Design, synthesis and biological evaluation of some tetrazole acetamide derivatives as novel non-carboxylic PTP1B inhibitors.

A series of ten N-(3-(1H-tetrazole-5-yl)phenyl)acetamide derivatives (NM-07 to NM-16) designed from a lead molecule identified previously in our laboratory were synthesized and evaluated for protein tyrosine phosphatase 1B (PTP1B) inhibitory activity. Among the synthesized molecules, NM-14, a 5-Cl substituted benzothiazole analogue elicited significant PTP1B inhibition with an IC50 of 1.88 µM against reference standard suramin (IC50 ≥ 10 µM). Furthermore, this molecule also showed good in vivo antidiabetic activity which was comparable to that of standard antidiabetic drugs metformin and glimepiride. Overall, the results of the study clearly reveal that the reported tetrazole derivatives especially NM-14 are valuable prototypes for the development of novel non-carboxylic inhibitors of PTP1B with antidiabetic potential.

Synthesis and biological evaluation of some N-(3-(1H-tetrazol-5-yl) phenyl)acetamide derivatives as novel non-carboxylic PTP1B inhibitors designed through bioisosteric modulation.

Described herein is the synthesis and biological evaluation of a series of non-carboxylic inhibitors of Protein Tyrosine Phosphatase 1B designed using bioisosteric replacement strategy. Six N-(3-(1H-tetrazol-5-yl)phenyl)acetamide derivatives designed employing the aforementioned strategy were synthesized and screened for PTP1B inhibitory activity. Among the synthesized compounds, compound NM-03 exhibited the most potent inhibitory activity with IC50 value of 4.48 µM. Docking studies with NM-03 revealed the key interactions with desired amino acids in the binding site of PTP1B. Furthermore, compound NM-03 also elicited good in vivo activity. Taken together, the results of this study establish N-(3-(1H-tetrazole-5-yl)phenyl)-2-(benzo[d]oxazol-2-ylthio)acetamide (NM-03) as a valuable lead molecule with great potential for PTP1B inhibitor development targeting diabetes.

Design, synthesis and anti-diabetic activity of triazolotriazine derivatives as dipeptidyl peptidase-4 (DPP-4) inhibitors.

Type 2 diabetes mellitus (T2DM) is one of the major global metabolic disorders characterized by insulin resistance and chronic hyperglycemia. Inhibition of the enzyme, dipeptidyl peptidase-4 (DPP-4) has been proved as successful and safe therapy for the treatment of T2DM since last decade. In order to design novel DPP-4 inhibitors, various in silico studies such as 3D-QSAR, pharmacophore modeling and virtual screening were performed and on the basis of the combined results of them, total 50 triazolo[5,1-c][1,2,4]triazine derivatives were designed and mapped on the best pharmacophore model. From this, best 25 derivatives were docked onto the active site of DPP-4 enzyme and in silico ADMET properties were also predicted. Finally, top 17 derivatives were synthesized and characterized using FT-IR, Mass, 1H NMR and 13C NMR spectroscopy. Purity of compounds was checked using HPLC. These derivatives were then evaluated for in vitro DPP-4 inhibition. The most promising compound 15q showed 28.05µM DPP-4 IC50 with 8-10-fold selectivity over DPP-8 and DPP-9 so selected for further in vivo anti-diabetic evaluation. During OGTT in normal C57BL/6J mice, compound 15q reduced blood glucose excursion in a dose-dependent manner. Chronic treatment for 28days with compound 15q improved the serum glucose levels in type 2 diabetic Sprague Dawley rats wherein diabetes was induced by high fat diet and low dose streptozotocin. This suggested that compound 15q is a moderately potent and selective hit molecule which can be further optimized structurally to increase the efficacy and overall pharmacological profile as DPP-4 inhibitor.

Protective effect of Tephrosia purpurea in diabetic cataract through aldose reductase inhibitory activity.

