Resveratrol, a natural phytoalexin, normalizes hyperglycemia in streptozotocin-nicotinamide induced experimental diabetic rats

Clinical applications and mechanism insights of natural flavonoids against type 2 diabetes mellitus

Diabetes is a complex disease that affects a large percentage of the world's population, and it is associated with several risk factors. Self-management poses a significant challenge, but natural sources have shown great potential in providing effective glucose reducing solutions. Flavonoids, a class of bioactive substances found in different natural sources including medicinal plants, have emerged as promising candidates in this regard. Indeed, several flavonoids, including apigenin, arbutin, catechins, and cyanidin, have demonstrated remarkable anti-diabetic properties. The clinical effectiveness of these flavonoids is linked to their potential to decrease blood glucose concentration and increase insulin concentration. Thus, the regulation of certain metabolic pathways such as glycolysis and neoglycogenesis has also been demonstrated. In vitro and in vivo investigations revealed different mechanisms of action related to flavonoid compounds at subcellular, cellular, and molecular levels. The main actions reside in the activation of glycolytic signaling pathways and the inhibition of signaling that promotes glucose synthesis and storage. In this review, we highlight the clinical efficiency of natural flavonoids as well as the molecular mechanisms underlying this effectiveness.

Revealing metabolic and biochemical variations via 1H NMR metabolomics in streptozotocin-nicotinamide-induced diabetic rats treated with metformin

The increasing prevalence of lean diabetes has prompted the generation of animal models that mimic metabolic disease in humans. This study aimed to determine the optimum streptozotocin-nicotinamide (STZ-NA) dosage ratio to elicit lean diabetic features in a rat model. It also used a proton nuclear magnetic resonance (1H NMR) urinary metabolomics approach to identify the metabolic effect of metformin treatment on this novel rat model. Three different STZ-NA dosage regimens (by body weight: Group A: 110 mg/kg NA and 45 mg/kg STZ; Group B: 180 mg/kg NA and 65 mg/kg STZ and Group C: 120 mg/kg NA and 60 mg/kg STZ) were administered to Sprague-Dawley rats along with oral metformin. Group A diabetic rats (A-DC) showed favorable serum biochemical analyses and a more positive response toward oral metformin administration relative to the other STZ-NA dosage ratio groups. Orthogonal partial least squares-discriminant analysis (OPLS-DA) revealed that glucose, citrate, pyruvate, hippurate, and methylnicotinamide differentiating the OPLS-DA of A-MTF rats (Group A diabetic rats treated with metformin) and A-DC model rats. Subsequent metabolic pathway analyses revealed that metformin treatment was associated with improvement in dysfunctions caused by STZ-NA induction, including carbohydrate metabolism, cofactor metabolism, and vitamin and amino acid metabolism. In conclusion, our results identify the best STZ-NA dosage ratio for a rat model to exhibit lean type 2 diabetic features with optimum sensitivity to metformin treatment. The data presented here could be informative to improve our understanding of non-obese diabetes in humans through the identification of possible activated metabolic pathways in the STZ-NA-induced diabetic rats model.

Attenuation of epithelial-mesenchymal transition via SGLT2 inhibition and diabetic cataract suppression by dapagliflozin nanoparticles treatment

AIMS

Chronic hyperglycemia triggers overproduction of AKR1B1 (aldo-keto reductase family 1 member B) and receptor for advanced glycation end product (RAGE), which causes epithelial-mesenchymal transition (EMT) in the lens epithelial cells (LECs) of diabetic mellitus (DM) cataracts. However, it is unclear whether EMT in LECs is related to abnormal increase of SGLT2. Sodium glucose cotransporter 2 (SGLT2) inhibitor, also known as dapagliflozin (Dapa) can be used to treat diabetes. Here, we examined how Dapa or nano eye-drops (DapaN) reduce EMT in LECs of DM cataracts. The nano eye-drop provides an ophthalmic treatment that suppressed diabetic cataract progression and improved potency with reduced side effects.

MAIN METHODS

SD rats were injected with streptozocin (STZ) (65 mg/kg, ip), nano-Dapa drops (0.456 mg/10 ml/eye) or Dapa (1.2 mg/kg/day) treatment for 6-12 weeks. Immunofluorescence staining was used for protein quantification of RAGE, SGLT2, N-cadherin and E-cadherin in the LECs of rats.

KEY FINDINGS

In this study, Dapa applies nanotechnology-based delivery system and it contains polyvinylpyrrolidone (PVP) and HPBCD. Dapa showed therapeutic effect on DM cataracts, wherein it targeted EMT biomarker, E-cadherin. The nano-Dapa drops or oral Dapa inhibited SGLT2, suppressed AKR1B1 expression, decreased AcSOD2- and RAGE-induced EMT in diabetic cataracts. Our findings suggest that nanotechnology-based Dapa eye drops (Dapa-PVP-HPBCD) can effectively improve solubility of Dapa in aqueous solution.

SIGNIFICANCE

Taken together, results suggest that the SGLT2-mediated DM cataract therapy may involve the AKR1B1-RAGE-AcSOD2-EMT pathway. The nano eye drops and Dapa show potential beneficial effects for cataract prevention. This study conveys new insights into cataract treatment and supplementation of nano-Dapa drops shows promising result in preventing diabetic cataracts.

Composite Hydrogels of Ultrasound-Assisted-Digested Formic Acid-Decellularized Extracellular Matrix and Sacchachitin Nanofibers Incorporated with Platelet-Rich Plasma for Diabetic Wound Treatment

In this study, an ultrasound-assisted digestion method of a formic acid-decellularized extracellular matrix (dECM) of porcine skin was developed and optimized to form UdECM hydrogels for diabetic wound healing. Results demonstrated that ultrasonication improved the extraction rate of collagen from dECM samples, preserved the collagen content of dECM, reduced residual cells, and extracted greater DNA contents. Scanning electron microscope (SEM) analyses were performed, which demonstrated the optimal porosity on the surface and density of the cross-section in the hydrogel structure, which could control the release of growth factors embedded in UdECM hydrogels at desirable rates to boost wound healing. A wound-healing study was conducted with six different composite hydrogels, both empty materials and materials enriched with rat platelet-rich plasma (R-PRP), sacchachitin nanofibers (SCNFs), and TEMPO-oxidized sacchachitin in diabetic rats. The assessment based on scars stained with hematoxylin and eosin (H&E), Masson's trichrome (MT), and a cluster of differentiation 31 (CD31) staining showed that the UdECM/SC/R-PRP treatment group had the most significant efficacy of promoting healing and even recovery of diabetic wounds to normal tissues. UdECM/R-PRP and UdECM/SCNFs demonstrated better healing rates than UdECM hydrogel scaffolds, which had only recovered 50% resemblance to normal skin. Treatment with both UdECM/TEMPO 050 and UdECM/TEMPO 050/R-PRP hydrogel scaffolds was ranked last, with even poorer efficacy than UdECM hydrogels. In summary, formulated UdECM and SCNF hydrogels loaded with PRP showed synergistic effects of accelerating wound healing and ultimately stimulating the wound to recover as functional tissues. This newly UdECM/SCNF composite hydrogel has promising potential for healing and regenerating diabetic wounds.

Evaluation of anti-inflammatory, diuretic and oral glucose tolerance activities of phenolic compound-rich fractions of Hammada articulata in Albino Wistar rats

Hammada articulata is a plant widely used by the locals of the Algerian Sahara for multiple medicinal purposes. However, little was known about its chemical composition and the mechanisms of its bioactivity. For this purpose, the derived extracts [chloroform (CHCl₃), ethyl acetate (EtOAc) and n-butanol (n-BuOH)] of the 80% ethanol extract of its aerial parts, were evaluated for their anti-inflammatory, diuretic, and anti-hyperglycemic activities in vivo. A preliminary phytochemical screening of H. articulata extracts showed the presence of a variety of secondary metabolites. RP-HPLC/DAD was used to analyze some fractions obtained by fractionation of the three derived extracts, by column chromatography and chosen because of the abundance and simplicity of their chemical composition. The fractions obtained from EtOAc and n-BuOH extracts showed a particular richness in phenolic compounds mainly naringenin, quercetin, kaempferol, myricetin, and rutin, which were known for their many interesting biological activities. The three derived extracts from H. articulata were assessed for their anti-inflammatory activity in the carrageenan-induced edema model in rats and their diuretic activity using hydrochlorothiazide (HCTZ) as a diuretic reference. All extracts showed considerable anti-inflammatory activity; the highest was registered in the group treated with the n-BuOH extract. However, for the diuretic activity, only the chloroform extract was active, with a diuretic spectrum similar to that of the standard diuretic HCTZ. The anti-hyperglycemic effect was carried out on the three derived extracts administered orally at a dose of 200 mg/kg, using the glucose tolerance test after gavage with the extracts. The EtOAc and n-BuOH extracts showed significant anti-hyperglycemic activity, improving oral glucose tolerance in normal rats.

