Microbial transformation of icariin and its derivatives.

Microbial transformation is an important tool to perform selective conversion of compounds to derivatives which are difficult to produce synthetically. In order to obtain icariside II and icaritin, the active components in Herba Epimedii , biotransformation studies using microbes as biocatalysts were carried out. Icariside II () and icaritin () were produced through biotransformation of icariin () using the fungi and var. in 98% and 92% yields, respectively. In the subsequent transformation studies, was deglycosylated to form by , whereas was further converted to a novel compound icaritin-3--β-d-glucopyranoside () and previously known icaritin-3,7--β-d-diglucopyranoside () by . Biological evaluation of these compounds using MTT assay exhibited potent cytotoxic activities against human cancer cell lines A549, A375P, and MCF-7, with icariin being the most active, indicating that glycosylation plays a role in the cytotoxic activity.