Characterisation of 1,4-benzothiazine intermediates in the oxidative conversion of 5-S-cysteinyldopa to pheomelanins

Article abstract of DOI:10.1016/S0040-4039(00)73434-4

Under biologically relevant conditions, oxidation of 5-S-cysteinyldopa (1) pheomelanins proceeds through the formation of the 1,4-benzothiazine 7 along with the 3-carboxy analogue 6 in much smaller amounts, as evidenced by isolation of the reduced forms 5 and 4 and by deuterium labelling experiments.