2058 research outputs found
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Palladium(0)-Catalyzed Intramolecular Decarboxylative Allylation of Ortho Nitrobenzoic Esters
No full textA Pd/Ag bimetallic system has been developed for the
decarboxylative allylation of ortho-nitrobenzoic esters in an intramolecular fashion. In contrast to the typical sp2−sp3 cross-coupling approach which requires air and moisture sensitive preformed organometallic reagents, we
provide an alternative route to the synthesis of ortho-allyl nitroarenes from the corresponding ortho-nitrobenzoic acid derivatives. The reaction proceeds through a mechanistically distinct decarboxylative metalation pathway. A cooperative reactivity of palladium and silver is crucial for the reaction outcome
Cationic Liposomal Sodium Stibogluconate (SSG), a Potent Therapeutic Tool for Treatment of Infection by SSG-Sensitive and -Resistant Leishmania donovani
No full textPentavalent antimonials have been the first-line treatment for leishmaniasis for decades. However, the development of resistance to sodium stibogluconate (SSG) has limited its use, especially for treating visceral leishmaniasis (VL). The present work aims to optimize a cationic liposomal formulation of SSG for the treatment of both SSG-sensitive (AG83) and SSG-resistant (GE1F8R and CK1R) Leishmania donovani infections. Parasite killing was determined by the 3-(4,5-dimethylthiazol-2)-2,5-diphenyltetrazolium
bromide (MTT) assay and microscopic counting of Giemsa-stained macrophages. Macrophage uptake studies were carried out by confocal microscopic imaging. Parasite-liposome interactions were visualized through transmission electron
microscopy. Toxicity tests were performed using assay kits. Organ parasite burdens were determined by microscopic counting and limiting dilution assays. Cytokines were measured by enzyme-linked immunosorbent assays (ELISAs) and flow cytometry. Although all cationic liposomes studied demonstrated leishmanicidal activity, phosphatidylcholine (PC)-dimethyldioctadecylammonium bromide (DDAB) vesicles were most effective, followed by PC-stearylamine (SA) liposomes. Since entrapment of SSG in PC-DDAB liposomes demonstrated enhanced ultrastructural alterations in promastigotes, PC-DDAB-SSG vesicles were further investigated in vitro and in vivo. PC-DDAB-SSG could effectively alleviate SSG-sensitive and SSG-resistant L. donovani infections in the liver, spleen, and bone marrow of BALB/c mice at a dose of SSG (3 mg/kg body weight) not reported previously. The parasiticidal activity of these vesicles was attributed to better interactions with the parasite membranes, resulting in direct killing, and generation of a strong host-protective environment, necessitating a very low dose of SSG for effective cures
Novel lysosome targeted molecular transporter built on a guanidinium-poly-(propylene imine) hybrid dendron for efficient delivery of doxorubicin into cancer cells
No full textAn efficient synthetic approach has been adopted to construct a new dendron-based octa-guanidine appended molecular transporter with a lysosomal targeted peptide–doxorubicin conjugate. The transporter alone (G8-PPI-FL) is found to be non-toxic, showed higher cellular
uptake compared to Arg-8-mer and exhibited excellent selectivity towards lysosomes in cathepsin B expressing HeLa cells, while the Dox-conjugate showed significant cytotoxicity to cancer cells without affecting the non-cancerous cells
Molecular modelling approaches for designing inhibitors of L-amino acid oxidase from Crotalus adamanteus venom
No full textL-amino acid oxidase (LAAO) from snake venom
induces diverse toxicity into the victims, which is attributed to H2O2 generated during the catalytic conversion
of L-amino acids. In this study, homology model of LAAO from Crotalus adamanteus has been compared with the crystal structure of LAAO from Calloselasma rhodostoma. The root mean square deviations obtained from superposition of the FADbinding, substrate-binding and helical domains of
LAAO from Crotalus adamanteus with those of LAAO from Calloselasma rhodostoma crystal structure confirmed
a high degree of structural similarity between them. Based on the interactions of the substrate, L-phenylalanine and the reversible inhibitor, o-aminobenzoic acid with the catalytic residues of LAAO from Calloselasma rhodostoma, five probable inhibitors were designed. AutoDock Vina program was employed to perform automated molecular docking of these probable inhibitors. Two of them emerged as reversible inhibitors with IC50 values of 1.6 and 3.3 M
