Regulation of <i>Ligustrum robustum</i> (Roxb.) Blume on intestinal flora in C57BL/6 mice fed with western high-sugar and high-fat diet

Long-term consumption of a high-salt and high-fat western diet (WD) is closely associated with the development of metabolic diseases. Literature suggests that <i>Ligustrum robustum</i> (Roxb.) Blume (LR) may regulate intestinal flora to improve adverse reactions and even metabolic diseases caused by WD. Therefore, this study investigated the effects of LR on serum biochemical indexes and intestinal flora structure in mice fed WD. The experimental groups were divided into regular feed group (SD), WD feed group (WD), regular feed+ (18 g/kg) high-dose LR group (SRH), WD feed+(6 g/kg) low-dose LR group (WRL), WD feed + (12 g/kg) medium-dose LR group (WRM) and WD feed + (18 g/kg) high-dose LR group (WRH). Body weight was measured weekly throughout the experiment. After 10 weeks, the serum and colon contents were collected for analysis. The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) in mouse serum were determined using an automatic biochemical analyzer. Additionally, microbial diversity in colon contents was assessed through 16S rDNA amplicon sequencing. There were no significant changes in body weight, serum Glu, ALT, AST, TG, TC, and LDL-C of SRH mice. The abundance of <i>Alloprovettella</i> in the gut microbiota was increased, and the abundance of <i>Lachnospiraceae</i> was decreased. The body weight, Glu, ALT, AST, TG, TC, LDL-C of WD mice were increased significantly. The abundance of <i>Erysipelotrichia</i>, <i>Proteobacteria</i>, and <i>Gammaproteobacteria</i> in the gut microbiota were increased, and the abundance of <i>Rikenellaceae</i>, <i>Alisipes</i>, and <i>Ruminococcaceae</i> were decreased. Compared with WD mice, the body weight and serum AST content in WRL group (WD feed +6 g/kg LR i.g.), WRM group (WD feed +12 g/kg LR i.g.), and WRH group (WD feed+18 g/kg LR i.g.). were significantly decreased, ALT and TG in WRL group were significantly decreased, TC and LDL-C in WRM and WRH groups were significantly increased. The abundance of <i>Ruminococcaceae</i> was increased in WRL group, while the abundance of <i>Bacilli</i> and <i>Lactobacillaceae</i> were decreased. The abundance of <i>Akkermansia</i>, <i>Deltaproteobacteria</i>, <i>Desulfovibrionaceae</i> and <i>Lachnoclostridlum</i> in the intestinal flora of WRH group were increased with decreasing of <i>Erysipelotrichia</i>. In conclusion, drinking low concentrations of LR (less than 6 g/kg) can improve WD-induced intestinal microflora disorder, thus regulating triglycerides and transaminases. However, high concentrations of LR can aggravate WD-induced hypercholesterolemia, which may be related to increased abundance of cholesterol-related flora such as <i>Desulfovibrionaceae</i>. This experiment provides a scientific basis for different dietary groups to drink different concentrations of LR in a healthy way, and provides a new experimental idea for clinical research on the prevention of metabolic diseases caused by poor diet, such as hypercholesterolemia.