Proteases encoded by SARS-CoV-2 constitute a promising target for new therapies against COVID-19. SARS-CoV-2 main protease (Mpro, 3CLpro) and papain-like protease (PLpro) are responsible for viral polyprotein cleavage - a process crucial for viral survival and replication. Recently it was shown that 2-phenylbenzisoselenazol-3(2H)-one (ebselen), an organoselenium anti-inflammatory small-molecule drug, is a potent, covalent inhibitor of both the proteases and its potency was evaluated in enzymatic and anti-viral assays. In this study, we screened a collection of 23 ebselen derivatives for SARS-CoV-2 PLpro and Mpro inhibitors. Our studies revealed that ebselen derivatives are potent inhibitors of both the proteases. We identified three PLpro and four Mpro inhibitors superior to ebselen. Our work shows that ebselen constitutes a promising platform for development of new antiviral agents targeting both SARS-CoV-2 PLpro and Mpro.
Scutellaria baicalensis Georgi. (SB) is a common heat-clearing medicine in traditional Chinese medicine (TCM). It has been used for thousands of years in China and its neighboring countries. Clinically, it is mostly used to treat diseases such as cold and cough. SB has different harvesting periods and processed products for different clinical symptoms. Botanical researches proved that SB included in the Chinese Pharmacopoeia (1st, 2020) was consistent with the medicinal SB described in ancient books. Modern phytochemical analysis had found that SB contains hundreds of active ingredients, of which flavonoids are its major components. These chemical components are the material basis for SB to exert pharmacological effects. Pharmacological studies had shown that SB has a wide range of pharmacological activities such as antiinflammatory, antibacterial, antiviral, anticancer, liver protection, etc. The active ingredients of SB were mostly distributed in liver and kidney, and couldn't be absorbed into brain via oral absorption. SB’s toxicity was mostly manifested in liver fibrosis and allergic reactions, mainly caused by baicalin. The non-medicinal application prospects of SB were broad, such as antibacterial plastics, UV-resistant silk, animal feed, etc. In response to the Coronavirus Disease In 2019 (COVID-19), based on the network pharmacology research, SB’s active ingredients may have potential therapeutic effects, such as baicalin and baicalein. Therefore, the exact therapeutic effects are still need to be determined in clinical trials. SB has been reviewed in the past 2 years, but the content of these articles were not comprehensive and accurate. In view of the above, we made a comprehensive overview of the research progress of SB, and expect to provide ideas for the follow-up study of SB.
Lipopolysaccharide (LPS)-induced oxidative stress is a main feature observed in the sepsis by increasing endothelial oxidative damage. Many studies have demonstrated that Ulinastatin (UTI) can inhibit pro-inflammatory proteases, decrease inflammatory cytokine levels and suppress oxidative stress. However, the potential molecular mechanism underlying UTI which exerts its antioxidant effect is not well understood. In this study, we aimed to investigate the effects of UTI on the LPS-induced oxidative stress and the underlying mechanisms using human umbilical vein endothelial cells (HUVECs). After oxidative stress induced By LPS in HUVECs, the cell viability and reactive oxygen species (ROS) in cytoplasm were measured. In addition, superoxide dismutase (SOD) and malondialdehyde (MDA) were examined. We found that LPS resulted in a profound elevation of ROS production and MDA levels. The decrease in Cu/Zn-SOD protein and increased in Mn-SOD protein were observed in a time- and dose-dependent manner. These responses were suppressed by an addition of UTI. The increase in c-Jun N-terminal kinases (JNK) phosphorylation by LPS in HUVECs was markedly blocked by UTI or JNK inhibitor SP600125. Our results suggest that UTI exerts its anti-oxidant effects by decreasing overproduction of ROS induced by LPS via suppressing JNK/c-Jun phosphorylation. Therefore UTI may play a protective role in vascular endothelial injury induced by oxidative stress such as sepsis. This study may provide insight into a possible molecular mechanism by which Ulinastatin inhibits LPS-induced oxidative stress.
