Ultrasonic extraction, Structural Characterization, and Immunoactivity of Polysaccharides From Syzygium jambos (L.) Alston

ABSTRACT This research emphasized the extraction and separation of polysaccharides derived from Syzygium jambos (L.) Alston (PSJAP‐5), as well as analyses of their structural characteristics and immunomodulatory activities. This study initially employed response surface methodology to determine the extraction conditions of polysaccharides. The average molecular weight of PSJAP‐5 was 58 102 Da, and its monosaccharide composition was galactose, arabinose, galacturonic acid, glucuronic acid, and rhamnose (39.84:29.13:21.97:6.02:4.17). In vitro studies showed that PSJAP‐5 promoted the proliferation and phagocytosis of macrophages. Meanwhile, PSJAP‐5 (25–200 µg/mL) promoted the release of NO and ROS, and increased the levels of IL‐6, TNF‐α, and IL‐1β. After pretreating macrophages with TLR4, NF‐κB, and MAPK inhibitors, the immunoenhancing effects of PSJAP‐5 on macrophages treated with the inhibitors were decreased. Similarly, PSJAP‐5 promoted the phosphorylation of p38 in the MAPK signaling pathway and reduced the phosphorylation of IκBα in the NF‐κB signaling pathway in RAW264.7 cells. PSJAP‐5 might serve as a potential immunomodulator for the treatment of diseases characterized by impaired immune function.