Acetylcholinesterase activity inhibition by epigallocatechin gallate. A Biophysical Study.

SALAZAR PB; MINAHK CJ; DE ATHAYDE MONCORVO COLLADO A

San Miguel de Tucumán

Congreso; XLV Reunión Anual de la Sociedad Argentina de Biofísica; 2016

Polyphenols are plant secondary metabolites characterized by the presence of phenolic groups. These compounds display a myriad of different properties, among them the modulation of some enzyme activities was reported. In this regard, we previously demonstrated that epigallocatechin gallate (EGCG) inhibited the erythrocyte acetylcholinesterase activity (AChE) and proposed that red blood cell AChE may serve as a good model of the isoform present in the central nervous system. The scope of the present work was to study the influence of ionic strength in the inhibition of the membrane-bound AchE by EGCG. Besides, we analyzed how NaCl regulated the interaction of EGCG with erythrocyte membranes and attempted to correlate these findings with the enzyme activities measured in the presence and the absence of EGCG. Our results reveal that EGCG preferentially acted on the membrane-bound enzyme rather than on its soluble form. Actually, it was shown that this flavonoid may bind to the red blood  cell membrane surface, which might improve the interaction between EGCG and AChE. The EGCG binding to the ghost membrane surface was studied by measuring the steady-state DPH fluorescence anisotropy and analyzing the laurdan generalized polarization. In addition, EGCG binding to ghost surface was estimated by following the quenching of octadecyl rhodamine fluorescence. We were able to demonstrate that EGCG-membrane interaction was enhanced at higher NaCl concentrations. However, EGCG would not get inserted into the hydrophobic core of the membrane since no significant changes in the fluorescence anisotropy was detected. It can be concluded that EGCG would  interact mainly with the membrane surface, which could be correlated with the greater inhibition of AChE in this condition.