Separation and structural elucidation of a new tadalafil analogue diethylaminopretadalafil included as an adulterant in a dietary supplement.

A new tadalafil analogue was detected and isolated from a dietary supplement, the structure was elucidated by means of nuclear magnetic resonance (NMR) and mass spectroscopy. The compound was determined to be diethylaminopretadalafil, which might be derived from a precursor in the synthesis of tadalafil.