Dietary Genistein Reduces Methylglyoxal and Advanced Glycation End Product Accumulation in Obese Mice Treated with High-Fat Diet

Dietary dicarbonyl compounds exacerbated immune dysfunction and hepatic oxidative stress under high-fat diets in vivo

High-fat diets (HFDs) predispose to obesity and liver dysfunctions, and α-dicarbonyl compounds (α-DCs) present in highly processed foods are also implicated in relevant pathological processes. However, the synergistic harmful effects of α-DCs co-administered with HFDs remain to be elucidated. In this study, 6-week-old C57BL/6 mice were fed with a HFD co-administered with 0.5% methylglyoxal (MGO)/glyoxal (GO) in water for 8 weeks, and multi-omics approaches were employed to investigate the underlying toxicity mechanisms. The results demonstrated that the MGO intervention with a HFD led to an increased body weight and blood glucose level, accompanied by the biological accumulation of α-DCs and carboxymethyl-lysine, as well as elevated serum levels of inflammatory markers including IL-1β, IL-6, and MIP-1α. Notably, hepatic lesions were observed in the MGO group under HFD conditions, concomitant with elevated levels of malondialdehyde. Transcriptomic analysis revealed enrichment of pathways and differentially expressed genes (DEGs) associated with inflammation and oxidative stress in the liver. Furthermore, α-DC intervention exacerbated gut microbial dysbiosis in the context of a HFD, and through Spearman correlation analysis, the dominant genera such as Fusobacterium and Bacteroides in the MGO group and Colidextribacter and Parabacteroides in the GO group were significantly correlated with a set of DEGs involved in inflammatory and oxidative stress pathways in the liver. This study provides novel insights into the healthy implications of dietary ultra-processed food products in the context of obesity-associated disorders.

Scavenging Glyoxal and Methylglyoxal by Synephrine and Neohesperidin from Flowers of Citrus aurantium L. var. amara Engl. in Mice and Humans

There is considerable research evidence that α-dicarbonyl compounds, including glyoxal (GO) and methylglyoxal (MGO), are closely related to many chronic diseases. In this work, after comparison of the capture capacity, reaction pathway, and reaction rate of synephrine (SYN) and neohesperidin (NEO) on GO/MGO in vitro, experimental mice were administrated with SYN and NEO alone and in combination. Quantitative data from UHPLC-QQQ-MS/MS revealed that SYN/NEO/HES (hesperetin, the metabolite of NEO) could form the GO/MGO-adducts in mice (except SYN-MGO), and the levels of GO/MGO-adducts in mouse urine and fecal samples were dose-dependent. Moreover, SYN and NEO had a synergistic scavenging effect on GO in vivo by promoting each other to form more GO adducts, while SYN could promote NEO to form more MGO-adducts, although it could not form MGO-adducts. Additionally, human experiments showed that the GO/MGO-adducts of SYN/NEO/HES found in mice were also detected in human urine and fecal samples after drinking flowers of Citrus aurantium L. var. amara Engl. (FCAVA) tea using UHPLC-QTOF-MS/MS. These findings provide a novel strategy to reduce endogenous GO/MGO via the consumption of dietary FCAVA rich in SYN and NEO.

Underlying mechanisms and molecular targets of genistein in the management of type 2 diabetes mellitus and related complications

Diabetes mellitus (DM) is a chronic metabolic disease caused by a complex interaction of genetic and environmental factors and is characterized by persistent hyperglycemia. Long-term hyperglycemia can cause macrovascular and microvascular damage, and compromise the heart, brain, kidney, peripheral nerves, eyes and other organs, leading to serious complications. Genistein, a phytoestrogen derived from soybean, is known for its various biological activities and therapeutic properties. Recent studies found that genistein not only has hypoglycemic activity but can also decrease insulin resistance. In addition, genistein has particular activity in the prevention and treatment of diabetic complications, such as nephropathy, cardiovascular disease, osteoarthrosis, encephalopathy and retinopathy. Therefore, the purpose of this review is to summarize the latest medical research and progress of genistein in DM and related complications and highlights its potential molecular mechanisms and therapeutic targets. Meanwhile, evidence is provided for the development and application of genistein as a potential drug or functional food in the prevention and treatment of diabetes and its related complications.

