Curcumin enhances recovery of pancreatic islets from cellular stress induced inflammation and apoptosis in diabetic rats

Potential Effect of Curcumin in Lowering Blood Glucose Level in Streptozotocin-Induced Diabetic Rats

Purpose

The prevalence of diabetes mellitus has significantly increased, with 537 million individuals living with diabetes in 2021. Curcumin, a natural compound present in turmeric, has anti-inflammatory and antioxidant properties that aid in controlling diabetes. Curcumin can lower blood glucose levels, increase pancreatic cell function, and reduce insulin resistance. The pathophysiology of diabetes involves oxidative stress and endoplasmic reticulum stress, which can lead to cell death. This study aimed to evaluate the antidiabetic activity of curcumin in rats by administering it for a month and evaluating pancreatic tissue histology.

Patients and Methods

STZ-induced diabetic rats were fed a high-fat diet containing glibenclamide, 200 mg/kg body weight (BW) curcumin, 400 mg/kg BW curcumin, or a placebo for 4 weeks. After intervention, blood glucose levels were measured, and the pancreatic tissue was examined. Blood glucose levels were measured at 0, 2, 4, 6, and 8 h.

Results

One-way ANOVA was performed to measure the mean difference among the groups at 0, 2, 4, 6, and 8 h of observation, which reported a statistically significant difference (p < 0.05). The blood glucose levels decreased after 4 h in the group receiving curcumin. Histological evaluation of the pancreas showed slight hydropic degeneration after 4 weeks of curcumin treatment.

Conclusion

Our study indicates that curcumin has a beneficial effect in diabetic rats by reducing blood glucose levels and a protective effect on the pancreas.

Role of curcumin on beta-amyloid protein, tau protein, and biochemical and oxidative changes in streptozotocin-induced diabetic rats

Diabetes is one of the most common endocrine metabolic diseases and is associated with the accumulation of beta-amyloid plaques in the brain. Amyloid beta (Aβ) and abnormal tau proteins are effective in the development of Alzheimer's disease. The aim of this study is to investigate the therapeutic and protective effects of curcumin on beta-amyloid (Aβ) accumulation and tau protein expression levels, as well as biochemical and oxidative changes in streptozotocin-induced diabetes in rats. The study comprised five groups, each consisting of eight rats: control, diabetic, curcumin, curcumin during diabetic induction, and curcumin post-diabetic induction. Groups 2 and 4 were administered a single dose of 45 mg/kg streptozotocin on day 1, while group 5 received it on day 28. Curcumin was orally administered via gavage at a dose of 100 mg/kg/day for 35 days to the third, fourth, and fifth groups. At the end of the trial (day 35), blood sugar levels and insulin resistance were similar between the control and curcumin-treated groups but significantly higher in the diabetic groups (P < 0.05). The protective effect of curcumin is tested during induction and active diabetes. The results indicated that diabetic rats displayed increased levels of Aβ, tau protein, and total oxidant capacity (TOS) compared to the curcumin-treated groups. Additionally, the total antioxidant capacity (TAS) levels were lower in the diabetic rats (P < 0.05). Aβ protein levels are lower in both the serum and brain of rats with active diabetes and treated with curcumin compared to control rats (P > 0.05). In addition, serum TAS levels were higher in rats treated with curcumin following the induction of diabetes than pre-induction of diabetes (P > 0.05). The TOS levels in the serum were higher in the rats treated with curcumin during active diabetes compared to the rats treated prior to the induction of diabetes (P < 0.05). However, no significant difference was observed in the brain. The above results show that curcumin has an effect on reducing oxidative stress caused by diabetes and increasing antioxidant activity.

Ameliorative Effects of Curcumin on Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM), a multifactorial and complicated metabolic disorder, is a growing public health problem. Numerous studies have indicated that bioactive compounds from herbal medicine have beneficial effects on T2DM prevention and treatment, owing to their numerous biological properties. Curcumin, the major curcuminoid of turmeric, is one of the most studied bioactive components of herbal supplements, and has a variety of biological activities. Clinical trials and preclinical research have recently produced compelling data to demonstrate the crucial functions of curcumin against T2DM via several routes. Accordingly, this review systematically summarizes the antidiabetic activity of curcumin, along with various mechanisms. Results showed that effectiveness of curcumin on T2DM is due to it being anti-inflammatory, anti-oxidant, antihyperglycemic, anti-apoptotic, and antihyperlipidemic, among other activities. In light of these results, curcumin may be a promising prevention/treatment choice for T2DM.

Curcumin abrogates cobalt-induced neuroinflammation by suppressing proinflammatory cytokines release, inhibiting microgliosis and modulation of ERK/MAPK signaling pathway

Curcumin, a bioactive polyphenol derived from turmeric, has been reported to have anti-inflammatory properties. The current study investigated the anti-inflammatory effect of curcumin in the hippocampal subfields (CA1 and CA3) after exposure to cobalt (Co) and the impact of ERK protein. Twenty-eight albino Wistar rats were divided into four groups, each with seven randomly selected rats as follows: Control (distilled water), Cobalt (Co) only (40 mg/kg), 120 mg/kg or 240 mg/kg curcumin + Co (40 mg/kg). Treatment was via oral gavage for 28 days. We performed a biochemical investigation to determine the levels of proinflammatory cytokines (TNFα and IL-1β). Furthermore, we conducted an immunohistochemical evaluation to assess the expression of IBA1 by microglial cells and the immunoexpression of ERK protein in the hippocampus. Results revealed a significant (p<0.05) elevation in the tissue level of TNFα and IL-1β, an increase in the number of IBA1-positive microglia, and upregulation of ERK protein in the hippocampal subfields of the rats after exposure to cobalt-only. Nevertheless, pretreatment with curcumin restored these parameters to levels comparable to control. In conclusion, our results showed that curcumin abrogated the Co-induced neuroinflammation by suppressing the release of proinflammatory biomarkers, reducing microgliosis, and modulating the ERK/MAPK pathway.

Can Polyherbal Medicine be used for the Treatment of Diabetes? - A Review of Historical Classics, Research Evidence and Current Prevention Programs

Diabetes mellitus (DM), a chronic medical condition, has attained a global pandemic status over the last few decades affecting millions of people. Despite a variety of synthetic drugs available in the market, the use of herbal medicines for managing diabetes is gaining importance because of being comparatively safer. This article reviews the result of a substantial literature search on polyherbal formulations (PHFs) developed and evaluated with potential for DM. The accumulated data in the literature allowed us to enlist 76PHFs consisting of different parts of 147 plant species belonging to 58 botanical families. The documented plant species are laden with bioactive components with anti-diabetic properties and thus draw attention. The most favoured ingredient for PHFs was leaves of Gymnema sylvestre and seeds of Trigonella foenum-graecum used in 27 and 22 formulations, respectively. Apart from herbs, shilajit (exudates from high mountain rocks) formed an important component of 9 PHFs, whereas calcined Mytilus margaritiferus and goat pancreas were used in Dolabi, the most commonly used tablet form of PHF in Indian markets. The healing properties of PHFs against diabetes have been examined in both pre-clinical studies and clinical trials. However, the mechanism(s) of action of PHFs are still unclear and considered the pitfalls inherent in understanding the benefits of PHFs. From the information available based on experimental systems, it could be concluded that plant-derived medicines will have a considerable role to play in the control of diabetes provided the challenges related to their bioavailability, bioefficacy, optimal dose, lack of characterization, ambiguous mechanism of action, and clinical efficiency are addressed.

