivatives Incorporating Chalcogen

2025-06-19

Sangwon Ko , Hyun Min Lim , Yeonho Song +2 more | International Journal of Molecular Sciences

Naturally occurring antioxidants have attracted significant research interest, owing to their radical scavenging ability that can be improved via structural modifications. In this study, aromaticity-extended resveratrol analogues (3-5) containing chalcogens … Naturally occurring antioxidants have attracted significant research interest, owing to their radical scavenging ability that can be improved via structural modifications. In this study, aromaticity-extended resveratrol analogues (3-5) containing chalcogens were designed and synthesized using ring closure and Horner-Wadsworth-Emmons reactions. The antioxidant activities of the derivatives were evaluated using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABST) assay. All resveratrol derivatives (3-5) exhibited higher radical scavenging activities than resveratrol 1 and analogue 2, with benzoselenophene-conjugated derivative 5 demonstrating the highest activity. The improved antioxidant performance of the resveratrol derivatives was attributed to the extended π conjugation resulting from the incorporation of fused rings, benzoheteroles. Additionally, the integration of benzoheteroles into resveratrol contributed to an efficient reduction in HOMO-LUMO gaps. This study demonstrates that aromaticity extension by introducing benzofuran, benzothiophene, and benzoselenophene is a feasible strategy for improving the antioxidant activity of naturally occurring oxidants.

Nature-Inspired Redox Active Organic Molecules: Design, Synthesis, and Characterization of Pyridine Derivatives

2025-06-18

Gloria Acosta , Martha M. Flores‐Leonar , Jazmín García-Ramírez +2 more | Chemistry

In this article, we present experimental and theoretical studies of pyridine derivatives (pyDs) inspired by natural systems to investigate the electron transfer processes occurring in aqueous media and elaborate a … In this article, we present experimental and theoretical studies of pyridine derivatives (pyDs) inspired by natural systems to investigate the electron transfer processes occurring in aqueous media and elaborate a theoretical model that adequately predicts the behavior of new derivatives. Our results might be relevant to scientific and technological applications, including energy storage, redox-active scaffolds for organic synthesis, photoredox catalysis, and new materials. The synthesis of eight pyDs is reported. To improve water solubility, six new compounds are hexafluorophosphate alkylammonium salts. The pyDs exhibit irreversible redox processes, with electron-donating substituents decreasing the cathodic peak potential while electron-withdrawing groups increase it; when both substituents are present, the latter effect prevails. A computational study was performed to investigate the electrochemical behavior of the synthesized compounds and design new electroactive pyDs. DFT calculations provided the predominant species’ redox potentials and acidity constants to elaborate Pourbaix diagrams for each compound. The synthesized molecules exhibit a two-electron-one-proton dismutation process in the water pH window. Beyond this range, stabilized radical species undergo one-electron exchange processes. We correlated experimental and calculated parameters, screening 22 additional derivatives to evaluate their electrochemical behavior, identifying potential candidates capable of performing a one-electron transfer process in the pH window of water, revealing new applications for pyDs.

ORGANOMETALLIC COMPOUND’S PHOTOTOXICITY AGAINST CANCER CELLS

2025-06-17

C. Hazarathaiah Yadav , Narendra Revanuri , Abdul Razak Mohamed Sikkander | Biomedical Engineering Applications Basis and Communications

