School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.
Chemosphere. 2010 Apr;79(4):355-61. doi: 10.1016/j.chemosphere.2010.02.024. Epub 2010 Mar 3.
In the present study, two Microsystins (MCs) of Microcystin-LR and Microcystin-RR were degraded with different dosages of ozone (O(3)). The possible degradation pathways were elucidated by analyzing their intermediates and end-products with liquid chromatography-mass spectrometry (LC-MS) method. The toxicity of the MCs ozonation products was also evaluated by assaying the protein phosphatase inhibition in vitro and acute toxicity in vivo. Results demonstrated that ozonation was a promising technology for removal and detoxification of the cyanotoxins. The MCs destruction was mainly involved in the attack of ozone on Adda side chain. First, the conjugated diene structure of Adda moiety was attacked by hydroxyl radical (OH()) to produce dihydroxylated products, then the hydroxylated 4-5 and/or 6-7 bond of Adda was cleaved into aldehyde or ketone peptide residues, and finally the residues were oxidized into the corresponding carboxylic acids. The fragmentation of the Mdha-Ala peptide bond of MCs also contributed positively to the oxidation process. Additionally, the attack on the benzene ring of Adda side chain was exclusively observed during MC-RR degradation. The toxicity evaluation of MCs ozonation products revealed that those end-products had no adverse effects in vivo and in vitro ozonation that could completely remove the MCs' toxicity.
在本研究中，采用不同剂量的臭氧（O(3)）对两种微囊藻毒素（MCs）——微囊藻毒素-LR 和微囊藻毒素-RR 进行了降解。通过液相色谱-质谱（LC-MS）法分析其中间产物和最终产物，阐明了可能的降解途径。还通过体外测定蛋白磷酸酶抑制作用和体内急性毒性评估了 MCs 臭氧化产物的毒性。结果表明，臭氧化是一种有前途的去除和解毒蓝藻毒素的技术。MCs 的破坏主要涉及臭氧对 Adda 侧链的攻击。首先，Adda 部分的共轭二烯结构被羟基自由基（OH()）攻击，生成二羟基产物，然后 Adda 的羟基化 4-5 和/或 6-7 键被裂解成醛或酮肽残基，最后残基被氧化成相应的羧酸。MCs 的 Mdha-Ala 肽键的断裂也对氧化过程有积极贡献。此外，在 MC-RR 降解过程中仅观察到对 Adda 侧链苯环的攻击。MCs 臭氧化产物的毒性评估表明，这些终产物在体内和体外臭氧化过程中没有不良影响，完全去除了 MCs 的毒性。
