Structural Analysis and Antioxidant and Immunoregulatory Activities of an Exopolysaccharide Isolated from IBifidobacterium longum/I subsp. Ilongum/I XZ01

• Published in: Molecules (Basel, Switzerland) Switzerland), 2023-11, Vol.28 (21)
• Main Authors: Zhang, Xingyuan, Gong, Jing, Huang, Wenyi, Liu, Wen, Ma, Chong, Liang, Rongyao, Chen, Ye, Xie, Zhiyong, Li, Pei, Liao, Qiongfeng
• Format: Article
• Language: English
• Subjects: Antioxidants; Functional foods; Microbial polysaccharides
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules28217448

Bifidobacterium longum subsp. longum XZ01 (BLSL1) is a new strain (isolated from the intestines of healthy people and deposited with the preservation number GDMCC 61618). An exopolysaccharide, S-EPS-1, was successfully isolated from the strain and then systematically investigated for the first time. Some structural features of S-EPS-1 were analyzed by chemical component, HPLC, ultraviolet, infrared, and nuclear magnetic resonance spectrum analyses. These analyses revealed that S-EPS-1 is a neutral heteropolysaccharide with an α-configuration. It contains mainly mannose and glucose, as well as small amounts of rhamnose and galactose. The molecular weight of S-EPS-1 was calculated to be 638 kDa. Several immunoregulatory activity assays indicated that S-EPS-1 could increase proliferation, phagocytosis, and NO production in vitro. In addition, S-EPS-1 could upregulate the expression of cytokines at the mRNA level through TLR4-mediated activation of the NF-κB signaling pathway in RAW 264.7 cells. Finally, S-EPS-1 was demonstrated to exhibit antioxidant activity by ABTS[sup.+•] scavenging, DPPH[sup.•] scavenging, and ferric-ion reducing power assays. Furthermore, S-EPS-1 can protect cells from oxidative stress and shows no cytotoxicity. These beneficial effects can be partly attributed to its antioxidant ability. Thus, the antioxidant S-EPS-1 may be applied as a functional food in the future.