Effects of S-Allylcysteine on Biomarkers of the Polyol Pathway in Rats with Type 2 Diabetes

New insights toward molecular and nanotechnological approaches to antidiabetic agents for Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disorder affecting a major class of silver citizens. The disorder shares a mutual relationship on account of its cellular and molecular pathophysiology with type-II diabetes mellitus (DM). Chronic DM increases the risk for AD. Emerging evidence recommended that resistance in insulin production develops cognitive dysfunction, which generally leads to AD. Repurposing of antidiabetic drugs can be effective in preventing and treatment of the neurodegenerative disorder. Limitations of antidiabetic drugs restrict the repurposing of the drugs for other disorders. Therefore, nanotechnological intervention plays a significant role in the treatment of neurological disorders. In this review, we discuss the common cellular and molecular pathophysiologies between AD and type-II DM, the relevance of in vivo models of type II DM in the study of AD, and the repurposing of antidiabetic drugs and the nanodelivery systems of antidiabetic drugs against AD.

Cardioprotective action of Amaranthus viridis methanolic extract and its isolated compound Kaempferol through mitigating lipotoxicity, oxidative stress and inflammation in the heart

The current study was designed to evaluate the cardio-protective efficacy of Amaranthus viridis L. methanolic extract (AVME) and kaempferol, which was isolated from AVME in isoproterenol (ISO)-induced cardiotoxicity in rats. The rats were pre-treated with AVME (250 mg/kg body weight) and kaempferol (50 mg/kg BW) for 30 days, respectively, and then administered with ISO (20 mg/100 g body weight) on the 31st and 32nd days. We assessed the protective effects of AVME and kaempferol against ISO-induced cardiotoxicity, oxidative stress, and inflammation. The study revealed that supplementation with AVME and kaempferol significantly attenuated cardiac lipotoxicity by reducing cholesterol and triglyceride levels and simultaneously increasing the levels of high-density lipoproteins. In addition, AVME and kaempferol suppressed oxidative stress by enhancing the activities of superoxide dismutase, catalase, and glutathione peroxidase in the heart. Further, they ameliorated cardiac inflammation by mitigating the production of pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, and interleukin-1β). Hence, the study results and histopathological analysis emphasized that AVME and kaempferol could be prospective prophylactic agents against ISO-induced cardiotoxicity and may be considered nutraceuticals in the prevention of cardiovascular disorders.

Effect of S-allylcysteine against diabetic nephropathy via inhibition of MEK1/2-ERK1/2-RSK2 signalling pathway in streptozotocin-nicotinamide-induced diabetic rats

OBJECTIVE

In the current study, we evaluated the ameliorative effect of S-allylcysteine (SAC) against streptozotocin (STZ)-nicotinamide (NAD)-induced diabetic nephropathy (DN) in rats and also an attempt was made to establish the molecular mechanism of SAC.

METHODS

DN rats were orally supplemented with SAC (150 mg/kg body weight) for a period of 45 days and the effect of SAC on urinary albumin excretion, metabolic parameters, and tubular injury biomarkers by ELISA, total levels and phosphorylation of MEK1/2, ERK1/2, and RSK2 by western blotting analysis in control and experimental rats were assessed.

RESULTS

From this study, we observed that SAC considerably decreased polydipsia, poly urea, polyphagia, albuminuria and the levels of urinary N-acetyl-beta-D-glucosaminidase, neutrophil gelatinase-associated lipocalin, transforming growth factor-β1 and SAC effectively altered the pathological changes in DN rats. SAC also reserved renal cortical phosphorylation of MEK1/2, ERK1/2 and RSK2.

CONCLUSION

Hence this study recommended that SAC can successfully protect the DN through regulation of MEK1/2-ERK1/2-RSK2 signalling.

