Antithrombotic, anticoagulant and antiplatelet activity of betulinic acid and 3β-acetoxybetulinic acid from Melaleuca bracteata 'Revolution Gold' (Myrtaceae) Muell leaf

Purpose: To investigate the antithrombotic, anticoagulant and antiplatelet activity of betulinic acid (BA) and 3 beta-acetoxybetulinic acid (BAA) from Melaleuca bracteata 'Revolution Gold'. Methods: Betulinic acid was isolated from the ethyl acetate extract of M. bracteata leaves by column chromatography, from which BAA was subsequently synthesized by acetylation. Structural elucidation of the compounds was conducted using mass spectrometry (MS), infra-red (IR) spectroscopy and nuclear magnetic resonance (NMR). The antithrombotic potential of the compounds was assessed using chromogenic substrate. Anticoagulation studies were carried using bleeding tail time assay in a rat model. Plasma-rich platelets from rats were employed for platelet aggregation studies using light microscope. Results: The compounds significantly (p < 0.05) showed antithrombotic activities in a dose-dependent manner. BAA showed significantly (p < 0.05) higher half-maximal concentration (IC50) value of 1.10 +/- 0.03 mg/mL than BA (2.36 +/- 0.09 mg/mL) and aspirin (2.65 +/- 0.01 mg/mL) which served as positive control. The compounds exhibited anticoagulation activity with poor bleeding time, compared to aspirin. Likewise, the compounds attenuated platelets aggregation induced by thrombin. Conclusion: BAA displays better antithrombotic, antiplatelet, and anticoagulant activities than BA. Therefore, it may be a promising remedy for the management of cardiovascular events.