Biotransformation of monoterpenes by mentha cell lines: conversion of menthone to neomenthol.

Following previous results, which indicated that cell lines derived from different Mentha chemotypes were either capable or not capable to biotransform pulegone into isomenthone, we studied menthone biotransformation by in vitro cultured Mentha cell lines. All the six cell lines did transform (-)-menthone into another monoterpene. The latter was identified by GLC, TLC and NMR techniques as (+)-neomenthol. None of these cell lines reduced (+)-isomenthoneto the corresponding alcohol. These results indicate a stereospecificity in respect to both precursor and product in this plant cell biotransformation system.