New sesquiterpene derivatives and anti-inflammatory constituents from Pachira aquatica
Pachira aquatica Aublet (Bombacaceae) is an evergreen tree, distributed in tropical America and introduced to Guangdong, Yunnan, and Taiwan as a cultivated plant . Cadinane sesquiterpenoids, sesquiterpene lactones, and triterpenes are widely distributed in plants of the family Bombacaceae, and many of these compounds exhibit antiangiogenic, hypotensive, and antimicrobial activities. Investigation of n-hexane-soluble fraction of the stem of P. aquatica has led to the isolation of two new sesquiterpene derivatives, 11-hydroxy-2-O-methylhibiscolactone A (1) and O-methylhibiscone D (2), together with 18 known compounds, including 5-hydroxyauranetin (3), kaempferol-3,7,4'-trimethyl ether (4), santi-7-methyl ether (5), 3,5,6,7,8,3',4'-heptamethoxyflavone (6), calycopterin (7), retusin (8), 5,4'-dihydroxy-3,7-dimethoxyflavone (9), isohemigossylic acid lactone-7-methyl ether (10), hibiscolactone A (11), hibiscone C (12), hibiscone D (13), 2-O-methylisohemigossypolone (14), scopoletin (15), benzophenone (16), 2α,3β-dihydroxylupene (17), lupenone (18), 24-methylenecycloartenol (19), and (23E)-cycloart-23-ene-3β,25-diol (20). The structures of new compounds 1 and 2 were determined through spectroscopic and MS analyses. Among the isolates, 5-hydroxyauranetin (3) and isohemigossylic acid lactone-7-methyl ether (10) exhibited potent inhibition against N-formyl-L-methionyl-L-leucyl-L-phenylalanine-induced superoxide production with IC50 values of 28.84±2.26 and 12.77±2.48µM, respectively.
Acknowledgement: This research was supported by grants from the National Science Council of the Republic of China (NSC 95–2320-B-127–001-MY3 and NSC 98–2320-B-127–001-MY3), awarded to Prof. J.-J. Chen.
References: 1. Tang Y et al. (1995) 'Bombacaceae' in 'Flora of China', Science Press, Beijing, China. Vol. 12, pp. 264–299