Net Das-Evcimen

In vivo treatment with stobadine prevents lipid peroxidation, protein glycation and calcium overload but does not ameliorate Ca2+ -ATPase activity in heart and liver of streptozotocin-diabetic rats: comparison with vitamin E.

Hyperglycemia leads to excess production of reactive oxygen species (ROS), lipid peroxidation and protein glycation that may impair cellular calcium homeostasis and results in calcium sequestration and dysfunction in diabetic tissues. Stobadine (ST) is a pyridoindole antioxidant has been postulated as a new cardio- and neuroprotectant. This study was undertaken to test the hypothesis that the treatment with ST inhibits calcium accumulation, reduces lipid peroxidation and protein glycation and can change Ca2+,Mg2+-ATPase activity in diabetic animals. The effects of vitamin E treatment were also evaluated and compared with the effects of combined treatment with ST. Diabetes was induced by streptozotocin (STZ, 55 mg/kg i.p.). Some of diabetic rats and their age-matched controls were treated orally with a low dose of ST (24.7 mg/kg/day), vitamin E (400-500 IU/kg/day) or ST plus vitamin E for 10 weeks. ST and vitamin E separately produced, in a similar degree, reduction in diabetes-induced hyperglycemia. Each antioxidant alone significantly lowered the levels of plasma lipid peroxidation, cardiac and hepatic protein glycation in diabetic rats but vitamin E treatment was found to be more effective than ST treatment alone. Diabetes-induced increase in plasma triacylglycerol levels was not significantly altered by vitamin E treatment but markedly reduced by ST alone. The treatment with each antioxidant completely prevented calcium accumulation in diabetic heart and liver. Microsomal Ca2+,Mg2+-ATPase activity significantly decreased in both tissues of untreated diabetic rats. ST alone significantly increased microsomal Ca2+,Mg2+-ATPase activity in the heart of normal rats. However, neither treatment with ST nor vitamin E alone, nor their combination did change cardiac Ca2+,Mg2+-ATPase activity in diabetic heart. In normal rats, neither antioxidant had a significant effect on hepatic Ca2+,Mg2+-ATPase activity. Hepatic Ca2+,Mg2+-ATPase activity of diabetic rats was not changed by single treatment with ST, while vitamin E alone completely prevented diabetes-induced inhibition in microsomal Ca2+,Mg2+-ATPase activity in liver. Combined treatment with ST and vitamin E provided more benefits in the reduction of hyperglycemia and lipid peroxidation in diabetic animals. This study describes potential mechanisms on cellular effects of ST in the presence of diabetes-induced hyperglycemia that may delay or inhibit the development of diabetic complications. The use of ST together with vitamin E can better control hyperglycemia-induced oxidative stress.

Synthesis and biological activity of some new flavonyl-2,4-thiazolidinediones

A new series of flavonyl-2,4-thiazolidinediones (Va-c, VIa-c) was prepared by Knoevenagel reaction. The synthesized compounds were tested for their ability to inhibit rat kidney aldose reductase (AR) and for their insulinotropic activities in INS-1 cells. Compound Vb was able to increase insulin release in the presence of 5.6mmol/l glucose. Compounds VIa-c displayed moderate to high AR inhibitory activity levels. Particularly, compound VIa showed the highest AR inhibitory activity (86.57%).

Synthesis and aldose reductase inhibitory activity of some new chromonyl-2,4-thiazolidinediones.

As it is known that still, there were no any confident ARIs on the market and they have several side effects, we need to approve new ARIs to reduce diabetic complications especially which have effect on the cataract formation. In this study, a new series of chromonyl-2,4-thiazolidinediones (Ia-e, IIa-e, IIIa-e) were prepared by Knoevenagel reaction with substituted 3-formylchromones (3a-e) and unsubstituted (1) or substituted 2,4-thiazolidinedione (2). The synthesized compounds were tested for their ability to inhibit rat kidney AR by an in vitro spectrophotometric assay. Compound IIIe showed the highest inhibitory activity (82.43+/-0.76%). Compounds Ia-e and IIIa-d also showed significant inhibitory activity (42.40+/-5.78, 52.71+/-3.31, 49.69+/-1.55, 50.80+/-3.62, 46.70+/-2.33, 49.44+/-4.53, 61.17+/-4.74, 68.58+/-2.05, 77.28+/-0.26%, respectively).

Preliminary evaluation of rat kidney aldose reductase inhibitory activity of 2-phenylindole derivatives: affiliation to antioxidant activity

Diabetic complications including nephropathy, neuropathy, and cataract are leading causes of end-stage renal diseases and neurological disorders. Aldose reductase (AR), the rate-limiting enzyme of the polyol pathway, catalyzes the reduction of glucose to sorbitol via NADPH. Excessive accumulation of intracellular sorbitol found in various tissues of diabetic animals and in cells cultured under high glucose conditions has been proposed to be an important factor for the pathogenesis of diabetic complications. Indole ring–containing AR inhibitors have received considerable attention as potential treatments for diabetic complications. However, these agents have not achieved worldwide use because of limited efficacy or unacceptable adverse effects. In this study, a series of 2-phenylindole derivatives were evaluated via an in vitro spectrophotometric assay for their ability to inhibit rat kidney AR. In addition, the antioxidant and AR inhibitory activities of the compounds under study were compared.

