Bovine α-lactalbumin-derived peptides attenuate TNF-α-induced insulin resistance and inflammation in 3T3-L1 adipocytes through inhibiting JNK and NF-κB signaling

Recent progress in the preparation of bioactive peptides using simulated gastrointestinal digestion processes

Bioactive peptides (BAPs) represent a unique class of peptides known for their extensive physiological functions and their role in enhancing human health. In recent decades, owing to their notable biological attributes such as antioxidant, antihypertensive, antidiabetic, and anti-inflammatory activities, BAPs have received considerable attention. Simulated gastrointestinal digestion (SGD) is a technique designed to mimic physiological conditions by adjusting factors such as digestive enzymes and their concentrations, pH levels, digestion duration, and salt content. Initially established for analyzing the gastrointestinal processing of foods or their constituents, SGD has recently become a preferred method for generating BAPs. The BAPs produced via SGD often exhibit superior biological activity and stability compared with those of BAPs prepared via other methods. This review offers a comprehensive examination of the recent advancements in BAP production from foods via SGD, addressing the challenges of the method and outlining prospective directions for further investigation.

Modulation of Acute Intestinal Inflammation by Dandelion Polysaccharides: An In-Depth Analysis of Antioxidative, Anti-Inflammatory Effects and Gut Microbiota Regulation

Acute colitis is a complex disease that can lead to dysregulation of the gut flora, inducing more complex parenteral diseases. Dandelion polysaccharides (DPSs) may have potential preventive and therapeutic effects on enteritis. In this study, LPS was used to induce enteritis and VC was used as a positive drug control to explore the preventive and therapeutic effects of DPS on enteritis. The results showed that DPS could repair the intestinal barrier, down-regulate the expression of TNF-α, IL-6, IL-1β, and other pro-inflammatory factors, up-regulate the expression of IL-22 anti-inflammatory factor, improve the antioxidant capacity of the body, and improve the structure of intestinal flora. It is proved that DPS can effectively prevent and treat LPS-induced acute enteritis and play a positive role in promoting intestinal health.

The preventive effect of Glycyrrhiza polysaccharide on lipopolysaccharide-induced acute colitis in mice by modulating gut microbial communities

Acute colitis is characterised by an unpredictable onset and causes intestinal flora imbalance together with microbial migration, which leads to complex parenteral diseases. Dexamethasone, a classic drug, has side effects, so it is necessary to use natural products without side effects to prevent enteritis. Glycyrrhiza polysaccharide (GPS) is an α-d-pyranoid polysaccharide with anti-inflammatory effects; however, its anti-inflammatory mechanism in the colon remains unknown. This study investigated whether GPS reduces the lipopolysaccharide (LPS)-induced inflammatory response in acute colitis. The results revealed that GPS attenuated the upregulation of tumour necrosis factor-α, interleukin (IL)-1β, and IL-6 in the serum and colon tissues and significantly reduced the malondialdehyde content in colon tissues. In addition, the 400 mg/kg GPS group showed higher relative expressions of occludin, claudin-1, and zona occludens-1 in colon tissues and lower concentrations of diamine oxidase, D-lactate, and endotoxin in the serum than the LPS group did, indicating that GPS improved the physical and chemical barrier functions of colon tissues. GPS increased the abundance of beneficial bacteria, such as Lactobacillus, Bacteroides, and Akkermansia, whereas pathogenic bacteria, such as Oscillospira and Ruminococcus were inhibited. Our findings indicate that GPS can effectively prevent LPS-induced acute colitis and exert beneficial effects on the intestinal health.

Production of Food-Derived Bioactive Peptides with Potential Application in the Management of Diabetes and Obesity: A Review

The prevalence of diabetes mellitus and obesity is increasing worldwide. Bioactive peptides are naturally present in foods or in food-derived proteins. Recent research has shown that these bioactive peptides have an array of possible health benefits in the management of diabetes and obesity. First, this review will summarize the top-down and bottom-up production methods of the bioactive peptides from different protein sources. Second, the digestibility, bioavailability, and metabolic fate of the bioactive peptides are discussed. Last, the present review will discuss and explore the mechanisms by which these bioactive peptides help against obesity and diabetes based on in vitro and in vivo studies. Although several clinical studies have demonstrated that bioactive peptides are beneficial in alleviating diabetes and obesity, more double-blind randomized controlled trials are needed in the future. This review has provided novel insights into the potential of food-derived bioactive peptides as functional foods or nutraceuticals to manage obesity and diabetes.

