Epigallocatechin gallate prevents and alleviates type 2 diabetes mellitus (T2DM) through gut microbiota and multi-organ interactions in Wistar healthy rats and GK T2DM rats

INTRODUCTION

As the main active ingredient of the first FDA-approved phytochemical drug, epigallocatechin gallate (EGCG) can effectively alleviate glucolipid metabolic disorders. However, existing studies mainly focuses on the treatment of EGCG in disease models, with limited focus on its preventive effect on diseases in healthy models.

OBJECTIVES

This study investigated how EGCG prevents and alleviates T2DM through gut microbiota and multi-organ interactions in Wistar healthy rats and GK T2DM rats.

METHODS

The GK T2DM rat strain was established through repeated selective breeding of Wistar rats with glucose intolerance. Whether and how EGCG prevents and alleviates T2DM were evaluated, including glucose production and absorption efficiency, glucose transport, glucose metabolism, glucose excretion, T2DM-related tissue damage, gut microbiota, and liver transcriptome.

RESULTS

The health benefits of EGCG are primarily reliant on the involvement of the gut microbiota. Our study showed that although the specific microbial communities involved differ, the bidirectional interaction between EGCG and gut microbiota is widespread in healthy rats and T2DM rats. EGCG intervention elevated the relative abundance of specific microbial communities, which in turn promoted the metabolic processing of EGCG in the gut, producing numerous EGCG metabolites that may contribute to preventing and alleviating T2DM. In healthy rats, EGCG intervention selectively enhanced insulin secretion and serum insulin levels to prevent T2DM. In T2DM rats, EGCG intervention selectively lowered blood glucose levels, improved insulin resistance, delayed glucose production and absorption, and promoted urinary glucose excretion to alleviate T2DM. In both healthy and T2DM rats, EGCG intervention universally reduced gut microbiota-derived lipopolysaccharides, maintained systemic oxidative stress homeostasis, alleviated liver and kidney damage, increased muscle glycogen content, and promoted beige thermogenesis in white fat, thus demonstrating potential for preventing and alleviating T2DM.

CONCLUSION

As a natural active ingredient, EGCG could prevent and alleviate T2DM through gut microbiota and multi-organ interactions.

Synergistic action of a Momordica charantia-abundant peptide with insulin regulates blood glucose metabolism in db/db mice via a novel second-hit mechanism on insulin receptor activation

Diabetes is a global health challenge, often managed with insulin therapy. However, the direct interactions of insulin receptor (IR)-binding macromolecules with IR remain poorly understood. In this study, we explored the hypoglycemic mechanisms of BG68, a 68-amino-acid polypeptide abundant in Momordica charantia, and its stable, gastro-resistant 9-amino-acid peptide (mcIRBP-9) in combination with insulin in a type 2 diabetes mouse model. We characterized the binding kinetics of BG68 and mcIRBP-9 to the IR/insulin complex using isothermal titration calorimetry (ITC) and hydrogen‑deuterium exchange mass spectrometry (HDX-MS). Functional assays, including Western blot and phosphoproteome analyses, were performed to assess IR phosphorylation. Our findings revealed that BG68 and mcIRBP-9 synergistically enhanced glucose clearance with insulin. HDX-MS analysis showed that mcIRBP-9 bound to IR at sites distinct from insulin, initially engaging the L1 and α-CT regions before extending to L2, FnIII-2, and FnIII-3 domains. ITC confirmed spontaneous binding to the IR/insulin complex with moderate affinity, while phosphoproteome analysis demonstrated that mcIRBP-9 significantly enhanced IR phosphorylation at Y1356 and Y1362, thereby amplifying IR kinase activity and promoting glucose clearance. In conclusion, our findings suggested that mcIRBP-9 provided a "second hit" to IR following insulin binding, further enhancing IR activation. This novel mechanism highlighted mcIRBP-9 as a promising candidate for improving the efficacy of insulin therapy and combating insulin resistance in type 2 diabetes.

RNA-seq reveals Lysyl oxidase as a potential biomarker of glomerular function in diabetic nephropathy in rats

PURPOSE

We downloaded the gene expression profiles of patients with diabetic nephropathyfrom the GEO database and combined it with differential gene analysis of rat transcriptome,our study employed animal models to examine the role of key hub genes in diabetic nephropathy and to pinpoint significant gene regulation in this disease.

METHODS

An examination of differential expression was performed using the online analysis tool GEO2R and the DN-related datasets GSE30528 and GSE1009 obtained from the GEO database. A comparison of gene expression between the normal and diabetic nephropathy groups was conducted using the RNA-seq technique. We further examined body weightchanges and detected the levels of blood glucose, 24-hour urine microalbumin, and expression ofIL-6 and TNF-α.We also measured the levels of Lysyl oxidase (LOX) using quantitative real-time PCR and western blotting.

RESULTS

We found that LOX was among the top 10 significantly differentially expressed genes in both the GEO database and transcriptome. Moreover, the levels of fasting blood glucose,24-h urine microalbumin, and expression of TNF-α and IL-6 were significantlyincreasedin the DNthanin the normal group (P < 0.05).

CONCLUSIONS

Our study demonstrates that the LOX gene is extensively expressed in diabetic nephropathy,with significantly upregulated expression and accompanying notable physiological markers such as TNF-α, IL-6, fasting blood glucose, and 24-hour urine microalbumin. The observed alterations indicate that the LOX gene has a potential biomarker function in the advancement of the disease.

