Seabuckthorn polysaccharide ameliorates high-fat diet-induced obesity by gut microbiota-SCFAs-liver axis.

Obesity has been reported to be associated with gut microbiome dysbiosis. seabuckthorn fruits have traditionally been used in Tibetan foods and medicines for thousands of years. Seabuckthorn polysaccharide (SP) is one of the main functional components in seabuckthorn fruits. However, the effects of SP on a high-fat diet (HFD)-induced obesity have not yet been elucidated. The purpose of this study is to explore the amelioration effect of SP on obesity induced by HFD and to reveal its mechanism of gut microbiota and its metabolites. Results showed that 12-week SP (0.1%, w/w) dietary supplementation could significantly reduce body weight gain, serum lipid level and liver triglycerides level in obese mice. Notably, the SP treatment elevated p-AMPKα and PPARα proteins expression stimulated the phosphorylation of ACC1 and inhibited the protein expression of FAS, PPARγ, and CD36 in the mice liver. Further, SP also reorganized the gut microbiome by up-regulating the proportion of Muribaculaceae_unclassified, Bifidobacterium, Rikenellaceae_RC9_gut_group, Alistipes, and Bacteroides, and down-regulating the abundance of Lactobacillus, Firmicutes_unclassified, Dubosiella Bilophila, and Streptococcus in HFD-induced obese mice. Moreover, the production of microbial metabolites short-chain fatty acids (SCFAs) in feces has also increased. In addition, correlation analysis results showed that obesity-ameliorating effects of SP were highly associated with levels of SCFAs in feces. Therefore, the regulation of SP on liver lipid metabolism may be due to the variation of the gut microbiome and raised production of SCFAs. These results indicate that SP could play the part of a potential nutraceutical for ameliorating obesity through regulation of the gut-liver axis.

Isorhamnetin attenuates high-fat and high-fructose diet induced cognitive impairments and neuroinflammation by mediating MAPK and NFκB signaling pathways.

Isorhamnetin (ISO), a flavonoid compound isolated from sea-buckthorn (Hippophae rhamnoides L.) fruit, has anti-inflammatory effects. However, the effects of ISO on neuroinflammation and cognitive function are still unclear. The purpose of this study was to evaluate the protective effect of ISO on cognitive impairment in obese mice induced by a high-fat and high fructose diet (HFFD). It has been found that oral administration of ISO (0.03% w/w and 0.06% w/w) for 14 weeks significantly reduced the body weight, food intake, liver weight, liver lipid level, and serum lipid level of HFFD-fed mice. ISO can also significantly prevent HFFD-induced neuronal working, spatial, and long-term memory impairment. Notably, the ISO treatment activated the CREB/BDNF pathway and increased neurotrophic factors in the brains of mice. Furthermore, ISO inhibited HFFD-induced microglial overactivation and down-regulated inflammatory cytokines in both serum and the brain. It can also inhibit the expression of p-JNK, p-p38, and p-NFκB protein in the mouse brain. In conclusion, these results indicated that ISO mitigated HFFD-induced cognitive impairments by inhibiting the MAPK and NFκB signaling pathways, suggesting that ISO might be a plausible nutritional intervention for metabolic syndrome-related cognitive complications.

Development of astaxanthin-loaded layer-by-layer emulsions: physicochemical properties and improvement of LPS-induced neuroinflammation in mice.

Astaxanthin (AST) has been shown to have neuroprotective effects; however, its bioavailability in vivo is low due to its hydrophobic properties. In this study, lactoferrin (LF) was prepared by heat-treatment at different temperatures, and on this basis, a layer-by-layer self-assembly method was used to construct double-layer emulsions with LF as the inner layer and polysaccharide (beet pectin, BP or carboxymethyl chitosan, CMCS) as the outer layer. Then AST was encapsulated in the emulsions and their physiochemical properties and function were investigated. The results indicated that high temperature heated LF (95 °C) showed a more stable structure than the lower temperature one, and the exposed internal nonpolar groups of LF could give the emulsion an enhanced stability. The rheology results showed that compared with CMCS, the double-layer emulsion formed by BP had a higher viscosity. In addition, the 95 °C LF-AST-BP emulsion showed the best stability among all the bilayer emulsions. The best emulsion was then used as a model drug to investigate its effects on lipopolysaccharide (LPS)-induced neuroinflammation and learning-memory loss in C57BL/6J mice. Through animal behavioral experiments, it was found that dietary supplementation with the AST emulsion could effectively improve the brain cognitive and learning memory impairment caused by inflammation. Transmission electron microscopy, mRNA and western blotting results also illustrated that the AST emulsion could alleviate neuroinflammation caused by LPS. This study provides a feasible scheme for exploring an AST loaded system and may be suitable for food and drug applications.