Atomically dispersed Pt-N-4 sites as efficient and selective electrocatalysts for the chlorine evolution reaction

Chlorine evolution reaction (CER) is a critical anode reaction in chlor-alkali electrolysis. Although precious metal-based mixed metal oxides (MMOs) have been widely used as CER catalysts, they suffer from the concomitant generation of oxygen during the CER. Herein, we demonstrate that atomically dispersed Pt-N-4 sites doped on a carbon nanotube (Pt-1/CNT) can catalyse the CER with excellent activity and selectivity. The Pt-1/CNT catalyst shows superior CER activity to a Pt nanoparticle-based catalyst and a commercial Ru/Ir-based MMO catalyst. Notably, Pt-1/CNT exhibits near 100% CER selectivity even in acidic media, with low Cl- concentrations (0.1M), as well as in neutral media, whereas the MMO catalyst shows substantially lower CER selectivity. In situ electrochemical X-ray absorption spectroscopy reveals the direct adsorption of Cl- on Pt-N-4 sites during the CER. Density functional theory calculations suggest the PtN4C12 site as the most plausible active site structure for the CER

evaluation of antioxidant, anticancer, and anti-MRSA activity

A rhizosphere isolate Streptomyces sp. CAH29 was found to possess potent antibacterial and antifungal activity against a variety of test organisms. Based on 16S ribosomal ribonucleic acid sequence homology studies, this strain was found to be similar to Streptomyces stramineus (gene sequence similarity 99 %). The major bioactive metabolite produced by Streptomyces sp. CAH29 isolate was extracted, purified andidentified by nuclear magnetic resonance as tetrangomycin. This known anthraquinone-exhibited antimicrobial activity against Staphylococcus aureus, Streptococcus pyogenes, methicillin resistant Staphylococcus aureus and Candida albicans with inhibition zones of 14, 10, 12 and 8 mm, respectively. Docking results demonstrate that tetrangomycin has a similar mode of action and a comparable docking score to bind to the dehydrosqualene synthase (CrtM) enzyme of methicillin resistant Staphylococcus aureus compared to the current inhibitor. Hence, this suggests that tetrangomycin has a potential to be used as an anti-methicillin resistant Staphylococcus aureus agent. Tetrangomycin also showed moderate free radical scavenging activity with 1,1-diphenyl-2-picryl-hydrazil. Tetrangomycin apparently decreased all of the studied cytokine (pro-inflammatory: interleukin 1B, interleukin 2, tumor necrosis factor and interleukin L6 and anti-inflammatory: interleukin 10) expression levels at IC50 concentrations in A459 (adenocarcinomic human alveolar basal epithelial) and LNCAP (human prostate adenocarcinoma) cell lines. In addition, it reduced Caspase 8 and 3 mRNA levels in LNCAP and A549 cells. This study describes for the first time novel in vitro immunosuppressive function of tetrangomycin by reducing the transcription of cytokine genes

Effect of dihydrotestosterone on cultured human tenocytes from intact supraspinatus tendon

The role of hormones in the pathogenesis of tendinopathy is not well recognised, even though the use of anabolic steroids is correlated with a higher incidence of spontaneous tendon ruptures. The aim of this study was to investigate the effects of dihydrotestosterone (DHT) on human tenocyte cultures from the intact supraspinatus tendon of male subjects. Cultured human tenocytes were seeded into culture plates at a density of 5 x 10(4) cells per well and incubated for 24 h. Then, 10(-9) M-10(-7) M DHT or Dulbecco's modified Eagle's medium (DMEM) only (control) was added to the culture plate wells. Cell morphology assessment and cell proliferation tests were performed 48, 72 and 96 h after DHT treatment. DHT-treated tenocytes showed an increased proliferation rate at DHT concentration higher than 10(-8) M. Differences in cell numbers between control and DHT-treated cells were statistically significant (P < 0.05) after 48 and 72 h of treatment with DHT concentrations of 10(-8) and 10(-7) M. The tenocytes treated with DHT (10(-8) and 10(-7) M) became more flattened and polygonal compared to control cells that maintained their fibroblast-like appearance during the experiment at each observation time. In conclusion, in vitro, progressive increasing concentration of DHT at doses greater than 10(-8) M had direct effects on male human tenocytes, increasing cell number after 48 and 72 h of treatment, and leading to a dedifferentiated phenotype after 48 h of treatment. This effect can be important during tendon-healing and repair, when active proliferation is required. Our results represent preliminary evidence for a possible correlation between testosterone abuse and shoulder tendinopathy

Design, Mechanism of Action, Bioavailability and Therapeutic Effects of Mn Porphyrin-Based Redox Modulators

Based on aqueous redox chemistry and simple in vivo models of oxidative stress, Escherichia coli and Saccharomyces cerevisiae, the cationic Mn(III) N-substituted pyridylporphyrins (MnPs) have been identified as the most potent cellular redox modulators within the porphyrin class of drugs; their efficacy in animal models of diseases that have oxidative stress in common is based on their high ability to catalytically remove superoxide, peroxynitrite, carbonate anion radical, hypochlorite, nitric oxide, lipid peroxyl and alkoxyl radicals, thus suppressing the primary oxidative event. While doing so MnPs could couple with cellular reductants and redox-active proteins. Reactive species are widely accepted as regulators of cellular transcriptional activity: minute, nanomolar levels are essential for normal cell function, while submicromolar or micromolar levels impose oxidative stress, which is evidenced in increased inflammatory and immune responses. By removing reactive species, MnPs affect redox-based cellular transcriptional activity and consequently secondary oxidative stress, and in turn inflammatory processes. The equal ability to reduce and oxidize superoxide during the dismutation process and recently accumulated results suggest that pro-oxidative actions of MnPs may also contribute to their therapeutic effects. All our data identify the superoxide dismutase-like activity, estimated by log k(cat)(O(2)(–)), as a good measure for the therapeutic efficacy of MnPs. Their accumulation in mitochondria and their ability to cross the blood-brain barrier contribute to their remarkable efficacy. We summarize herein the therapeutic effects of MnPs in cancer, central nervous system injuries, diabetes, their radioprotective action and potential for imaging. Few of the most potent modulators of cellular redox-based pathways, MnTE2-PyP(5+), MnTDE-2-ImP(5+), MnTnHex-2-PyP(5+) and MnTnBuOE-2-PyP(5+), are under preclinical and clinical development