In vitro aldose reductase inhibitory activity of some flavonyl-2,4-thiazolidinediones

Aldose reductase (AR) is implicated to play a critical role in diabetes and cardiovascular complications because of the reaction it catalyzes. AR enzyme appears to be the key factor in the reduction of glucose to sorbitol. Synthesis and accumulation of sorbitol in cells due to AR activity is the main cause of diabetic complications, such as diabetic cataract, retinopathy, neuropathy and nephropathy. Aldose reductase inhibitors have been found to prevent sorbitol accumulation in tissues. Numerous compounds have been prepared in order to improve the pharmacological prophile of inhibition of aldose reductase enzyme. In this study, seventeen flavonyl-2,4-thiazolidinediones (flavonyl-2,4-TZD) (Ia–e, IIa–e and IIIa–g) were tested for their ability to inhibit rat kidney AR. Compound Ib showed the highest inhibitory activity (88.69 ± 1.46%) whereas Ia, IIa, IIIa, IIIb also showed significant inhibitory activity (49.26 ± 2.85, 67.29 ± 1.09, 71.11 ± 1.95, 64.86 ± 1.21%, respectively).

Role of protein kinase C in diabetic complications

Hyperglycemia is an important factor in the development of macrovascular and microvascular complications in all diabetic patients. Several hypotheses have been postulated to explain the adverse effect of hyperglycemia on the vasculature; and one of these hypotheses is the activation of specific isoforms of protein kinase C (PKC) by diabetes. In this review, we summarize the molecular mechanisms of PKC activation and its relationship to diabetic complications. PKC activity regulates vascular permeability, contractility, extracellular matrix synthesis, hormone receptor turnover and proliferation, cell growth, angiogenesis, cytokine activation and leukocyte adhesion. All of these properties are abnormal in diabetes and are correlated with increased diacylglycerol–PKC pathway and PKCα, β1/2 and δ isoforms activation in the retina, aorta, heart and renal glomeruli.

Screening and evaluation of rat kidney aldose reductase inhibitory activity of some pyridazine derivatives

Aldose reductase (AR) is an enzyme that catalyzes the conversion of glucose to sorbitol, which is in turn converted to fructose by sorbitol dehydrogenase. The increased glucose flux through this metabolic pathway has been linked to the development of diabetic complications such as neuropathy, nephropathy, retinopathy, and cataract. Inhibitors of AR thus seem to have the potential to prevent or treat diabetic complications. AR inhibitors belong to different chemical classes, one of which comprises pyridazinone analogues. At present, however, side effects and/or insufficient pharmacokinetic profiles have made most of the drug candidates undesirable. We evaluated a series of 2H-pyridazine-3-one and 6-chloropyridazine analogues via an in vitro spectrophotometric assay for their ability to inhibit rat kidney AR. The study showed that the introduction of a pyrazole ring on pyridazinone led to a marked decrease in AR inhibitory potency. Moreover, introduction of an acetic acid side chain on 2H-pyridazine-3-one and 6-chloropyridazine did not improve the AR inhibitory activity, which was an unexpected result. On the basis of preliminary AR inhibitory screening results on 2H-pyridazine-3-one and 6-chloropyridazine derivatives, we embarked on the synthesis of more derivatives to discover more active molecules.

Synthesis and aldose reductase inhibitory effect of some new hydrazinecarbothioamides and 4-thiazolidinones bearing imidazo[2,1-b]thiazole moiety

Objectives: To synthesize and characterize 2-[[6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl]-N-alkyl/arylhydrazinecarbothioamide and 3-alkyl/aryl-2-[((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)acetyl)hydrazono]-5-nonsubstituted/methyl-4-thiazolidinone derivatives and evaluate them for their aldose reductase (AR) inhibitory effect. Materials and Methods: 2-[[6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl]-N-alkyl/arylhydrazinecarbothioamides (3a-f) and 3-alkyl/aryl-2-[((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)acetyl)hydrazono]-5-nonsubstituted/methyl-4-thiazolidinones (4a-j) were synthesized from 2-[6-(4-bromophenyl)imidazo[2,1-b]thiazole-3-yl]acetohydrazide (2). Their structures were elucidated by elemental analyses and spectroscopic data. The synthesized compounds were tested for their ability to inhibit rat kidney AR. Results: Among the synthesized compounds, 2-[[6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl]-N-benzoylhydrazinecarbothioamide (3d) showed the best AR inhibitory activity. Conclusion: The findings of this study indicate that the different derivatives of the compounds in this study may be considered interesting candidates for future research.

Evaluation of rat kidney aldose reductase inhibitory activity of some N-acetyl dehydroalanine derivatives

Aldose reductase (AR) is an enzyme that catalyzes the conversion of glucose to sorbitol, which is in turn converted to fructose by sorbitol dehydrogenase. Increased AR activity has been implicated in the pathogenesis of diabetic complications such as neuropathy, nephropathy, retinopathy, and cataract. Inhibitors of AR thus seem to have the potential to prevent or treat diabetic complications. At present, however, side effects and/or insufficient pharmacokinetic profiles have made most of the drug candidates undesirable. In this study, the synthesis (l–o) and ARI activity of 15 N-acetyl dehydroalanine derivatives (a–o) are described. The synthesized compounds mainly contained aliphatic and aromatic side chains. The insertion of ethyl and chloro propyl side chains were shown to be more effective than the rest of the compounds. Between the synthesized compounds N-ethyl (b) and N-propylchloride (h) derivatives showed the best ARI activities.