Pemencilan berpandukan aktiviti kardiovaskular in vitro ke atas tinospora crispa, miers dan aktiviti antihiperglisemiknya
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Date
2005
Authors
Bakhari, Noraziyah
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Abstract
The present study was carried out to examine the effect of Tinospora crispa
extracts on the cardiovascular system and their ability to reduce the blood glucose level.
The group of compounds or pure compounds responsible for the cardiovascular activity
were then isolated and identified through activity guided isolation procedure. The dried
powdered stems of T. crispa were serially extracted with petroleum ether, followed by
chloroform, methanol and water. The effect of these extracts on the contraction of left
and right atria, and also the aortic strips of adult Sprague-Dawley rats in vitro were
studied. Screening results showed that the chloroform extract exhibited the strongest
inhibition (82. 7 .:t._3.1% (p<0.001) of maximum response at 1.0 mg/mL) on the inotropic
effect of isoprenaline (ISP) to the left atria. The inhibition was non-competitive, since the
maximum of the log dose-response curve of the atria to ISP was reduced. However,
none of the extracts (0.2 - 1.0 mg/mL) significantly influence the inotropic activity of the
right atria to ISP. The chloroform extract was found to be most potent in inhibiting the
inherent spontaneous contraction of the right atria. All of the extracts studied also noncompetitively
inhibited the noradrenaline (NA)-induced contraction of rat aortic strips.
Chloroform extract which was again found to be most potent with 87.2_:!:2.9% (p,0.001)
inhibition at 1.0 mg/mL was separated into four fractions, Cf1, Cf2, Cf3 and Cf4 using
dry-column flash chromatography with various combinations of n-hexane, chloroform
and methanol as eluents. Screening of the chloroform fractions on cardiovascular
activities, using the same isolated tissue preparations showed that Cf3 fraction is most
potent in inhibiting the inotropic effect of ISP in left atria preparation, with 98.7 ± 1.1%
(p<0.001) inhibition at 1.0 mg/mL. Results also showed that Cf3 fraction is the most
active chloroform fraction in inhibiting noradrenaline-induced contraction of the isolated
aortic strips, where 1.0 mg/mL of the fraction inhibited 98.6 :!: 0. 7% (p<0.001) of
contraction. The isolation of the constituents in the most active fraction (Cf3) using
various chromatography techniques such as thin layer chromatography, column
chromatography and high perfomance liquid chromatography revealed the presence of
the N-acylaporphlne alkaloids namely N-formylnornuciferine and N-acetylnornuciferine
as the major compounds. A small amount of an oxoaporpine alkaloid, lysicamine was
also isolated. Other compounds that have been isolated include a long chain aliphatic
alcohol and n-tetracosyl trans-ferulate. Structural identification of the compounds is
based on spectral analysis such as NMR, UV, IR and GC-MS. The hypoglycaemic effect
of all T. crispa extracts i.e petroleum ether, chloroform, methanol and aqueous extracts
on normal and diabetic adult Spraque-Dawley rats were also studied. However, none
the extracts significantly reduced the blood glucose level in both normal and diabetic
rats. All the extracts did not significantly influence the glucose tolerance in normal rats
as shown by the glucose tolerance test.
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Keywords
Kardiovascular , Tinospora crispa , Antihiperglisemiknya