Modulation of methylglyoxal and glutathione by soybean isoflavones in mild streptozotocin-induced diabetic rats

Medicinal plants utilized in Thai Traditional Medicine for diabetes treatment: Ethnobotanical surveys, scientific evidence and phytochemicals

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus remains the most lethal metabolic disease of contemporaneous times and despite the therapeutic arsenal currently available, research on new antidiabetic agents remains a priority. In recent years, the revitalization of Thai Traditional Medicine (TTM) became a clear priority for the Thai government, and many efforts have been undertaken to accelerate research on herbal medicines and their use in medical services in various hospitals. Additionally, and particularly in rural areas, treatment of diabetes and associated symptomatology frequently relies on herbal preparations recommended by practitioners of TTM. In the current work, medicinal plants used in Thailand for treating diabetes, as well as their hypoglycaemic pharmacological evidences and potential therapeutic use for diabetes-related complications were reviewed.

MATERIALS AND METHODS

Ethnopharmacological information on the plant materials used in TTM for diabetes treatment was collected through literature search in a range of scientific databases using the search terms: diabetes, folk medicine, Thailand medicinal plants, traditional medicine. Information regarding scientific evidence on the antidiabetic effects of surveyed species was obtained considering not only the most common taxonomic designation, but also taxonomic synonyms, and including the keywords 'diabetes' and 'hypoglycaemic effect'.

RESULTS

A total of 183 species known to be used for diabetes management in TTM were reviewed, with 30% of them still lacking experimental evidences to support claims regarding the mechanisms and phytochemicals underlying their antidiabetic properties. Moreover, a total of 46 bioactives displaying effective antidiabetic effects have been isolated from 24 species, their underlying mechanism(s) of action being fully or partially disclosed.

CONCLUSIONS

We deliver the most extensive survey dealing with the ethnomedicinal knowledge of Thai medicinal plants utilized on diabetes management. We are certain that the current review will spark further research on Thai plants for the development of new standardized phytomedicines through drug discovery programmes.

Lactobacillus plantarum TWK10-fermented soymilk improves cognitive function in type 2 diabetic rats

BACKGROUND

The brain is especially sensitive to diabetes-induced damage. Chronic hyperglycemia can potentially lead to brain dysfunctions, affecting spatial learning and memory.

RESULTS

The type 2 diabetes (T2D) rats were administered TWK10-fermented soy milk water extract (WE) and ethanol extract (EE) for 6 weeks. WE and EE treatment attenuated T2D-induced alteration in cognitive function assessed using the Morris water maze. Moreover, administration of WE and EE significantly elevated superoxide dismutase activity (166.96% and 181.21%, P < 0.05, respectively) and reduced malondialdehyde concentration (35.03% and 43.97%, P < 0.05, respectively) in the hippocampus of the rats. Additionally, the calmodulin level and nitric oxide concentration were regulated by WE and EE.

CONCLUSION

This study provides scientific evidence that WE and EE enhance anti-oxidative enzyme activity, which subsequently regulates factors associated with cognitive function in T2D rats. © 2020 Society of Chemical Industry.

Effect of soy products and isoflavones on oxidative stress parameters: A systematic review and meta-analysis of randomized controlled trials