Garlic (Allium sativum L.) in diabetes and its complications: Recent advances in mechanisms of action

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycemia and impaired islet secretion that places a heavy burden on the global health care system due to its high incidence rate, long disease course and many complications. Fortunately, garlic (Allium sativum L.), a well-known medicinal plant and functional food without the toxicity and side effects of conventional drugs, has shown positive effects in the treatment of diabetes and its complications. With interdisciplinary development and in-depth exploration, we offer a clear and comprehensive summary of the research from the past ten years, focusing on the mechanisms and development processes of garlic in the treatment of diabetes and its complications, aiming to provide a new perspective for the treatment of diabetes and promote the efficient development of this field.

Polyherbal Formulation Ameliorates Diabetic Cardiomyopathy Through Attenuation of Cardiac Inflammation and Oxidative Stress Via NF-κB/Nrf-2/HO-1 Pathway in Diabetic Rats

ABSTRACT

The present study was intended to evaluate the effect of polyherbal formulation (PHF) made with 3 nutraceuticals, such as Piper nigrum, Terminalia paniculata, and Bauhinia purpurea on inflammation and oxidative stress in diabetic cardiomyopathy (DCM), which is induced by streptozotocin and nicotinamide administration in rats. We supplemented DCM rats with PHF (250 and 500 mg/kg/BW) for 45 days and evaluated their effects on oxidative stress markers, proinflammatory cytokines, and messenger RNA expressions of the nuclear factor erythroid 2-related factor-2 (Nrf-2) and its linked genes [heme oxygenase-1 (HO-1), superoxide dismutase, catalase] along with inflammatory genes [tumour necrosis factor α and nuclear factor kappa B (NF-κB)]. Our study demonstrated that PHF successfully attenuated inflammation and oxidative stress via messenger RNA upregulation of Nrf-2, HO-1, superoxide dismutase, and catalase and concomitantly with downregulation of tumour necrosis factor α and NF-κB. Conversely, PHF also protected hyperglycemia-mediated cardiac damage, which was confirmed with histopathological and scanning electron microscopy analysis. In conclusion, our results suggested that PHF successfully ameliorated hyperglycemia-mediated inflammation and oxidative stress via regulation of NF-κB/Nrf-2/HO-1 pathway. Therefore, these results recommend that PHF may be a prospective therapeutic agent for DCM.

Biochanin A attenuates obesity cardiomyopathy in rats by inhibiting oxidative stress and inflammation through the Nrf-2 pathway

OBJECTIVE

In the present study, we evaluated the effect of biochanin A (BCA) on high-fat diet (HFD)-induced obesity cardiomyopathy.

METHODS

BCA (10 mg/kg body weight) was administered to HFD-induced obese rats for 30 days, and its effect on anthropometrical, morphological, plasma cardiac, and inflammatory biomarkers, along with cardiac lipid profiles was assessed.

RESULTS

Supplementation of HFD to rats significantly increased body mass index, obesity index parameters, and cardiac lipid profile along with notable oxidative stress and inflammation. Additionally, BCA treatment in obese rats demonstrated a superior therapeutic action by restoring the altered parameters to almost normal levels. Simultaneously, BCA increased the activities and mRNA expressions of enzymatic antioxidants by upregulating the Nrf-2 pathway and inhibiting the NF-κB cascade.

CONCLUSION

BCA may attenuate obesity and its associated cardiomyopathy by suppressing oxidative stress and inflammation through activation of the Nrf-2 pathway and inhibition of NF-κB activation.

Mitigating Perspectives of Asiatic Acid in the Renal Derangements of Streptozotocin-Nicotinamide Induced Diabetic Rats

BACKGROUND

The present study was conducted to evaluate the mitigating effects of Asiatic Acid (AA), on the changes in carbohydrate metabolism, insulin signaling molecules and renal function markers in Streptozotocin (STZ)-Nicotinamide (NAD) induced diabetic rats.

