Synthesis and antihyperglycemic activity profiles of novel thiazolidinedione derivatives

A number of thiazolidine-2,4-diones derivatives having carboxylic ester appendage at N-3 were synthesized and their antihyperglycemic activity was evaluated. Many of these derivatives as well as their corresponding carboxylic acid showed significant improvement on post-prandial hyperglycemia in normal rats, in contrast to their poor agonist activity at PPARgamma.     

Simultaneous quantitation of fatty acids,sterols and bile acids in human stool by capillary gas-liquid chromatography

A simple method for the simultaneous gas-liquid chromatographic quantitation of fatty acids, sterols and bile acids from human fecal samples is described. The various compounds are directly converted into the n-butyl ester-trimethylsilyl ether derivatives, without prior isolation from the stool. Under these conditions, fecal bile acid derivatives are well resolved from each other and from those of fecal fatty acids and sterols without overlaps. The method was found to be reproducible and recoveries were similar to those obtained after exhaustive solvent extraction of fecal sterols, fatty acids and bile acids. Optimum derivatization conditions that allowed maximum recovery of fecal components with minimal destruction and application of the method for simultaneous bile acid, fatty acid and sterol analysis in human stool are described.     

Brassinosteroid-Mediated Stress Responses

Brassinosteroids (BRs) are a group of naturally occurring plant steroidal compounds with wide-ranging biological activity that offer the unique possibility of increasing crop yields through both changing plant metabolism and protecting plants from environmental stresses. In recent years, genetic and biochemical studies have established an essential role for BRs in plant development, and on this basis BRs have been given the stature of a phytohormone. A remarkable feature of BRs is their potential to increase resistance in plants to a wide spectrum of stresses, such as low and high temperatures, drought, high salt, and pathogen attack. Despite this, only a few studies aimed at understanding the mechanism by which BRs promote stress resistance have been undertaken. Studies of the BR signaling pathway and BR gene-regulating properties indicate that there is cross-talk between BRs and other hormones, including those with established roles in plant defense responses such as abscisic acid, jasmonic acid, and ethylene. Recent studies aimed at understanding how BRs modulate stress responses suggest that complex molecular changes underlie BR-induced stress tolerance in plants. Analyses of these changes should generate exciting results in the future and clarify whether the ability of BRs to increase plant resistance to a range of stresses lies in the complex interactions of BRs with other hormones. Future studies should also elucidate if BRI1, an essential component of the BR receptor, directly participates in stress response signaling through interactions with ligands and proteins involved in plant defense responses.     

Thermophilic bacteria that tolerate a wide temperature and pH range colonize the Soldhar (95 °C) and Ringigad (80 °C) hot springs of Uttarakhand,India

Twenty-eight bacterial cultures, isolated from hot springs in Uttarakhand, were characterized with particular reference to their wide temperature and pH tolerance and production of enzymes in the thermophilic range. All the bacterial isolates were observed as Gram-positive or variable rods in varied arrangement. Bacterial isolates exhibited tolerance to a wide temperature range (20–80 °C), from mesophilic (+11° to +45 °C) to thermophilic (+46 ° to +75 °C); few almost reached the hyperthermophilic range (+76 °C). The isolates also tolerated a wide pH range (4–14) and moderate salt concentration. The optimum growth of the bacterial isolates was observed at 55 °C and 7 pH. Out of 28 isolates, 25 produced lipase, 25 amylase, 24 cellulase, 22 protease and 13 xylanase at 55 and 65 °C. Tolerance to a wide temperature and pH range and the production of enzymes in a thermophilic temperature range can be considered as indicators of ecological competence of these bacterial isolates for colonizing the high temperature environment. On the basis of 16S rDNA similarity, 20 bacterial isolates belonged to Bacillus licheniformis, five to Paenibacillus ehimensis and one each to Bacillus sonorensis, B. tequilensis, and Staphylococcus epidermidis. Besides variation in phenotypic characters, strains of B. licheniformis and P. ehimensis showed varying 16S rDNA similarity between 97–99 % and 95–99 %, respectively. Consideration of temperature preferences in classifying microorganisms on the basis of their minimum, maximum, and optimum growth requirements is also discussed. The study has ecological relevance in the context of colonization of high temperature environments by thermophilic bacteria.     

Elicitation as yield enhancement strategy for glycyrrhizin production by cell cultures of <Emphasis Type="Italic">Abrus precatorius</Emphasis> Linn.

Glycyrrhizin is an important phytoconstituent of licorice which is widely used in the pharmaceutical and food industry. As the roots and leaves of Abrus precatorius also contain glycyrrhizin, it can be used as an alternative source of glycyrrhizin. In spite of extensive research work undertaken with cultures of Glycyrrhiza glabra, the glycyrrhizin production remains elusive. Successful production of glycyrrhizin in cell cultures of A. precatorius is being reported for the first time in our study. Cell cultures of A. precatorius L. were treated with the elicitors prepared from the fungi (Aspergillus niger and Rhizopus stolonifer), yeast extract, salicylic acid, ascorbic acid, and eugenol to induce and enhance the synthesis of glycyrrhizin. In the present study, an integrated yield enhancement strategy, developed by the addition of selected elicitor (A. niger and ascorbic acid) at optimized concentrations, resulted in 24.6 g/l dry cell weight biomass and 53.62 mg/l glycyrrhizin, which was 5.22 times higher in productivity in comparison to control cultures.     

