Direct microbial-catalyzed asymmetric α-hydroxylation of betulonic acid by Nocardia sp NRRL 5646

Microbial transformation of betulonic acid by Nocardia sp. NRRL 5646 in preparative scale resulted in the isolation of one unexpected asymmetric alpha-hydroxylation product, methyl 2 alpha-acetoxy-3-oxo-lup-20(29)-en-28-oate, and one known compound methyl 3-oxo-lup-20(29)-en-28-oate. The structures of metabolites were elucidated unambiguously by ESI-MS, 2D-NMR spectroscopy. This is the first successful microbial transformation of ketone alpha-hydroxylation of lupane-type pentacyclic triterpenes. (C) 2009 Elsevier Ltd. All rights reserved.