Synthesis and digestibility inhibition of diarylheptanoids: Structure-activity relationship

(+/-)-5-Hydroxy-1,7-bis-(4'-hydroxyphenyl)-3-heptanone (2a), (+/-)-5-hydrox yl-1-(4'-hydroxyphenyl)-7-phenyl-3-heptanone (2b), (+/-)-5-hydroxy-7-(4'-hy droxyphenyl)-1-phenyl-3-heptanone (2c), and (+/-)-5-hydroxy-1,7-bis-(phenyl )-3-heptanone (2d) have been synthesized to study the structure-activity re lationship regarding digestibility inhibition in vitro in cow rumen fluid. The activities were compared with the activity of chiral (S)-2a and its glu coside platyphylloside (1), isolated from Betula pendula. Compound 2a was s lightly less active, 2b and 2c were more active, and 2d was less active tha n (S)-2a and platyphylloside.