Systemic Anti-Inflammatory Therapy Aided by Curcumin-Laden Double-Headed Nanoparticles Combined with Injectable Long-Acting Insulin in a Rodent Model of Diabetes Eye Disease

Therapeutic interventions that counter emerging targets in diabetes eye diseases are lacking. We hypothesize that a combination therapy targeting inflammation and hyperglycemia can prevent diabetic eye diseases. Here, we report a multipronged approach to prevent diabetic cataracts and retinopathy by combining orally bioavailable curcumin-laden double-headed (two molecules of gambogic acid conjugated to terminal carboxyl groups of poly(d,l-lactide-co-glycolide)) nanoparticles and injectable basal insulin. The combination treatment led to a significant delay in the progression of diabetic cataracts and retinopathy, improving liver function and peripheral glucose homeostasis. We found a concurrent reduction in lens aggregate protein, AGEs, and increased mitochondrial ATP production. Importantly, inhibition of Piezo1 protected against hyperglycemia-induced retinal vascular damage suggesting possible involvement of Piezo1 in the regulation of retinal phototransduction. Histologic evaluation of murine small intestines revealed that chronic administration of curcumin-laden double-headed nanoparticles was well tolerated, circumventing the fear of nanoparticle toxicity. These findings establish the potential of anti-inflammatory and anti-hyperglycemic combination therapy for the prevention of diabetic cataracts and retinopathy.

The high-intensity interval training (HIIT) and curcumin supplementation can positively regulate the autophagy pathway in myocardial cells of STZ-induced diabetic rats

OBJECTIVE

Targeting autophagy is a new therapeutic strategy for the complications of diabetes,such as diabetic cardiomyopathy (DCM). During diabetes, increased or insufficient autophagic activity causes aberrations in cellular homeostasis. Regarding the conflicting and unclear results regarding the effect of HIIT and curcumin supplementation on the expression of genes associated to autophagy, this study aimed to assess whether 4-week high-intensity interval training (HIIT) and curcumin supplementation are able to influence the expression of autophagy-related genes in myocardial cells of diabetic rats.

METHODS

In an experimental design, 24 male Wistar rats were randomly divided into 4 groups: non-diabetic control (NC), diabetic control (DC), diabetes + HIIT (D + HIIT), and diabetes + curcumin (D + CU). After HIIT program and curcumin treatment, the genes expression of autophagy pathway were assessed in the myocardium by real-time PCR Tanique.

RESULTS

The results indicated that the expression levels of ATG1, Beclin1, ATG5, and LAMP-2 genes were significantly reduced in the DC group compared to the NC group (p < 0.001). Following 4-week HIIT, the expression of Beclin1, ATG-5, and LAMP-2 improved considerably compared to the DC group (p < 0.001, p < 0.001, and p < 0.05, respectively). In addition, after 4 weeks of curcumin supplementation, the expression levels of ATG-5 and Beclin-1 were significantly improved compared to the DC group (p < 0.001, p < 0.05, respectively). It seems HIIT and curcumin supplementation can be an effective approach for inducing autophagy and improving cardiac function in DCM rats.However, HIIT seems more effective than curcumin in this regard.

Citrus flavanone metabolites protect pancreatic β-cells against cholesterol stress through a multi-proteomic mechanism

Citrus flavanones may improve oxidative stress and insulin resistance induced by western diets. However, there is a paucity of studies investigating the change in protein expression levels. This study evaluated the protection and the mechanisms of action of citrus flavanone metabolites, hesperetin 7-glucuronide (H7G) and 3-(4'-hydroxyphenyl) propanoic acid (PA), on pancreatic β-cell function under oxidative stress induced by cholesterol using the global proteomics approach. Cholesterol induced changes in the global proteomic profile in the pancreatic β-cell line Min6. On the other hand, proteomics analysis identified 254 proteins differentially expressed with H7G and 352 with PA treatments, most of them were opposite to the changes induced by cholesterol. Bioinformatics analysis showed that these proteins are implicated in cell functions like cell signaling (insulin signaling, p30MAPK signaling, and others), metabolism (glucokinase and glutathione metabolisms), and inflammation pathways (TNF-α and NF-κB pathways). Also, the results of molecular docking suggest that H7G and PA could bind to putative transcription factors (PPAR-γ, STAT-3, CREB1, NF-κB, NFYA) and cell signaling proteins (IKK, RAS, Pi3K, ERK), which results in changes in protein expression observed. Altogether, these data suggest that the treatment with H7G and PA protects pancreatic β-cells against stress induced by cholesterol through multi-proteomic mechanisms of action.

Reconnoitering the Therapeutic Role of Curcumin in Disease Prevention and Treatment: Lessons Learnt and Future Directions

Turmeric is a plant with a very long history of medicinal use across different cultures. Curcumin is the active part of turmeric, which has exhibited various beneficial physiological and pharmacological effects. This review aims to critically appraise the corpus of literature associated with the above pharmacological properties of curcumin, with a specific focus on antioxidant, anti-inflammatory, anticancer and antimicrobial properties. We have also reviewed the different extraction strategies currently in practice, highlighting the strengths and drawbacks of each technique. Further, our review also summarizes the clinical trials that have been conducted with curcumin, which will allow the reader to get a quick insight into the disease/patient population of interest with the outcome that was investigated. Lastly, we have also highlighted the research areas that need to be further scrutinized to better grasp curcumin’s beneficial physiological and medicinal properties, which can then be translated to facilitate the design of better bioactive therapeutic leads.

Gymnemic acid protects murine pancreatic β-cells by moderating hyperglycemic stress-induced inflammation and apoptosis in type 1 diabetic rats

Type 1 diabetes is a chronic immune-mediated disease caused by pancreatic β-cell dysfunction with consequent severe insulin deficiency. Exacerbated blood glucose levels can cause oxidative stress in the pancreatic β-cells, which leads to inflammation, and apoptosis resulting in islet dysfunction. Although massive studies have been carried out to elucidate the causative factors for β-cell damage in diabetes, the therapeutic approach to pancreatic β-cell damage has not been extensively studied. Hence, the present study has been designed to delineate the role of gymnemic acid (GA) in protecting pancreatic β-cells in diabetic animals, with special reference to inflammation and apoptosis. Our data revealed that the treatment with GA significantly reverted the alteration in both biochemical and histochemical observations in young diabetic rats. Moreover, treatment with the GA downregulates the expression of proinflammatory markers (nuclear factor-κB, tumor necrosis factor-α, interleukin-[IL]-6, and IL-1β), proapoptotic proteins (Bax, cytochrome c, and cleaved caspase-3), as well as upregulates the expression of antiapoptotic protein Bcl-2 in diabetic rats. These findings suggest that the anti-inflammatory and antiapoptotic nature of GA mitigates β-cell damage in hyperglycemic rats.

