Colchicine-cinnamic acid hybrids with potent anticancer activities: synthesis, in vitro, and in vivo biological...

Cancer represents a critical global health burden, with the clinical application of many chemotherapeutic agents constrained by limited efficacy and significant toxicity. Colchicine, a tubulin-targeting agent, exhibits potent anticancer activity but has a narrow therapeutic window. Conversely, natural cinnamic acid and its derivatives are safe but lack strong antitumor potency and specific targets. To resolve this "potency-toxicity" paradox, a series of colchicine-cinnamic acid hybrids (B1-B12) were designed and synthesized via molecular hybridization, aiming to integrate the strong tubulin-binding activity of colchicine with the biocompatibility of cinnamic acids. Among these derivatives, B3, B6, B7, and B8 showed pronounced cytotoxic activity against B16, 4T1, A549, and HepG2 cancer cell lines. Notably, compound B7 emerged as the most effective, with an IC₅₀ range of 2.5-8.1 nM and excellent selectivity indexes (SI) of 112 against A549 and 55 against HepG2. Further mechanistic studies revealed that B7 effectively disrupted microtubule dynamics in 4T1 cells, induced G2/M-phase cell-cycle arrest, and triggered apoptosis, thereby inhibiting cell proliferation and migration. Molecular docking studies suggested that B7 occupies the colchicine-binding site at the α/β-tubulin interface. In a 4T1 murine breast tumor model, B7 showed significant in vivo antitumor efficacy, achieving a 68.4% tumor growth inhibition (TGI) at 0.6 mg kg^-1day^-1, with a favorable safety profile. These results suggest that colchicine-cinnamic acid hybrids, particularly B7, represent a promising class of lead compounds for developing novel anticancer agents.