Protective effects of genistein on the production performance and lipid metabolism disorders in laying hens with fatty liver hemorrhagic syndrome by activation of the GPER-AMPK signaling pathways

The aim of this study was to evaluate the beneficial effects and potential mechanisms of genistein (GEN) on production performance impairments and lipid metabolism disorders in laying hens fed a high-energy and low-protein (HELP) diet. A total of 120 Hy-line Brown laying hens were fed with the standard diet and HELP diet supplemented with 0, 50, 100, and 200 mg/kg GEN for 80 d. The results showed that the declines in laying rate (P < 0.01), average egg weight (P < 0.01), and egg yield (P < 0.01), and the increase of the ratio of feed to egg (P < 0.01) induced by HELP diet were markedly improved by 100 and 200 mg/kg of GEN treatment in laying hens (P < 0.05). Moreover, the hepatic steatosis and increases of lipid contents (P < 0.01) in serum and liver caused by HELP diet were significantly alleviated by treatment with 100 and 200 mg/kg of GEN in laying hens (P < 0.05). The liver index and abdominal fat index of laying hens in the HELP group were higher than subjects in the control group (P < 0.01), which were evidently attenuated by dietary 50 to 200 mg/kg of GEN supplementation (P < 0.05). Dietary 100 and 200 mg/kg of GEN supplementation significantly reduced the upregulations of genes related to fatty acid transport and synthesis (P < 0.01) but enhanced the downregulations of genes associated with fatty acid oxidation (P < 0.01) caused by HELP in the liver of laying hens (P < 0.05). Importantly, 100 and 200 mg/kg of GEN supplementation markedly increased G protein-coupled estrogen receptor (GPER) mRNA and protein expression levels and activated the AMP-activated protein kinase (AMPK) signaling pathway in the liver of laying hens fed a HELP diet (P < 0.05). These data indicated that the protective effects of GEN against the decline of production performance and lipid metabolism disorders caused by HELP diet in laying hens may be related to the activation of the GPER-AMPK signaling pathways. These data not only provide compelling evidence for the protective effect of GEN against fatty liver hemorrhagic syndrome in laying hens but also provide the theoretical basis for GEN as an additive to alleviate metabolic disorders in poultry.

Genistein suppresses microglial activation and inhibits apoptosis in different brain regions of hypoxia-exposed mice model of amnesia

Genistein (GE) or 4',5,7-trihydroxyflavone, a plant derived isoflavone, is a biologically active compound having several beneficial properties. Studies showed that GE possesses anti-neoplastic, anti-tumor, anti-helminthic, anti-oxidant, and anti-inflammatory activities. Herein, we investigated the neuroprotective effects of GE in a mouse model of hypoxia-induced amnesia. Mice were exposed to hypoxic conditions (10% O2) in a designated hypoxia chamber and co-treated with GE (10, 20, or 30 mg/kg) for 4 weeks. Following this, behavioral tests were performed to evaluate memory performance. We assessed microglial activation in the hippocampus, amygdala, and pre-frontal cortex (PFC) regions by evaluating the Iba-1 and GFAP transcript levels, and MIP-1β, Cox-2, and IL6 protein levels. Apoptosis was assessed by evaluating Bax, BAD, and Bcl-2 mRNA levels, and caspase-3 activity. To uncover the underlying molecular mechanism, we evaluated the levels of Nrf2, HO-1, and NQO1 in different brain regions of mice from all groups. Results showed that hypoxia-exposed mice have reduced performance in the behavioral tests and GE treatment enhanced the memory performance in hypoxia-exposed mice. Moreover, hypoxia-exposed mice showed increased expression of microglial activation markers and enhanced apoptosis in the hippocampus, amygdala, and PFC. GE treatment suppressed microglial activation and prevented apoptosis in the brain of hypoxia-exposed mice. Furthermore, hypoxia-exposure reduced the expression of Nrf2, NQO1, and HO-1 while GE treatment ameliorated this decrease in different regions of hypoxia-exposed mice brain. In conclusion, GE prevents cognitive dysfunction by suppressing microglial activation and inhibiting apoptosis in the hypoxia-exposed mice brain.

