Synthesis of methylated quercetin analogues for enhancement of radical-scavenging activity
| Autor: | Takuya Arai, Kiyoshi Fukuhara, Kohei Imai, Ikuo Nakanishi, Mirei Mizuno, Ken-ichiro Matsumoto, Yusuke Ohba, Shunichi Fukuzumi, Kei Ohkubo |
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| Rok vydání: | 2017 |
| Předmět: |
Catechol
010405 organic chemistry Stereochemistry General Chemical Engineering Radical General Chemistry 010402 general chemistry 01 natural sciences 0104 chemical sciences chemistry.chemical_compound Electron transfer Radical ion chemistry Moiety Molecule heterocyclic compounds Quercetin Methyl group |
| Zdroj: | RSC Advances. 7:17968-17979 |
| ISSN: | 2046-2069 |
| DOI: | 10.1039/c7ra02329d |
| Popis: | Three quercetin derivatives with enhanced radical-scavenging activity were designed and synthesised. Because the radical-scavenging reaction of quercetin is known to proceed via an electron transfer from quercetin to radicals, producing the corresponding quercetin radical cation intermediate, the introduction of electron-donating groups into the quercetin molecule is expected to enhance its radical-scavenging activity. Thus, methyl groups were introduced into the catechol moiety in the quercetin molecule at either the 2′- or 5′-position, or both. All three quercetin analogues were found to exhibit higher radical-scavenging activity than the parent quercetin. The activity of 5′-methylquercetin is the highest among the three analogues. The optimised structure of 5′-methylquercetin calculated by density functional theory demonstrated a coplanar structure between the 4H-curomen (AC rings) and catechol (B ring) moieties, while dimethylquercetin and 2′-methylquercetin have a twisted structure between the AC and B rings. These results demonstrate that the highest radical-scavenging activity of 5′-methylquercetin is due to the stabilisation of the radical cation intermediate by the electron-donating effect of the methyl group as well as by the planar structure of the molecule. |
| Databáze: | OpenAIRE |
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