Abstract 287: Design and synthesis of imidazole derivatives as augmented prooxidant anticancer agents (2021)

Abstract Prooxidant augmented therapy is a ROS-based anticancer drug in which a prooxidant compound is linked with an inhibitor of antioxidant enzyme(s). This will lead to an auto-synergistic effect with a consequent intracellular accumulation of ROS. In the current study, 15 new imidazole derivatives (4a-o) were synthesized and assessed as unimolecular auto-augmented prooxidant anticancer agents. The compounds were designed based on incorporating α, β-unsaturated ketones (trans-cinnamaldehyde scaffold) as a thioredoxin reductase enzyme inhibitor, and a prooxidant side chain (R) to the core imidazole scaffold of the recently reported cytotoxic lead compound 2-(5-bromothiophen-2-yl)-4,5-diphenyl-1H-imidazole. The antiproliferative/cytotoxic activity of compounds (4a-o) was assessed against breast adenocarcinoma (MCF-7), hepatocellular carcinoma (HepG2), and colorectal adenocarcinoma (HCT-116) cells using SRB-U assay; IC50's and resistance fractions (R-values) were calculated using Emax mathematical model. HepG2 cells were the most sensitive among other tested tumour cell lines; Compounds 4a, 4c, 4e, 4g, 4i, and 4k showed moderate to high HepG2 cytotoxic/antiproliferative activity with average IC50 of 2.2 µM and the resistant fraction (R-values) did not exceed 30%. In addition, compounds 4a, 4c, 4e, 4g, 4i and 4k significantly increased the total and the intracellular ROS levels within 2 hours of exposure up to 158.2% and 117.7% of normal untreated cells, respectively. The potential apoptotic/necrotic effects of compounds 4a, 4c, 4e, 4g, 4i, and 4k against HepG2 cells were investigated after staining with Annexin V-FITC/PI coupled with flow cytometry. Compound 4e showed the most prominent cell-killing effect by inducing 4 folds apoptosis and 2.5 folds necrosis in HepG2 cells compared to untreated cells. Compounds 4g and 4a showed weaker apoptotic and necrotic effects compared to compound 4e. Furthermore, molecular docking was conducted to assess the interaction between the α, β-unsaturated ketones moiety and x-ray crystal structure of thioredoxin reductase enzyme (pdb: 2J3N) using discovery studio 2.5 Cdocker protocol. Compounds 4a, 4c, 4e and 4 g had a proper 3D arrangement that enables them to fit in FAD-binding the site and perform hydrogen bond with THR 58. In addition, In silico investigation of human intestinal absorption after oral administration for Compounds 4a, 4c, 4e, and 4 g was carried out using Accelrys Discovery studio and revealed possible oral absorption to be confirmed experimentally. In conclusion, the auto-augmented compounds possessing prooxidant ROS generator group and α, β-unsaturated ketones not only elicited tumor cell killing effect via increasing the intracellular ROS level but also showed docking study-based evidence for inhibiting the thioredoxin antioxidant enzyme. Citation Format: Abdel-Sattar M. Omar, Eman M El-labbad, Ahmed M. Al-Abd. Design and synthesis of imidazole derivatives as augmented prooxidant anticancer agents [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 287.