Isopulegol (molecular formula C10H18O) is a monocyclic monoterpenoid of the p-menthane family. It exists as multiple stereoisomers, of which (−)-isopulegol is the most prevalent in nature. The compound carries a secondary allylic alcohol group and an isopropenyl side chain, giving it a characteristic cool, mint-like, slightly green scent profile that is distinct from , though related to , pulegone and menthol.
In the plant kingdom, isopulegol occurs most notably in Pelargonium species (scented geraniums), lemongrass (Cymbopogon citratus), pennyroyal (Mentha pulegium), and various Eucalyptus species native to Australia. It is a biosynthetic precursor to menthol via enzymatic hydrogenation, a pathway studied in detail within the Lamiaceae family. The compound is also detected at trace levels in cannabis (Cannabis sativa) essential oil fractions, where it contributes to the broader terpene profile alongside more dominant constituents such as myrcene and linalool.
In flavour and fragrance science, isopulegol is used as a reference standard and minor ingredient in aroma compositions. Its cooling sensation, though less pronounced than menthol, has made it a subject of laboratory interest; in vitro and preclinical studies have examined its interactions with TRPM8 cold-receptor channels and with GABAA receptor systems. These findings remain preliminary , conducted primarily in cell-culture and rodent models; and no conclusions about human physiological effects can be drawn from the current evidence base.
Isopulegol is classed as a Generally Recognised as Safe (GRAS) flavouring substance by the Flavour and Extract Manufacturers Association (FEMA) at levels consistent with its natural occurrence in food. It is not a scheduled substance under Australia's Poisons Standard (the Standard for the Uniform Scheduling of Medicines and Poisons) and does not require regulatory authorisation for use as a cosmetic or food-flavouring ingredient within approved concentration limits.
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