In vitro metabolism of 17beta-Boldenone and Boldione

The in vitro biotransformation of 17beta-Boldenone (BOLD) and of Boldione (ADD) was studied using hepatic S9 fractions and microsomes obtained from livers of control veal calves. Metabolites were eluted by liquid chromatography (HPLC) with gradient elution and their identity confirmed by mass spectrometry (LCMS). When BOLD was incubated with microsomes or S9 fraction and a NADPH generating system, two main hydroxyl metabolites further to ADD were detected. When ADD was added to incubation assays, BOLD and only one hydroxyl metabolite were found as main metabolites, further to small amounts of several polar and non polar unidentified ones. Although alfa-boldenone in the conjugated form is the major metabolite detected in urine when BOLD and ADD are administered in vivo, no alfa-boldenone was detected in vitro. As urinary hydroxyl derivatives can be of help confirming illicit treatment, the presence of hydroxyl derivatives would be in checked in urine sample from in vivo BOLD treated animals, while the in vitro production of metabolites including the alpha epimer would be studied with ADD and BOLD incubated with liver subcellular fractions obtained from BOLD treated calves or from other different calf tissues