The Metabolism of (R)-(+)-Pulegone, a Toxic Monoterpene

(R)-(+)-Pulegone is a major monoterpene constituent of pennyroyal oil, a mint oil obtained from the leaves of plants Mentha pulegiwn or Hedeoma pulegoides (1). Pennyroyal oil is widely used as a fragrance and flavoring agent (2), and has been used, based on folklore, as a herbal medicine to control menses and terminate pregnancy (3). The ingestion of large quantities of the oil has been associated with toxic effects (4–8), and hepatotoxicity observed in humans has been modeled in mice (9, 10) and rats (11, 12).