Pankaj K. Bagul

Attenuation of insulin resistance, metabolic syndrome and hepatic oxidative stress by resveratrol in fructose-fed rats

Metabolic syndrome and oxidative stress are common complications of type 2 diabetes mellitus. The present study was designed to determine whether resveratrol, a widely used nutritional supplement, can improve insulin sensitivity, metabolic complication as well as hepatic oxidative stress in fructose-fed rats. Male Sprague Dawley rats (180-200 g) were divided into four groups with 8 animals each. Fructose-fed insulin resistant group (Dia) animals were fed 65% fructose (Research diet, USA) for a period of 8 weeks, whereas control group (Con) animals were fed 65% cornstarch (Research Diet, USA). Resveratrol, 10 mg/kg/day (Dia+Resv) or metformin 300 mg/kg/day (Dia+Met) were administered orally to the 65% fructose-fed rats for 8 weeks. At the end of the feeding schedule, Dia group had insulin resistance along with increased blood glucose, triglyceride, uric acid and nitric oxide (NO) levels. Significant (p<0.05) increase in hepatic TBARS and conjugated dienes, and significant (p<0.05) decrease in hepatic SOD and vitamin C was observed in Dia group compared to Con group. Administration of metformin or resveratrol significantly (p<0.05) normalized all the altered metabolic parameters. However, a marked insulin sensitizing action was only observed in the Dia+Resv group. Similarly, while metformin administration failed to normalize the increased TBARS levels and decreased SOD activity, resveratrol showed a more promising effect of all oxidative stress parameters measured in the present study. Attenuation of hepatic oxidative stress in fructose-fed rat liver after resveratrol administration was associated with significant (p<0.05) increase in nuclear level of NRF2 compared with other groups. The present study demonstrates that resveratrol is more effective than metformin in improving insulin sensitivity, and attenuating metabolic syndrome and hepatic oxidative stress in fructose-fed rats.

Garlic improves insulin sensitivity and associated metabolic syndromes in fructose fed rats

BackgroundType 2 diabetes mellitus, characterized by peripheral insulin resistance, is a major lifestyle disorder of the 21st Century. Raw garlic homogenate has been reported to reduce plasma glucose levels in animal models of type 1 diabetes mellitus. However, no specific studies have been conducted to evaluate the effect of raw garlic on insulin resistance or type 2 diabetes mellitus. This study was designed to investigate the effect of raw garlic on fructose induced insulin resistance, associated metabolic syndrome and oxidative stress in diabetic rats.MethodsMale Sprague Dawley rats weighing 200-250 gm body weight were divided into 3 groups (n = 7 per group) and fed diet containing 65% cornstarch (Control group) and 65% fructose (Diabetic group) for 8 weeks. The third group (Dia+Garl group) was fed both 65% fructose and raw garlic homogenate (250 mg/kg/day) for 8 weeks. Whole garlic cloves were homogenized with water to make a fresh paste each day.ResultsAt the end of 8 weeks, serum glucose, insulin, triglyceride and uric acid levels, as well as insulin resistance, as measured by glucose tolerance test, were significantly (p < 0.01) increased in fructose fed rats (Diabetic group) when compared to the cornstarch fed (Control) rats. Administration of raw garlic to fructose fed rats (Dia+Garl group) significantly (p < 0.05) reduced serum glucose, insulin, triglyceride and uric acid levels, as well as insulin resistance when compared with fructose fed rats. Garlic also normalised the increased serum levels of nitric oxide (NO) and decreased levels of hydrogen sulphide (H2S) after fructose feeding. Although body weight gain and serum glycated haemoglobin levels of fructose fed rats (Diabetic group) were not significantly different from control rats, significant (p < 0.05) reduction of these parameters was observed in fructose fed rats after garlic administration (Dia+Garl group). Significant (p < 0.05) increase in TBARS and decrease in GSH was observed in diabetic liver. Catalase was not significantly affected in any of the groups. Administration of raw garlic homogenate normalised both hepatic TBARS and GSH levels.ConclusionsOur study demonstrates that raw garlic homogenate is effective in improving insulin sensitivity while attenuating metabolic syndrome and oxidative stress in fructose-fed rats.

Resveratrol ameliorates cardiac oxidative stress in diabetes through deacetylation of NFkB-p65 and histone 3.

Resveratrol, a phytoalexin, has recently gained attention for protective effects against metabolic and cardiac diseases. The beneficial effects of resveratrol have been linked to sirtuin-1 (SIRT-1) activation. However, little is known about the effect of resveratrol in cardiac complications associated with diabetes. Here, we have demonstrated that resveratrol ameliorates cardiac hypertrophy, electrocardiographic abnormalities and oxidative stress in the fructose-fed diabetic rat heart. Mechanistic studies revealed that fructose feeding to Sprague-Dawley rats over a period of 8 weeks leads to cardiac hypertrophy and increased oxidative stress through increased activity of NADPH oxidase (NOX) and reactive oxygen species production. We found increased activity of nuclear factor kappa B (NFkB) p-65 along with decreased SIRT-1 activity in the diabetic heart. Resveratrol activates SIRT-1, which deacetylates NFkB-p65 at lysine 310 and histone 3 (H3) at lysine 9 position. SIRT1 activation leads to decreased binding of NFkB-p65 to DNA and attenuated cardiac hypertrophy and oxidative stress through reduced transcription of NADPH oxidase subunits. In vitro analysis also revealed that SIRT-1 activation by resveratrol is associated with decreased NFkB-p65 activity and NOX transcription. Similarly, knockdown or inhibition of SIRT1 in H9C2 cells increased acetylation of NFkB-p65 K310 and H3K9. Overall, our data demonstrated that SIRT-1 activation by resveratrol leads to deacetylation of both NFkB-p65 and H3, thereby attenuating cardiac oxidative stress and complications in diabetes.

