Endotoxemia is mainly caused by a massive burst of inflammatory cytokines as a result of lipopolysaccharide (LPS) invasion. Chitooligosaccharides (COS) is expected to be a potential drug for relieving endotoxemia due to its anti-inflammatory properties. However, the structural parameters of COS are often ambiguous, and the effect of degree of acetylation (DA) of COS on its anti-inflammatory remains unknown. In this study, four COSs with different DAs (0%, 12%, 50% and 85%) and the same oligomers distribution were successfully obtained. Their structures were confirmed by 1H NMR and MS analysis. Then, the effect of DA on the anti-inflammatory activity and relieving endotoxemia potential of COS was researched. The results revealed that COS with a DA of 12% had better anti-inflammatory activity than COSs with other DAs, mainly in inhibiting LPS-induced inflammatory cytokines burst, down-regulating its mRNA expression and reducing phosphorylation of IκBα. Furthermore, this COS showed an obviously protective effect on endotoxemia mice, such as inhibiting the increase in inflammatory cytokines and transaminases, alleviating the injury of liver and intestinal tissue. This study explored the effect of DA on the anti-inflammatory activity of COS for the first time and lays the foundation for the development of COS as an anti-inflammatory drug against endotoxemia.

To find a way to reuse scallop visceral mass and mantle, these aquatic byproducts were used as dietary supplementation and their effects on sea cucumber Apostichopus japonicas culture were investigated, including the growth performance, fatty acid and amino acid compositions, non-specific immune responses and intestinal microflora. The results indicated that the specific growth rate (SGR) of A. japonicas was significantly improved within 20 days by dietary supplementation of scallop visceral mass. Scallop visceral mass supplementation also markedly increased the contents of ω-3 fatty acids including EPA and DHA and ω-3/ω-6 ratio of sea cucumber tissue, which is beneficial to the health of sea cucumber and its commercial value. Furthermore, it is found that supplementation of scallop visceral mass and mantle both enhanced the non-specific immunity and optimized the composition of intestinal microflora of A. japonicas by increasing microbial diversity and promoting the abundance of beneficial taxa. This study reveals the promising prospect of high-value utilization of these scallop “wastes” in sea cucumber culture industry.