Phenolic compounds of Solanum xanthocarpum play an important role in anti-inflammatory effects

Solanum xanthocarpum is used for the treatment of rheumatic arthritis, toothache, sore throats, carbuncle, furuncle, and other inflammatory diseases in traditional Chinese medicine and Ayurvedic medical system, with the phenolic compounds being one of its principal components. In this study, 51 phenolic compounds including seven new compounds 1, 2, 9, 13, 17, 22, and 40 were isolated from the fruits of Solanum xanthocarpum. 40 known compounds 3–8, 10–12, 14–16, 18–21, 23–25, 28–32, 35–39, 41–51 were firstly isolated from Solanum xanthocarpum. Their structures were determined by comprehensive spectroscopic analyses, X-ray crystallography, NMR calculations, chemical methods, and comparisons of spectroscopic data. The results of anti-inflammatory assays indicated that most isolated compounds (3–7, 11–30, 32–37, 39, 40, 42, 43, 45, and 48–51) possessed significant inhibitory activities of the NO release of LPS-induced RAW 264.7 cells, with IC50 values ranging from 10.46 to 47.59 μM. Further analysis by molecular docking implied that most bioactive compounds could interact with the amino acid residues of iNOS proteins, supporting the anti-inflammatory activity of the compounds. Especially, compounds 17–20, 26–27, 32, and 34 showed strong affinities with iNOS proteins. The bioinformatic analysis further revealed the potential anti-inflammatory targets of the phenolic compounds isolated from the fruits of Solanum xanthocarpum.