摘要Objective:To clarify the active constituents of the heartwoods of Caesalpinia sappan,a traditional Chinese medicine with the functions of promoting blood circulation (Huoxue in Chinese) and removing blood stasis (Quyu in Chinese).Methods:The chemical constituents were isolated and purified by combination of silica gel and Sephadex LH-20 column chromatography,along with semipreparative HPLC.Their chemical structures were established by multiple spectroscopic methods and comparison with literature data.The in vitro antiplatelet aggregation activities were evaluated using mouse platelet induced by AYPGKF-NH2,a gold agonist of protease-activated receptor 4 (PAR4).Results:Two new phenols,methyl 2-(4,4',5'-trihydroxy-2'-(methoxymethyl) biphenyl-2-yloxy) acetate (1)and 1'-methylcaesalpin J (2),together with 24 known compounds (3-26),were isolated from the heartwoods of C.sappan.Among them,sappanchalcone (16) and brazilin (20) showed inhibitory activities against mouse platelet aggregation with IC50 values of 114.8 μmol/L and 100.8 μmol/L,respectively.Conclusion:Antiplatelet compounds from C.sappan targeting at PAR4 are reported for the first time.