Synthesis and biological evaluation of new epalrestat analogues as aldose reductase inhibitors (ARIs).

Baylis-Hillman chemistry derived four series of new epalrestat analogues were synthesized. Three structural changes are introduced in these 39 new epalrestat analogues synthesized. All compounds were evaluated for their in vitro aldose reductase inhibitory (ALR) activity. Biological activity data indicates that compounds 6, 16, 19, 28 and 29 are potent and the activity is in the range of reference drug, epalrestat. Molecular modelling studies were performed to understand the binding interactions of these active molecules with the ALR protein. Molecular docking data indicates the key interactions of epalrestat were retained in some of the active compounds whereas some new interactions were noticed for other molecules. The modifications introduced on epalrestat have impact for developing a new-type of ALR inhibitor.

Synthesis and evaluation of novel 2-butyl-4-chloro-1-methylimidazole embedded chalcones and pyrazoles as angiotensin converting enzyme (ACE) inhibitors.

A series of novel 2-butyl-4-chloro-1-methylimidazole embedded aryl and heteroaryl derived chalcones and pyrazoles were synthesized and evaluated for their angiotensin converting enzyme (ACE) inhibitory activity. The condensation of 2-butyl-4-chloro-1-methylimidazole-5-carboxaldehyde with various aryl and heteroaryl methyl ketones in the presence of 10% aqueous NaOH in methanol proceeded efficiently to give the respective chalcones in very good yields. Further, the reaction of chalcones with hydrazine hydrate in acetic acid gave substituted pyrazole analogues. Screening all 36 new compounds using ACE inhibition assay, resulted chalcones with better ACE inhibitory activity compared to the respective pyrazole analogues. Among the chalcones 4a-r, three compounds, (E)-3-(2-butyl-4-chloro-1-methyl-1H-imidazol-5-yl)-1-(5-chlorothiophen-2-yl)prop-2-enone 4i, (E)-3-(2-butyl-4-chloro-1-methyl-1H-imidazol-5-yl)-1-(1H-pyrrol-2-yl)prop-2-enone 4l, (E)-3-(2-butyl-4-chloro-1-methyl-1H-imidazol-5-yl)-1-(dibenzo[b,d] thiophen-2-yl)prop-2-enone 4q were resulted as most active ACE inhibitors with IC(50) of 3.60 μM, 2.24 μM, and 2.68 μM, respectively.

Insulin resistance, oxidative stress and cardiovascular complications: role of sirtuins.

Cardiovascular disease (CVD) is one of the major lifestyle associated disorders and leading causes of death worldwide. The incidence of CVD in diabetic patients has increased up to 3 folds and it became the major risk for diabetes associated morbidity and mortality. Insulin resistance and oxidative stress both play a central role in the pathogenesis and progression of diabetes. The high prevalence of CVD among diabetic patients suggests the role of insulin resistance and oxidative stress in developing cardiovascular complications. Finding molecular mechanisms which could control both insulin resistance and oxidative stress would be more efficacious in improving the cardiovascular complications. Recent literatures show that an epigenetic mechanism could control or regulate the cardiovascular complications in diabetes. Sirtuins, a group of enzymes, modulate epigenetic changes by deacetylating histone and non-histone proteins. These enzymes are distributed in different cell organelles and are found to regulate different biological processes. Recent findings showed that sirtuins modulate different important proteins related to insulin signaling pathway and oxidative stress. This review summarizes how sirtuins could affect the insulin resistance and oxidative stress pathways in cardiovascular system and thus attenuate the cardiovascular complications. Understanding the role of sirtuins in insulin resistance and oxidative stress will increase the prospects for controlling or preventing cardiovascular complications in the future.

