WEKO3
アイテム
{"_buckets": {"deposit": "b46e0662-ba5c-4479-be0b-b320a0782912"}, "_deposit": {"created_by": 1, "id": "64495", "owners": [1], "pid": {"revision_id": 0, "type": "depid", "value": "64495"}, "status": "published"}, "_oai": {"id": "oai:repo.qst.go.jp:00064495", "sets": ["29"]}, "author_link": ["635745", "635751", "635743", "635750", "635748", "635747", "635749", "635746", "635752", "635742", "635744"], "item_10005_date_7": {"attribute_name": "発表年月日", "attribute_value_mlt": [{"subitem_date_issued_datetime": "2012-02-04", "subitem_date_issued_type": "Issued"}]}, "item_10005_description_5": {"attribute_name": "抄録", "attribute_value_mlt": [{"subitem_description": "It is known that there are three mechanisms for the radical-scavenging reactions of phenolic compounds, such as tocopherol and (+)-catechin, i.e., one-step hydrogen-atom transfer (HAT) from the phenolic OH group to radicals, electron transfer from phenolic compounds to radicals followed by proton transfer (ET-PT), and sequential proton-loss electron transfer (SPLET). The scavenging reaction of galvinoxyl radical, used as a reactive oxygen-centered radical model, by catechin was reported to proceed via ET-PT. Although, three mechanisms of radical scavenging are known to be controlled by solvents, there are few reports on the solvent effect on the radical-scavenging mechanisms of catechins. We report herein the kinetics and mechanism of the radical-scavenging reaction by (+)-catechin and (\u0026#8211;)-epicatechin in various solvents. \n The UV-vis absorption change was monitored after mixing of deaerated acetonitrile (MeCN) solutions of galvinoxyl radical (GO\u0026#8226;), as a stable model of reactive oxygen species, and (+)-catechin using the stopped-flow technique. The radical-scavenging rate constants (k) of (+)-catechin and (-)-epicatechin were determined to be 6.1 x 10 and 1.1 x 102 M-1 s-1, respectively. No effect of acetic acid (CH3COOH) on the GO-scavenging reaction by catechins indicates that these scavenging reactions proceed via ET-PT. In methanol (MeOH), the pseudo-first order rate constant (kobs) for (+)-catechin increased with increasing concentration of (+)-catechin and reached a constant value. In the case of (-)-epicatechin, the kobs value was increased linearly with an increase in concentration of (-)-epicatechin. When CH3COOH was added to the reaction solutions in order to inhibit the deprotonation of catechins in MeOH, the k values of catechins were significantly decreased. The effect of CH3COOH on the k values was also observed in ethanol (EtOH). These results suggest that the GO\u0026#8226;-scavenging reaction by catechins may proceed via the SPLET mechanism in protic media, such as MeOH and EtOH.", "subitem_description_type": "Abstract"}]}, "item_10005_description_6": {"attribute_name": "会議概要(会議名, 開催地, 会期, 主催者等)", "attribute_value_mlt": [{"subitem_description": "第19回日本学術振興会先端研究拠点事業セミナー:Winter School in Fukuoka 2012", "subitem_description_type": "Other"}]}, "item_access_right": {"attribute_name": "アクセス権", "attribute_value_mlt": [{"subitem_access_right": "metadata only access", "subitem_access_right_uri": "http://purl.org/coar/access_right/c_14cb"}]}, "item_creator": {"attribute_name": "著者", "attribute_type": "creator", "attribute_value_mlt": [{"creatorNames": [{"creatorName": "Kawashima, Tomonori"}], "nameIdentifiers": [{"nameIdentifier": "635742", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "Nakanishi, Ikuo"}], "nameIdentifiers": [{"nameIdentifier": "635743", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "Imai, Kohei"}], "nameIdentifiers": [{"nameIdentifier": "635744", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "Ohkubo, Kei"}], "nameIdentifiers": [{"nameIdentifier": "635745", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "Fukuhara, Kiyoshi"}], "nameIdentifiers": [{"nameIdentifier": "635746", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "Fukuzumi, Shunichi"}], "nameIdentifiers": [{"nameIdentifier": "635747", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "Matsumoto, Kenichiro"}], "nameIdentifiers": [{"nameIdentifier": "635748", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "川島 知憲", "creatorNameLang": "en"}], "nameIdentifiers": [{"nameIdentifier": "635749", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "中西 