METHODS

AA (20 mg/kg BW) was supplemented orally to the diabetic rats for 42 days. The levels of plasma glucose, Hemoglobin (Hb), glycosylated hemoglobin (HbA1c) insulin and renal function markers, carbohydrate metabolic enzymes in the kidney and insulin signaling molecules in skeletal muscle were measured.

RESULTS

The administration of AA elicited a significant decrease in the levels of plasma glucose, insulin resistance, HbA1c, urea, uric acid, creatinine, glycogen, glycogen synthase, glucose-6- phosphatase, and fructose-1,6-bisphosphatase and a significant increase of body weight development, insulin, Hb, hexokinase, and glycogen phosphorylase and mRNA expressions of insulin signaling molecule like insulin receptor 1, insulin receptor 2 and glucose transporter-4 in the STZ-NAD induced diabetic rats. Further, the protective effect of AA was evidenced by its histological annotation of the kidney tissues.

CONCLUSION

Hence, this study concluded that AA can protect against renal dysfunction by attenuating carbohydrate metabolic disorder and subsequently enhances glucose utilization and renal function in STZ-NAD-induced diabetic rats.

Antiobesity efficacy of asiatic acid: down-regulation of adipogenic and inflammatory processes in high fat diet induced obese rats

In the current study, we evaluated the effects of Asiatic acid (AA) on lipid metabolic markers in HFD-induced obese Sprague-Dawley rat model. AA (20 mg/kg BW) was administered orally to HFD-fed rats for 42 days. Changes in body composition, glucose, insulin resistance (IR) and lipid profiles of tissues, plasma and the pattern of gene expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) and its target genes fatty-acid synthase (FAS), adipocyte protein-2 (aP2) and uncoupling protein-2 (UCP-2) and pro-inflammatory factor tumor necrosis factor (TNF)-α were observed in experimental rats. Oral administration of AA exerts therapeutic effects similar to orlistat in attenuating body weight gain, glucose, IR, plasma and tissue lipids and mRNA levels of PPAR-γ, FAS, aP2 and inflammatory factor TNF-α and increasing UCP-2 expression in HFD-fed rats. Hence, these findings concluded that AA attenuate HFD-induced obesity by modulating PPAR-γ and its target genes and regulate lipid metabolism, suggesting their possible antiobesity effects.

Diabetic cardiomyopathy: molecular mechanisms, detrimental effects of conventional treatment, and beneficial effects of natural therapy

ABSTARCT

Diabetic complications are among the largely exigent health problems currently. Cardiovascular complications, including diabetic cardiomyopathy (DCM), account for more than 80% of diabetic deaths. Investigators are exploring new therapeutic targets to slow or abate diabetes because of the growing occurrence and augmented risk of deaths due to its complications. Research on rodent models of type 1 and type 2 diabetes mellitus, and the use of genetic engineering techniques in mice and rats have significantly sophisticated for our understanding of the molecular mechanisms in human DCM. DCM is featured by pathophysiological mechanisms that are hyperglycemia, insulin resistance, oxidative stress, left ventricular hypertrophy, damaged left ventricular systolic and diastolic functions, myocardial fibrosis, endothelial dysfunction, myocyte cell death, autophagy, and endoplasmic reticulum stress. A number of molecular and cellular pathways, such as cardiac ubiquitin proteasome system, FoxO transcription factors, hexosamine biosynthetic pathway, polyol pathway, protein kinase C signaling, NF-κB signaling, peroxisome proliferator-activated receptor signaling, Nrf2 pathway, mitogen-activated protein kinase pathway, and micro RNAs, play a major role in DCM. Currently, there are a few drugs for the management of DCM and some of them have considerable adverse effects. So, researchers are focusing on the natural products to ameliorate it. Hence, in this review, we discuss the pathogical, molecular, and cellular mechanisms of DCM; the current diagnostic methods and treatments; adverse effects of conventional treatment; and beneficial effects of natural product-based therapeutics, which may pave the way to new treatment strategies. Graphical Abstract.

