Synthesis and antitumor activity of novel oleanolic acid-nitrate conjugates

A series of novel oleanolic acid-nitrate conjugates were synthesized by coupling nitrate with 3-OH of OA via various linkers, and their structures were determined by IR,MS and ¹H NMR. The cytotoxicity of the synthetic derivatives against human cancer cells SMMC-7721,BEL-7402,A549 and HT-29 was evaluated by MTT assay. Preliminary experimental results showed that compound 8c was the most potent one, whose cytotoxicity against A549,HT-29 and SMMC-7721 was stronger than that of the positive control adriamycin. Compound 8c is a promising compound worthy of further study.