KESAN KARDIOVASKULAR IN VITRO CENTELLA ASIATICA (L.) URBAN
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Date
2003-03
Authors
HAY, CHAN SUE
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Abstract
Screening of the Centella asiatica (L.) Urban methanol extract caused vasodilatation
in response to noradrenaline-induced contraction in aortic strips and inhibited
inotropic effect of isoprenaline in the left atria, isolated from adult, male Sprague-
Dawley rats. In the right atria, the inotropic effect of isoprenaline was not affected by
the extract. Consequently, the petroleum ether fraction, chloroform fraction, butanol
fraction, and aqueous fraction obtained from cold maceration of methanol extract
were screened with the ·above experimental models. The chloroform fraction was
found to be the most potent in inhibiting the activity of aortic strip and left atria
preparations.
Therefore, the chloroform fraction was subjected to further fractionation via the
conventional gel column chromatography eluted with a series of solvent mixtures.
The eluent was collected and grouped into five major chloroform sub-fractions: CFl,
CF2, CF3, CF4, and CF5. Again each chloroform sub-fraction was individually
sc.r utinized for cardiovascular activities with the above-mentioned methods at fixed
concentrations of 0.13mg/ml, 0.25mg/ml, and 0.50mglml for comparison purposes.
Results derived from the isolated atria preparations found chloroform sub-fraction
CF2 to be the most potent in inhibiting the inherent spontaneous contraction of right
atria and the electrically-stimulated contraction of left atria. Unlike the right atria, the
inotropic effect of isopr~naline was most potently inhibited by chloroform subfraction
CF4 in the left atria. The results also showed that CF4 is the most potent
chloroform sub-fraction in vasodilating the isolated aortic strips.
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Thus, prompting further fractionation of the chloroform sub-fraction CF4 into three
other main sub-fractions (CF4a, CF4b, and CF4c) with the conventional gel column
chromatography. Vasodilatation was most prominently seen in sub-fraction CF4b
indicating that the active ingredient responsible would be found in this sub-fraction.
The mechanisms of action of the above fractions most likely involved a.1-adrenoceptor
inhibition, inhibition of the renin-angiotensin system, release of EDRF, and/or direct
vasodilatation. A further qualitative investigation into the existing compounds found
in the chloroform sub-fraction CF4b via thin layer chromatography (TLC) revealed
the possibility of the presence of flavonoids, bitter drugs, and terpenoids
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KESAN KARDIOVASKULAR IN VITRO CENTELLA ASIATICA (L.) URBAN