Self-organizing molecular field analysis on pregnane derivatives as human steroidal 5α-reductase inhibitors

Normal growth and development of human prostate is regulated by the androgens which balances cell proliferation and apoptosis. Testosterone (T) and dihydrotestosterone (DHT) are the two key androgens that stimulate most of the androgen action in prostate. Testosterone is converted to DHT by the membrane bound NADPH-dependent 5α-reductase enzyme. As a consequence of the important observation that progesterone and deoxycortisone inhibits the synthesis of DHT by competing with 4-en-3-one function of the testosterone for the 5α-reductase enzyme a number of pregnane derivatives were synthesized and have been reported as inhibitors of human 5α-reductase enzyme. Due to lack of information on the crystal structure of human 5α-reductase, ligand-based 3D-QSAR study has been performed on pregnane derivatives using self-organizing molecular field analysis (SOMFA) for rationalizing the molecular properties and human 5α-reductase inhibitory activities. The statistical results having good cross-validated (0.881), non-cross-validated r² (0.893) and F-test value (175.527), showed satisfied predictive ability (0.777). Analysis of SOMFA models through electrostatic and shape grids provide useful information for the design and optimization of steroidal structure as novel human 5α-reductase inhibitors.     

Chimeric peptide of Met-enkephalin and FMRFa induces antinociception and attenuates development of tolerance to morphine antinociception.

A synthetic chimeric peptide of Met-enkephalin and FMRFamide (YGGFMKKKFMRFa), based on MERF was synthesized. This peptide was tested for possible antinociceptive effects using the tail flick test in mice. The effect of the chimeric peptide on morphine antinociception and development of tolerance to the antinociceptive action of morphine was also investigated. The chimeric peptide produced significant, dose-dependent antinociception (40, 60 and 90 mg/kg) in the tail flick test. Pretreatment with naloxone (5 mg/kg, IP) significantly attenuated the antinociceptive effect induced by the chimeric peptide (90 mg/kg, IP), indicating involvement of an opioidergic mechanism. In combination experiments with morphine, the antinociceptive dose of the chimeric peptide (60 mg/kg, IP) potentiated morphine (7 mg/kg, IP) antinociception. A low dose of the chimeric peptide (10 mg/kg, IP), that did not produce significant antinociception on its own, also potentiated morphine antinociception. In the tolerance studies, male albino mice received twice daily injections of morphine (20 mg/kg, IP) followed by either saline (0.1 ml) or chimeric peptide (80 mg/kg, IP) for a period of 4 days. A control group received twice daily injections of saline (0.1 ml) for the same period. When tested on Day 5, tolerance to antinociceptive action of morphine (15 mg/kg, IP) was evidenced by decreased response in chronic morphine plus saline treated mice compared to control group. Concurrent administration of chimeric peptide (80 mg/kg, IP) with morphine significantly attenuated the development of tolerance to the antinociceptive action of morphine. The preliminary results of this study demonstrate that peripherally administered chimeric peptide can produce dose dependent, naloxone reversible, antinociception; potentiate morphine antinociception and attenuate morphine tolerance, indicating a possible role of these type of amphiactive sequences in antinociception and its modulation. These chimeric peptides may also prove to be useful tools for further ascertaining the role of FMRFa family of peptides in mechanisms leading to opiate tolerance and dependence.     

Effect of diabetes on calcium/calmodulin dependent protein kinase-II from rat brain.

Changes in the protein levels and activity of Ca2+/Calmodulin dependent protein kinase II (CaM kinase II) level were studied in cytosolic and particulate fractions from cerebral hemisphere, cerebellum, brain stem, thalamus and hypothalamus regions of rat brain after 4 and 12 weeks of induction of diabetes. Streptozotocin induced diabetes, resulted in pronounced increase of CaM kinase II activity as determined by the kinase activity assay. The total amount of enzyme protein (alpha-subunit specific) also showed increase as revealed by western blotting. Parallel studies were also made in age matched control rats and insulin treated diabetic rats. The increase in CaM kinase II activity was more pronounced in the 12 weeks diabetic group. Insulin treatment of diabetic rats, resulted in recovery of enzyme activity near to control values from majority of the brain regions studied. The expression of alpha-subunit specific CaM kinase II correlates with the enzyme activity in the diabetic rat brain.     

Correlation between gene expression profiles and protein-protein interactions within and across genomes

MOTIVATION: Function annotation of an unclassified protein on the basis of its interaction partners is well documented in the literature. Reliable predictions of interactions from other data sources such as gene expression measurements would provide a useful route to function annotation. We investigate the global relationship of protein-protein interactions with gene expression. This relationship is studied in four evolutionarily diverse species, for which substantial information regarding their interactions and expression is available: human, mouse, yeast and Escherichia coli. RESULTS: In E.coli the expression of interacting pairs is highly correlated in comparison to random pairs, while in the other three species, the correlation of expression of interacting pairs is only slightly stronger than that of random pairs. To strengthen the correlation, we developed a protocol to integrate ortholog information into the interaction and expression datasets. In all four genomes, the likelihood of predicting protein interactions from highly correlated expression data is increased using our protocol. In yeast, for example, the likelihood of predicting a true interaction, when the correlation is > 0.9, increases from 1.4 to 9.4. The improvement demonstrates that protein interactions are reflected in gene expression and the correlation between the two is strengthened by evolution information. The results establish that co-expression of interacting protein pairs is more conserved than that of random ones.     