郁夫", "creatorNameLang": "en"}], "nameIdentifiers": [{"nameIdentifier": "635750", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "今井 耕平", "creatorNameLang": "en"}], "nameIdentifiers": [{"nameIdentifier": "635751", "nameIdentifierScheme": "WEKO"}]}, {"creatorNames": [{"creatorName": "松本 謙一郎", "creatorNameLang": "en"}], "nameIdentifiers": [{"nameIdentifier": "635752", "nameIdentifierScheme": "WEKO"}]}]}, "item_language": {"attribute_name": "言語", "attribute_value_mlt": [{"subitem_language": "eng"}]}, "item_resource_type": {"attribute_name": "資源タイプ", "attribute_value_mlt": [{"resourcetype": "conference object", "resourceuri": "http://purl.org/coar/resource_type/c_c94f"}]}, "item_title": "Solvent effects on the galvinoxyl radical-scavenging dynamics of catechins", "item_titles": {"attribute_name": "タイトル", "attribute_value_mlt": [{"subitem_title": "Solvent effects on the galvinoxyl radical-scavenging dynamics of catechins"}]}, "item_type_id": "10005", "owner": "1", "path": ["29"], "permalink_uri": "https://repo.qst.go.jp/records/64495", "pubdate": {"attribute_name": "公開日", "attribute_value": "2012-02-13"}, "publish_date": "2012-02-13", "publish_status": "0", "recid": "64495", "relation": {}, "relation_version_is_last": true, "title": ["Solvent effects on the galvinoxyl radical-scavenging dynamics of catechins"], "weko_shared_id": -1}
Solvent effects on the galvinoxyl radical-scavenging dynamics of catechins
https://repo.qst.go.jp/records/64495
https://repo.qst.go.jp/records/6449583557c11-55c9-4145-b437-8463114ec2e2
Item type | 会議発表用資料 / Presentation(1) | |||||
---|---|---|---|---|---|---|
公開日 | 2012-02-13 | |||||
タイトル | ||||||
タイトル | Solvent effects on the galvinoxyl radical-scavenging dynamics of catechins | |||||
言語 | ||||||
言語 | eng | |||||
資源タイプ | ||||||
資源タイプ識別子 | http://purl.org/coar/resource_type/c_c94f | |||||
資源タイプ | conference object | |||||
アクセス権 | ||||||
アクセス権 | metadata only access | |||||
アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
著者 |
Kawashima, Tomonori
× Kawashima, Tomonori× Nakanishi, Ikuo× Imai, Kohei× Ohkubo, Kei× Fukuhara, Kiyoshi× Fukuzumi, Shunichi× Matsumoto, Kenichiro× 川島 知憲× 中西 郁夫× 今井 耕平× 松本 謙一郎 |
|||||
抄録 | ||||||
内容記述タイプ | Abstract | |||||
内容記述 | It is known that there are three mechanisms for the radical-scavenging reactions of phenolic compounds, such as tocopherol and (+)-catechin, i.e., one-step hydrogen-atom transfer (HAT) from the phenolic OH group to radicals, electron transfer from phenolic compounds to radicals followed by proton transfer (ET-PT), and sequential proton-loss electron transfer (SPLET). The scavenging reaction of galvinoxyl radical, used as a reactive oxygen-centered radical model, by catechin was reported to proceed via ET-PT. Although, three mechanisms of radical scavenging are known to be controlled by solvents, there are few reports on the solvent effect on the radical-scavenging mechanisms of catechins. We report herein the kinetics and mechanism of the radical-scavenging reaction by (+)-catechin and (–)-epicatechin in various solvents. The UV-vis absorption change was monitored after mixing of deaerated acetonitrile (MeCN) solutions of galvinoxyl radical (GO•), as a stable model of reactive oxygen species, and (+)-catechin using the stopped-flow technique. The radical-scavenging rate constants (k) of (+)-catechin and (-)-epicatechin were determined to be 6.1 x 10 and 1.1 x 102 M-1 s-1, respectively. No effect of acetic acid (CH3COOH) on the GO-scavenging reaction by catechins indicates that these scavenging reactions proceed via ET-PT. In methanol (MeOH), the pseudo-first order rate constant (kobs) for (+)-catechin increased with increasing concentration of (+)-catechin and reached a constant value. In the case of (-)-epicatechin, the kobs value was increased linearly with an increase in concentration of (-)-epicatechin. When CH3COOH was added to the reaction solutions in order to inhibit the deprotonation of catechins in MeOH, the k values of catechins were significantly decreased. The effect of CH3COOH on the k values was also observed in ethanol (EtOH). These results suggest that the GO•-scavenging reaction by catechins may proceed via the SPLET mechanism in protic media, such as MeOH and EtOH. |
|||||
会議概要(会議名, 開催地, 会期, 主催者等) | ||||||
内容記述タイプ | Other | |||||
内容記述 | 第19回日本学術振興会先端研究拠点事業セミナー:Winter School in Fukuoka 2012 | |||||
発表年月日 | ||||||
日付 | 2012-02-04 | |||||
日付タイプ | Issued |