The Structure-activity Relationships Of Triterpenoid Derivatives And The Antiproliferative Mechanism In BEL-7404 Cells

The development of anticancer drugs has become a major issue with the world’s cancer morbidity and mortality continues to increase.Nature products continue to play a highly significant role in the drug discovery and development.Many nature products have potential for using in cancer chemoprevention.Oleanolic acid(OA)and 18β-Glycyrrhetinic acid(GA)belong to the family of triterpenoids which have anti-tumor activity.In order to promote the effect of anti-proliferative and reduce toxicity to normal cells,40 kinds of derivatives had been synthesized,25 kinds of derivatives are soluble.In this study,we had examined the in vitro anti-cancer activity of the above 25 kinds of soluble derivatives through MTT.Then analyzed the structure-activity relationship.We also determined the most effective derivatives and the sensitive cancer cell lines.The cell lines used were liver cancer BEL-7404 and breast cancer MDA-MB-231.The normal liver cell line L-02 was used as the positive control,and taxol as the positive drug control.The result showed that compound 17,25,38 and 39 had stronger cytotoxicity against BEL-7404 and MDA-MB-231 cells.The compound 38 which had a nitrogen heterocycle group at the 2,3-position in the A ring had not been reported.It induced a marked concentration-dependent inhibition of BEL-7404 cell and MDA-MB-231 cell proliferation.The IC50 was 35 μMand 44.82μM respectively.It also had low cytotoxicity to the non-HCC L-02 cells,the IC50>160μM.To determine compound 38 and compound 39 induced apoptosis in cancer cells,nuclear morphology in BEL-7404 cells was analyzed using Hoechest 33258 staining.After treatment the cells revealed typical morphological apoptotic characteristics.These studies indicated that these derivatives of OA had high cytotoxicity and may induce apoptosis in cancer cells.The results from Western blot analysis showed that the compound 38 and compound 39 were able to down-regulate the level of Bcl-2 and up-regulate the level of Bax,then the cytochrome e was released into the cytosol.They also acted in a time-dependent manner and resulted in activation of caspase-3 and caspase-9.The flow cytometric assay was performed after propidium iodide(PI)staining of BEL-7404 following compound 38 and compound 39 treatmented for 24h.The results showed that compound 38 and compound 39 in dose-dependent manner increased the G0/G1 population.BEL-7404 cell cycle was arrested at G0/G1 phase.All these works above made some preparation for further structural modification of glycyrrhetic acid and oleanolic acid,and paved the way to discover new anticancer drugs.