Biotransformation and Phylogeny: VI. Microbial Oxidation of Aristolenepoxide to Phytotoxins

Main metabolites of the microbial oxidation of (6R)-aristolenepoxide are 5α-, 9β-, 10β-, and 15-hydroxy-aristolenepoxide. Aristolene-7,14-oxide-6α-ol was also formed. Some of them showed modest phytotoxic activity in the cress test, where 9β-hydroxy-aristolenepoxide is the most active one. The actvity of the strains mirrored their phylogenetic positions. Bacteria were most active in oxidizing 15-hydroxy-aristolenepoxide to the aldehyde, while fungi, especially Basidiomycotina, were more active in the hydroxylation of the substrate than bacteria.