A novel synthesis of 2-arylbenzimidazoles in molecular sieves-MeOH system and their antitubercular activity

Arylbenzimidazoles have been synthesized as antimycobacterial agents. An efficient synthesis has been developed for 2-arylbenzimidazoles from o-phenylenediamines and aromatic aldehydes in molecular sieves-methanol system. The methodology is straightforward to get 2-arylbenzimidazoles (3a–3z) in excellent yields with high chemoselectivity over 2-aryl-1-benzylbenzimidazoles (4a–4z). All these benzimidazole analogues were evaluated against M. tuberculosis in BACTEC radiometric assay. The compounds 4y and 4z exhibited potential antitubercular activity against M. tuberculosis H₃₇R_V, MIC at 16?µM and 24?µM respectively. The best compound of the series i.e. compound 4y was well tolerated by Swiss-albino mice in acute oral toxicity. Compound 4y possessing a diarylbenzimidazole core, can further be optimized for better activity.     

Extraction,profiling and bioactivity analysis of volatile glucosinolates present in oil extract of <Emphasis Type="Italic">Brassica juncea</Emphasis> var. <Emphasis Type="Italic">raya</Emphasis>

Cruciferous vegetables are rich source of glucosinolates (GSLs), which in presence of myrosinase enzyme cause hydrolytic cleavage and result in different hydrolytic products like isothiocyanates, thiocyanates, nitriles and epinitriles. The GSLs hydrolytic products are volatile compounds, which are known to exhibit bioactivities like antioxidant, fungicidal, bioherbicidal and anticancer. Among the Brassicaceae family, Brassica juncea is very well known for high content of GSLs. In the present study, the isolation of volatile oil of B. juncea var. raya was done by hydrodistillation method using clevenger apparatus and further there extraction was done by solvents ethyl acetate and dichloromethane. The volatile compounds present in the extract were analysed by gas chromatography/gas chromatography–mass spectrometry (GC/GC–MS). Fatty acid esters, sulphur and/or nitrogen compounds, carbonyl compounds and some other volatile compounds were also identified. Besides the analytical studies, the extracts were analysed for their bioactivities including radical scavenging activity by using DNA nicking assay and cytotoxic effect using different human cancer cell lines viz. breast (MCF-7 and MDA-MB-231), prostate (PC-3), lung (A-549), cervix (HeLa) and colon (HCT116) by MTT assay. The oil extracts were efficiently able to reduce the increase of cancer cells in a dose-dependent manner. Among all cell lines, the most effective anticancer activity was observed in case of breast (MCF-7) cancer cell line. So, MCF-7 cells were used for further mechanistic studies for analysing the mechanism of anticancer activity. Confocal microscopy was done for analysing morphological changes in the cells and the images confirmed the features typical of apoptosis. For evaluating the mode of cell death, spectrofluorometric determination of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) was done. The volatile oil extract treated MCF-7 cells had a significant increase in number of ROS, also there was a rise in percentage of cells with increased disruption of MMP. So, the present study marks necessary indication that B. juncea (raya) oil extracts significantly induces apoptosis in all the above mentioned cancer cells lines through a ROS-mediated mitochondrial pathway and thus play a remarkable role in death of cancer cells.     

Successful percutaneous retrieval of unusually knotted temporary pacemaker lead

Implantation of temporary pacemaker lead is commonly performed procedure and is usually safe, but can sometimes develop rare and serious complication like intracardiac lead knotting which may require challenging retrieval techniques. We report a case of successful percutaneous retrieval of unusually knotted right internal jugular venous temporary pacing lead via left femoral transvenous approach using snare over a long sheath after cutting the electrode proximally and thus avoiding any surgical intervention.     

Immunomodulation of dual specificity phosphatase 4 during visceral leishmaniasis

DUSP4, an inducible protein has a substrate specificity toward ERK1/2, a component of MAP kinase which is enhanced during Leishmania infection. The DUSP4^?/? mice show increased susceptibility towards the infection caused by Toxoplasma gondii and Leishmania mexicana. These observations emphatically established the fact that unlike DUSP1, DUSP4 has host protective role. In our study, it has been Leishmania donovani, the causative agent of visceral leishmaniasis (VL) significantly reduced the expression of DUSP4 during infection. In order to find out the host protective role of DUSP4 in macrophages during VL, we silenced DUSP4 prior to infection and the parasite number within macrophage was counted. Under DUSP4 knock-down condition, phosphorylation of p38 MAPK and generation of pro-inflammatory response like IL-12, TNF-α, and iNOS was decreased significantly. Silencing DUSP4 promoted the phosphorylation of ERK1/2 and the generation of anti-inflammatory response like- IL-10, TGF-β with increased Arginase-1 and Cox-2 activity. Glycyrrhizic Acid (GA), an immunomodulator, already known to suppress L. donovani infection, found to up-regulate DUSP4 expression during L. donovani infection. On the other hand, GA failed to increase Th1 cytokine production and decrease Th2 response during DUSP4 knock-down condition suggesting the key role of DUSP4 while providing protection during L. donovani infection.     

