Comparative In Vitro and In Vivo Hydroxylation Metabolization of Polychlorinated Biphenyl 101 in Laying Hens: A Pilot Study

Abstract

Polychlorinated biphenyls (PCBs) can be metabolized into hydroxylated PCBs (OH-PCBs) that exhibit greater toxicity than their parent compounds. In particular, 2,2′,4,5,5′-pentachlorobiphenyl (PCB 101) is commonly found in chicken feeds and breeding environments, although information on the biotransformation of this PCB in chickens is lacking. In this study, the hydroxylation metabolization of PCB 101 was assessed based on in vitro trials with Sanhuang chicken liver microsomes and in vivo experiments with Hy-Line Brown hens. The para-substituted metabolite 4′-OH-PCB 101 is the predominant metabolite of PCB 101. 4′-OH-PCB 101 is preferentially retained in the chicken bloodstream and partly distributed into different tissues of laying hens. The blood−brain barrier can effectively prevent the OH-PCB from entering the brain, and the adipose tissue contains a relatively low residue concentration of the OH-PCB. The laying hen can deplete the OH-PCB via laying eggs and excrement. The ratio of 4′-OH-PCB 101/PCB 101 in egg yolk is about 1:2. These results first provide definite evidence for the previous hypothesis of the PCB 101 metabolism by chickens. They could assist in predicting the environmental fate of PCBs, and in the risk assessment of PCBs and OH-PCBs in chicken-based foodstuffs.

Development of an Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry Method for Hydroxylated Polychlorinated Biphenyls in Animal-Derived Food

“…The average recoveries were between 76.7% and 116.5%, while the RSD values ranged from 2.2% to 18.4%. As shown in Figure S6 , the values determined by this method were consistent with the ones confirmed using GC-MS/MS by the pH partitioning clean-up methods [ 14 ] with less than 15% relative deviations. Moreover, the present method has lower RSD values.…”

“…The limit of detection (LOD) and limit of quantification (LOQ) values were calculated as the average concentration of each compound produced a signal-to-noise ratio (S/N) of 3 and 10, respectively, based on the sample at the lowest spiked concentration level. Finally, the proposed method was further verified using real egg samples, which were produced by laying hens after dietary exposure to PCB 101 (5 μg/kg in feeds) [ 14 ].…”

“…In general, OH-PCBs are ready to be excreted via urine and bile in animals. However, some OH-PCBs can be stably retained in animal bodies and transferred from the maternal to the eggs, resulting in a secondary foodborne risk together with their precursor compounds [ 14 ]. Therefore, it is necessary to develop methods for the detection of OH-PCBs, especially the predominant congeners, in animal-derived food.…”