Synthesis of novel diterpenoid analogs with in-vivo antitumor activity.

A lead compound 7 has antitumor effect, which was discovered by screening our small synthetic natural product-like compound (NPL) library. Based on the lead compound, a series of novel tricyclic diterpene analogs were synthesized and investigated for their activity against the growth of various tumor cell lines using the sulforhodamine B (SRB) assay. To our delight, most aromatic amide compounds exhibited more potent antitumor activity than the lead compound. The most active compound 19 (QW30) showed an average IC50 0.33 µM, which was 15-fold more potent than the lead compound. Most of the compounds with potent antitumor activity displayed less toxic on normal human fibroblasts (HAF) in comparison with the tumor cell lines. Especially 19, its selectivity indexes (SI) between HAF and cancer cell lines was 17.3 times better than the positive control compound podophyllotoxin. The apoptosis, colony formation and transwell migration assays of 7 and 19 were performed on T47D cell line. The in-vivo antitumor effect of 19 was also observed in T47D tumor-bearing mice without obvious toxicity.

Synthesis of novel heterocyclic ring-fused 18ß-glycyrrhetinic acid derivatives with antitumor and antimetastatic activity.

Glycyrrhetinic acid (GA) is one of the most important triterpenoic acids shows many pharmacological effects, especially antitumor activity. GA triggers apoptosis in various tumor cell lines. However, the antitumor activity of GA is weak, thus the synthesis of new synthetic analogs with enhanced potency is needed. By introducing various five-member fused heterocyclic rings at C-2 and C-3 positions, 18 novel GA derivatives were obtained. These compounds were evaluated for their inhibitory activity against the growth of eight different tumor cell lines using a SRB assay. The most active compound 37 showed IC50 between 5.19 and 11.72 µm, which was about 11-fold more potent than the lead compound GA. An apoptotic effect of GA and 37 was determined using flow cytometry and trypan blue exclusion assays. We also demonstrated here for the first time that GA and the synthetic derivatives exhibited inhibitory effect on migration of the tested tumor cells, especially 37 which was about 20-fold more potent than GA on antimetastatic activity.