A cytotoxic agent from Strychnos nux-vomica and biological evaluation of its modified analogues

Although a number of chemicals have been isolated from Strychnos nux-vomica, only a few have been evaluated for their biological significance. As a part of our drug discovery programme for cytotoxic agents from Indian medicinal plants, a novel cytotoxic agent, loganin 1 was isolated from the fruit pulp of S. nux-vomica. The loganin 1 showed significant anticancer activity against the human liver (WRL-68), colon (COLO-320 and CaCo2), ovarian (PA-1) and breast (MCF-7) cancer cell lines. Loganin 1 was further chemically transformed into eleven semi-synthetic derivatives 2–12 of which 2′,3′,4′,7-tetra-O-acetyl-6′-O-(3′′′, 4′′′, 5′′′)-trimethoxybenzoyl loganin 11 and 2′,3′,4′,7-tetra-O-acetyl-6′-O-lauroyl loganin 6 derivatives showed eight, 13 and three times while 2′,3′,4′,7-tetra-O-acetyl-6′-O-lauroyl loganin 6 showed equal, 13 and two times more activity against human suspension colon (CaCo2), adherent colon (COLO-320) and liver (WRL-68) cancer cell lines, respectively, than the known anticancer agent, vinblastine. The other analogues (except 4, 8 and 9) and loganin also showed marginal to moderate anticancer activity against the five tested human cancer cell lines.