Photobacterium marinum sp. nov., a marine bacterium isolated from a sediment sample from Palk Bay,India

The novel, cream colored, Gram-staining-negative, rod-shaped, motile bacteria, designated strains AK15^T and AK18, were isolated from sediment samples collected from Palk Bay, India. Both strains were positive for arginine dihydrolase, lysine decarboxylase, oxidase, nitrate reduction and methyl red test. The major fatty acids were C_16:0, C_{18:1 ω7c}, C_{16:1 ω7c} and/or C_{16:1 ω6c} and/or iso-C_15:0 2-OH (summed feature 3). Polar lipids content of strains AK15^T and AK18 were found to bephosphatidylethanolamine (PE), two unidentified phospholipids (PL1 and PL2) and three unidentified lipids (L1-L3). The 16S rRNA gene sequence analysis indicated strains AK15^T and AK18 as the members of the genus Photobacterium and closely related to the type strain Photobacterium jeanii with pair-wise sequence similarity of 96.7%. DNA–DNA hybridization between strain AK15^T and AK18 showed a relatedness of 87%. Based on data from the current polyphasic study, strains AK15^T and AK18 are proposed as novel species of the genus Photobacterium, for which the name Photobacterium marinum sp. nov. is proposed. The type strain of Photobacterium marinum is AK15^T (=MTCC 11066^T = DSM 25368^T).     

Protein Structure Evaluation using an All-Atom Energy Based Empirical Scoring Function

Abstract

Arriving at the native conformation of a polypeptide chain characterized by minimum most free energy is a problem of long standing interest in protein structure prediction endeavors. Owing to the computational requirements in developing free energy estimates, scoring functions—energy based or statistical—have received considerable renewed attention in recent years for distinguishing native structures of proteins from non-native like structures. Several cleverly designed decoy sets, CASP (Critical Assessment of Techniques for Protein Structure Prediction) structures and homology based internet accessible three dimensional model builders are now available for validating the scoring functions. We describe here an all-atom energy based empirical scoring function and examine its performance on a wide series of publicly available decoys. Barring two protein sequences where native structure is ranked second and seventh, native is identified as the lowest energy structure in 67 protein sequences from among 61,659 decoys belonging to 12 different decoy sets. We further illustrate a potential application of the scoring function in bracketing native-like structures of two small mixed alpha/beta globular proteins starting from sequence and secondary structural information. The scoring function has been web enabled at www.scfbio-iitd.res.in/utility/proteomics/energy.jsp     

Counterbalance of ligand‐ and self‐coupled motions characterizes multispecificity of ubiquitin

Date hub proteins are a type of proteins that show multispecificity in a time‐dependent manner. To understand dynamic aspects of such multispecificity we studied Ubiquitin as a typical example of a date hub protein. Here we analyzed 9 biologically relevant Ubiquitin‐protein (ligand) heterodimer structures by using normal mode analysis based on an elastic network model. Our result showed that the self‐coupled motion of Ubiquitin in the complex, rather than its ligand‐coupled motion, is similar to the motion of Ubiquitin in the unbound condition. The ligand‐coupled motions are correlated to the conformational change between the unbound and bound conditions of Ubiquitin. Moreover, ligand‐coupled motions favor the formation of the bound states, due to its in‐phase movements of the contacting atoms at the interface. The self‐coupled motions at the interface indicated loss of conformational entropy due to binding. Therefore, such motions disfavor the formation of the bound state. We observed that the ligand‐coupled motions are embedded in the motions of unbound Ubiquitin. In conclusion, multispecificity of Ubiquitin can be characterized by an intricate balance of the ligand‐ and self‐coupled motions, both of which are embedded in the motions of the unbound form.     

Cytoskeletal elements and intracellular transport

Recent advances in the understanding of the functions of various components of the cytoskeleton indicate that, besides serving a structural role, the cytoskeletal elements may regulate the transport of several proteins in the cell. Studies reveal that there are co-operative interactions between the actin and microtubule cytoskeletons including functional overlap in the transport influenced by different motor families. Multiple motors are probably involved in the control of the dynamics of many proteins and intriguing hints about how these motors are co-ordinated are appearing. It has been shown that some of the intermediate elements also participate in selected intracellular transport mechanisms. In view of the author's preoccupation with the steroid receptor systems, special attention has been given to the role of the cytoskeletal elements, particularly actin, in the intracellular transport of steroid receptors and receptor-related proteins.