Antioxidation of a proteoglycan from Ganoderma lucidum protects pancreatic β-cells against oxidative stress-induced apoptosis in vitro and in vivo

Oxidative stress is one of the major factors in induction of pancreatic β-cell apoptosis and diabetes. Here, we investigated systematically the roles of a proteoglycan (namely, FYGL) from Ganoderma lucidum in protection and repair of pancreatic β-cells against oxidative stress-induced injury and apoptosis on molecular, cellular and animal basis. FYGL in vitro had antioxidant activity in terms of scavenging of free radicals and reduction power. FYGL improved cells viability, insulin secretion, redox indicator expressions, and mitochondrial membrane potential in H2O2-induced INS-1 cell via regulating the activations of apoptosis-related mitogen-activated protein kinases (MAPK) and nuclear factor kappa B (NF-κB) pathways as well as the insulin secretion-related pathway. Thrillingly in vivo, FYGL repaired the injured pancreas, reduced the pancreatic β-cells apoptosis, and improved insulin secretion because of regulating the balance of oxidation-reduction, therefore well managed blood glucose in db/db diabetic mice. These results demonstrated that FYGL is promising to be used as a novel natural remedy for protection of pancreatic β-cells against oxidative stress in diabetes treatment.

Mechanistic Insight into Oxidative Stress-Triggered Signaling Pathways and Type 2 Diabetes

Oxidative stress (OS) is a metabolic dysfunction mediated by the imbalance between the biochemical processes leading to elevated production of reactive oxygen species (ROS) and the antioxidant defense system of the body. It has a ubiquitous role in the development of numerous noncommunicable maladies including cardiovascular diseases, cancers, neurodegenerative diseases, aging and respiratory diseases. Diseases associated with metabolic dysfunction may be influenced by changes in the redox balance. Lately, there has been increasing awareness and evidence that diabetes mellitus (DM), particularly type 2 diabetes, is significantly modulated by oxidative stress. DM is a state of impaired metabolism characterized by hyperglycemia, resulting from defects in insulin secretion or action, or both. ROS such as hydrogen peroxide and the superoxide anion introduce chemical changes virtually in all cellular components, causing deleterious effects on the islets of β-cells, in turn affecting insulin production. Under hyperglycemic conditions, various signaling pathways such as nuclear factor-κβ (NF-κβ) and protein kinase C (PKC) are also activated by ROS. All of these can be linked to a hindrance in insulin signaling pathways, leading to insulin resistance. Hyperglycemia-induced oxidative stress plays a substantial role in complications including diabetic nephropathy. DM patients are more prone to microvascular as well as atherosclerotic macrovascular diseases. This systemic disease affects most countries around the world, owing to population explosion, aging, urbanization, obesity, lifestyle, etc. However, some modulators, with their free radical scavenging properties, can play a prospective role in overcoming the debilitating effects of OS. This review is a modest approach to summarizing the basics and interlinkages of oxidative stress, its modulators and diabetes mellitus. It may add to the understanding of and insight into the pathophysiology of diabetes and the crucial role of antioxidants to weaken the complications and morbidity resulting from this chronic disease.

Quercetin and vitamin E ameliorate cardio-apoptotic risks in diabetic rats

Apoptosis is upregulated in all forms of diabetes, and the mitochondria act as target in diabetes pathophysiology. Quercetin and vitamin E have both shown usefulness in the delay of progression of diabetes-induced complications. However, their effect on the apoptotic process in diabetes mellitus is unknown. We hypothesize that quercetin treatment in diabetes may decrease the propensity for cardiomyocytic death via regulation of the mitochondria permeability transition (mPT) pore opening. Hearts from normal and streptozotocin-induced diabetic rats were used for the study. Low ionic strength heart mitochondria were used for swelling assay and mitochondrial lipid peroxidation (mLPO) activity was spectrophotometrically assessed. Levels of cytochrome c and caspase 3 and 9 were determined by immunohistochemistry, while lesions assessed by histology. Diabetic heart mPT pore showed larger amplitude swelling than control, while mLPO levels were increased in diabetic rats relative to control, this resulted in cytochrome c release. This initiated increased caspase 3 and 9 activity in diabetic rats (p < 0.05). Histology showed hemorrhagic lesions in diabetic rat hearts. Quercetin and vitamin E treatment reversed these effects, suggestive of their anti-apoptotic effect. Quercetin and vitamin E protection in diabetes is mediated by mPT pore inhibition and modulation of mitochondrial-mediated apoptosis.

Highly active antiretroviral therapy conjugated silver nanoparticle ameliorates testicular injury in type-2 diabetic rats

Despite advances in managing human immunodeficiency virus (HIV) infection and success in the treatment prognosis using highly active antiretroviral therapy (HAART). The clinical efficacy of this regimen has been associated with increased adverse effects such as metabolic derangements and reproductive dysfunctions. These adverse effects necessitate a nanoparticle delivery vehicle like silver nanoparticles (AgNPs), a multi-functional drug delivery system, to transport the HAART to the viral reservoir site like testis. This study was therefore designed to evaluate the effects of HAART loaded AgNPs (HAART-AgNPs) on testicular oxidative stress markers, an inflammatory biomarker, and histomorphology in a rat model of diabetes. Thirty-six adult male Sprague-Dawley rats were randomly divided into two groups (n = 18) non-diabetic and fructose-streptozotocin (Frt-STZ) induced type 2 diabetes (T2DM). Thereafter, both groups were subdivided into three (n = 6) and treated with distilled water, HAART and HAART-AgNPs. HAART-AgNPs caused a significant increase (p < 0.05) in catalase (23.43 ± 0.92) level vs diabetic control (16.95 ± 1.04). Also, HAART-AgNP caused a significant reduction (p < 0.05) in malondialdehyde, interleukin-6 and blood glucose levels (1.94 ± 0.06, 93.65 ± 3.6, 287.33 ± 22.85 respectively), compared to their respective diabetic control values (2.18 ± 0.12, 143.4 ± 9.2, 372.16 ± 23.16). Furthermore, HAART-AgNPs mitigated tubular atrophy, basement membrane thickening, interstitial distension, fibrous elemental distortion and peri-interstitial tissue alterations in the testis of diabetic rats. The results from this study showed that administration of HAART-AgNPs to diabetic rats reduced testicular inflammation, improved glycaemic control, antioxidant status, and testicular histology. Therefore, conjugation of AgNP with HAART may cater for the reproductive dysfunction during the management of HIV infection.