Hyperglycaemia Enhances Nitric Oxide Production in Diabetes: A Study from South Indian Patients

Background We have previously reported that increased glucose levels were associated with higher serum nitric oxide (NO) levels in fructose-fed insulin resistant rats. However, the relationship between hyperglycemia and serum NO level was not clear. Therefore, the present study was designed to find the association between hyperglycemia and serum NO levels in Type 2 diabetic (T2DM) patients and T2DM with cardiovascular complication. Methods Endothelial cells (HUVEC) were treated with of D-glucose (10-100mM), and NO levels and NOS gene expression was measured. Hyperglycaemia was induced in Sprague-Dawley rats, and serum NO levels were measured after 8 weeks. For clinical evaluation, five groups of patients were recruited: Control (CT, n=48), Type 2 diabetes (T2DM, n=26), T2DM with hypertension (DMHT, n=46), Coronary artery diseases (CAD, n=29) and T2DM with coronary artery diseases (DMCD, n=38). NO (nitrite + nitrate) levels were measured from human serum. Results We found a significant (p<0.05) and dose-dependent increase in NO levels in HUVEC cells after 4 hours of high glucose exposure. eNOS and iNOS gene expression was increased in HUVEC cells after different concentrations and time periods of glucose treatment. We also observed significant (149.1±25μM, p<0.01) increase in serum NO levels in hyperglycaemic rats compared to control (76.6±13.2μM). Serum NO level was significantly higher in T2DM (111.8 μM (81.7-122.4), p<0.001) and DMCD patients ((129.4 μM (121.2-143.5), p <0.001) but not in CAD patients (76.4 μM (70.5-87)), as compared to control (68.2 μM (56.4-82.3)). We found significantly lower NO levels (83.5 μM (60.5-122.9)) in subjects suffering from diabetes since more than 5 years, compared to subjects (115.3 μM (75.2-127.1), p<0.001) with less than 5 years. Conclusion In conclusion, high NO levels were observed in South Indian diabetic patients. Higher glucose levels in serum might be responsible for activation of endothelial cells to enhance NO levels.

Effect of resveratrol on sirtuins expression and cardiac complications in diabetes.

Sirtuins are the protein deacetylases, which are linked to metabolic diseases and aging. There are seven sirtuins present in cell, whose regulation in diabetic heart is yet to be explored. Resveratrol is a well-known activator of SIRT-1, but its effect on other sirtuins is not yet clear. In the present study, we focused to find out the expression and regulation of all sirtuins in diabetic heart with the effect of resveratrol administration on them. We have induced T1DM rat model using steptozotocin and T2DM rat model by feeding high fructose diet for a period of eight weeks and analyzed the myocardial changes. Resveratrol was administrated to both the models simultaneously. Increased oxidative stress and cardiac phenotype alterations shows the induction of cardiac abnormalities in both models. We have observed decreased SIRT-1 and increased SIRT-3 activity in the T2DM rat heart. Moreover, in case of T1DM, gene and protein expression of all sirtuins was down, except SIRT-2 whose protein levels were increased. Administration of resveratrol prevented the alteration in SIRT-1 in T2DM and SIRT-1, 2, 3 and SIRT-5 in T1DM rat heart. Altered level of protein acetylation was observed corresponding to the changes in sirtuins. In conclusion, sirtuins are perturbed in both types of diabetic heart and can be considered as druggable target for therapeutic intervention.

Garlic activates SIRT-3 to prevent cardiac oxidative stress and mitochondrial dysfunction in diabetes

BACKGROUND Cardiac complications are major contributor in the mortality of diabetic people. Mitochondrial dysfunctioning is a crucial contributor for the cardiac complications in diabetes, and SIRT-3 remains the major mitochondrial deacetylase. We hypothesized whether garlic has any role on SIRT-3 to prevent mitochondrial dysfunction in diabetic heart. METHODS Rats with developed hyperglycemia after STZ injection were divided into two groups; diabetic (Dia) and diabetic+garlic (Dia+Garl). Garlic was administered at a dose of 250mg/kg/day, orally for four weeks. An additional group was maintained to evaluate the effect of raw garlic administration on control rat heart. RESULT We have observed altered functioning of cardiac mitochondrial enzymes involved in metabolic pathways, and increased levels of cardiac ROS with decreased activity of catalase and SOD in diabetic rats. Cardiac mRNA expression of TFAM, PGC-1α, and CO1 was also altered in diabetes. In addition, reduced levels of electron transport chain complexes that observed in Dia group were normalized with garlic administration. This indicates the presence of increased oxidative stress with mitochondrial dysfunctioning in diabetic heart. We have observed reduced activity of SIRT3 and increased acetylation of MnSOD. Silencing SIRT-3 in cells also revealed the same. However, administration of garlic improved the SIRT-3 and MnSOD activity, by deacetylating MnSOD. Increased SOD activity was correlated with reduced levels of ROS in garlic-administered rat hearts. CONCLUSION Collectively, our results provide an insight into garlics protection to T1DM heart through activation of SIRT3-MnSOD pathway.

Design and green synthesis of 2-(diarylalkyl)aminobenzothiazole derivatives and their dual activities as angiotensin converting enzyme inhibitors and calcium channel blockers.

A series of novel 2-(diarylalkyl)aminobenzothiazoles were designed based on commercial synthetic calcium channel blockers (CCBs) and angiotensin converting enzyme (ACE) inhibitors. Which are further modified based on the natural products which are angiotensin converting enzyme (ACE) inhibitors. Completely green protocol was developed for their synthesis. As they are initially designed based on CCBs, they were screened for their ACE inhibition property believing that almost all the compounds will be CCBs. Out of 42 compounds two lead molecules were identified as ACE inhibitors, which were further screened for CCB. As expected both were identified as CCBs with different selectivity over ACE inhibition. Their selectivity over ACE and CCB can be used to treat resistant hypertension.