Antiradical and antioxidant activities of new bio-antioxidants (original) (raw)
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Phenolic antioxidants â radical-scavenging and chain-breaking activity: A comparative study
European Journal of Lipid Science and Technology, 2009
Fifty phenolic antioxidants (AH) (42 individual compounds and 8 binary mixtures of two antioxidants) were chosen for a comparative analysis of their radical-scavenging (H-donating) and chain-breaking (antioxidant) activity. Correlations between experimental (antiradical and antioxidant) and predictable (theoretical) activities of 15 flavonoids, 15 hydroxy cinnamic acid derivatives, 5 hydroxy chalcones, 4 dihydroxy coumarins and 3 standard antioxidants (butylated hydroxytoluene, hydroquinone, DL-atocopherol) were summarized and discussed. The following models were applied to explain the structureactivity relationships of phenolic antioxidants of natural origin: (a) model 1, a DPPH assay used for the determination of the radical-scavenging capacity (AH 1 DPPH . ? A . 1 DPPH-H); (b) model 2, chemiluminescence of a model substrate RH (cumene or diphenylmethane) used for the determination of the rate constant of a reaction with model peroxyl radicals (AH 1 RO 2 . ? ROOH 1 A . ); (c) model 3, lipid autoxidation used for the determination of the chain-breaking antioxidant efficiency and reactivity (AH 1 LO 2 . ? LOOH 1 A . ; A . 1 LH (1O 2 ) ? AH 1 LO 2 . ); and (d) model 4, theoretical methods used for predicting the activity (predictable activity). The highest lipid oxidation stability was found for antioxidants with a catecholic structure and for their binary mixtures with DL-a-tocopherol, as a result of synergism between them.
Free Radicals and Antioxidants, 2014
Introduction: The antioxidant and radical scavenging properties of some of the hydroxy phenyl derivatives such as 4-Hydroxybenzoic acid (1), 3-Hydroxy-4-methoxycinnamic acid (2), 3-(4-Hydroxy-3,5-dimethoxyphenyl)prop-2enoic acid (Sinapic acid) (3), 4-Hydroxy-3,5-dimethoxybenzoic acid (4), 3,4-Dihydroxycinnamic acid (Caffeic acid) (5) and 5-Isopropyl-2-methylphenol (6), which are naturally present in fruits and vegetables, were investigated. Methods: The following analysis were conducted: The total antioxidant activity via the ferric thiocyanate method; 2,2'-azinobis-(3-ethylbenzothiazole-6-sulphonate) (ABTS) radical scavenging activity; superoxide anion radical (O 2 •-) scavenging activity; the total reduction power through potassium ferricyanide reduction method; Cupric ions (Cu 2+) reduction capacity through Cuprac method; hydrogen peroxide scavenging activity and chelating activity of ferrous ions (Fe 2+). Furthermore, α-tocopherol, butylatedhydroxyanisole (BHA) and quercetin were used as the reference antioxidant compounds. Results: In the comparison of initial states and the products, it's observed that at the 50th hour the linoleic acid emulsion at 30 μg/mL concentration inhibited the lipid peroxidation by 85%, 60.7%, 69%, 45.4%, 80.4% and 31%, respectively. On the other hand, it's observed that the linoleic acid emulsion of α-tocopherol, (BHA) and quercetin inhibited the lipid peroxidation by 62.65%, 35.84% and 34.82% respectively, at the same concentration. Conclusions: It's found as a result of our studies that some of the phenolic compounds such as 4-Hydroxybenzoic acid (1), 3-Hydroxy-4-methoxycinnamic acid (2), 3-(4-Hydroxy-3,5-dimethoxyphenyl)prop-2-enoic acid (3), 4-Hydroxy-3,5dimethoxybenzoic acid (4), 3,4-Dihydroxycinnamic acid (5) and 5-Isopropyl-2-methylphenol (6) which are naturally present in foods. They have higher total antioxidant activity, radical scavenging and metal chelating activities than the widely used powerful antioxidant compounds such as BHA, Quercetin and α-tocopherol.
Recent Developments in Effective Antioxidants: The Structure and Antioxidant Properties
Materials, 2021
Since the last few years, the growing interest in the use of natural and synthetic antioxidants as functional food ingredients and dietary supplements, is observed. The imbalance between the number of antioxidants and free radicals is the cause of oxidative damages of proteins, lipids, and DNA. The aim of the study was the review of recent developments in antioxidants. One of the crucial issues in food technology, medicine, and biotechnology is the excess free radicals reduction to obtain healthy food. The major problem is receiving more effective antioxidants. The study aimed to analyze the properties of efficient antioxidants and a better understanding of the molecular mechanism of antioxidant processes. Our researches and sparing literature data prove that the ligand antioxidant properties complexed by selected metals may significantly affect the free radical neutralization. According to our preliminary observation, this efficiency is improved mainly by the metals of high ion pot...
