MOLECULES
·
2016
·Vol. 21
·期 9
·1246
·
IF 2.465
Xican Li,Qian Jiang,Tingting Wang,Jingjing Liu,Dongfeng Chen
The role of the 6″-OH (ω-OH) group in the antioxidant activity of flavonoid glycosides has been largely overlooked. Herein, we selected quercitrin (quercetin-3-O-rhamnoside) and isoquercitrin (quercetin-3-O-glucoside) as model compounds to investigate the role of the 6″-OH group in several antioxidant pathways, including Fe2+-binding, hydrogen-donating (H-donating), and electron-transfer (ET). The results revealed that quercitrin and isoquercitrin both exhibited dose-dependent antioxidant activities. However, isoquercitrin showed higher levels of activity than quercitrin in the Fe2+-binding, ET-based ferric ion reducing antioxidant power, and multi-pathways-based superoxide anion-scavenging assays. In contrast, quercitrin exhibited greater activity than isoquercitrin in an H-donating-based 1,1-diphenyl-2-picrylhydrazyl radical-scavenging assay. Finally, in a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl assay based on an oxidatively damaged mesenchymal stem cell (MSC) model, isoquercitrin performed more effectively as a cytoprotector than quercitrin. Based on these results, we concluded that (1) quercitrin and isoquercitrin can both indirectly (i.e., Fe2+-chelating or Fe2+-binding) and directly participate in the scavenging of reactive oxygen species (ROS) to protect MSCs against ROS-induced oxidative damage; (2) the 6″-OH group in isoquercitrin enhanced its ET and Fe2+-chelating abilities and lowered its H-donating abilities via steric hindrance or H-bonding compared with quercitrin; and (3) isoquercitrin exhibited higher ROS scavenging activity than quercitrin, allowing it to improve protect MSCs against ROS-induced oxidative damage.Keywords:quercitrin;isoquercitrin;Q3G;6″-OH;ω-OH;flavonoid glycoside;antioxidant mechanisms;mesenchymal stem cells
研究领域:
药理学
·
生物化学
·
细胞生物学
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产品关联
DOI
PubMed
高影响因子
CHEMBIOCHEM
·
2022
·Vol. 23
·期 9
·e202200063
·
IF 3.461
Ya-Li Dong,Gang-Gang Chong,Chun-Xiu Li,Qi Chen,Jiang Pan,Ai-Tao Li,Jian-He Xu
Graphical Make activation of C-H bond feasible : Cytochrome P450 monooxygenases (P450s) catalyze the terminal hydroxylation of fatty acids to form ω-hydroxy fatty acids. To date, available P450s for the terminal hydroxylation of fatty acids stalls at CYP153A subfamily members, which have the limitation of low activity and poor thermostability. We, therefore, adopted directed evolution to generate P450pyr mutants with higher catalytic efficiency toward medium-chain fatty acids. The results show that mutants toward C6−C12 fatty acids display improved analytical yields of ω-hydroxy fatty acids. The P450-mediated terminal hydroxylation of non-activated C−H bonds is a chemically challenging reaction. CYP153A7 monooxygenase, discovered in Sphingomonas sp. HXN200, belongs to the CYP153A subfamily and shows a pronounced terminal selectivity. Herein, we report the significantly improved terminal hydroxylation activity of CYP153A7 by redesign of the substrate binding pocket based on molecular docking of CYP153A7−C 8:0 and sequence alignments. Some of the resultant single mutants were advantageous over the wild-type enzyme with higher reaction rates, achieving a complete conversion of n- octanoic acid (C 8:0, 1 mM) in a shorter time period. Especially, a single-mutation variant, D258E, showed 3.8-fold higher catalytic efficiency than the wild type toward the terminal hydroxylation of medium-chain fatty acid C 8:0 to the high value-added product 8-hydroxyoctanoic acid.
研究领域:
生物化学
·
酶学
·
生物催化
·
蛋白质工程
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产品关联
DOI
PubMed
高影响因子
POLYMER DEGRADATION AND STABILITY
·
2022
·
IF 5.204
Yumin Wu,Yizhi Jiao,Zhihao Rong,Chuanhui Gao,Yuetao Liu
Manufacturing organosilicon elastomers that have combined reprocessability, self-healing, and high stretchable properties, this remains a significant challenge. Herein, we proposed a simple one-pot method to synthesize thermoset organosilicon elastomers which could be self-healed and had good mechanical properties. The elastomers were capped with the α,ω-hydroxypolydimethylsiloxane and isophorone diisocyanate, following chain expansion with adipic dihydrazide, and cross-linked by triethanolamine. The average elongation of the elastomers was 1145%, with the largest strain of 4.1 MPa. Due to the highly flexible Si-O chain and the large number of hydrogen bonds formed by the dynamic acyl semicarbazide (ASC) groups, the elastomers had good self-healing ability. It was noted that the elastomers could be recycled entirely under the synergistic dynamic effect of ASC groups without chemical treatment, and the elastomers could achieve 91% of the initial mechanical strength even after ten times of dissolution recycling. And through three times of hot pressing recovery, 86% of the mechanical properties were also maintained. In addition, the self-healing flexible electronic devices were prepared by compounding multi-walled carbon nanotubes (MWCNTs), and they could monitor the subtle movements of the human body. This work fabricated the reprocessable and self-healing organosilicon elastomers for flexible electronic devices, which might have essential inspiration for the sustainable development of organosilicon materials.
研究领域:
材料科学
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聚合物化学
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柔性电子
·
可持续材料
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DOI
高影响因子
危险品化学品经营许可证（带存储）