Beneficial effects of mung bean seed coat on the prevention of high-fat diet-induced obesity and the modulation of gut microbiota in mice

Gut microbiota affects obesity susceptibility in mice through gut metabolites

Introduction

It is well-known that different populations and animals, even experimental animals with the same rearing conditions, differ in their susceptibility to obesity. The disparity in gut microbiota could potentially account for the variation in susceptibility to obesity. However, the precise impact of gut microbiota on gut metabolites and its subsequent influence on susceptibility to obesity remains uncertain.

Methods

In this study, we established obesity-prone (OP) and obesity-resistant (OR) mouse models by High Fat Diet (HFD). Fecal contents of cecum were examined using 16S rDNA sequencing and untargeted metabolomics. Correlation analysis and MIMOSA2 analysis were used to explore the association between gut microbiota and intestinal metabolites.

Results

After a HFD, gut microbiota and gut metabolic profiles were significantly different between OP and OR mice. Gut microbiota after a HFD may lead to changes in eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), a variety of branched fatty acid esters of hydroxy fatty acids (FAHFAs) and a variety of phospholipids to promote obesity. The bacteria g_Akkermansia (Greengene ID: 175696) may contribute to the difference in obesity susceptibility through the synthesis of glycerophosphoryl diester phosphodiesterase (glpQ) to promote choline production and the synthesis of valyl-tRNA synthetase (VARS) which promotes L-Valine degradation. In addition, gut microbiota may affect obesity and obesity susceptibility through histidine metabolism, linoleic acid metabolism and protein digestion and absorption pathways.

Serotonin Transporter (SERT) Expression Modulates the Composition of the Western-Diet-Induced Microbiota in Aged Female Mice

Background. The serotonin transporter (SERT), highly expressed in the gut and brain, is implicated in metabolic processes. A genetic variant of the upstream regulatory region of the SLC6A4 gene encoding SERT, the so-called short (s) allele, in comparison with the long (l) allele, results in the decreased function of this transporter, altered serotonergic regulation, an increased risk of psychiatric pathology and type-2 diabetes and obesity, especially in older women. Aged female mice with the complete (Sert-/-: KO) or partial (Sert+/-: HET) loss of SERT exhibit more pronounced negative effects following their exposure to a Western diet in comparison to wild-type (Sert+/+: WT) animals. Aims. We hypothesized that these effects might be mediated by an altered gut microbiota, which has been shown to influence serotonin metabolism. We performed V4 16S rRNA sequencing of the gut microbiota in 12-month-old WT, KO and HET female mice that were housed on a control or Western diet for three weeks. Results. The relative abundance of 11 genera was increased, and the abundance of 6 genera was decreased in the Western-diet-housed mice compared to the controls. There were correlations between the abundance of Streptococcus and Ruminococcaceae_UCG-014 and the expression of the pro-inflammatory marker Toll-like-Receptor 4 (Tlr4) in the dorsal raphe, as well as the expression of the mitochondrial activity marker perixome-proliferator-activated-receptor-cofactor-1b (Ppargc1b) in the prefrontal cortex. Although there was no significant impact of genotype on the microbiota in animals fed with the Control diet, there were significant interactions between diet and genotype. Following FDR correction, the Western diet increased the relative abundance of Intestinimonas and Atopostipes in the KO animals, which was not observed in the other groups. Erysipelatoclostridium abundance was increased by the Western diet in the WT group but not in HET or KO animals. Conclusions. The enhanced effects of a challenge with a Western diet in SERT-deficient mice include the altered representation of several gut genera, such as Intestinimonas, Atopostipes and Erysipelatoclostridium, which are also implicated in serotonergic and lipid metabolism. The manipulation of these genera may prove useful in individuals with the short SERT allele.

Lacto-Fermented and Unfermented Soybean Differently Modulate Serum Lipids, Blood Pressure and Gut Microbiota during Hypertension