Organometallic compounds have recently emerged as a hot topic in the field of cancer research owing to their unorthodox and promising therapeutic potential. One attractive development project is their phototoxicity … Organometallic compounds have recently emerged as a hot topic in the field of cancer research owing to their unorthodox and promising therapeutic potential. One attractive development project is their phototoxicity for targeted cancer therapy. In general, these materials consist of metal-to-ligand charge transfer sensitizers and hence display very different photochemical properties than ordinary organic molecules. Objectives: In the current study, we evaluated whether organometallic compounds are appropriate to become novel photodynamic agents for photocytotoxic activity. Methods: A variety of organometallic compounds were synthesized and characterized. In vitro phototoxicity of these compounds was evaluated on various cancer cell lines. This includes measuring cell viability, apoptosis, and reactive oxygen species (ROS) generation after exposure to compounds in the presence of light at specific wavelengths. Conclusion: Many of the organometallic compounds examined were quite phototoxic when activated with light. The toxicity changed depending on the metal center and the nature of ligands (organic). These compounds increased ROS production and tumor cell apoptosis. Comparative studies demonstrated that certain organometallic compounds exhibited higher activity against cancer cells than the currently used photodynamic therapy (PDT) agents. Organometallic compounds can be considered strong phototoxic agents for more evolved PDT. When exposed to light, these chemicals selectively injure cancer cells and thus may provide more effective therapeutic options with fewer side effects than existing treatments. Nevertheless, more complete research is required to fine-tune such compounds and elucidate the precise mechanisms of action. The hallmarks of photodynamic anticancer effects triggered by organometallic compounds and various forms in which they gain access to the target cells are presented here.

Food Grade Synthesis of Hetero-Coupled Biflavones and 3D-Quantitative Structure–Activity Relationship (QSAR) Modeling of Antioxidant Activity

2025-06-16

Hongling Zheng , Xin Yang , Qiuyu Zhang +2 more | Antioxidants

Biflavonoids are a unique subclass of dietary polyphenolic compounds known for their diverse bioactivities. Despite these benefits, these biflavonoids remain largely underexplored due to their limited natural availability and harsh … Biflavonoids are a unique subclass of dietary polyphenolic compounds known for their diverse bioactivities. Despite these benefits, these biflavonoids remain largely underexplored due to their limited natural availability and harsh conditions required for their synthesis, which restricts broader research and application in functional foods and nutraceuticals. To address this gap, we synthesized a library of rare biflavonoids using a radical-nucleophile coupling reaction previously reported by our group. The food grade coupling reaction under weakly alkaline water at room temperature led to isolation of 28 heterocoupled biflavones from 11 monomers, namely 3',4'-dihydroxyflavone, 5,3',4'-trihydroxyflavone, 6,3',4'-trihydroxyflavone, 7,3',4'-trihydroxyflavone, diosmetin, chrysin, acacetin, genistein, biochanin A, and wogonin. The structures of the dimers are characterized by nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectroscopy (HRMS). In addition, we evaluated the antioxidant potential of these biflavones using a DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay and the DPPH value ranges between 0.75 to 1.82 mM of Trolox/mM of sample across the 28 synthesized dimers. Additionally, a three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis was conducted to identify structural features associated with enhanced antioxidant activity. The partial least squares (PLS) regression QSAR model showed acceptable r2 = 0.936 and q2 = 0.869. Additionally, the average local ionization energy (ALIE), electrostatic potential (ESP), Fukui index (F-), and electron density (ED) were determined to identify the key structural moiety that was capable of donating electrons to neutralize reactive oxygen species.

Application of Hansen Solubility Parameters in the Aqueous-Ethanol Extraction of Genistein-7-O-[α-rhamnopyranosyl-(1→6)]-β-glucopyranoside from Derris scandens and Its Molecular Orbital Study on Antioxidant Activity

2025-06-15

Thitiporn Tantinithiphong , Wanna Eiamart , Sarin Tadtong +2 more | International Journal of Molecular Sciences

