Structure–Activity Relationship and Cytotoxic Evaluation of Benzimidazole Derivatives as Potential Antileukemic Agents

Abstract

Benzimidazole derivatives represent a versatile class of heterocyclic compounds with significant potential in anticancer drug discovery. In the present study, a series of benzimidazole analogues was synthesized via the modified Phillips condensation method and structurally characterized using FTIR, ¹H-NMR, ¹³C-NMR, mass spectrometry, and elemental analysis. The synthesized derivatives were evaluated for cytotoxic activity against HL60 (acute promyelocytic leukemia) and K562 (chronic myelogenous leukemia) cell lines using the MTT assay, with IC₅₀ values calculated through nonlinear regression analysis. Several compounds exhibited potent cytotoxic effects in the low micromolar range, with halogen-substituted derivatives such as 2-chloro and 5-bromo analogues showing IC₅₀ values below 6 μM. Selectivity indices confirmed preferential toxicity toward malignant cells compared to normal peripheral blood mononuclear cells. Structure–activity relationship analysis revealed that electronwithdrawing substituents, extended π-conjugation, and para-position halogenation significantly enhanced biological activity, while multiple hydroxyl substitutions reduced potency due to steric hindrance. Comparative evaluation with standard drugs demonstrated that while doxorubicin exhibited higher potency, benzimidazole derivatives offered better selectivity and broader applicability compared to imatinib. Statistical validation using ANOVA and logistic dose–response models confirmed the robustness of experimental findings. These results underscore the potential of benzimidazole derivatives as lead scaffolds for the development of novel antileukemic agents. Future directions include in vivo validation, molecular docking, and ADMET predictions to refine pharmacological profiles and facilitate clinical translation