Metallothionein–Kidney Bean Polyphenol Complexes Showed Antidiabetic Activity in Type 2 Diabetic Rats by Improving Insulin Resistance and Regulating Gut Microbiota

Abstract

Previous studies have shown that interaction between polyphenols and proteins can benefit health, but the mechanism of its antidiabetic effect has not been thoroughly elucidated. Therefore, this study aimed to investigate the impact of the metallothionein (MT)–kidney bean polyphenol complex on the blood glucose levels and gut microbiota of rats with type 2 diabetes mellitus (T2DM) induced by a high-fat diet combined with streptozotocin (STZ). After 7 weeks of intervention, the MT–kidney bean polyphenol complex can significantly improve the loss of body weight, the increase in blood glucose and blood lipids, and insulin resistance caused by T2DM in rats. In addition, it can effectively alleviate the damage to the pancreas and liver in rats. The MT–kidney bean polyphenol complex also significantly increased the concentrations of six short-chain fatty acids (SCFAs) in the intestinal contents of rats, especially acetic acid, propionic acid, and butyric acid (296.03%, 223.86%, and 148.97%, respectively). More importantly, the MT–kidney bean polyphenol complex can significantly reverse intestinal microflora dysbiosis in rats caused by T2DM, increase intestinal microorganism diversity, improve the abundance of various beneficial bacteria, and reshape the gut microbiota. In summary, the hypoglycemic effect of the MT–kidney bean polyphenol complex and its possible mechanism was expounded in terms of blood glucose level, blood lipid level, and gut microbiota, providing a new perspective on the development of the MT–kidney bean polyphenol complex as functional hypoglycemic food.

Anti-Obesity Effect of Combining White Kidney Bean Extract, Propolis Ethanolic Extract and CrPi3 on Sprague-Dawley Rats Fed a High-Fat Diet

“…Carbohydrates and partially and nondigestible polysaccharides are fermented by the gut microbiota, into a significant number of fatty acid molecules called saturated fatty acids (SCFAs) which are good for gut health [ 104 ]. There is a strong correlation between a lower colonic pH and an elevated intestinal SCFA concentration.…”

“…There is a strong correlation between a lower colonic pH and an elevated intestinal SCFA concentration. Butyric, propionic, and acetic acids are the three main SCFAs that comprise the SCFA profile: acetic acid accounts for more than 95% of the total [ 104 ]. According to certain reports, the metabolism of fat and glucose involves the involvement of all three acids.…”

“…According to certain reports, the metabolism of fat and glucose involves the involvement of all three acids. Acetic and propionic acids help regulate body weight and insulin sensitivity [ 104 ]. Butyric acid not only keeps colon cancer away, but it also keeps the environment inside the intestines stable.…”

“…The most notable improvements were seen in supplement III in the colonic pH, SCFA profile, and SCFA concentration (propionic acid and acetic acid were the predominant SCFAs, with isobutyric and butyric acid accounting for smaller proportions). This outcome can be explained by the extract from white kidney beans’ high polyphenol content, which improved the gut microbiota’s composition and encouraged the rat colon’s production of SCFAs while reducing inflammation [ 104 ].…”