Design, Synthesis, Anti-Proliferative Effects, and Mechanistic Details of Fluorine-Containing Biguanide Derivatives with Various Carbon Rings

1a-5a and 1b-4b, the cyclooctyl-containing 3,4-difluorophenyl biguanide analogs, have demonstrated significant potential in developing novel anticancer drugs. The 3,4- difluorophenyl biguanide containing cyclooctyl showed the best antitumor activity among the nine derivatives. This finding offers a novel perspective in developing anticancer drugs and a further improvement in biguanide activity in the future.