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RISS 인기검색어
- 검색키워드
- 주제어 : Hydrogen atom transfer (검색결과 4 건)
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최종근 한국산학기술학회 2024 한국산학기술학회논문지 Vol.25 No.2
Nyasol is a lignan isolated from Anemarrhena asphodeloides Bunge with potent anti-tyrosinase, antipyretic, cardiotonic, diuretic, antibacterial, and antioxidant activities. In this study, theoretical calculations based on density functional theory (DFT) using the B3LYP hybrid functional and the 6-311+G(d,p) basis sets were conducted to explain the antioxidant behavior of nyasol. After twenty-four initial structures had been generated by Omega2 and optimized by Gaussian 16, three distinct conformers were selected for further calculations. Electronic property results showed that nyasol has radical scavenging activity and that 4’-OH is more potent than 4-OH. However, nyasol has weaker radical scavenging activity than well-known antioxidants. And, the results obtained by calculation agreed with published experimental data. In addition, three different mechanisms for the antioxidant effect of nyasol, viz., hydrogen atom transfer (HAT), single electron transfer-proton transfer (SETPT), and sequential proton loss electron transfer (SPLET), were studied and compared in the gas phase and ethanol and water medium. The results obtained showed HAT was thermodynamically dominant.
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Yoon, Ung-Chan,Oh, Sun-Wha,Moon, Seong-Chul,Hyung, Tae-Gyung Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.1
Studies have been conducted to explore photoaddition reactions of N-methylthiophthalimide with $\alpha$-silyl-n-electron donors Et$_2$NCH$_2$SiMe$_3$, n-PrSCH$_2$SiMe$_3$ and EtOCH$_2$SiMe$_3$. Photoaddition of $\alpha$-silyl amine Et$_2$NCH$_2$SiMe$_3$ to N-methylthiophthalimide occurs in $CH_3$CN and benzene to produce non-silicon containing adduct in which thiophthalimide thione carbon is bonded to $\alpha$-carbon of $\alpha$-silyl amine in place of the trimethylsilyl group. In contrast, photoaddition of EtOCH$_2$SiMe$_3$ to N-methylthiophthalimide generates two diastereomeric adducts in which thiophthalimide thione carbon is connected to $\alpha$-carbon of $\alpha$-silyl ether in place of u-hydrogen. Based on a consideration of the oxidation potentials of u-silyl-n-electron donors and the nature of photoadducts, mechanism for these photoadditions involving single electron transfer(SET) -desilylation and H atom abstraction pathways are proposed.
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Jing Lin,Xican Li,Li Chen,Weizhao Lu,Xianwen Chen,Lu Han,Dongfeng Chen 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.6
[6]-Gingerol is known as the major bioactive constituent of ginger. In the study, it was observed to effectively protect against •OH-induced DNA damage (IC50 328.60 ± 24.41 μM). Antioxidant assays indicated that [6]- gingerol could efficiently scavenge various free radicals, including •OH radical (IC50 70.39 ± 1.23 μM), •O2 − radical (IC50 228.40 ± 9.20 μM), DPPH• radical (IC50 27.35 ± 1.44 μM), and ABTS+• radical (IC50 2.53 ± 0.070 μM), and reduce Cu2+ ion (IC50 11.97 ± 0.68 μM). In order to investigate the possible mechanism, the reaction product of [6]-gingerol and DPPH• radical was further measured using HPLC combined mass spectrometry. The product showed a molecular ion peak at m/z 316 [M+Na]+, and diagnostic fragment loss (m/z 28) for quinone. On this basis, it can be concluded that: (i) [6]-gingerol can effectively protect against •OH-induced DNA damage; (ii) a possible mechanism for [6]-gingerol to protect against oxidative damage is •OH radical scavenging; (iii) [6]-gingerol scavenges •OH radical through hydrogen atom (H•) transfer (HAT) and sequential electron (e) proton transfer (SEPT) mechanisms; and (iv) both mechanisms make [6]-gingerol be oxidized to semi-quinone or quinone forms.
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Lin, Jing,Li, Xican,Chen, Li,Lu, Weizhao,Chen, Xianwen,Han, Lu,Chen, Dongfeng Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.6
[6]-Gingerol is known as the major bioactive constituent of ginger. In the study, it was observed to effectively protect against ${\bullet}OH$-induced DNA damage ($IC_{50}$ $328.60{\pm}24.41{\mu}M$). Antioxidant assays indicated that [6]-gingerol could efficiently scavenge various free radicals, including ${\bullet}OH$ radical ($IC_{50}$ $70.39{\pm}1.23{\mu}M$), ${\bullet}O_2{^-}$ radical ($IC_{50}$ $228.40{\pm}9.20{\mu}M$), $DPPH{\bullet}$radical ($IC_{50}$ $27.35{\pm}1.44{\mu}M$), and $ABTS{^+}{\bullet}$radical ($IC_{50}$ $2.53{\pm}0.070{\mu}M$), and reduce $Cu^{2+}$ ion ($IC_{50}$ $11.97{\pm}0.68{\mu}M$). In order to investigate the possible mechanism, the reaction product of [6]-gingerol and $DPPH{\bullet}$ radical was further measured using HPLC combined mass spectrometry. The product showed a molecular ion peak at m/z 316 $[M+Na]^+$, and diagnostic fragment loss (m/z 28) for quinone. On this basis, it can be concluded that: (i) [6]-gingerol can effectively protect against ${\bullet}OH$-induced DNA damage; (ii) a possible mechanism for [6]-gingerol to protect against oxidative damage is ${\bullet}OH$ radical scavenging; (iii) [6]-gingerol scavenges ${\bullet}OH$ radical through hydrogen atom ($H{\bullet}$) transfer (HAT) and sequential electron (e) proton transfer (SEPT) mechanisms; and (iv) both mechanisms make [6]-gingerol be oxidized to semi-quinone or quinone forms.
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