Soy products and isoflavones intake have been shown to exert antioxidant effects. There are several randomized control trials (RCTs) that evaluated the effect of soy products intake on oxidative stress (OS) parameters. The aim of the present systematic review and meta-analysis was to summarize the results of RCTs evaluating the effect of soy products and isoflavones intake on OS parameters. Randomized trials that assessed the effect of soy products and isoflavones intake on OS parameters in adults were identified through searching in electronic databases: Cochrane clinical trial center, Embase, PubMed, Scopus, and Web of Sciences up to April 2020. Random effects model was used to calculate the effects sizes of soy intake on OS parameters. Twenty-four trials with 1,852 participants were eligible and were included in the meta-analysis which measured OS parameters. Soy intake compared to control group significantly reduced MDA levels (SMD: -0.53; 95% CI: -0.86, -0.19; I2 = 88.3%), increased GSH levels (SMD: 0.51; 95% CI: 0.13, 0.88; I2 = 72.4%), SOD activity (SMD: 0.53; 95% CI: 0.08, 0.99; I2 = 84.1%), TAC (SMD: 0.54; 95% CI: 0.27, 0.82; I2 = 49.3%) and TRAP (SMD: 1.74; 95% CI: 0.82, 2.65; I2 = 81.3%) significantly compared to control group. Soy products and isoflavones intake are effective in improving OS parameters in adults compared with controls; thus, it could be a valuable advise to control OS progress in chronic diseases.

Incipient Diabetes Treated with Long-Term Classical Prescription

BACKGROUND

Diabetes mellitus (DM) belongs to the progressive and irreversible disease. With the development of the disease, the function of beta cells declines significantly. Current treatments cannot reverse the course of the disease. The role of traditional Chinese medicine (TCM) in the DM treatment has been recognized widely, while there are few long-term observation reports. In this study, we introduced a case of DM treated by classical prescription alone for 10 years, which would provide the reference for clinical practice.

CASE PRESENTATION

A 64-year-old male complained of a 2-month history of dry mouth, frequent urination, and blurred vision and found increased blood glucose for 3 days. The patient's glycated hemoglobin was 14.2%, fasting plasma glucose fluctuated at 12-15 mmol/L, and urinary albumin excretion rate (UAER) was 32.9 μg/min. The male was treated with 10 years of continuous classical prescription alone. After 3 months of TCM treatment, the patient's blood glucose level decreased significantly and blurred vision symptoms improved. With continued TCM treatment, his UAER normalized. Subsequently, he continued outpatient consultation, and his TCM prescription was adjusted according to clinical symptoms. After 10 years of continuous TCM treatment, his blood glucose remained stable, urinary microalbumin quantitation showed no abnormalities, and blurred vision disappeared.

CONCLUSIONS

This case provides specific treatment plans and effective references for long-term control of blood glucose, prevention and treatment of diabetes complications, delay of disease progression, and protection of impaired islet function in the treatment of diabetes with TCM. TCM may become a meaningful alternative DM treatment in the future.

Pharmacological activities of 4-methylene-8-hydroxybisabola-2,10-diene-9-one, a new compound isolated from Ryudai gold (Curcuma longa)

We previously reported the antifungal, antioxidant, and vasodilator effects of Ryudai gold (RD) and isolated some potentially active compounds. Here, we aimed to identify other active compounds present in RD and investigate their pharmacological effects, in terms of antioxidant, and inhibitory activities against skin disease-related enzymes, pancreatic α-amylase, and lipase enzymes. The methanol extract of RD rhizomes was subjected to repeated fractionation by silica gel column, Toyopearl HW-40F column, and high-performance liquid chromatography to obtain a pure compound. The isolated compound was characterized by analyzing its spectroscopic data, particularly nuclear magnetic resonance spectra. Inhibitory activities against α-amylase, pancreatic lipase, elastase, collagenase, xanthine oxidase, and tyrosinase were evaluated to investigate its potential antidiabetic, antiobesity, and enzyme inhibitory effects. Antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl-scavenging, reducing power, and 2-deoxyribose degradation assays. The purified compound was recognized as 4-methylene-8-hydroxybisabola-2,10-diene-9-one, a new compound. The content of this compound was 0.068 μmol/g or 0.016 mg/g of dry RG powder. Our results suggested that 4-methylene-8-hydroxybisabola-2,10-diene-9-one exhibited antidiabetic, antiobesity, enzyme inhibitory, and antioxidant activities by inhibiting their respective enzymes activity. 4-methylene-8-hydroxybisabola-2,10-diene-9-one could be a promising candidate therapeutic agent or a lead compound for the development of new synthetic drugs.

