咪唑类离子液体对蚯蚓,斑马鱼和小麦的DNA损伤及对抗氧化酶系和解毒酶系的影响

Ionic liquids (ILs) are organic salts consisted entirely of ions. Because of their special physical and chemical properties including negligible vapor pressure, low melting points (<100℃) and good solubility, ILs were considered as novel green solvents and obtained rapid development in recent years. The studies of ILs which become one of the hottest areas in chemistry mainly focus on physical and chemical properties, chemical synthesis and practical application. Although ILs have a considerable technical and commercial potential, the solubility of ILs in water and their accumulation and biological toxicity to organisms have aroused wide concern among ILs researchers and will restrict the application and development of ILs. A number of researches suggested that they have obvious toxic actions on microbes, aquatic and soil organisms and particularly, their toxicity may even higher than traditional organic solvents. As a result, the knowledge of ILs behavior in the terrestrial environment is very important since both soil and aquatic milieu are possible recipients of IL contamination. Nevertheless, very few such investigations on their toxic effects have been made to date. In order to synthetically evaluate the toxic effects of ILs on organisms live in different ecosystems, the imidazolium-based ionic liquids, which are the most widely studied and applied among numerous ILs were used to estimate oxidative stress (the activity of total superoxide dismutase (SOD), catalase (CAT) and peroxidase(POD);the contents of Reactive Oxygen Species (ROS)), detoxification system (cytochrome P450 enzymes, glutathione S-transferase (GST)) and DNA damage in zebrafish (Danio rerio), earthworm (Eisenia foetida) and wheat, respectively. The toxicological studies on three international model organisms and the exploration of the relationship among these indicators may explain the mechanisms in organisms and provide a basis for the evaluation to ecological security of ILs.

离子液体作为一类新型"绿色溶剂"得到了迅猛发展,已成为化学领域的研究热点,研究主要集中在合成、理化特性和应用方面。离子液体进入环境后在生物体内的累积及对生物体的毒性等问题越来越引起人们的重视,也成为制约其发展与应用的瓶颈,但这方面的研究还非常匮乏,是环境化学领域亟待研究的问题。本课题以最常用的咪唑类离子液体为代表,选择国际通用的斑马鱼、赤子爱胜蚓和小麦分别代表水生、陆生生物和高等植物。选择SOD，POD和CAT为抗氧化酶指标,选择细胞色素P450和GST等为体内解毒酶指标,选择丙二醛(MDA)为脂类氧化指标,选择彗星实验(SCGE)和微核试验为DNA损伤指标。测定目标离子液体对生物体内抗氧化酶系和解毒酶系的影响、对DNA的损伤和活性氧簇(ROS)在生物体内形成和积累规律,综合评价咪唑类离子液体对生物的生态毒性,为离子液体的生态安全性评价及低生态毒性离子液体的设计提供依据。

离子液体由于其独特的理化性质,被认为是一种绿色溶剂. 然而近几年, 离子液体的毒性引起人们的注意. 本课题选取三种典型咪唑类离子液体1-辛基-3-甲基咪唑氯化盐 ([C8mim]Cl), 1-辛基-3-甲基咪唑溴化盐([C8mim]Br)和1-辛基-3-甲基咪唑六氟磷酸盐([C8mim]PF6) 为代表研究了离子液体对斑马鱼、赤子爱胜蚓和小麦三种典型生物的毒性影响。为离子液体的环境安全评价提供了依据。. 对斑马鱼的毒性研究表明, [C8mim]Cl, [C8mim]Br和[C8mim]PF6 对斑马鱼有毒性效应, 对本实验中所测定指标均有显著诱导或抑制效应。经3种离子液体暴露后，斑马鱼体内ROS含量随着离子液体浓度增加而显著升高。活性氧进而导致斑马鱼的DNA损伤和脂质过氧化，DNA损伤的程度随着离子液体浓度升高和暴露时间延长而显著增大。即使在低浓度(5mg/L), DNA损伤的程度比对照也出现显著性差异。在暴露期间,斑马鱼体内抗氧化酶(SOD,CAT)活性发生异常,表明3种离子液体可能已在斑马鱼细胞内造成氧化损伤。. 对蚯蚓的毒性研究结果表明,经3种离子液体暴露后，低浓度处理(5mg/L) ROS含量没有明显变化，而高浓度处理中ROS含量显著升高。同时,蚯蚓体内脂质过氧化程度也出现类似于ROS变化的趋势。在低浓度处理组(5mg/L) MDA含量几乎没有变化，而高浓度中MDA含量显著升高。然而，3种离子液体低浓度(5mg/L)却造成了蚯蚓体腔细胞内DNA的严重损伤。此外，3种离子液体还导致了蚯蚓细胞内抗氧化酶(SOD,CAT,POD)及解毒酶(GST)活性异常。. 对小麦的毒性研究结果表明, 3种离子液体对小麦幼苗的生长具有显著的抑制效应。经3种离子液体暴露后,小麦幼苗的发芽率、株高、根长、干重和色素含量被显著抑制,而且随着3种离子液体浓度的升高和暴露时间的延长,这种抑制作用逐渐加强。然而,小麦幼苗体内脯氨酸含量经暴露后显著升高。此外, 3种离子液体还导致小麦幼苗体内活性氧含量显著上升, 进而导致脂质过氧化和抗氧化酶(SOD,POD,CAT,APX)活性的异常,造成氧化损伤。