Antiplatelet effect of lonchocarpin and derricin isolated from Lonchocarpus sericeus

Abstract

In this work, we studied the effects of lonchocarpin (LCC) and derricin (DRC), two chalcones isolated from the hexane fraction of roots from Lonchocarpus sericeus (Poir.) Kunth (Fabaceae), on human platelet aggregation induced by a variety of agonists. LCC and DRC (200 and 400 μg/ml) significantly inhibited in a dose-dependent manner adenosine 5′-diphosphate (ADP)-, arachidonic acid (AA)-, thrombin (THR)-, collagen (COL)-, and adrenalin (ADR)-induced aggregation. Neither LCC nor DRC had their effects potentiated after association with L-arginine (L-ARG), a NO donor, when the inducer was ADP. In contrast, the addition of LCC or DRC to pentoxifylline (PTX), a known phosphodiesterase inhibitor, caused a significant potentiation of platelet inhibition (41.1% and 47.4%) when compared with LCC (20.3%) or DRC (17.9%) alone. The addition of aspirin or yohimbine (YOH) to LCC or DRC did not change their effects on platelet aggregation induced by AA or ADR, respectively. These results suggest that the antiplatelet effect of LCC and DRC may be mediated mainly by phosphodiesterase activity inhibition or elevation of adenosine 3′:5′-cyclic monophosphate (cAMP) and guanosine 3′:5′-cyclic monophosphate (cGMP) intracellular levels or even by inhibition of thromboxane (TX) formation, as these two substances inhibited the aggregation induced by AA, COL, and THR. © 2005 Taylor & Francis Ltd.