Chemistry Central Journal, 2013
Background: Phenolic compounds are widely distributed in plant kingdom and constitute one of the most important classes of natural and synthetic antioxidants. In the present study fifty one natural and synthetic structurally variant phenolic, enolic and anilinic compounds were examined as antioxidants and radical scavengers against DPPH, hydroxyl and peroxyl radicals. The structural diversity of the used phenolic compounds includes monophenols with substituents frequently present in natural phenols e.g. alkyl, alkoxy, ester and carboxyl groups, besides many other electron donating and withdrawing groups, in addition to polyphenols with 1-3 hydroxyl groups and aminophenols. Some common groups e.g. alkyl, carboxyl, amino and second OH groups were incorporated in ortho, meta and para positions. Results: SAR study indicates that the most important structural feature of phenolic compounds required to possess good antiradical and antioxidant activities is the presence of a second hydroxyl or an amino group in o-or p-position because of their strong electron donating effect in these positions and the formation of a stable quinone-like products upon two hydrogen-atom transfer process; otherwise, the presence of a number of alkoxy (in o or p-position) and /or alkyl groups (in o, m or p-position) should be present to stabilize the resulted phenoxyl radical and reach good activity. Anilines showed also similar structural feature requirements as phenols to achieve good activities, except o-diamines which gave low activity because of the high energy of the resulted 1,2-dimine product upon the 2H-transfer process. Enols with ene-1,2-diol structure undergo the same process and give good activity. Good correlations were obtained between DPPH inhibition and inhibition of both OH and peroxyl radicals. In addition, good correlations were obtained between DPPH inhibition and antioxidant activities in sunflower oil and liver homogenate systems.
The novel antioxidant activity method for phenolic compounds
2013
A simple sensitive spectrophotometric method was developed using Phenolic compounds. The method is based on the reaction of the secondary amine as n-electron donor with the π-acceptor 2,3,5,6-tetra chloro 1,4-benzo quinone. The coloured charge-transfer complex was measured at 412nm. The Free radical generation was confirmed with the polymerization of acrylonitrile with charge transfer complex as initiator. The procedure was applied successfully to the determination of the Free radical Scavenging activity of the title compounds. Among the Sixteen analogs, V 16 exhibited highest antioxidant activity and very low IC 50 value, V 6 exhibited least antioxidant activity with highest IC 50 value. In the present study, Quantitative Structure-activity relationship modeling was performed on a series of Phenolic derivatives. IP, EN, Soft and EI are found to be the explainable variables for the semi empirical methods. The statistical parameters from the models indicate that the data well fitted ...
2023
Antioxidants are vital bioactive components that garnered the attention of various researchers in the area of pharmacy, medicine, and food engineering. Here we have endeavored our effort to highlight the significance of antioxidants and critical assay methods to analyze the inhibitory activity of the antioxidants. Various in vitro and in vivo assay methods are available to estimate the inhibitory activity of which, the hydroxyl radical antioxidant capacity (HORAC) test, the oxygen radical absorption capacity (ORAC) test, the total oxyradical scavenging capacity (TOSC) test, and the total peroxyl radical trapping antioxidant parameter (TRAP) test are based on the transfer of hydrogen atom. The ferric reducing antioxidant power (FRAP) test, cupric reducing antioxidant power (CUPRAC) test, and the folin-ciocalteu test is based on a transfer of an electron. Whereas, the [2,2-di(4tert-octylphenyl)-1-picrylhydrazyl] (DPPH) test and, 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) tests are based on transfer of both hydrogen and electron. All these assays preliminarily assess the chemical kinetics to reach the chemical equilibrium state and develop chromogenic color or discoloration or develop fluorescence or quenches the fluorescence which can be analyzed in colorimeter or spectrophotometer respectively. In the present review, we have summarized the synthesis of antioxidant materials and their significance and the assay methods which were employed to estimate the inhibitory activity of the antioxidants.
