Mukul R. Jain

Melatonin protects against lipid‐induced mitochondrial dysfunction in hepatocytes and inhibits stellate cell activation during hepatic fibrosis in mice

Lipid generates reactive oxygen species (ROS) in consequence to mitochondrial fission followed by inflammation in propagating hepatic fibrosis. The interaction of SIRT1/Mitofusin2 is critical for maintaining mitochondrial integrity and functioning, which is disrupted upon excess lipid infiltration during the progression of steatohepatitis. The complex interplay between hepatic stellate cells and steatotic hepatocytes is critically regulated by extracellular factors including increased circulating free fatty acids during fibrogenesis. Melatonin, a potent antioxidant, protects against lipid‐mediated mitochondrial ROS generation. Lipotoxicity induces disruption of SIRT1 and Mitofusin2 interaction leading to mitochondrial morphological disintegration in hepatocytes. Further, fragmented mitochondria leads to mitochondrial permeability transition pore opening, cell cycle arrest and apoptosis and melatonin protects against all these lipotoxicity‐mediated dysfunctions. These impaired mitochondrial dynamics also enhances the cellular glycolytic flux and reduces mitochondrial oxygen consumption rate that potentiates ROS production. High glycolytic flux generates metabolically unfavorable milieu in hepatocytes leading to inflammation, which is abrogated by melatonin. The melatonin‐mediated protection against mitochondrial dysfunction was also observed in high‐fat diet (HFD)‐fed mice through restoration of enzymatic activities associated with respiratory chain and TCA cycle. Subsequently, melatonin reduces hepatic fat deposition and inflammation in HFD‐fed mice. Thus, melatonin disrupts the interaction between steatotic hepatocyte and stellate cells, leading to the activation of the latter to abrogate collagen deposition. Altogether, the results of the current study document that the pharmacological intervention with low dose of melatonin could abrogate lipotoxicity‐mediated hepatic stellate cell activation and prevent the fibrosis progression.

Beneficial effects of carbon monoxide-releasing molecule-2 (CORM-2) on acute doxorubicin cardiotoxicity in mice: Role of oxidative stress and apoptosis

Doxorubicin (DXR) has been used in variety of human malignancies for decades. Despite its efficacy in cancer, clinical usage is limited because of its cardiotoxicity, which has been associated with oxidative stress and apoptosis. Carbon monoxide-releasing molecules (CORMs) have been shown to reduce the oxidative damage and apoptosis. The present study investigated the effects of CORM-2, a fast CO-releaser, against DXR-induced cardiotoxicity in mice using biochemical, histopathological and gene expression approaches. CORM-2 (3, 10 and 30 mg/kg/day) was administered intraperitoneally (i.p.) for 10 days and terminated the study on day 11. DXR (20 mg/kg, i.p.) was injected before 72 h of termination. Mice treated with DXR showed cardiotoxicity as evidenced by elevation of serum creatine kinase (CK) and lactate dehydrogenase (LDH), tissue malondialdehyde (MDA), caspase-3 and decrease the level of total antioxidant status (TAS) in heart tissues. Pre- and post-treatment with CORM-2 (30 mg/kg, i.p.) elicited significant improvement in CK, LDH, MDA, caspase-3 and TAS levels. Histopathological studies showed that cardiac damage with DXR has been reversed with CORM-2+DXR treatment. There was dramatic decrease in hematological count in DXR-treated mice, which has been improved with CORM-2. Furthermore, there was also elevation of mRNA expression of heme oxygenase-1, hypoxia inducible factor-1 alpha, vascular endothelial growth factor and decrease in inducible-nitric oxide synthase expression upon treatment with CORM-2 that might be linked to cardioprotection. These data suggest that CORM-2 treatment provides cardioprotection against acute doxorubicin-induced cardiotoxicity in mice and this effect may be attributed to CORM-2-mediated antioxidant and anti-apoptotic properties.

