Physicochemical characterization of a polysaccharide from green microalga Chlorella pyrenoidosa and its hypolipidemic activity via gut microbiota regulation in rats

A bioactive polysaccharide from microalga Chlorella pyrenoidosa (CPP) was successively prepared via DEAE-52 and G-100 columns. NMR analysis showed that the main glycosidic bonds were composed of 1,2-linked-α-L-Fucp, 1,4-linked-α-L-Rhap, 1,4-linked-β-L-Araf, 1-linked-α-D-Glcp, 1,3-linked-β-D-GlcpA, 1,4-linked-β-D-Xylp, and 1,3,6-linked-β-D-Manp. Its molecular weight was 5.63×106 Da. The hypolipidemic effect and intestinal flora regulation of CPP on diet-induced rats were evaluated through histopathology and biochemistry analysis. CPP could improve plasma and liver lipid metabolism and accelerate the metabolism of the cecal total bile acids and SCFAs. CPP has also up-regulated the AMPK-a and down-regulated the ACC, SREBP-1c, and HMG-CoA expressions. Moreover, with the 16S rRNA gene sequencing, it was revealed that the composition of intestinal flora changed drastically after treatment, such as the bloom of Coprococcus_1, Lactobacillus, and Turicibacter, whereas a strong reduction of [Ruminococcus]_gauvreaui...