Abstract

Platelet aggregation is one of the major causes of cardiovascular diseases. Our search for bioactive molecules from nature, led to the isolation of betulinic acid (BA) and structural modification of BA to 3β-acetoxybetulinic acid (BAA). Both inhibited blood platelet aggregation induced by thrombin, adenosine diphosphate (ADP) and epinephrine. BAA showed an enhance inhibition of platelet aggregation, in the thrombin-induced platelet aggregation (54.5±0.01 at 1 mg/ml, 63.5±0.17 at 3 mg/ml and 73.5±0.15 at 10 mg/ml; IC₅₀ 0.81 mg/ml) which was observed to be significantly (p<0.05) similar to that of the standard aspirin (65.4±0.07 at 1 mg/ml, 72.1±0.03 at 3 mg/ml and 76.5±1.22 at 10 mg/ml; IC₅₀ 0.33 mg/ml). The results clearly shows that functional group modification of BA to give BAA led to enhanced activity, hence BAA provides a better option as lead in the search for anti-platelet aggregation agents from nature.

Key words: Anti-platelet aggregation, aggregation inducer, Betulinic acid, acetoxybetulinic acid, Melalueca bracteata.