Abstract:
In a search for bioactive compounds of Sphaeranthus africamus Linn., chloroform and butanol crude extracts revealed high cytotoxicity against brine shrimp (Artemia salina Linn.) and various carcinoma cell lines. The separation of two active fractions led to the isolation of nine compounds : fridelan-3β-ol, mixture of steroids, 2-O-n-buthyl-β-fructopyranose, quercetagetin-3,6,7-trimethyl ether, quercetagetin-3,3’,7-trimethyl ether, quercetagetin-3,7-dimethyl ether, quercetin, 3α,-5β-diangeloxoyloxy-7-hydroxycarvotacetone and 2,4 α, 6β triangeloxoyloxy-5-(sec-propyl)-2-cyclohexenone (carvotacetone analogue). The last two compounds were found to be new compounds. The bioassay result indicated that both flavonoids and carvotacetone derivatives showed biological activities. Quercetagetin-3,6,7-trimethyl ether, quercetagetin-3,3’,7-trimethyl ether quercetagetin-3,7-dimethyl ether and quercetin inhibited cAMP at dose 10mg/ml with percentage inhibition of 75%, 50%, 42% and 87.5%, respectively. The 3α,5β-diangeloxoyloxy-7-hydroxycarvotacetone and 2,4α, 6β triangeloxoyloxy-5-(sec-propyl)-2-cyclohexenone showed cytotoxicity against brine shrimp with LC50 of 11.45 and 12.34 ug/ml, respectively.
