Abstract:This study focuses on 'Shixia' longan seed polyphenols. The crude polyphenol extract of longan seed was prepared with 60% ethanol，and sequential organic solvent extraction afforded four distinct phases：ethyl acetate，dichloromethane，n-butanol，and aqueous phases. The total phenolic，flavonoid，proanthocyanidin and tannin contents were determined in different extraction phases of longan seeds. An inflammatory model was established in RAW264.7 cells by lipopolysaccharide （LPS） stimulation. The effects of different extraction phases of longan seed polyphenols on nitric oxide （NO） release，reactive oxygen species （ROS） levels，and inflammatory cytokine production in RAW264.7 cells were evaluated. Finally，liquid chromatography-tandem mass spectrometry （LC-MS/MS） was employed to identify the polyphenolic components in the active extract phase. The results indicated that the ethyl acetate fraction contained the following amounts of total phenols，total flavonoids，total proanthocyanidins，and total tannins：（635.56±15.55） mg GAE/g DW，（109.96±2.31） mg RE/g DW，（24.06±1.39） mg EPE/g DW，and （8.22±0.05） mg TAE/g DW. Ethyl acetate fraction polyphenols exhibited concentration-dependent inhibitory effects on nitric oxide （NO） release，reactive oxygen species（ROS） levels，tumor necrosis factor-α （TNF-α），interleukin-6 （IL-6），and prostaglandin E2 （PGE2） in RAW264.7 cells，and its overall anti-inflammatory effect was superior compared with the other fractions. The ethyl acetate fraction contained 20 phenolic compounds，mainly phenolic acids and flavonoids，among which catechin had the highest relative content. In conclusion，ethyl acetate-extracted polyphenols from longan seeds demonstrate potential anti-inflammatory activity.