Modified Monoterpenes from Biotransformation of (-)-Isopiperitenone by Suspension Cell Culture of Mentha piperita

The biotransformation of (-)-(4R)-isopiperitenone (1) by suspension cell culture of Mentha piperita yielded three new hydroxylated derivatives, 4-6, and two new epoxidized derivatives, 7 and 8. (-)-7-Hydroxyisopiperitenone (2) and its glucoside were previously isolated from the culture. The structures of 4-8 were elucidated using spectral methods, and their absolute stereochemistry was established by NMR experiments and correlation with compounds of known configuration.