Epigallocatechin gallate

Epigallocatechin gallate (EGCG), a diester of epigallocatechin and gallic acid, is a polyphenol dietary supplement that is purported to have benefits to human immune function. (Catechins such as EGCG belong to the class of compounds known as flavonoids.) Naturally occurring EGCG is most commonly found in tea leaves, especially in green tea.

p-Synephrine, or simply synephrine, is a dietary supplement that was originally extracted from various orange species. It exists as two optical isomers; the one shown here is the more common (R)- (or D-) enantiomer. It is a positional isomer of m-synephrine, also called neosynephrine or phenylephrine. Both molecules are decongestants and vasodilators.

ECGC and p-synephrine are two of many substances found in sports nutrition products. But evidence for the efficacy of these products is hard to come by. Most clinical studies on sports supplements have 12 or fewer participants, so the data obtained must be very strong to be statistically significant.

Another downside of sports nutrition products is that they may pose health dangers. For example, ephedra, with a structure similar to that of p-synephrine, was banned by the US Food and Drug Administration because it raises blood pressure.