New Tryptophan Metabolites from Cultures of the Lipophilic Yeast Malassezia furfur

Eleven new indole alkaloids were isolated from cultures of the human pathogenic yeast Malassezia furfur after addition of L-tryptophan as the sole N-source: pityriacitrin B (2), the malassezindoles A (3) and B (4), malassezialactic acid (6), the malasseziazoles A (7), B (8), and C (9), pityriazole (10), malasseziacitrin (11), and malassezione (12), along with the known d-indole-3-lactic acid (=(αR)-α-hydroxy-1H-indole-3-propanoic acid 5), and 2-hydroxy-1-(1H-indol-3-yl)ethanone (13). The structural elucidation of these compounds was performed by spectroscopic methods (MS as well as 1D- and 2D-NMR). The biogenetic relationships (Scheme) and biological activities of the new metabolites are discussed.