The Impact of Resveratrol-Enriched Bread on Cardiac Remodeling in a Preclinical Model of Diabetes

The World Health Organization aims to stop the rise of diabetes by 2025, and diet is one of the most efficient non-pharmacological strategies used to prevent it. Resveratrol (RSV) is a natural compound with anti-diabetic properties, and incorporating it into bread is a suitable way to make it more accessible to consumers as it can be included as part of their daily diet. This study aimed to evaluate the effect of RSV-enriched bread in preventing early type 2 diabetes cardiomyopathy in vivo. Male Sprague Dawley rats (3 weeks old) were divided into four groups: controls with plain bread (CB) and RSV bread (CBR), and diabetics with plain bread (DB) and RSV bread (DBR). Type 2 diabetes was induced by adding fructose to the drinking water for two weeks followed by an injection of streptozotocin (STZ) (40 mg/kg). Then, plain bread and RSV bread (10 mg RSV/kg body weight) were included in the rats' diet for four weeks. Cardiac function, anthropometric, and systemic biochemical parameters were monitored, as well as the histology of the heart and molecular markers of regeneration, metabolism, and oxidative stress. Data showed that an RSV bread diet decreased the polydipsia and body weight loss observed in the early stages of the disease. At the cardiac level, an RSV bread diet diminished fibrosis but did not counteract the dysfunction and metabolic changes seen in fructose-fed STZ-injected rats.

Mung Bean (Vigna radiata (L.) R. Wilczek) from Burkina Faso Used as Antidiabetic, Antioxidant and Antimicrobial Agent

Chronic non-communicable diseases are becoming more and more recurrent and require the addition of functional foods in our eating habits. Legumes due to their composition in biomolecules could meet this need. Much used in Chinese medicine, the mung bean arouses interest in Burkina Faso. The objective of this study is to perform phytochemical profiling and to evaluate certain biological properties of the mung bean in its natural or germinated state. Qualitative phytochemical screening was carried out by precipitation and differential staining tests. The antimicrobial activity was tested on in vitro growth by the agar medium diffusion method. DPPH and FRAP methods were used to assess antioxidant activity. The antidiabetic activity of hydroethanolic extracts was evaluated on rats rendered diabetic by streptozotocin, with metformin as a reference molecule. Phytochemistry has revealed the presence of phenolic compounds and derivatives in the mung bean, whether in its natural state (MBN) or in its germinated state (MBG). Only the MBG exhibits antimicrobial activity on 70% of the strains used. It appears that the MBG has a reducing power of the DPPH radical with an IC₅₀ of 28 mg/mL compared to the same extract of the MBN, which had an IC₅₀ of 32.5 mg/mL with a difference (p < 0.05) between the extracts. MBN extracts at a dose of 300 milligrams per kilogram of body weight (mg/kg.bw) showed a reduction (p < 0.0001) in glycaemia and kept the body weight of the animals constant throughout the treatment. In addition, the MBN regulated the level of total cholesterol, tryglicerides of LDL, ASAT, ALAT, urea and creatine. These results show that the mung bean grown in Burkina Faso is a health food, which, integrated into dietary habits, could contribute to the prevention of chronic diseases.

Resveratrol in Treating Diabetes and Its Cardiovascular Complications: A Review of Its Mechanisms of Action

Diabetes mellitus (DM) is one of the most prevalent chronic diseases worldwide. High morbidity and mortality caused by DM are closely linked to its complications in multiple organs/tissues, including cardiovascular complications, diabetic nephropathy, and diabetic neuropathy. Resveratrol is a plant-derived polyphenolic compound with pleiotropic protective effects, ranging from antioxidant and anti-inflammatory to hypoglycemic effects. Recent studies strongly suggest that the consumption of resveratrol offers protection against diabetes and its cardiovascular complications. The protective effects of resveratrol involve the regulation of multiple signaling pathways, including inhibition of oxidative stress and inflammation, enhancement of insulin sensitivity, induction of autophagy, regulation of lipid metabolism, promotion of GLUT4 expression, and translocation, and activation of SIRT1/AMPK signaling axis. The cardiovascular protective effects of resveratrol have been recently reviewed in the literature, but the role of resveratrol in preventing diabetes mellitus and its cardiovascular complications has not been systematically reviewed. Therefore, in this review, we summarize the pharmacological effects and mechanisms of action of resveratrol based on in vitro and in vivo studies, highlighting the therapeutic potential of resveratrol in the prevention and treatment of diabetes and its cardiovascular complications.

Hypoglycemic, hypolipidemic and hepatoprotective effects of Alpinia officinarum on nicotinamide/streptozotocin induced type II diabetic rats

OBJECTIVES

Alpinia officinarum Hance, commonly known as lesser galangal, is a member of the ginger family (Zingiberaceae) traditionally used for many decades to treat inflammation, pain, stomach ache and cold. In the present study, the antidiabetic and hypolipidemic potentials of the hydroalcoholic extract of A. officinarum (AO) were investigated in the nicotinamide/streptozotocin induced type II diabetic rats.

METHODS

Male Wistar rats were divided into following six groups: Group I was normal control rats. Group II: normal diabetic control, Group III: Diabetic rats treated with glibenclamide (0.25 mg/kg), IV, V and VI: Diabetic rats treated with 100, 200 and 500 mg/kg AO hydroalcoholic extract by daily gavage for 28 days, respectively. At the end of treatment, biochemical analysis, histological study, phytochemical analysis and acute toxicity tests were carried out.

RESULTS

The results show significant reduction in blood glucose, serum lipid profiles, and liver enzyme levels in diabetic rats compared with diabetic control in AO treated group.

CONCLUSIONS

In conclusion, the present study demonstrated that AO extract had significant (p<0.05) antidiabetic and anti-hyperlipidemia effects in addition to hepatoprotective effect in type II diabetic rats.

Resveratrol Alleviates Skeletal Muscle Insulin Resistance by Downregulating Long Noncoding RNA

Long noncoding RNA (lncRNA) is a crucial factor in the progression of insulin resistance (IR). Resveratrol (RSV) exhibits promising therapeutic potential for IR. However, there are few studies on whether RSV improves IR through lncRNA. This study aimed to determine whether RSV could influence the expression of lncRNA and to elucidate the underlying mechanism. Mice were divided into three groups: control group, high-fat diet (HFD) group, and HFD + RSV group. We conducted a high-throughput sequencing analysis to detect lncRNA and mRNA expression signatures and the ceRNA-network in the skeletal muscles of mice that were fed an HFD to induce IR. Hierarchical clustering, gene enrichment, and gene ceRNA-network analyses were subsequently conducted. Differentially expressed lncRNAs were selected and validated via reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The biological functions of the selected lncRNAs were investigated by silencing the target genes via lentivirus transfection of C2C12 mouse myotube cells. RSV treatment reversed the expression of 338 mRNAs and 629 lncRNAs in the skeletal muscles of mice with HFD-induced IR. The results of the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes database analyses indicated that the differentially expressed mRNAs modulated type II diabetes mellitus. After validating randomly selected lncRNAs via RT-qPCR, we identified a novel lncRNA, NONMMUT044897.2, which was upregulated in the HFD group and reversed with RSV treatment. Additionally, NONMMUT044897.2 was proven to function as a ceRNA of microRNA- (miR-) 7051-5p. Suppressor of Cytokine Signaling 1 (SOCS1) was confirmed as a target of miR-7051-5p. We further performed lentivirus transfection to knock down NONMMUT044897.2 in vitro and found that NONMMUT044897.2 silenced SOCS1 and potentiated the insulin signaling pathway. Hence, RSV mimicked the silencing effect of lentivirus transfection on NONMMUT044897.2. Our study revealed that RSV reduced IR in mouse skeletal muscles via the regulation of NONMMUT044897.2.

