Xanthones from Garcinia pedunculata and Garcinia nujiangensis and their anti-inflammatory activity

Abstract

Ten novel xanthones, garpedunxanthones A−G (1−5, 6a/6b, 7a/7b) and nujiangxanthone Q (8), along with sixteen known analogs (9−24), were isolated from Garcinia pedunculata and G. nujiangensis. Their structures were elucidated through high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) data, comprehensive nuclear magnetic resonance (NMR) spectroscopic analyses, and electronic circular dichroism (ECD) calculations. All compounds without cytotoxicity were assessed for anti-inflammatory properties by measuring the inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 cells. Structure-activity relationships are also discussed. Compounds 7b, 19, and 21 exhibited significant anti-inflammatory activity with IC₅₀ values of 16.44 ± 0.69, 14.28 ± 0.78, and 10.67 ± 3.28 μmol·L⁻¹, respectively. Enzyme-linked immunosorbent assay (ELISA) demonstrated that compounds 7b, 19, and 21 inhibited the expression of pro-inflammatory cytokines TNF-α and IL-6 in a dose-dependent manner. The inhibitory effect of compound 21 on IL-6 at 20 μmol·L⁻¹ was comparable to that of the positive control. In network pharmacology studies, potential targets of compounds and inflammation were identified from PharmMapper and GeneCards databases. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the overlapped targets were intricately associated with major pathogenic processes linked to inflammation, including positive regulation of mitogen-activated protein kinase (MAPK) cascade, protein kinase activity, NO synthase regulator activity, MAPK signaling pathway, and EGFR tyrosine kinase inhibitor resistance.