A new dicoumarin and anticoagulant activity from Viola yedoensis Makino

A new dicoumarin, named as dimeresculetin (1), together with another dicoumarin, euphorbetin (2) and esculetin (3) were isolated from the ethyl acetate extract of the dried whole plants of Viola yedoensis Makino. The structure of I was elucidated as 7-hydroxy-6-[(6,7-dihydroxy-2-oxo-2H-1-benzopyran-5-yl)oxy]-2H-1-benzopyran-2-one on the basis of extensive NMR, as well as the other spectral analysis. Compounds 1-3 exhibited anticoagulant activities with respect to activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT). (C) 2009 Elsevier B.V. All rights reserved.