A detail study of the polarographic reduction of genistein in aqueous medium from pH1 to pH12 is presented. Over the entire pH range, four reduction waves have been achieved. In the alkaline medium, the reactant is strongly absorbed, so that the reaction is of a surface nature. In acidic media, an irreversible reduction process of genistein molecule involving two electrons and one proton takes place. Whereas an irreversible reduction process of anion of genistein involving two electrons and one proton takes place from ph5 to pH10, the reduction is also controlled by the prior protonation reaction of genistein. When pH〉6, there are two irreversible reduction waves corresponding to the reduction of two different anions of genistein, and one of them belongs to adsorption pre-wave. But both of them involve two electrons and one proton. Also, the pure genistein obtained from soybeans was determined by first order derivative polargraphy and it was validated by parallel determination using UV. In particular, its scavenging effecton superoxide anion radical was studied by the auto-oxidation of pyrogallol in HCl-tris buffer (pH=8.2) in order to explain its peculiar biological effects.

Key words: ANTICARCINOGEN, POLAROGRAPHIC ANALYSIS, REDUCTION, FREE RADICALS