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 α-hydroxylation product, methyl 2α-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 α-hydroxylation of lupane-type pentacyclic triterpenes.