5-Lipoxygenase Inhibition of the Fructus of Foeniculum vulgare and Its Constituents

The fruits of Foeniculum vulgare (Foeniculi Fructus) have been widely used in Chinese medicine as an antiemetic, ameliorating stomach ailments and as an analgesic. In order to establish its potential for antiallergic use, inhibitory actions of the fruit on 5-lipoxgenase (5-LOX) and ${\beta}$-hexosaminidase release were evaluated. The 70% ethanol extract of this plant material (FR) considerably inhibited 5-LOX-catalyzed leukotriene production from A23187-induced rat basophilic leukemia (RBL)-1 cells. The $IC_{50}$ was $3.2{\mu}g/ml$. From this extract, 12 major compounds including sabinene, fenchone, ${\gamma}$-terpinene, ${\alpha}$-pinene, limonene, p-anisylacetone, panisylaldehyde, estragole (4-allylanisole), trans-anethole, scopoletin, bergapten and umbelliferone were isolated. And it was found that several terpene derivatives including ${\gamma}$-terpinene and fenchone as well as phenylpropanoid, trans-anethole, showed considerable inhibitory action of 5-LOX. In particular, the $IC_{50}$ of trans-anethole was $51.6{\mu}M$. In contrast, FR and the isolated compounds did not show considerable inhibitory activity on the degranulation reaction of ${\beta}$-hexosaminidase release from antigen-treated RBL-2H3 cells. Against arachidonic acid-induced ear edema in mice, FR and trans-anethole showed significant inhibition by oral administration at doses of 100-400 mg/kg. In conclusion, FR and several major constituents are 5-LOX inhibitors and they may have potential for treating 5-LOX-related disorders.