Showing papers by "Pallu Reddanna published in 2007"

Alteration of mitochondrial membrane potential by Spirulina platensis C-phycocyanin induces apoptosis in the doxorubicinresistant human hepatocellular-carcinoma cell line HepG2.

Abstract: C-PC (C-phycocyanin) is a water-soluble biliprotein from the filamentous cyanobacterium Spirulina platensis with potent antioxidant, anti-inflammatory and anticancerous properties In the present study, the effect of C-PC was tested on the proliferation of doxorubicin-sensitive (S-HepG2) and -resistant (R-HepG2) HCC (hepatocellular carcinoma) cell lines These studies indicate a 50% decrease in the proliferation of S- and R-HepG2 cells treated with 40 and 50 microM C-PC for 24 h respectively C-PC also enhanced the sensitivity of R-HepG2 cells to doxorubicin R-HepG2 cells treated with C-PC showed typical apoptotic features such as membrane blebbing and DNA fragmentation Flow-cytometric analysis of R-HepG2 cells treated with 10, 25 and 50 microM C-PC for 24 h showed 188, 3972 and 6564% cells in sub-G(0)/G(1)-phase respectively Cytochrome c release, decrease in membrane potential, caspase 3 activation and PARP [poly(ADP-ribose) polymerase] cleavage were observed in C-PC-treated R-HepG2 cells These studies also showed down-regulation of the anti-apoptotic protein Bcl-2 and up-regulation of the pro-apoptotic Bax (Bcl2-associated X-protein) protein in the R-HepG2 cells treated with C-PC The present study thus demonstrates that C-PC induces apoptosis in R-HepG2 cells and its potential as an anti-HCC agent

Fulminant Hepatic Failure in Rats Induces Oxidative Stress Differentially in Cerebral Cortex, Cerebellum and Pons Medulla

Abstract: Hepatic Encephalopathy (HE) is one of the most common complications of acute liver diseases and is known to have profound influence on the brain. Most of the studies, available from the literature are pertaining to whole brain homogenates or mitochondria. Since brain is highly heterogeneous with functions localized in specific areas, the present study was aimed to assess the oxidative stress in different regions of brain-cerebral cortex, cerebellum and pons medulla during acute HE. Acute liver failure was induced in 3-month old adult male Wistar rats by intraperitoneal injection of thioacetamide (300 mg/kg body weight for two days), a well known hepatotoxin. Oxidative stress conditions were assessed by free radical production, lipid peroxidation, nitric oxide levels, GSH/GSSG ratio and antioxidant enzyme machinery in three distinct structures of rat brain-cerebral cortex, cerebellum and pons medulla. Results of the present study indicate a significant increase in malondialdehyde (MDA) levels, reactive oxygen species (ROS), total nitric oxide levels [(NO) estimated by measuring (nitrites + nitrates)] and a decrease in GSH/GSSG ratio in all the regions of brain. There was also a marked decrease in the activity of the antioxidant enzymes-glutathione peroxidase, glutathione reductase and catalase while the super oxide dismutase activity (SOD) increased. However, the present study also revealed that pons medulla and cerebral cortex were more susceptible to oxidative stress than cerebellum. The increased vulnerability to oxidative stress in pons medulla could be due to the increased NO levels and increased activity of SOD and decreased glutathione peroxidase and glutathione reductase activities. In summary, the present study revealed that oxidative stress prevails in different cerebral regions analyzed during thioacetamide-induced acute liver failure with more pronounced effects on pons medulla and cerebral cortex.

Computer aided drug design approaches to develop cyclooxygenase based novel anti-inflammatory and anti-cancer drugs.

Abstract: Cyclooxygenases (COXs), the enzymes involved in the formation of prostaglandins from polyunsaturated fatty acids such as arachidonic acid, exist in two forms--the constitutive COX-1 that is cytoprotective and responsible for the production of prostaglandins and COX-2 which is induced by cytokines, mitogens and endotoxins in inflammatory cells and responsible for the increased levels of prostaglandins during inflammation. As a result COX-2 has become the natural target for the development of anti-inflammatory and anti-cancer drugs. While the conventional NSAIDs with gastric side effects inhibit both COX-1 and COX-2, the newly developed drugs for inflammation with no gastric side effects selectively block the COX-2 enzyme. NSAIDs, nonselective non-aspirin NSAIDs and COX-2 selective inhibitors, are being widely used for various arthritis and pain syndromes. Selective inhibitors of COX-2, however, convey a small but definite risk of myocardial infarction and stroke; the extent of which varies depending on the COX-2 specificity. In view of the gastric side effects of conventional NSAIDs and the recent market withdrawal of rofecoxib and valdecoxib due to their adverse cardiovascular side effects there is need to develop alternative anti-inflammatory agents with reduced gastric and cardiovascular problems. The present study reviews various Computer Aided Drug Design (CADD) approaches to develop Cyclooxygenase based anti-inflammatory and anti-cancer drugs.

