Design and synthesis of 2-substituted benzoxazoles as novel PTP1B inhibitors

A series of benzoxazole compounds containing oxamic acid were synthesized and screened for the PTP1B inhibition. Compound 31d showed best biochemical potency (K_i) of 6.7 μM. Structure–activity relationship were explained with the help of molecular modeling approach.     

Amino acids derived benzoxazepines: Design,synthesis and antitumor activity

Two series of new benzoxazepines substituted with different alkyl amino ethyl chains were synthesized comprising synthetic steps of inter and intramolecular Mitsunobu reaction, lithium aluminium hydride (LAH) reduction, debenzylation, bimolecular nucleophilic substitution (S_N2) reaction. The present study investigates the effect of a tyrosine-based benzoxazepine derivative in human breast cancer cells MCF-7 and MDA-MB-231 and in breast cancer animal model. The anti-proliferative effect of 15a on MCF-7 cells was associated with G1 cell-cycle arrest. This G1 growth arrest was followed by apoptosis as 15a dose dependently increased phosphatidylserine exposure, PARP cleavage and DNA fragmentation that are hallmarks of apoptotic cell death. Interestingly, 15a activated components of both intrinsic and extrinsic pathways of apoptosis characterized by activation of caspase-8 and -9, mitochondrial membrane depolarization and increase in Bax/Bcl2 ratio. However, use of selective caspase inhibitors revealed that the caspase-8-dependent pathway is the major contributor to 15a-induced apoptosis. Compound 15a also significantly reduced the growth of MCF-7 xenograft tumors in athymic nude mice. Together, 15a could serve as a base for the development of a new group of effective breast cancer therapeutics.     

Establishment of Agrobacterium tumefaciens-mediated genetic transformation in Dunaliella bardawil

Dunaliella bardawil, a unicellular microalga, grows in relatively high concentrations of salt and has so far been refractory to Agrobacterium-mediated transformation. An inverse relationship between salt concentration and hygromycin resistance was observed. Co-cultivation at 0.2?M NaCl allowed growth of both D. bardawil and A. tumefaciens. Lowering salt concentrations also enabled the use of lower concentrations of hygromycin, the selection agent. Cells resistant to 100?mg?l^?1 hygromycin were selected and growth of Agrobacterium was completely eliminated in these cells using cefotaxime/potassium clavulanate. The concentration of sodium chloride was gradually increased to 1.0?M with simultaneous reduction of hygromycin concentration for better growth of D. bardawil. Agrobacterium was unable to survive in the growth medium used for Dunaliella. Expression of β-glucuronidase (uidA), green fluorescent protein (GFP) and hygromycin phosphotransferase (hpt) in the hygromycin-resistant culture was detected using X-gluc as substrate and Western blotting using GFP antibodies and RT-PCR respectively. Cells growing in 1.0?M NaCl (in the absence of hygromycin) retained their ability to grow in hygromycin even after 18 months of cultivation. These cells expressed GFP and PCR for hpt gene was positive. The stability of the integrated transgene and resistance to hygromycin in three different transformation events were ascertained periodically. Southern blotting of DNA extracted from hygromycin resistant cells (HRC) that were 15–18 months old established the presence of the integrated transgene in the DNA of D. bardawil. Results of the present study substantiate A. tumefaciens-mediated transformation of the unicellular marine alga D. bardawil. Agrobacterium tumefaciens-mediated transgene integration along with the massive outdoor cultivation methods used for D. bardawil may allow the commercial synthesis of secondary metabolites and heterologous proteins.     

Enhancing the Yield of Active Recombinant Chitobiase by Physico-Chemical and In Vitro Refolding Studies

Chitobiase (CHB) is an important enzyme for the production of N-acetyl-d-glucosamine from the chitin biopolymer in the series of chitinolytic enzymes. Majority of over-expressed CHB (58 %) in E. coli expression system led to formation of inclusion bodies. The production and soluble yield of active CHB was enhanced by co-expression with GroEL/ES chaperonin, optimizing culture conditions and solubilization followed by refolding of remaining inactive chitobiase present in the form of inclusion bodies. The growth of recombinant E. coli produced 42 % CHB in soluble form and the rest (~58 %) as inclusion bodies. The percentage of active CHB was enhanced to 71 % by co-expression with GroEL/ES chaperonin system and optimizing culture conditions (37 °C, 200 rpm, IPTG—0.5 mM, l-arabinose—13.2 mM). Of the remaining inactive CHB present in inclusion bodies, 37 % could be recovered in active form using pulsatile dilution method involving denaturants (2 M urea, pH 12.5) and protein refolding studies (1.0 M l-arginine, 5 % glycerol). Using combinatorial approach, 80 % of the total CHB expressed, could be recovered from cells grown in one litre of LB medium is a step forward in replacing hazardous chemical technology by biotechnological process for the production of NAG from chitinous waste.     