2011
The purpose of this study is to evaluate and compare the free radical scavenging activity and protective properties of the natural product SQGD-IBG-21 isolated from a radioresistant bacterium Bacillus sp. INM-1 and synthetic nitroxyl free radical containing antioxidant 1-ethyl-1-nitroso-3-[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)]-urea (SLENU). It was found a higher reducing power potential for SQGD (1.336±0.03357 U abs) comparing to that of SLENU (0.196±0.002273U abs); a higher nitric oxide radical scavenging activity 35.645 ±1,122% for SQGD in comparison with SLENU (19.964±2.233%). Total antioxidant capacity of SQGD was found to be 75±0.06%, while for SLENU it was only 22±0.03%. Maximum protection to the liposomes calculated in % inhibitory activity of two agents was found to be 50.04±0.037% for the natural agent and 27.54±0.33% for nitroxyl-labeled agent. By direct EPR spectroscopy stable radical structures were recorded in the solutions of both studied antioxidants: an o-semiquinone radical structure was recorded in aqueous solution of SQGD and nitroxyl free radical struture in the ethanol solution of SLENU, respectively. It should be mentioned that the natural antioxidant possesses higher protective properties in comparison with the synthetic antioxidant. In conclusion, because of well expressed free radical scavenging and antioxidant activities of both studied agents they might be used in the combination anticancer chemotherapy for reduction the toxicity caused by anticancer drugs and/or radiation therapy.
Density functional theory studies of the antioxidants-a review
journal of molecular modeling, 2021
The following review article attempts to compare the antioxidant activity of the compounds. For this purpose, density functional theory/Becke three-parameter Lee-Yang-Parr (DFT/B3LYP) methodology was carried out instead of using pharmacological methodologies because of economic benefits and high accuracy. This methodology filtrates the compounds with the lowest antioxidant activity. At first, the Koopmans' theorem was carried out to calculate some descriptors to compare antioxidants. The energy of the highest occupied molecular orbitals (HOMO) was accepted as the best indicator, and then some studies confirmed that the highest occupied molecular orbital/lowest unoccupied molecular orbital (HOMO-LUMO) energy gap is the more precise descriptor. Although it would be better to compare spin density distribution (SDD) on the oxygen of the corresponding radical in the polarizable continuum model (PCM) to evaluate their capability to chain reaction inhibition. Next, it was mentioned that in the multi-target directed ligands (MTDLs), the antioxidant is connected to other moieties in para positions to create better antioxidants or novel hybrid compounds. Indeed, SDD was introduced as a descriptor for MTDL antioxidant effectiveness. Then, the relation between antioxidants and aromaticity was investigated. The more the aromaticity of an antioxidant, the more stable the corresponding radical is. Subsequently, in preferred antioxidant activity, it was defined that the hydrogen atom transfer (HAT) mechanism is more favored in metabolism phase I. It has been seen that the solvent model can change the antioxidant mechanism. Therefore, the solvent model is more important than the chemical structure of antioxidants, and an ideal antioxidant should be evaluated in PCM for pharmacological evaluations.
A Theoretical Study on the Structure-Radical Scavenging Activity of Some Hydroxyphenols
Physical Chemistry Research, 2016
Antioxidants are made for the struggle and reconstruction of the damaged cells, because of their ability in destroying the free radicals. On account of their importance, a theoretical procedure was applied for the study of the molecular structure and radical scavenging activity of six hydroxyphenols which have been introduced as antioxidant compounds. All geometry structures were optimized by M06-2X, MPWB1K with 6-311++G (d, p) basis in the gas phase and solvent using the CPCM model. Three probable mechanisms for the antioxidant activities have been presented and analyzed. According to bond dissociation enthalpy (BDE) and ionization potential (IP) values, hydrogen atom transfer (HAT) mechanism is a more reasonable path for antioxidant activity. The contribution of the HOMO-LUMO orbitals and spin density distribution have been calculated for evaluating of the previous data. Finally, based on the comparison of the experimental and the calculated data, BDE mechanism showed the best agr...
Scientific reports, 2018
Antioxidants are a diverse group of chemicals with proven health benefits and thus potential preventive medicine and therapeutic applications. While most of these compounds are natural products, determining their mechanism of radical scavenging and common motifs that contribute to antioxidant activity would allow the rational design of novel antioxidants. Here the origins of the antioxidant properties of ten natural products of the lignan family were studied in silico by calculating their thermochemical properties by using ROB3LYP/6-311++G(2df,2p)//B3LYP/6-311G(d,p) model chemistry. Three conditions were modelled: gas phase, ethanol and water solvents. The results allowed assigning the antioxidant activity to specific moieties and structural features of these compounds. It was found that the benzylic hydrogen atoms are the most likely to be abstracted to form radicals and hence define antioxidant properties in most of the studied compounds. The results also suggested that the most l...