Soy consumption may reduce hypertension but the impact of food processing on the antihypertensive effect is unclear. Hence, we ascertained the effects of lacto-fermented (FSB) and unfermented soybean (USB) consumption on serum atherogenic lipids, hypertension and gut microbiota of spontaneous hypertensive rats (SHR). FSB displayed a strong in vitro angiotensin converting enzyme (ACE) inhibitory ability of 70 ± 5% while USB inhibited 5 ± 3% of the enzyme activity. Consumption of USB reduced serum ACE activity by 19.8 ± 12.85 U while FSB reduced the enzyme activity by 47.6 ± 11.35 U, respectively. FSB significantly improved cholesterol levels and reduced systolic and diastolic blood pressures by 14 ± 3 mmHg and 10 ± 3 mmHg, respectively, while USB only had a marginal impact on blood pressure. Analysis of FSB showed the abundance of ACE inhibitory peptides EGEQPRPFPFP and AIPVNKP (which were absent in USB) and 30 phenolic compounds (only 12 were abundant in USB). Feeding SHR with FSB promoted the growth of Akkermansia, Bacteroides, Intestinimonas, Phocaeicola, Lactobacillus and Prevotella (short chain fatty acid producers) while USB promoted only Prevotellamassilia, Prevotella and Intestimonas levels signifying the prebiotic ability of FSB. Our results show that, relative to USB, FSB are richer in bioactive compounds that reduce hypertension by inhibiting ACE, improving cholesterol levels and mitigating gut dysbiosis.

Gut Microbiota Dysbiosis Induced by a High-Fat Diet Increases Susceptibility to Atrial Fibrillation

BACKGROUND

Obesity is a significant risk factor for atrial fibrillation (AF), and the gut microbiota is closely related to obesity-induced diseases. However, whether the gut microbiota is involved in regulating obesity-induced AF has not been studied. This study investigated whether gut microbiota dysbiosis affects obesity-related AF.

METHODS

Fecal microbes derived from normal diet (ND)-fed and high-fat diet (HD)-fed mice were transplanted into those fed normally. Morphologic, biochemical, functional, histologic, electrophysiological studies, molecular analysis, 16S rRNA gene amplicon sequencing, and RNA-sequencing were performed.

RESULTS

Transplantation of the HD gut microbes in ND-maintained (THD) mice led to a significant increase in the susceptibility to AF. Gut microbiota analysis showed a significant increase in Desulfovibrionaceae, which generated metabolic endotoxemia in THD mice. Transplantation with HD microbes also resulted in significantly increased levels of circulating lipopolysaccharide (LPS), significant disruption in the histologic architecture of the intestinal tissue, and significantly increased proinflammatory cytokines in the left atrium, indicating that atrial inflammation likely contributed to AF susceptibility. RNA-sequencing showed that the THD group had enhanced activation of ferroptosis and TLR4/NF-κB/NLRP3 inflammasome signalling pathway. Inhibiting the ferroptosis or NLRP3 inflammasome signalling pathway significantly improved atrial fibrosis and reduced susceptibility to obesity-related gut dysbiosis-induced AF.

CONCLUSIONS

This study provides evidence showing an original causal role of gut microbiota dysbiosis in the pathogenesis of obesity-related AF, which showed elevated LPS and dysregulation of atrial pathologic remodelling by activating ferroptosis and the TLR4/NF-κB/NLRP3 inflammasome signalling pathway.

Eugenol, A Major Component of Clove Oil, Attenuates Adiposity and Modulates Gut Microbiota in High-Fat Diet-fed Mice

SCOPE

Eugenol (EU), the major aromatic compound derived from clove oil, is being focused recently due to its potential in preventing several chronic conditions. Herein, we aimed to evaluate the potential of EU in obesity prevention and to delineate the mechanisms involved.

METHODS AND RESULTS

Five-week-old male C57BL/6J mice were fed with high-fat diet (HFD) or HFD supplemented with EU (0.2%, w/w) for 13 weeks. EU significantly reduced obesity-related indexes including final body weight, body weight gain, adipocyte size, visceral fat-pad weight, and fasting blood glucose. EU prevented HFD-induced gut dysbiosis, as indicated by the increase of Firmicutes and decrease of Desulfobacterota at phylum level, and the increase of Dubosiella, Blautia, unclassified_f_Oscillospiraceae, and unclassified_f_Ruminococcaceae, and the decrease of Alistipes, Alloprevotella, and Bilophila at genus level. Notably, the obesity-related indexes were positively correlated with the relative abundances of Bacteroides, unclassified_f_Lachnospiraceae, Colidextribacter, and Bilophila, and negatively correlated with the relative abundances of norank_f_Muribaculaceae and Lachnospiraceae_NK4A136_group. Moreover, the preventive effects of EU on obesity were accompanied by the transcriptomic reprogramming of white adipose tissue.

CONCLUSION

These findings demonstrated that EU prevents the HFD-induced adiposity and modulates gut dysbiosis, and highlighted the potential of EU in obesity intervention as a functional dietary supplement. This article is protected by copyright. All rights reserved.

