Microbial transformations of halolactones with p-menthane system.

Biologically active piperitone-derived racemic iodo-, bromo- and chlorolactones (1-3) were transformed with the use of microbial enzymatic systems. Four strains of filamentous fungi Absidia glauca AM254, Absidia cylindrospora AM336, Mortierella vinaceae AM149 and Nigrospora oryzae AM8 transformed halolactones (1-3) to four new halohydroxylactones (4-7). In all biotransformations the hydroxy group was incorporated in inactivated methine carbon atom at isopropyl substituent. In N. oryzae AM8 culture the bromolactone with additional hydroxy group in α-position, relative to CO bond in γ-lactone ring, was also formed as a product. The structures of new compounds were established on the basis of spectral data.