Mesoporous Silica Nanoparticles: Drug Delivery Vehicles for Antidiabetic Molecules.

Mesoporous silica nanoparticles (MSNs) are promising nanomaterials that are widely used in biomedical applications like drug delivery, diagnosis, bio-sensing and cell tracking. MSNs have been investigated meticulously in the drug-delivery field due to their unique chemical and pharmacokinetic properties, such as highly ordered mesopores, high surface area and pore volume, tuneable pore size, stability, surface functionalisation, and biocompatibility. MSN-based nanocomposites have been used to deliver therapeutic molecules like insulin, GLP-1, exenatide, DPP-4 inhibitor and plasmid-containing GLP-1 genes for managing diabetes mellitus for the last decade. The functionalisation properties of MSNs make them substantially capable of the co-delivery, controlled delivery and stimuli-responsive delivery of antidiabetic drugs. This review focuses on the delivery of antidiabetic therapeutics with special emphasis on the functionalisation of MSNs and stimuli-responsive delivery.

Beneficial effect of the methanolic leaf extract of Allium hookeri on stimulating glutathione biosynthesis and preventing impaired glucose metabolism in type 2 diabetes.

Oxidative stress resulting from the depletion of glutathione (GSH) level plays a vital role in generating various degenerative diseases, including type 2 diabetes (T2D). We tested the hypothesis that depleted glutathione levels can be enhanced and the impaired glucose metabolism can be prevented by supplementing Allium hookeri, a herb rich in organosulfur compounds, in a High Fat (HF) diet-induced T2D Male Sprague Dawley rat model. The experimental rats were divided into three groups (n = 6), namely normal diet, high-fat diet, and high-fat diet treated with A.hookeri methanolic leaf extract (250 mg/kg). Consumption of HF diet along with the plant extract resulted in significant reduction of the body weight (7.08%-14.89%) and blood glucose level (6.5%-16.4%) from the 13th week onward. There was a significant decrease in reactive oxygen species, oxidized glutathione (GSSG) levels, and an increase in GSH level in skeletal muscle tissues supplemented with the plant extract. The protein expressions of the signaling molecules such as GCLC and GR involved in GSH synthesis and of GLUT4 in glucose transport were also upregulated in the skeletal muscle tissues of the plant extract-treated group. Results of in vitro studies with muscle cell line (L6) further demonstrated the beneficial effect of the plant extract in increasing glucose uptake and maintaining the GSH/GSSH equilibrium via regulation of protein expression of GCLC/GR/GLUT4 signaling molecules in sodium palmitate (0.75 mM) treated cells. Overall this study suggests that dietary supplementation with Allium hookeri, can restore the glutathione level and regulate the blood glucose level in T2D.

Astragalin mediates the pharmacological effects of Lysimachia candida Lindl on adipogenesis via downregulating PPARG and FKBP51 signaling cascade.

Metabolic disturbances in different tissue cells and obesity are caused by excessive calorie intake, and medicinal plants are potential sources of phytochemicals for combating these health problems. This study investigated the role of methanolic extract of the folklore medicinal plant Lysimachia candida (LCM) and its phytochemical, astragalin, in managing obesity in vivo and in vitro. Administration of LCM (200 mg/kg/body weight) daily for 140 days significantly decreased both the body weight gain (15.66%) and blood triglyceride and free fatty acid levels in high-fat-diet-fed male Wistar rats but caused no substantial change in leptin and adiponectin levels. The protein expression of adipogenic transcription factors in visceral adipose tissue was significantly reduced. Further, the 3T3-L1 cell-based assay revealed that the butanol fraction of LCM and its isolated compound, astragalin, exhibited antiadipogenic activity through downregulating adipogenic transcription factors and regulatory proteins. Molecular docking studies were performed to depict the possible binding patterns of astragalin to adipogenesis proteins. Overall, we show the potential antiobesity effects of L. candida and its bioactive compound, astragalin, and suggest clinical studies with LCM and astragalin.

