Di Shanshan, Liu Zhenzhen, Zhao Huiyu, Li Ying, Qi Peipei, Wang Zhiwei, Xu Hao, Jin Yuanxiang, Wang Xinquan
State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products/ Key Laboratory of Detection for Pesticide Residues and Control of Zhejiang, Institute of Agro-product Safety and Nutrition, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, PR China; Agricultural Ministry Key Laboratory for Pesticide Residue Detection, Hangzhou 310021, PR China.
College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310032, PR China.
Environ Int. 2022 Aug;166:107374. doi: 10.1016/j.envint.2022.107374. Epub 2022 Jun 27.
As a ubiquitous tire antidegradant, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) is persistently released into the environment. It is highly toxic to aquatic organisms, and its transformation product 6PPD-quinone (6PPD-Q), is "very highly toxic" to Oncorhynchus kisutch at a median lethal concentration (LC) of < 0.1 ng/mL. Notably, 6PPD and 6PPD-Q are chiral compounds. Here, enantioselective evaluations, including hydrolysis and acute toxicity were conducted after preparing the enantiomer, confirming the enantiomer absolute configuration and establishing enantioseparation methods. In the 6PPD hydrolysis experiments, the products 6PPD-Q, phenol, 4-[(1,3-dimethylbutyl)amino]- (4-DBAP) and 4-hydroxydiphenylamine (4-HDPA) were detected. In different water solutions, the hydrolysis of 4-DBAP and 4-HDPA was very fast (0.87-107 h), while the 6PPD-Q hydrolysis half-lives (12.8-16.3 d) were significantly longer than 6PPD (4.83-64.1 h). At the enantiomeric level, no enantioselective hydrolysis and conversion occurred. R-6PPD generated R-6PPD-Q, and S-6PPD generated S-6PPD-Q, and the formation rate of S-6PPD-Q was 1.77 times faster than R-6PPD-Q. In terms of the enantioselective toxicity, the 6PPD enantiomer was highly toxic to China-specific Gobiocypris rarus (LC, 162-201 ng/mL), and it had no enantioselective difference. 6PPD-Q was "very highly toxic" (LC, 1.66-4.31 ng/mL) to Oncorhynchus mykiss, which is of commercial importance, and the toxicities of rac-6PPD-Q and S-6PPD-Q were 1.9 and 2.6 times higher than R-6PPD-Q. Furthermore, the formation concentrations of S-6PPD-Q and R-6PPD-Q in 6PPD water solutions were higher than the LC values of O. kisutch and O. mykiss, and the toxicity of 6PPD-Q was highly species-specific, which should raise concern. These results provide important information for environmental risk assessments of 6PPD and 6PPD-Q, especially from the perspective of enantiomers.
作为一种普遍存在的轮胎抗降解剂，N-(1,3-二甲基丁基)-N'-苯基对苯二胺（6PPD）持续释放到环境中。它对水生生物具有高毒性，其转化产物6PPD-醌（6PPD-Q）对虹鳟鱼的半数致死浓度（LC）<0.1 ng/mL，“毒性极高”。值得注意的是，6PPD和6PPD-Q是手性化合物。在此，在制备对映体后进行了对映选择性评估，包括水解和急性毒性评估，确定了对映体的绝对构型并建立了对映体分离方法。在6PPD水解实验中，检测到了产物6PPD-Q、苯酚、4-[(1,3-二甲基丁基)氨基] -（4-DBAP）和4-羟基二苯胺（4-HDPA）。在不同水溶液中，4-DBAP和4-HDPA的水解非常快（0.87-107小时），而6PPD-Q的水解半衰期（12.8-16.3天）明显长于6PPD（4.83-64.1小时）。在对映体水平上，未发生对映选择性水解和转化。R-6PPD生成R-6PPD-Q，S-6PPD生成S-6PPD-Q，S-6PPD-Q的生成速率比R-6PPD-Q快1.77倍。就对映选择性毒性而言，6PPD对中国特有的稀有鮈鲫具有高毒性（LC，162-201 ng/mL），且无对映选择性差异。6PPD-Q对具有商业重要性的虹鳟鱼“毒性极高”（LC，1.66-4.31 ng/mL），外消旋6PPD-Q和S-6PPD-Q的毒性分别是R-6PPD-Q的1.9倍和2.6倍。此外，6PPD水溶液中S-6PPD-Q和R-6PPD-Q的生成浓度高于虹鳟鱼和虹鳟的LC值，且6PPD-Q的毒性具有高度物种特异性，这应引起关注。这些结果为6PPD和6PPD-Q的环境风险评估提供了重要信息，特别是从对映体的角度。
