對特辛基酚誘導金魚藻氧化逆境之研究

烷基酚聚氧乙烯醚 (APEOs) 屬介面活性劑，廣泛使用於各種工業與生活用品中，當排放入環境中會降解成具內分泌干擾特性之毒性代謝物，例如辛基酚、壬基酚，而對特辛基酚為已知普遍並穩定存在環境中之汙染物。為了探討對特辛基酚對水生植物的影響，本研究選用沉水植物金魚藻進行不同濃度 (0、0.5、1、1.5、 2與 3 mg/L) 對特辛基酚為期五天的試驗處理。對特辛基酚之毒性造成金魚藻成長之抑制、葉綠素含量下降並使活性氧族 (超氧陰離子、過氧化氫) 含量上升，顯示對特辛基酚毒性造成金魚藻之氧化逆境，然而MDA含量卻沒有顯著變化。抗氧化酵素活性方面，超氧化物歧化酶 (SOD)、愈創木酚過氧化物酶 (POD)、過氧化氫酶 (CAT)、穀胱甘肽還原酶 (GR) 和抗壞血酸過氧化物酶 (APX) 的活性均受對特辛基酚處理下而顯著上升；抗氧化物質方面，抗壞血酸 (AsA) 和穀胱甘肽 (GSH) 的含量也顯著增加，尤其是GSH含量尤為顯著。為了確認穀胱甘肽在金魚藻抵抗對特辛基酚所誘導之氧化逆境下所扮演之角色，試驗使用GSH生合成抑制劑 (BSO) 進行驗證。結果發現，使用BSO預處理後，金魚藻體內總GSH含量顯著降低，並伴隨著總AsA含量的降低，甚至GR和APX活性亦顯著下降，因而導致金魚藻在經過BSO預處理後暴露於對特辛基酚表現出更嚴重之氧化傷害。因此，金魚藻透過快速調節本身抗氧化系統，特別是穀胱甘肽的生合成，以抵抗對特辛基酚所誘導之氧化逆境。

關鍵字

對特辛基酚；金魚藻；氧化逆境；活性氧族；穀胱甘肽

並列摘要

Alkylphenol ethoxylates (APEOs) are surfactants which have been widely used in a variety of commercial products and can be degraded in the aquatic environment becoming more toxic metabolites. 4-tert-octylphenol (OP) is one of the primary breakdown products of APEOs with endocrine disrupting properties that has been known as persistent and ubiquitos pollutant. In order to investigate the effect of OP toxicity to aquatic plant, the submersed macrophyte Ceratophyllum demersum was chosen to treat with various concentrations of OP (0, 0.5, 1, 1.5, 2 and 3 mg L-1) for 5 days. The toxic effect and oxidative stress caused by OP resulted in an inhibition of growth rate, reduction of total chlorophyll content (chlorophyll a and b) and an increase in the levels of reactive oxygen species (ROS), O2•− and H2O2. However, there was no significant change in the content of malondialdehyde (MDA). The antioxidative enzyme activities showed a significant increase in superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), gluthathione reductase (GR) and ascorbate peroxidase (APX). The contents of non-enzymatic antioxidants, ascorbate (AsA) and glutathione (GSH), were also significantly increased under OP exposure. To confirm the role of GSH in C. demersum under OP exposure, BSO, a specific and potent inhibitor of GSH biosynthesis, was used. After BSO pretreatment, the total GSH content was significantly reduced. The decreasing of total GSH indicated that the synthesis of GSH has been blocked, it was followed by the decreasing of total AsA content and also GR and APX enzyme activity. Interestingly, C. demersum showed much more severe phenotype under OP exposure with BSO pretreatment. In conclusion, C. demersum might actively regulate the antioxidant machinery, especially GSH biosynthesis, to against OP-induced oxidative stress.

並列關鍵字

4-tert-octylphenol ； Ceratophyllum demersum ； oxidative stress ； ROS ； GSH

參考文獻

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對特辛基酚誘導金魚藻氧化逆境之研究

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