Synthesis and biomedical applications of nanoceria, a redox active nanoparticle.

BACKGROUND: Nanoceria has recently received much attention, because of its widespread biomedical applications, including antibacterial, antioxidant and anticancer activity, drug/gene delivery systems, anti-diabetic property, and tissue engineering. MAIN BODY: Nanoceria exhibits excellent antibacterial activity against both Gram-positive and Gram-negative bacteria via the generation of reactive oxygen species (ROS). In healthy cells, it acts as an antioxidant by scavenging ROS (at physiological pH). Thus, it protects them, while in cancer cells (under low pH environment) it acts as pro-oxidant by generating ROS and kills them. Nanoceria has also been effectively used as a carrier for targeted drug and gene delivery in vitro and in vivo models. Besides, nanoceria can also act as an antidiabetic agent and confer protection towards diabetes-associated organ pathophysiology via decreasing the ROS level in diabetic subjects. Nanoceria also possesses excellent potential in the field of tissue engineering. In this review, firstly, we have discussed the different methods used for the synthesis of nanoceria as these are very important to control the size, shape and Ce3+/Ce4+ ratio of the particles upon which the physical, chemical, and biological properties depend. Secondly, we have extensively reviewed the different biomedical applications of nanoceria with probable mechanisms based on the literature reports. CONCLUSION: The outcome of this review will improve the understanding about the different synthetic procedures and biomedical applications of nanoceria, which should, in turn, lead to the design of novel clinical interventions associated with various health disorders.

1,25(OH)2-vitamin D3 upregulates glucose uptake mediated by SIRT1/IRS1/GLUT4 signaling cascade in C2C12 myotubes.

This study examined the hypothesis that 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) upregulates the insulin-independent signaling cascade of glucose metabolism. C2C12 myotubes were treated with high glucose (HG, 25 mM) and 1,25(OH)2D3 (0-50 nM). 1,25(OH)2D3 supplementation upregulated both insulin-independent (SIRT1) and insulin-dependent (p-IRS) signaling molecules, and stimulated the GLUT4 translocation, and glucose uptake in HG-treated myotubes. The effect of 1,25(OH)2D3 on IRS1 phosphorylation, GLUT4 translocation, and glucose uptake was attenuated in SIRT1-knockdown myotubes. Treatment with 1,25(OH)2D3, coupled with insulin, enhanced GLUT4 translocation and glucose uptake compared to treatment with either insulin or 1,25(OH)2D3 alone in HG-treated myotubes, which suggests that insulin-independent signaling molecules can contribute to the higher glucose metabolism observed in 1,25(OH)2D3 and insulin-treated cells. The data, therefore, suggest that 1,25(OH)2D3 increases glucose consumption by inducing SIRT1 activation, which in turn increases IRS1 phosphorylation and GLUT4 translocation in myotubes.

Efflux pump inhibition by 11H-pyrido[2,1-b]quinazolin-11-one analogues in mycobacteria.

Mycobacterium tuberculosis infection causes 1.8 million deaths worldwide, of which half a million has been diagnosed with resistant tuberculosis (TB). Emergence of multi drug resistant and extensive drug resistant strains has made all the existing anti-TB therapy futile. The major involvement of efflux pump in drug resistance has made it a direct approach for therapeutic exploration against resistant M. tuberculosis. This study demarcates the role of 11H-pyrido[2,1-b]quinazolin-11-one (quinazolinone) analogues as efflux pump inhibitor in Mycobacterium smegmatis. Sixteen quinazolinone analogues were synthesized by treating 2-aminopyridine and 2-fluorobenzonitrile with KtOBu. Analogues were tested, and 3a, 3b, 3c, 3g, 3j, 3l, 3m, and 3p were found to modulate EtBr MIC by >4 whereas 3a, 3g, 3i and 3o showed >4 modulation on norfloxacin MIC. 3l and 3o in addition to their very low toxicity they showed high EtBr and norfloxacin accumulation respectively. Time kill curve showed effective log reduction in colony forming unit in presence of these analogues, thus confirming their role as efflux pump inhibitor. Through docking and alignment studies, we have also shown that the LfrA amino acid residues that the analogues are interacting with are present in Rv2333c and Rv2846c of M. tuberculosis. This study have shown for the first time the possibility of developing the 11H-pyrido[2,1-b]quinazolin-11-one analogues as efflux pump inhibitors for M. smegmatis and hence unbolts the scope to advance this study against resistant M. tuberculosis as well.

