Design, synthesis and biological evaluation of novel C-6 and N-9 modified purine nucleosides as EGFR kinase inhibitor

A series of novel purine nucleoside analogs, N-(1-benzylpiperidin-4-yl)-2-chloro-9-alkyl-9H-purin-6-amine derivatives (4a–4j), were synthesized via C-6 amination and N-9 alkylation of 2,6-dichloropurine. The synthetic route utilized simple, metal-free conditions suitable for industrial applications. Structural modifications were introduced to enhance the cytostatic activity of the compounds against breast cancer MCF-7 cell lines. Among the derivatives, compound 4c (N-(1-benzylpiperidin-4-yl)-2-chloro-9-methyl-9H-purin-6-amine) demonstrated significant cytostatic activity with an IC₅₀ of 21.5 μM, outperforming other analogs but remaining less potent than the reference drug, Cisplatin (IC₅₀ = 12.5 μM). Molecular docking studies supported the bio-mimetic nature of these compounds compared to standard drugs. The structure of compound 4c was further validated using DFT through the HOMO and LUMO energy values, which demonstrated well agreement with the experimental spectra. The findings highlight the potential of lower alkyl-modified purine nucleosides as promising leads for further anticancer development and optimization.