Solvent free synthesis of 1,5-disubstituted tetrazoles derived from Baylis Hillman acetates as potential TNF-α inhibitors

Solvent free multicomponent reaction of Baylis Hillman acetate, TMS azide and arylnitrile to produce 1,5-disubstituted tetrazole is described. Some of these tetrazoles are found to be potential TNF-alpha inhibitors.

Effect of saponins from Helicteres isora on lipid and glucose metabolism regulating genes expression

ETHNOPHARMACOLOGICAL RELEVANCEnWe characterized saponins as active constituents from traditionally used antidiabetic plant Helicteres isora.nnnAIM OF THE STUDYnTo evaluate the changes in the gene expression of the glucose and lipid metabolism regulating genes in C57BL/KsJ-db/db mice.nnnMATERIALS AND METHODSnC57BL/KsJ-db/db mice were divided into four different groups; one diabetic control, the mice in other three groups were treated with methanol extract (100 mg/kg), saponins (100 mg/kg) and pioglitazone (30 mg/kg) for 14 days. After completion of the treatment period biochemical parameters and the expression levels of adipsin, adiponectin, glucose transporter 4 (Glut4), peroxisome proliferator activated receptor gamma (PPARgamma), fatty acid binding protein 4 (FABP4), lipoprotein lipase (LPL) in adipose tissue and for liver RNA samples glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK), glucose transporter 2 (Glut2) and acyl-co-enzyme A oxidase (ACOX) were determined by quantitative real time PCR and angiopoeitin like 3 (ANGPTL3), angiopoeitin like 4 (ANGPTL4) and peroxisome proliferator activated receptor alpha (PPARalpha) by semiquantitative reverse transcription PCR.nnnRESULTSnTreatment caused a significant reduction in the serum lipid and glucose levels and increased the expression of adipsin, PPARgamma and Glut4 while reduced expression of FABP4 and G6Pase, whereas there was no effect on the expression levels of adiponectin, LPL, PEPCK, ACOX, Glut2, ANGPTL3, ANGPTL4 and PPARalpha.nnnCONCLUSIONSnSaponins are beneficial for improving hyperlipidemia and hyperglycemia by increasing the gene expression of adipsin, Glut4 and PPARgamma and reducing the gene expression of the enzyme G6Pase and FABP4 in C57BL/KsJ-db/db mice.

Cardioprotective effect with carbon monoxide releasing molecule-2 (CORM-2) in isolated perfused rat heart: Role of coronary endothelium and underlying mechanism.

Although the cardioprotective role of carbon monoxide (CO) has been studied against myocardial ischemia-reperfusion (I/R) injury, the role of coronary endothelium and underlying mechanism in carbon monoxide-induced cardioprotection is not well understood in isolated heart. The present study was designed to determine the role of coronary endothelium in CORM-2-mediated cardioprotection during I/R injury in isolated rat heart. Preconditioning with 30microM/l and 50microM/l of CORM-2 for 10min markedly reduced lactate dehydrogenase (LDH) and creatinin kinase (CK) levels in coronary effluent after global ischemia. There was also a significant improvement in coronary flow rate, heart rate, cardiodynamic parameters and marked attenuation in infarct size. However, protective effect was abolished when hearts were pretreated with 100microM CORM-2. We observed that pretreatment with L-NAME (100microM/l), a nitric oxide synthase (NOS) inhibitor did not affect protection by CORM-2 (50microM/l). On the other hand pretreatment with Triton X-100 (0.05% for 20s) to denude endothelium before CORM-2 treatment followed by I/R injury showed similar cardioprotection. Moreover, pretreatment with K(ATP) channel inhibitor, glibenclamide almost completely reversed the cardioprotective effect of CORM-2 in endothelium-denuded hearts. These results indicate that cardioprotection by CORM-2 is highly concentration-dependent, independent of coronary endothelium and cardioprotective effect might be attributed to the activation of K(ATP) channel present on vascular smooth muscle cell (VSMC).

Synthesis and structure-activity relationship of potent, selective and orally active anthranilamide-based factor Xa inhibitors: application of weakly basic sulfoximine group as novel S4 binding element.