An Overview on the Therapeutic Function of Foods Enriched with Plant Sterols in Diabetes Management

Diabetes is one of the most significant health issues across the world. People identified with diabetes are more vulnerable to various infections and are at a greater risk of developing cardiovascular diseases. The plant-based food we consume often contains many sterol-based bioactive compounds. It is well documented that these compounds could effectively manage the processes of insulin metabolism and cholesterol regulation. Insulin resistance followed by hyperglycemia often results in oxidative stress level enhancement and increased reactive oxygen species production. At the molecular level, these changes induce apoptosis in pancreatic cells and hence lead to insulin insufficiency. Studies have proved that plant sterols can lower inflammatory and oxidative stress damage connected with DNA repair mechanisms. The effective forms of phyto compounds are polyphenols, terpenoids, and thiols abundant in vegetables, fruits, nuts, and seeds. The available conventional drug-based therapies for the prevention and management of diabetes are time-consuming, costly, and with life-threatening side effects. Thereby, the therapeutic management of diabetes with plant sterols available in our daily diet is highly welcome as there are no side effects. This review intends to offer an overview of the present scenario of the anti-diabetic compounds from food ingredients towards the therapeutic beneficial against diabetes.

The Role of Resveratrol in Liver Disease: A Comprehensive Review from In Vitro to Clinical Trials

Many studies have shown that resveratrol has a lot of therapeutic effects on liver disorders. Its administration can significantly increase the survival rate after liver transplantation, reduce fat deposition and ischemia-induced necrosis and apoptosis in Wistar rats. Resveratrol can provide Liver protection against chemical, cholestatic, and alcohol-mediated damage. It can improve glucose metabolism and lipid profile, reduce liver fibrosis, and steatosis. Additionally, it is capable of altering the fatty acid composition of the liver cells. Resveratrol may be a potential treatment option for the management of non-alcoholic fatty liver disease (NAFLD) due to its anti-inflammatory, antioxidant, and calorie-restricting effects. There are also studies that have evaluated the effect of resveratrol on lipid and liver enzyme profiles among patients with metabolic syndrome (MetS) and related disorders. Based on the extent of liver disease worldwide and the need to find new treatment possibilities, this review critically examines current in vitro and in vivo preclinical studies and human clinical studies related to liver protection.

Resveratrol inhibits macrophage infiltration of pancreatic islets in streptozotocin-induced type 1 diabetic mice via attenuation of the CXCL16/NF-κΒ p65 signaling pathway

AIM

Despite CXC chemokine ligand 16 (CXCL16) contributes to the pathogenesis of many inflammatory disorders, the mechanism by which CXCL16 is involved in T1DM remains unclear. In this study, we examined the role of the CXCL16/NF-κΒ p65 signaling pathway in the progression of this disease and the possible protective effect of resveratrol (RES) on streptozotocin (STZ)-induced T1DM.

MAIN METHODS

Mice were classified into four groups of 10 animals each. The control group received citrate buffer. The RES group received 50 mg/kg i.p. RES for 12 days beginning on day 4 of citrate buffer. The STZ group received 55 mg/kg i.p. STZ once a day for 5 consecutive days. The fourth group injected with RES (50 mg/kg) for 12 days starting on day 4 of STZ injection. Biochemical, physical and oxidative stress parameters were measured in all groups. Moreover, expression of CXCL16 and CD45 was measured in pancreatic islets and spleen. Additionally, NF-κΒ p65 was investigated in isolated islets.

KEY FINDINGS

Our results showed a significant elevation of CXCL16, NF-κΒ p65 and CD45 in islets of diabetic (DM) mice. Intriguingly, RES significantly restored distorted biochemical, physical and oxidative stress parameters after STZ treatment as well as inhibited the expression of CXCL16/NF-κΒ p65 in pancreatic islets. Moreover, RES normalized CXCL16 and CD45 expression in islets and spleen.

SIGNIFICANCE

This study demonstrates first evidence that CXCL16/NF-κΒ p65 signaling pathway is associated with macrophage infiltration to pancreatic islet in T1DM and that RES successfully improved T1DM may be at least via inhibiting this pathway.

Promising anitidiabetic potential of Cuscuta reflexa leaves methanol extract in alloxan-induced diabetic rats

Context

Cuscuta reflexa (C. reflexa) Roxb. (Convolvulaceae) has medicinal properties for the effective management of several aliments including diabetes mellitus, inflammation, and gastric ulcer.

Objective

The present investigation focuses on the antidiabetic potential of C. reflexa leaves methanol extract in alloxan-induced diabetic rats.

Materials and methods

The antidiabetic activity of C. reflexa leaves methanol extract (CRME) was evaluated using alloxan-induced diabetes in Wistar albino rats. The duration of the study was 45 days. Diabetic model was developed by i.p. administration of alloxan monohydrate (120 mg/kg). Ingestion of CRME (100, 200, and 400 mg/kg/day) and standard (gliclazide, 10 mg/kg/day) was done via oral route from the day of diabetes induction and continued up to 45 days. The effect of CRME was investigated by evaluating the blood glucose concentrations, HbA1C, insulin, lipid profile and liver function test. Further, the protective potentials of CRME were studied by histopathology of the pancreas, liver, and kidney tissues from experimental rats.

Results

CRME showed significant (p < 0.01 at all doses) reduction of blood glucose level (137.1 ± 5.8, 125.9 ± 6.5, and 109.5 ± 5.4 mg/dL at the doses of 100, 200, and 400 mg/kg, respectively) as compared to the diabetic control (249.7 ± 7.3 mg/dL). Moreover, CRME at the highest dose decreased HbA1C and improved insulin levels (3.96% and 11 ng/ml, respectively) when compared with diabetic control group (7.55% and 6.5 ng/ml, respectively). CRME also revealed pronounced improvement in liver function test and lipid profile test when compared to the diabetic control. Furthermore, CRME notably reversed the histopathological changes that observed in alloxan-induced diabetes.

Conclusion

Our research exertion clearly demonstrates that CRME can be explored as a substantial antidiabetic and organ protective agent in the management of diabetes.

Antidiabetic activity of corn steep liquor extract of Curculigo pilosa and its solvent fractions in streptozotocin-induced diabetic rats

The rhizome of Curculigo pilosa (CP) prepared with Corn steep liquor (CSL), is traditionally used in the treatment of diabetes mellitus. In this study, antidiabetic activity of the CSL extract and its fractions (butanol and methanol) were evaluated in streptozotocin-induced diabetic rats. Diabetes mellitus was induced by single intraperitoneal administration of streptozotocin (50 mg/kg) and diabetic rats were treated with 300 mg/kg bodyweight of the extract(s) for 28 days. Antidiabetic effect was monitored by plasma blood glucose, oral glucose tolerances test (OGGT), body weight and heamatological indices. Also serum urea, creatinine, cholesterol, high density lipoprotein, bilirubin, alkaline phosphatase, aspartate and alanine transaminases were evaluated. The levels of hepatic glutathione, catalase, superoxide dismutase, lipid peroxidation, nitric oxide and hydrogen peroxide were assessed; also histopathology of the hepatic tissues was examined. Oral administration of the extract resulted in significant (p < 0.05) reduction of plasma blood glucose (29.32% crude extract and 22.96% butanol fraction) and also increased body weight (20.61% crude extract, 13.44% butanol fraction and 6.23% methanol fraction) of diabetic rats. The heamotogical indices, plasma parameters and hepatic oxidative stress in diabetic rats were returned to near normalcy following treatment with the extract(s). The GC-MS analysis of the extract revealed the presence of stilbene, a proven antidiabetic agent, which might be responsible for the antidiabetic activity. The results obtained suggest that the CSL extract of CP could be used in management of diabetes mellitus thus providing scientific validation of its use as an antidiabetic agent.

Delonix regia a Folklore Remedy for Diabetes; Attenuates Oxidative Stress and Modulates Type II Diabetes Mellitus

BACKGROUND

The folkloric profile of Delonix regia demonstrates that it can be used in the management of diabetes.

