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首页> 外文期刊>Kinetics and catalysis >Antioxidant activity of chalcones: The chemiluminescence determination of the reactivity and the quantum chemical calculation of the energies and structures of reagents and intermediates
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Antioxidant activity of chalcones: The chemiluminescence determination of the reactivity and the quantum chemical calculation of the energies and structures of reagents and intermediates

机译：查耳酮的抗氧化活性：化学发光测定反应活性以及试剂和中间体的能量和结构的量子化学计算

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摘要

Six antioxidants from the class of chalcones (ArOH), compounds from which flavonoids are obtained in nature, were studied. The antiradical activity of chalcones and a number of related compounds was determined by a chemiluminescence method using the scavenging of peroxide radicals ROO center dot + ArOH -> ROOH + OAr center dot (with the rate constant k (7)) in a model reaction of diphenylmethane (RH) oxidation. The structures and energies of the reagents and intermediates were determined by semiempirical quantum chemical (PM3, PM6) calculations. 3,4-Dihydroxychalcone and caffeic acid, which have a catechol structure, that is, two neighboring OH groups in phenyl ring B, exhibited high antioxidant activity (k (7) a parts per thousand 10(7) l mol(-1) s(-1)); this is consistent with the lowest bond strengths D(ArO-H) of 79.2 and 76.6 kcal/mol, respectively. The abstraction of a hydrogen atom by the ROO center dot radical is the main reaction path of these compounds; however, the low stoichiometric coefficients of inhibition (f = 0.3-0.7) suggest a contribution of secondary and/or side reactions of ArOH and OAr center dot. In the other chalcones, the ArO-H bond is stronger (D(ArO-H) = 83-88 kcal/mol) and the antioxidant activity is lower (k (7) = 10(4)-10(5) l mol(-1) s(-1)).
机译：研究了查尔酮（ArOH）类中的六种抗氧化剂，这些化合物是从自然界中获得类黄酮的化合物。查耳酮和许多相关化合物的抗自由基活性是通过化学发光法使用过氧化物自由基ROO中心点+ ArOH-> ROOH + OAr中心点（速率常数为k（7））清除而确定的。二苯甲烷（RH）氧化。试剂和中间体的结构和能量通过半经验量子化学（PM3，PM6）计算确定。具有邻苯二酚结构的3,4-二羟基查耳酮和咖啡酸，即苯环B中的两个相邻的OH基团，具有很高的抗氧化活性（k（7）a千分之10（7）l mol（-1） s（-1））;这与分别为79.2和76.6 kcal / mol的最低结合强度D（ArO-H）相一致。 ROO中心点自由基夺取氢原子是这些化合物的主要反应路径。但是，低的化学计量抑制系数（f = 0.3-0.7）表明ArOH和OAr中心点的次级和/或副反应的贡献。在其他查耳酮中，ArO-H键更强（D（ArO-H）= 83-88 kcal / mol），抗氧化活性较低（k（7）= 10（4）-10（5）l mol （-1）s（-1））。

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