Photophysical isomerization of liposomal bilayer-included caffeic acid phenethyl ester leading to membrane dehydration

Abstract

Caffeic acid phenethyl ester (CAPE) is well known for its prolific biological and pharmaceutical applications. There are plethora of studies on CAPE in context to antimicrobial, antiviral, anti-inflammatory and anticancer activities. It has been applied even to suppress chemotherapy-induced toxicities. However, an important property of CAPE has been so far overlooked, which is its photoinduced cis/trans isomerization. The present study has enlightened upon the detailed photophysical changes and the related physical parameters in CAPE. CAPE, being a membrane binding molecule, has been added to the hydrophobic portion of the bilayer of large unilamelar vesicles (LUVs) made from dimyristoyltrimethylammonium propane (DMTAP) lipids in aqueous buffer (pH 7.4). Absorption of light and conversion of the trans-isomers to the cis-form led to vesicular squeezing followed by expulsion of the penetrated water molecules that hydrated the liposomal membrane.

Keywords

• Liposomes
• Bilayer
• Thickness
• Caffeic acid
• Isomerization
• Dehydration