Antioxidant Effects and Mechanisms of Medicinal Plants and Their Bioactive Compounds for the Prevention and Treatment of Type 2 Diabetes: An Updated Review

Diabetes mellitus is a metabolic disorder that majorly affects the endocrine gland, and it is symbolized by hyperglycemia and glucose intolerance owing to deficient insulin secretory responses and beta cell dysfunction. This ailment affects as many as 451 million people worldwide, and it is also one of the leading causes of death. In spite of the immense advances made in the development of orthodox antidiabetic drugs, these drugs are often considered not successful for the management and treatment of T2DM due to the myriad side effects associated with them. Thus, the exploration of medicinal herbs and natural products as therapeutic sources for the treatment of T2DM is promoted because they have little or no side effects. Bioactive molecules isolated from natural sources have been proven to lower blood glucose levels via regulating one or more of the following mechanisms: improvement of beta cell function, insulin resistance, glucose (re)absorption, and glucagon-like peptide-1 homeostasis. In recent times, the mechanisms of action of different bioactive molecules with antidiabetic properties and phytochemistry are gaining a lot of attention in the area of drug discovery. This review article presents an update of the findings from clinical research into medicinal plant therapy for T2DM.

Reversal of high fat diet-induced obesity through modulating lipid metabolic enzymes and inflammatory markers expressions in rats

In this study, we evaluated the ameliorative potential of Cucurbita maxima seeds oil (CSO (100 mg/kg body weight)) supplementation to high fat diet (HFD)-induced obese rats for 30 days on the changes in body weight, markers of lipid metabolism such as LDL, HDL, triglycerides, total cholesterol, adiponectin, leptin, amylase, and lipase. We also investigated the effects of CSO on the changes of lipid metabolic enzymes such as fatty-acid synthase, acetyl CoA carboxylase, carnitine palmitoyl transferase-1, HMG CoA reductase, and inflammatory markers (TNF-α and IL-6). Administration of CSO revealed significant diminution in body weight gain, altered the activity, expressions of lipid marker enzymes and inflammatory markers. It demonstrated that CSO had considerably altered these parameters when evaluated with HFD control rats. In conclusion, this study suggested that CSO might ameliorate the HFD-induced obesity by altering the enzymes and mRNA expressions important to lipid metabolism.

Beneficial Role of Some Natural Products to Attenuate the Diabetic Cardiomyopathy Through Nrf2 Pathway in Cell Culture and Animal Models

Diabetic cardiomyopathy, as one of the main cardiac complications in diabetic patients, is identified to connect with oxidative stress that is due to interruption in balance between reactive oxygen species or/and reactive nitrogen species generation and their clearance by antioxidant protection systems. Transcription factor the nuclear factor erythroid 2-related factor 2 (Nrf2) plays a significant role in maintaining the oxidative homeostasis by regulating multiple downstream antioxidants. The Nrf2 plays a significant role in ARE-mediated basal and inducible expression of more than 200 genes that can be grouped into numerous categories as well as antioxidant genes and phase II detoxifying enzymes. On the other hand, activation of Nrf2 by natural and synthetic therapeutics or antioxidants has been revealed effective for the prevention and treatment of toxicities and diseases connected with oxidative stress. Hence, recently focus has been shifted toward plants and plant-based medicines in curing such chronic diseases, as they are supposed to be less toxic. In this review, we focused on the role of some natural products on diabetic cardiomyopathy through Nrf2 pathway.

Restorative potentiality of S-allylcysteine against diabetic nephropathy through attenuation of oxidative stress and inflammation in streptozotocin-nicotinamide-induced diabetic rats

AIM

In the present study, we evaluated the therapeutic potentiality of S-allylcysteine (SAC) in streptozotocin (STZ)-nicotinamide (NAD)-induced diabetic nephropathy (DN) in experimental rats.

