ASSESMENT OF PLATELET ANTIAGGREGANT ACTIVITY OF A FRACTION FROM AN ETHANOLIC EXTRACT OF THE BARK OF Nectandra amazonum Nees

Abstract

This study shows the antiplatelet effect of the ethanolic fraction obtained from the bark of Nectandra amazonum Nees. [N.V. “laurel amarillo”, Lauraceae] applying the Born turbidimetric method. The screening test compared the fraction of N. amazonum (0.1 mg/mL), acetylsalicylic acid (ASA 0.5 mM, as reference standard) and the DMSO (0.1%, as control) in human platelets stimulated with adenosine diphosphate (ADP 2 µM), epinephrine (EPI 2 µM), collagen (COL 1 µg/mL) and arachidonic acid (AA 0.2 mg/mL). Subsequently, the study focused to determine the antiaggregant potency of the fraction throw concentration - response curves (from 1 µg/mL to 0.4 mg/mL), obtaining the pIC50 (-log IC50) values against these platelet agonists. The results showed that whereas the control platelets attained higher percentage values of aggregation (96% AA, 89% EPI, 85% COLL, 77% ADP). N. amazonum fraction significantly reduced these effects (6% AA, 45% EPI, 10% COLL, 21% ADP), near to that obtained with ASA (17% AA, 21% EPI, 10% COLL, 20% ADP). According to concentration - response curves, the pIC50 values of the fraction gave the following order of potency: AA, 4.90 > ADP, 4.51 > COLL, 4.33 > EPI, 3.85. These results suggest that N. amazonum Nees. ethanolic fraction elicit antiplatelet effects specially related to the inhibition of arachidonic acid pathway.