Chlorogenic acid and β-glucan from highland barley grain ameliorate β-cell dysfunction via inhibiting apoptosis and improving cell proliferation

Recent studies have reported that highland barley as a whole grain diet has anti-hyperglycemic effects, however little information is available about the active compounds that ameliorate pancreatic β-cell dysfunction and the related mechanisms. In this study, chlorogenic acid (CA) and β-glucan (BG) were identified as the active compounds that ameliorated β-cell dysfunction. CA ameliorated β-cell dysfunction by inhibiting cell apoptosis and improving glucose-stimulated insulin secretion via targeting G protein-coupled receptor 40 (GPR40) and regulating the phospholipase C β (PLCβ) pathway. BG ameliorated β-cell dysfunction by improving cell proliferation via targeting mammalian target of rapamycin (mTOR) and regulating the protein kinase B (Akt)/glycogen synthase kinase-3β (GSK-3β) pathway. Furthermore, CA and BG improved β-cell sensitivity and pancreatic insulin secretion, and inhibited β-cell apoptosis in impaired glucose tolerance (IGT) mice. Notably, CA restored homeostasis model assessment (HOMA)-β values and Ca²⁺-ATP and K⁺-ATP levels back to normal levels, and BG at 300 mg per kg BW restored β-cell insulin contents back to normal levels in IGT mice. Additionally, the combination of CA and BG had an additive effect on ameliorating β-cell dysfunction. These results help develop whole highland barley grain as a functional food for preventing type 2 diabetes by ameliorating pancreatic β-cell damage.

In vivo therapeutic evaluation of a novel bis-lawsone derivative against tumor following delivery using mesoporous silica nanoparticle based redox-responsive drug delivery system

Herein, we have evaluated the in vivo therapeutic efficacy and systemic toxicity profile of a synthetic anticancer compound [3,3'-((4-(trifluoromethyl)phenyl)methylene)bis(2-hydroxynaphthalene-1,4-dione)]. A multifunctional mesoporous silica nanoparticle (MSN) based drug delivery network was also fabricated which specifically showed targeting nature towards the cancer cell. The mesopores of silica nanoparticles were tagged with phenyl boronic acid (PBA) for targeted drug delivery into tumor tissue. 1j was then loaded inside the nanocarriers followed by pore blocking with gold nanoparticles (GN) to attain a redox-responsive controlled drug delivery pattern. The synthesized nanocarriers (1j@-MSN-PBA-GN) having mean diameter of ~86 nm exhibited a moderate 1j loading content of 13.68% with overall negative surface charge. Both the targeted and non-targeted nanoformulations were tested for their anticancer activities both in vitro and in vivo models, and found more effective as compared with free 1j treatment. However, the targeted nanoformulations showed higher therapeutic effect due to increased cellular internalization and caused mitochondria-dependent apoptosis in MCF-7 cells via oxidative stress. Besides, the targeted nanoformulation significantly inhibited in the development of solid tumor in comparison to non-targeted nanoformulations and free 1j as a consequence of increased internalization of the drug-candidate in tumor tissue. Therefore, this study proposes that 1j can be considered as a potent anti-carcinogenic compound in vivo and its therapeutic potential is further increased by using PBA functionalized and GN gated MSN-based controlled drug delivery system without showing any significant systemic toxicity.

Quercetin improves oxidative stress-induced pancreatic beta cell alterations via mTOR-signaling

Citrus flavonoids particularly quercetin which is abundant in grapefruit, onion, green tea, berries etc. are known to have a protective effect on oxidative stress. Pancreatic β cells which synthesize and secrete insulin are prone to oxidative stress induced damage because of low cellular antioxidant enzymes. To delineate the effects of quercetin on pancreatic β cells we evaluated the protective effect of quercetin on TC6 insulinoma cells subjected to oxidative stress induced by tert-butyl-hydrogen-peroxide (TBHP). Quercetin was found to reduce TBHP induced apoptosis and trigger insulin secretion in response to glucose, in a dose-dependent manner. Quercetin treatment increased mitochondrial biogenesis, caused hypertrophy in pancreatic β cells and activated mTOR signaling with a transient change in mitochondrial membrane potential and AMP/ATP. Activation of mTOR signaling resulted in enhanced insulin secretion in TC6 cells.

Gold Nanoparticle-Bioconjugated Aminoguanidine Inhibits Glycation Reaction: An In Vivo Study in a Diabetic Animal Model

Proteins undergo glycation resulting in the generation of advanced glycation end products (AGEs) that play a central role in the onset and advancement of diabetes-associated secondary complications. Aminoguanidine (AG) acts as an antiglycating agent by inhibiting AGE generation by blocking reactive carbonyl species (RCS) like, methylglyoxal (MGO). Previous studies on antiglycating behavior of AG gave promising results in the treatment of diabetes-associated microvascular complications, but it was discontinued as it was found to be toxic at high concentrations (>10 mmol/L). The current article aims at glycation inhibition by conjugating gold nanoparticles (Gnp) with less concentration of AG (0.5-1.0 mmol/L). The HPLC results showed that AG-Gnp fairly hampers the formation of glycation adducts. Moreover, the in vivo studies revealed AG-Gnp mediated inhibition in the production of total-AGEs and -N ε -(carboxymethyl)lysine (CML) in the diabetic rat model. This inhibition was found to be directly correlated with the antioxidant parameters, blood glucose, insulin, and glycosylated hemoglobin levels. Furthermore, the histopathology of AG-Gnp-treated rats showed good recovery in the damaged pancreatic tissue as compared to diabetic rats. We propose that this approach might increase the efficacy of AG at relatively low concentrations to avoid toxicity and might facilitate to overcome the hazardous actions of antiglycating drugs.

Momordica cymbalaria improves reproductive parameters in alloxan-induced male diabetic rats

Male reproductive dysfunction is one of the common complications of diabetes mellitus that causes infertility. This study was designed to investigate the protective effect of Momordica cymbalaria (M. cymbalaria) extracts on diabetes mediated reproductive toxicity in male Wistar rats. The induction of diabetes was performed using a single intraperitoneal injection of alloxan (120 mg/kg). Skin and seed extracts (250 and 500 mg/kg) of M. cymbalaria were orally administered to alloxan-induced diabetic male rats for 28 days. Postprandial blood glucose (PBG) levels were recorded at 7-day interval for four weeks. The effects of the treatment on blood glucose, weight of reproductive organs, sperm count, testosterone levels, antioxidant capacity, and histomorphology were evaluated. Treatment with the above extracts of M. cymbalaria significantly (p < 0.05) improved the reproductive parameters as well as the antioxidant levels superoxide dismutase (SOD) and glutathione-s-transferase (GST) in the diabetic rats. Also, oral treatment with M. cymbalaria extracts significantly reduced the PBG and malondialdehyde (MDA) levels. Further, it revived the histomorphology of reproductive organs in diabetic rats. Interestingly, skin extract at a dose of 500 mg/kg was found to be more efficient in elevating the level of testosterone and sperm count in the diabetic rats. Based on the results, it is clear that M. cymbalaria not only regulates the postprandial blood glucose levels but also improves the reproductive health in the diabetic state.

