Antiplatelet aggregation principles from Ephemerantha lonchophylla.

Bioactivity-directed separation led to the identification of four compounds, viz. denbinobin (1), 3,7-dihydroxy-2,4-dimethoxyphenanthrene (2), 3-methylgigantol (3), and erianthridin (4) from the ethanolic extract of Ephemerantha lonchophylla. Antiplatelet tests were carried out using 4 different aggregation inducers, viz. arachidonic acid (AA), thrombin, collagen and platelet activating factor (PAF). The results indicated that only compounds 2, 3, and 4 exhibited generally significant anti-aggregation activities with that against AA-induced aggregation being most effective. Estimated IC50, values in this regard for 2, 3, and 4 were 24 microM, 30 microM and 9 microM, respectively.