Calculation of relative binding affinities of fructose 1,6‐bisphosphatase mutants with adenosine monophosphate using free energy perturbation method

Abstract: The free energy perturbation (FEP) methodology is the most accurate means of estimating relative binding affinities between inhibitors and protein variants. In this article, the importance of hydrophobic and hydrophilic residues to the binding of adenosine monophosphate (AMP) to the fructose 1,6-bisphosphatase (FBPase), a target enzyme for type-II diabetes, was examined by FEP method. Five mutations were made to the FBPase enzyme with AMP inhibitor bound: 113Tyr → 113Phe, 31Thr → 31Ala, 31Thr → 31Ser, 177Met → 177Ala, and 30Leu → 30Phe. These mutations test the strength of hydrogen bonds and van der Waals interactions between the ligand and enzyme. The calculated relative free energies indicated that: 113Tyr and 31Thr play an important role, each via two hydrogen bonds affecting the binding affinity of inhibitor AMP to FBPase, and any changes in these hydrogen bonds due to mutations on the protein will have significant effect on the binding affinity of AMP to FBPase, consistent to experimental results. Also, the free energy calculations clearly show that the hydrophilic interactions are more important than the hydrophobic interactions of the binding pocket of FBPase. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007

Metabolism of arachidonic acid in sheep uterus: in vitro studies.

Abstract: Arachidonic acid (AA) metabolism in the non-pregnant sheep uterus was studied in vitro using conventional chromatographic and HPLC techniques. High expression of both lipoxygenase (LOX) as well as cyclooxygenase (COX) enzymes and their activities was found in the uterine tissues. On incubation of uterine enymes with AA, the LOX products formed were identified as 5-hydroperoxyeicosatetraenoic acid (5-HPETE), 12- and 15-hydroxyeicosatetraenoic acids (12- and 15-HETEs), based on their separation on TLC and HPLC. By employing differential salt precipitation techniques, the LOXs generating products 5-HPETE (5-LOX), 12-HETE and 15-HETE (12- and 15-dual LOX) were isolated. Based on their analysis on TLC, the COX products formed were identified as prostaglandins - PGF2alpha and prostacyclin derivative 6-keto PGF1alpha. The study forms the first report on the comprehensive analysis on the metabolism of AA in sheep uterus in vitro via the LOX and COX pathways.

Synthesis of [2-(3-Oxo-3,4-dihydro-2H-benzo [1,4]oxazin-6-carbonyl)-1H-indol-3-yl]acetic Acids as Potential COX-2 Inhibitors.

Abstract: The synthesis of potential COX-2 inhibitors by means of internal Michael addition of ortho toluenesulfonylaminophenyl acrylic acid methyl esters 5a-d with 6-(chloroacetyl)-2H-1,4-bezoxazin-4H-ones 6a-c followed by hydrolysis resulting in the formation of [2-(3-oxo-3,4-dihydro-2H-benzo[1,4]oxazin-6-carbonyl)-1H-indol-3-yl]acetic acids 1a-k are reported.

Synthesis of novel α-arylpropionic acids and their derivatives

Abstract: A series of 2-(6H-benzo[c]chromen-3-yl)propionic acids have been synthesized and evaluated for COX-2 inhibitor activity.

Synthesis of 2-aminophenyl-5-phenyl-4-[3-oxo-1,4-benzoxazin-6-yl] thiazoles as potential COX-2 inhibitors

Abstract: A series of 2-aminophenyl-5-phenyl-4-[3-oxo-1,4-benzoxazin-6-yl]thiazoles 5a-n have been prepared and evaluated for their COX-2 inhibition activity.

Synthesis of Methyl‐5‐[2‐arylamino‐4‐(3‐oxo‐1,4‐benzoxazin‐6‐yl)thiazole]acetates and 7H‐[3‐Aryl‐6‐(3‐oxo‐1,4‐benzoxazin‐6‐yl)‐s‐triazolo[3,4‐b] [1,3,4]thiadiazin‐7‐yl]acetates as Possible COX‐2‐Inhibitors.

Abstract: A series of methyl 5-[2-arylamino-4-(3-oxo-[1,4]benzoxazin-6-yl)thiazoleacetates 5a-h and 7H-[3-aryl-6-(3-oxo-[1,4]-benzox-azin-6-yl)-s-triazolo[3,4-b][1,3,4]thiadiazin-7-yl]acetates 6a-e have been synthesized and tested for their COX-2 inhibitor activity.