Oxyberberine, an absorbed metabolite of berberine, possess superior hypoglycemic effect via regulating the PI3K/Akt and Nrf2 signaling pathways

Berberine (BBR) is a promising anti-diabetic isoquinoline alkaloid from Rhizoma coptidis, while its bioavailability was extremely low. Here, the existing form and pharmacokinetics of BBR were comparatively characterized in conventional and antibiotic-induced pseudo germ-free (PGF) rats. Furthermore, we comparatively investigated the antidiabetic effect and potential mechanism of BBR and its intestinal oxidative metabolite oxyberberine (OBB) in STZ-induced diabetic rats. Results showed that BBR and OBB existed mainly as protein-bound form in blood, while protein-bound OBB was significantly depleted in PGF rats. Treatment with OBB and BBR effectively decreased clinical symptoms of diabetic rats, reduced blood glucose level, ameliorated the pancreatic damage, and mitigated oxidative stress and inflammatory markers. However, the anti-diabetes effect of BBR was obviously compromised by antibiotics. In addition, OBB exerted superior anti-diabetes effect to BBR of the same dose, significantly up-regulated the mRNA expression of Nrf2 signaling pathway and substantially promoted the pancreatic levels of PI3K/Akt signaling pathway. In conclusion, BBR and its absorbed oxidative metabolite OBB were mainly presented and transported in the protein-bound form in vivo. The gut microbiota may play an important role in the anti-diabetes effect of BBR through transforming itself into the superior hypoglycemic metabolite OBB. OBB possessed favorable hypoglycemic and pancreatic β-cells protective effects, which may stand a huge potential to be further developed into a promising anti-diabetes candidate.

Antidiabetic Properties of Curcumin: Insights on New Mechanisms

Plant extracts have been used to treat a wide range of human diseases. Curcumin, a bioactive polyphenol derived from Curcuma longa L., exhibits therapeutic effects against diabetes while only negligible adverse effects have been observed. Antioxidant and anti-inflammatory properties of curcumin are the main and well-recognized pharmacological effects that might explain its antidiabetic effects. Additionally, curcumin may regulate novel signaling molecules and enzymes involved in the pathophysiology of diabetes, including glucagon-like peptide-1, dipeptidyl peptidase-4, glucose transporters, alpha-glycosidase, alpha-amylase, and peroxisome proliferator-activated receptor gamma (PPARγ). Recent findings from in vitro and in vivo studies on novel signaling pathways involved in the potential beneficial effects of curcumin for the treatment of diabetes are discussed in this review.

Nrf2: The Master and Captain of Beta Cell Fate

Prolonged hyperglycemia is toxic to pancreatic β cells, generating excessive reactive oxygen species, defective glucose-stimulated insulin secretion, decreased insulin production, and eventually β cell death and diabetes. Nrf2 is a master regulator of cellular responses to counteract dangerous levels of oxidative stress. Maintenance of β cell mass depends on Nrf2 to promote the survival, function, and proliferation of β cells. Indeed, Nrf2 activation decreases inflammation, increases insulin sensitivity, reduces body weight, and preserves β cell mass. Therefore, numerous pharmacological activators of Nrf2 are being tested in clinical trials for the treatment of diabetes and diabetic complications. Modulating Nrf2 activity in β cells is a promising therapeutic approach for the treatment of diabetes.

Anti-inflammatory phytochemicals for the treatment of diabetes and its complications: Lessons learned and future promise

Diabetes mellitus (type 1 and type 2) and its various complications continue to place a huge burden on global medical resources, despite the availability of numerous drugs that successfully lower blood glucose levels. The major challenging issue in diabetes management is the prevention of various complications that remain the leading cause of diabetes-related mortality. Moreover, the limited long-term durability of monotherapy and undesirable side effects of currently used anti-diabetic drugs underlie the urgent need for novel therapeutic approaches. Phytochemicals represent a rich source of plant-derived molecules that are of pivotal importance to the identification of compounds with therapeutic potential. In this review, we aim to discuss recent advances in the identification of a large array of phytochemicals with immense potential in the management of diabetes and its complications. Given that metabolic inflammation has been established as a key pathophysiological event that drives the progression of diabetes, we focus on the protective effects of representative phytochemicals in metabolic inflammation. This paper also discusses the potential of phytochemicals in the development of new drugs that target the inflammation in the management of diabetes and its complications.

Effect of punicalagin on multiple targets in streptozotocin/high-fat diet-induced diabetic mice

Type 2 diabetes has a series of metabolic aberrations accompanied by chronic hyperglycemia, along with various comorbidities. In recent reports, punicalagin from pomegranate has been reported to exert hypoglycemic effects against diabetes. The goal of the current research was to investigate the therapeutic effectiveness and elucidate the mechanisms of punicalagin underlying type 2 diabetes. Type 2 diabetes was induced by a high-fat diet (HFD) combined with streptozotocin (STZ) injection in C57BL/6J mice. Punicalagin was administered daily by oral gavage for 4 weeks. The results indicated that high FBG (fasting blood glucose), dyslipidemia and associated islet, liver and kidney injury were observed in the model group mice. Through metabolomics analysis, it was found that the administration of punicalagin could regulate 24 potential biomarkers and their related metabolic pathways. Moreover, the pathological changes in the liver and kidney were mainly mediated by reducing gluconeogenesis and increasing glycogenesis via stimulation of the PI3K/AKT signaling pathway and regulation of the HMGB-1/TLR4/NF-κB signaling pathway, which simultaneously interrelated to ten main pathological pathways. In addition, we confirmed the positive role of punicalagin in glucosamine-induced HepG2 cells and HG-induced HK-2 cells through related mechanistic studies in vitro. In conclusion, these findings suggested that the multi-effect and multi-target action mode of punicalagin had a significant hypoglycemic effect and a protective effect on diabetes mellitus. Punicalagin might serve as an alternative functional food or as a clinical supplemental therapy for the diabetic population to ameliorate metabolic syndrome.

Curcumin, a Multifaceted Hormetic Agent, Mediates an Intricate Crosstalk between Mitochondrial Turnover, Autophagy, and Apoptosis

Curcumin has extensive therapeutic potential because of its antioxidant, anti-inflammatory, and antiproliferative properties. Multiple preclinical studies in vitro and in vivo have proven curcumin to be effective against various cancers. These potent effects are driven by curcumin's ability to induce G2/M cell cycle arrest, induce autophagy, activate apoptosis, disrupt molecular signaling, inhibit invasion and metastasis, and increase the efficacy of current chemotherapeutics. Here, we focus on the hormetic behavior of curcumin. Frequently, low doses of natural chemical products activate an adaptive stress response, whereas high doses activate acute responses like autophagy and cell death. This phenomenon is often referred to as hormesis. Curcumin causes cell death and primarily initiates an autophagic step (mitophagy). At higher doses, cells undergo mitochondrial destabilization due to calcium release from the endoplasmic reticulum, and die. Herein, we address the complex crosstalk that involves mitochondrial biogenesis, mitochondrial destabilization accompanied by mitophagy, and cell death.

