Analytical Identification of Novel Furan Metabolites in Human Hepatocytes and Urine: Implications for Liver and Respiratory Disease Research

-pyrrol-3-yl)cysteine sulfoxide (NAC-BDA-ethanolamine sulfoxide) was detected in human urine. A sensitive LC-MS/MS assay for this metabolite was developed and applied to urine samples from a variety of smoke-exposed individuals as well as nonsmokers. Its levels were 2.5-5 times higher in people who smoke than in nonsmokers. They were not elevated in exclusive e-cigarette or cannabis users. Two case-control studies were performed to determine whether NAC-BDA-lysine metabolites or NAC-BDA-ethanolamine sulfoxide were associated with smoking-related diseases. In the first study, there was no association between any of the furan metabolites and liver cancer. In the second study, there was a suggestive association between NAC-BDA-ethanolamine sulfoxide and the risk of smoking-related respiratory disease symptoms. However, the overall trend was not significant. Therefore, there was no clear link between this furan metabolite and the risk of smoking-related respiratory disease symptoms.