Effects of External Factors on the Interaction of Tea Catechins with Lipid Bilayers

Abstract

Green tea contains a high concentration of such catechins as (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg). Their biological activities have been evaluated by in vitro experiments using cultured cells or bacteria, but the order of activity of the various catechins differed with the study. We have been studying the interaction of tea catechins with lipid bilayers, and clarified that the number of hydroxyl groups on the B-ring, the presence of the galloyl moiety, and the stereochemical structure of each catechin govern their affinity for lipid bilayers. We investigated in this present study the effects of various external factors on the affinity of tea catechins for lipid bilayers by using liposomes as model membranes. The amount of tea catechins incorporated into the lipid bilayers increased with increasing salt concentration in an aqueous medium and decreased with increasing negative electric charge of the lipid bilayers. Furthermore, the amount of EGCg or ECg incorporated into the lipid bilayers increased with increasing EC concentration. These results reveal that the salt concentration in an aqueous medium, the electric charge of the membrane, and the presence of other catechins governed the affinity of tea catechins for the lipid bilayers.

Direct Evidence of Interaction of a Green Tea Polyphenol, Epigallocatechin Gallate, with Lipid Bilayers by Solid-state Nuclear Magnetic Resonance

“…15,16) Furthermore, the salt concentration in an aqueous medium, the electric charges of the membrane, and the presence of other catechins were also important factors in the affinity of tea catechins for lipid bilayers. 17) These experimental findings suggested that interaction of catechins with the phospholipid domain of membranes occurs. But interaction of catechins with membranes has not been observed directly, and the site and the orientation of catechins in membranes of phospholipids have remained undiscovered.…”

“…We developed a method of estimating the affinity of polyphenols for cell membranes. 14) We examined the interaction of four catechins, i.e., epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate (EGCg: 1), with lipid bilayers, [15][16][17] and found that the order of the amount of tea catechins incorporated into liposomes was the same as that of the partition coefficients in a 1-octanol/phosphate-buffered saline system. We found that the affinity of tea catechins for lipid bilayers is governed by the number of hydroxyl groups on the Bring, the presence of the galloyl moiety, and the stereochemical structure of each catechin.…”

Solid‐state NMR analysis of the orientation and dynamics of epigallocatechin gallate, a green tea polyphenol, incorporated into lipid bilayers

“…[8] The salt concentration in an aqueous medium, the electric charges on the membrane, and the presence of other catechins, are also important factors affecting the affinity of tea catechins for lipid bilayers. [9] These experimental findings suggest that tea catechins interact with the phospholipid domains of membranes. To help elucidate their molecular mobility in the cell, we examined the interaction of tea catechins with lipid membranes using solid-state NMR techniques.…”

Quercetin and epigallocatechin gallate effects on the cell membranes biophysical properties correlate with their antioxidant potential

“…Several studies investigated the interaction between the two polyphenols and the cell membrane using both artificial membranes (Kajiya et al 2002;Kumazawa et al 2004;Tamba et al 2007;Kamihara et al 2008;Iftime et al 2010) and cell lines (Kanupriya et al 2006;Verstraeten et al 2008) and the results showed that flavonoids induced changes at the cell membrane level that lead to an increased protection against oxidative stress.…”