Interaction of anthralin with cysteine: a new entry into the chemistry of biologically active anthrones.

Abstract Evidence is reported that under physiological conditions anthralin (I), an antipsoriatic drug , reacts with cysteine to give an ether-insoluble adduct which was formulated as 1,8-dihydroxy-10-(2-amino-2-carboxyethylthio)-9-anthrone (III) by model studies and unambiguous synthesis.