This study explored the extraction of genistein-7-O-[α-rhamnopyranosyl-(1→6)]-β-glucopyranoside (GTG) from Derris scandens using an aqueous-ethanol solvent system, aiming to optimize yield and antioxidant activity. Hansen solubility parameters (HSP) were employed to … This study explored the extraction of genistein-7-O-[α-rhamnopyranosyl-(1→6)]-β-glucopyranoside (GTG) from Derris scandens using an aqueous-ethanol solvent system, aiming to optimize yield and antioxidant activity. Hansen solubility parameters (HSP) were employed to determine the optimal solvent composition, with the highest GTG yield (6.83 ± 0.06 mg/g dried weight) obtained from 50% ethanol-correlating well with HSP predictions. Ultrasonic extraction was most effective with solvents having a dielectric constant between 50 and 60. The antioxidant potential of isolated GTG was evaluated using the DPPH assay, which yielded an IC50 of 87.86 ± 1.85 μM, and the FRAP assay, with a value of 34.23 ± 2.75 mg FeSO4 equivalents. Molecular orbital analysis revealed HOMO and LUMO energy gaps (ΔE = 10.6715 eV) similar to known antioxidants such as gallic acid, ascorbic acid, Trolox, and quercetin. These findings demonstrate that HSP effectively guided solvent selection for ultrasound-assisted extraction of GTG. The antioxidant activity is attributed to GTG's capacity to donate electrons and stabilize radicals via extended charge delocalization within the aglycone structure, confirming its potential as a natural antioxidant agent.

Structural and biological properties of isoproterenol, comparison with epinephrine and norepinephrine

2025-06-13

Marija Milosavljević , Đura Nakarada , Marta Gostiljac +4 more | Journal of Chemical Sciences

Dihydroquercetin and Related Flavonoids in Antioxidant Formulations with α-Tocopherol

2025-06-13

Vera V. Olicheva , V. L. Beloborodov , Seyed Davood Sharifi +4 more | International Journal of Molecular Sciences

The concomitant utilization of flavonoids and α-tocopherol has the potential to establish a comprehensive antioxidant system that operates in both hydrophilic and lipophilic environments. The objective of this study was … The concomitant utilization of flavonoids and α-tocopherol has the potential to establish a comprehensive antioxidant system that operates in both hydrophilic and lipophilic environments. The objective of this study was to examine the antioxidant interactions between dihydroquercetin, a flavonoid that has shown promise in various studies, as well as structurally related flavonoids, and α-tocopherol in various ratios. The antioxidant capacity was assessed using two ABTS•+ radical-cation inhibition assays: a decolorization assay and a lag-time assay. The results of this study indicated that formulations of dihydroquercetin, quercetin, rutin, or morin with α-tocopherol exhibited additive or mildly subadditive interactions, independent of their ratios. A two-phase pattern was exhibited by the lag-time data, which, in comparison with individual components, allowed us to suggest that α-tocopherol appeared to dominate the initial phase of radical scavenging, while flavonoids became active in the later phase. This finding indicates that α-tocopherol may play a role in protecting flavonoids from premature oxidation in alcoholic media. The findings could prove valuable for the rational design of antioxidant formulations in the nutraceutical, cosmeceutical, and pharmaceutical industries. Additionally, the two-stage antioxidant behavior offers prospects for the formulation of straightforward, cost-effective analytical approaches to measure components in binary antioxidant formulations.

Anti‐Inflammatory Activity of Sarcoaldosterol A Isolated From Heteroxenia fuscescens: Insights From In Vitro, In Silico, and Spectroscopic Studies

2025-06-13

Rwaida A. Al Haidari , Fahd M. Abdelkarem , Bandar D. Alrehaili +4 more | Chemistry & Biodiversity

