Fullove Tracie Perkins, Yu Hongtao
Toxicol Res (Camb). 2013 May 1;2(3):193-199. doi: 10.1039/C3TX20085J.
Polycyclic aromatic hydrocarbons (PAHs), a class of mutagenic environmental contaminants, insert toxicity through both metabolic activation and light irradiation. Pyrene, one of the most widely studied PAHs, along with its mono-substituted derivatives, 1-amino, 1-bromo, 1-hydroxy, and 1-nitropyrene, were chosen to study the effect of substituents on their phototoxicity, DNA damage and repair. Both alkaline Comet assay, which detects direct DNA damages, and endonuclease Comet assay, which detects oxidative DNA damages, were conducted at 0, 2, 4, 8, and 24 h of incubation of the cells in minimal growth medium after concomitant exposure to pyrene derivatives and UVA light. All these compounds are photocytotoxic and the phototoxicity is both incubation time and PAH dose dependent; whereas, those without light are not toxic. The LC obtained are in the range of 3.5 - 9.3 µM. Cellular DNA damages, both direct and oxidative, are observed immediately after the cells are treated with UVA light and the pyrene derivatives at a concentration of 1.0 µM. The amount of DNA damages (both direct and oxidative) increase from 0 to 4 h of incubation. After 4 hours, subsequent damage induction declines, and this is perceived to be mainly through DNA repair. After longer incubation of 8 h, the damaged cellular DNA start to be repaired, resulting in greatly reduced amount of DNA damages, and the DNA damage reaches the minimum at 24 h of incubation. 1-Amopyrene and 1-hydroxypyrene cause more DNA oxidative damages immediately after the exposure (0 h of incubation), and these damages are repaired within the same timeframe as the other tested compounds. The oxidative DNA damages caused by 1-bromopyrene are repaired starting at 2 h of incubation, earlier than the damages caused by all the other compounds.
多环芳烃（PAHs）是一类具有致突变性的环境污染物，可通过代谢活化和光照两种方式产生毒性。芘是研究最为广泛的多环芳烃之一，连同其单取代衍生物1-氨基芘、1-溴芘、1-羟基芘和1-硝基芘一起，被用于研究取代基对其光毒性、DNA损伤及修复的影响。在细胞于基本生长培养基中与芘衍生物及紫外线A（UVA）光同时暴露后，分别于孵育0、2、4、8和24小时进行碱性彗星试验（检测直接DNA损伤）和核酸内切酶彗星试验（检测氧化性DNA损伤）。所有这些化合物都具有光细胞毒性，且光毒性既取决于孵育时间，也取决于多环芳烃剂量；而无光照时则无毒。所测得的半数致死浓度（LC）在3.5至9.3微摩尔范围内。在用浓度为1.0微摩尔的UVA光和芘衍生物处理细胞后，可立即观察到细胞的直接和氧化性DNA损伤。DNA损伤量（直接损伤和氧化性损伤）在孵育0至4小时内增加。4小时后，后续损伤诱导作用下降，这被认为主要是通过DNA修复。在孵育8小时更长时间后，受损的细胞DNA开始修复，导致DNA损伤量大幅减少，且在孵育24小时时DNA损伤达到最小值。1-氨基芘和1-羟基芘在暴露后（孵育0小时）立即造成更多的DNA氧化性损伤，且这些损伤在与其他受试化合物相同的时间范围内得到修复。1-溴芘造成的氧化性DNA损伤从孵育2小时开始修复，比其他所有化合物造成的损伤修复时间更早。
