Antitubercular activity of triterpenoids from Asteraceae flowers

Twenty-eight 3-hydroxy triterpenoids of taraxastane- (1-7), oleanane- (8-12), ursane- (13-15), lupane- (16,18,19), taraxane- (20), cycloartane- (21-25), tirucallane- (26-28), and dammarane-types (29) isolated from the non-saponifiable lipid fraction of the flower extract of chrysanthemum (Chrysanthemum morifolium) and one lupane-type 3alpha-hydroxy triterpenoid (17) derived from 16 were tested for their antitubercular activity against Mycobacterium tuberculosis strain H37Rv using the Microplate Alamar Blue Assay (MABA). Fifteen compounds showed a minimum inhibitory concentration (MIC) in the range of 4-64 microg/ml, among which maniladiol (9; MIC 4 microg/ml), 3-epilupeol (17; 4 microg/ml), and 4,5alpha-epoxyhelianol (27; 6 microg/ml) exhibited the highest activity. Cytotoxicity of compound 17 against Vero cells gave an IC50 value of over 62.5 microg/ml, suggesting some degree of selectivity for M. tuberculosis.