respectively
Cationic antimicrobial peptides in psoriatic skin cooperate to break innate tolerance to self-DNA
No full textPsoriasis is a T-cell-mediated skin autoimmune disease characterized by the aberrant activation of dermal dendritic cells (DCs) and the sustained epidermal expression of antimicrobial peptides. We have previously identified a link between these two events by showing that the cathelicidin antimicrobial peptide LL37 has the ability to trigger selfnucleic acid mediated activation of plasmacytoid DCs (pDCs) in psoriatic skin. Whether other cationic antimicrobial peptides exert similar activities is unknown. By analysing heparin-binding HPLC fractions of psoriatic scales, we found that human beta-defensin
(hBD)2, hBD3, and lysozyme are additional triggers of pDC activation in psoriatic skin lesions. Like LL37, hBD2, hBD3, and lysozyme are able to condense self-DNA into particles that are endocytosed by pDCs, leading to activation of TLR9. In contrast, other antimicrobial peptides expressed in psoriatic skin including elafin, hBD1, and psoriasin (S100A7) did not show similar activities. hBD2, hBD3, and lysozyme were detected in
psoriatic skin lesions in the vicinity of pDCs and found to cooperate with LL37 to induce high levels of IFN production by pDCs, suggesting their concerted role in the pathogenesis
of psoriasis
An Inducible and Secreted Eukaryote-Like Serine/Threonine Kinase of Salmonella enterica Serovar Typhi Promotes Intracellular Survival and Pathogenesis
No full textEukaryote-like serine/threonine kinases (eSTKs) constitute an important family of bacterial virulence factors. Genome analysis had predicted putative eSTKs in Salmonella enterica serovar Typhi, although their functional characterization and the elucidation of their role in pathogenesis are still awaited. We show here that the primary sequence and secondary structure of the t4519
locus of Salmonella Typhi Ty2 have all the signatures of eukaryotic superfamily kinases. t4519 encodes a�39-kDa protein (T4519), which shows serine/threonine kinase activities in vitro. Recombinant T4519 (rT4519) is autophosphorylated and phosphorylates the universal substrate myelin basic protein. Infection of macrophages results in decreased viability of the mutant (Ty2�t4519) strain, which is reversed by gene complementation. Moreover, reactive oxygen species produced by the macrophages signal to the bacteria to induce T4519, which is translocated to the host cell cytoplasm. That T4519 may target a host substrate(s) is further supported by the activation of host cellular signaling pathways and the induction of cytokines/chemokines.Finally, the role of T4519 in the pathogenesis of Salmonella Typhi is underscored by the significantly decreased mortality of mice
infected with the Ty2�t4519 strain and the fact that the competitive index of this strain for causing systemic infection is 0.25% that of the wild-type strain. This study characterizes the first eSTK of Salmonella Typhi and demonstrates its role in promoting phagosomal survival of the bacteria within macrophages, which is a key determinant of pathogenesis. This, to the best of our knowledge, is the first study to describe the essential role of eSTKs in the in vivo pathogenesis of Salmonella spp
Hesperetin Induces Apoptosis in Breast Carcinoma by Triggering Accumulation of ROS and Activation of ASK1/JNK Pathway
No full textHesperetin, a flavanone glycoside predominantly found in citrus fruits, exhibits a wide array of biological properties. In the present study hesperetin exhibited a significant cytotoxic effect in human breast carcinoma MCF-7 cells in a concentration- and time-dependent
manner without affecting normal (HMEC) as well as immortalized normal mammary epithelial cells (MCF-10A). The cytotoxic effect of hesperetin was due to the induction of apoptosis as evident from the phosphatidyl-serine externalization, DNA fragmentation, caspase-7 activation, and PARP cleavage. Apoptosis was associated with caspase-9 activation, mitochondrial membrane potential loss, release of cytochrome c, and increase in Bax:Bcl-2 ratio. Pre-treatment with caspase-9 specific inhibitor (Z-LEHD-fmk) markedly attenuated apoptosis suggesting an involvement of intrinsic mitochondrial apoptotic cascade. Further, DCFDA flow-cytometric analysis revealed triggering of ROS in a time-dependent manner. Pre-treatment with ROS scavenger N-acetylcysteine (NAC) and glutathione markedly abrogated hesperetin-mediated apoptosis whereas carbonyl cyanide m-chlorophenylhydrazone (CCCP) pretreatment along with