An update on nutritional profile, phytochemical compounds, health benefits, and potential applications in the food industry of pulses seed coats: A comprehensive review

Pulses, as a sustainable source of nutrients, are an important choice for human diets, but vast quantities of seed coats generated in pulses processing are usually discarded or used as low-value ruminant feed. It has been demonstrated that pulses seed coats are excellent sources of dietary nutrients and phytochemicals with potential health benefits. With growing interest in the sustainable use of resources and the circular economy, utilization of pulses seed coats to recover these valuable components is a core objective for their valorization and an important step toward agricultural sustainability. This review comprehensively provides a comprehensive insight on the nutritional and phytochemical profiles presented in pulses seed coats and their health benefits obtained from the findings of in vitro and in vivo studies. Furthermore, in the food industry, pulses seed coats can be acted as potential food ingredients with nutritional, antioxidant and antimicrobial characteristics or as the matrix or active components of films for food packaging and edible coatings. A better understanding of pulses seed coats may provide a reference for increasing the overall added value and realizing the pulses' sustainable diets.

Gut Microbiota Modulation, Anti-Diabetic and Anti-Inflammatory Properties of Polyphenol Extract from Mung Bean Seed Coat (Vigna radiata L.)

The present study investigated the gut health, anti-diabetic, and anti-inflammatory activities of mung bean seed coat extract (MSE). MSE was obtained by pressurized liquid extraction (PLE) using 50% ethanol as the extracting solvent. After 24 h of in vitro human fecal fermentation, MSE exhibited higher productions of total short-chain fatty acids (SCFA) than those of the control group (CON) and other polyphenol-rich substrates, including gallic acid (GA) and vitexin (VIT) (p > 0.05), but still lower than the fructo-oligosaccharide (FOS). In 16S-rRNA next-generation sequencing, MSE regulated the composition of gut microbiota by stimulating the growth of the beneficial bacteria Enterococcus, Ruminococcus, Blautia, and Bacteroides and decreasing the growth of the potential pathogenic bacteria Escherichia-Shigella. Similarly, qPCR showed increased numbers of Bifidobacterium, Lactobacillus, Faecalibacterium prausnitzii, and Prevotella, compared with those of CON (p < 0.05). MSE also reduced reactive oxygen species and increased glucose uptake in insulin-resistant HepG2 cells dose-dependently. The anti-inflammatory activity of MSE was observed in LPS-stimulated THP-1 monocytes with the reduction of TNFα, IL-1β, IL-6, and IL-8 genes. The data demonstrated the potential applications of MSE as a dietary supplement with gut health benefits and its ability to mitigate diabetes and inflammatory-related diseases.

Pomegranate peel anthocyanins prevent diet-induced obesity and insulin resistance in association with modulation of the gut microbiota in mice

PURPOSE

Pomegranate peels are rich in anthocyanins. The present study aimed to explore the beneficial effects of pomegranate peel anthocyanins (PPA) on obesity and gut microbiota in mice with high-fat diet (HFD)-induced obesity.

METHODS

Specific pathogen-free (SPF) male C57BL/6 J mice were randomly divided into three groups and fed with low-fat diet (LFD, 10% fat energy), HFD (45% fat energy), or HFD supplemented with PPA by intragastric administration for 15 weeks. Body weight and food intake were monitored weekly. The obesity-related biochemical indexes and hepatic gene expression levels were determined. The compositions of the gut microbiota were analyzed by 16S rRNA sequencing, and the association between the gut microbiota and obesity-related indicators was investigated by Spearman correlation analysis.

RESULTS

The results showed that the body weight gain, steatosis scores and insulin resistance index in the PPA group decreased by 27.46%, 56.25%, and 46.07%, respectively, compared to the HFD group. Gene expression analysis indicated that PPA supplement improved the genes expression profiles involved in glucose and lipid metabolism compared with the mice fed HFD alone. Meanwhile, PPA significantly changed the composition of the gut microbiota, which were closely correlated with the obesity-related biomarkers.

CONCLUSION

This study suggested that PPA could be a beneficial treatment option for alleviating HFD-induced obesity and related metabolic disorders by targeting microbiota and lipid metabolism.

Suppression of high-fat-diet-induced obesity in mice by dietary folic acid supplementation is linked to changes in gut microbiota

PURPOSE

To investigate whether the effects of dietary folic acid supplementation on body weight gain are mediated by gut microbiota in obesity.

