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.