Background: 

Cardiovascular diseases are the leading cause of death in developed world and are progressively increasing in developing countries. Thrombosis is an important event in cardiovascular diseases causing impaired blood flow to heart and ischemic injury which leads to myocardial infarction. Inhibitors of platelet aggregation and coronary vascular leakage can provide protection against acute coronary syndrome. Blepharis edulis (BE) is used as traditional medicament in south eastern Asia for respiratory and inflammatory ailments. The aim of the present study was to analyse the anti oedematous, anti inflammatory and anti-platelet properties of B. edulis.

Methods: 

The in vitro effects of alcoholic extract of B. edulis were analysed on isolated perfused rat hearts, cultured human umbilical vein endothelial cells (HUVEC), and freshly isolated human platelets. Myocardial water contents were used as measure of coronary vascular leakage, macromolecular permeability was measured by analysing the flux of labelled-albumin and platelet aggregation was analysed by aggregometric analysis.

Results: 

Normoxic perfused rat hearts showed basal myocardial water contents of 4.50±0.7 ml/g (n=6; p<0.05, for all further parameters) dry weight which was increased to 5.54±0.8 ml/g under ischemia-reperfusion. This increase in myocardial water content was completely abolished when hearts were perfused with BE extract (50 mg/ml) during reperfusion. Similarly BE extract reduced basal permeability of HUVEC monolayers and abrogated thrombin-induced hyperpermeability. Furthermore, BE increased intracellular levels of cAMP and barrier protective effects of BE were partially blocked by a PKA inhibitor, PKI. Additionally, BE inhibited platelet aggregation induced by epinephrine and ADP in a concentration dependent manner producing half-maximal effect with 50 mg/ml. The maximum effect was achieved with 100 mg/ml where it inhibited about 80% of the platelet aggregation. Similarly, it also inhibited Ca2+ ionophore (A23187)-induced platelet aggregation, indicating a Ca2+-dependent phenomenon.

Conclusion: 

The results of present study show that the alcoholic extract of B. edulis has barrier stabilizing and strong anti-platelet aggregation activity. This activity is at least in part dependent on cAMP and its interference with Ca2+ signalling, although the precise mechanism is still unknown. Further analysis of the components of B. edulis extract can provide valuable information that can be used to treat vascular ailments like myocardial oedema and atherosclerosis.