OBJECTIVE

The present study was conducted to evaluate the safety profile of the aerial part extracts of Delonix regia and their antidiabetic potential along with improvement in oxidative stress.

MATERIALS AND METHODS

Phytochemical screening, total phenolic, and flavonoid contents along with in-vitro antioxidant and alpha-amylase inhibitory activities were determined. HPLC analysis, acute toxicity, glucose tolerance, in-vivo antidiabetic effect along with the influence on biochemical, oxidative stress parameters, and comet assay of the active extract were performed and assessed.

RESULTS

Total phenolic (831.6±0.002 mg/g GAE) and flavonoid (361.4±0.002 mg/g QE) contents were found to be higher in the methanolic extract. Inhibitory concentration IC50 indicated better results for the methanolic extract in DPPH (47.6μg/mL) and alpha-amylase inhibitory (14.61μg/mL) assays. HPLC analysis of the methanolic extract confirmed the presence of quercetin, gallic acid, caffeic acid, cinnamic acid, ferulic acid, and p-coumaric acid. Acute oral toxicity exhibited no mortality and morbidity during the 24h period. The methanolic extract showed better tolerance to glucose. Streptozotocin- nicotinamide (55-110 mg/kg) induced hyperglycemia declined along with improvement in hematological, biochemical parameters and oxidative stress markers (SOD, CAT, H202) in a dose-dependent manner. The maximum effect was recorded at 500mg/kg dose. Comet assay was performed for genotoxic studies and it was observed that the methanolic extract of Delonix regia showed the maximum genoprotective effect at 100μg/mL.

CONCLUSION

The findings suggest that the methanolic aerial part extract of Delonix regia exhibited hypoglycemic, antioxidant, and hypolipidemic activities. The antidiabetic effect was comparable to glibenclamide suggesting its therapeutic use as a natural anti-diabetic remedy.

Evaluation of antidiabetic effect of Cistus salviifolius L. (Cistaceae) in streptozotocin-nicotinamide induced diabetic mice

Objectives Cistus salviifoluis L. is a shrub from Cistaceae family used in many traditional medicines for the treatment of various diseases including diabetes mellitus. The aim of this study was to evaluate the in vivo antidiabetic potential of the aerial parts aqueous extract of Cistus salviifolius L. (CSA). Methods Experimental diabetes was induced in adult male mice by intra-peritoneal injection of Streptozotocin-nicotinamide (STZ-NC). CSA at a dose of 500 mg/kg was administered daily to the diabetic mice for four weeks. The effect of the extract on hyperglycemia, body weight, serum total cholesterol, triglycerides, hepatic and renal functional markers were determined. Histopathological examination of the mice pancreas was also performed. The diabetic animals treated with CSA were compared with animals treated by the standard drug metformin. Results Treatment with CSA showed a significant reduction in blood glucose, total triglycerides and creatinine levels and prevented the reduction of body weight caused by diabetes. Furthermore, histopathological analysis of the mice pancreas showed that the group treated with CSA reduced damage induced by STZ-NC on islets of Langerhans cells when compared to the diabetic control. Conclusions The results suggest that the aqueous extract of Moroccan C. salviifolius L. possesses beneficial effect on treatment of diabetes.

Evaluation of efficacy of Bombax ceiba extract and its major constituent, mangiferin in streptozotocin (STZ)-induced diabetic rats

OBJECTIVES

Based on the ethno-medicinal use of Bombax ceiba leaf, in the treatment of diabetes, the present study is aimed at evaluation of antidiabetic potential of leaf extract and its major constituent mangiferin.

METHODS

Efficacy of hydroalcoholic extract of Bombax ceiba leaf (BCL, 200 and 400 mg/kg body wt.) and mangiferin (MF, 20 mg/kg body wt) was studied in streptozotocin (STZ)-induced diabetic rats and associated complications visually, retinopathy, cardiopathy and nephropathy. After 20 days, serum glucose, lipid profiles, glycol-hemoglobin % (HbA1c%), liver enzymes activity and glycogen content, and histopathology of the pancreas were corroborated. The study was coxswained for development of validated RP-HPLC method for the estimation of MF in BCL.

RESULTS

The results demonstrated significant reductions in the levels of glucose (p<0.001), glycated hemoglobin (HbA1c%, p<0.001), cholesterol, triglycerides and low-density lipoproteins, and concurrent elevation of high density lipoproteins level in the groups administered BCL and MF relative to the controls. It significantly reversed most of the altered metabolic and oxidative stress parameters and histopathological changes. Mangiferin content in BCL was found to be 0.04%w/w.

CONCLUSIONS

The anti-diabetic effects of BCL may be attributed to its ability to enhance insulin release, antioxidant and hypolipidemic potential.

SIRT1-dependent effects of resveratrol and grape juice in an in vitro model of preeclampsia

Preeclampsia (PE) is a multifactorial hypertensive disorder of pregnancy that is partly responsible for both maternal and fetal morbidity and mortality levels worldwide. It has been recently discovered that sirtuin-1 (SIRT1) is reduced in the circulation and in an in vitro model of PE. Therefore, in this study, we investigated the effects of trans-resveratrol, a potent antioxidant and activator of SIRT1, on oxidative stress and nitric oxide (NO) production in an in vitro model of PE compared to gestational hypertensive (GH) and healthy pregnant (HP) women. Furthermore, we also evaluated the effects of an acute intake of grape juice on women with PE to assess whether it could mimic in vitro trans-resveratrol supplementation. (1) In the GH group, resveratrol decreased intracellular reactive oxygen species (ROS) and increased their antioxidant capacity, while inhibiting SIRT1 reestablished previous levels. (2) In PE, inhibition of SIRT1 increased antioxidant activity. (3) Intracellular NO and supernatant nitrite levels were increased by inhibiting SIRT1 in the PE group. (4) Grape juice intake increased intracellular NO levels versus before grape juice intake control; however, the inhibition of SIRT1 before grape juice intake initially increased NO, but decreased it 1 h after grape juice intake. In conclusion, activating SIRT1 by using resveratrol alone may not be beneficial to women with PE, and GH and PE seem to have different responsive mechanisms to this molecule. Furthermore, grape juice intake seems to have different effects compared to resveratrol supplementation alone in this in vitro model of PE, demonstrating the potential of the combination of other biologically active molecules from grape juice over the SIRT1-eNOS-NO in PE treatment.

Antidiabetic Potency, Antioxidant Effects, and Mode of Actions of Citrus reticulata Fruit Peel Hydroethanolic Extract, Hesperidin, and Quercetin in Nicotinamide/Streptozotocin-Induced Wistar Diabetic Rats

This study is aimed at assessing the antihyperglycemic, antihyperlipidemic, and antioxidant effects of Citrus reticulata (C. reticulata) fruit peel hydroethanolic extract and two flavonoids, hesperidin and quercetin, in nicotinamide (NA)/streptozotocin- (STZ-) induced type 2 diabetic rats. In addition, GC-MS and HPLC-MS analyses of the extract were performed and the results indicated the presence of multiple flavonoids including hesperidin, quercetin, naringin, and polymethoxylated flavones (nobiletin and tangeretin). To achieve the aim of the study, diabetic rats with NA/STZ-induced T2DM were orally treated with C. reticulata fruit peel hydroethanolic extract, hesperidin, and quercetin at a dose of 100 mg/kg b.w./day for four weeks. The treatments with C. reticulata fruit peel extract, hesperidin, and quercetin significantly ameliorated the impaired oral glucose tolerance; the elevated serum fructosamine level; the diminished serum insulin and C-peptide levels; the altered HOMA-IR, HOMA-IS, and HOMA-β cell function; the decreased liver glycogen content; the increased liver glucose-6-phosphatase and glycogen phosphorylase activities; the deleteriously affected serum lipid profile; the elevated serum AST and ALT activities; and the raised serum creatinine and urea levels in the diabetic rats. The treatments also produced remarkable improvement in the antioxidant defense system manifested by a decrease in the elevated liver lipid peroxidation and an increase in the lowered glutathione content and GPx, GST, and SOD activities. Furthermore, the three treatments enhanced the mRNA expression of GLUT-4 and the insulin receptor β-subunit, but only quercetin produced a significant increase in the expression of adiponectin in adipose tissue of diabetic rats. In conclusion, C. reticulata fruit peel hydroethanolic extract, hesperidin, and quercetin have potent antidiabetic effects which may be mediated through their insulinotropic effects and insulin-sensitizing actions. In addition, the alleviation of the antioxidant defense system by the extract, hesperidin, and naringin may have an important action to enhance the antidiabetic actions and to improve liver and kidney functions in NA/STZ-induced diabetic rats.

