Structural Characterization of a Novel Pectin Polysaccharide from Mango (Mangifera indica L.) Peel and Its Regulatory Effects on the Gut Microbiota in High-Fat Diet-Induced Obese Mice

The gut microbiota plays a significant role in metabolic diseases such as obesity. We extracted and purified a new type of pectin polysaccharide (mango peel pectin, MPP) from mango (Mangifera indica L.) peel. The structural analysis results reveal that MPP has a molecular weight (Mw) of 6.76 × 105 Da and the mass fractions of the main components were galacturonic acid (21.36%), glucose (8.85%), and arabinose (5.97%). The results of methylation and NMR analyses reveal that the backbone of MPP consisted of →6)-α-D-GalpAOMe-(1→ and →4)-β-D-Glcp-(1→ linkages. Based on the above structural analysis, we further explored the therapeutic effect of MPP on high-fat diet-induced obese mice. The results demonstrate that MPP significantly suppressed body weight and dyslipidemia, reduced liver damage and lipid accumulation, attenuated changes in adipocyte hypertrophy, and improved glucose homeostasis and insulin resistance, with fasting blood glucose (FBG) levels decreasing by more than 12.8%. Furthermore, the modulatory impact of MPP on gut microbiota composition was investigated. MPP treatment significantly enhanced the levels of short-chain fatty acids (SCFAs) by decreasing the amount of Bacillota and reducing the Bacillota/Bacteroidota ratio, especially with an increase in the total SCFA content of over 64%. Meanwhile, MPP treatment encouraged beneficial bacteria to grow (e.g., Bacteroidota, Akkermansia, and Nanasyncoccus), altered the gut microbiome profiles in mice, and decreased the abundance of harmful bacteria (e.g., Paralachnospira, Coproplasma, Pseudoflavonifractor, Parabacteroides, Acetatifactor, and Phocaeicola). Overall, the findings demonstrate for the first time that MPP treats obesity by alleviating dyslipidemia, improving insulin resistance, and regulating gut microbiota to improve the intestinal environment.