Monoterpene interconversions: Metabolism of pulegone by a cell-free system from Mentha piperita

Cell-free extracts prepared from young vegetative shoot tips of Mentha piperita L. (peppermint) utilize 14C-labelled pulegone. Menthone, isomenthone, and menthol have been tentatively identified as products. NADPH2 is an essential cofactor. Anaerobic conditions enhance the yields of menthone and isomenthone, and menthol production has been observed only under anaerobic conditions. Preparation of active extracts requires anaerobic conditions, as well as the use of insoluble polyvinylpyrrolidone (polyclar AT) to remove phenolic materials, and gel filtration to remove endogenous substrate and any remaining phenolic materials. Extracts prepared by a similar procedure from M. arvensis L. and from M. sylvestris L. have been shown to reduce pulegone to menthone and isomenthone in the presence of NADPH2.