Design and Metal-Free Synthesis and Cytotoxicity Evaluation of 5Hchromeno[ 4,3-b]pyridine Derivatives as Anti-Proliferative Agents

Background: A novel metal-free approach is reported for the synthesis of 5Hchromeno[ 4,3-b]pyridine derivatives. Indeed, chromene derivatives are found to exhibit a broad spectrum of biological activities such as antibacterial, antirhinovirus, antioxidant, cytotoxic, anticancer, and antimicrobial properties. Methods: This method provides easy access to a large number of 5H-chromeno[4,3-b]pyridine scaffolds by the condensation of 3-formylchromene with β-enaminoesters under thermal conditions. All compounds are well characterized by NMR, IR, and mass spectrometry. This is a safe and convenient protocol. Results: Thus, newly synthesized compounds are evaluated for their cytotoxicity against four human cancer cell lines, such as B16 (Skin cancer), DU145 (Prostate cancer), Hela (Cervical cancer), and CHO (Chinese hamster ovary). Conclusion: Among them, compounds 3n and 3o show an excellent anti-proliferation activity against CHO (IC50 12.33+1.13 μM), Hela (IC50 22.33+0.51 μM), and B16 (IC50 27.61+0.8 μM) cell lines, while compounds 3c, 3g, and 3q exhibit promising anti-proliferation against above four human cancer cell lines with IC50 14.96+1.9, 15.59+0.9, 13.8+0.06 μM, respectively, compared with a standard drug Doxorubicin & Mitomycin.