Isolation and structural characterization of a new tadalafil analog (chloropropanoylpretadalafil) found in a dietary supplement

A screen for known PDE-5 inhibitors in a dietary supplement product marketed for “enhanced sexual performance” detected a compound that structurally resembled chloropretadalafil, a known analog of tadalafil. The compound was isolated from the supplement matrix using high performance liquid chromatography with ultraviolet detection (HPLC-UV) and a fraction collector, and was further characterized using gas chromatography with Fourier Transform infrared detection and mass spectral detection (GC/FT-IR/MS), as well as high resolution mass spectrometry (HRMS). The analog had an accurate mass of m/z 441.1216 (error is 0.8706 ppm) for the protonated species [M+H]+, corresponding to a molecular formula of C23H22ClN2O5. HRAM and GC/FT-IR/MS mass spectral fragmentation data suggested that the modification is a chloropropanoyl moiety extending from the nitrogen on the piperidine ring of chloropretadalafil. The proposed new analog has been named chloropropanoylpretadalafil.