[Free radical mechanism of homogentisic acid in alkaptonuria].

Non-enzymatic oxidation in alkaline media of homogentisinic acid, excreted with urine in alkaptonuria, involved free radical mechanism. The oxidative process was accompanied by production of superoxide anion O2- and required metal cations. Free radical destruction of cells and biopolymers via O2- or homogentisinic acid semiquinone appears to be one of pathogenetic mechanisms responsible for impairment of connective tissue structures in patients with alkaptonuria.