COMPARATIVE STUDY OF ANTIPLATELET ACTIVITY OF
Transcrição
COMPARATIVE STUDY OF ANTIPLATELET ACTIVITY OF
COMPARATIVE STUDY OF ANTIPLATELET ACTIVITY OF TINCTURES FROM Operculina macrocarpa (TOM), Convolvulus scammonia (TCS) AND AGUARDENTE ALEMî AND VASODILATOR ACTIVITY OF TOM IN RAT AORTA RODRIGUES, R. C. M.2([email protected]), PIERDONÁ, T. M.2, LIMA, N. R.1, ROCHA, T. M.1, SILVEIRA, E. R.3, PIRES FILHO, J. T.1, SILVA, A. H. 1, FONTENELE, J. B., VIANA, G. S. B., LEAL, L. K. A. M.1 1 Departments of Pharmacy, 2Physiology and Pharmacology, 3Organic Chemistry; Federal University of Ceara. Fortaleza - Ceara, Brazil. Keywords: Operculina macrocarpa; “Jalapa brasileira”; Convolvulus scammonia; Antiplatelet activity; Aguardente Alemã®; HPLC. 1. Introduction The tinctures of Operculina macrocarpa (“Jalapa brasileira”) and Convolvulus scammonea (“Escamônia”) are the constituents of Aguardente Alemã® (AAL), a phytomedicine indicated as laxative by pharmaceutical industries, although its main use in folk medicine is as antithrombotic (CARVALHO et al., 2003). The aim of this study was to compare the in vitro antiplatelet activity of the AAL and tinctures of O. macrocarpa (TOM) and C. scammonea (TCS) in human plasma as well as to evaluate the vasodilator action of TOM in rat aorta in vitro. 2. Methods Platelet aggregation was perfomed according to the method of Born and Cross (1963). Briefly, platelet aggregation was induced at 37ºC in an aggregometer, with stirring at 1000 rpm. The test-drugs TOM, TCS or AAL (200µg/ml) were added to platelet rich plasma 10 minutes before addition of ADP (2µM) as agonist. The resulting aggregation was presented as percent aggregation and mean ± standard deviation related to control (100%). In the evaluation of the vasodilator effect, according to Luscher and Vanhoutte (1986), cylindrical stripes of thoracic aorta were obtained from rats and bathed at 37°C (pH=7.4), aerated continuously and the tension was recorded by a force transducer connected to a register Grass (Model 5D). The control contraction was performed with KCl (60mM) and the vasorelaxant effect of TOM (11000µg/ml) was tested in aorta, with and without endothelium, contracted with KCl (60mM) and phenylephrine (PHE). Results were expressed as mean ± standard deviation for maximum vasodilator activity. The chemical analysis of TOM was performed by HPLCDAD (Alliance-Waters) through the following chromatographic conditions: analytical column RP-C18 (Varian®) and guard column (Phenomenex®), flow 1.0 mL/min, gradient elution, injection volume of 20µL, temperature 40°C, running time of 50 minutes (MICHELIN, 2008, modified). 3. Results In the study of the effects of TOM, TCS and AAL (200µg/ml) on platelet aggregation, TOM showed an inhibition of 37% (63.5 ± 3.7), while TCS and AAL did not show any antiplatelet effect (90,0 ±3,7; 99,0 ±2,6, respectively). In the evaluation of vasorelaxant activity, TOM (11000µg/ml) promoted a relaxation of the aorta pre-contracted by KCl (60mM) with or without endothelium (37.03 ± 2.79%; 31.34 ± 2.50%, respectively). In PHE 3µM pre-contrated aorta with and without endotelium, TOM also promoted a vasorelaxant effect (35.85 ± 3.92%; 40.07 ± 3.04%, respectively). Moreover, the chemistry evaluation performed by HPLC of phytochemical compounds of TOM showed the presence of gallic acid (RT: 3.023), caffeic acid (RT: 9.100) and chlorogenic acid (RT: 7.371), important markers in its composition. 4. Conclusion The study showed that only TOM has in vitro antiplatelet activity in human plasma. The results suggest that TOM has a relaxing effect on rat aorta that can be nonspecific and independent of endothelium. Further studies are needed to determine the effect of TOM with other agonists, in order to clarify its mechanism of action. Thus, analysis of chemical profile of TOM and determination of phenolic acids, as caffeic acid (Hsiao et al., 2007) showed a possible relationship of TOM and its compounds with its effect on platelets. Acknowledgments CNPq and Laboratório Ravick.