PURPOSE: Tephrosia purpurea (T. purpurea) has been reported to prevent cataract formation in senile cataract model as well as proven effective in STZ induced type 1 diabetes. Aldose reductase (AR) is a key enzyme in the intracellular polyol pathway responsible for the development of diabetic cataract. OBJECTIVE: To investigate the effects of T. purpurea in the light of inhibition of aldose reductase enzyme in polyol pathway. METHODS: We studied the effects of alcoholic extract and flavonoid fraction of T. purpurea in streptozotocin (STZ, 45mg/kg, i.v.)-induced type I diabetic cataract in rats. The animals were divided into five groups as control, control treated with alcoholic and flavonoid fraction, diabetic control and diabetic treated with alcoholic and flavonoid fraction. In-vitro aldose reductase inhibitory activity was also evaluated. Further, molecular docking study was performed with crystal structure of aldose reductase and its known chemical constituents of the plant. RESULTS: The IC50 value of alcoholic extract for aldose reductase inhibition was found to be 209.13µg/ml, and that of flavonoid fraction was found to be 46.73µg/ml. Administration of STZ produced significantly abnormal levels of serum glucose, serum insulin, soluble protein and antioxidants in the lens homogenate. Treatment with alcoholic extract and flavonoid fraction of T. purpurea were able to normalize these levels. Some of the active constituents of T. purpurea showed significant interactions with aldose reductase enzyme in molecular docking studies. CONCLUSIONS: Our data suggested that both the extracts might be helpful in delaying the development of diabetic cataract due to the presence of rutin and quercetin. This beneficial effect may be due to its significant inhibition of aldose reductase enzyme and anti-oxidant activity.

Preventive Effect of Tephrosia purpurea on Selenite-Induced Experimental Cataract.

PURPOSE: Recent investigations have shown that phytochemical antioxidants can scavenge free radicals and prevent various diseases like cataract. The objective of the present study was to assess the efficacy of the Tephrosia purpurea in preventing these changes in the lens of selenite-induced cataract models. MATERIALS AND METHODS: Cataract was induced by a single injection of sodium selenite (4 mg/kg, s.c.) to 9-day-old Sprague-Dawley rat pups. The treatment with different extracts of T. purpurea was started on 10th day and continued for 30 days in pups pretreated with sodium selenite. The animals were treated orally with either quercetin (1 mg/kg), flavonoid rich fraction (40 mg/kg) or alcohol extract (300 mg/kg) of T. purpurea. Cataract was visualized after 30 days. Encapsulated lenses were analyzed for reduced glutathione and malondialdehyde. Lenses were also analyzed for total protein, insoluble protein, total nitrite, calcium levels, protein sulfhydryl content as well as for the activities of superoxide dismutase and Ca(2+)-ATPase. RESULTS: Morphological examination of the rat lenses revealed normal transparent lens with minimal or partial nuclear opacity in control whereas dense opacity developed in rat lens treated with selenite. Both the extracts of T. purpurea produced reduction in nuclear opacity as well as improvement in the insoluble proteins, protein sulfhydryl, total nitrite, calcium levels and Ca(2+)-ATPase activity in lenses. The extracts decreased malondialdehyde levels but also prevented the loss of reduced glutathione levels. CONCLUSION: Our data suggests therapeutic potential of T. purpurea for the treatment of cataract.

Effect of flavonoid rich fraction of Tephrosiapurpurea (Linn.) Pers. on complications associated with streptozotocin-induced type I diabetes mellitus.

