2-碘芴在鲮鱼(Cirrhina molitorella)中的积累、分布、代谢和排泄

Study on the Accumulation,Distribution,Metabolism and Excretion of 2-Iodofluorene in Mud Carp,Cirrhina molitorella

卤代芴是近年发现的新型环境污染物,目前尚无其生态毒理学研究的报道。以^(125)I-2-碘芴(^(125)I-2-IFlu)作为2-碘芴(2-IFlu)的放射性示踪剂,研究了2-IFlu在鲮鱼(Cirrhina molitorella)中的吸收、分布、代谢和排泄过程;同时,以2-溴芴(2-Br Flu)作为2-IFlu的质谱示踪剂,进一步对2-IFlu在鲮鱼体内的生物转化产物进行结构表征。结果表明,鲮鱼对2-IFlu的积累表现为波浪式增长,浓集系数在积累7 d时达到1 251.13。2-IFlu及其代谢产物主要积累在鲮鱼的胆囊部位,峰值时所占比例超过生物总吸收量的60%,此时胆囊的浓集系数达78.85×103。鲮鱼对2-IFlu的排泄具有清晰的快、慢两个排泄阶段,排泄实验开始后短时间内拥有较快排泄速度,残留率降至19.20%,之后转入慢速排泄。快排泄期2-IFlu及其代谢物仍主要分布于胆囊部位,慢排泄期时分布于其余内脏和剩余组织中。对胆汁的甲醇提取物进行薄层层析-放射自显影分析发现,积累4 d时鲮鱼胆汁中的2-IFlu全部以其代谢物形式存在,主代谢产物为3种大极性物质。经质谱确认,鲮鱼胆汁中的2-IFlu代谢主产物为2-IFlu-硫酸酯、2-IFlu-(OH)-硫酸酯、2-IFlu-葡萄糖醛酸和2-IFlu-(OH)-葡萄糖醛酸。表明2-IFlu进入鲮鱼体内后,很快被转化为一相代谢氧化产物,随之发生后续的二相代谢过程进一步转化为极性基团加合的代谢产物,最终排出体外。

Halogenated fluorene is a new type of environmental contaminants discovered recently. However,their ecotoxicological profiles remain largely unknown. In this study we used ^125I-2-Iodofluorene（^125I-2-IFlu） as a radioactive tracer to study the accumulation,distribution,metabolism and excretion of 2-Iodofluorene（ 2-IFlu） in mud carp（ Cirrhina molitorella）. In addition,2-Bromofluorene（ 2-Br Flu） was used as a mass spectrometry tracer to characterize the metabolites of 2-IFlu in the fish. The results showed that the accumulation of 2-IFlu in mud carp presented a fluctuant increase and did not reach plateau during the 7 days ＇exposure. The accumulation factor reached to 1 251. 13 by the 7thday. 2-IFlu was mainly distributed in the gall bladder,accounting for more than60% of the 2-IFlu values detected in the fish. The accumulation factor in gall bladder reached 78. 85 × 10^3. The excretion for 2-IFlu from the fish was clearly composed of a fast excretion phase and a slow excretion phase. At the end of the fast excretion phase,the retention rate of 2-IFlu in fish decreased to 19. 2%,and then the excretion switched to slow phase. During the fast excretion phase,2-IFlu was mainly in gall bladder whereas 2-IFlu was distributed in in other visceral tissues during the slow excretion phase. Mass spectrometric analyses of 2-Br Flu metabolites suggested that,2-IFlu was quickly transformed into three highly polar metabolites and no parent 2-IFlu could be detected in the gall bladder of mud carp after a 4 days＇ exposure. 2-IFlu-sulfate,2-IFlu-（ OH）-sulfate,2-IFluglucuronide and 2-IFlu-（ OH）-glucuronide were the dominant metabolites of 2-IFlu in the bile of mud carp. The results indicate that mud carp can rapidly transform 2-IFlu into its hydroxide after a process of phase-Ⅰ metabolism,and produce higher polar metabolites by phase-Ⅱ metabolism,and eventually excrete them from the body.