3-Ethenylpyridine (3-EP) is a major nicotine pyrolysis product present in the gas phase of tobacco smoke. For a number of years it has been used as an environmental tracer for tobacco smoke. It would be expected to be a useful tobacco smoke biomarker as well, but nothing has been published about its metabolism and excretion. As part of our studies to develop 3-EP as a biomarker, we developed analytical methods for likely metabolites. One likely metabolite, 3-pyridylethylene glycol (3-EP Diol) was detected in smokers’ urine and in rat liver homogenates incubated with 3-EP. In addition to being a candidate biomarker, the likely metabolic pathway for its formation would involve the intermediacy of 3-(2-oxiranyl)-pyridine (3-EP Epoxide), followed by conversion to the diol catalyzed by epoxide hydrolase. This may have toxicological significance. Epoxides formed metabolically from alkenes can be carcinogenic or cytotoxic. Butadiene, a human carcinogen, is metabolically activated to epoxides thought to be responsible for its carcinogenicity. Styrene is metabolically activated to an epoxide, styrene-7,8-oxide. Both styrene and its epoxide are considered probable human carcinogens by the International Agency for Research on Cancer (IARC). 3-EP is structurally similar to styrene suggesting possible toxicity. In this presentation we will describe our studies to develop 3-EP as a biomarker and discuss evidence for metabolic formation of 3-EP epoxide.

1-(3-Pyridinyl)-1,2-dihydroxyethane (3-pyridylethylene glycol) is excreted in smokers’ urine. Evidence for metabolic epoxidation of 3-ethenylpyridine from inhaled tobacco smoke

ACS Fall 2020 Virtual Meeting

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