METHODS

Male C57 BL/6J conventional (CV) and germ-free (GF) mice both aged three to four weeks were fed a high-fat diet (HD), folic acid-deficient HD (FD-HD), folic acid-supplement HD (FS-HD) and a normal-fat diet (ND) for 25 weeks. Faecal microbiota were analyzed by 16S rRNA high-throughput sequencing, and the mRNA expression of genes was determined by the real-time RT-PCR. Short-chain fatty acids (SCFAs) in faeces and plasma were measured using gas chromatography-mass spectrometry.

RESULTS

In CV mice, HD-induced body weight gain was inhibited by FS-HD, accompanied by declined energy intake, smaller white adipocyte size, and less whitening of brown adipose tissue. Meanwhile, the HD-induced disturbance in the expression of fat and energy metabolism-associated genes (Fas, Atgl, Hsl, Ppar-α, adiponectin, resistin, Ucp2, etc.) in epididymal fat was diminished, and the dysbiosis in faecal microbiota was lessened, by FS-HD. However, in GF mice with HD feeding, dietary folic acid supplementation had almost no effect on body weight gain and the expression of fat- and energy-associated genes. Faecal or plasma SCFA concentrations in CV and GF mice were not altered by either FD-HD or FS-HD feeding.

CONCLUSION

Dietary folic acid supplementation differently affected body weight gain and associated genes' expression under HD feeding between CV and GF mice, suggesting that gut bacteria might partially share the responsibility for beneficial effects of dietary folate on obesity.

Protective mechanism of mung bean coat against hyperlipidemia in mice fed with a high-fat diet: insight from hepatic transcriptome analysis

Mung bean coat (MBC) is a good source of dietary fibre and phenolic compounds with medical properties, and can alleviate metabolic diseases. In the present study, the effects of MBC on high fat diet (HFD)-induced hyperlipidemia mice were evaluated, and the underlying mechanisms of MBC against hyperlipidemia from hepatic transcriptional analysis were explored. Four groups of mice were fed a normal control diet or a HFD with or without MBC supplementation (6%, w/w) for 12 weeks. The results demonstrated that MBC supplementation could effectively alleviate HFD-induced obese symptoms, such as body weight gain and white adipose tissue accumulation. Notably, the serum lipid profiles, including total triglyceride, total cholesterol, and low-density lipoprotein cholesterol, were significantly lowered, accompanied by a significant improvement in hepatic steatosis. RNA-sequencing analysis indicated 1126 differential expression genes responding to MBC supplementation, and the PPAR signaling pathway was significantly enriched. Furthermore, MBC supplementation could significantly upregulate the transcriptional expression of lipid transformation (lipidolysis)-related genes (Cpt1b, Cyp7a1, and PPAR-α) and downregulate the transcriptional expression of lipid synthesis-related genes (Scd1, Cd36, and PPAR-γ) to protect against the HFD-induced hyperlipidemia, and they were confirmed by qRCR and western blotting validation. Taken together, the present study provides valuable information for understanding the curative effects and action mechanism of MBC in alleviating hyperlipidemia, and thus may contribute to the development and application of MBC as functional foods or dietary supplement to protect against hyperlipidemia.

Enteromorpha prolifera polysaccharide-zinc complex modulates the immune response and alleviates LPS-induced intestinal inflammation via inhibiting the TLR4/NF-κB signaling pathway

Enteromorpha prolifera polysaccharide-zinc (EP-Zn), a kind of polysaccharide-zinc complex, has been shown to improve the immune response and reduce the inflammatory factors in weaned piglets. Yet, the molecular mechanism remains unclear. The present study was conducted to investigate the immunomodulating activity and anti-inflammatory mechanism of EP-Zn in mice. Different doses (350 mg kg^-1, 700 mg kg^-1, 1050 mg kg^-1 and 1400 mg kg^-1) of EP-Zn were administered to C57BL/6J mice for 28 days. The results showed that under physiological conditions, 350 mg kg^-1 EP-Zn stimulated cytokine (TNF-α, IL-1β, IL-6 and IL-10) secrection, regulated the intestinal microbiota, and reduced the levels of short-chain fatty acids (SCFAs) (acetic acid and propionic acid). In addition, in the LPS-induced inflammation model, EP-Zn pretreatment effectively alleviated LPS-induced shortening of colonic length and increased MPO and DAO contents, improved intestinal physical barrier function by modulating mucosal structure, and attenuated intestinal inflammation via inhibiting the TLR4/NF-κB signaling pathway. These findings suggested that EP-Zn exerted immunomodulatory and anti-inflammatory activities under physiological and inflammatory conditions, respectively.

