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Antimicrobial Terpenoids from Elephantopus mollis

Consolacion Y. Ragasa,1 Agnes B. Alimboyoguen, 2 and Chien-Chang Shen, 3
1,2 Chemistry Department, De La Salle University, 2401 Taft Avenue, Manila 1004, Philippines, Division of Medicinal Chemistry, 3 National Research Institute of Chinese Medicine, 155-1, Li-Nong St., Sec. 2, Taipei 112, Taiwan

ABSTRACT

The leaves of Elephantopus mollis HBK, commonly known as malatabako is reported to exhibit antimicrobial properties. The study was conducted to isolate the dichloromethane soluble constituents of the plant which may contribute to this activity. The air-dried leaves of E. mollis afforded molephantin (1), molephantinin (2), 2-deethoxy-2-hydroxyphantomolin (3), stigmasterol (4), α-amyrin fatty acid ester (5a), and lupeol fatty acid ester (5b). The structures of the sesquiterpenes (1-3) were elucidated by extensive 1D and 2D NMR spectroscopy and confirmed by comparison of their 13C NMR data with those found in the literature, while the structures of 4, 5a, and 5b were deduced by comparison of their 1H and 13C NMR spectral data with those reported in the literature. Antimicrobial tests on 1-3 indicated that they are moderately active against the fungus, C. albicans and slightly against the bacteria: E. coli and P. aeruginosa and the fungus, T. mentagrophytes. Compounds 1 and a mixture of 1 and 2 exhibited slight activity against S. aureus, while 3 and a mixture of 1 and 2 were slightly active against B. subtilis. All compounds were found inactive against A. niger.

Keywords: Elephantopus mollis,  Asteraceae, molephantin, molephantinin, 2-deethoxy-2-hydroxyphantomolin, α-amyrin fatty acid ester, lupeol fatty acid ester, antimicrobial

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