Identification of Cytochrome P450 Enzymes Responsible for Oxidative Metabolism of Synthetic Cannabinoid (1-Hexyl-1H-Indol-3-yl)-1-naphthalenyl-methanone (JWH-019)

(1-Hexyl-1H-indol-3-yl)-1-naphthalenyl-methanone (JWH-019) is one of the second-generation synthetic cannabinoids which as a group have been associated with severe adverse reactions in humans. Although metabolic activation can be involved in the mechanism of action, the metabolic pathway of JWH-019 has not been fully investigated. In the present study, we aimed to identify the enzymes involved in the metabolism of JWH-019. JWH-019 was incubated with human liver microsomes (HLMs) and recombinant cytochrome P450s (P450s or CYPs). An animal study was also conducted to determine the contribution of the metabolic reaction to the onset of action. Using an ultra-performance liquid chromatography system connected to a single-quadrupole mass detector, we identified 6-OH JWH-019 as the main oxidative metabolite in HLMs supplemented with NADPH. JWH-019 was extensively metabolized to 6-OH JWH-019 in HLMs with the K-M and V-max values of 31.5 & mu;M and 432.0 pmol/min/mg. The relative activity factor method estimated that CYP1A2 is the primary contributor to the metabolic reaction in the human liver. The animal study revealed that JWH-019 had a slower onset of action compared to natural and other synthetic cannabinoids. CYP1A2 mediates the metabolic activation of JWH-019, contributing to the slower onset of its pharmacological action.