Studies On The Antitumor Activity Of Some Naturally Occurring Triterpenoids

The antitumor activities of 48 naturally occurring triterpenoids of 6 classes and two extracts were examined in order to find effective anticancer agents with low toxicity and provide leading compounds for new drug research and development. The mechanism and QSAR of some triterpenoids were studied and summarized so that to provide theoretic foundation for pharmacodynamic research and new drug searching.Firstly, the cytotoxicity of the triterpenoids was investigated on several cancerous cell lines including solid tumor, leukemia, drug resistant tumor (R-HepG2) and primary cultured normal mouse hepatocytes for screening effective antineoplastic agents against both drug-sensitive and drug-resistant tumor with reduced toxicity. Evident cytotoxicity of UA, BA, C.dah, C.foe, C.dah 1-3 and Cfoe-1 on all tested neoplastic cell lines revealed that they were effective on both drug-resistant tumor and drug-sensitive tumor. Furthermore, they all showed relatively selective cytotoxicity on cancerous cells based on the higher IC50 values of them on normal cells than that on tumor cells. In addition, although Kal A, Kal I, Sch. and Isosch. possessed cytotoxicity, structure modification was needed because lack of selectivity of them.Morphological observation, DNA ladder and cell cycle analysis were employed to elucidate the cytotoxic mechanism of some promising triterpenoids on cell level. Cell death can occur by either of two distinct mechanisms, necrosis or apoptosis. UA, BA, OA, GA, C.dah, C.foe, C.dah 1-3 and C.foe-1 brought out similar apoptotic morphological changes on HepG2 and HL-60 cell lines (experiment of C.foe-1 has not...