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Oxidative Medicine and Cellular Longevity
Volume 2011 (2011), Article ID 482973, 9 pages
Review Article

A Review of the Receptor-Binding Properties of p-Synephrine as Related to Its Pharmacological Effects

1School of Pharmacy and Health Professions, Creighton University Medical Center, Omaha, NE 68178, USA
2Department of Medicine and Pathology, Georgetown University Medical Center, Washington, DC 22039, USA
3Faculty of Pharmacy, Jordan University of Science and Technology, Irbid 22110, Jordan

Received 18 January 2011; Accepted 7 June 2011

Academic Editor: Neelam Khaper

Copyright © 2011 Sidney J. Stohs et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Bitter orange (Citrus aurantium) extract and its primary protoalkaloid p-synephrine are used widely in weight loss/weight management and sports performance products. Because of structural similarities, the pharmacological effects of p-synephrine are widely assumed to be similar to those of ephedrine, m-synephrine (phenylephrine), and endogenous amine neurotransmitters as norepinephrine and epinephrine. However, small structural changes result in the receptor binding characteristics of these amines that are markedly different, providing a plausible explanation for the paucity of adverse effects associated with the wide-spread consumption of p-synephrine in the form of dietary supplements as well as in various Citrus foods and juices. This paper summarizes the adrenoreceptor binding characteristics of p-synephrine relative to m-synephrine, norepinephrine, and other amines as related to the observed pharmacological effects.