Mung Bean Protein Suppresses Undernutrition-Induced Growth Deficits and Cognitive Dysfunction in Rats via Gut Microbiota-TLR4/NF-kB Pathway

Early undernutrition has been found to be closely associated with subsequent neurodevelopment. However, studies examining crude growth in terms of body weight/tail length cannot clarify how diets might mediate associations between the gut microbiota and cognitive dysfunction. In the present study, Sprague-Dawley (SD) rats were fed a 7% protein diet and mung bean protein diet (MBPD) for 6 weeks to assess central nervous system functions. Bifidobacterium longum subsp, Alloprevotella, and Lactobacillus were significantly altered after supplementary MBPD. Additionally, tryptophan, tyrosine, and glycine significantly restored in the brain, and the choline system also improved. Moreover, mung bean supplementation also upregulated expression of the brain-derived neurotrophic factor, postsynaptic density 95 protein (PSD95), synaptosome-associated protein 25 (SNAP25), downregulated toll-like receptor 4 (TLR4), and nuclear factor kB (NF-kB). Metabolites in the serum also underwent changes. Together, these results showed that malnutrition perturbed neurodevelopment, while MBPD reversed this trend.

Dietary supplementation with mung bean coat alleviates the disorders in serum glucose and lipid profile and modulates gut microbiota in high-fat diet and streptozotocin-induced prediabetic mice

As amajor by-product of mung bean processing, mung bean coat (MBC), which is rich in polyphenols and dietary fiber, is deemed to be mainly responsible for the health benefits of mung bean. However, its beneficial effects on the hyperglycemia, hyperlipidemia, and gut microbiota composition in prediabetic mice is not fully understood. The objective of this study was to investigate the efficacy of MBC in alleviating high-fat diet and streptozotocin-induced prediabetes. Herein, compared with the model control, dietary supplementation with MBC (3%, w/w) for 12 weeks significantly decreased the fasting blood glucose (24.60%), total cholesterol (15.72%), triglyceride (14.41%), and low-density lipoprotein cholesterol (22.45%). Furthermore, the improvements in glucose tolerance were reflected in the reduction of the area under the curve (AUC) and incremental AUC by approximately 23.08% and 51.18%, respectively. 16S rRNA gene sequencing of fecal microbiota suggested that MBC promoted the enrichment of beneficial bacteria (Roseburia and Bifidobacterium) and the production of short-chain fatty acids. All of the results from this study provided a scientific reference for avoiding the functional ingredients waste of MBC and expanding its application value.

Beneficial effects of mung bean seed coat on the prevention of high-fat diet-induced obesity and the modulation of gut microbiota in mice

PURPOSE

Our recent study has reported that whole mung bean showed better beneficial effects on high-fat diet (HFD)-induced obesity and gut microbiota disorders when compared with the decorticated mung bean at the same intervention dose level, suggesting that the mung bean seed coat (MBC) may play a crucial role in its health benefits. This study aims to investigate whether MBC has beneficial benefits on the prevention of HFD-induced obesity and the modulation of gut microbiota in mice when it was supplemented in HFD.

METHODS

Herein, male C57BL/6 J mice were fed with normal control diet, HFD, and HFD supplemented with MBC (3-6%, w/w) for 12 weeks. The changes in physiological, histological, biochemical parameters, serum endotoxin, proinflammatory cytokines, and gut microbiota composition of mice were determined to assess the ability of MBC to alleviate HFD-induced obesity and modulate gut microbiota disorders in mice.

RESULTS

MBC supplementation exhibited significant reductions in the HFD-induced adiposity, fat accumulation, serum lipid levels, lipopolysaccharide, and proinflammatory cytokines concentrations (P < 0.05), which was accompanied by improvements in hepatic steatosis and adipocyte size. Especially, the elevated fasting blood glucose and insulin resistance were also significantly improved by MBC supplementation (P < 0.05). Furthermore, high-throughput sequencing of the 16S rRNA gene revealed that MBC could normalize HFD-induced gut microbiota dysbiosis. MBC not only could promote the bloom of Akkermansia, but also restore several HFD-dependent taxa (Blautia, Ruminiclostridium_9, Bilophila, and unclassified_f_Ruminococcaceae) back to normal status, co-occurring with the decreases in obesity-related indices.

CONCLUSIONS

This study provides evidence that MBC may be mainly responsible for the beneficial effects of whole mung bean on preventing the HFD-induced changes, thus enlarging the application value of MBC.