Colonization of nasal cavities by Staphylococcus epidermidis mitigates SARS-CoV-2 nucleocapsid phosphoprotein-induced interleukin (IL)-6 in the lung

Infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can trigger excessive interleukin (IL)-6 signalling, leading to a myriad of biological effects including a cytokine storm that contributes to multiple organ failure in severe coronavirus disease 2019 (COVID-19). Using a mouse model, we demonstrated that nasal inoculation of nucleocapsid phosphoprotein (NPP) of SARS-CoV-2 increased IL-6 content in bronchoalveolar lavage fluid (BALF). Nasal administration of liquid coco-caprylate/caprate (LCC) onto Staphylococcus epidermidis (S. epidermidis)-colonized mice significantly attenuated NPP-induced IL-6. Furthermore, S. epidermidis-mediated LCC fermentation to generate electricity and butyric acid that promoted bacterial colonization and activated free fatty acid receptor 2 (Ffar2) respectively. Inhibition of Ffar2 impeded the effect of S. epidermidis plus LCC on the reduction of NPP-induced IL-6. Collectively, these results suggest that nasal S. epidermidis is part of the first line of defence in ameliorating a cytokine storm induced by airway infection of SARS-CoV-2.     

Calcineurin activation is only one calcium-dependent step in cytotoxic T lymphocyte granule exocytosis

We have tested the idea that calcineurin, a calcium-dependent phosphatase that is critical for activating cytokine gene expression in helper T cells, plays a role in lytic granule exocytosis in cytotoxic T lymphocytes (CTLs). We used TALL-104 human leukemic CTLs as a model. Our results confirm an earlier report (Dutz, J. P., Fruman, D. A., Burakoff, S. J., and Bierer, B. E. (1993) J. Immunol. 150, 2591-2598) that immunosuppressive drugs inhibit exocytosis in CTLs stimulated either via the T cell receptor (TCR) or via TCR-independent soluble agents. Of the two recently reported alternate targets of immunosuppressive drugs (Matsuda, S., Shibasaki, F., Takehana, K., Mori, H., Nishida, E., and Koyasu, S. (2000) EMBO Rep. 1, 428-434 and Matsuda, S., and Koyasu, S. (2000) Immunopharmacology 47, 119-125), JNK is not required for lytic granule exocytosis, but we were not able to exclude a role for P38. Exocytosis could be inhibited by expressing GFP fused to a C-terminal fragment of CAIN (cabin 1), but not by expressing VIVIT-GFP. Finally, expressing either full-length or truncated constitutively active mutant calcineurin A enhanced lytic granule exocytosis. However, the mutant calcineurin was unable to support exocytosis when cells were stimulated in the absence of Ca2+ influx. Taken together, our results support the idea that activation of calcineurin is required for lytic granule exocytosis but suggest that it is not the sole Ca2+-dependent step.     

Characterization of pNiXa,a serpin of Xenopus laevis oocytes and embryos,and its histidine-rich,Ni(II)-binding domain

A Ni(II)-binding serpin, pNiXA, is abundant in Xenopus oocytes and embryos. Kinetic assays show that purified pNiXa strongly inhibits bovine α-chymotrypsin (K₁ = 3 mM), weakly inhibits porcine elastase (K₁ = 0.5 μM), and does not inhibit bovine trypsin. The reversible, slow-binding inhibition of α-chymotrypsin by pNiXa is unaffected by Ni(II). Ovochymase in egg exudates is inhibited by pNiXa, but to a limited extent, even at high pNiXa concentrations. An octadecapeptide that models the His-rich domain (-HRHRHEQQGHHDSAKHGH-) of pNiXa forms six-coordinate, octahedral Ni(II)-complexes when the N-terminus is acetylated, and a square-planar Ni(II)-complex when the N-terminus is unblocked. Spectroscopy reveals two distinct types of octahedral Ni(II)-coordination to the N-acetylated octadecapeptide, involving, respectively, 3–4 and 5–6 imidazole nitrogens; the octadecapeptide undergoes partial, reversible precipitation in pH-and Ni(II)-dependent fashion, suggesting an insoluble, Ni(II)-coupled (Hx)_n-dimer. Such (Hx)_n-peptide interaction is confirmed by an enzyme-linked biotin-avidin assay with N-biotin-KHRHRHE-amide and N-acetyl-KHRHRHE-resin beads, which become coupled after adding Ni(II) or Zn(II). H₂O₂ oxidation of 2′-deoxyguanosine to mutagenic 8-hydroxy-2′deoxyguanosine is enhanced by the octahedral Ni(II)-octadecapeptide complex, although the effect is more intense with the square-planar Ni(II) octadecapeptide complex. Immunoperoxidase staining of whole mounts wish pNiXa antibody shows that pNiXa is distributed throughout gastrula-stage embryos and is localized during organogenesis in the brain, eye, spinal cord, myotomes, craniofacial tissues, and other sites of Ni(II) induced anomalies. Patterns of pNiXa staining are similar in controls and Ni(II)-exposed embryos. Binding of Ni(II) to pNiXa may cause embryotoxicity by enhancing oxidative reactions that produce tissue injury and genotoxicity. Although the natural target proteinases for pNiXa inhibition have not been established, pNiXa may be an important regulator of proteolysis during embryonic development. © 1996 Wiley-Liss, Inc.