Vitamin D supplementation inhibits oxidative stress and upregulate SIRT1/AMPK/GLUT4 cascade in high glucose-treated 3T3L1 adipocytes and in adipose tissue of high fat diet-fed diabetic mice.

This study examined the hypothesis that vitamin-D prevents oxidative stress and upregulates glucose metabolism via activating insulin-independent signaling molecules in 3T3-L1 adipocytes and in high fat diet (HFD)-fed mice. To investigate the mechanism 3T3L1 adipocytes were treated with high glucose (HG, 25 mM) and 1,25(OH)2D3 (1,25-dihydroxyvitamin D3) (0-50 nM). Results showed that 1,25(OH)2D3 supplementation decreased NOX4 expression, ROS production, NF-κB phosphorylation, and increased the expression of Nrf2 and Trx in HG-treated cells. 1,25(OH)2D3 supplementation upregulated SIRT1 expression and AMPK phosphorylation and stimulated the IRS1/PI3K/PIP3/AKT/PKCζ signaling cascade, GLUT4 expression, and glucose uptake in HG-treated adipocytes. The effect of 1,25(OH)2D3 on the phosphorylation of both AMPK and IRS1, GLUT4 expression, and glucose uptake was significantly inhibited in SIRT1-knockdown adipocytes. This suggests the role of insulin-independent signaling molecules (SIRT1, AMPK) in mediating the effect of 1,25(OH)2D3 on the signaling cascade of glucose uptake. In addition, cholecalciferol supplementation significantly upregulated pAMPK, SIRT-1 and GLUT-4 levels in adipose tissue of mice fed with HFD. This study demonstrates a novel molecular mechanism by which vitamin-D can prevent oxidative stress and upregulates glucose uptake via SIRT1/AMPK/IRS1/GLUT4 cascade in HG-treated adipocytes and in adipose tissue of HFD diabetic mice.

Decreased cystathionine-γ-lyase (CSE) activity in livers of type 1 diabetic rats and peripheral blood mononuclear cells (PBMC) of type 1 diabetic patients.

The liver plays a major role in the formation of H2S, a novel signaling molecule. Diabetes is associated with lower blood levels of H2S. This study investigated the activities of cystathionine-γ-lyase (CSE, the enzyme that catalyzes H2S formation) in livers of type 1 diabetic (T1D) animals and in peripheral blood mononuclear cells (PBMC) isolated from T1D patients. T1D is associated with both hyperketonemia (acetoacetate and ß-hydroxybutyrate) and hyperglycemia. This study also examined the role of hyperglycemia and hyperketonemia per se in decreased CSE activity using U937 monocytes and PBMC isolated from healthy subjects. Livers from streptozotocin-treated T1D rats demonstrated a significantly higher reactive oxygen species production, lower CSE protein expression and activity, and lower H2S formation compared with those of controls. Studies with T1D patients showed a decrease in CSE protein expression and activity in PBMC compared with those of age-matched normal subjects. Cell culture studies demonstrated that high glucose (25 mm) and/or acetoacetate (4 mm) increased reactive oxygen species, decreased CSE mRNA expression, protein expression, and enzymatic activity, and reduced H2S levels; however, ß-hydroxybutyrate treatment had no effect. A similar effect, which was also observed in PBMC treated with high glucose alone or along with acetoacetate, was prevented by vitamin D supplementation. Studies with CSE siRNA provide evidence for a relationship between impaired CSE expression and reduced H2S levels. This study demonstrates for the first time that both hyperglycemia and hyperketonemia mediate a reduction in CSE expression and activity, which can contribute to the impaired H2S signaling associated with diabetes.

