Structural characterization of dimethyldithiodenafil and dimethylthiocarbodenafil, analogs of sildenafil

•Dimethyldithiodenafil and dimethylthiocarbodenafil were detected in three powder products.•Dimethyldithiodenafil and dimethylthiocarbodenafil were established using HRMS and NMR.•Dimethyldithiodenafil was subjected to an X-ray structural analysis and PDE assay.•Three powder products contained 12–19mg dimethyldithiodenafil per tube.•Three powder products contained 1.4–3.9mg dimethylthiocarbodenafil per tube. Two analogs of sildenafil (compounds 1 and 2) were detected in three powder products acquired from online drug markets during an LC–UV–MS analysis of psychotropic drugs. Their structures were established by high-resolution mass spectrometry and NMR spectroscopy. Compound 1 was identified as 5-(5-(3,5-dimethylpiperazine-1-carbonothioyl)-2-ethoxyphenyl)-1-methyl-3-propyl-1H-pyrazolo[4,3-d]pyrimidine-7(6H)-thione and named dimethyldithiodenafil. Compound 2 was identified as 5-(5-(3,5-dimethylpiperazine-1-carbonothioyl)-2-ethoxyphenyl)-1-methyl-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-7(6H)-one and named dimethylthiocarbodenafil. Compound 1 was subjected to the phosphodiesterase assay (IC50=0.20nM). The three powder products were found to contain 12–19mg of dimethyldithiodenafil and 1.4–3.9mg of dimethylthiocarbodenafil per tube.