METHODS

SAC was orally administered for 45 days to rats with STZ-NAD-induced DN; a metformin-treated group was included for comparison. Effect of SAC on body weight, organ weight, blood glucose, levels of insulin, glycated haemoglobin, and renal biochemical markers was determined. Body composition by total body electrical conductivity (TOBEC) and dual-X ray absorptiometry (DXA), kidney antioxidant analysis, real-time polymerase chain reaction, and western blot analysis of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), nuclear factor kappa B (NF-κB), interleukin (IL)-6, and tumor necrosis factor (TNF)-α; histopathological and scanning electron microscope (SEM) analysis of the kidneys were performed in both control and experimental rats.

RESULTS

SAC treatment showed significantly decreased levels of blood glucose, glycated haemoglobin, creatinine, albumin, AST, ALT, creatinine kinase, lactate dehydrogenase, and expressions of NF-κB, IL-6, and TNF-α compared with DN control rats. Furthermore, SAC administration to DN rats significantly improved body composition and antioxidant defense mechanism which was confirmed by the upregulation of mRNA and protein expressions of antioxidant genes.

CONCLUSIONS

Thus, SAC showed adequate therapeutic effect against DN by downregulation of inflammatory factors and attenuation of oxidative stress. Histological and SEM observations also indicated that SAC treatment notably reverses renal damage and protects the kidneys from hyperglycemia-mediated oxidative damage.

Anti obese potential of Cucurbita maxima seeds oil: effect on lipid profile and histoarchitecture in high fat diet induced obese rats

In this study, we made an attempt to evaluate the potential of Cucurbita maxima seeds oil (CSO) against high-fat diet (HFD)-induced obesity in rats. We investigated the effect of CSO (100 mg/kg body weight) supplementation over 30 days on the changes of HFD-induced obese rats in body weight, biochemical parameters and lipid profile as well as investigated the effects of CSO on the histopathological changes. Oral administration with CSO revealed significant diminution in body weight gain, glucose and insulin levels, which altered the activity of lipid profile and restored the pathological alterations. It demonstrated that CSO had considerably altered these parameters when evaluated with HFD control rats. In conclusion, this study established that CSO prevents the HFD-induced obesity by altering the markers important to lipid metabolism.

Obesity-alleviating potential of asiatic acid and its effects on ACC1, UCP2, and CPT1 mRNA expression in high fat diet-induced obese Sprague-Dawley rats

The present study evaluated the effects of asiatic acid (AA), a pentacyclic triterpenoid from Centella asiatica on lipid metabolism parameters in a rat model of obesity induced using a high fat diet (HFD) for 42 days. AA (20 mg/kg body weight [BW]) was administered orally once daily for 42 days, and an orlistat-treated group of rats (10 mg/kg BW) was included for comparison. Changes in BW, blood glucose levels, insulin resistance and leptin, adiponectin, amylase, and lipase levels in the blood; lipid profiles of plasma; liver antioxidants levels; and acetyl CoA carboxylase(ACC), uncoupling protein-2 (UCP2), and carnitine palmitoyltransferase-1 (CPT1) mRNA expression were observed in the experimental rats. Our results revealed that AA (20 mg/kg BW), similar to orlistat, reduced the increase in BW; increased bone mineral contents and bone mineral densities; reduced blood glucose levels, insulin resistance, leptin, plasma lipid levels; increased adiponectin, amylase, lipase levels in the blood; showed antioxidant activity; and altered mRNA expression of lipid metabolism-related genes, including ACC, UCP 2, and CPT 1, in the HFD-fed rats. From these results, we concluded that AA possesses significant anti-obesity potential through the suppression of BW gain, lipid lowering action, development of insulin and leptin sensitivity, antioxidant activity, and increased mRNA expression of lipid metabolism-related genes.