Globally, diabetes is a serious health issue affecting one in 11 adults and consumes 12% of global health expenditure. Prevalence of dyslipidemia in diabetes is not uncommon since decades. Further, patients with type II diabetes have 2-4 folds more risk for cardiovascular disease (CVD). Plants with antioxidant potential are known to have beneficial effects in diabetes and its complications: Natural compounds, flavonoids particularly, ameliorate hyperglycemia as well as CVD. Here, we evaluated common wasteland weed Tephrosia purpurea, used traditionally as folk medicine to treat many disorders including diabetes. We studied the effect of 8-wk treatment of flavonoid-rich fraction of T. purpurea (FFTp) (40 mg/kg/day/p.o.) on various biochemical, cardiovascular and lenticular parameters on streptozotocin (STZ) (45 mg/kg, i.v.) induced type I diabetic rats. STZ administration produced significant hyperglycemia, dyslipidemia, and altered cardiac biomarkers like lactate dehydrogenase, creatinine kinase and reduced antioxidants in lenticular tissues of rats. Treatment with FFTp significantly prevented STZ-induced hyperglycemia, dyslipidemia as well as cardiovascular markers. We observed decreased rate of pressure development (+dp/dt) and decay (-dp/dt) in STZ diabetic hearts which was prevented by FFTp. Further, the soluble protein levels and the antioxidants were also elevated in the diabetic rats by the treatment. In conclusion, our data suggest that FFTp produces beneficial effects on diabetes induced cardiovascular complications and cataract. Such beneficial actions may be attributed to the antioxidant property of flavonoids, quercetin or rutin, present in T. purpurea.

Effect of Aqueous Extract of Tephrosia purpurea on Cardiovascular Complications and Cataract Associated with Streptozotocin-induced Diabetes in Rats.

Tephrosia purpurea has been reported to possess antidiabetic activity, however, its effects on cardiovascular complications and cataract associated with diabetes have not been studied. The objective of the present study was to investigate the effects of aqueous extract of Tephrosia purpurea on cardiovascular complications and cataract associated with streptozotocin-induced diabetes in rats. Sprague Dawley rats of either sex were made diabetic with streptozotocin (45 mg/kg, i.v.). Treatment of aqueous extract of Tephrosia purpurea was given in the dose of 300 and 500 mg/kg/day, p.o for 8 weeks. Various hemodynamic (blood pressure, heart rate, +dp/dt, -dp/dt) and biochemical (serum glucose, cholesterol, triglycerides, creatinine, urea, lactate dehydrogenase and creatinine kinase) parameters were recorded after 8 weeks of the treatment. To evaluate cataract, various biochemical estimations were done in eye lens. Streptozotocin produced hyperglycemia; hypoinsulinemia; hyperlipidemia; increased blood pressure; increased creatinine, cardiac enzymes, reduction in heart rate and cardiac hypertrophy in rats and all these changes were prevented by the treatment with aqueous extract of Tephrosia purpurea in both the doses. Streptozotocin also produced decrease in soluble protein and reduced glutathione in lens of rats that was prevented by aqueous extract of Tephrosia purpurea. Our data suggest that aqueous extract of Tephrosia purpurea prevents not only the streptozotocin-induced metabolic abnormalities but also cardiovascular complications as well as reduce the risk of development of cataract.

Type 2 diabetes-induced cardiovascular complications: comparative evaluation of spironolactone, atenolol, metoprolol, ramipril and perindopril.

The present study was carried out to study the effect of spironolactone, atenolol, metoprolol, ramipril and perindopril on cardiovascular complications in neonatal model of diabetes in rats, induced by administering 90 mg/kg streptozotocin (STZ), i.p. in 2-day-old rats. Our data suggest that spironolactone, metoprolol and perindopril prevent not only the STZ-induced metabolic abnormalities but also cardiovascular complications as evident from the reduction in cholesterol, triglyceride and decrease in cardiac hypertrophy which are the initial symptoms of congestive heart failure. Metoprolol and perindopril appears to be beneficial agents as compared to atenolol and ramipril.

Investigation of the potential effects of metformin on atherothrombotic risk factors in hyperlipidemic rats.

