Oligosaccharides from Gracilaria lemaneiformis better attenuated high fat diet-induced metabolic syndrome by promoting the Bacteroidales proliferation

Polysaccharides from Gracilaria lemaneiformis (GLPs) were shown to reduce high fat diet (HFD)-induced metabolic syndrome (MS), but its high molecular weight (MW) causes lots of barriers to its application in foods as a functional ingredient. In this study, oligosaccharides derived from GLPs (D-GLPs) were prepared, and its effect on HFD-induced MS and inflammation was evaluated in mice. It revealed that D-GLPs reduced fat accumulation, lipid disorders and inflammation in HFD-fed mice accompanied by an improvement of the gut microbiota. D-GLPs reversed HFD-induced gut microbiota dysbiosis characterized by the increased ratio of Bacteroidetes to Firmicutes and the abundance of the Bacteroidales. Spearman correlation analysis showed that some members of the Bacteroidales were positively correlated with reduced fat accumulation, inflammation and lipid disorders. Compared to GLPs, D-GLPs had a better inhibition effect on MS-related parameters, which may be attributed to higher abundance of some Bacteroidales members owing to their prioritization strategy to D-GLPs. The anti-obesity effect was transmissible through fecal transfer from D-GLPs-fed mice to HFD-fed mice, implying that the effect was associated with the gut microbiota. It indicated that D-GLPs can be used as a potential prebiotic agent to MS therapy.