INHIBITORY ACTIVITY OF TRITERPENOIDS, EUGENOL AND EUGENOL ACETATE IN THROMBIN, ADENOSINE DIPHOSPHATE AND EPINEPHRINE-INDUCED PLATELET AGGREGATION
INHIBITORY ACTIVITY OF TRITERPENOIDS, EUGENOL AND EUGENOL ACETATE IN THROMBIN, ADENOSINE DIPHOSPHATE AND EPINEPHRINE-INDUCED PLATELET AGGREGATION
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Date
2012-11
Authors
HABILA, AMAYA JOBIN
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Abstract
Platelet hyper-aggregation is the underlying cause of cardiovascular diseases. The clinical
limitation and adverse side effect associated with currently used anti-platelet aggregation
agents have fuelled the search for more effective agents of natural origin. Oleanolic acid,
maslinic acid and eugenol from Syzigium aromaticum and betulinic acid from Melaleuca
bracteata were isolated. The isolated compounds were modified to their acetates to
mimic the functionality of aspirin. The isolated and modified compounds were
characterized using nuclear magnetic resonance (NMR) spectroscopic techniques to
ascertain the structure of the compounds. The isolated and modified compounds were
evaluated for platelet aggregation inhibition induced by Thrombin, Adenosine
diphosphate (ADP) or epinephrine. The result of the platelet aggregation inhibition using
thrombin, ADP and epinephrine as agonist on the test compounds showed that the highest
inhibition exhibited by betulinic acetate on the thrombin-induced platelet aggregation
(54.5±0.01 at 1mg/ml, 63.5±0.17 at 3mg/ml and 73.5±0.15 at 10mg/ml, IC50 0.81mg/ml)
which was similar (P<0.05) to the values of Aspirin (65.4±0.07 at 1mg/ml, 72.1±0.03 at
3mg/ml and 76.5±1.22 at 10mg/ml, IC50 0.33mg/ml) and Heparin (65.9±0.59 at 1mg/ml,
66.9±0.03 at 3mg/ml and 70.6±0.16 at 10mg/ml, IC50 0.26) used as standards.
Antioxidant activity was investigated using 1,1′-diphenyl-2-picrylhydrazyl (DPPH) and
2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS+ )) assay to suggest a
mechanism of action of the test compounds. The anti-oxidant activities of the compounds
showed that eugenol possessed significant (P<0.05) free radical scavenging activity with
highest activity in the ABTS+ assay (57.7±0.002, at 0.0625mg/100ml, 75.3±0.003, at
0.125mg/100ml, 89±0.002, at 0.25mg/100ml, 89.7±0.001, at 0.5mg/100ml, 90.7±0.001,
at 1mg/100ml and an IC50 0.05mg/100ml) which is more than those of the standards
Ascobic acid (9.7±0.001, at 0.0625mg/100ml, 19.5±0.003, at 0.125mg/100ml,
26.0±0.001, at 0.25mg/100ml, 47.7±0.001, at 0.5mg/100ml, 60.9±0.002, at 1mg/100ml
and an IC50 0.66mg/100ml) and Butylated hydroxyanisole (9.7±0.005, at
0.0625mg/100ml, 15.4±0.001, at 0.125mg/100ml, 21.9±0.002, at 0.25mg/100ml,
52.0±0.001, at 0.5mg/100ml, 65.8±0.001, at 1mg/100ml and an IC50 0.48mg/100ml))
used. The study suggests that the isolated and modified compounds be used as antiplatelet
aggregation agents in the management of blood-clotting related diseases.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE
STUDIES, AHMADU BELLO UNIVERSITY, IN PARTIAL
FULFILMENT FOR THE AWARD OF MASTER OF SCIENCE
(M.Sc) IN BIOCHEMISTRY,
Keywords
INHIBITORY, ACTIVITY, TRITERPENOIDS,, EUGENOL, ACETATE, THROMBIN,, ADENOSINE, DIPHOSPHATE, EPINEPHRINE-INDUCED, PLATELET, AGGREGATION