Biotransformation of cinobufagin by Cunninghamella elegans.

Cunninghamella elegans has been employed for the biotransformation of cinobufagin to afford 5 metabolites. The structures of the transformation products have been characterized as 12alpha-hydroxybufagin, 11alpha-hydroxybufagin, 12beta-hydroxy-desacetylcinobufagin, 3-oxo-12alpha-hydroxybufagin and 12beta-hydroxybufagin. Products 12alpha-hydroxybufagin and 11alpha-hydroxybufagin are new compounds. In vitro both the biotransformation products and cinobufagin all showed cytotoxic activities against HeLa cells.