Three new arylobenzofurans from Onobrychis ebenoides and evaluation of their binding affinity for the estrogen receptor.

Three new 2-phenyl-benzofurans, ebenfuran I, ebenfuran II, and ebenfuran III, were isolated from Onobrychis ebenoides. Their structures were elucidated on the basis of chemical and spectral data as 2-(2,4-dihydroxyphenyl)-5-hydroxy-6-methoxy-benzofuran (1), 2-(2,4-dihydroxyphenyl)-3-formyl-4-hydroxy-6-methoxy-benzofuran (2), and 2-(2, 4-dihydroxyphenyl)-3-formyl-4-hydroxy-6-methoxy-5-(3-methyl-buten- 2-y l)-benzofuran (3). The affinity of these compounds for the estrogen receptor was studied using a receptor-binding assay.