Litchi chinensis seed prevents obesity and modulates the gut microbiota and mycobiota compositions in high-fat diet-induced obese zebrafish

Obesity continues to be a global public health challenge. Litchi chinensis seed is rich in bioactive ingredients with pharmacological effects, such as hypoglycemic activity and anti-oxidation. This study aimed to assess the potential anti-obesity effects of L. chinensis seed and the changes of gut microbiota and mycobiota compositions in obese zebrafish induced by a high-fat diet. The anti-obesity effects were supplemented and validated in high-fat diet-induced obese mice. In this study, various chemical components of L. chinensis seed water and ethanol extracts were detected using UHPLC-QE-MS, and both extracts showed strong in vitro antioxidant activities. Network pharmacology analysis showed the potential of the extracts to improve obesity. Litchi chinensis seed powder, water and ethanol extracts decreased the weight of obese zebrafish, improved lipid accumulation and lipid metabolism, regulated appetite, and inhibited cell apoptosis and inflammation of the liver and intestine. They showed similar effects in obese mice, and also reduced the weight of fat tissues, regulated insulin resistance and glucose metabolism, and improved the intestinal barrier. Additionally, L. chinensis seed modulated the compositions of gut microbiota and mycobiota in zebrafish, with the regulation of the proportion of bacteria that produce short-chain fatty acids or affect intestine health, including Cetobacterium, Trichococcus, Aeromonas, Staphylococcus, and Micrococcaceae, and the proportion of fungi that produce mycotoxins or have special metabolic capacities, including Penicillium, Candida, Rhodotorula, and Trichoderma. Spearman's correlation analysis revealed the potential link between zebrafish obesity parameters, gut bacteria and fungi. Overall, these findings indicated that L. chinensis seed effectively improved obesity.