Mitochondrial glycerol 3‐phosphate dehydrogenase (mGPDH) is an integral component of the respiratory chain, and recent studies have suggested that it plays an important role in hepatic glucose homeostasis. However, its function in hepatic lipid metabolism is unclear. Here, we identified a role for mGPDH in nonalcoholic fatty liver disease (NAFLD). Specifically, mGPDH expression and activity were lower in fatty livers from patients and mice with NAFLD (ob/ob, high‐fat diet [HFD] and db/db). Liver‐specific depletion of mGPDH in mice or mGPDH knockdown in cultured hepatocytes exacerbated diet‐induced triglyceride accumulation and steatosis through enhanced lipogenesis. RNA‐sequencing revealed that mGPDH regulated endoplasmic reticulum (ER)‐related proteins and processes. mGPDH deletion exacerbated tunicamycin (ER stress inducer)‐induced hepatic steatosis, whereas tauroursodeoxycholic acid (ER stress inhibitor) rescued mGPDH depletion–induced steatosis on an HFD. Moreover, ER stress induced by mGPDH depletion could be abrogated by the intracellular Ca2+ chelator 1,2‐bis (2‐aminophenoxy) ethane N,N,N´,N´‐tetraacetic acid acetoxymethyl ester, mitochondrial permeability transition pore (mPTP) inhibitor cyclosporine A, or cyclophilin‐D (Cyp‐D) knockdown. mGPDH promoting Cyp‐D ubiquitination was also observed. Finally, liver‐specific mGPDH overexpression attenuated hepatic steatosis in ob/ob and HFD mice. Conclusion: mGPDH is a pivotal regulator of hepatic lipid metabolism. Its deficiency induces ER stress by suppressing Cyp‐D ubiquitination, a key regulator of the mitochondrial Ca2+ conductance channel mPTP, and results in hepatic steatosis. mGPDH may be a potential therapeutic target for the treatment of NAFLD.
A newly designed and fabricated electrode with three-dimensional structures is reported. The electrode consists of a conducting nanoarray substrate and Pd nanoparticles. The substrate is an array of TiO 2 nanowires with a carbon coating layer prepared via a thermal evaporation method. Pd nanoparticles were electro-deposited on the substrate surfaces by the potentiostatic pulse method. The morphology of the electrode is observed by scanning electron microscopy and transmission electron microscopy, and its structure is analyzed using an X-ray diffractometer. The catalytic performance is evaluated by cyclic voltammetry and chronoamperometry. The electrode exhibited excellent catalytic performance for NaBH 4 electro-oxidation. The current density for NaBH 4 electro-oxidation at the electrode reported in this work (524 mA mg À1 ) is about 5 times of that at conventional Pd/C (100 mA mg À1 ). This enhanced performance is likely to be due to the improved mass transport of NaBH 4 , good electronic conductivity and high Pd utilization of the electrode.
Isomaltulose is mainly produced from sucrose by microbial fermentation, when the utilization of sucrose contributes a high production cost. To achieve a low-cost isomaltulose production, soy molasses was introduced as an alternative substrate. Firstly, α-galactosidase gene from Rhizomucor miehei was expressed in Yarrowia lipolytica, which then showed a galactosidase activity of 121.6 U/mL. Under the effects of the recombinant α-galactosidase, most of the raffinose-family oligosaccharides in soy molasses were hydrolyzed into sucrose. Then the soy molasses hydrolysate with high sucrose content (22.04%, w/w) was supplemented into the medium, with an isomaltulose production of 209.4 g/L, and the yield of 0.95 g/g. Finally, by virtue of the bioremoval process using Pichia stipitis, sugar byproducts in broth were transformed into ethanol at the end of fermentation, thus resulting in high isomaltulose purity (97.8%). The bioprocess employed in this study provides a novel strategy for low-cost and efficient isomaltulose production from soybean molasses.
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