Selective reactivity of 2-mercaptoethanol with 5beta,6beta-epoxide in steroids from Withania somnifera

2-Mercaptoethanol reacts selectively with the 5beta,6beta-epoxy steroids isolated from Withania somnifera substituting the epoxide by a six-membered oxyethylene-2'-thio ring whereas it failed to show such reactivity on 6alpha,7alpha-epoxy withasteroids. The structure of the product has been elucidated by spectroscopic methods, especially applying extensive 2D NMR methods. The anticancer activity of withaferin A was lost in the reaction product indicating that its activity is also linked to the free 5beta,6beta-epoxide functional group.     

Effect of melatonin on the cardiotoxicity of doxorubicin

This study was designed to investigate the preventive effect of melatonin on doxorubicin's most important side effect, cardiotoxicity. Forty male albino Wistar rats were utilized and the rats were divided into five groups: group I, 0.9% NaCl for 4 days; group II, doxorubicin 3 mg/kg/day for 4 days; group III, 2.5 % ethanol for 15 days; group IV, melatonin 6 mg/kg/day for 15 days; and group V, a doxorubicin and melatonin combination were administered intraperitoneally. At the end of the experiment, tissue samples obtained from the cardiac muscle of the left ventricle of the rats were processed for measurement of malondialdehyde and for electron microscopic examination. Malondialdehyde, a product of lipid peroxidation, was found to be significantly higher in the doxorubicin group. However, in the doxorubicin and melatonin combination group the level of malondialdehyde was decreased statistical significant. The histological examination revealed destruction of myofibrils, disorganization of sarcomeres, mitochondrial degeneration and formation of giant mitochondria and lipid accumulation in the doxorubicin group. Also, accumulation of filamentous structures in the sarcoplasma in some of the cells, structural changes in capillaries and an increase in collagen fibers forming bundles were observed. When melatonin was added to the doxorubicin treatment all structural changes were reduced. The cardiotoxic side effect of doxorubicin used as a chemotherapeutic agent and was probably developed as a result of suppression of the antioxidant system and lipid peroxidation. Therefore, it could be assumed that the addition of melatonin in the treatment of doxorubicin could prevent the cardiotoxicity of doxorubicin.     

Transforming growth factor-beta-mediated chondrogenesis of human mesenchymal progenitor cells involves N-cadherin and mitogen-activated protein kinase and Wnt signaling cross-talk

The multilineage differentiation potential of adult tissue-derived mesenchymal progenitor cells (MPCs), such as those from bone marrow and trabecular bone, makes them a useful model to investigate mechanisms regulating tissue development and regeneration, such as cartilage. Treatment with transforming growth factor-beta (TGF-beta) superfamily members is a key requirement for the in vitro chondrogenic differentiation of MPCs. Intracellular signaling cascades, particularly those involving the mitogen-activated protein (MAP) kinases, p38, ERK-1, and JNK, have been shown to be activated by TGF-betas in promoting cartilage-specific gene expression. MPC chondrogenesis in vitro also requires high cell seeding density, reminiscent of the cellular condensation requirements for embryonic mesenchymal chondrogenesis, suggesting common chondro-regulatory mechanisms. Prompted by recent findings of the crucial role of the cell adhesion protein, N-cadherin, and Wnt signaling in condensation and chondrogenesis, we have examined here their involvement, as well as MAP kinase signaling, in TGF-beta1-induced chondrogenesis of trabecular bone-derived MPCs. Our results showed that TGF-beta1 treatment initiates and maintains chondrogenesis of MPCs through the differential chondro-stimulatory activities of p38, ERK-1, and to a lesser extent, JNK. This regulation of MPC chondrogenic differentiation by the MAP kinases involves the modulation of N-cadherin expression levels, thereby likely controlling condensation-like cell-cell interaction and progression to chondrogenic differentiation, by the sequential up-regulation and progressive down-regulation of N-cadherin. TGF-beta1-mediated MAP kinase activation also controls WNT-7A gene expression and Wnt-mediated signaling through the intracellular beta-catenin-TCF pathway, which likely regulates N-cadherin expression and subsequent N-cadherin-mediated cell-adhesion complexes during the early steps of MPC chondrogenesis.     

The European Bioinformatics Institute's data resources

As the amount of biological data grows, so does the need for biologists to store and access this information in central repositories in a free and unambiguous manner. The European Bioinformatics Institute (EBI) hosts six core databases, which store information on DNA sequences (EMBL-Bank), protein sequences (SWISS-PROT and TrEMBL), protein structure (MSD), whole genomes (Ensembl) and gene expression (ArrayExpress). But just as a cell would be useless if it couldn't transcribe DNA or translate RNA, our resources would be compromised if each existed in isolation. We have therefore developed a range of tools that not only facilitate the deposition and retrieval of biological information, but also allow users to carry out searches that reflect the interconnectedness of biological information. The EBI's databases and tools are all available on our website at www.ebi.ac.uk.     

Unusually sulfated and oxygenated steroids from Withania somnifera

Four (1, 8-10) and six known (2-7) withanolides were isolated from the leaves of Withania somnifera. Among the new compounds, 10 possessed the rare 3-O-sulfate group with the saturation in A ring and 9 contained unusual 1,4-dien-3-one group. Compound 8 did not have usual 2,3 unsaturation in A ring while 1 had the rare C-16 double bond. The structures of all the compounds were elucidated by spectroscopic methods and chemical transformation.     

Cloning and expression inEscherichia coli of entomotoxic protein gene fromBacillus thuringiensis subspecieskurstaki

A plasmid borne larvicidal crystal protein gene from B.thuringiensis subspecieskurstaki was cloned inEscherichia coli using a specific 20-mer oligonucleotide probe. The gene expressed inE. coli at a high level. TransgenicE. coli cells produced large irregular bodies which looked bright under phase contrast microscopy. The phase bright bodies released by sonic disruption of cells could be pelleted by centrifugation. Toxicity trials on the larvae ofSpodoptera litura showed that the pellet was antifeedant and toxic to the larvae. The supernatant was only mildly antifeedant. Even short term feeding of larvae on the toxin delayed the onset of pupation.     

Enzymatic dehydration of 3-hydroxymethyloxindole

Crude and partially purified extracts of wheat (Triticum vulgare, red variety) germ catalyze the dehydration of 3-hydroxymethyloxindole to 3-methyleneoxindole. Examination of the ultraviolet absorption spectrum of a reaction mixture consisting of either the extract or partially purified enzyme and 3-hydroxymethyloxindole, shows that this oxindole has undergone complete dehydration to 3-methyleneoxindole. TPNH-linked 3-methyleneoxindole reductase, also a constituent of the wheat germ extract, can be separated from the dehydrase by passage through an Agarose 15 column. Utilizing these partially purified enzymes, it can be demonstrated that the dehydrase activity found in wheat germ is a discrete enzymatic function.