Pulegone (IUPAC: (R)-(+)-p-menth-8-en-3-one; CAS 89-82-7) belongs to the monoterpenoid ketone subclass of terpenes. Its molecular formula is C10H16O and it carries a cyclohexanone ring with an isopropenyl substituent, giving it a structure closely related to other menthane-framework compounds such as menthone and carvone. The (R)-(+) enantiomer predominates in most natural sources and is the form most studied in laboratory settings.
In nature, pulegone occurs at high concentrations in Mentha pulegium (pennyroyal), where it can constitute 60–90% of the essential oil by GC analysis, and at lower but appreciable levels in some cultivars of Mentha × piperita (peppermint) and Mentha spicata (spearmint). It also appears in Nepeta spp. (catmints) and various other members of the mint family (Lamiaceae). Trace amounts have been detected in certain Bulia and Calamintha species. Biosynthetically, pulegone sits along the menthol pathway, formed from pulegone reductase acting on (+)-pulegone; it can further reduce to menthone and ultimately to the cooling alcohol menthol.
Pulegone carries a pronounced, penetrating odour described variously as minty, camphoraceous, slightly woody, and herbaceous. These aroma characteristics make it of commercial interest to the flavour and fragrance industry, though its use in food and cosmetics is regulated in several jurisdictions due to toxicological considerations at high doses; the European Food Safety Authority (EFSA) completed a re-evaluation of pulegone as a flavouring substance in 2013, identifying a margin-of-exposure concern at higher intake levels. In Australia, flavouring substances including pulegone are assessed against the relevant Schedule of the Australia New Zealand Food Standards Code administered by Food Standards Australia New Zealand (FSANZ).
Preliminary laboratory research has investigated pulegone's chemistry and its interactions with various biological systems at the cellular level; results are exploratory and cannot be extrapolated to claims about human health outcomes. No regulatory authority has approved pulegone as a therapeutic agent, and the compound is not listed in the Australian Register of Therapeutic Goods (ARTG) as an active ingredient in any approved medicine. Researchers noting hepatotoxic effects in rodent studies at high doses have flagged the importance of dose-dependent risk assessment when pulegone is present in botanical preparations.
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