Fenofibrate ameliorates testicular damage in rats with streptozotocin-induced type 1 diabetes: role of HO-1 and p38 MAPK

BACKGROUND

Since diabetes mellitus type-1 (DM-1) induces testicular oxidative and inflammatory damage with finally an ultimate male infertility, and as fenofibrate (FEN) plays an important antioxidant and anti-inflammatory role, the aim of the present study was to investigate the effects of FEN on diabetes-induced reproductive damage and clarifying the underlying related mechanisms.

METHODS

DM-1 was induced in male Wistar rats by a single intraperitoneal injection of streptozotocin (50 mg/kg). FEN (100 mg/kg/day, orally) was administrated to diabetic rats for 4 weeks. Testicular damage was detected by estimation of both testicular and body weights, assessment of serum testosterone, testicular oxidative stress parameters (malondialdehyde and nitric oxide levels) and testicular oxidant defenses (reduced glutathione, superoxide dismutase and hemeoxygenase-1). Expressions of the inflammatory markers (inducible nitric oxide synthase, p38 mitogen-activated protein kinase (MAPK), tumor necrosis factor alpha, interleukin-6 and apoptotic marker (caspase-3) were evaluated in testicular tissue. Our results were confirmed by histopathological examination of testicular tissues.

RESULTS

Diabetic testicular damage was proved by both biochemical and histopathological examinations. FEN treatment reversed diabetic testicular damage; normalized the serum testosterone level, improved anti-oxidative capacity, ameliorated the pro-inflammatory cytokine expression in testicular tissue with the down regulation of p38 MAPK mediated-testicular apoptosis.

CONCLUSION

FEN treatment exerted a protective effect against streptozotocin-induced diabetic reproductive dysfunction not only through its powerful antioxidant and hypoglycemic effects, but also through its anti-inflammatory and anti-apoptotic effect via down-regulation of testicular p38 MAPK expression in diabetic rats.

Curcumin attenuates cytoplasmic/endoplasmic reticulum stress, apoptosis and cholinergic dysfunction in diabetic rat hippocampus

Diabetes mellitus (DM) is associated with the increased risk of the central nervous system complications as cerebrovascular disease, impaired cognition, dementia and neurodegeneration. Curcumin is a polyphenol with anti-oxidant, anti-inflammatory, anti-hyperlipidemic, and anti-cancer effects. Therefore, the present study was aimed to focus on the mechanistic insights of diabetes-induced hippocampal neurodegeneration in addition to shedding the light on the modulatory effect of curcumin. Twenty-eight male Wistar rats were randomly divided into four groups. Type I DM was induced by a single intra-peritoneal injection of streptozotocin (STZ) (65 mg/kg b.w.). Curcumin (100 mg/kg b.w.) was given to the diabetic group after the induction and for eight weeks. Hippocampal glucose-regulated protein 78 (GRP78), activating transcription factor 4 (ATF-4), Bcl2 and choline acetyl transferase (ChAT) genes expression were assessed. Heat shock protein 70 (HSP70), Bcl-2-Associated X protein (Bax), Interferon-γ (INF-γ) and CCAAT-enhancer-binding protein homologous protein (CHOP) levels in the hippocampus were immunoassayed, in addition to the assessment of glycemic and redox status. Curcumin significantly improved blood glucose level, redox status, cellular stress, and decreased INF-γ and Bax levels, down-regulated GRP78 and ATF-4 expression, meanwhile, up-regulated Bcl2 and ChAT expression in hippocampus. Histological findings proved the biochemical and molecular findings. Our results support curcumin as a potential neuro-protective agent against diabetes induced hippocampal neurodegeneration.

Natural antioxidants' effects on endoplasmic reticulum stress-related diseases

Endoplasmic reticulum (ER) stress is a normal molecular process induced by the over-accumulation of misfolded or unfolded proteins. ER stress induces the unfolded protein response (UPR), which reduces global protein synthesis, increases ER capacity and protein degradation, to restart ER homeostasis, allowing cell survival. However, the over-induction of UPR can also trigger inflammatory processes, tissue damage and cell death. ER stress is involved in several pathologies, like endothelial dysfunction, diabetes and heart, liver, kidney or neurological diseases. Although the progression of these diseases is the result of several pathological mechanisms, oxidative stress has been widely related to these pathologies. Moreover, ER stress can establish a progressive pathological cycle with oxidative stress. Therefore, the use of natural antioxidants, able to modulate both oxidative and ER stress, can be a new strategy to mitigate these diseases. This review is focused on the effects of natural antioxidant compounds on ER stress in endothelial dysfunction, diabetes and heart, liver, kidney or neurological diseases.

Protective efficacy of Tinospora sinensis against streptozotocin induced pancreatic islet cell injuries of diabetic rats and its correlation to its phytochemical profiles

ETHNOPHARMACOLOGICAL RELEVANCE

Tinospora sinensis Lour. (Merr.) belongs to the family Menispermaceae and its stem extract have been used traditionally in broad aspects of therapeutic remedies including debility, dyspepsia, fever, jaundice, ulcer, bronchitis, urinary disease, skin disease, liver disease and diabetes.

AIM OF THE STUDY

The aim of the study was to evaluate the protective effects of methanol extract of stem of Tinospora sinensis (METS) on streptozotocin induced pancreatic islet cell injuries of diabetic rats and its correlation to its phytochemical profiles.

MATERIALS AND METHODS

A high-performance liquid chromatography technique (HPLC) was used to identify and quantify the major phytochemicals present in the METS. Diabetic rats were administered with METS at a dose of (100, 200 and 400 mg/kg respectively orally) and standard drug Metformin (300 mg/kg) was given orally to group serving positive control. Effect of the METS on glucose homeostasis, oxidative stress, antioxidant status, histopathology of pancreas and also on intracellular reactive oxygen species (ROS), mitochondrial membrane potential, apoptosis, cell cycle of pancreatic islet cells were studied in diabetic rats.

RESULTS

The major phytochemicals identified and quantified by HPLC in the extract were berberine, caffeic acid, myricetin and ferulic acid. This result showed that methanol extract exhibited good antioxidant effect. The methanol extract of the plant prevented the diabetogenic effect of STZ and significantly lowered the fasting blood glucose level, glycated haemoglobin and increased insulin and C-peptide level in treated rats. METS reduced apoptosis of STZ treated islet cells by significantly decreasing pro-inflammatory cytokines (TNFα, IL6), intracellular ROS generation, lipid peroxidation, nitric oxide (NO) production and increasing mitochondrial membrane potential and sub-G₀ peak area, enzymatic and nonenzymatic antioxidants.

CONCLUSION

The results revealed that the methanol extract of the stem of the plant possesses protective effects against diabetes and associated complications.

Antidiabetic Properties of Curcumin I: Evidence from In Vitro Studies

Type 2 diabetes mellitus (T2DM) is a growing metabolic disease characterized by insulin resistance and hyperglycemia. Current preventative and treatment strategies for T2DM and insulin resistance lack in efficacy resulting in the need for new approaches to prevent and manage/treat the disease better. In recent years, epidemiological studies have suggested that diets rich in fruits and vegetables have beneficial health effects including protection against insulin resistance and T2DM. Curcumin, a polyphenol found in turmeric, and curcuminoids have been reported to have antioxidant, anti-inflammatory, hepatoprotective, nephroprotective, neuroprotective, immunomodulatory and antidiabetic properties. The current review (I of II) summarizes the existing in vitro studies examining the antidiabetic effects of curcumin, while a second (II of II) review summarizes evidence from existing in vivo animal studies and clinical trials focusing on curcumin’s antidiabetic properties.

