Chemical constituents and anti-tubercular activity from the root of Styrax formosana

Styrax formosana (Styracaceae) is a shrub or small tree, endemic to Taiwan and grows from low to medium altitudes throughout the Island. There are about 60 species of Styrax widely distributed in the Mediterranean region, Eastern Asia, North and South America. Only one study reported the leaves' extract of this plant showing free radical scavenging activity, but its chemical constituents have not been studied. Methanolic extract of the root from this species showed anti-tubercular activity against Mycobacterium tuberculosis H37Rv in vitro. Therefore, the aim of this study is the isolation of chemical constituents and the evaluation of their anti-tubercular activity. The methanolic extract of the root from S. formosana was partitioned into n-butanol-soluble and water-soluble layers, only n-butanol-soluble layer showed anti-tubercular activity. Bioassay-guided fractionation of the active n-butanol-soluble layer of the root led to the isolation of eleven known compounds so far including four triterpenoids, oleanolic aldehyde acetate (1), erythrodiol-3-acetate (2), oleane-11,13(18)-dien-28-oic acid-3-acetate (6), and oleanolic acid-3-acetate (8); four lignans, styraxin (5), piperitol (7), sesamin (10), and matairesinol (11); three steroids, β-sitosterol (3), stigmasterol (4), and α-spinasterol (9). These structures were elucidated using detailed spectroscopic method, mainly NMR spectroscopy together with ESIMS analysis.

Keywords: Styrax formosana, Styracaceae, Root, Anti-tubercular