Synthesis and in vitro Activity of Heterocyclic Inhibitors of CYP2A6 and CYP2A13, Two Cytochrome P450 Enzymes Present in the Respiratory Tract

To be sniffed at: Several 1- and 2-substituted 1H-imidazoles and 2-substituted oxazoles, oxazolines and pyrazines have been synthesized and tested as inhibitors of the cytochrome P450 enzymes CYP2A6 and CYP2A13. 1-Substituted 1H-imidazoles bearing short chains (pentyl, hexyl or hexenyl) were found to be potent inhibitors of both enzymes, and showed IC₅₀ values of about 2 μM.The synthesis of several heterocyclic compounds (1- or 2-substituted 1H-imidazoles and 2-substituted oxazoles, oxazolines and pyrazines) has been achieved. These compounds were tested as inhibitors of CYP2A6 and CYP2A13--two cytochrome P450 enzymes present in the respiratory tract--with a view to preventing the formation of carcinogenic metabolites of nicotine and inhibiting the metabolism of fragrances. 1-Substituted imidazoles bearing short alkyl chains displayed IC₅₀ values of around 2 μM for both enzymes, together with high vapour pressures.