Microbial transformation of papaveraldine

Preparative-scale fermentation of papaveraldine (1), the known benzylisoquinoline alkaloid, with Mucor ramannianus 1839 (sih) has resulted in a stereoselective reduction of the ketone group and the isolation of S-papaverinol (2) and S-papaverinol N-oxide (3). The structure elucidation of both metabolites was based primarily on 1D-, 2D-NMR analyses and chemical transformations. The absolute configuration of 2 was determined using Horeau's method of asymmetric esterification. These metabolism results were consistent with the previous plant cell transformation studies on papaverine and isopapaverine.