A novel type of polymer nanocomposite (NC) hydrogel with extraordinary mechanical properties at low inorganic content is prepared and investigated. The NC hydrogels consist of isethionate-loaded layered double hydroxide/polyacrylamide (LDH-Ise/PAM) - with LDH-Ise being used because of its swelling properties - and no conventional organic crosslinker. The NC hydrogels exhibit an unusual hierarchical porous structure at the micro- and nanometer scales, and their elongation at break can exceed 4000%.
Context:Scutellaria baicalensis Georgi (Lamiaceae) is a popular medicinal plant. Its roots are used as the famous traditional Chinese medicine Huang-Qin, which is recorded in Chinese Pharmacopoeia, European Pharmacopoeia, and British Pharmacopoeia.Objective: This review comprehensively summarizes research progress in phytochemistry, pharmacology, and flavonoid biosynthesis of S. baicalensis.Methods: English and Chinese literature from 1973 to March 2018 was collected from databases including Web of Science, SciFinder, PubMed, Elsevier, Baidu Scholar (Chinese), and CNKI (Chinese). Scutellaria baicalensis, chemical constituents, phytochemistry, biological activities, and biosynthesis were used as the key words.Results: A total of 126 small molecules (1–126) and 6 polysaccharides have been isolated from S. baicalensis. The small molecules can be classified into four structural types, namely, free flavonoids, flavonoid glycosides, phenylethanoid glycosides, and other small molecules. Extracts of S. baicalensis and its major chemical constituents have been reported to possess anti-viral, anti-tumor, anti-bacterial, antioxidant, anti-inflammatory, hepatoprotective, and neuroprotective activities. Key steps in the biosynthetic pathways of Scutellaria flavonoids have also been summarized.Conclusions: This article could be helpful for researchers who are interested in the chemical constituents, bioactivities, biosynthesis, and clinical applications of S. baicalensis.
Herein, the catalytic promiscuity of TcCGT1, a new C‐glycosyltransferase (CGT) from the medicinal plant Trollius chinensis is explored. TcCGT1 could efficiently and regio‐specifically catalyze the 8‐C‐glycosylation of 36 flavones and other flavonoids and could also catalyze the O‐glycosylation of diverse phenolics. The crystal structure of TcCGT1 in complex with uridine diphosphate was determined at 1.85 Å resolution. Molecular docking revealed a new model for the catalytic mechanism of TcCGT1, which is initiated by the spontaneous deprotonation of the substrate. The spacious binding pocket explains the substrate promiscuity, and the binding pose of the substrate determines C‐ or O‐glycosylation activity. Site‐directed mutagenesis at two residues (I94E and G284K) switched C‐ to O‐glycosylation. TcCGT1 is the first plant CGT with a crystal structure and the first flavone 8‐C‐glycosyltransferase described. This provides a basis for designing efficient glycosylation biocatalysts.
The RIG-I-like RNA helicase (RLR)-mediated interferon (IFN) response plays a pivotal role in the hepatic antiviral immunity. The hepatitis A virus (HAV) and the hepatitis C virus (HCV) counter this response by encoding a viral protease that cleaves the mitochondria antiviral signaling protein (MAVS), a common signaling adaptor for RLRs. However, a third hepatotropic RNA virus, the hepatitis E virus (HEV), does not appear to encode a functional protease yet persists in infected cells. We investigated HEV-induced IFN responses in human hepatoma cells and primary human hepatocytes. HEV infection resulted in persistent virus replication despite poor spread. This was companied by a type III IFN response that upregulated multiple IFN-stimulated genes (ISGs), but type I IFNs were barely detected. Blocking type III IFN production or signaling resulted in reduced ISG expression and enhanced HEV replication. Unlike HAV and HCV, HEV did not cleave MAVS; MAVS protein size, mitochondrial localization, and function remained unaltered in HEV-replicating cells. Depletion of MAVS or MDA5, and to a less extent RIG-I, also diminished IFN production and increased HEV replication. Furthermore, persistent activation of the JAK/STAT signaling rendered infected cells refractory to exogenous IFN treatment, and depletion of MAVS or the receptor for type III IFNs restored the IFN responsiveness. Collectively, these results indicate that unlike other hepatotropic RNA viruses, HEV does not target MAVS and its persistence is associated with continuous production of type III IFNs.
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