PB0827 - Flavonoid-rich plant extracts inhibit platelet aggregation induced by different reagents

Background: Blueberry (Vaccinium myrillus), blackberry (Rubus fruticosus) and wild strawberry (Fragaria vesca) have several beneficial health effects, including their antidiabetic and platelet aggregation inhibitory activities. The leaves of these plants contain remarkable amounts of flavonoids, however, their mechanism of action is yet unknown.
The effect on platelet aggregation can be measured in a clinical setting via aggregometry, using different kinds of agonists, such as collagen or adenosine-diphosphate (ADP). A glycoprotein in the venom of the south-american rattlesnake Crotalus durissus terrificus, which is available under the name Convulxin (CVX) is a potent agonist, though its mode of action is unknkown.

Aims: The goal of this study is to introduce the broad effect of the flavonoids as a new natural drug alternative using three kinds of agonists.

Methods: A mixture of blueberry, blackberry and wild strawberry leaves was extracted with hot water. After removing tannins with bovine serum albumin, the extracts were lyophilized. The snake venom was purified by multi-step gel-chromatography. Normal human plasma samples were mixed with 3.8% sodium citrate in a 1:9 ratio. Aggregometry was done using 300 μl platelet-rich plasma, with an incubation with different amounts of the extracts for 10 min at 37 °C in the aggregometer. Aggregation was measured after adding the agonists.

Results: The extract inhibited the aggregation induced by collagen, ADP and CVX in a dose-dependent manner (Figure 1). In high concentration, almost total inhibition was observed.

Conclusion(s): Flavonoid-rich plant extracts exert several beneficial health effects, including their platelet aggregation inhibitory activity. Since the effects of all three agonists were inhibited, the effect on platelet aggregation is broad, even though their mechanism of action is unknown. Our results contribute to the elucidation of the mechanism of action of Convulxin.