The effects of synthetic orally administrated insulin nanoparticles in comparison to injectable insulin on the renal function markers of type 1- diabetic rats

OBJECTIVES

Injectable insulin is the most widely used therapy in patients with type 1 diabetes which has several disadvantages. The present study was aimed to evaluate the efficacy of injectable insulin on diabetes mellitus-related complications in comparison to orally encapsulated insulin nanoparticles.

MATERIALS AND METHODS

This study involved 42 Wistar rats separated into 5 groups, including control (C), diabetic control (D), diabetic receiving regular insulin (INS), diabetic receiving encapsulated insulin nanoparticle (INP), and diabetic receiving chitosan for two months. Biochemical parameters in serum and urine were measured using spectrophotometric or ELISA methods. mRNA levels of kidney injury molecule 1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated using quantitative PCR.

RESULTS

There were no significant differences between the two forms of insulin in controlling the glycemic condition (P-value>0.05), but oral INP was more effective in correcting diabetic dyslipidemia in comparison to injectable insulin (P-value<0.05). Urine volume and creatinine excretion were significantly modulated by insulin and oral INP in diabetic groups (P-value<0.05), although the effects of INP on the modulation of execration of urea, acid uric, and albumin was more dramatic. Oral INP caused a significant decrease in urine concentration of KIM-1 and NGAL as well as expression of KIM-1 in renal tissue (P-value<0.05).

CONCLUSION

Our results suggested that oral INP is more effective than injectable insulin in modulation of urine and serum diabetic-related parameters.

Resveratrol reduces oxidative damage and inflammation in mice infected with Trichinella spiralis

Trichinellosis is a serious food-borne zoonotic infection of cosmopolitan distribution. Currently, treatment for trichinellosis is far from ideal. Given the important role of oxidative stress and immune-mediated inflammation in the pathogenesis of trichinellosis, this study was designed to evaluate the possible protective effects of resveratrol (RSV) during the intestinal and muscular phases of Trichinella spiralis infection in mice. The oral administration of RSV at a dose of 20 mg/kg once daily for two weeks resulted in significant reductions in both adult and larval counts; significant improvements in the redox status of the small intestine and muscles; a significant reduction in interleukin 4, pentraxin 3 and vascular endothelial growth factor expression; and the mitigation of intestinal and muscular inflammation. In conclusion, this study identifies RSV as a promising agent for the treatment of experimental trichinellosis, and more studies in experimental animals and humans are worth consideration.

Enhanced oral bioavailability and anti-diabetic activity of canagliflozin through a spray dried lipid based oral delivery: a novel paradigm

AIM

Canagliflozin (CFZ), a novel SGLT II antagonist, exhibits erratic absorption after oral administration. The current study entails development and evaluation of spray dried lipid based formulation (solid SMEDDS) for enhancing oral bioavailability and anti-diabetic activity of CFZ.

METHODS

Solid SMEDDS developed through spray drying containing Neusilin US2 as an adsorbent. The formed solid SMEDDS were characterized for physicochemical and solid state attributes. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to confirm the spherical morphology. In vitro dissolution, ex vivo permeability and in vivo pharmacokinetic studies were conducted to determine the release rate, permeation rate and absorption profile of CFZ, respectively. Pharmacodynamic studies were done as per standard protocols.

RESULTS

The optimized solid SMEDDS exhibited acceptable practical yield and flow properties and is vouched with enhanced amorphization, nanoparticulate distribution and acceptable drug content. The spherical morphology of solid SMEDDS and reconstituted SMEDDS were confirmed in SEM and TEM, respectively. In vitro dissolution studies revealed multi-fold release behavior in CFZ in various dissolution media, whereas, remarkable permeability was observed in jejunum segment of rat intestine. Pharmacokinetic studies of CFZ in solid SMEDDS demonstrated 2.53 and 1.43 fold enhancement in C_max and 2.73 and 1.98 fold in AUC _0-24h, as compared to pure API and marketed formulation, respectively. Pharmacological evaluation of solid SMEDDS revealed enhanced anti-diabetic activity of CFZ through predominant SGLT II inhibition in rats, as evident from evaluation of biochemical levels, urinary glucose excretion studies and SGLT II expression analysis.

CONCLUSION

The current work describes significant improvement biopharmaceutical properties of CFZ in solid SMEDD formulation. Graphical abstract Graphical Abstract: Enhanced oral bioavailability and anti-diabetic activity of canagliflozin through a spray dried lipid based oral delivery: a novel paradigm.

Resveratrol attenuates intestinal injury in irradiated rats via PI3K/Akt/mTOR signaling pathway

Radiation-induced enteritis is one of the greatest challenges in radiotherapy. The current study was designed to evaluate the ameliorative effect of resveratrol, which exhibits anti-inflammatory property, against radiation-induced intestinal injury in rats and to explore the underlying mechanism. Rats were exposed to a single dose of 5 Gy. Resveratrol (20 mg/kg/day) was orally administered to irradiated rats over 3 weeks. Results showed that resveratrol ameliorated the intestinal oxidative stress parameters; malondialdehyde (MDA) content, glutathione (GSH) level, and catalase (CAT) activity compared to irradiated group. Furthermore, resveratrol reduced the contents of inflammatory cytokines; tumor necrosis factor α (TNF-α), nuclear factor-kappa (NF-κB), and interleukin 1β (IL-1β) in intestine. Western blotting analysis revealed that resveratrol down-regulated the proteins expression of phosphoinositide 3-kinases (PI3K), protein kinase B (Akt) as well as the mammalian target of rapamycin (mTOR) in intestinal tissues of irradiated rats and thus reduced the inflammatory mediator production. These results were confirmed by histopathological investigation. In conclusion, resveratrol attenuated intestinal inflammation following irradiation via modulating PI3K/Akt/mTOR pathway and thereby could be a promising adjuvant in radiotherapy.

Investigation of the Effects of a Dietary Supplement on Insulin and Adipokine Concentrations in Equine Metabolic Syndrome/Insulin Dysregulation

High insulin concentrations are a common clinical feature of equine metabolic syndrome (EMS) and insulin dysregulation. Hyperinsulinemia can induce laminitis, so reduction of insulin concentrations in response to an oral challenge should decrease risk. In human studies, diets containing a polyphenol (resveratrol) led to improvements in insulin sensitivity. In rodents, the addition of leucine to a resveratrol supplement caused a decrease in the amount of resveratrol needed to achieve a clinical effect. We hypothesize a supplementation with a low dose of a synergistic polyphenol and amino acid blend including leucine (SPB+L) would improve metabolic health in EMS/insulin dysregulated horses. Fifteen EMS/ID horses received a high or low dose of SPB+ L daily for 6 weeks. Insulin during an oral sugar test (OST), body condition score, weight, baseline high-molecular-weight (HMW) adiponectin, triglycerides, nonesterified fatty acids, and tumor necrosis factor alpha were assessed before supplementation (PRE) and after supplementation (POST) via paired Student's t-tests and a repeated-measures mixed-model analysis of variance (significant at P < .05). There were no differences between doses. Horses in the POST group weighed significantly less, had significantly higher baseline HMW adiponectin concentrations, and had significantly lower insulin concentrations at 60- and 75-minute time points (P < .05). Insulin concentrations of the horsesin the POST group, but not in the PRE group, were lower and similar to results from the study conducted three years before the present study (PRIOR) for 0- and 60-minute time points (P < .002). An increased HMW adiponectin level supports increasing insulin sensitivity after supplementation. These results suggest that SPB + L supplementation at either dose leads to improvements in the clinical manifestations of EMS/insulin dysregulation, potentially reducing laminitis risk.

