Terpene biosynthesis. Part IV. Biosynthesis of (+)-pulegone in Mentha pulegium L.

Abstract

Feeding of 3,3-dimethyl[1-¹⁴C]acrylic acid to Mentha pulegium L. led to a tracer pattern in (+)-pulegone [p-menth-4(8)-en-3-one] that indicated extensive degradation of the additive and probable incorporation as acetate units. A previous report of intact incorporation of the acid could not be substantiated.

[2-¹⁴C] Mevalonic acid was incorporated into (+)-pulegone to give asymmetric labelling whereby almost all the tracer was associated with the isopentenyl pyrophosphate portion. The pattern also showed that if (as is believed on the basis of time-incorporation studies) terpinolene [p-mentha-1,4(8)-diene] was a precursor of pulegone, oxidation at the two positions α to the exocyclic double bond occurred at comparable rates.