Isolation and Characterization of New Tadalafil Analogues in Male Sexual Herbal Supplements

ABSTRACT New tadalafil analogues were found to be added illegally to an herbal supplement marketed for the enhancement of sexual function. The compounds were separated using flash column chromatography. The structures of the detected tadalafil analogues were elucidated by HPLC‐DAD/MS and nuclear magnetic resonance (NMR) spectroscopy. A protonated molecule at m/z 450.16 was detected by LC–MS, corresponding to a molecular formula of C 24 H 23 N 3 O 6 for both of the diastereomeric compounds. These unknown compounds ( 1 and 2 ) were identified as tadalafil analogues containing an additional dihydroxyethyl group and were named N ‐(2,3‐dihydroxypropyl)nortadalafil.