Resveratrol for adults with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a chronic disorder that is characterised by insulin resistance and hyperglycaemia, which over time may give rise to vascular complications. Resveratrol is a plant-derived nutritional supplement shown to have anti-diabetic properties in many animal models. Less evidence is available on its safety and efficacy in the management of T2DM in humans.

OBJECTIVES

To assess the efficacy and safety of resveratrol formulations for adults with type 2 diabetes mellitus.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), and International Pharmaceutical Abstracts, as well as the International Clinical Trials Registry Platform (ICTRP) Search Portal and ClinicalTrials.gov. The date of the last search was December 2018 for all databases. No language restrictions were applied.

SELECTION CRITERIA

All randomised controlled trials (RCTs) comparing effects of oral resveratrol (any dose or formulation, duration, or frequency of administration) with placebo, no treatment, other anti-diabetic medications, or diet or exercise, in adults with a diagnosis of T2DM.

DATA COLLECTION AND ANALYSIS

Two review authors independently identified and included RCTs, assessed risk of bias, and extracted study-level data. Study authors were contacted for any missing information or for clarification of reported data. We assessed studies for certainty of the evidence using the GRADE instrument.

MAIN RESULTS

We identified three RCTs with a total of 50 participants. Oral resveratrol not combined with other plant polyphenols was administered at 10 mg, 150 mg, or 1000 mg daily for a period ranging from four weeks to five weeks. The comparator intervention was placebo. Overall, all three included studies had low risk of bias. None of the three included studies reported long-term, patient-relevant outcomes such as all-cause mortality, diabetes-related complications, diabetes-related mortality, health-related quality of life, or socioeconomic effects. All three included studies reported that no adverse events were observed, indicating that no deaths occurred (very low-quality evidence for adverse events, all-cause mortality, and diabetes-related mortality). Resveratrol versus placebo showed neutral effects for glycosylated haemoglobin A1c (HbA1c) levels (mean difference (MD) 0.1%, 95% confidence interval (CI) -0.02 to 0.2; P = 0.09; 2 studies; 31 participants; very low-certainty evidence). Due to the short follow-up period, HbA1c results have to be interpreted cautiously. Similarly, resveratrol versus placebo showed neutral effects for fasting blood glucose levels (MD 2 mg/dL, 95% CI -2 to 7; P = 0.29; 2 studies; 31 participants), and resveratrol versus placebo showed neutral effects for insulin resistance (MD -0.35, 95% CI -0.99 to 0.28; P = 0.27; 2 studies; 36 participants). We found eight ongoing RCTs with approximately 800 participants and two studies awaiting assessment, which, when published, could contribute to the findings of this review.

AUTHORS' CONCLUSIONS

Currently, research is insufficient for review authors to evaluate the safety and efficacy of resveratrol supplementation for treatment of adults with T2DM. The limited available research does not provide sufficient evidence to support any effect, beneficial or adverse, of four to five weeks of 10 mg to 1000 mg of resveratrol in adults with T2DM. Adequately powered RCTs reporting patient-relevant outcomes with long-term follow-up periods are needed to further evaluate the efficacy and safety of resveratrol supplementation in the treatment of T2DM.

Efficacy and Safety of Resveratrol in Type 1 Diabetes Patients: A Two-Month Preliminary Exploratory Trial

Resveratrol has been reported to be beneficial against diabetes complications. The objective of this study was to evaluate the efficacy of resveratrol in decreasing hyperglycemia in patients with type 1 diabetes (T1D) by a preliminary investigation designed as an exploratory clinical trial. Thirteen patients with T1D from both the sexes participated in this trial. All patients received resveratrol in 500 mg capsules, twice daily for 60 days. Bodyweight, fasting blood sugar (FBS), hemoglobin A1c (HbA1c), insulin, homeostasis model of assessment for insulin resistance (HOMA-IR), homeostasis model of assessment for β-cell function (HOMA-β), and markers of liver and kidney damage, inflammation, and oxidative stress were measured before the intervention, at 30 days and at 60 days. Resveratrol supplementation for 60 days significantly decreased FBS and HbA1c in comparison with the baseline values. Resveratrol treatment also resulted in a decrease in the level of a marker for oxidative stress, malondialdehyde, and an increase in total antioxidant capacity in T1D patients. Insulin, HOMA-IR, HOMA-β, and markers of liver and kidney function and inflammation were not significantly affected by resveratrol treatment. Overall, the results showed that 60 days of resveratrol supplementation exerted strong antidiabetic and antioxidant effects in patients with T1D.

Resveratrol bidirectionally regulates insulin effects in skeletal muscle through alternation of intracellular redox homeostasis

AIMS

Reactive oxygen species (ROS) bidirectionally regulate insulin sensitivity in skeletal muscle. Insulin-induced ROS generation elevates insulin-regulated metabolic effects; however, chronic oxidative stress causes severe insulin resistance in skeletal muscle. Resveratrol (RV), as a natural antioxidant, eliminates intracellular ROS. It's unclear that whether it has different roles in insulin signaling pathway in skeletal muscle.

MAIN METHODS

C57BL/6J mice and C2C12 myotubes were used to assess metabolic regulation effects of RV. Protein activation was detected using Immunofluorescence and Western Blot analysis. ROS were analyzed using confocal microscope and flow cytometry sorting (FACS). Intracellular reducing molecules were detected using an enzymatic method. Glucose uptake was measured using a fluorescent deoxyglucose analog (2-NBDG).

KEY FINDINGS

We found that RV attenuated insulin-stimulated AKT phosphorylation via elimination of insulin-induced ROS generation in skeletal muscle, suggesting that RV decreased activation of the insulin-induced AKT signaling. In skeletal muscle of insulin resistance, RV reduced oxidative stress, restored intracellular glutathione (GSH) level, and enhanced insulin-induced AKT activation and glucose absorption. These results suggested that RV ameliorated insulin resistance by change of redox levels in skeletal muscle.

SIGNIFICANCE

This study revealed bidirectional regulation effects of RV on insulin-stimulated metabolism in skeletal muscle through alternation of intracellular redox homeostasis, which might provide a guidance role for treatment of metabolic diseases.

Hypoglycaemic effect of resveratrol in streptozotocin-induced diabetic rats is impaired when supplemented in association with leucine

Studies have shown synergistic and independent effects of leucine and resveratrol (RSV) as possible therapeutic agents to ameliorate metabolic disorders. Thus, the objective of this study was to investigate the effects of supplementation with leucine and RSV, alone and in combination, on metabolic changes in white adipose tissue of neonatally STZ-induced diabetic rats. After weaning, the rats were treated with trans-resveratrol (0.6 mg/kg/dose) and/or leucine (1.35 mg/kg/dose) administered orally. The animals were euthanized at age 16 weeks for blood analyses. Subcutaneous (SC), periepididymal (PE) and retroperitoneal (RP) fat pads were weighed. Adipocytes from PE and RP pads were isolated for morphometric analysis. Long-term supplementation with RSV promoted adiposity recovery, prevented hypoinsulinemia and improved the metabolic profile of the diabetic rats. However, some of these effects were impaired when RSV was associated with leucine. The diabetic rats supplemented with leucine alone showed no significant improvement in metabolic disorders.

Glut 1 in Cancer Cells and the Inhibitory Action of Resveratrol as A Potential Therapeutic Strategy

An important hallmark in cancer cells is the increase in glucose uptake. GLUT1 is an important target in cancer treatment because cancer cells upregulate GLUT1, a membrane protein that facilitates the basal uptake of glucose in most cell types, to ensure the flux of sugar into metabolic pathways. The dysregulation of GLUT1 is associated with numerous disorders, including cancer and metabolic diseases. There are natural products emerging as a source for inhibitors of glucose uptake, and resveratrol is a molecule of natural origin with many properties that acts as antioxidant and antiproliferative in malignant cells. In the present review, we discuss how GLUT1 is involved in the general scheme of cancer cell metabolism, the mechanism of glucose transport, and the importance of GLUT1 structure to understand the inhibition process. Then, we review the current state-of-the-art of resveratrol and other natural products as GLUT1 inhibitors, focusing on those directed at treating different types of cancer. Targeting GLUT1 activity is a promising strategy for the development of drugs aimed at treating neoplastic growth.