ABSTRACT Chronic inflammation is a key factor in the progression of many diseases, driving ongoing efforts to identify new and effective anti‐inflammatory agents. Sarcoaldosterol A, a polyhydroxylated gorgostane steroid isolated … ABSTRACT Chronic inflammation is a key factor in the progression of many diseases, driving ongoing efforts to identify new and effective anti‐inflammatory agents. Sarcoaldosterol A, a polyhydroxylated gorgostane steroid isolated from Heteroxenia fuscescens , was evaluated for its anti‐inflammatory activity using in vitro studies, molecular docking, and quantum chemical calculations. Its structure was elucidated on the basis of 1D NMR, HR‐ESI‐MS, and comparison with literature. Sarcoaldosterol A significantly inhibited pro‐inflammatory mediators nuclear factor‐kappa B ( NF‐κB ), tumor necrosis factor ( TNF‐α ), interleukin‐1 beta ( IL‐1β ), and Toll‐like receptor 4 ( TLR‐4 ), while upregulating the anti‐inflammatory cytokine interleukin‐10 (IL‐10). It also showed moderate inhibition of cyclooxygenase‐2 (COX‐2) (IC 50 = 18.57 ± 0.61 µg/mL). Molecular docking confirmed COX‐2 binding affinity, and quantum calculations elucidated its chemical stability and reactivity. As the first reported polyhydroxylated gorgostane steroid with such activity, Sarcoaldosterol A holds promising candidate for future exploration as a molecular scaffold in inflammation‐related drug discovery.

Computational-Chemistry-Based Prediction of Near-Infrared Rhodamine Fluorescence Peaks with Sub-12 nm Accuracy

2025-06-12

Qiupeng Yuan , Hanwei Wang , Pingping Sun +2 more | Photochem

Near-infrared (NIR) rhodamine dyes are pivotal for bioimaging due to the minimal tissue interference. Yet, their rational design is hindered by unreliable computational methods for excited-state property prediction. We benchmarked … Near-infrared (NIR) rhodamine dyes are pivotal for bioimaging due to the minimal tissue interference. Yet, their rational design is hindered by unreliable computational methods for excited-state property prediction. We benchmarked the time-dependent density functional theory (TDDFT) with the linear-response (LR) and state-specific (SS) solvation models across five functionals (CAM-B3LYP, M06-2X, ωB97X-D, B3LYP, MN15) and optimized the ground/excited states for 42 rhodamine derivatives. A robust linear calibration framework was established by connecting the computed and experimental wavelengths, which was rigorously validated through six-fold cross-validation. The key metrics included the mean absolute error (MAE) and R2 to assess the prediction robustness. CAM-B3LYP combined with LR solvation achieved the highest accuracy (absorption: MAE = 6 nm, R2 = 0.94; emission: MAE = 12 nm, R2 = 0.72). By integrating the TDDFT with a calibrated linear-response solvation model, we achieved sub-12 nm accuracy in predicting the NIR fluorescence peaks. This framework enabled the rational design of nine novel rhodamine derivatives with emissions beyond 700 nm, offering a paradigm shift in bioimaging probe development.

Radical Scavenging Activity: DFT and Multilinear Regression Studies of Benzofuran-1,3-thiazolidin-4-one Derivatives

2025-06-11

Fella Ati , Soraya Abtouche , Boubekeur Maouche +1 more | Acta chimica slovenica

The free radical scavenging activity of benzofuran Schiff base and thiazolidinone derivatives has been investigated using the density functional theory (DFT) calculations. Three primary mechanisms were developed: sequential proton loss … The free radical scavenging activity of benzofuran Schiff base and thiazolidinone derivatives has been investigated using the density functional theory (DFT) calculations. Three primary mechanisms were developed: sequential proton loss electron transfer (SPLET), single electron transfer followed by proton transfer (SET-PT), and hydrogen atom transfer (HAT). Several thermodynamic descriptors were computed in both gas and solvent phases at the B3LYP/6-311G and 6-311G (d, p) level of theory. Our findings suggest that compounds 3a, 3c, 3f, 4d, and 4e may scavenge free radicals through one of these three pathways. The results indicate that SPLET is favored in polar environments, while HAT is the thermodynamically preferred mechanism in the gas phase and non-polar solutions. Electron-withdrawing groups (EWG) attached to the π conjugated system at the N position of the benzofuran derivatives decrease bond dissociation enthalpies (BDE), while electron-donating groups (EDGs) are helpful to decrease the ionization potentials (IPs). The results of the multilinear regression statistical analyses indicate a good correlation between the IC50 and ionization potential, in addition to the proton dissociation enthalpy, proton affinity, and the electron transfer enthalpy descriptors.

