Black garlic melanoidins prevent obesity, reduce serum LPS level and modulate the gut microbiota composition in high-fat diet induced obese C57BL/6J mice
The objective of this study was to assess the potential anti-obesity effects of black garlic melanoidins (MLDs) and gut microbiota changes in an animal model, hypothesizing that oral administration of MLDs can be partially mediated by modulating intestinal microbiota via inhibiting the formation of lipopolysaccharides (LPS) and promoting the production of short chain fatty acids (SCFAs). The effects of MLDs on high-fat diet (HFD) induced obese C57BL/6J mice were investigated for 12 weeks with low (50 mg/kg/day), medium (100 mg/kg/day) and high (200 mg/kg/day) doses. Results showed that oral administrations of MLDs markedly reduced a high fat diet-induced gain in weight and white adipose tissues weights and reversed glucose tolerance, especially the high dose of MLDs. Besides, MLDs could alleviate the dyslipidaemia, significantly suppress hepatic lipid accumulation and steatosis and effectively ameliorate lipid metabolism. This was accompanied by a significant reduction in plasma LPS and a significant increase in production of SCFAs. The MLDs could down-regulate the expression of fatty acid synthase (FAS) and interleukin-6 (IL-6), up-regulate adipose triacylglyceride lipase (ATGL) and hormone sensitive lipase (HSL) in adipose tissues and livers at mRNA levels. Moreover, after the oral administration of MLDs, the intestinal microbial environment improved in the sense that bacterial diversity and richness increased. Intervention with MLDs modified the gut microbiota in HFD-induced mice, increasing the number of SCFA-producing bacteria (Bacteroidaceae) and reducing opportunistic pathogens (Enterobacteriaceae, Desulfovibrionaceae). An increased abundance of other probiotics including Lactobacillaceae and Akkermansiaceae was also observed. In conclusion, MLDs could improve the glucose tolerance, induce the production of SCFAs and inhibit the production of endotoxin LPS, most likely mediated by modulating gut microbiota. Therefore, it seems MLDs exhibit anti-obesity effect and might be used as a potential agent against obesity.