Steaming and Sodium Bicarbonate-Assisted Aqueous Extraction of Panax notoginseng Stems and Leaves: Evaluation of Xanthine Oxidase Inhibitory Potential

Panax notoginseng stems and leaves are abundant agricultural residues generated during root harvest, rich in flavonoids yet remain largely underutilized as a valuable phytochemical source. This study optimized a green steaming-sodium bicarbonate aqueous extraction process via orthogonal design. Optimal conditions (steaming 1 h, 1.0% food-grade NaHCO3, boiling extraction 2 h, 1:20 g/mL) achieved a solid yield of 13.50 ± 0.41%, significantly higher than conventional water extraction (7.98 ± 0.41%, p < 0.05), demonstrating enhanced recovery of bioactive compounds. The extract exhibited 91.95 ± 0.08% xanthine oxidase inhibition (IC50 = 5.0 mg/mL) with reversible mixed-type inhibition (Ki = 4.99 mg/mL). UHPLC-MS/MS identified 3392 metabolites, predominantly flavonoids, alkaloids, and organic acids with potential XO inhibitory activity. Network pharmacology and molecular docking revealed multi-target interactions involving ADRA2A, ADA, GAA, PNP, and PTGS2 enriched in purine metabolism and AGE-RAGE signaling pathways, with quercetin 3-Gentiobioside exhibiting the strongest binding affinity and favorable ligand-target interactions (ΔG = −12.91 kcal/mol). This eco-friendly strategy employs only pure water and food-grade additives, efficiently concentrating xanthine oxidase inhibitors and offering a clean-label, sustainable approach for high-value utilization of P. notoginseng agricultural residues. These findings provide a pharmacological basis for developing functional foods targeting hyperuricemia and associated metabolic disorders.