Molecular Networking-Guided Isolation of a Phenolic Constituent from Prunus mume Seed and Its Antioxidant and Anti-Inflammatory Activities

Prunus mume (Maesil) is used in health foods and alternative medicine in Korea. In the present study, the anti-inflammatory and antioxidant effects of phenolics from P. mume seed extracts were examined. First, the biological activities of various P. mume extracts were evaluated, and the profiles of their chemical compounds were investigated by Global Natural Products Social (GNPS)-molecular networking. Among these extracts, fermented Maesil seed extract (FMSE) showed potent anti-inflammatory and antioxidant activity, and demonstrated the presence of phenolic clusters in GNPS-based studies. Thus, the chemical constituents of this extract were further investigated. Subsequently, the chemical composition of the active CH(2)Cl(2) fraction of FMSE was explored using an advanced GNPS analysis tool, MolNetEnhancer. In addition, the molecular structure of compound 1 from the CH(2)Cl(2) fraction was similarly predicted with Network Annotation Propagation (NAP). Finally, the anti-inflammatory and antioxidant effects of compound 1 were confirmed by lipopolysaccharide (LPS)-induced nitric oxide production and DPPH assay. Western blot analysis revealed that compound 1 downregulated the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins. The molecular docking simulation additionally confirmed significant interactions of 1 with iNOS and COX-2 proteins. Our findings suggested that an integrated GNPS-based approach could prioritize samples in the early fractionation process and improve the accuracy of target compound prediction.