Concomitant administration of resveratrol and insulin protects against diabetes mellitus type-1-induced renal damage and impaired function via an antioxidant-mediated mechanism and up-regulation of Na+/K+-ATPase

This study investigated if a combination of resveratrol (RES) and insulin could reverse type 1 diabetic mellitus-induced (T1DM) nephropathy and illustrates mechanism of action. Rats were divided into six groups (n = 10/group) as follows: control, control + RES (20 mg/kg), T1DM, T1DM + RES, T1DM + insulin (1 U/g), and T1DM + RES + insulin and treated for eight weeks. While individual administrations of both drugs significantly but partially restored renal function and cortex architectures, combination therapy of both RES and insulin produced the maximum improvements. Mechanism of actions revealed a synergist effect of both drugs due to hypoglycaemic effect of insulin and the ability of both drugs to increase renal cortex antioxidant enzymes activities, inhibit lipid peroxidation, and up-regulate Na⁺/K⁺-ATPase, independent of each others. In conclusion, these data suggest the combined therapy with insulin and RES could provide an excellent combined drug therapy against T1DM-induced nephropathy.

The antidiabetic and antioxidant properties of some phenolic phytochemicals: A review study

BACKGROUND

One class of phytochemicals are phenols with (OH) group bounded to aromatic hydrocarbon group. The aim of this study was to review the anti-diabetic and anti-oxidant properties of important phenols.

METHODS

This is a review study with ethic number (95s108) from AJUMS. About 450 articles (original, review,etc) been screened; 40 of them in the range of (1992-2017) were used due to their correlation to the study purpose. 28 of them were indexed by "Web of science (ISI)", 24 of them indexed by pubmed and also 29 of them were indexed by scopus data center.

FINDINGS

Phenols affect diabetes in different ways. CGA suppress hepatic gluconeogenesis through the inhibition of G6Pase and is also an insulin sensitizer that potentiates insulin action. Curcumin reduce insulin resistance so decrease AGE's products in diabetes mellitus. Hydroxytyrosol regulates the calcium channels which plays key role in insulin secretion. Resveratrol increase the stimulation of glucose uptake and insulin secretion. CGA has similar antioxidant activity as vitamin E and ellagic acid maybe is even more potent than vitamin E. curcumin inhibits lipid peroxidation and scavenge superoxide anion and hydroxyl radicals. The antioxidant activity of hydroxytyrosol protects pancreatic cells from damage and death. Treatment with resveratrol significantly decreases the level of glucosylated hemoglobin.

CONCLUSION

All these phytochemicals have potent antidiabetic and antioxidant effects in different ways beside their other effects like anti-inflammatory and anti-carcinogenic properties in ellagic acid, or like anti-angiogenic and apoptogenic activities in curcumin. So we suggest further studies in the field of diabetes and antioxidation.

Effects of Resveratrol on FOXO1 and FOXO3a Genes Expression in Adipose Tissue, Serum Insulin, Insulin Resistance and Serum SOD Activity in Type 2 Diabetic Rats

Induced oxidative stress in diabetes mellitus (DM) plays a critical role in insulin resistance. Fork head-related transcription factor (FOXO) proteins are important transcriptional factors involved in oxidative stress and insulin resistance. Resveratrol (RSV) is a polyphenol with hypoglycemic and antioxidant properties. The aims of the present study were to examine the effects of RSV on FOXO gene expression, serum superoxide dismutase (SOD) activity, insulin level, and insulin resistance in type 2 diabetic (T2DM) rats. Thirty male Wistar rats were used in this study. DM was induced in rats (n=24) using streptozotocin (STZ) and nicotinamide; then, they were divided into 4 groups of 6 rats each. Six untreated normal rats were used as normal control group; diabetic rats in groups 2 to 5 were treated with 0, 1, 5 and 10 mg /kg body weight of RSV, respectively for 30 days. At the end of the experimental period, the rats were sacrificed, their sera were separated, and adipose tissues were obtained and stored at −80 °C. Serum glucose and SOD activity levels were determined biochemically, and serum insulin level was determined by ELISA method. Gere expression in FOXO1 and FOXO3a in adipose tissue was evaluated using real‐time PCR. Results indicated that RSV significantly reduced blood glucose level, increased insulin level and improved insulin sensitivity. RSV resulted in an increased serum SOD activity and caused decreased FOXO1 and FOXO3a expression in adipose tissue of rats with T2DM. Therefore, by attenuation of FOXO expression in adipose tissue of T2DM rats, RSV showed a hypoglycemic potential and antioxidant properties, and consequently ameliorated insulin resistance.

The effect of resveratrol on the histologic characteristics of the cochlea in diabetic rats

OBJECTIVES/HYPOTHESIS

The aim of this study was to investigate changes in the cochlea and the potential dose-dependent effects of resveratrol (RSV) against diabetes mellitus (DM) ototoxicity.

STUDY DESIGN

Animal model.

METHODS

Twenty-four male Wistar albino rats were divided into four groups. Baseline distortion product otoacoustic emission (DPOAE) measurements were evaluated. Group I was the control group, group II was made diabetic with single-dose streptozotocin, and groups III and IV were rendered diabetic as group II and administered 10 and 20 mg RSV, respectively, intraperitoneally for 4 weeks. All animals were sacrificed after repeated DPOAE measurement. Apoptosis was investigated using caspase-3, Bax (Bcl-associated X protein), and TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) staining.

RESULTS

The DPOAE values in the diabetic group were found to be significantly lower compared with the other groups at 5,714 Hz and 8,000 Hz (P < .05). No significant difference in otoacoustic emission was detected in the comparison of the RSV doses (P > .05). The histopathologic investigation using caspase-3, Bax, and TUNEL staining showed that the mean rank of the diabetic group was significantly higher compared with the RSV10, RSV20, and control groups (DM > RSV10 > RSV20 > control) (P < .05).

CONCLUSIONS

These results imply that RSV administration offered statistically significant protection for the cochleas of rats against diabetes. This protective effect improved histologically with higher doses.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:E1-E6, 2019.

Preventative effects of resveratrol and estradiol on streptozotocin-induced diabetes in ovariectomized mice and the related mechanisms

Resveratrol, a non-flavonoid polyphenolic compound, is structurally and functionally similar to estrogen and has drawn great attention for its potentially beneficial effects on diabetes. However, it is not known whether it shares the same protective effect against diabetes as estrogen and the underlying mechanisms. The aim of the present study was to investigate the protective effects of phytoestrogen resveratrol and exogenous 17β-estradiol against streptozotocin (STZ)-induced type 1 diabetes. Female mice were ovariectomized (OVX) and chronically injected with different concentrations of resveratrol (0.1, 1 or 10 mg/kg) and 17β-estradiol (0.01, 0.1 or 1 mg/kg) subcutaneously for 4 weeks, and the levels of blood glucose, plasma insulin, plasma antioxidant capacity, the changes of pancreatic islet cells and the expressions of glucose transporter 4 (GLUT4), insulin receptor substrate 1 (IRS-1) and phosphorylation of extracellular signal-regulated kinase (p-ERK) were detected. Resveratrol and 17β-estradiol significantly inhibited the increase of the blood glucose level and the rise of plasma malondialdehyde in STZ-induced diabetic mice, improved the levels of plasma antioxidant capacity and plasma insulin, protected the pancreatic islet cells, and increased the expressions of GLUT4 and IRS-1, but decreased p-ERK expression in skeletal muscle and myocardial tissue. The results suggest that resveratrol or 17β-estradiol shows obvious protection against STZ-induced diabetes in OVX mice, the mechanisms probably involve their ameliorating antioxidant activities and islet function, promoting muscle glucose uptake and inhibiting the expression of p-ERK.

An update on natural compounds in the remedy of diabetes mellitus: A systematic review

Herbal medicine, phytomedicine or botanical medicine are synonymous, utilizes plants intended for medicinal purposes. Medicinal use of herbal medicine in the treatment and prevention of diseases including diabetes has a long history compared to conventional medicine. Diabetes is one of the major public health concerns over the world. Diabetes or hyperglycemia is considered to be one of the common public health hazard; optimal control of which is still not possible. Persistent hyperglycemia or uncontrolled diabetes has the potential to cause serious complications such as kidney disease, vision loss, cardiovascular disease, and lower-limb amputations which contributed towards morbidity and mortality in diabetes. There are various approaches to treat and prevent diabetes as well as its secondary complications, one of it is herbal medicines. However, the selection of herbs might depends on several factors, which include the stage of progression of diabetes, types of comorbidities that the patients are having, availability, affordability as well as the safety profile of the herbs. This review focuses on the herbal and natural remedies that play the role in the treatment or prevention of this morbid disorder - diabetes, including their underlying mechanisms for the blood glucose-lowering property and the herbal products already been marketed for the remedial action of diabetes.