Phosphatidylinositol-3,4,5-triphosphate and cellular signaling: implications for obesity and diabetes.

Phosphatidylinositol-3,4,5-triphosphate (PtdIns(3,4,5)P3) is one of the most important phosphoinositides and is capable of activating a wide range of proteins through its interaction with their specific binding domains. Localization and activation of these effector proteins regulate a number of cellular functions, including cell survival, proliferation, cytoskeletal rearrangement, intracellular vesicle trafficking, and cell metabolism. Phosphoinositides have been investigated as an important agonist-dependent second messenger in the regulation of diverse physiological events depending upon the phosphorylation status of their inositol group. Dysregulation in formation as well as metabolism of phosphoinositides is associated with various pathophysiological disorders such as inflammation, allergy, cardiovascular diseases, cancer, and metabolic diseases. Recent studies have demonstrated that the impaired metabolism of PtdIns(3,4,5)P3 is a prime mediator of insulin resistance associated with various metabolic diseases including obesity and diabetes. This review examines the current status of the role of PtdIns(3,4,5)P3 signaling in the regulation of various cellular functions and the implications of dysregulated PtdIns(3,4,5)P3 signaling in obesity, diabetes, and their associated complications.

Effect of PIP3 on adhesion molecules and adhesion of THP-1 monocytes to HUVEC treated with high glucose.

BACKGROUND: Phosphatidylinositol-3,4,5-triphosphate (PIP3), a well-known lipid second messenger, plays a key role in insulin signaling and glucose homeostasis. Using human umbilical vein endothelial cells (HUVEC) and THP-1 monocytes, we tested the hypothesis that PIP3 can downregulate adhesion molecules and monocyte adhesion to endothelial cells. METHODS: HUVEC and monocytes were exposed to high glucose (HG, 25 mM, 20 h) with or without PIP3 (0-20 nM), or PIT-1 (25 µM), an inhibitor of PIP3. RESULTS: Both HG and PIT-1 caused a decrease in cellular PIP3 in monocytes and HUVEC compared to controls. Treatment with PIT-1 and HG also increased the ICAM-1 (intercellular adhesion molecule 1) total protein expression as well as its surface expression in HUVEC, CD11a (a subunit of lymphocyte function-associated antigen 1, LFA-1) total protein expression as well as its surface expression in monocytes, and adhesion of monocytes to HUVEC. Exogenous PIP3 supplementation restored the intracellular PIP3 concentrations, downregulated the expression of adhesion molecules, and reduced the adhesion of monocytes to HUVEC treated with HG. CONCLUSION: This study reports that a decrease in cellular PIP3 is associated with increased expression of adhesion molecules and monocyte-endothelial cell adhesion, and may play a role in the endothelial dysfunction associated with diabetes.

Alleviation of Diabetic Retinopathy by Glucose-Triggered Delivery of Vitamin D via Dextran-Gated Functionalized Mesoporous Silica Nanoparticles.