Quantum chemical insights into the antioxidant mechanisms of luteolin and isorhamnetin: Elucidating structure-reactivity relationships, pharmacokinetics, and toxicity for therapeutic potential

2025-06-09

Babatunde Temitope Ogunyemi | Communication in Physical Sciences

This study presents a comprehensive computational evaluation of the antioxidant properties, physicochemical characteristics, pharmacokinetics, and toxicity profiles of two naturally occurring flavonoids—luteolin and isorhamnetin. Using quantum chemical descriptors and density … This study presents a comprehensive computational evaluation of the antioxidant properties, physicochemical characteristics, pharmacokinetics, and toxicity profiles of two naturally occurring flavonoids—luteolin and isorhamnetin. Using quantum chemical descriptors and density functional theory (DFT) at the B3LYP/6-31G(d,p) level, we assessed the bond dissociation enthalpy (BDE), adiabatic ionization potential (AIP), proton dissociation enthalpy (PDE), proton affinity (PA), and electron transfer enthalpy (ETE) of both compounds. Isorhamnetin demonstrated superior antioxidant potential, with lower BDE values (79 kcal/mol in vacuum and 71 kcal/mol in water) compared to luteolin (84 and 82 kcal/mol, respectively), suggesting enhanced hydrogen atom donation capacity via the HAT mechanism. Bond order analysis showed higher stability in O3–H1 and O6–H8 bonds (up to 0.773), indicating site-specific reactivity. Pharmacokinetic simulations predicted high gastrointestinal absorption and blood-brain barrier permeability for both compounds, with zero violations of Lipinski, Veber, and Muegge rules. However, toxicity assessments flagged both molecules as mutagenic with medium hERG-related cardiotoxic risk. Notably, isorhamnetin exhibited better aqueous solubility (ESOL class: soluble) than luteolin (moderately soluble), further supporting its potential bioavailability. Overall, isorhamnetin appears to be a more favorable candidate for therapeutic applications, although both require further experimental validation for safety and efficacy.

Comprehensive Oxidation Mechanism of n-Butylamine and 2-Butylamine by H and OH Radicals: Insights into Reactivity

2025-06-02

Joel Leitão Nascimento , Tiago Vinicius Alves , Yanlei Shang | The Journal of Physical Chemistry A

This study presents the accurate thermal rate constants for a series of hydrogen abstraction reactions involving 1- and 2-butylamine and key radicals H and OH. The potential energy surface resulting … This study presents the accurate thermal rate constants for a series of hydrogen abstraction reactions involving 1- and 2-butylamine and key radicals H and OH. The potential energy surface resulting from these reactions was examined by using the M08-HX/ma-TZVP level of theory. The rate coefficients were calculated within the multistructural canonical variational theory with small-curvature tunneling correction (MS-CVT/SCT). Multistructural effects and the torsional anharmonicity corrections were evaluated through the rovibrational partition function calculated with the multistructural method based on a coupled torsional potential (MS-T). Our results demonstrated an influence of the position of the amino functional group on the kinetics. The gradual decrease in barrier heights was observed with increasing distance between the amino functional group and the reaction site. The calculated branching ratios demonstrated that the H-abstraction by the H radicals at the α-site is favored. In reactions involving OH radicals, the channel at the N-site shows a greater proportion due to its increased multistructural torsional anharmonicity and a reduced variational effect of other sites.