Anti-Hyperuricemic, Nephroprotective, and Gut Microbiota Regulative Effects of Separated Hydrolysate of α-Lactalbumin on Potassium Oxonate- and Hypoxanthine-Induced Hyperuricemic Mice

SCOPE

This study aims to investigate the anti-hyperuricemic and nephroprotective effects and the potential mechanisms of the separated gastrointestinal hydrolysates of α-lactalbumin on hyperuricemic mice.

METHODS AND RESULTS

The gastrointestinal hydrolysate of α-lactalbumin, the hydrolysate fraction with molecular weight (MW) < 3 kDa (LH-3k), and the fragments with smallest MW among LH-3K harvested through dextran gel chromatography (F5) are used. Hyperuricemia mice are induced via daily oral gavage of potassium oxonate and hypoxanthine. F5 displays the highest in vitro xanthine oxidase (XO) inhibition among all the fractions separated from LH-3k. Oral administration of F5 significantly reduces the levels of serum uric acid (UA), creatinine, and urea nitrogen. F5 treatment could ameliorate kidney injury through alleviating oxidative stress and inflammation. F5 alleviates hyperuricemia in mice by inhibiting hepatic XO activity and regulating the expression of renal urate transporters. Gut microbiota analysis illustrates that F5 administration increases the abundance of some SCFAs producers, and inhibits the growth of hyperuricemia and inflammation associated genera. LH-3k exhibits similar effects but does not show significance as those of the F5 fraction.

CONCLUSION

The anti-hyperuricemia and nephroprotective functions of F5 are mediated by inhibiting hepatic XO activity, ameliorating oxidative stress and inflammation, regulating renal urate transporters, and modulating the gut microbiota in hyperuricemic mice.

Astragaloside IV Regulates Insulin Resistance and Inflammatory Response of Adipocytes via Modulating CTRP3 and PI3K/AKT Signaling

INTRODUCTION

Emerging evidence showed that adipocytes are important regulators in controlling insulin resistance in type 2 diabetes mellitus (T2DM). So far, compounds isolated from natural plants have been widely studied for their roles in alleviating T2DM-associated complications. This work evaluated the actions of astragaloside IV (AS-IV) on insulin resistance and inflammatory biomarker expression in adipocytes and explored the potential mechanisms.

METHODS

Glucose consumption of the adipocytes was determined by a glucose assay kit; the mRNA expression levels of glucose transporter type 4 (GLUT-4), interleukin-6 (IL-6), TNF-α and C1q tumor necrosis factor-related protein 3 (CTRP3) were measured by quantitative real-time PCR (qRT-PCR); the protein levels were determined by western blot assay and enzyme-linked immunosorbent assay.

RESULTS

AS-IV concentration-dependently increased glucose consumption in the insulin resistance adipocytes. Further qRT-PCR results showed that AS-IV concentration-dependently reduced adipocyte IL-6 and TNF-α expression. Moreover, GLUT-4 expression in adipocytes was also significantly upregulated by AS-IV. Furthermore, we found that AS-IV concentration-dependently increased CTRP3 expression in adipocytes. CTRP3 silence decreased glucose consumption, upregulated IL-6 and TNF-α expression and downregulated GLUT-4 mRNA expression in 200 µM AS-IV-treated adipocytes. Moreover, AS-IV treatment enhanced the activity of phosphoinositide 3-kinase (PI3K)/AKT signaling in adipocytes, which was markedly attenuated by CTRP3 silencing. Importantly, inhibition of PI3K/AKT signaling also attenuated AS-IV induced an increase in glucose consumption and GLUT-4 expression and a decrease in IL-6 and TNF-α expression of adipocytes.

CONCLUSIONS

Collectively, our data indicated that AS-IV attenuated insulin resistance and inflammation in adipocytes via targeting CTRP3/PI3K/Akt signaling.