摘要:
多溴联苯醚(PBDEs)是应用广泛的溴代阻燃剂，其中2,2',4,4'-四溴联苯醚(BDE-47)和2,2',3,3',4,4',5,5',6,6'-十溴联苯醚(BDE-209)广泛存在于环境中。PBDEs具有神经毒性，但其致毒机制尚不明确。本文通过研究BDE-47与BDE-209对乙酰胆碱酯酶(AChE)活性的影响及二者与AChE相互作用的光谱分析，揭示BDE-47与BDE-209导致神经毒性的致毒机制。BDE-47和BDE-209在一定浓度范围内均能够抑制AChE分解乙酰胆碱；随着浓度的增加，两者的抑制率均呈现出先增加后降低的规律。BDE-47浓度为400 μmol·L-1时抑制率达到最大，为22.3%；BDE-209浓度为200 μmol·L-1时抑制率达到最大，为11.2%。相同浓度下，BDE-47对AChE的抑制率始终大于BDE-209，表明AChE对BDE-47更加敏感。荧光光谱分析结果表明BDE-47和BDE-209与AChE之间的相互作用均主要为疏水作用，同时不存在范德华引力作用；BDE-47与AChE的结合常数大于BDE-209与AChE的结合常数，表明BDE-47更易与AChE相互作用。此外，温度的升高不利于BDE-47和BDE-209与AChE之间相互作用。BDE-47和BDE-209抑制AChE活性很可能是导致神经毒性通路之一。
Abstract:
Polybrominated diphenyl ethers (PBDEs) are widely used as brominated flame retardants, among which both 2,2',4,4'-tetrabromodiphenylether (BDE-47) and 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether (BDE-209) are often detected in the environment. As known, PBDEs is of concern for the neurotoxicity. However, the neuro-toxicological mechanism is not clear yet. The effects of BDE-47 and BDE-209 on the activity of acetylcholinesterase (AChE) and the interaction between BDE-47, BDE-209 and AChE were investigated. The potential neuro-toxicological mechanism of BDE-47 and BDE-209 was also revealed. The results showed that BDE-47 and BDE-209 could inhibit AChE decomposition of acetylcholine in a certain concentrations range. With the increase of concentrations, the inhibition rates of BDE-47 and BDE-209 increased at first and decreased subsequently, and the maximum inhibition rate were 22.3% and 11.2%, respectively, at the concentration of BDE-47 of 400 μmol·L-1 and of BDE-209 of 200 μmol·L-1. At the same concentration, the inhibition of BDE-47 to AChE was always stronger than that of BDE-209, indicating that AChE was more sensitive to BDE-47. The results of fluorescence spectroscopy showed that the interaction between BDE-47 and BDE-209 and AChE was dominated by hydrophobic force. The binding constant of BDE-47 with AChE was greater than that of BDE-209 with AChE, suggesting that BDE-47 is more likely to interact with AChE. In addition, the increase of temperature restrains the interaction of BDE-47 and BDE-209 with AChE. The inhibition of BDE-47 and BDE-209 to AChE activity is likely to be one of the neurotoxic pathways.
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