A novel series of potent and efficacious factor Xa inhibitors which possesses sulfoximine moiety as novel S4 binding element in anthranilamide chemotype has been identified. Lead optimization at this novel P4 group led to many potent factor Xa inhibitors with excellent anticoagulant activity in human plasma. Selected compounds were dosed orally in rats and checked for their ex vivo prothrombin time prolonging activity, which resulted in identification of compound 5-chloro-N-(5-chloropyridin-2-yl)-2-(4-(N-(2-(diethylamino)acetyl)-S-methylsulfonimidoyl)benzamido)benzamide (18f). The detailed pharmacokinetic evaluation and subsequent metabolism study of 18f suggested the presence of an active metabolite. The compound 18f and its active metabolite 18b demonstrated excellent in vivo efficacy in both arterial and venous thrombosis model in rats and were found to be highly selective against related serine proteases. Based on this promising profile, compound 18f was selected for further evaluation.

Inhibition of microsomal triglyceride transfer protein improves insulin sensitivity and reduces atherogenic risk in Zucker fatty rats.

1.u2002Insulin‐resistant states are commonly associated with a significantly higher risk of atherosclerosis. Insulin resistance has also been correlated with enhanced very low‐density lipoprotein (VLDL) production, which is exacerbated by increased intestinal lipid synthesis and insulin‐stimulated de novo lipogenesis. Microsomal triglyceride transfer protein (MTP) catalyses the critical step in the synthesis and secretion of VLDL and chylomicrons. The purpose of the present study was to test the hypothesis that chronic inhibition of MTP with a small molecule inhibitor would improve insulin sensitivity and reduce atherogenic risk in a genetic model of diabetic dyslipidaemia.

Oxazolidinone Antibacterials and Our Experience

The Oxazolidinones are a promising novel chemical synthetic class of antibiotics identified in the last two dec- ades and have been subjected to intensive discovery efforts. They possess impressive antibacterial activity against Gram- positive pathogens. Oxazolidinones act through a unique mechanism of inhibitory bacterial protein biosynthesis. Linezolid (Zyvox TM ) has been the only drug of oxazolidinone class to reach the market after USFDA approval. Here we review our efforts directed to the discovery of novel oxazolidinone antibacterials evolved through structure-activity relationship (SAR) and an overview of contemporary on going efforts.

Retinol-binding protein 4: a possible role in cardiovascular complications

BACKGROUND AND PURPOSE Retinol‐binding protein 4 (RBP4) is an adipocyte‐secreted hormone proposed to link obesity with insulin resistance. However, the role of RBP4 in cardiovascular complications is yet to be fully understood. The present study is aimed to decipher the association between RBP4 with pro‐inflammatory cytokines and low‐density lipoprotein (LDL) cholesterol in diet‐induced obese and hyperlipidaemic mice. To understand the correlation, rimonabant, an anti‐obesity drug, has been used to relieve the atherosclerotic predisposition.

Emerging Therapies for Dyslipidemia: Known Knowns and Known Unknowns of MTP Inhibitors

Last decade had witnessed enormous efforts to develop therapies to treat one or more components of metabolic syndrome, a cluster of diseases including diabetes, obesity and dyslipidemia. Several newer targets are identified and evaluated to treat these metabolic disorders. Microsomal triglyceride transfer protein (MTP) has been identified as one of the promising target for the treatment of dyslipidemia. MTP plays crucial role in the assembly of triglyceride rich chylomicrones in enterocytes and VLDL in hepatocytes and several lines of evidence suggested that MTP inhibitors can be instrumental in combating familial hypercholesterolemia. Several first generation compounds are currently being evaluated in clinic and fatty liver is found to be the main adverse effect of these agents. Recently development of enterocyte specific inhibitor of MTP is emphasized in order to deal with fatty liver issue. In this review, we have dealt with important mechanistic aspects of MTP inhibition, patent scenario and clinical trial outcomes and some of the recent patents related to newly discover chemical scaffolds.