Synthesis and properties of pentabutyryl glucose ester and its effects on the growth, liver and intestinal health, and gut microbiota of zebrafish (Danio rerio)

Butyric acid and its derivatives are widely applied in aquaculture as an alternative to antibiotics, which are beneficial for the growth and health of aquatic animals. However, these products have some disadvantages including poor stability, a bitter taste, and low bioavailability. In this study, a novel butyric acid, namely pentabutyryl glucose ester (PGE), was synthesized, and the effects of PGE on the growth, liver and intestinal health, and gut microbiota of zebrafish were evaluated. We found that the supplementation of PGE at a level of 0.05% promoted the growth performance of zebrafish, decreased the level of serum LPS, ALT, and AST, and improved liver health. The expression levels of pro-inflammatory factors (NF-κB $p65$ and IL-6) were notably downregulated, while those of anti-inflammatory factors (TGF-β and IL-10) were upregulated, in the intestines of zebrafish fed 0.05% PGE compared with the control group. Additionally, inclusion of PGE in the diet of zebrafish increased the relative abundance of probiotic bacteria such as Bacillus and Lentilactobacillus. Overall, this study demonstrated that PGE is beneficial for the growth, liver and intestinal health, and the gut microbiota of zebrafish, providing a novel pathway to improve the application of butyric acid as a feed additive in aquaculture.