Tentative identification of phase I metabolites of HU-210, a classical synthetic cannabinoid, by LC–MS/MS

(6aR,10aR)-9-(Hydroxymethyl)-6,6-dimethyl-3-(2-methyloctan-2-yl)-6a,7,10,10a-tetrahydrobenzo[c]chromen-1-ol (HU-210) is a synthetic cannabinoid, with a classical cannabinoid structure similar to Δ9-tetrahydrocannabinol (Δ9-THC). In this study, the in vitro metabolism of HU-210 was investigated in human liver microsomes to characterize associated phase I metabolites. HU-210 was incubated with human liver microsomes, and the reaction mixture was analyzed using LC–MS/MS. HU-210 was metabolized in human liver microsomes, yielding about 24 metabolites. These metabolites were structurally characterized on the basis of accurate mass analyses and MS/MS fragmentation patterns. The major metabolic route for HU-210 was oxygenation. Metabolites M1–M7 were identified as mono-oxygenated metabolites; M8–M15, mono-hydroxylated metabolites; M16–M20, di-oxygenated metabolites; and M21–M24, di-hydroxylated metabolites. These results provide evidence for in vivo HU-210 metabolism, and they may be applied to the analysis of HU-210 and its relevant metabolites in biological samples.