Functional Oil from Black Seed Differentially Inhibits Aldose-reductase and Ectonucleotidase Activities by Up-regulating Cellular Energy in Haloperidol-induced Hepatic Toxicity in Rat Liver

In this study, the effect of rate-limiting enzymes involved in degradation of hepatic adenosine and intracellular sorbitol was investigated in rats exposed to haloperidol (HAL) and treated with functional oil (FO), containing principal active phytochemicals from black seed. Animals were divided into six groups (n=10): Distilled water, HAL 15 mg/kg, pre-administration/HAL 15 mg/kg, co-administration/HAL 15 mg/kg, post-administration/HAL 15 mg/kg, FO 150 mg/kg. The results of this study revealed that the activities of ectonucleotidase and aldose-reductase were significantly increased in HAL-treated rats when compared with the control (p < 0.05). However, differential treatments (pre, co and post) with FO depleted the activities of these enzymes compared with HAL-treated rats. Furthermore, therapeutic HAL administration increased the levels of key hepatic biomarkers (ALT, AST, and ALP) and malondialdehyde level with a concomitant decrease in functional hepatic cellular ATP. However, differential treatment with FO increases hepatic ATP and non-enzymatic antioxidant status, with a concomitant decrease in the levels of malondialdehyde and liver biomarkers. Therefore, results of this finding underlined the importance of aldose-reductase and econucleotidase activities in HAL induced toxicity and suggest some possible mechanisms of action by which FO prevent HAL-induced hepatic toxicity in rats.

Reversal of endothelial dysfunction in aorta of streptozotocin-nicotinamide-induced type-2 diabetic rats by S-Allylcysteine

Dietary measures and plant-based therapies as prescribed by native systems of medicine have gained attraction among diabetics with claims of efficacy. The present study investigated the effects of S-Allylcysteine (SAC) on body weight gain, glucose, insulin, insulin resistance, and nitric oxide synthase in plasma and argininosuccinate synthase (AS) and argininosuccinate lyase (ASL), lipid peroxides and antioxidant enzymes in aorta of control and streptozotocin-nicotinamide (STZ-NA)-induced diabetic rats. Changes in body weight, glucose, insulin, insulin resistance, and antioxidant profiles of aorta and mRNA expressions of nitric oxide synthase, AS, and ASL were observed in experimental rats. SAC (150 mg/kg b.w) showed its therapeutic effects similar to gliclazide in decreasing glucose, insulin resistance, lipid peroxidation, and increasing body weight; insulin, antioxidant enzymes, and mRNA levels of nitric oxide synthase, argininosuccinate synthase, and argininosuccinate lyase genes in STZ-NA rats. Histopathologic studies also revealed the protective nature of SAC on aorta. In conclusion, garlic and its constituents mediate the anti-diabetic potential through mitigating hyperglycemic status, changing insulin resistance by alleviating endothelial dysregulation in both plasma and tissues.

Preparation of S-Allylcysteine-Enriched Black Garlic Juice and Its Antidiabetic Effects in Streptozotocin-Induced Insulin-Deficient Mice

S-Allylcysteine (SAC), produced in large amounts during the aging process of garlic via enzymatic hydrolysis, is known as a key compound responsible for the multiple pharmacological activities of aged black garlic. This study investigated the effects of enzyme- and high hydrostatic pressure (HHP)-assisted extraction on the content of the bioactive compounds, including SAC, in black garlic juice (BGJ) and evaluated the antidiabetic effects of SAC-enriched BGJ in streptozotocin (STZ)-treated mice. The aging process increased the contents of SAC, total polyphenols, and total flavonoids in garlic juice. More importantly, pretreatment of pectinase cocktail with HHP resulted in a greater increase in those compounds during aging. Enzyme-treated BGJ reduced hyperglycemia and improved islet architecture and β-cell function in STZ-treated mice. Moreover, these effects were more potent than those of BGJ prepared by the conventional aging process. These findings provide useful information for the production of black garlic with improved bioactivities.