Aromatic-Substituted Ursolic Acid Derivatives:Design,Synthesis,and Antitumor Effect

ObjectiveUrsolic acid and its derivatives show great potentiality in antitumor.Our previous study on structural modification of ursolic acid revealed that the NO-donor ursolic acid derivatives with aromatic substitution at the C2-position had remarkable anti-proliferation activity on HT-29 colon cancer cells.In this study,we synthesized more NO-donor ursolic acid derivatives,by modifying the C-2 position with different aromatic groups,and examined their anti-tumor activities.MethodsUrsolic acid derivatives were synthesized by oxidation,condensation,nucleophilic substitution and reduction reaction.The derivatives were purified by column chromatography,and their structures were identified by NMR,IR and LC-MS spectrometry.The anti-proliferative effect of derivatives on human liver cancer HepG-2 cells,human breast cancer MCF-7 cells,human colon cancer HT-29 cells,human lung cancer A549 cells and human cervical cancer Hela cells was detected by MTT assay.The antitumor effect of compound 2-(4-pyridylmethylidene)-3-carbonylursolic acid-(2-nitrooxyethyl)ester(5m)on HT-29 cells was investigated by Cell cycle detection,apoptosis rate detection,mitochondrial membrane potential detection,ROS reactive oxygen level detection,and DAPI and AO/EB fluorescence staining.5m was also subjected to docking studies with Bcl-2 and Caspase 8 proteins and their interaction modes were analyzed.ResultsIn our continuing reasearch,27 ursolic acid derivatives were synthesized and their structures were confirmed.The anti-proliferation results in vitro showed that the compound 5m displayed good inhibitory effects to human lung cancer cells A549,breast cancer cells MCF-7,hepatocellular carcinoma cells HepG-2,colon cancer cells HT-29,and cervical cancer cells Hela.The lower IC50 value is 7.42±0.51 μM on breast cancer cells MCF-7.The results of flow cytometry and fluorescence microscopy showed that 5m exerted antitumor effects by inducing MCF-7 cells to apoptosis and causing cell cycle arrest.ConclusionThe derivative 5m was more efficient in its inhibitory activity than ursolic acid.And the experiments have confirmed that 5m can induce MCF-7 cell apoptosis and inhibit cell proliferation in vitro.Therefore,5m is expected to be a promising broad-spectrum of anticancer candidate.