Diabetic retinopathy (DR) is the most common retinal disorder, developed in 35% of patients with diabetes mellitus. Lower serum levels of 25-hydroxyvitamin D are associated with the increased risk of developing DR. High doses of the active form of vitamin D (VD), on the contrary, for a long period of time may lead to hypercalcemia and an imbalance in the regulation of bone metabolism. Herein, we studied the efficacy of dextran-gated carboxyphenylboronic acid (CPBA)-functionalized mesoporous silica nanoparticles (MSNs) for glucose-sensitive delivery of 1,25-dihydroxyvitamin D3 to modulate cellular oxidative stress and inflammation for managing DR. The physical adsorption technique was employed to load VD onto nanoparticles (263.63 µg/mg (w/w)). In the presence of glucose, the dextran molecules detach from pores, allowing VD to release since glucose has 1,2-cis diol groups which have very high affinity to CPBA. Approximately 75% of VD was released upon exposure to 25 mM glucose at a time point of 10 h, demonstrating glucose-responsive delivery. Furthermore, MSN-CPBA was able to deliver VD in a glucose-dependent manner and improve the bioavailability of VD. In high-glucose-supplemented human retinal cells, MSN-CPBA increased the bioavailability of VD and reduced cellular oxidative stress and inflammation. The results suggested that the VD-loaded nanocarrier exerted remarkable therapeutic capacity in reducing the risk of developing DR. By using MSN-CPBA as a delivery platform with dextran gating, the research proposes an effective treatment approach for improving the bioavailability and effectiveness of a hydrophobic molecule in the treatment of DR.

Anti-diabetic and anti-urease inhibition potential of Amomum dealbatum Roxb. seeds through a bioassay-guided approach.

Using HPLC-PDA and HRMS analysis, five compounds p-coumaric acid, sinapic acid, quercetin, trans-ferulic and gallic acid were identified in seeds of Amomum dealbatum Roxb. The GC-MS analysis identified 1-dodecanol, phenol, 3,5-bis(1,1-dimethylethyl), Oleic Acid and 1-Heptacosanol which possess anti-diabetic properpties. A bioassay-guided technique was used to determine the degree of inhibition that A. dealbatum seeds crude methanol extract and its most active sub-fraction had against the α-glucosidase and Helicobacter pylori urease enzymes. In the Rat L6 myoblast cell line, glucose absorption through the GLUT4 transporter of most active subfraction (EASF80) was examined. According to a molecular docking investigation, these compounds strongly interacted with the GLUT4 transporter, H pylori and α-glucosidase enzyme. Sinapic acid interacted most strongly with the H. pylori urease enzyme while gallic acid interacted with both the α-glucosidase enzyme and the GLUT4 transporter. Additionally, a molecular docking simulation study was carried out to recognise the stability of the complexes.

Antihyperglycemic and antihyperlipidemic effects of fruit extract of Hodgsonia heteroclita (Roxb.) Hook. f. & Thomson in diabetic mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Hodgsonia heteroclita has been known as an important traditionally consumed medicinal plant of North-East India known to have antidiabetic properties. This study aims to investigate the effects of the ethanolic fruit extract of Hodgsonia heteroclita against hyperglycemia and hyperlipidemia by using streptozotocin (STZ) treated diabetic mice. MATERIALS AND METHODS: The fruits of H. heteroclita were collected from the various parts of Kokrajhar district, Assam India (Geographic coordinates: 26°24'3.85″ N 90°16'22.30″ E). Basic morphological evaluations were carried out by the Botanical Survey of India, Eastern circle, Shillong, who also certified and identified the plant. Hexane, chloroform, and ethanolic extracts of the fruit of H. heteroclita were investigated for α-amylase inhibition assay as a rapid screening tool for examining anti-diabetic activity. The efficacy of ethanolic extract at a dose of 100, 200, and 300 mg/kg body weight was tested for 21 days in STZ-induced diabetic mice. The body weight, fasting plasma glucose and serum lipids, and hepatic glycogen levels were measured in experimental animals to examine the antihyperglycemic and antihyperlipidemic efficacy of the extract. Both HPTLC and LC-MS analysis was performed to examine the phyotochemicals present in the ethanolic extract of H. heteroclita. RESULTS: It has been observed that treatment with the ethanolic extract dose-dependently reduced the plasma glucose levels, total cholesterol, low density lipoprotein-cholesterol, very low-density lipoprotein-cholesterol, triglyceride, and increased the body weight, liver glycogens and high-density lipoprotein-cholesterol in STZ treated diabetic mice. HPTLC demonstrated the presence of triterpene compounds and LC-MS analysis revealed the presence Cucurbitacin I, Cucurbitacin E, and Kuguacin G as the triterpene phytoconstituents. CONCLUSION: The present study demonstrated that ethanolic fruit extract of H. heteroclita improved both glycemic and lipid parameters in mice model of diabetes.