Molecular mechanisms of curcumin and its analogs in colon cancer prevention and treatment

Colorectal cancer remains to be the most prevalent malignancy in humans and 1.5 million men and women living in the United States are diagnosed with colorectal cancer, with a predicted 145,600 new cases to be diagnosed in 2019. Curcuminoids and its synthetic analogs are now of interest due to their bioactive attributes, especially their action as anticancer activity in various cancer cell line models. Several in vivo and in vitro studies have substantially proved their anticancer activities against colon cancer cell lines. Curcumin analogues like IND-4, FLLL, GO-Y030 and C086 have demonstrated to produce greater cytotoxicity when experimentally studied and study results from many have been suggested to be the same. Combination of curcumin with therapeutic cancer agents like tolfenamic acid, 5-fluorouracil, resveratrol and dasatinib showed improved cytotoxicity and chemotherapeutic effect. The results propose that employment of curcumin with novel drug delivery systems like liposome, micelles and nanoparticle have been performed which could improve the therapeutic efficacy against colon cancer. The present review highlights the mechanism of action, synergistic effect and novel delivery methods to improve the therapeutic potential of curcumin.

Mangiferin ameliorates collateral neuropathy in tBHP induced apoptotic nephropathy by inflammation mediated kidney to brain crosstalk

The kidneys and brain share similarities in anatomy and vaso-regulation and exhibit clinical interactions in various diseases. To investigate the probable mechanism of kidney to brain crosstalk, we developed an in vivo model of renal injury in mice through intoxication with the oxidative stress inducer, tBHP. Proteinuria, abnormalities in the renal tubules and KIM1 activation were found in tBHP intoxicated animals. Due to this renal pathophysiology, various pro-inflammatory molecules (TNF-α, IL-1β, IL-6, ICAM-1, VCAM-1) especially TNF-α, entered into the brain from kidneys, triggering cerebral inflammatory cascades leading to behavioral anomalies in association with membrane lipid peroxidation, BBB disruption and brain morphological alterations. Moreover, increased levels of reactive oxygen species, decreased antioxidant enzyme activity and an altered GSH/GSSG ratio were found in both these organs. Here, we introduced mangiferin as a protective molecule because of its anti-inflammatory and antioxidant properties. Mangiferin via inhibition of apoptosis and activation of the PI3K/Akt pathway protected the kidneys. It restored the deleterious phenomena in the damaged brain by downregulating the JNK and p38MAPK mediated pro-apoptotic cascade and activating the intracellular antioxidant thioredoxin, thereby protecting against tBHP induced nephropathy mediated neuropathophysiology.

Mangiferin alleviates arsenic induced oxidative lung injury via upregulation of the Nrf2-HO1 axis

Arsenic contaminated drinking water consumption is a serious health issue around the world. Chronic inorganic arsenic exposure has been associated with respiratory dysfunctions. It exerts various detrimental effects, disrupting normal cellular homeostasis and turning on severe pulmonary complications. This study elucidated the role of mangiferin, a natural xanthone, against arsenic induced lung toxicity. Chronic exposure of sodium arsenite (NaAsO2) at 10 mg/kg bw for 3 months abruptly increased the LDH release in broncho-alveolar lavage fluid, generated reactive oxygen species (ROS), impaired the antioxidant defense and distorted the alveoli architecture. It caused significant inflammatory outburst and promoted the apoptotic mode of cell death via upregulating the expressions of various proapoptotic molecules related to mitochondrial, extra-mitochondrial and ER stress mediated apoptotic pathway. Activation of inflammatory cascade led to disruption of alveolar capillary barrier and impaired Na+/K+-ATPase function that led to detaining of alveolar fluid clearance activity. Mangiferin due to its anti-inflammatory activity suppressed this inflammation and reduced inflammatory cell infiltration in lung tissue. It significantly restored the antioxidant balance and inhibited apoptosis in lung via upregulating Nrf2-HO1 axis.

Human mesenchymal stem cells improve rat islet functionality under cytokine stress with combined upregulation of heme oxygenase-1 and ferritin

Background

Islets of Langerhans transplantation is a promising therapy for type 1 diabetes mellitus, but this technique is compromised by transplantation stresses including inflammation. In other tissues, co-transplantation with mesenchymal stem cells has been shown to reduce damage by improving anti-inflammatory and anti-oxidant defences. Therefore, we probed the protection afforded by bone marrow mesenchymal stem cells to islets under pro-inflammatory cytokine stress.

Methods

In order to evaluate the cytoprotective potential of mesenchymal stem cells on rat islets, co-cultures were exposed to the interleukin-1, tumour necrosis factor α and interferon γ cocktail for 24 h. Islet viability and functionality tests were performed. Reactive oxygen species and malondialdehyde were measured. Expression of stress-inducible genes acting as anti-oxidants and detoxifiers, such as superoxide dismutases 1 and 2, NAD(P)H quinone oxidoreductase 1, heme oxygenase-1 and ferritin H, was compared to non-stressed cells, and the corresponding proteins were measured. Data were analysed by a two-way ANOVA followed by a Holm-Sidak post hoc analysis.

Results

Exposure of rat islets to cytokines induces a reduction in islet viability and functionality concomitant with an oxidative status shift with an increase of cytosolic ROS production. Mesenchymal stem cells did not significantly increase rat islet viability under exposure to cytokines but protected islets from the loss of insulin secretion. A drastic reduction of the antioxidant factors heme oxygenase-1 and ferritin H protein levels was observed in islets exposed to the cytokine cocktail with a prevention of this effect by the presence of mesenchymal stem cells.

Conclusions

Our data evidenced that MSCs are able to preserve islet insulin secretion through a modulation of the oxidative imbalance mediated by heme and iron via heme oxygenase-1 and ferritin in a context of cytokine exposure.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1190-4) contains supplementary material, which is available to authorized users.

pH-responsive and targeted delivery of curcumin via phenylboronic acid-functionalized ZnO nanoparticles for breast cancer therapy

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A novel ZnO-PBA-Curcumin nanohybrid was synthesized.

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Targeted delivery was achieved in cancer cells through PBA functionalization.

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Loading curcumin onto nanoparticles increased its anticancer effects.

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The pH-dependent release of curcumin was obtained in cancer cells.

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ZnO-PBA-Curcumin nanohybrids exhibited significant anticancer activity without any systemic toxicity.

