Enzymatic synthesis of tryptamine and its halogen derivatives selectively labeled with hydrogen isotopes

Nine isotopomers of tryptamine and its halogen derivatives, labeled with deuterium, tritium in side chain, i.e., [(1R)-(2)H]-, [(1R)-(3)H]-, 5-F-[(1R)-(2)H]-, 5-F-[(1R)-(3)H]-, 5-Br-[(1R)-(2)H]-, double labeled [(1R)-(2)H/(3)H]-, 5-F-[(1R)-(2)H/(3)H]-, and ring labeled [4-(2)H]-, and [5-(2)H]-tryptamine, were obtained by enzymatic decarboxylation of l-Trp and its appropriate derivatives in deuteriated or tritiated media, respectively. Intermediates: [5′-(2)H]-l-Trp used for further decarboxylation was synthesized by enzymatic coupling of [5-(2)H]-indole with S-methyl-l-cysteine, and [4′-(2)H]-l-Trp was obtained by isotope exchange (1)H/(2)H of the authentic l-Trp dissolved in heavy water induced by UV-irradiation. Doubly labeled [(1R)-(2)H/(3)H]- and 5-F-[(1R)-(2)H/(3)H]-tryptamine were obtain by decarboxylation of l-Trp or [5′-F]-l-Trp carried out in (2)H(3)HO incubation medium.