Effectiveness of traditional Chinese medicine Jinlida granules as an add-on therapy for type 2 diabetes: A system review and meta-analysis of randomized controlled trials

BACKGROUND

Jinlida granules are a commonly prescribed oral medication in China used in combination with antidiabetic drugs to lower blood glucose. The aim of this study was to systematically identify and pool the findings of randomized controlled trials evaluating the effectiveness and safety of Jinlida granules as add-on therapy for glycemic control in type 2 diabetes (T2D).

METHODS

The China National Knowledge Infrastructure (CNKI), Wang Fang, PubMed, China biology medicine (CBM), and VIP Database for Chinese Technical Periodicals (VIP) databases were searched for papers regarding the effects of Jinlida granules in T2D published before 1 July 2018. A pooled analysis of extracted data was performed using random-effects models.

RESULTS

In all, data were retrieved for 15 studies including 1810 individuals. Decreases in HbA1c were greater in groups receiving Jinlida granules as add-on therapy compared with control groups (n = 1820; mean difference - 0.66; 95% confidence interval - 0.72, -0.60; P < 0.00001; I²  = 38%). In addition, Jinlida granules reduced body mass index and had beneficial effects on homeostatic model assessment of β-cell function and homeostasis model assessment of insulin resistance. No obvious adverse events were reported.

CONCLUSIONS

Findings from this meta-analysis demonstrate additional benefits of Jinlida granules as an add-on therapy for T2D and that Jinlida granules are generally safe. Treatment with Jinlida granules provided clinically and statistically significant reductions in fasting plasma glucose, 2-hour post-load glucose, and HbA1c levels in patients with T2D. However, the findings should be interpreted with caution due to the small sample size and study limitations.

Does Adjuvant Treatment with Chinese Herbal Medicine to Antidiabetic Agents Have Additional Benefits in Patients with Type 2 Diabetes? A System Review and Meta-Analysis of Randomized Controlled Trials

Introduction

In the present meta-analysis, we aimed to determine the effects of adjuvant treatment with Chinese herbal medicine (CHM) on antidiabetic agents having additional benefits in patients with type 2 diabetes.

Methods

Randomized controlled trials were identified by searching the Cochrane Library, PUBMED, EMBASE, MEDLINE, the China National Knowledge Internet, Web of Science, Global Health, International Pharmaceutical Abstracts and the China biology medicine, Wanfang, and VIP databases. The intervention group received CHM as add-on treatment to antidiabetic agents therapy, and the control group received placebos in addition to antidiabetic agents or antidiabetic agents alone. We assessed pooled data, including weighted mean differences and 95% confidence intervals (CIs) using a random-effects model.

Results

A total of 125 randomized controlled trials were included. 10 articles were included based on literature screening. All trials contrasted Chinese herbal medicines or Chinese herbal medicines + antidiabetic agents with placebo or antidiabetic agents + placebo and included a total of 2004 individuals with T2DM. All selected trials displayed evidence of high methodological quality and possessed a low risk of bias. Meta-analysis of the trials demonstrated that Chinese herbal medicines resulted in a more favorable blood glucose profile in contrast to placebo (P<0.05). The total efficacy rate differed significantly between the two groups (P<0.001). All ten included studies reported the occurrence of tolerable adverse effects.

Conclusions

The results showed that in the intervention group, greater reductions were achieved for glucose control and body weight. The combined use of drugs improves the curative effect and has fewer adverse events and has additional benefits in patients with type 2 diabetes. This trial is registered with PROSPERO (CRD42018093867).

