Anxiolytic-like effect of Illicium verum fruit oil, trans-anethole and related compounds in mice.

The fruit of Illicium verum Hook. f. (star anise) is used by many as a spice. The fragrance of I. verum fruit is characteristically anise-like. In this study, hexane-extracted I. verum fruit oil (IVO), trans-anethole as the main component, and related compounds (propiophenone, 4'-methoxy-propiophenone, trans-β-methylstyrene) were analyzed in order to clarify the emotional effect of inhaling the fragrance of I. verum fruit. As a result, although 4 μL/L air IVO did not exhibit an anxiolytic-like effect, 1 μL/L air trans-anethole exhibited a significant effect (p < 0.05). Moreover, the anxiolytic-like effect of 1 μL/L air trans-anethole was significantly greater than 1 μL/L air propiophenone and 1 μL/L air 4'-methoxy-propiophenone (p < 0.05). Thus, the anxiolytic-like effect of trans-anethole was confirmed, and it is proposed that the methoxyl group and 1-propenyl group in the para position of the benzene ring are necessary for the effect.