The increased mortality rate due to atherothrombotic events and related complications has necessitated the search for new pharmacological agents. Hyperlipidemia, thrombosis and oxidative stress are the primary underlying concerns in the pathogenesis of atherosclerosis. Metformin, although proved to be beneficial in micro and macrovascular complications of diabetes mellitus, its effects on pure cardiovascular subjects are still debatable. Hence, the aim of the present study was to investigate the effects of metformin on atherothrombotic risk factors in experimental hyperlipidemic rats. Hyperlipidemia was induced by an intra-peritoneal injection of criton X-100 (25 mg/kg). Assessment of the effects of metformin (300 mg/kg/day, 400 mg/kg/day and 500 mg/kg/day) on lipid profile, coagulation time (activated partial thromboplastin time and prothrombin time), fibrinogen level, thrombosis, lipid peroxidation, antioxidant enzymes level, plasma fluorescent oxidation products and aortic nitrite level revealed an overall improvement in the lipid profile at the dose of 400 mg/kg along with a significant reduction in oxidative stress as compared to criton X-100 treated control. Activated partial thromboplastin and prothrombin times were prolonged at all doses, while plasma fibrinogen level remained unaffected. Metformin pre-treatment also reduced endothelial cell damage in ferrous chloride induced thrombosis in carotid arteries. Thus, the results indicate a potential protective effect of metformin on atherothrombotic risk factors, as evident from an improvement in lipid profile, reduction in oxidative stress and thrombotic events.

Angiogenic targets for potential disorders.

This review shall familiarize the readers with various fundamental aspects of angiogenesis. Angiogenesis is a feature of a limited number of physiological processes like wound healing, ovulation, development of the corpus luteum, embryogenesis, lactating breast, during immune response, and during Inflammation. It is driven by a cocktail of growth factors and pro-angiogenic cytokines and is tempered by an equally diverse group of inhibitors of neovascularization. The properties and biological functions of angiogenic growth factors such as VEGF, FGF-2, nitric oxide, MMP, angiopoietin, TGF-ß as well as various inhibitors such as angiostatin, endostatin, thrombospondin, canstatin, DII4, PEDF are discussed in this review with respect to their impact on angiogenic process. In recent years, it has become increasingly evident that excessive, insufficient, or abnormal angiogenesis contributes to the pathogenesis of many more disorders. A long list of disorders is characterized or caused by excessive or insufficient angiogenesis whereas several congenital or inherited diseases are also caused by abnormal vascular remodeling. It may be possible in the future to develop specific anti-angiogenic agents that offer a potential therapy for cancer and angiogenic diseases.

ß(3) Receptors: Role in Cardiometabolic Disorders.

Pharmacological and molecular approaches have shown that an atypical ß-adrenoceptor (AR), called ß(3)-AR, that is distinct from ß(1)-ARs and ß(2)-ARs, exists in some tissues in heterogeneous populations such as ß(3a)-ARs and ß(3b)-ARs. ß(3)-ARs belong to a superfamily of receptors linked to guanine nucleotide binding proteins (G proteins). The ß(3)-AR gene contains two introns whereas the ß(1)-AR and ß(2)-AR genes are intronless, leading to splice variants. ß(3)-ARs can couple to G(i) and G(s) and they are reported to be present in brown adipose tissue, vasculature, the heart, among other tissues. ß(3)-ARs cause vasodilation of microvessels in the islets of Langerhans and may participate in the pathogenesis of cardiac failure, during which modification of ß(1)-AR and ß(2)-AR expression occurs. The development of ß(3)-AR agonists has led to the elaboration of promising new drugs, including antiobesity and antidiabetic drugs. This article reviews the various pharmacological actions of ß(3)-ARs and their clinical implications for diabetes and cardiovascular diseases.

Therapeutic opportunities of small interfering RNA.

Formation of small interfering RNA (siRNA) occurs in two steps involving binding of the RNA nucleases to a large double-stranded RNA (dsRNA) and its cleavage into fragments called siRNA. In the second step, these siRNAs join a multinuclease complex, which degrades the homologous single-stranded mRNAs. The delivery of siRNA involves viral- and non-viral-mediated delivery systems; the approaches for chemical modifications have also been developed. It has various therapeutic applications for disorders like cardiovascular diseases, central nervous system (CNS) disorders, cancer, human immunodeficiency virus (HIV), hepatic disorders, etc. The present review gives an overview of the applications of siRNA and their potential for treating many hitherto untreatable diseases.

