Comparative Study of Antioxidant Properties and Cytoprotective Activity of Flavonoids

A. I. Potapovich and V. A. Kostyuk^*

School of Biology, Belorussian State University, pr. F. Skoriny 4, Minsk 220050, Belarus; fax: 375 (172) 77-5535; E-mail: kostyuk@bsu.by

^* To whom correspondence should be addressed.

Received February 14, 2002; Revision received May 15, 2002

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Antioxidant properties and cytoprotective activity of flavonoids (rutin, dihydroquercetin, quercetin, epigallocatechin gallate (EGCG), epicatechin gallate (ECG)) were studied. All these compounds inhibited both NADPH- and CCl₄-dependent microsomal lipid peroxidation, and the catechins were the most effective antioxidants. The I₅₀ values calculated for these compounds by regression analysis were close to the I₅₀ value of the standard synthetic antioxidant ionol (2,6-di-tert-butyl-4-methylphenol). The antiradical activity of flavonoids to O₂^-* was studied in a model photochemical system. Rate constants of the second order reaction obtained by competitive kinetics suggested flavonoids to be more effective scavengers of oxygen anion-radicals than ascorbic acid. By competitive replacement all flavonoids studied were shown to be chelating agents capable of producing stable complexes with transition metal ions (Fe²⁺, Fe³⁺, Cu²⁺). The flavonoids protected macrophages from asbestos-induced damage, and the protective effect increased in the following series: rutin < dihydroquercetin < quercetin < ECG < EGCG. The cytoprotective effect of flavonoids was in strong positive correlation with their antiradical activity to O₂^-*.

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KEY WORDS: antioxidants, flavonoids, oxidative stress, reactive oxygen species, asbestos, rutin, quercetin, epicatechins

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