Glibenclamide impairs responses of neutrophils against Burkholderia pseudomallei by reduction of intracellular glutathione

The major risk factor for melioidosis, an infectious disease caused by B. pseudomallei, is diabetes mellitus. More than half of diabetic melioidosis patients in Thailand were prescribed glibenclamide. Recent evidence demonstrates that glibenclamide reduces pro-inflammatory cytokine production by polymorphonuclear neutrophils (PMNs) of diabetic individuals in response to this bacterial infection. However, the mechanisms by which glibenclamide affects cytokine production are unknown. We found that PMNs from glibenclamide-treated diabetic individuals infected with live B. pseudomallei in vitro showed lower free glutathione (GSH) levels compared with those of healthy individuals. Glibenclamide decreased GSH levels and glutathione peroxidase (GPx) of PMNs after exposed to live B. pseudomallei. Moreover, glibenclamide reduced cytokine production and migration capacity of infected PMNs, whereas GSH could restore these functions. Taken together, our data show a link between the effect of glibenclamide on GSH and PMN functions in response to B. pseudomallei that may contribute to the susceptibility of diabetic individuals to B. pseudomallei infection.

Small molecules, both dietary and endogenous, influence the onset of lens cataracts

How the lens ages successfully is a lesson in biological adaption and the emergent properties of its complement of cells and proteins. This living tissue contains some of the oldest proteins in our bodies and yet they remain functional for decades, despite exposure to UV light, to reactive oxygen species and all the other hazards to protein function. This remarkable feat is achieved by a shrewd investment in very stable proteins as lens crystallins, by providing a reservoir of ATP-independent protein chaperones unequalled by any other tissue and by an oxidation-resistant environment. In addition, glutathione, a free radical scavenger, is present in mM concentrations and the plasma membranes contain oxidation-resistant sphingolipids what compromises lens function as it ages? In this review, we examine the role of small molecules in the prevention or causation of cataracts, including those associated with diet, metabolic pathways and drug therapy (steroids).

Methylglyoxal Impairs Insulin Secretion of Pancreatic β-Cells through Increased Production of ROS and Mitochondrial Dysfunction Mediated by Upregulation of UCP2 and MAPKs

Methylglyoxal (MG) is a highly reactive glucose metabolic intermediate and a major precursor of advanced glycation end products. MG level is elevated in hyperglycemic disorders such as diabetes mellitus. Substantial evidence has shown that MG is involved in the pathogenesis of diabetes and diabetic complications. We investigated the impact of MG on insulin secretion by MIN6 and INS-1 cells and the potential mechanisms of this effect. Our study demonstrates that MG impaired insulin secretion by MIN6 or ISN-1 cells in a dose-dependent manner. It increased reactive oxygen species (ROS) production and apoptosis rate in MIN6 or ISN-1 cells and inhibited mitochondrial membrane potential (MMP) and ATP production. Furthermore, the expression of UCP2, JNK, and P38 as well as the phosphorylation JNK and P38 was increased by MG. These effects of MG were attenuated by MG scavenger N-acetyl cysteine. Collectively, these data indicate that MG impairs insulin secretion of pancreatic β-cells through increasing ROS production. High levels of ROS can damage β-cells directly via JNK/P38 upregulation and through activation of UCP2 resulting in reduced MMP and ATP production, leading to β-cell dysfunction and impairment of insulin production.

S-glutathionylation: relevance in diabetes and potential role as a biomarker

Glutathione is considered the main regulator of redox balance in the cellular milieu due to its capacity for detoxifying deleterious molecules. The oxidative stress induced as a result of a variety of stimuli promotes protein oxidation, usually at cysteine residues, leading to changes in their activity. Mild oxidative stress, which may take place in physiological conditions, induces the reversible oxidation of cysteines to sulfenic acid form, while pathological conditions are associated with higher rates of reactive oxygen species production, inducing the irreversible oxidation of cysteines. Among these, neurodegenerative disorders, cardiovascular diseases and diabetes have been proposed to be pathogenetically linked to this state. In diabetes-associated vascular complications, lower levels of glutathione and increased oxidative stress have been reported. S-glutathionylation has been proposed as a posttranslational modification able to protect proteins from over-oxidizing environments. S-glutathionylation has been identified in proteins involved in diabetic models both in vitro and in vivo. In all of them, S-glutathionylation represents a mechanism that regulates the response to diabetic conditions, and has been described to occur in erythrocytes and neutrophils from diabetic patients. However, additional studies are necessary to discern whether this modification represents a biomarker for the early onset of diabetic vascular complications.

