Detection, identification and quantification by 1H NMR of adulterants in 150 herbal dietary supplements marketed for improving sexual performance
Highlights
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- NMR analysis of one hundred and fifty 100% natural dietary supplements enhancing sexual performance.
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- 61% were adulterated with PDE-5 inhibitors, 5.5% with other drugs.
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- Up to four PDE-5 inhibitors were detected in the same formulation.
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- Manufacturers change the chemical composition of formulations over time.
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- Poor manufacturing practices were revealed in several cases.
Abstract
One
hundred and fifty dietary supplements (DS) marketed to increase sexual
performance were analyzed. All these formulations were claimed to
contain only natural compounds, plant extracts and/or vitamins. 1H
NMR spectroscopy was used for detecting the presence of adulterants and
for their identification and quantification. Mass spectrometry was used
as a complementary method for confirming the chemical structures. 61%
of DS were adulterated with phosphodiesterase-5 inhibitors (PDE-5i) (27%
with the PDE-5i medicines sildenafil, tadalafil and vardenafil, and 34%
with their structurally modified analogues). Among them, 64% contained
only one PDE-5i and 36% mixtures of two, three and even four. The
amounts of PDE-5i medicines were higher than the maximum recommended
dose in 25% of DS tainted with these drugs. Additional 5.5% DS included
other drugs for the treatment of sexual dysfunction (yohimbine,
flibanserin, phentolamine, dehydroepiandrosterone or testosterone). Some
DS (2.5%) contained products (osthole, icariin) extracted from plants
known to improve sexual performance. Only 31% of the samples could be
considered as true herbal/natural products. A follow-up over time of
several DS revealed that manufacturers make changes in the chemical
composition of the formulations. Lack of quality or consistent
manufacture (contamination possibly due to inadequate cleaning of the
manufacturing chain, presence of impurities or degradation products,
various compositions of a given DS with the same batch number,
inadequate labelling) indicated poor manufacturing practices. In
conclusion, this paper demonstrates the power of 1H NMR
spectroscopy as a first-line method for the detection of adulterated
herbal/natural DS and the need for more effective quality control of
purported herbal DS.
Graphical abstract
Abbreviations
- AminTad, aminotadalafil;
- DepipTSild, depiperazinothiosildenafil;
- DHEA, dehydroepiandrosterone;
- dMcarbo, desmethylcarbodenafil;
- DOSY NMR, diffusion-ordered spectroscopy NMR;
- DS, dietary supplements;
- dTdMcarbo, dithiodesmethylcarbodenafil;
- MSild, methisosildenafil;
- NorTad, nor-tadalafil;
- PDE-5i, phosphodiesterase-5 inhibitor;
- Phe, phentolamine;
- PP-Sild, propoxyphenyl-sildenafil;
- PP-THHSild, propoxyphenyl-thiohydroxyhomosildenafil;
- Sild, sildenafil;
- Tad, tadalafil;
- THSild, thiohomosildenafil;
- THHSild, thiohydroxyhomosildenafil;
- TMSild, thiomethisosildenafil;
- TSild, thiosildenafil;
- TSP, sodium 2,2,3,3-tetradeutero-3-(trimethylsilyl)propanoate;
- Vard, vardenafil;
- Yo, yohimbine
Keywords
- Dietary supplements;
- Adulteration;
- PDE-5 inhibitors;
- NMR;
- Mass spectrometry
- Corresponding author. Tel.:
+33 561556890.
Copyright © 2014 Elsevier B.V. All rights reserved.
