<I>In silico</I> Molecular Docking Analysis of Procyanidin and Quercetin as Regulators of Inflammation in Allergic Rhinitis

Allergic rhinitis (AR) is an inflammatory disorder of the nasal mucosa caused by immune hypersensitivity to airborne allergens. AR pathophysiology involves pro-inflammatory mediators-, such as tumor necrosis factor alpha (TNF-α), nuclear factor-kappa B (NF-κB), interleukin-6 (IL-6), interleukin-8 (IL-8), and malondialdehyde (MDA). Modulating these mediators is a potential therapeutic strategy. This study evaluated the anti-inflammatory potential of apple polyphenols, specifically procyanidin and quercetin, using in silico molecular docking against key inflammatory proteins related to AR. High-resolution three-dimensional structures of TNF-α, NF-κB, IL-6, IL-8, and MDA were obtained from the Protein Data Bank, and ligand structures were prepared and optimized in AutoDock. Docking validation was performed by redocking native ligands, and the best poses were assessed for binding affinity and interaction profiles. Procyanidin and quercetin exhibited moderate to strong binding affinities toward all targets, with binding energies ranging from −1.34 to −7.63 kcal/mol, and inhibition constants suggesting potential biological relevance. Both ligands formed stable hydrogen bonds and hydrophobic interactions with residues involved in cytokine activity and transcriptional regulation. Quercetin displayed higher affinity for TNF-α and NF-κB, whereas procyanidin showed strong interactions with MDA, suggesting additional antioxidant effects. These findings suggest that procyanidin and quercetin from apple extract may modulate multiple inflammatory and oxidative pathways in AR, warranting further biological evaluation as potential therapeutic agents.