Efficient Synthesis with Green Chemistry Approach of Novel Pharmacophores of Imidazole-Based Hybrids for Tumor Treatment: Mechanistic Insights from In Situ to In Silico

SIMPLE SUMMARY: Here, we report the eco-friendly synthesis and antitumor potential of the imidazole hybrids of pyrimidine. The results showed that all the compounds possess excellent inhibition of tumors, promoting enzymes hCA-IX and hCA-II. Furthermore, the selectivity index showed that compounds 7, 10, and 11 are selective inhibitors of hCA-IX, while compound 2 is a selective inhibitor of hCA-IX. More importantly, all the active inhibitors are toxic to the breast cancer cell line and non-cytotoxic for the normal breast cell line. These compounds would be a suitable choice to investigate in the in vivo models to check their efficacy against these particular targets. These newly identified human carbonic anhydrase inhibitors have potential to be considered as therapeutic leads for the treatment of CA-related diseases, especially for breast and lung tumors and glaucoma. Furthermore, lead optimization and preclinical and clinical investigations of these compounds are necessary to develop potential drug entities for the treatment of cancer. ABSTRACT: Imidazole-based pyrimidine hybrids are considered a remarkable class of compounds in pharmaceutical chemistry. Here, we report the anticancer bioactivities of eleven imidazole-based pyrimidine hybrids (1–11) that specifically target cytosolic carbonic anhydrase (CAs) isoenzymes, including human CA-II and human CA-IX (hCA-II, and hCA-IX). A highly eco-friendly aqueous approach was used for the formation of a carbon–carbon bond by reacting aromatic nitro group substitution of nitroimidazoles with carbon nucleophiles. The in vitro results indicate that this new class of compounds (1–11) includes significant inhibitors of hCA IX with IC(50) values in the range of 9.6 ± 0.2–32.2 ± 1.0 µM, while hCA II showed IC(50) values in range of 11.6 ± 0.2–31.1 ± 1.3 µM. Compound 2 (IC(50) = 12.3 ± 0.1 µM) showed selective inhibition for hCA-II while 7, 8, and 10 (IC(50) = 9.6–32.2 µM) were selective for hCA-IX. The mechanism of action was investigated through in vitro kinetics studies that revealed that compounds 7, 3, 11, 10, 4, and 9 for CA-IX and 1, 2, and 11 for CA-II are competitive inhibitors with dissociation constant (Ki) in the range of 7.32–17.02 µM. Furthermore, the in situ cytotoxicity of these compounds was investigated in the human breast cancer cell line MDA-MB-231 and compared with the normal human breast cell line, MCF-10A. Compound 5 showed excellent anticancer/cytotoxic activity in MDA-MB-231 with no toxicity to the normal breast cells. In addition, in silico molecular docking was employed to predict the binding mechanism of active compounds with their targets. This in silico observation aligned with our experimental results. Our findings signify that imidazole-based hybrids could be a useful choice to design anticancer agents for breast and lung tumors, or antiglaucoma compounds, by specific inhibition of carbonic anhydrases.