Hexagonal Boron Nitride Quantum Dots Embedded on Layer-by-Layer Films for Peroxidase-Assisted Colorimetric Detection of ß-Galactosidase Producing Pathogens.

Pathogen detection has become a major research area all over the world for water quality surveillance and microbial risk assessment. Therefore, designing simple and sensitive detection kits plays a key role in envisaging and evaluating the risk of disease outbreaks and providing quality healthcare settings. Herein, we have designed a facile and low-cost colorimetric sensing strategy for the selective and sensitive determination of ß-galactosidase producing pathogens. The hexagonal boron nitride quantum dots (h-BN QDs) were established as a nanozyme that showed prominent peroxidase-like activity, which catalyzes 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by H2O2. The h-BN QDs were embedded on a layer-by-layer assembled agarose biopolymer. The ß-galactosidase enzyme partially degrades ß-1,4 glycosidic bonds of agarose polymer, resulting in accessibility of h-BN QDs on the solid surface. This assay can be conveniently conducted and analyzed by monitoring the blue color formation due to TMB oxidation within 30 min. The nanocomposite was stable for more than 90 days and was showing TMB oxidation after incubating it with Escherichia coli (E. coli). The limit of detection was calculated to be 1.8 × 106 and 1.5 × 106 CFU/mL for E. coli and Klebsiella pneumonia (K. pneumonia), respectively. Furthermore, this novel sensing approach is an attractive platform that was successfully applied to detect E. coli in spiked water samples and other food products with good accuracy, indicating its practical applicability for the detection of pathogens in real samples.

Vitamin D up-regulates glucose transporter 4 (GLUT4) translocation and glucose utilization mediated by cystathionine-γ-lyase (CSE) activation and H2S formation in 3T3L1 adipocytes.

A scientific explanation for the beneficial role of vitamin D supplementation in the lowering of glycemia in diabetes remains to be determined. This study examined the biochemical mechanism by which vitamin D supplementation regulates glucose metabolism in diabetes. 3T3L1 adipocytes were treated with high glucose (HG, 25 mm) in the presence or absence of 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) (25, 50 nm), the active form of vitamin D. 1,25(OH)(2)D(3) treatment caused significant up-regulation of GLUT4 total protein expression and its translocation to cell surface, and an increase in glucose uptake as well as glucose utilization in HG-treated cells. 1,25(OH)(2)D(3) also caused cystathionine-γ-lyase (CSE) activation and H(2)S formation in HG-treated adipocytes. The effect of 1,25(OH)(2)D(3) on GLUT4 translocation, glucose utilization, and H(2)S formation was prevented by propargylglycine, an inhibitor of CSE that catalyzes H(2)S formation. Studies using antisense CSE also demonstrated the inhibition of GLUT4 translocation as well as glucose uptake and utilization in 1,25(OH)(2)D(3)-supplemented CSE-siRNA-transfected adipocytes compared with controls. 1,25(OH)(2)D(3) treatment along with insulin enhanced GLUT4 translocation and glucose utilization compared with either insulin or 1,25(OH)(2)D(3) alone in HG-treated adipocytes. 1,25(OH)(2)D(3) supplementation also inhibited monocyte chemoattractant protein-1 and stimulated adiponectin secretion in HG-treated adipocytes, and this positive effect was prevented in propargylglycine-treated or CSE-knockdown adipocytes. This is the first report to demonstrate that 1,25(OH)(2)D(3) up-regulates GLUT4 translocation and glucose utilization and decreases inflammatory markers, which is mediated by CSE activation and H(2)S formation in adipocytes. This study provides evidence for a novel molecular mechanism by which 1,25(OH)(2)D(3) can up-regulate the GLUT4 translocation essential for maintenance of glucose metabolism.

