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

•In the present study, a new tadalafil analogue as an adulterant in a dietary supplement was detected and isolated.•The structure of the new analogue was elucidated by means of NMR, HPLC and mass spectroscopy.•The possible origination of the new analogue was also proposed here.•The structure of this analogue was identified and reported for the first time.

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.

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