Natural polyphenols: a potential prevention and treatment strategy for metabolic syndrome

Metabolic syndrome (MS) is the term for a combination of hypertension, dyslipidemia, insulin resistance, and central obesity as factors leading to cardiovascular and metabolic disease. Epidemiological investigation has shown that polyphenol intake is negatively correlated with the incidence of MS. Natural polyphenols are widely found in cocoa beans, tea, vegetables, fruits, and some Chinese herbal medicines; they are a class of plant compounds containing a variety of phenolic structural units, which are potent antioxidants and anti-inflammatory agents in plants. Polyphenols are composed of flavonoids (such as flavanols, anthocyanidins, anthocyanins, isoflavones, etc.) and non-flavonoids (such as phenolic acids, stilbenes, and lignans). Modern pharmacological studies have proved that polyphenols can reduce blood pressure, improve lipid metabolism, lower blood glucose, and reduce body weight, thereby preventing and improving MS. Due to the unique characteristics and potential development and application value of polyphenols, this review summarizes some natural polyphenols that could treat MS, including their chemical properties, plant sources, and pharmacological action against MS, to provide a basis for the further study of polyphenols in MS.

Inonotus hispidus Protects against Hyperlipidemia by Inhibiting Oxidative Stress and Inflammation through Nrf2/NF-κB Signaling in High Fat Diet Fed Mice

Obesity is frequently associated with dysregulated lipid metabolism and lipotoxicity. Inonotus hispidus (Bull.: Fr.) P. Karst (IH) is an edible and medicinal parasitic mushroom. In this study, after a systematic analysis of its nutritional ingredients, the regulatory effects of IH on lipid metabolism were investigated in mice fed a high-fat diet (HFD). In HFD-fed mice, IH reversed the pathological state of the liver and the three types of fat and significantly decreased the levels of low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglycerides (TG), and leptin (LEP) and increased the level of high-density liptein cholesterol (HDL-C) in serum. Meanwhile, IH ameliorated liver damage by reducing alanine aminotransferase (ALT), aspartate aminotransferase (AST), interleukin (IL)-1β, IL-6, tumor necrosis factor-alpha (TNF-α), and plasminogen activator inhibitor-1 (PAI-1) levels in the liver and serum. Compared with HFD-fed mice, IH significantly modulated the gut microbiota, changed the relative abundances of microflora at different taxonomic levels, and regulated lipid levels. The results showed that 30 differential lipids were found. Results from Western blotting confirmed that IH regulated the nuclear factor erythroid-2 related factor 2 (Nrf2)/nuclear factor-kappa B (NF-κB) signaling pathway and oxidative stress. This study aimed to provide experimental evidence for the applicability of IH in obesity treatment.

Effects of Genistein and Exercise Training on Brain Damage Induced by a High-Fat High-Sucrose Diet in Female C57BL/6 Mice

In recent decades, a shift in the nutritional landscape to the Western-style diet has led to an unprecedented rise in the prevalence of obesity and neurodegenerative diseases. Consumption of a healthy diet and engaging in regular physical activity represents safe and affordable approaches known to mitigate the adverse consequences of the Western diet. We examined whether genistein treatment, exercise training, and a combination treatment (genistein and exercise training) mitigated the effects of a Western diet-induced by high-fat, high-sugar (HFHS) in brain of female mice. HFHS increased the amyloid-beta (Aβ) load and phosphorylation of tau, apoptosis, and decreased brain-derived neurotrophic factor (BDNF) levels. Exercise training and genistein each afforded modest protection on Aβ accumulation and apoptosis, and both increased BDNF. The greatest neuroprotective effect occurred with combination treatment. BDNF and all markers of Aβ accumulation, phosphorylation of tau, and apoptosis were improved with combined treatment. In a separate series of experiments, PC12 cells were exposed to high glucose (HG) and palmitate (PA) to determine cell viability with genistein as well as in the presence of tamoxifen, an estrogen receptor antagonist, to assess a mechanism of action of genistein on cell apoptosis. Genistein prevented the neurotoxic effects of HG and PA in PC12 cells and tamoxifen blocked the beneficial effects of genistein on apoptosis. Our results indicate the beneficial effects of genistein and exercise training on HFHS-induced brain damage. The benefits of genistein may occur via estrogen receptor-mediated pathways.

