Synthesis and identifications of potential metabolites as biomarkers of the synthetic cannabinoid AKB-48

AKB-48 belongs to the family of synthetic cannabinoids. It has strong binding affinity to CB1 receptor and is psychoactive. It is banned in many countries including USA, Japan, Germany, New Zealand, Singapore and China etc. But the difficulty in detecting the parent compound in urine samples highlights the importance of studies of its metabolites. Here we report the synthesis of 19 potential metabolites of AKB-48, among which, compounds 2, 9, 10, 30 and 31, together with the commercially available substance 5 were identified as metabolites of AKB-48 by comparison with one authentic human urine sample and human liver microsomal data. Compounds 10 and 30 could be of use as biomarkers in detecting AKB-48 in human urine samples.