DHR123-based flow-cytometry indicated the generation of cytosolic ROS. Profiling of MAPKs revealed activation of JNK upon hesperetin treatment which was abrogated upon NAC pre-treatment. Additionally, inhibition of JNK by SP600125 significantly reversed hesperetinmediated apoptosis. The activation of JNK was associated with the activation of ASK1. Silencing of ASK1 resulted in significant attenuation
of JNK activation as well as reversed the hesperetin-mediated apoptosis suggesting that hesperetin-mediated apoptosis of MCF-7 cells involves accumulation of ROS and activation of ASK1/JNK pathway. In addition, hesperetin also induced apoptosis in triple negative breast
cancer MDA-MB-231 cells via intrinsic pathway via activation of caspase -9 and -3 and increase in Bax:Bcl-2 ratio
Deregulation of Rb-E2F1 Axis Causes Chromosomal Instability by Engaging the Transactivation Function of Cdc20–Anaphase-Promoting Complex/Cyclosome
No full textThe E2F family of transcription factors regulates genes involved in various aspects of the cell cycle. Beyond the well-documented role in G1/S transition, mitotic regulation by E2F has also been reported. Proper mitotic progression is monitored by the spindle assembly checkpoint (SAC). The SAC ensures bipolar separation of chromosomes and thus prevents aneuploidy. There are limited reports on the regulation of the SAC by E2F. Our previous work identified the SAC protein Cdc20 as a novel transcriptional regulator of the mitotic ubiquitin carrier protein UbcH10. However, none of the Cdc20 transcription complex proteins have any
known DNA binding domain. Here we show that an E2F1-DP1 heterodimer is involved in recruitment of the Cdc20 transcription complex to the UBCH10 promoter and in transactivation of the gene. We further show that inactivation of Rb can facilitate this transactivation process. Moreover, this E2F1-mediated regulation of UbcH10 influences mitotic progression. Deregulation of this pathway results in premature anaphase, chromosomal abnormalities, and aneuploidy. We conclude that excess E2F1 due to Rb inactivation recruits the complex of Cdc20 and the anaphase-promoting complex/cyclosome (Cdc20-APC/C) to deregulate the expression of UBCH10, leading to chromosomal instability in cancer cells
TALEN mediated targeted editing of GM2/GD2-synthase gene modulates anchorage independent growth by reducing anoikis resistance in mouse tumor cells
No full textComplex ganglioside expression is highly deregulated in several tumors which is further dependent on
specific ganglioside synthase genes. Here, we designed and constructed a pair of highly specific
transcription-activator like effector endonuclease (TALENs) to disrupt a particular genomic locus of mouse
GM2-synthase, a region conserved in coding sequence of all four transcript variants of mouse
GM2-synthase. Our designed TALENs effectively work in different mouse cell lines and TALEN induced
mutation rate is over 45%. Clonal selection strategy is undertaken to generate stable GM2-synthase
knockout cell line. We have also demonstrated non-homologous end joining (NHEJ) mediated integration
of neomycin cassette into the TALEN targeted GM2-synthase locus. Functionally, clonally selected
GM2-synthase knockout clones show reduced anchorage-independent growth (AIG), reduction in tumor
growth and higher cellular adhesion as compared to wild type Renca-v cells. Insight into the mechanism
shows that, reduced AIG is due to loss in anoikis resistance, as both knockout clones show increased
sensitivity to detachment induced apoptosis. Therefore, TALEN mediated precise genome editing at
GM2-synthase locus not only helps us in understanding the function of GM2-synthase gene and complex
gangliosides in tumorigenicity but also holds tremendous potential to use TALENs in translational cancer
research and therapeutics
New flavonoid glycosides and other chemical constituents from Clerodendrum phlomidis leaves: isolation and characterisation
No full textPhytochemical investigation of the plant Clerodendrum phlomidis Linn. F.(Lamiaceae) has now led to the isolation of two new flavonoid glycosides (1, 2) together with six known compounds identified as pectolinaringenin (3), pectolinaringenin- 7-O-b-D-glucopyranoside (4), 24b-ethylcholesta-5,22E,25-triene-3b-ol (5),24b-ethylcholesta-5,22E,25-triene-3b-O-b-D-glucopyranoside (6), (2S,3S,4R,10E)-2- [(20R)-20-hydroxytetracosanoylamino]-10-octadecene-1,3,4-triol (7) and andrographolide
(8) mainly by spectroscopic analysis. Compounds 4 and 6–8 are reported for the first time from C. phlomidis