Environmental contamination and human consumption of chickens could result in potential exposure to Roxarsone (3-nitro-4-hydroxyphenylarsonic acid), an organic arsenical that has been used as a chicken feed additive in many countries. However, little is known about the metabolism of Roxarsone in humans. The objective of this research was to investigate the metabolism of Roxarsone in human liver cells and to identify new arsenic metabolites of toxicological significance. Human primary hepatocytes and hepatocellular carcinoma HepG2 cells were treated with 20 or 100 µM Roxarsone. Arsenic species were characterized using a strategy of complementary chromatography and mass spectrometry. Results showed that Roxarsone was metabolized to more than 10 arsenic species in human hepatic cells. A new metabolite was identified as a thiolated Roxarsone. The 24-h IC50 values of thiolated Roxarsone for A549 lung cancer cells and T24 bladder cancer cells were 380 ± 80 µM and 42 ± 10 µM, respectively, which was more toxic than Roxarsone whose 24-h IC50 of A549 and T24 were 9300 ± 1600 µM and 6800 ± 740 µM, respectively. The identification and toxicological studies of the new arsenic metabolite are useful for understanding the fate of arsenic species and assessing the potential impact of human exposure to Roxarsone.
Environmental science & technology. 2017 Dec 27 [Epub ahead of print]
Qingqing Liu, Elaine M Leslie, Birget Moe, Hongquan Zhang, Donna N Douglas, Norman M Kneteman, X Chris Le