Trapping Methylglyoxal by Taxifolin and Its Metabolites in Mice

Trapping of methylglyoxal (MGO), an important precursor of advanced glycation end products (AGEs), is considered an effective therapy for alleviating AGE-induced chronic metabolic diseases. In this paper, taxifolin (Tax) was first found to effectively trap MGO by forming mono- and di-MGO adducts under in vitro conditions. In addition, the mechanism of trapping MGO by Tax was also studied in vivo. Tax was demonstrated to efficiently trap endogenous MGO via formation of mono-MGO adducts in urine and fecal samples of C57BL/6J mice after oral administration of Tax and MGO. Mono-MGO adducts of Tax metabolites, including methylated Tax, aromadendrin, quercetin, and isorhamnetin, were identified in C57BL/6J mice urine and fecal samples by ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS/MS). One mono-MGO-Tax was purified from the in vitro reaction mixture, and its structure was elucidated as 6-MGO-Tax based on the analysis of UHPLC-QTOF-MS/MS and detailed nuclear magnetic resonance (NMR) data. Quantification studies demonstrated that Tax and its metabolites trapped MGO in a dose-dependent manner in C57BL/6J mice urine and fecal samples. Furthermore, we also detected mono-MGO adducts of Tax and methylated Tax in urine and fecal samples of diabetic db/db mice after oral administration of Tax. Taken together, our results demonstrated that dietary Tax has the potential to detoxify MGO and treat AGE-associated chronic diseases.

Inhibition of Advanced Glycation End Product Formation in Rat Tail Tendons by Polydatin and p-Coumaric acid: an In Vitro Study

Advanced glycation end products (AGEs) formed through non-enzymatic glycosylation between a protein and sugar molecule are highly harmful to the human body. In hyperglycemic patients, AGE formation is more due to high glucose circulating in the blood, causing inter and intra molecular cross-linking of collagen leading to reduction of collagen elasticity. This cross-linked collagen develops resistance to matrix metalloproteinases leading to impaired collagen turnover. The aim of this work is to determine the anti-glycation effects of polydatin and p-coumaric acid in preventing collagen cross-linking by incubating rat tail tendons (RTTs) as collagen source in high glucose concentration (50 mM) for a week. The RTTs were then characterized for tensile strength, cross-linking efficiency, circular dichroism spectrometry, collagen, glucose, and aldehyde contents. Electrophoresis was carried out to evaluate the level of cross-linking in collagen and the results confirmed the ability of the drugs in preventing complex intermolecular cross-link formation induced by non-enzymatic glycosylation. CD data showed alteration in the secondary structure of collagen where AGE formation had occurred. More collagen was extracted by pepsin from RTTs treated with glucose alone (6.88 mg/10 mg tendon) when compared with drug-treated groups (4.25, 2.56 mg/10 mg tendon for polydatin and p-coumaric acid, respectively). Tensile strength (20.66% and 18.95%), cross-linking percentage (32.5% and 29.84%), and glucose content (2.3 and 1.8 mg/100 mg) of drug-treated groups were similar to the positive control (19.07%, 30.13%, and 2.61 mg/100 mg) thus proving the anti-glycation potential of the drugs. Hence, both polydatin and p-coumaric acid could play a pivotal role in preventing AGE formation.

