Platelet-activating factor (PAF) receptor binding antagonists from Alpinia officinarum

Two new compounds 6-hydroxy-1,7-diphenyl-4-en-3-heptanone ( 1) and 6-(2-hydroxy-phenyl)-4-methoxy-2-pyrone ( 4) along with three known compounds were isolated from the extracts of Alpinia officinarum under bioassay-guided purification. The isolated diarylheptanoids exhibited potent PAF receptor binding inhibitory activities. The bioassay-guided purification of ether extracts of Alpinia officinarum led to the isolation of two new compounds 6-hydroxy-1,7-diphenyl-4-en-3-heptanone ( 1) and 6-(2-hydroxy-phenyl)-4-methoxy-2-pyrone ( 4) as well as three known compounds 1,7-diphenyl-4-en-3-heptanone ( 2), 1,7-diphenyl-5-methoxy-3-heptanone ( 3), and apigenin ( 5). Their structures were established on the basis of spectral methods. All three diarylheptanoids 1, 2, and 3 exhibited potent PAF receptor binding inhibitory activities with an IC 50 of 1.3, 5.0, and 1.6 μM, respectively. These studies have identified diarylheptanoids as a novel class of potent PAF antagonists.