Membrane cholesterol content is a major factor that affects the ability of epigallocatechin gallate to inhibit AChE

SALAZAR PB; DUPUY F; DE ATHAYDE MONCORVO A; MINAHK C

Ciudad Autonoma de Buenos Aires

Congreso; Reunion Conjunta de Sociedades de Biociencias; 2017

Polyphenols areplant secondary metabolites able to interact not only with proteinsbut also with membrane lipids, what may be related with some of thebeneficial properties attributable to these compounds. We havealready demonstrated that epigallocatechin gallate (EGCG) wasefficient as acetylcholinesterase (AChE) inhibitor when the enzymewas bound to membranes. Even though EGCG was still able to inhibitAChE in its soluble form, the effect was less pronounced. In fact,the erythrocyte AChE isoform has proved to be a good model forstudying the enzymatic activity of membrane-bound AChE isoforms,hence this variant was chosen to carry out the present work. Theactivity of AChE, as well as others membrane-bound enzymes, has beenshown to depend on membrane lipid composition and order. That is tosay, membrane lipid alterations may induce changes in the activitiesof these enzymes. Therefore, we studied cholesterol-levels influencein erythrocyte membranes on the AChE inhibition by EGCG. In otherwords, we aimed to know if the interaction of EGCG with membranevaries and if it influences on AChE inhibition degree. EGCG-mediatedinhibition of enzymatic activity was enhanced when AChE was bound tomembranes with low cholesterol level. The EGCG localization wasstudied by biophysical techniques. On one hand, an enhanced quenchingof rhodamine R-18 fluorescence by EGCG, was observed when cholesterolcontent of membranes was reduced, leading us to hypothesize that EGCGmight interact with interfacial portion of membranes. On the other,possible deeper localization of EGCG in membrane was assessed by IRspectroscopy.p { margin-bottom: 0.25cm; line-height: 115%; }