Nanoparticle-mediated targeted delivery of bioactive natural compounds has recently been gaining much interest for breast cancer therapy. Herein, phenyl boronic acid (PBA)-conjugated and pH-responsive ZnO nanoparticles (diameter ∼40 nm) were synthesized for the tumor tissue-specific delivery of curcumin. PBA conjugation facilitates the targeted delivery of curcumin to the sialic acid overexpressed in breast cancer cell membranes. Curcumin-loaded ZnO nanoparticles (ZnO-PBA-Curcumin) caused apoptotic cell death in MCF-7 human breast cancer cells by inducing oxidative stress and mitochondrial damage. Further, in vivo intravenous (i.v.) administration of ZnO-PBA-Curcumin was found to effectively decrease tumor growth in Ehrlich ascites carcinoma (EAC) tumor-bearing mice via the enhanced accumulation of curcumin. Interestingly, ZnO-PBA-Curcumin did not show any signs of systemic toxicity. The cytotoxic potential of the nanohybrid ZnO-PBA-Curcumin is attributed to the combinatorial cytotoxic effects of curcumin and ZnO in cancer cells. Collectively, ZnO-PBA-Curcumin may represent a potential treatment modality for breast cancer therapy. This study provides insight into the tumor cell targeting mechanism using PBA functionalization, and the anticancer efficacy of curcumin-loaded pH-sensitive nanohybrids can be attributed to the differential oxidative stress-inducing properties of curcumin and Zn⁺² ions.

Ferulic Acid Protects Hyperglycemia-Induced Kidney Damage by Regulating Oxidative Insult, Inflammation and Autophagy

Oxidative insult, inflammation, apoptosis and autophagy play a pivotal role in the etiology of diabetic nephropathy, a global health concern. Ferulic acid, a phytochemical, is reported to protect against varied diseased conditions. However, the ameliorative role and mechanisms of ferulic acid in averting STZ-mediated nephrotoxicity largely remains unknown. For in vivo study, a single intraperitoneal injection of streptozotocin (50 mg kg^-1 body wt.) was administered in experimental rats to induce diabetes. The diabetic rats exhibited a rise in blood glucose level as well as kidney to body weight ratio, a decrease in serum insulin level, severe kidney tissue damage and dysfunction. Elevation of intracellular ROS level, altered mitochondrial membrane potential and cellular redox balance impairment shown the participation of oxidative stress in hyperglycemia-triggered renal injury. Treatment with ferulic acid (50 mg kg^-1 body wt., orally for 8 weeks), post-diabetic induction, could markedly ameliorate kidney injury, renal cell apoptosis, inflammation and defective autophagy in the kidneys. The underlying mechanism for such protection involved the modulation of AGEs, MAPKs (p38, JNK, and ERK 1/2), NF-κB mediated inflammatory pathways, mitochondria-dependent and -independent apoptosis as well as autophagy induction. In cultured NRK-52E cells, ferulic acid (at an optimum dose of 75 μM) could counter excessive ROS generation, induce autophagy and inhibit apoptotic death of cells under high glucose environment. Blockade of autophagy could significantly eradicate the protective effect of ferulic acid in high glucose-mediated cell death. Together, the study confirmed that ferulic acid, exhibiting hypoglycemic, antioxidant, anti-inflammatory, anti-apoptotic activities and role in autophagy, could circumvent oxidative stress-mediated renal cell damage.

Effects and Underlying Mechanisms of Bioactive Compounds on Type 2 Diabetes Mellitus and Alzheimer's Disease

Type 2 diabetes mellitus is a complicated metabolic disorder characterized by hyperglycemia and glucose intolerance. Alzheimer's disease is a progressive brain disorder characterized by a chronic loss of cognitive and behavioral function. Considering the shared characteristics of both diseases, common therapeutic and preventive agents may be effective. Bioactive compounds such as polyphenols, vitamins, and carotenoids found in vegetables and fruits can have antioxidant and anti-inflammatory effects. These effects make them suitable candidates for the prevention or treatment of diabetes and Alzheimer's disease. Increasing evidence from cell or animal models suggest that bioactive compounds may have direct effects on decreasing hyperglycemia, enhancing insulin secretion, and preventing formation of amyloid plaques. The possible underlying molecular mechanisms are described in this review. More studies are needed to establish the clinical effects of bioactive compounds.

Islet Transplantation Attenuating Testicular Injury in Type 1 Diabetic Rats Is Associated with Suppression of Oxidative Stress and Inflammation via Nrf-2/HO-1 and NF-κB Pathways

Testicular structural and functional impairment is a serious complication in male diabetes mellitus (DM) patients that leads to impaired fertility in adulthood. In contrast to other endocrine therapies, islet transplantation (IT) can effectively prevent and even reverse diabetic nephropathy and myocardial damage. However, whether IT can alleviate diabetes-induced testicular injury remains unclear. In this study, we sought to investigate the effect of IT on diabetes-induced testicular damage. A diabetic rat model was established by streptozotocin injection. DM, IT, and insulin treatment (INS) groups were compared after 4 weeks of respective treatment. We confirmed that IT could effectively attenuate diabetes-induced testicular damage and recover sperm counts more extensively compared with INS in diabetic rats. In addition, significantly higher levels of superoxide dismutase (SOD) activity and lower contents of malondialdehyde (MDA) were detected in the testes of the IT group versus diabetic rats. Mechanism studies revealed that IT significantly activates the expression of Nrf-2, HO-1, and NQO-1 and inhibits upregulation of the NF-κB expression in response to DM, while INS only exhibit slight impact on the protein expression. Therefore, we speculate that IT may prevent the progression of testicular damage by downregulating oxidative stress and inhibiting inflammation via Nrf-2/HO-1 and NF-κB pathways.

Sulphur dioxide ameliorates colitis related pathophysiology and inflammation

Colitis is an inflammatory disease of the gastrointestinal tract. Inflammation, oxidative stress and cell death constitute the backbone of colitis. Most of the drugs prescribed for inflammatory bowel disease (IBD) have various side effects. In this scenario, we would like to determine the therapeutic role sulphur dioxide, a gaso-transmitter produced through the metabolism of cysteine in colitis. Colitis was induced through intrarectal administration of 2,4,6-trinitrobenzenesulfonic acid (TNBS) in male Wistar rats. Rats were administered with 0.9% saline containing Na₂SO₃ and NaHSO₃ (3:1 ratio; i.e., 0.54 mmol/kg and 0.18 mmol/kg body weight) orally 1 h after colitis induction followed by the administration of the same solution after each 12 h for 72 h. TNBS administration resulted in increased oxidative stress, NF-ĸ B and inflammasome activation, ER stress and autophagy. Moreover, TNBS administration also resulted in activation of p53 and apoptosis. SO₂ reversed all these alterations and ameliorated colitis in rats. Administration of an inhibitor of endogenous SO₂ production along with TNBS exacerbated colitis. Results suggest that down-regulation of SO₂ / glutamate oxaloacetate transaminase pathway is involved in IBD. The protective role of SO₂ in colitis is attributed to its anti-inflammatory and anti-oxidant nature. Down-regulation of SO₂/glutamate oxaloacetate transaminase pathway is involved in IBD. Since SO₂ is not toxic at low concentration and endogenously produced, it may be used with prescribed drugs for synergistic effect after intensive research. Our result demonstrated the therapeutic role of SO₂ in colitis for the first time.