A reinvestigation of the anaerobic conversion of adrenochrome to adrenaline black

In contrast to previous work, which suggested that adrenaline black, derived from adrenochrome under acid conditions, was a 3,4-linked polymer of 1-methyl-5,6-dihydroxyindole, two 2,3'-linked indole dimers (I, R = R1 = H; RR1 = bond) and a 4,7'-3',3''-linked trimer (II) have now been isolated. In the light of these results the transformation of adrenochrome to adrenaline black appears to be an uncorrected model for the study of melanogenesis