Preparation, characterization, and antiviral activity of microbial metabolites of stemodin.

Screening studies for microbial transformation products of stemodin [2] have identified a number of microbial metabolites. Scale-up fermentation with Rhizopus arrhizus ATCC 11145 and Streptomyces sp. NRRL 5691 have resulted in the production of five metabolites that have been characterized with the use of 2D nmr and X-ray techniques. These metabolites have been identified as 18-hydroxystemodin [6], 16,18-dihydroxystemodin [7], 8 beta-hydroxystemodin [8], 8 beta, 18-dihydroxystemodin [9], and 7 beta, 8 beta-dihydroxystemodin [10]. The antiviral activity and cytotoxicity of the isolated metabolites have been evaluated.