L-cysteine and hydrogen sulfide increase PIP3 and AMPK/PPARγ expression and decrease ROS and vascular inflammation markers in high glucose treated human U937 monocytes.

Diabetic patients have lower blood levels of L-cysteine (LC) and hydrogen sulfide (H2 S) and a higher incidence of vascular inflammation. This study examined whether impaired LC or H2S levels affect vascular inflammation markers in diabetes. Human U937 monocytic cells were treated with high-glucose (HG, 25 mM, 20 h) in the presence or absence of LC (100, 500, or 1,000 µM, an endogenous precursor of H2 S) or Na2S (5 or 25 µM, an exogenous source of H2S). Both LC and Na2 S supplementation decreased intracellular ROS production and increased cellular PIP3 (phosphatidylinositol-3,4,5-trisphosphate) in HG-exposed cells. The effect of LC on PIP3 was prevented by propargylglycine, an inhibitor of cystathionine-γ-lyase (CSE) that catalyzes H2S formation from LC. Signal silencing studies with CSE siRNA also showed the inhibition of H2S formation and PIP3 upregulation in LC-supplemented CSE knockdown cells exposed to HG. This demonstrates that H2S plays a role in mediating the effect of LC on increased PIP3. Using the PI3K specific inhibitor LY294002, this study demonstrated that PI3K activation mediates the effect of LC and Na2S on PIP3 upregulation. Results showed that supplementation with LC and Na2S reduced NF-κB phosphorylation and the secretion of TNF-α, MCP-1, IL-8, IL-1ß, and IP-10. Treatment with LC (500 µM), Na2S (25 µM), and PIP3 (5 nM) increased the AMPK phosphorylation and PPARγ expression in cells exposed to HG. This study reports for the first time a novel molecular mechanism by which Na2S or LC supplementation can lower oxidative stress and various markers of vascular inflammation in diabetes.

D-saccharic acid 1,4-lactone protects diabetic rat kidney by ameliorating hyperglycemia-mediated oxidative stress and renal inflammatory cytokines via NF-κB and PKC signaling.

Increasing evidence suggests that oxidative stress is involved in the pathogenesis of diabetic nephropathy (DN) and this can be attenuated by antioxidants. D-Saccharic acid 1,4-lactone (DSL) is known for its detoxifying and antioxidant properties. Our early investigation showed that DSL can ameliorate alloxan (ALX) induced diabetes mellitus and oxidative stress in rats by inhibiting pancreatic ß-cell apoptosis. In the present study we, therefore, investigated the protective role of DSL against renal injury in ALX induced diabetic rats. ALX exposure (at a dose of 120 mg/kg body weight, i. p., once) elevated the blood glucose level, serum markers related to renal injury, the production of reactive oxygen species (ROS), and disturbed the intra-cellular antioxidant machineries. Oral administration of DSL (80 mg/kg body weight) restored all these alterations close to normal. In addition, DSL could also normalize the aldose reductase activity which was found to increase in the diabetic rats. Investigating the mechanism of its protective activity, we observed the activation of different isoforms of PKC along with the accumulation of matrix proteins like collagen and fibronectin. The diabetic rats also showed nuclear translocation of NF-κB and increase in the concentration of inflammatory cytokines in the renal tissue. The activation of mitochondria dependent apoptotic pathway was observed in the diabetic rat kidneys. However, treatment of diabetic rats with DSL counteracted all these changes. These findings, for the first time, demonstrated that DSL could ameliorate renal dysfunction in diabetic rats by suppressing the oxidative stress related signalling pathways.