Isolation and structural elucidation of a new tadalafil analogue in health supplements: bisprenortadalafil

ABSTRACT

A new tadalafil analogue was found, along with nortadalafil, using HPLC-DAD during the inspection of a health product sold without official approval. The analogue was separated using a semi-preparative HPLC system and its structure was determined by a combination of mass spectrometry and NMR spectroscopy. The compound was identified as a tadalafil analogue in which the N-methyl group of tadalafil was replaced with a tadalafil precursor moiety. Nuclear Overhauser effect spectroscopy experiments suggested a cis-relationship between the substituents on a piperidine ring in the tadalafil moiety.

Graphical Abstract

KEYWORDS:

• Tadalafil analogue
• nortadalafil
• bisprenortadalafil
• PDE-5 inhibitor
• dietary supplement

Acknowledgements

Ji Hyun Lee and Han Na Park contributed equally to this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This research was supported by research grants [numbers 13181MFDS521 and 15182MFDS523] from the Ministry of Food and Drug Safety (MFDS), Korea, and by a 2015 research grant from Kangwon National University. The authors thank the Central Laboratory of Kangwon National University for providing them with technical assistance for the spectroscopic experiments.