A study was conducted to examine the effect on homologous PCA in rats of 14 different, newly synthesized compounds, given orally, in relation to the chemical structure of DSCG, when given orally on homologous PCA in rats. The structure-activity relationship of these compounds was also discussed. Among the 7 compounds of the glycerol bischromenonyl ether derivatives, 1,3-bis (2-phenyl-4-chromenon-5-yl) oxypropane-2-ol (compound 1) showed the most potent inhibitory activity on PCA. The other compounds showed a moderate or no effect. Two compounds of glycerol bisphenyl ether derivatives had little effect. On the other hand, 1,3-bis (2-carboxy-3-hydroxyphenyl)oxypropane (compound 11) out of alkandiol bisphenyl ether derivatives significantly inhibited PCA, and the other 4 compounds showed a tendency toward inhibition of the reaction. The late inhibition, seen in the biphasic inhibitory pattern induced by compound 11, may be caused by a certain active substance transformed in the body.