Gut Microbiota-Derived SCFAs Modulated by Different Structures of Marine Algal Oligosaccharides Alleviate Colitis Through PPARγ Signaling Activation.

Background

Marine algal oligosaccharide (MAO) molecular structural characteristics are closely related to their bioactivity. However, an understanding of the specific relationships between MAO molecular structure (including polymerization degree [DP] and sulfate groups) and bioactivity is lacking.

Methods

In this work, laboratory-prepared DP4 and DP8 MAOs, including agar- (AOs) and κ-, ι-, and λ-carrageenan-oligosaccharides (COs), were examined for their anti-inflammatory activity in RAW264.7 macrophages and therapeutic effect on colitis in mice; additionally, the potential mechanisms involved were explored.

Results

The results showed that CO (ι- and λ-COs) anti-inflammatory activity was higher than that of AOs and was positively correlated with sulfate group content. MAOs with different structures all alleviated colitis symptoms; those with higher sulfate group content and DP showed excellent therapeutic efficacy. MAOs modulated gut microbiota and promoted the enrichment of microbiota-derived short-chain fatty acid production (butyrate), which potentially induced PPARγ signaling and contributed to the impacts of MAOs on mucosal homeostasis restoration.

Conclusions

Therefore, MAOs with higher sulfate content and DP showed improved therapeutic efficacy compared with those with lower contents, which involved higher SCFA production.