(−)-Carvone: Antispasmodic effect and mode of action

(−)-Carvone is a monoterpene ketone found in spearmint (Mentha spicata var. crispa) essential oil that is widely used as an odor and flavor additive. An intestinal antispasmodic effect was recently reported for (−)-carvone, and it has been shown to be more potent than its (+)-antipode. The mechanism of (−)-carvone action in the intestines has not been investigated. To gain a better understanding of the (−)-carvone antispasmodic effect, we investigated its pharmacological effects in the guinea pig ileum. Terminal portions of the ileum were mounted for isotonic contraction recordings. The effect of (−)-carvone was compared with that of the classical calcium channel blocker (CCB) verapamil. In isolated ileal smooth muscle, (−)-carvone did not produce direct contractile or relaxation responses and did not modify electrically elicited contractions or low K+-evoked contractions. The submaximal contractions induced by histamine (p < 0.001), BaCl2 (p < 0.05), and carbachol (p < 0.01) were significantly reduced by (−)-carvone. The contractile response elicited by high concentrations of carbachol was reduced but not abolished by (−)-carvone. No additive action was detected with co-incubation of (−)-carvone and verapamil on carbachol-induced contraction. (−)-Carvone reduced the contraction induced by high K+ and was almost 100 times more potent than verapamil. Thus, (−)-carvone showed a typical and potent CCB-like action. Many effects described for both (−)-carvone and spearmint oil can be explained as a CCB-like mode of action.

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