Exploration of Fluorine-Containing Biguanide Analogues with Various Branches: Their Design, Synthesis, and Anti-Proliferative Mechanisms

Objective:: Although the antitumor activity of biguanide compounds in various types of tumors has been demonstrated, there is still a need to enhance their activity through further structural modifications. Methods: In this study, a series of 3-fluoromethoxy-containing biguanide derivatives with different branches was synthesized via intermediate derivatization. Their inhibitory effects on the growth of four bladder cancer cell lines were evaluated to assess the antitumor activities of these compounds. Western blotting experiments were performed to verify the underlying mechanisms. These antitumor effects were also determined in vivo. Results: A total of 10 novel fluorine-containing biguanide compounds with different branches were synthesized and characterized. The results of the MTT and colony formation assays revealed that most of the compounds had excellent antitumor activity, while 5b had the lowest IC50 value. Xenograft in vivo animal studies exhibited that 5b profoundly inhibited tumor growth with no observable toxicities. Both in vitro and in vivo mechanistic studies demonstrated that 5b inhibited tumor growth by down-regulating the p-EGFR signaling pathway. Discussion: Compound 5b, synthesized in this study, is of great significance for enhancing the antitumor activity of biguanides and clarifying its mechanism of action, but its selectivity, indepth verification of the mechanism of action, and comparison with existing drugs still need further study. Conclusion: Most fluorine-containing biguanide compounds with different branches exhibit excellent antitumor activity and low toxicity, with the most effective being 1-1,2-dimethylpropyl-5- (3-Trifluoromethoxyphenyl) biguanide. This finding provides new opportunities to improve the efficacy of biguanides and to develop potential anticancer drugs.