Novel benzimidazole-triazole hybrids as apoptosis inducing agents in lung cancer: Design, synthesis, 18F-radiolabeling & galectin-1 inhibition studies.

In this study, we have synthesized a new series of benzimidazole-triazole hybrids as galectin-1 (gal-1) mediated apoptosis-inducing agents, and evaluated for their potential anticancer activity against a panel of human cancer cell lines viz. breast cancer (MCF-7 and MDA-MB-231) lung cancer (A-549 and NCI-H460), and human keratinocyte cancer (HaCaT), using MTT assay. The target compound 7c exhibited an excellent growth inhibition against lung cancer (A-549 and NCI-H460) cells with an IC50 value of 0.63 ± 0.21 µM, and 0.99 ± 0.01 µM respectively. The target compound 7c also showed a significant growth inhibition against breast cancer (MCF-7 and MDA-MB-23) with an IC50 value of 1.3 ± 0.18 µM, and 0.94 ± 0.02 µM respectively. In addition, the radiochemical synthesis has been performed using fluorine-18 radionuclide in the GE Tracer-lab FX2N module to prove the target compound 7c as a PET imaging agent. In the final stage, the 18F-7c target compound was successfully purified with 60% ethanol in water. The radiochemical purity was achieved >95% using HPLC, and the residual solvent DMF limit was around 78 ± 3 ppm confirmed by GC analysis. Further, the apoptosis induction by 7c in lung cancer (A-549) cells was confirmed as a result of the decrease in MMP levels, increased percentage of apoptotic cells, and sub G1 phase arrest by JC-1 staining, DAPI staining, annexin V-FITC/PI, and flow cytometric analysis. In addition, the target compound 7c significantly reduced the gal-1 protein levels in a dose-dependent manner as confirmed by ELISA studies. The protein binding studies like Surface Plasmon Resonance (SPR) and Fluorescence Spectroscopy (FS) studies indicated that the target compound 7c is capable of binding to gal-1 with an equilibrium constant (KD) value of 1.19E-06 M, and binding constant (Ka) of 9.5 × 103 M-1 respectively. The in-silico computational studies also revealed possible interactions and pharmacokinetic properties (ADMET) of compound 7c with the binding domain of gal-1. Therefore, the novel benzimidazole-triazole hybrids as apoptosis-inducing agents in lung cancer would be potential cytotoxic and PET imaging agents via gal-1.