Metabolic Profiling of Carbonyl Compounds for Unveiling Protective Mechanisms of Pueraria lobata against Diabetic Nephropathy by UPLC-Q-Orbitrap HRMS/MS Analysis

Carbonyl compounds play a critical role in the pathogenesis of diabetic nephropathy (DN). Pueraria lobata (PL), also known as "Kudzu", is a widely consumed functional food or nutraceutical and has shown promise in the prevention of diabetes and complications such as DN. To explore the beneficial effects and the underlying mechanisms of PL against DN, a new strategy for in-depth metabolic profiling of carbonyl compounds in DN mice plasma by chemical derivatization combined with UPLC-Q-Orbitrap high-resolution mass spectrometry (HRMS)/MS analysis was developed for the first time. Pharmacological evaluation revealed that PL extracts containing a total of 73 identified compounds could ameliorate kidney injury and regulate abnormal glycolipid metabolism. In metabolomics analysis, 19 carbonyl compounds with significant differences were identified between DN mice and normal mice. Moreover, 12 metabolites had a tendency to return to normal levels after PL treatment. Overall, PL exerts beneficial effects on DN by regulating abnormal glycolipid metabolism and carbonyl stress, and endogenous carbonyl compounds might serve as potential biomarkers for DN.

Dietary Quercetin Reduces Plasma and Tissue Methylglyoxal and Advanced Glycation End Products in Healthy Mice Treated with Methylglyoxal

BACKGROUND

Methylglyoxal (MGO), a precursor of advanced glycation end products (AGEs), has been linked to AGEs-associated diseases.

OBJECTIVES

This study investigated the efficacy and mechanisms of dietary quercetin in decreasing plasma and tissue concentrations of MGO and AGEs in MGO-administered mice.

METHODS

Male, 6-wk-old CD-1 mice were administered AIN-93G diet and water (Con) or 0.12% MGO in water (MGO) or MGO plus 0.2% (0.2Q) dietary quercetin for 1 wk (n = 5) (experiment 1), and water (Con), 0.12% MGO (MGO), or MGO plus 0.1% (0.1Q), 0.2% (0.2Q), or 0.4% (0.4Q) dietary quercetin for 6 wk (n = 10) (experiment 2). The plasma, kidney, and liver concentrations of MGO, quercetin, and isorhamnetin and their trapping adducts with MGO were determined by LC-MS, and AGE concentrations were measured by the fluorescent method. Furthermore, the expressions of glyoxalase I/II (GLO I/II) and aldose reductase (AR), MGO detoxification enzymes, were determined by Western blot. One-factor ANOVA and post hoc Dunnett's or Tukey's test were used to analyze the data.

RESULTS

After 1 wk of treatment, the MGO concentrations in plasma (20.2%) and kidney (29.9%) in 0.2Q mice were significantly lower than those in MGO mice. After 6 wk of treatment, the concentrations of MGO in the plasma (14.7-18.6%), kidney (20-20.8%), liver (15.4-18.6%), and tissue AGEs (28-36.8%) in 0.1Q, 0.2Q, and 0.4Q mice were significantly lower than those in MGO mice. The plasma concentrations of quercetin, isorhamnetin, and their MGO adducts were dose-dependently increased after quercetin administration. In addition, after 6 wk of quercetin administration, the expressions of GLO I/II and AR in the liver and kidney were significantly upregulated to promote MGO detoxification compared with MGO-treated mice.

CONCLUSIONS

Quercetin reduced plasma and tissue MGO concentrations and inhibited AGE formation by trapping MGO and regulating the MGO detoxification systems in MGO-administered healthy mice.

Advanced glycation end products (AGEs) and its receptor, RAGE, modulate age-dependent COVID-19 morbidity and mortality. A review and hypothesis

Coronavirus Disease 2019 (COVID-19), caused by the novel virus SARS-CoV-2, is often more severe in older adults. Besides age, other underlying conditions such as obesity, diabetes, high blood pressure, and malignancies, which are also associated with aging, have been considered risk factors for COVID-19 mortality. A rapidly expanding body of evidence has brought up various scenarios for these observations and hyperinflammatory reactions associated with COVID-19 pathogenesis. Advanced glycation end products (AGEs) generated upon glycation of proteins, DNA, or lipids play a crucial role in the pathogenesis of age-related diseases and all of the above-mentioned COVID-19 risk factors. Interestingly, the receptor for AGEs (RAGE) is mainly expressed by type 2 epithelial cells in the alveolar sac, which has a critical role in SARS-CoV-2-associated hyper inflammation and lung injury. Here we discuss our hypothesis that AGEs, through their interaction with RAGE amongst other molecules, modulates COVID-19 pathogenesis and related comorbidities, especially in the elderly.