(-)-Epicatechin ameliorates type 2 diabetes mellitus by reshaping the gut microbiota and Gut-Liver axis in GK rats

As one of the most abundant plant polyphenols in the human diet, (-)-epicatechin (EC) can improve insulin sensitivity and regulate glucose homeostasis. However, the primary mechanisms involved in EC anti-T2DM benefits remain unclear. The present study explored the effects of EC on the gut microbiota and liver transcriptome in type 2 diabetes mellitus (T2DM) Goto-Kakizaki rats for the first time. The findings showed that EC protected glucose homeostasis, alleviated systemic oxidative stress, relieved liver damage, and increased serum insulin. Further investigation showed that EC reshaped gut microbiota structure, including inhibiting the proliferation of lipopolysaccharide (LPS)-producing bacteria and reducing serum LPS. In addition, transcriptome analysis revealed that the insulin signaling pathway may be the core pathway of the EC anti-T2DM effect. Therefore, EC may modulate the gut microbiota and liver insulin signaling pathways by the gut-liver axis to alleviate T2DM. As a diet supplement, EC has promising potential in T2DM prevention and treatment.

Extraction methods, multiple biological activities, and related mechanisms of Momordica charantia polysaccharide: A review

Momordica Charantia Polysaccharide (MCP) is a key bioactive compound derived from bitter melon fruit. This review summarizes the advancements in MCP research, including extraction techniques, biological activities, and mechanisms. MCP can be extracted using various methods, and has demonstrated hypoglycemic, antioxidant, anti-inflammatory, and immunoregulatory effects. Research suggests that MCP may regulate metabolic enzymes, oxidative stress reactions, and inflammatory pathways. The review highlights the potential applications of MCP in areas such as anti-diabetes, antioxidant, anti-inflammatory, and immunoregulatory research. Future research should focus on elucidating the molecular mechanisms of MCP and optimizing extraction methods. This review provides a foundation for further research and utilization of MCP.

A novel heat-stable angiotensin-converting enzyme zinc-binding motif inhibitory peptide identified from corn silk

ETHNOPHARMACOLOGICAL RELEVANCE

Hypertension is the most common and chronic severe health problem globally. Corn silk (CS), the silky fibers of corn (Zea mays L.), has a long history of traditional usage as a remedy for edema and hypertension.

AIM OF THE STUDY

The aim of the study was to explore the underlying mechanism by which CS exerts its anti-hypertensive effects and investigate the presence of bioactive molecules in CS aqueous extract.

MATERIALS AND METHODS

We analyzed the effects of boiling water extract of CS on angiotensin-converting enzyme (ACE) activities, the critical enzyme involved in the regulation of blood pressure. ACE inhibitory peptides from CS extract were identified using proteomics and bioinformatics tools. The binding interfaces between these peptides and ACE were defined by hydrogen-deuterium exchange mass spectrometry (HDX-MS). Subsequently, the anti-hypertensive effects of peptides were further investigated in spontaneously hypertensive rats (SHR).

RESULTS

Our data showed that CS extract exhibited dose-dependent inhibition of ACE activity. Liquid chromatography-tandem mass spectrometry identified a heat-stable peptide bank with 1313 distinct peptide fragments within the CS boiling water extract. Among these, CS-1 (LVPGWTKPICIGR) was selected through PeptideRanker and BIOPEP-UWM analyses. In vitro ACE inhibitory assays confirmed that CS-1 exhibited dose-dependent ACE inhibition, with IC50 values of 10.32 ± 0.41 μmol/L (using HHL as the substrate) and 13.74 ± 1.87 μmol/L (using ZFHL as the substrate). Oral administration of CS-1 led to a significant dose-dependent reduction in blood pressure, with the maximal decrease (42.33 ± 13.08 mmHg) occurring 0.5 h after ingestion. HDX-MS analysis revealed that CS-1 interacted with the zinc-binding motif of ACE, and hydrogen bond interactions were predicted between CS-1 and specific residues, including His361 in the N-domain, as well as His382, Gly386, and His387 in the C-domain of ACE. These findings suggested that the interaction of CS-1 with the residues in the zinc-binding motif of ACE led to ACE activity inhibition and a subsequent decrease in blood pressure in rats.

CONCLUSIONS

A novel heat-stable ACE inhibitory peptide, which interacted with the zinc-binding motif of ACE and reduced blood pressure in SHR, was identified in the CS extract. The presence of ACE inhibitory peptides in the CS extract supports its traditional use in ethnopharmacology for hypertension.

New insights into the bioactive polysaccharides, proteins, and triterpenoids isolated from bitter melon (Momordica charantia) and their relevance for nutraceutical and food application: A review

The recent trend in infectious diseases and chronic disorders has dramatically increased consumers' interest in functional foods. As a result, the research of bioactive ingredients with potential for nutraceutical and food application has rapidly become a topic of interest. In this optic, the plant Momordica charantia (M. charantia) has recently attracted the most attention owing to its numerous biological properties including anti-diabetic, anti-obesity, anti-inflammatory, anti-cancers among others. However, the current literature on M. charantia has mainly been concerned with the plant extract while little is known on the specific bioactive compounds responsible for the plant's health benefits. Hence, the present review aims to provide a comprehensive overview of the recent research progress on bioactives isolated from M. charantia, focusing on polysaccharides, proteins, and triterpenoids. Thus, this review provides an up-to-date account of the different extraction methods used to isolate M. charantia bioactives. In addition, the structural features and biological properties are presented. Moreover, this review discusses the current and promising applications of M. charantia bioactives with relevance to the nutraceutical and food industries. The information provided in this review will serve as a theoretical basis and practical support for the formulation of products enriched with M. charantia bioactives.

Immunomodulatory effects and associated mechanisms of Momordica charantia and its phytochemicals

Momordica charantia L. (M. charantia), which is a member of the Cucurbitaceae family and widely distributed in tropical and subtropical regions, has been consumed as a vegetable and also used as herbal medicine for thousands of years worldwide.