Montmorillonite adsorbs uric acid and increases the excretion of uric acid from the intestinal tract in mice

Mangiferin promotes intestinal elimination of uric acid by modulating intestinal transporters

Increasing evidence shows that the intestinal tract plays an important role in maintaining urate homeostasis and might be a potential therapeutic target for hyperuricaemia. However, uric acid-lowering drugs available in the clinic do not target intestinal excretion as a therapeutic strategy. We previously reported that mangiferin had potent hypouricaemic effects in hyperuricaemic animals. However, the underlying mechanisms are not completely clear. Here, we investigated the effects of mangiferin on the intestinal excretion of urate and its underlying mechanisms. The data revealed that mangiferin concentration-dependently promoted the intestinal secretion of endogenous urate in in situ intestinal closed loops in normal and hyperuricaemic mice, as well as inhibited the absorption of exogenous uric acid perfused into the intestinal loops in rats. Administration of mangiferin not only decreased the serum urate levels in the hyperuricaemic mice but also increased the protein expression of ATP-binding cassette transporter, subfamily G, member 2 (ABCG2) and inhibited the protein expression of glucose transporter 9 (GLUT 9) in the intestine. These findings suggested that intestinal ABCG2 and GLUT9 might be pivotal and possible action sites for the observed hypouricaemic effects. Moreover, no significant changes in intestinal xanthine oxidoreductase activities were observed, suggesting that mangiferin did not affect intestinal uric acid generation in the hyperuricaemic mice. Overall, promoting intestinal elimination of urate by upregulating ABCG2 expression and downregulating GLUT9 expression might be an important mechanism underlying mangiferin lowering serum uric acid levels. Mangiferin supplementation might be beneficial for the prevention and treatment of hyperuricaemia.

Effects of bentonite Bgp35b-p on the gut microbiota of mice fed a high-fat diet

BACKGROUND

Bentonite is a natural clay mineral with health-promoting effects due to its high adsorption abilities with high cation-exchange capacity. Previously, we found an anti-obesity effect for Bgp35b-p bentonite produced in South Korea, where its high adsorbent ability of dietary lipids possibly partially removed the lipidic environment in the gut (unpublished). It is hypothesized that Bgp35b-p affects the intestinal microbial community, and thus the microbial changes were investigated via next-generation sequencing targeting the bacterial 16S rRNA gene and bioinformatics using QIIME (Quantitative Insights Into Microbial Ecology) were performed on feces of C57BL/6 male mice fed a high-fat diet (HFD) with the Bgp35b-p.

RESULTS

The HFD caused microbial dysbiosis, characterized by a decrease in the relative abundance of Bacteroidetes and an increase in abundance of Firmicutes and Proteobacteria. It was found that HFD + Bgp35b-p led to significant changes in the microbial compositions of family-level bacteria known as short-chain fatty-acid-producing bacteria. The relative abundance of Ruminococcaceae was significantly increased, and the abundances of Clostridiaceae and Lachnospiraceae were decreased by HFD + Bgp35b-p, shifting close to that in mice fed a normal diet.

CONCLUSION

Bgp35b-p induced compositional changes in intestinal microbiota, which can be considered as a prebiotic effect, thus suggesting that bentonite may be a potential prebiotic functional supplement. © 2018 Society of Chemical Industry.

Intestinal tract is an important organ for lowering serum uric acid in rats

The kidney was recognized as a dominant organ for uric acid excretion. The main aim of the study demonstrated intestinal tract was an even more important organ for serum uric acid (SUA) lowering. Sprague-Dawley rats were treated normally or with antibiotics, uric acid, adenine, or inosine of the same molar dose orally or intraperitoneally for 5 days. Rat’s intestinal tract was equally divided into 20 segments except the cecum. Uric acid in serum and intestinal segment juice was assayed. Total RNA in the initial intestinal tract and at the end ileum was extracted and sequenced. Protein expression of xanthine dehydrogenase (XDH) and urate oxidase (UOX) was tested by Western blot analysis. The effect of oral UOX in lowering SUA was investigated in model rats treated with adenine and an inhibitor of uric oxidase for 5 days. SUA in the normal rats was 20.93±6.98 μg/ml, and total uric acid in the intestinal juice was 308.27±16.37 μg, which is two times more than the total SUA. The uric acid was very low in stomach juice, and attained maximum in the juice of the first segment (duodenum) and then declined all the way till the intestinal end. The level of uric acid in the initial intestinal tissue was very high, where XDH and most of the proteins associated with bicarbonate secretion were up-regulated. In addition, SUA was decreased by oral UOX in model rats. The results suggested that intestinal juice was an important pool for uric acid, and intestinal tract was an important organ for SUA lowering. The uric acid distribution was associated with uric acid synthesis and secretion in the upper intestinal tract, and reclamation in the lower.

Preventive obesity agent montmorillonite adsorbs dietary lipids and enhances lipid excretion from the digestive tract

Western diets are typically high in fat and are associated with long-term complications such as obesity and hepatic steatosis. Because of the enjoyable taste of high-fat diets (HFDs), we are interested in determining how to decrease lipid absorption and enhance lipid excretion from the digestive tract after the consumption of eating fatty foods. Montmorillonite was initially characterized as a gastrointestinal mucosal barrier protective agent for the treatment of diarrhoea. Dietary lipid adsorbent- montmorillonite (DLA-M) was isolated and purified from Xinjiang montmorillonite clay via the water extraction method. Here, we show that DLA-M has an unexpected role in preventing obesity, hyperlipidaemia and hepatic steatosis in HFD-fed rats. Interestingly, combined application of polarized light microscopy and lipid staining analyses, showed that DLA-M crystals have dietary lipid-adsorbing ability in vitro and in vivo, which enhances lipid excretion via bowel movements. In summary, our results indicate that DLA-M prevent HFD-induced obesity. This novel dietary lipid-adsorbing agent can help prevent obesity and its comorbidities.