Detection and quantification of phenethylamines in sports dietary supplements by NMR approach

Authors: ZHAO, JIANPING - University Of Mississippi; WANG, MEI - University Of Mississippi; AVULA, BHARATHI - University Of Mississippi; KHAN, IKHLAS - University Of Mississippi

Submitted to: Journal of Pharmaceutical and Biomedical Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2018
Publication Date: 1/31/2018
Citation: Zhao, J., Wang, M., Avula, B., Khan, I.A. 2018. Detection and quantification of phenethylamines in sports dietary supplements by NMR approach. Journal of Pharmaceutical and Biomedical Analysis. 151:347-355. https://doi.org/10.1016/j.jpba.2018.01.025.
DOI: https://doi.org/10.1016/j.jpba.2018.01.025

Interpretive Summary: Phenethylamines (PEAs) have been also found in the plants of other families, including species in the genera of Acacia, Ephedra, Hordeum, Desmodium, Sida, Prunus, and Citrus, and some of these plant materials have been used as the ingredients of dietary supplements. Additionally, a number of synthesized PEA chemicals, including those previously marked as pharmaceutical drugs or those newly emerged without safety profiles, have also been found in many dietary supplements and pose a significant risk to consumers’ health. In the present study, thirty-two sports dietary supplements collected from the market were studied by using NMR as a tool for the identification and quantification of PEAs in formulation of the products. The labeled and un-labeled PEAs in the supplement products were detected and identified by the analyses of 1D and 2D NMR spectra without chromatographic pre-separations. In addition, a quantitative NMR method was developed and validated to simultaneously determine the contents of PEAs in the investigated supplement products. It was found that in many cases, the unlabeled PEAs were detected in the supplement products, while the PEAs listed on the label were actually not found. The study also found that the concentrations of PEAs (including the total and individual PEAs) varied tremendously in the different supplement products.

Technical Abstract: Phenethylamines (PEAs) are popular substances found in weight-loss and sports nutrition supplements. They are generally pharmacologically active and primarily affect the sympathetic nervous system. Many PEAs are synthetic chemicals and are on the prohibited list of the World Anti-Doping Agency. In this study, nuclear magnetic resonance (NMR) spectroscopy was applied to detect and identify the presence of PEAs in sports dietary supplements without the need for chromatographic separation or pre-knowledge on formulation. Eight PEAs, viz. phenethylamine, synephrine, oxilofrine, hordenine, ß-methylphenethylamine, N-methyltyramine, octopamine and deterenol, were identified from 32 dietary supplements sold in the US market. Furthermore, a quantitative NMR method was developed and validated for simultaneous determination of the concentrations of the PEAs. The study demonstrated that NMR could be a potential tool to monitor and detect PEAs or other ingredients in dietary supplements.