Ghada H. Elsayed, Asmaa M. Fahim
Abstract This research describes the design, synthesis, characterization, and biological assessment of new Pectin-based Hydrazide and Oxadiazole derivatives as possible anticancer agents. The chemical modification of native Pectin was accomplished using a sequence of esterification, Hydrazide formation, and cyclization with carbon disulfide to yield Pectin Hydrazide (3) and Pectin Oxadiazole (5), confirmed using FT-IR, 1 H/ 13 C NMR, elemental, SEM, and TGA analyses. The in vitro anticancer activity of the synthesized Pectin derivatives was evaluated against HepG2 and Caco2 cancer cells using the neutral red uptake test. Pectin Oxadiazole (IC 50 = 23.5 μg/mL) and Pectin Hydrazide (IC 50 = 39.5 μg/mL) demonstrated the most potent cytotoxic effects against Caco2 cells after 48 h. ELISA assays showed significant reductions in ROS activity and HO-1 protein levels, while qRT-PCR confirmed significant suppression of NRF2, HIF-1α, VEGF, and PDGF-D gene expression in Caco2 cells treated with these Pectin derivatives. Molecular docking and 100-ns molecular dynamics simulations against several cancer-related targets (PDB IDs: 1lc8, 1n3u, 1u6d, 3nl0, 5k5x) demonstrated that Pectin Oxadiazole had a stronger binding affinity with greater structure stability and greater ΔG _bind (− 34 to − 82 kcal/mol) along with a much lower RMSD profile. Additionally, density functional theory (DFT/B3LYP/6-31G) calculations suggested that the presence of N- and S-containing heterocycles resulted in lower HOMO–LUMO gaps and improved dipole moments, thereby increasing electronic reactivity and charge transfer characteristics. Taken together, the Pectin Oxadiazole and Pectin Hydrazide derivatives show combined cytotoxic, antioxidant, and anti-angiogenic activities, thus warranting further investigation toward novel multifunctional agents for the treatment of colorectal cancer.