Efficient shoot regeneration from internodal explants of Populus angustifolia, Populus balsamifera and Populus deltoids

In the present study, interactions between the duration of treatment with auxin and different cytokinins and their effect on shoot regeneration were evaluated with the aim to establish a rapid and efficient in vitro regeneration method applicable to a variety of Populus species. Three different species, Populus angustifolia, P. balsamifera, and P. deltoids, were chosen for that purpose. We were successful in regenerating plantlets from stem and petiole explants from all three chosen species using a four-step simple procedure. The first step was callus induction when the explants were exposed to an auxin-rich medium for 0-20 days. During the second step, they were transferred onto a cytokinin-rich medium for shoot bud induction. In the third step, the shoots regenerated were transferred onto a medium with reduced levels of cytokinins to promote shoot proliferation and elongation; finally, in the fourth step, the shoots were rooted and acclimated. A short period (6-10 days) of time of exposure to auxin was sufficient for shoot regeneration. A culture time longer than ten days in callus induction medium drastically reduced the efficiency of shoot regeneration. Besides, cytokinin type and concentration also affected the frequency of shoot induction. A 0.2 mg/l concentration of 2,4-D for callus induction followed by 0.02 mg/l of Thidiazuron for shoot formation proved to be the best treatment for adventitious shoot bud multiplication, generating a maximum of 10-13 shoots of P. balsamifera and P. angustifolia in ten weeks. In contrast, for P. deltoids, a combination of 1.1mg/l 2,4-D, 1.0mg/l NAA, 0.1mg/l zeatin for callus induction followed by a combination of 1mg/l zeatin plus 1.0mg/l BA for shoot bud induction was found to be the most effective, generating on average 15 shoots over a period of ten weeks.     

Inhibition of neuronal apoptosis by the cyclin-dependent kinase inhibitor GW8510: identification of 3' substituted indolones as a scaffold for the development of neuroprotective drugs

Increasing evidence suggests that neuronal apoptosis is triggered by the inappropriate activation of cyclin-dependent kinases leading to an abortive re-entry of neurons into the cell cycle. Pharmacological inhibitors of cell-cycle progression may therefore have value in the treatment of neurodegenerative diseases in humans. GW8510 is a 3' substituted indolone that was developed recently as an inhibitor of cyclin-dependent kinase 2 (CDK2). We found that GW8510 inhibits the death of cerebellar granule neurons caused by switching them from high potassium (HK) medium to low potassium (LK) medium. Although GW8510 inhibits CDK2 and other CDKs when tested in in vitro biochemical assays, when used on cultured neurons it only inhibits CDK5, a cytoplasmic CDK that is not associated with cell-cycle progression. Treatment of cultured HEK293T cells with GW8510 does not inhibit cell-cycle progression, consistent with its inability to inhibit mitotic CDKs in intact cells. Neuroprotection by GW8510 is independent of Akt and MEK-ERK signaling. Furthermore, GW8510 does not block the LK-induced activation of Gsk3beta and, while inhibiting c-jun phosphorylation, does not inhibit the increase in c-jun expression observed in apoptotic neurons. We also examined the effectiveness of other 3' substituted indolone compounds to protect against neuronal apoptosis. We found that like GW8510, the VEGF Receptor 2 Kinase Inhibitors [3-(1H-pyrrol-2-ylmethylene)-1,3-dihydroindol-2-one], {(Z)-3-[2,4-Dimethyl-3-(ethoxycarbonyl)pyrrol-5-yl)methylidenyl]indol-2-one} and [(Z)-5-Bromo-3-(4,5,6,6-tetrahydro-1H-indol-2-ylmethylene)-1,3-dihydroindol-2-one], the Src family kinase inhibitor SU6656 and a commercially available inactive structural analog of an RNA-dependent protein kinase inhibitor 5-Chloro-3-(3,5-dichloro-4-hydroxybenzylidene)-1,3-dihydro-indol-2-one, are all neuroprotective when tested on LK-treated neurons. Along with our recent identification of the c-Raf inhibitor GW5074 (also a 3' substituted indolone) as a neuroprotective compound, our findings identify the 3' substituted indolone as a core structure for the designing of neuroprotective drugs that may be used to treat neurodegenerative diseases in humans.     

Amperometric microbial biosensor for p-nitrophenol using Moraxella sp.-modified carbon paste electrode

An amperometric microbial biosensor for highly specific, sensitive and rapid quantitative determination of p-nitrophenol was developed. The biosensor takes advantage of the ability of Moraxella sp. to specifically degrade p-nitrophenol to hydroquinone, a more electroactive compound than p-nitrophenol. The electrochemical oxidation current of hydroquinone formed in biodegradation of p-nitrophenol was measured at Moraxella sp.-modified carbon paste electrode and correlated to p-phenol concentrations. The optimum response was realized by electrode constructed using 15 mg of dry cell weight per 1 g of carbon paste and operating at 0.3 V (versus Ag/AgCl reference) in pH 7.5, 20 mM sodium phosphate buffer. Operating at these optimum conditions the biosensor had excellent selectivity against phenol derivatives and was able to measure as low as 20 nM (2.78 ppb) p-nitrophenol with very good accuracy and reproducibility. The biosensor was stable for approximately 3 weeks when stored at 4 degrees C. The applicability of the biosensor to measure p-nitrophenol in lake water was demonstrated.