台灣省產柳松菇水萃取物對於羥自由基造成DNA股斷裂之保護效果   全文下載

Aqueous Extract from Taiwanese Agrocybe cylindracea strain B Protects DNA against•OH- mediated Strand Breaks

先前研究得知，省產食用菇之柳松菇水萃取物（ACE）具抗氧化活性。其在體外試驗上是一種有效的抗氧化劑。由於DNA的氧化傷害與癌症的發展有密切相關，因而本文以H2O2和Cu（II）作為產生羥自由基進而造成pUC 18質體DNA和人類肝癌HepG2細胞的DNA氧化傷害，藉此探討柳松菇水萃取物對於羥自由基造成DNA股斷裂之保護效果。以超螺旋質體DNA和彗星分析法，再經洋菜瓊脂膠體電泳分析，評估DNA氧化傷害的程度是否受到柳松菇水萃取物的共存而減少。研究結果指出，在超螺旋質體DNA和彗星DNA傷害二種分析條件下，柳松菇水萃取物對於DNA受到銅離子[Cu（II）]調控性羥自由基的氧化傷害，其達半數抑制濃度分別為69.7μg／mL和91.6μg／mL。且柳松菇水萃取物的抗氧化能力均顯著高於香菇水萃取物（LEE）及已知的兩種羥自由基捕捉劑-甘露糖醇（mannitol）和thiourea。此外，對於H2O2和金屬離子產生的羥自由基所造成2'-去氧核糖的氧化性裂解作用，柳松菇和香菇水萃取物兩者亦具有抑制效果，且柳松菇水萃取物的活性蛋白區分物的抑制效果顯著高於香菇水萃取物的活性蛋白區分物，益得知柳松菇水萃取物的活性蛋白組成不同於香菇水萃取物的活性蛋白組成。

Water extract from Agrocybe cylindracea strain B (ACE), an edible mushroom produced in Taiwan, has previously been studied for its antioxidative activities. ACE is an efficient antioxidant in vitro. Since oxidative alterations of DNA can be linked to the development of cancer, we decided to study whether ACE protects DNA against oxidative stress. We report here that pUC18 plasmid DNA and HepG2 cells’ DNA are damaged by• OH radicals generated from Cu (II) plus H2O2. The DNA damage was quantified by determining the diminution of supercoiled DNA forms and the DNA migration after oxidative attack using agarose gel electrophoresis. The IC50 values of ACE were 69.7 μg/mL and 91.6 μg/mL for cupric-mediated• OH formation by determining the diminution of supercoiled DNA forms and Comet assay, respectively. The antioxidant capacity of ACE was significantly higher than that of Lentinus edodes extract (LEE) and the two known scavengers of hydroxyl radical, mannitol and thiourea. ACE and LEE could also inhibit the oxidative degradation of 2’-deoxyribose caused by• OH radicals generated from metal ions plus H2O2. The malondialdehyde (MDA) inhibition effect of active fractional protein from ACE was better than that of LEE. The major protein components of ACE were different from LEE. 先前研究得知，省產食用菇之柳松菇水萃取物（ACE）具抗氧化活性。其在體外試驗上是一種有效的抗氧化劑。由於DNA的氧化傷害與癌症的發展有密切相關，因而本文以H2O2和Cu（II）作為產生羥自由基進而造成pUC 18質體DNA和人類肝癌HepG2細胞的DNA氧化傷害，藉此探討柳松菇水萃取物對於羥自由基造成DNA股斷裂之保護效果。以超螺旋質體DNA和彗星分析法，再經洋菜瓊脂膠體電泳分析，評估DNA氧化傷害的程度是否受到柳松菇水萃取物的共存而減少。研究結果指出，在超螺旋質體DNA和彗星DNA傷害二種分析條件下，柳松菇水萃取物對於DNA受到銅離子[Cu（II）]調控性羥自由基的氧化傷害，其達半數抑制濃度分別為69.7μg／mL和91.6μg／mL。且柳松菇水萃取物的抗氧化能力均顯著高於香菇水萃取物（LEE）及已知的兩種羥自由基捕捉劑-甘露糖醇（mannitol）和thiourea。此外，對於H2O2和金屬離子產生的羥自由基所造成2'-去氧核糖的氧化性裂解作用，柳松菇和香菇水萃取物兩者亦具有抑制效果，且柳松菇水萃取物的活性蛋白區分物的抑制效果顯著高於香菇水萃取物的活性蛋白區分物，益得知柳松菇水萃取物的活性蛋白組成不同於香菇水萃取物的活性蛋白組成。