Resorcinols, flavonoids, and stilbene phenols - Redox, radicals, and physiological effects

Abstract

There have been appreciable numbers of reviews on the biological properties of monophenols, catechols, and hydroquinones. However, the resorcinol class has received less attention. This review deals with the parent resorcinol, alkyl derivatives, resorcinol-containing stilbenes, and flavonoids, with an emphasis on their antioxidant and prooxidant effects. The apparent dichotomy is rationalized. In relation to antioxidant action, the phenols behave as donors of electrons or hydrogen atoms. As prooxidants, oxidation yields catechols or hydroquinones which are converted to electron transfer quinones. Subsequent redox cycling produces reactive oxygen species (ROS) which can result in beneficial effects or toxicity. The physiological responses are provided along with integration into the unifying mechanistic theme of electron transfer-ROS-oxidative stress. The multifaceted approach is unique in providing novel insight.