Peptidic nanoparticles: for cancer diagnosis and therapy

A challenging topic in cancer research is to create drug delivery system that can bring in a specific and noncytotoxic manner a therapeutic compound. Usually, tumor targeting requires very specific compounds. Currently, peptide analogues like somatostatin, neurotensin, or bombesin are used to target G-coupled receptors, which are overexpressed on tumor cells. However, many of those analogues are rapidly degraded in the plasma and are cytotoxic [1–2]. Due to the limited efficiency and high toxicity of conventional chemotherapy different strategies have been developed for non-cytotoxic cancer treatment and cancer localization [3–5]. The recent development in bio-nanotechnology offers new avenues for cancer therapy. A lot of studies have been devoted to nanoparticulate delivery systems (10–100nm) like lipid or polymer particles [6–8]. Due to the nanometer sized of such cargos, the transportation of therapeutic compounds in the blood stream is increased in terms of time circulation. But their surface functionalization to improve drug-targeting properties is usually complicated and rather uneffective. We have recently designed a novel type of functional nanoparticles with regular icosahedral symmetry, mimicking small, rigid viral capsids (Fig. 1 (A)) and a diameter of about 17 nm (Fig. 1 (C)) which self-assemble from single polypeptide chains (Fig. 1 (B)).     

Improvement of alignment accuracy utilizing sequentially conserved motifs

Background  

Multiple sequence alignment algorithms are very important tools in molecular biology today. Accurate alignment of proteins is central to several areas such as homology modelling, docking studies, understanding evolutionary trends and study of structure-function relationships. In recent times, improvement of existing progressing programs and implementation of new iterative algorithms have made a significant change in this field.     

P-450 epoxygenase and NO synthase inhibitors reduce cerebral blood flow response to N-methyl-D-aspartate

Epoxyeicosatrienoic acids are cerebral vasodilators produced in astrocytes by cytochrome P-450 epoxygenase activity. The P-450 inhibitor miconazole attenuates the increase in cerebral blood flow (CBF) elicited by glutamate. We evaluated whether epoxygenase activity is involved in the CBF response to activation of the N-methyl-D-aspartate (NMDA) receptor subtype by using two structurally distinct inhibitors, miconazole and N-methylsulfonyl-6-(2-propargyloxyphenyl) hexanamide (MS-PPOH), a selective epoxygenase substrate inhibitor. Drugs were delivered locally through microdialysis probes in striata of anesthetized rats. Local CBF was measured by hydrogen clearance and compared with CBF in contralateral striatum receiving vehicle. Microdialysis perfusion of NMDA doubled CBF and increased nitric oxide (NO) production estimated by recovery of labeled citrulline in the dialysate during labeled arginine infusion. Perfusion of miconazole or MS-PPOH blocked the increase in CBF without decreasing citrulline recovery. Perfusion of N(omega)-nitro-L-arginine decreased baseline CBF and inhibited the CBF response to NMDA. Perfusion of MS-PPOH did not inhibit the CBF response to sodium nitroprusside. We conclude that both the P-450 epoxygenase and NO synthase pathways are involved in the local CBF response to NMDA receptor activation, and that the signaling pathway may be more complex than simply NO diffusion from neurons to vascular smooth muscle.     

In vitro propagation,clonal fidelity and phytochemical analysis of <Emphasis Type="Italic">Rhodiola imbricata</Emphasis> Edgew: a rare trans-Himalayan medicinal plant

The present study focuses on development of a micropropagation protocol for true to type plants of Rhodiola imbricata, an endangered medicinal plant found in trans-Himalayan Leh-Ladakh region of India. It also aims at analyzing the pharmaceutically important secondary metabolites and antioxidant potential of in vitro and in vivo plants. Various cytokinins and auxins were tested for shoot proliferation and in vitro rooting of the microshoots, respectively. Random primers were used for checking genetic uniformity at different stages of micropropagation. Pharmaceutically important secondary metabolites of R. imbricata such as Rosavin, total polyphenols and free radical scavenging activity were analyzed by HPLC. Among different cytokinins used, BAP (5 µM) and TDZ (1 µM) were found to perform better in terms of shoot proliferation, shoot length and number of leaves as compared to other concentrations. For rooting of microshoots, a lower concentration of NAA (0.5 µM) yielded more efficient rooting of micro shoots (17.33 roots per micro shoot). In vitro rooted microshoots were hardened and showed 60% survival rate. The content of gallic acid, chlorogenic acid and 4-hydroxybenzoic acid was higher in the in vivo plant. The amount of ferulic acid was higher in the in vitro raised plant when compared to field grown plant. Furthermore, caffeic acid and p-coumaric acid were higher in the in vitro raised plants as compared to field grown plants. This work will facilitate in conservation of this endangered herb and provide necessary plant materials for various biotechnological and pharmaceutical applications.