Abstract

Phytochemical investigation of Eucalyptus grandis, a plant with many industrial and traditional applications, led to the isolation of 3β-hydroxyurs-2-en-28-oic acid (FJ-2) and the synthesis of 3β-acetylurs-12-en-28-oic acid (FJ-6), with antiplatelet aggregation activity. Platelet aggregation was induced by thrombin a platelet protease-activated receptors subtype I and IV, adenosine diphosphate (ADP) a potent agonist to platelet G protein-coupled P2Y receptor and epinephrine. The results showed FJ-2 had the highest percentage inhibition (87.8 ± 1.81) which was observed to be significantly (P < 0.05) higher than the standards heparin (65.9 ± 0.91) and aspirin (65.4 ± 0.8) at a concentration of 1.0 mg/ml, using thrombin-as agonist. But this percentage inhibition was observed to decrease with increase in the concentration of FJ-2; this implied an optimal concentration (≤ 1.0 mg/ml) for inhibition of platelet aggregation by FJ-2, above which inhibition decreases. FJ-6 showed a dose dependent increase in percentage inhibition (51.4 ± 0.65 at 1.0 mg/ml and 73.8 ± 1.72 at 10 mg/ml). The two compounds differ only in their functionality but behave differently towards platelet aggregation inhibition. This preliminary result suggests that FJ-2 and FJ-6 may be taken as candidate lead natural compounds to be considered in the search for natural products with beneficial effects on aberrant platelet activation mediated cardiovascular disorders.

Key word: Antiplatelet aggregation, blood clot, Eucalyptus grandis and platelet agoni.