Antimicrobial Evaluation and Photophysical Properties of Zinc(II) and Cadmium(II) Complexes Based on Pyrazolyl and Pivalate Ligands

2025-06-01

Lakshmi Krishnaa Suresh , M. Simi , Punit Prakash +3 more | Journal of Physics Conference Series

Abstract This study focuses on the synthesis, characterization, and evaluation of the antimicrobial and photophysical properties of Zn(II) and Cd(II) complexes utilizing 3,5-dimethyl pyrazolate (DMPz − ) and pivalate (Piv) … Abstract This study focuses on the synthesis, characterization, and evaluation of the antimicrobial and photophysical properties of Zn(II) and Cd(II) complexes utilizing 3,5-dimethyl pyrazolate (DMPz − ) and pivalate (Piv) ligands. The complexes were synthesized through a straightforward coordination reaction by a one-pot mixing of metal salt and ligands at room temperature. Their structural integrity was confirmed using spectroscopic techniques, including, IR, UV-Visible, and NMR spectroscopy as well as single-crystal X-ray diffraction analysis. The antimicrobial activity of the synthesized complexes was evaluated against a range of bacterial and fungal strains using standard antimicrobial assays. The results revealed significant antimicrobial efficacy for both Zn and Cd complexes, with variations in effectiveness depending on the metal center and the coordination behaviour of the ligands in the solution. In addition to their biological activity, the fluorescence properties of the complexes were explored, revealing distinct emission spectra. These photophysical characteristics highlight the potential of the synthesized Zn and Cd complexes for applications in bioimaging and sensing technologies. This study establishes a clear correlation between the chemical structure, antimicrobial performance, and fluorescence behaviour of these complexes. The findings provide valuable insights for the development of novel antimicrobial agents and luminescent materials, offering promising advancements in the fields of medicinal chemistry and photophysical materials.

Computational exploration of a chlorinated tetrahydroisoquinoline: Geometry, reactivity, noncovalent interactions, and molecular docking evaluation

2025-06-01

Mouslim Messali , Gaurav Jhaa , Awad A. Alrashdi +5 more | Results in Physics

STRUCTURAL PROPERTIES, MOLECULAR MODELING STUDIES AND ANTIOXIDANT ACTIVITIES OF NOVEL BENZOIC ACID-BASED AZO MOLECULES: A COMBINED IN VITRO AND IN SILICO STUDY

2025-06-01

Mehmet Ulutürk , Çiğdem Karabacak Atay , Tahir Tilki +1 more | Journal of Molecular Structure

Investigation of free radical scavenging activities of some Isatin Schiff bases (O-H versus N-H). A DFT Study

2025-06-01

Habiba Boudiaf , Nadjia Latelli , Roumaissa Khelifi +4 more | Chemical Physics Impact

Thiosemicarbazide Derivative of Captopril (8) imposes Cellular-Dependent Death Modalities on Breast Cancer Cell Lines

2025-06-01

Baan Majid Aljasani , Hayder B. Sahib , Hiba Najeh Al-Saad | Asian Pacific Journal of Cancer Prevention

Breast cancer prevalence is continuing to rise worldwide. Despite the diversity of the current approaches and protocols to treat this heterogeneous disease, most of these face the challenges of side … Breast cancer prevalence is continuing to rise worldwide. Despite the diversity of the current approaches and protocols to treat this heterogeneous disease, most of these face the challenges of side effects and resistance. Hence, novel and innovative approaches to the treatment of breast cancer are almost constantly needed. This study aimed to investigate the antiproliferative and death modalities induced by three thiosemicarbazide derivatives of captopril in two subtypes of breast cancer cell lines, the Estrogen- receptor positive MCF-7, and the Estrogen/progesterone- receptor-negative AMJ13. MTT assay was used to determine the cytotoxicity of the derivatives and their parent compound Captopril, Hematoxylin and Eosin (H&E) staining, Acridine Orange/ Ethidium Bromide (AO/EtBr) staining, Caspase immunocytochemistry analysis and ROS generation by Human ROMO1 ELISA assays were conducted to explore the type of cellular death induced by these derivatives. One of the derivatives denoted as (8) demonstrated the best antiproliferative profile recording the highest cytotoxic effect with IC50 of (88.06 µM) and (66.82 µM) compared to that of captopril (849.8 µM),(1075µM) in MCF-7 and AMJ13 breast cancer cells respectively. In MCF-7 cells, derivative (8) imposed an apoptotic cellular death with the involvement of caspase-3, and caspase-9 and displayed a time-dependent ROS generation. In AMJ13 breast cancer cells, results revealed an extensive vacuole forming, non-apoptotic cellular death, without ROS generation, but with a significant implication of caspase-9. Conclusion: This study demonstrated the thiosemicarbazide derivative of captopril (8) as a promising antiproliferative agent against breast cancer cells displaying different cellular death modalities, signifying the versatility of the derivative and suggesting multitarget pathways. This study strongly recommends derivative (8) as a future leading molecule.

