Insights into Bioactive Constituents from Pericarp of Garcinia mangostana: Anti-Inflammatory Effects via NF-κB/MAPK Modulation and M1/M2 Macrophage Polarization

Mangosteen (Garcinia mangostana L.) has long been used in traditional Southeast Asian medicine to treat inflammatory-related conditions. In this study, three new compounds, including garcimangone A (1), garcimangone B (2), and the S-form of garcimangone C (3), and 18 known compounds were isolated and investigated for their anti-inflammatory properties and effects on M1- and M2-associated markers. Among the isolated components, γ-mangostin (5), garcinone D (6), morusignin J (15), and fuscaxanthone C (16) showed the most potent NO-inhibitory effects in LPS-stimulated RAW264.7 cells. SAR study revealed that chromeno moiety at C-3,4, oxygen substituents at C-1,3,6,7, and isoprenyl groups at C-2,8 are key structural features that promoted anti-inflammatory activity. Cytokine analysis results indicated that morusignin J (15) and fuscaxanthone C (16) could modulate the production of pro-inflammatory cytokines, such as TNF-α and IL-6, while modulating the anti-inflammatory cytokine IL-10. Western blot results demonstrated that morusignin J (15) modulated the inflammatory response through NF-κB and MAPK signaling and increased the expression of M2-associated markers KLF4 and arginase-1 in LPS-induced RAW264.7 macrophages. Further molecular docking analysis confirmed the high binding affinity of morusignin J (15) with key iNOS residues, such as Gln257, Pro344, Glu371, and Hem901, and the in silico prediction supported its potent oral bioavailability and drug-likeness. These in vitro and in silico findings highlight that pericarps of G. mangostana possess potential as promising natural sources for functional extracts and bioactive constituents for the development of antioxidative and anti-inflammatory candidates, and warrant further in vivo investigation in the future.