Enteromorpha prolifera polysaccharide prevents high- fat diet-induced obesity in hamsters: A NMR-based metabolomic evaluation

Enteromorpha prolifera polysaccharide (EP) has been shown to exhibit hypolipidemic and hypoglycemic activities in various experimental models. Here, an ¹ H-NMR-based metabolomic study was conducted to explore the regulatory effects of EP on serum metabolic changes in obese hamsters. High-fat diet (HFD)-fed hamsters were orally administrated with EP (300, 450, or 600 mg/kg) once daily for 12 weeks. Compared with HFD-fed hamsters, EP treatment (450 and 600 mg/kg) significantly decreased the body weight (by 8.69 and 8.24%), liver weight (by 7.87 and 8.25%), epididymal white adipose tissue (by 19.54 and 17.26%), perirenal white adipose tissue (by 28.09 and 28.94%), serum total cholesterol (by 24.31 and 18.61%), triglyceride (by 30.64 and 31.38%), and low-density lipoprotein cholesterol (by 38.26 and 36.30%), respectively. In addition, EP intervention also significantly decreased hepatic cholesterol (by 23.20, 38.16, and 34.57%) and triglyceride content (by 17.78, 41.47, and 35.50%) as well as serum levels of alanine aminotransferase (ALT) and ALT/aspartate aminotransferase (AST) ratio. The serum samples of normal diet (ND) group, HFD group and HFD + EP 450 mg/kg (HFD + MEP) group were further analyzed by ¹ H-NMR spectroscopy. Compared with ND group, 17 and 2 metabolites were significantly upregulated and downregulated in HFD group, respectively. Interestingly, EP treatment significantly downregulated nine metabolites and upregulated one metabolite when compared to those in HFD group. Our results indicated that EP intervention partially ameliorated HFD-induced metabolic dysfunction, and the most prominent metabolic pathways included citrate cycle, synthesis and degradation of ketone bodies, pyruvate metabolism, valine, leucine and isoleucine degradation, and arginine biosynthesis. PRACTICAL APPLICATION: Enteromorpha prolifera polysaccharide (EP), the main active component of Enteromorpha prolifera, is reported to have many biological activities. However, the antiobesity effect of EP and its corresponding metabolic mechanism have not been reported so far. The results of this study confirmed the antiobesity effect of EP on HFD-induced obese hamsters and elucidated its possible metabolic mechanism. Our study highlighted that EP might be used in weight-loss functional foods.

Natural Polyphenols in Metabolic Syndrome: Protective Mechanisms and Clinical Applications

Metabolic syndrome (MetS) is a chronic disease, including abdominal obesity, dyslipidemia, hyperglycemia, and hypertension. It should be noted that the occurrence of MetS is closely related to oxidative stress-induced mitochondrial dysfunction, ectopic fat accumulation, and the impairment of the antioxidant system, which in turn further aggravates the intracellular oxidative imbalance and inflammatory response. As enriched anti-inflammatory and antioxidant components in plants, natural polyphenols exhibit beneficial effects, including improving liver fat accumulation and dyslipidemia, reducing blood pressure. Hence, they are expected to be useful in the prevention and management of MetS. At present, epidemiological studies indicate a negative correlation between polyphenol intake and MetS incidence. In this review, we summarized and discussed the most promising natural polyphenols (including flavonoid and non-flavonoid drugs) in the precaution and treatment of MetS, including their anti-inflammatory and antioxidant properties, as well as their regulatory functions involved in glycolipid homeostasis.