Evaluation of Quercetin, Curcumin, and L-Arginine Against Myeloperoxidase and Nitric Oxide Synthase as Oxidative Stress Biomarkers in Early Childhood Caries - An In Silico Study

Abstract

Background: Oxidative stress plays a significant role in the pathogenesis of Early Childhood Caries (ECC), with salivary peroxidase enzymes and nitric oxide synthase pathways emerging as important biomarkers of disease progression. Natural antioxidants such as curcumin and quercetin have demonstrated potential in modulating oxidative stress responses.

Aim: To evaluate the molecular interactions of curcumin, quercetin, and L-arginine with myeloperoxidase (MPO) and nitric oxide synthase (NOS) using molecular docking analysis.

Materials and Methods: Three ligands, namely curcumin, quercetin, and L-arginine, were docked against human myeloperoxidase (PDB ID: 1CXP) and nitric oxide synthase (UniProt ID: Q27571) using AutoDock Vina implemented in PyRx. Protein preparation and interaction visualization were performed using BIOVIA Discovery Studio Visualizer. Binding affinities and key amino acid interactions were analyzed.

Results: Curcumin exhibited the strongest binding affinity toward NOS (−9.1 kcal/mol), followed by quercetin (−8.9 kcal/mol) and L-arginine (−5.4 kcal/mol). Against MPO, quercetin demonstrated favorable binding (−7.0 kcal/mol) compared with L-arginine (−4.4 kcal/mol). Curcumin and quercetin formed multiple hydrogen-bonding and aromatic interactions within the active sites of both proteins.

Conclusion: Curcumin and quercetin demonstrated stronger interactions with oxidative stress-related targets than L-arginine, highlighting their potential relevance in oxidative stress modulation associated with ECC. Further experimental validation is warranted.