{"created":"2023-05-15T14:51:32.024108+00:00","id":70445,"links":{},"metadata":{"_buckets":{"deposit":"ac8b8658-2cef-4f2f-89b3-636eaaebfbb4"},"_deposit":{"created_by":1,"id":"70445","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"70445"},"status":"published"},"_oai":{"id":"oai:repo.qst.go.jp:00070445","sets":["10:28"]},"author_link":["691759","691768","691765","691760","691758","691757","691767","691756","691762","691769","691761","691764","691766","691763"],"item_10005_date_7":{"attribute_name":"発表年月日","attribute_value_mlt":[{"subitem_date_issued_datetime":"2011-05-31","subitem_date_issued_type":"Issued"}]},"item_10005_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"Melatonin (N-acetyl-5-methoxytryptamine), a pineal hormone, is known to show efficient antioxidative and radioprotective activities.  Recently, we have reported that galvinoxyl raidcal (GO) used as a model of reactive oxygen radical was scavenged by melatonin in methanol (MeOH).  However, the detailed molecular mechanism for the radical-scavenging reaction of melatonin has yet to be fully clarified.  In this study, we explored the effect of a metal ion on the radical-scavenging rates of melatonin in order to clarify the involvement of the electron-transfer process, which is known to be accelerated in the presence of redox inactive metal ions.\nUpon addition of GO to a MeOH solution of melatonin at 298 K, the absorption band at 428 nm due to Go gradually decreased.  The decay of the absorbance at 428 nm obeyed pseudo-first-order kinetics, when the concentration of melatonin ([melatonin]) was maintained at more than 10-fold excess of the GO concentration.  The observed pseudo-first-order rate constant (kobs) increases linearly with increasing the melatonin concentration.  From the slope of the linear plot of kobs vs [melatonin] is determined the second-order rate constant (k) for the GO-scavenging reaction of melatonin to be 6.4 x 10(-2) M(-1) s(-1) in MeOH at 298 K.  When Mg(ClO4)2 (0.1 M) was added to the melatonin-GO system in MeOH, the k value was significantly increased (k = 1.4 x 10(-1) M(-1) s(-1)).  Such an acceleration in the presence of the metal ion suggests that the GO-scavenging reaction of melatonin proceeds via  a  proton-coupled electron transfer rather than via a one-step hydrogen atom transfer.  Similar results were obtained when GO was replaced by 2,2-diphyenyl-1-picrylhydrazyl radical (DPPH).  No radical-scavenging was observed when melatonin was replaced by N-methylmelatonin, suggesting that the deprotonation of the N-H hydrogen may be responsible for the radical-scavenging activity of melatonin.  The kinetic data together with the one-electron oxidation potential determined by the second-harmonic alternating current voltammetry (SHACV) as well as calculated thermodynamic parameters by the density functional theory (DFT) obtained in this study provide a detailed mechanistic insight into the antioxidative and radioprotective activities of melatonin.","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21回金属の関与する生体関連反応シンポジウム","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":"中西, 郁夫"}],"nameIdentifiers":[{"nameIdentifier":"691756","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"カビル, ゾーダー"}],"nameIdentifiers":[{"nameIdentifier":"691757","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"川島, 知憲"}],"nameIdentifiers":[{"nameIdentifier":"691758","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"上林, 將人"}],"nameIdentifiers":[{"nameIdentifier":"691759","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"松本, 謙一郎"}],"nameIdentifiers":[{"nameIdentifier":"691760","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"大久保, 敬"}],"nameIdentifiers":[{"nameIdentifier":"691761","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"福住, 俊一"}],"nameIdentifiers":[{"nameIdentifier":"691762","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"安西, 和紀"}],"nameIdentifiers":[{"nameIdentifier":"691763","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"小澤, 俊彦"}],"nameIdentifiers":[{"nameIdentifier":"691764","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"中西 郁夫","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"691765","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"カビル ゾーダー","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"691766","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"川島 知憲","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"691767","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"上林 將人","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"691768","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"松本 謙一郎","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"691769","nameIdentifierScheme":"WEKO"}]}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"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":"金属イオン存在下におけるメラトニンのラジカル消去反応","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"金属イオン存在下におけるメラトニンのラジカル消去反応"}]},"item_type_id":"10005","owner":"1","path":["28"],"pubdate":{"attribute_name":"公開日","attribute_value":"2011-06-01"},"publish_date":"2011-06-01","publish_status":"0","recid":"70445","relation_version_is_last":true,"title":["金属イオン存在下におけるメラトニンのラジカル消去反応"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-05-15T20:02:52.676684+00:00"}