Abstract：
The detection of a putative 18-methyl-19-nortestosterone metabolite in a forensic bodybuilder\'s urine sample collected as part of a criminal proceeding has triggered a follow-up investigation. Four different dietary supplements in the possession of the suspect were examined with regard to possible precursor steroids. This led to the detection of the declared ingredient methoxydienone, which was confirmed by both, GC-MSMS and LC-HRMSMS. As neither 18-methyl-testosterone, nor 18-methyl-19-nortestosterone were detectable in the supplements, the possibility that the metabolite originates from methoxydienone was investigated. For this purpose, the metabolic fate of methoxydienone was studied in vitro using human HepG2 cells and in vivo by a single oral administration. While the 18-methyl-19-nortestosterone metabolite was not generated by HepG2 cells incubated with methoxydienone, it was observed in the urine samples collected at 2, 6, 10 and 24 h after methoxydienone administration. Moreover, the potential binding of methoxydienone as ligand to the human androgen receptor was modelled in silico in comparison with 18-methylnandrolone, for which androgen receptor activation had been shown in an in vitro approach before. In conclusion, we could ascribe the presence of the 18-methyl-19-nortestosterone metabolite in a forensic urine sample to originate from methoxydienone present in dietary supplements. Methoxydienone was observed to slowly degrade by demethylation of the methoxy substituent in liquid solutions. While no compound-specific intermediates were identified that allowed differentiation from other 18-methyl steroids, the 18-methyl-19-nortestosterone metabolite proved to be a suitable marker for reliable detection in doping analysis.
摘要：
在作为刑事诉讼的一部分收集的法医健美运动员的尿液样本中检测到推定的18-甲基-19-去甲睾酮代谢物引发了后续调查。就可能的前体类固醇检查了嫌疑人拥有的四种不同的膳食补充剂。这导致检测到申报的成分甲氧基二烯酮，两者都证实了这一点，GC-MSMS和LC-HRMSMS。因为没有18-甲基睾酮，补充剂中也没有检测到18-甲基-19-去甲睾酮，研究了代谢物源自甲氧基二烯酮的可能性。为此,使用人HepG2细胞在体外和通过单次口服给药在体内研究了甲氧基二烯酮的代谢命运。虽然18-甲基-19-去甲睾酮代谢物不是由与甲氧基二烯酮孵育的HepG2细胞产生的，在给予甲氧基二烯酮后2、6、10和24小时收集的尿液样品中观察到。此外，与18-甲基nandrolone相比，在计算机上模拟了作为配体的甲氧基二烯酮与人类雄激素受体的潜在结合，之前已经在体外方法中显示了雄激素受体激活。总之,我们可以将法医尿液样本中18-甲基-19-去甲睾酮代谢物的存在归因于膳食补充剂中存在的甲氧基二烯酮.观察到甲氧基二烯酮在液体溶液中通过甲氧基取代基去甲基化而缓慢降解。虽然没有化合物特异性中间体被鉴定出可以与其他18-甲基类固醇区分，18-甲基-19-去甲睾酮代谢物被证明是掺杂分析中可靠检测的合适标记物.
