Characteristics of Water-soluble Pectin from Greengage and Its Anti-inflammatory Activity in LPS-induced RAW246.7 Cells

In this study, the water soluble pectin (WSP) from greengage juice was extracted. The structure and composition of WSP were characterized by high performance liquid chromatography (HPLC), high performance gel filtration chromatography (HPGFC), Fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM) and X-ray diffraction (XRD). And the anti-inflammatory activity of WSP in lipopolysaccharide (LPS)-induced RAW246.7 cells was evaluated by enzyme-linked immunosorbent assay (ELISA). The results showed that WSP was a low-methoxy pectin with DE value of 18.89%. The content of galacturonic acid (GalA) was 69.72%, and the galactose (Gal) was the predominant neutral sugar with the content of 18.36%. The molecular weight (Mw) of WSP was 353.73 kDa. WSP significantly inhibited the release of tumor necrosis factor α (TNF-α) (P<0.05), interferon-γ (IFN-γ) (P<0.05), interleukin-6 (IL-6) (P<0.001) and increasing the secretion of interleukin-10 (IL-10) (P<0.01). The effects of WSP on Janus kinase/signal transduction and transcription activator signaling pathway (JAK/STAT signaling pathway) were investigated by real-time quantitative PCR and Western blot in order to clarify the anti-inflammatory mechanism. Compared with LPS group, WSP significantly upregulated the mRNA expressions of JAK1 (P<0.01), JAK2 (P<0.05), JAK3 (P<0.001), STAT1 (P<0.001), STAT2 (P<0.001) and STAT3 (P<0.05). Further analysis showed that the phosphorylation levels of JAK1 and STAT3 were significantly inhibited by WSP treatment (P<0.05). Therefore, the WSP can alleviate LPS-induced inflammation in RAW264.7 cells by interfering with JAK/STAT signaling pathway and inhibiting the phosphorylation levels of JAK and STAT families related to inflammatory signaling. This study can provide a basis for the evaluation of the health improvement effect of greengage fruit and the development of value added greengage product.