The protective effect and underlying mechanism of metformin on neointima formation in fructose-induced insulin resistant rats

Background

Insulin resistance is strongly associated with the development of type 2 diabetes and cardiovascular disease. However, the underlying mechanisms linking insulin resistance and the development of atherosclerosis have not been fully elucidated. Moreover, the protective effect of antihyperglycemic agent, metformin, is not fully understood. This study investigated the protective effects and underlying mechanisms of metformin in balloon-injury induced stenosis in insulin resistant rats.

Methods

After 4 weeks high fructose diet, rats received balloon catheter injury on carotid arteries and were sacrificed at 1 and 4 weeks post injury. Biochemical, histological, and molecular changes were investigated.

Results

Plasma levels of glucose, insulin, total cholesterol, triglyceride, free fatty acids, and methylglyoxal were highly increased in fructose-induced insulin resistant rats and treatment with metformin significantly improved this metabolic profile. The neointimal formation of the carotid arteries was enhanced, and treatment with metformin markedly attenuated neointimal hyperplasia. A significant reduction in BrdU-positive cells in the neointima was observed in the metformin-treated group (P < 0.01). Insulin signaling pathways were inhibited in insulin resistant rats while treatment with metformin enhanced the expression of insulin signaling pathways. Increased expression of JNK and NFKB was suppressed following metformin treatment. Vasoreactivity was impaired while treatment with metformin attenuated phenylephrine-induced vasoconstriction and enhanced methacholine-induced vasorelaxation of the balloon injured carotid arteries in insulin resistant rats.

Conclusion

The balloon-injury induced neointimal formation of the carotid arteries is enhanced by insulin resistance. Treatment with metformin significantly attenuates neointimal hyperplasia through inhibition of smooth muscle cell proliferation, migration, and inflammation as well as by improvement of the insulin signaling pathway.

Specific local cardiovascular changes of Nepsilon-(carboxymethyl)lysine, vascular endothelial growth factor, and Smad2 in the developing embryos coincide with maternal diabetes-induced congenital heart defects

OBJECTIVE

Embryos exposed to a diabetic environment in utero have an increased risk to develop congenital heart malformations. The mechanism behind the teratogenicity of diabetes still remains enigmatic. Detrimental effects of glycation products in diabetic patients have been well documented. We therefore studied a possible link between glycation products and the development of congenital cardiovascular malformations. Furthermore, we investigated other possible mechanisms involved in this pathogenesis: alterations in the levels of vascular endothelial growth factor (VEGF) or phosphorylated Smad2 (the latter can be induced by both glycation products and VEGF).

RESEARCH DESIGN AND METHODS

We examined the temporal spatial patterning of the glycation products Nepsilon(carboxymethyl)lysine (CML) and methylglyoxal (MG) adducts, VEGF expression, and phosphorylated Smad2 during cardiovascular development in embryos from normal and diabetic rats.

RESULTS

Maternal diabetes increased the CML accumulation in the areas susceptible to diabetes-induced congenital heart disease, including the outflow tract of the heart and the aortic arch. No MG adducts could be detected, suggesting that CML is more likely to be indicative for increased oxidative stress than for glycation. An increase of CML in the outflow tract of the heart was accompanied by an increase in phosphorylated Smad2, unrelated to VEGF. VEGF showed a time-specific decrease in the outflow tract of embryos from diabetic dams.

CONCLUSIONS

From our results, we can conclude that maternal diabetes results in transient and localized alterations in CML, VEGF expression, and Smad2 phosphorylation overlapping with those regions of the developing heart that are most sensitive to diabetes-induced congenital heart disease.