Elucidation of two new corticosteroids, betamethasone dibutyrate and betamethasone tributyrate

Corticosteroids were used normally as anti-inflammatory drugs. However, in some area certain corticosteroids might be illegally used as growth promoting agent in feed, and as prohibited doping substances in game and sport for human or/and animal performance-enhancing. Synthesized structural similar corticosteroids were popular in black market because they can pass routine drug screening. In this study two new artificial synthesized corticosteroids were found in claimed hydrolyzed wheat product. Liquid chromatography coupled with high resolution mass spectrometry (HRMS, Orbitrap) was applied to separate and elucidate the corticosteroids in the sample. Two unknown peaks with optical spectra similar to corticosteroids were first screened out at the beginning, and then their accurate molecular weight (M + H⁺) m/z 533.29059 and m/z 603.33289 were detected by HRMS. Element formulas of unknowns were calculated by the accurate mass and isotopes abundance. Structures were proposed by their fragment ions at high energy collision dissociation (HCD, 10 eV) and compared with candidate standard compounds. The two unknowns shared similar molecular skeleton with steroid core structure and presented man made fluorine element in their molecule. As the results, the unknowns in the sample were artificial synthesized, and the sample product was not a real food. The detected corticosteroids were also synthesized as reference compounds for conformation. Two new corticosteroids named betamethasone dibutyrate and betamethasone tributyrate were found and first time reported in this work. The legality of structural similar/modified corticosteroids were blurry and their safety were unverified. The confirmed identifications of two new found corticosteroids, and their mass spectra were provided in this paper for the reference of drug detection.