The antioxidant effect of mulberry and jamun fruit wines by ameliorating oxidative stress in streptozotocin-induced diabetic Wistar rats

Polyphenols act by scavenging reactive oxygen species during oxidative stress and hence are useful in the treatment of metabolic disorders including diabetes. This study describes the effect of polyphenol rich mulberry and jamun wines fed to streptozotocin-induced diabetic rats. To male adult Wistar rats, divided into groups (n = 10 per group) intraperitoneal injection was administered with streptozotocin at 38 mg per kg body weight for inducing diabetes. After confirmation of diabetes, rats divided into groups were fed each day with 5.7 milliliter per kg body weight of mulberry, jamun, white and red grape wines for 6 weeks. One group of animals received resveratrol at 20 mg per kg body weight. After six weeks of treatment, blood glucose, urinary profile, lipid profile, plasma, liver, kidney, brain and eye antioxidant enzyme activities, lipid peroxidation, non-esterified fatty acids (NEFA) and hepatic glutathione (GSH) content were determined. Though wine and resveratrol feeding did not improve the glycemic status of diabetic rats, increases in antioxidant enzymes and GSH content accompanied by reduced NEFA and lipid peroxidation were observed. The kidneys and brains of resveratrol fed rats showed significant reduction in malondialdehyde equivalents, exhibited an improved antioxidant status of tissues and an increased glutathione content. The findings suggested that the wines can ameliorate the consequences of diabetes due to their antioxidants.

Endocrine Disrupting Chemicals Mediated through Binding Androgen Receptor Are Associated with Diabetes Mellitus

Endocrine disrupting chemicals (EDCs) can mimic natural hormone to interact with receptors in the endocrine system and thus disrupt the functions of the endocrine system, raising concerns on the public health. In addition to disruption of the endocrine system, some EDCs have been found associated with many diseases such as breast cancer, prostate cancer, infertility, asthma, stroke, Alzheimer’s disease, obesity, and diabetes mellitus. EDCs that binding androgen receptor have been reported associated with diabetes mellitus in in vitro, animal, and clinical studies. In this review, we summarize the structural basis and interactions between androgen receptor and EDCs as well as the associations of various types of diabetes mellitus with the EDCs mediated through androgen receptor binding. We also discuss the perspective research for further understanding the impact and mechanisms of EDCs on the risk of diabetes mellitus.

In Vitro and In Vivo Antioxidant and Anti-Hyperglycemic Activities of Moroccan Oat Cultivars

Improvement of oat lines via introgression is an important process for food biochemical functionality. This work aims to evaluate the protective effect of phenolic compounds from hybrid Oat line (F11-5) and its parent (Amlal) on hyperglycemia-induced oxidative stress and to establish the possible mechanisms of antidiabetic activity by digestive enzyme inhibition. Eight phenolic acids were quantified in our samples including ferulic, p-hydroxybenzoic, caffeic, salicylic, syringic, sinapic, p-coumaric and chlorogenic acids. The Oat extract (2000 mg/kg) ameliorated the glucose tolerance, decreased Fasting Blood Glucose (FBG) and oxidative stress markers, including Superoxide dismutase (SOD), Catalase (CAT), Glutathione peroxidase (GPx), Glutathione (GSH) and Malondialdehyde (MDA) in rat liver and kidney. Furthermore, Metformin and Oat intake prevented anxiety, hypercholesterolemia and atherosclerosis in diabetic rats. In vivo anti-hyperglycemic effect of Oat extracts has been confirmed by their inhibitory activities on α-amylase (723.91 μg/mL and 1027.14 μg/mL) and α-glucosidase (1548.12 μg/mL & 1803.52 μg/mL) enzymes by mean of a mixed inhibition.

Anti-inflammatory and antioxidant role of resveratrol on nicotine-induced lung changes in male rats

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Nicotine decreased the antioxidant capacities in male rats.

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The lung of nicotine-treated rats showed severe congestion of the alveolar lung tissues.

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Resveratrol exerts its protective effect by alleviating the extent of oxidative status induced by nicotine.

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Resveratrol improve the enzymatic/non-enzymatic antioxidant defense system in rats treated with combination of nicotine and resveratrol.

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Resveratrol decreases the pathological changes in animals against the lung damage caused by nicotine.

Male albino rats of Wistar strain were injected intraperitoneally with nicotine or/and resveratrol for 4 weeks. Serum Interleukin-2, Interleukin-6, alpha-fetoprotein and tumor necrosis-alpha, as well as plasma 8-hydroxydeoxyguanosine of nicotine-treated rats were increased significantly. Myeloperoxidase, xanthine oxidase, nitric oxide, lipid peroxidation and total oxidative status of the lung in nicotine-treated rats were increased significantly, which were brought down to normal in resveratrol co-treated group. Endogenous antioxidant status as the activity of superoxide dismutase, catalase, glutathione peroxidase, and glucose-6-phosphate dehydrogenases were found to be decreased significantly in the lung of the nicotine-treated group, which were significantly raised in resveratrol-administered groups. The non-enzymatic antioxidants as total antioxidant and thiol levels were decreased significantly as the effect of nicotine that was effectively enhanced by resveratrol treatment. The lung of nicotine-treated rats showed severe congestion of the alveolar lung tissues with scattered congestion per bronchiolar and perivascular cells, as well as, inflammatory cells were observed. The data suggested that resveratrol exerts its protective effect by modulating the extent of oxidative status and improving the enzymatic/non-enzymatic antioxidant defense system, moreover, decreases the pathological changes in animals against the lung damage caused by nicotine.

Hypoglycaemic activity of Mathurameha, a Thai traditional herbal formula aqueous extract, and its effect on biochemical profiles of streptozotocin-nicotinamide-induced diabetic rats

BACKGROUND

The Thai traditional herbal formula-Mathurameha, consisting of 26 medicinal plants, has been used as an alternative and complementary medicine for diabetes treatment in Wangnamyen Hospital, Thailand. To provide scientific evidences on the efficacy and safety of this herbal formula, in vivo hypoglycaemic activity, effect on serum biochemical profiles and acute toxicity were investigated.

METHODS

Experimental type 2 diabetes was induced in male Sprague-Dawley rats by intraperitoneal injection of nicotinamide 15 min prior to intravenous injection of streptozotocin. The most effective extract from the oral glucose tolerant test (OGTT) was administered daily via the oral route to diabetic rats for 2 weeks. Two-hour postprandial plasma glucose (2h-PPG) levels were measured on days 0, 7, and 14. Biochemical data were measured at the end of daily oral administration experiment.

RESULTS

Aqueous extract of the herbal formula was the most potent extract for improving glucose tolerance of streptozotocin-nicotinamide-induced diabetic rats after single oral administration. After 2 weeks of daily oral administration, the aqueous extract showed a dose-dependent glucose lowering effect. At doses of 12.5, 25, and 50 mg/kg, the 2h-PPG level of diabetic rats decreased by 3.32%, 15.78%, and 17.94%, respectively. Most of the biochemical profiles of diabetic rats were improved, including the total cholesterol (TC), alkaline phosphatase (ALP), total protein, albumin, globulin, creatinine, and uric acid levels. The significantly increased triglyceride (TG) level observed in treated diabetic rats indicated a lack of a beneficial effect of the extract on lipid homeostasis. Nevertheless, there were no signs or symptoms of acute toxicity observed after oral administration of aqueous extract (5 g/kg) to both male and female rats.

CONCLUSIONS

The results revealed that the herbal formula aqueous extract has hypoglycaemic activity, beneficial effects on biochemical profiles and a lack of acute toxicity. This study confirms the efficacy and safety of the Mathurameha herbal formula used for treating type 2 diabetes mellitus.