Zn(II), Cu(II), and Fe(III) complexes of 2-(((4-(Methylselanyl)phenyl)imino)methyl)phenol: Synthesis, characterization, and multidisciplinary investigations

2025-06-01

Saad Shaaban , Tarek A. Yousef , Ahmed S. Al‐Janabi +7 more | Polyhedron

Multifaceted Analysis of a p-Coumaric Acid-Tryptamine Organic Salt: Structure, Spectra, Computational Modelling, and Biological Potential

2025-06-01

A. Agalya , S. Muthu , Nandhini Chakkarapani +4 more | Journal of Molecular Structure

[Determination of 22 organic ultraviolet absorbers in human serum by ultra performance liquid chromatography- tandem mass spectrometry].

2025-06-01

Dejun Bao , Zhongke Feng , Xu Zhang +5 more

In this study， a method for the simultaneous determination of 22 organic ultraviolet absorbers （OUVs） in human serum was established by combining protein precipitation technology （PPT）， efficiency lipid removal technology … In this study， a method for the simultaneous determination of 22 organic ultraviolet absorbers （OUVs） in human serum was established by combining protein precipitation technology （PPT）， efficiency lipid removal technology （ELR） and ultra performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）. The OUVs include five benzophenone compounds， five benzotriazole compounds， two cinnamate ester compounds and their three metabolites， two salicylate compounds， two camphor derivative compounds， one triazine compound， one dibenzoylmethane compound and one amino aminobenzoic acid derivative compound. Chromatography was performed using an Acquity BEH C18 column （100 mm×2.1 mm， 1.7 μm）， gradient elution was carried out using methanol-water and methanol-0.1% ammonia water as the mobile phases. Compounds were detected in both positive and negative electrospray ionization （ESI+/ESI‒） modes using multiple reaction monitoring （MRM）， and quantified using stable-isotope internal standards. The experimental results showed that the 22 target compounds exhibited good linear relationships within their respective linear ranges， with the correlation coefficients （r）≥0.999 3. The method detection limits （MDLs） ranged from 0.02 to 0.48 ng/mL， and the method quantification limits （MQLs） ranged from 0.02 to 1.60 ng/mL. At the three spiked levels of low， medium and high， the spiked recoveries of the 22 target analytes ranged from 79.9% to 136.1%， the intra-day precisions were from 1.5% to 25.4%， and the inter-day precisions were from 0.6% to 23.5%. After correction by the stable-isotope internal standard method， the matrix effects of the 22 target analytes in fetal bovine serum were 83.0%‒119.9%. The developed method was successfully used to detect 22 OUVs in 110 human serum samples. With the exception of 3-benzylidene camphor （3-BC）， 2-（2H-benzotriazol-2-yl）-4-methyl-6-（2-propenyl）phenol （UV-9）， 4-methylbenzylidene camphor （4-MBC）， 2，2'-dihydroxy-4-methoxybenzophenone （BP-8）， and 2，4-dihydroxybenzophenone （BP-1）， which were not detected， the remaining 17 substances were detected with overall detection rates of 0.9%-65.5% and the detection levels were <MQL‒11.7 ng/mL. The developed analytical method is simple， convenient， highly sensitive， and is expected to become an effective tool for quantifying 22 OUVs in human serum.