Multifunctional pectin derivatives as anticancer agents in colorectal cancer via synthesis, computational insights, and modulation of NRF2/HO-1, HIF-1α, and VEGF/PDGF-D signaling pathways

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, ¹H/¹³C 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 (IC₅₀ = 23.5 μg/mL) and Pectin Hydrazide (IC₅₀ = 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.