{"created":"2023-05-15T14:47:01.137457+00:00","id":64495,"links":{},"metadata":{"_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":["10:29"]},"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 (–)-epicatechin in various solvents.  \n    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.","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"],"pubdate":{"attribute_name":"公開日","attribute_value":"2012-02-13"},"publish_date":"2012-02-13","publish_status":"0","recid":"64495","relation_version_is_last":true,"title":["Solvent effects on the galvinoxyl radical-scavenging dynamics of catechins"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-05-15T21:10:57.686975+00:00"}