2-Methyl-4'-(methylthio)-2-morpholinopropiophenone: A commercial photoinitiator being used as a new psychoactive substance

Abstract

Synthetic cathinones, which are novel psychoactive substances, have caused major social problems worldwide. A substance called 2-methyl-4′-(methylthio)-2-morpholinopropiophenone (MMMP), which is employed as a commercial industrial photoinitiator for triggering polymerization, has a basic cathinone backbone; however, few reports regarding MMMP have been published. In the current study, three potential metabolites of MMMP—namely hydroxy-MMMP (HO-MMMP), HO-MMMP-sulfoxide (HO-MMMP-SO), and HO-MMMP-sulfone (HO-MMMP-SO2)—were successfully synthesized, and MMMP and these three potential metabolites were used as standards to establish an analytic method based on liquid chromatography–tandem mass spectrometry for the quantitative analysis of urine. This analytic method and related parameters—including dynamic range, limit of quantification, selectivity, precision, accuracy, carryover effect, matrix effect, interference, and dilution integrity—were optimized and validated. Forty urine samples from 1,691 individuals who abused drugs were determined to contain MMMP, HO-MMMP, HO-MMMP-SO, or HO-MMMP-SO2; the results of this study indicate that approximately 2.37 % of drug abusers in Taiwan consumed MMMP in 2023. These 40 urine samples were analyzed to investigate the metabolism of MMMP in humans. The results indicate that HO-MMMP-SO is the main metabolite in human urine. This study recommends HO-MMMP-SO with a concentration of 2 ng/mL as a target and cutoff value, respectively, for identifying individuals who have consumed MMMP.