Metabolites of the fungistatic agent 2β-methoxyclovan-9α-ol by Macrophomina phaseolina.

Biotransformation of 2β-methoxyclovan-9α-ol (1), a fungistatic agent against Botrytis cinerea, was investigated with Macrophomina phaseolina. Demethoxylation, regioselective oxidation at C-9 and C-13, and inversion of the configuration at C-9 of compound 1 afforded six oxidative metabolites, 2β-methoxyclovan-9-one (2), clovan-2β,9β-diol (3), clovan-2β,9α-diol (4), clovan-2β,13-diol-9-one (5), 2β-methoxyclovan-9α,13-diol (6), and clovan-2β,9β,13-triol (7). Compounds 5-7 are described here for the first time, and their structures were deduced by different spectroscopic techniques. The antifungal activity of new metabolites 5-7 was also evaluated against B. cinerea.