花生四烯酸對人類血小板所產生氫氧自由基之探討

Mechanisms Involved in Arachidonic Acid-Induced Hydroxyl Radical Formation in Human Platelets.

黃淑姿(Su-Tzy Hwang)

指導教授 ： 周敦穗

共同指導教授 ： 許準榕(Joen-Rong Sheu)

臺北醫學大學/醫學院/醫學科學研究所/碩士(2008年)

https://doi.org/10.6831/TMU.2008.00038

摘要

過去由Daljeet et al等人使用14CO2 quantification 技術研究指出，花生四烯酸能使血小板產生氫氧自由基，但其使用的是間接的方法測定自由基的含量。因此本實驗的目的是以直接的方式─電子順磁共振儀 (ESR) 測定花生四烯酸是否能使血小板產生氫氧自由基，並進一步探討其詳細機制。在初步實驗中，於電子順磁共振 (ESR) 中，以DMPO (5,5-dimethyl-1-pyrrolin-N-oxide)當補捉自由基試劑，我們發現低濃度花生四烯酸會促進血小板產生氫氧自由基。花生四烯酸的代謝有三種途徑可能產生氫氧自由基，即Lipoxygenase，Cyclooxygenase，NADPH oxidase之路徑。本實驗進一步探討發現低濃度花生四烯酸在血小板中產生的氫氧自由基是經由12-lipoxygenase pathway而來的。除此之外，本實驗還以此一系統測試一些天然抗氧化物例如：resveratrol, rutin, quercetin，及lycopene等。研究顯示能有效地清除低濃度花生四烯酸促進血小板產生的氫氧自由基。然而我們發現當12-lipoxygenase被抑制時，會產生另一種自由基為g = 2.006 自由基，此自由基的產生是因高濃度的peroxides使得中間自由基產物的累積，進而產生自我的摧毀現象。因此，我們認為此一系統可成為新的包含細胞的抗氧化實驗模式。

關鍵字

花生四烯酸 ； 氫氧自由基 ； 血小板 ； 12-脂肪氧化酶g = 2.006自由基

並列摘要

Previously Daljeet et al, using a 14CO2 quantification method, have demonstrated the generation of hydroxyl radical by arachidonic acid (AA) in platelets. In experiment, we detected a hydroxyl radical signal induced by AA by electron spin resonance (ESR) techniques in using spin traps such as DMPO (5,5-dimethyl-1-pyrroline-N-oxide). Three mechanisms have been proposed to the generation of hydroxyl radical by AA: lipoxygenase, cyclooxygenase, and NADPH oxidase. We proposed that blood platelets can produce hydroxyl radical when reacting with AA via 12-lipoxygenase pathway. In addition, we examine the free radical scavenger activity of some natural products such as resvertrol, rutin, quercetin, and lycopene by using this experiment system. Our results showed that AA induced hydroxyl radical formation was inhibited by these antioxidants. Finally, we’ve found g = 2.006 radical generation due to inhibit 12-lipoxygenase activity, leading to produce self-destructive species in accumulation of intermediate I, II at highly concentration of peroxides. In this study, we attempted to directly detect and identify free radicals formed from AA in human platelets and investigate the precise mechanisms. We suggest that this cell-containing system can be a new antioxidant experimental model.

並列關鍵字

Arachidonic acid ； hydroxyl radical ； platelets ； 12-lipoxygenase ； g = 2.006 radical

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