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Updated: May 29, 2026

Gramicidin-based Fluorescence Assay; for Determining Small Molecules Potential for Modifying Lipid Bilayer Properties
Published on: October 13, 2010
Effects of green tea catechins on gramicidin channel function and inferred changes in bilayer properties
Helgi I Ingólfsson1, Roger E Koeppe, Olaf S Andersen
1Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10065, United States. hei2001@med.cornell.edu
Abstract:
Green tea's health benefits have been attributed to its major polyphenols, the catechins: (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC), and epicatechin (EC). Catechins (especially EGCG) modulate a wide range of biologically important molecules, including many membrane proteins. Yet, little is known about their mechanism(s) of action. We tested the catechins' bilayer-modifying potency using gramicidin A (gA) channels as molecular force probes. All the catechins alter gA channel function and modify bilayer properties, with a 500-fold range in potency (EGCG>ECG≫EGC>EC). Additionally, the gallate group causes current block, as evident by brief downward current transitions (flickers).
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