Getting into the brain: approaches to enhance brain drug delivery.

Being the most delicate organ of the body, the brain is protected against potentially toxic substances by the blood-brain barrier (BBB), which restricts the entry of most pharmaceuticals into the brain. The developmental process for new drugs for the treatment of CNS disorders has not kept pace with progress in molecular neurosciences because most of the new drugs discovered are unable to cross the BBB. The clinical failure of CNS drug delivery may be attributed largely to a lack of appropriate drug delivery systems. Localized and controlled delivery of drugs at their desired site of action is preferred because it reduces toxicity and increases treatment efficiency. The present review provides an insight into some of the recent advances made in the field of brain drug delivery.The various strategies that have been explored to increase drug delivery into the brain include (i) chemical delivery systems, such as lipid-mediated transport, the prodrug approach and the lock-in system; (ii) biological delivery systems, in which pharmaceuticals are re-engineered to cross the BBB via specific endogenous transporters localized within the brain capillary endothelium; (iii) disruption of the BBB, for example by modification of tight junctions, which causes a controlled and transient increase in the permeability of brain capillaries; (iv) the use of molecular Trojan horses, such as peptidomimetic monoclonal antibodies to transport large molecules (e.g. antibodies, recombinant proteins, nonviral gene medicines or RNA interference drugs) across the BBB; and (v) particulate drug carrier systems. Receptor-mediated transport systems exist for certain endogenous peptides, such as insulin and transferrin, enabling these molecules to cross the BBB in vivo.The use of polymers for local drug delivery has greatly expanded the spectrum of drugs available for the treatment of brain diseases, such as malignant tumours and Alzheimer's disease. In addition, various drug delivery systems (e.g. liposomes, microspheres, nanoparticles, nanogels and bionanocapsules) have been used to enhance drug delivery to the brain. Recently, microchips and biodegradable polymers have become important in brain tumour therapy.The intense search for alternative routes of drug delivery (e.g. intranasal drug delivery, convection-enhanced diffusion and intrathecal/intraventricular drug delivery systems) has been driven by the need to overcome the physiological barriers of the brain and to achieve high drug concentrations within the brain. For more than 30 years, considerable efforts have been made to enhance the delivery of therapeutic molecules across the vascular barriers of the CNS. The current challenge is to develop drug delivery strategies that will allow the passage of drug molecules through the BBB in a safe and effective manner.

Comparative evaluation of atenolol and metoprolol on cardiovascular complications associated with streptozotocin-induced diabetic rats.

Recently, various clinical studies have indicated that lipophilic beta-blockers reduce the coronary mortality in diabetic patients; however, systematic studies have not been reported. The objective of the present investigation was to compare the effects of chronic treatment with metoprolol and atenolol on cardiovascular complications in streptozotocin (STZ)-induced diabetic rats. Injection of STZ produced hyperglycemia, hypoinsulinemia, hyperlipidemia, increased blood pressure, cardiac hypertrophy, reduction in heart rate, and structural alterations in cardiac tissues. Metoprolol and atenolol effectively prevented the development of hypertension in diabetic rats. Metoprolol treatment produced a slight but significant reduction in serum glucose levels with elevation in serum insulin levels, while atenolol produced a slight increase in glucose levels but no effect on insulin levels. Moreover, neither metoprolol nor atenolol treatment reduced the elevated cholesterol levels in diabetic rats. Metoprolol treatment significantly prevented STZ-induced increase in triglyceride levels, but atenolol failed to produce this effect. Metoprolol exhibited a minimal improvement in STZ-induced bradycardia, whereas atenolol produced a further reduction in heart rate. Histological examination showed metoprolol treatment also prevented STZ-induced hypertrophy and some of the alterations in cardiomyocytes. In conclusion, our data suggest that metoprolol has some beneficial effects over atenolol with respect to cardiovascular complications associated with diabetes mellitus.