5—(2-Carboxyl substituted phenoxy)furan-2-carboxylic acids( I) were cyclized in the presence off poly phosphoric acid ethyl ester (PPE) to afford a series of substituted ethyl furo[2,3-b]chromone2-carboxylates (8a -81). All of the carboxylate derivatives exhibited slight anti-allergic activity but diid not inhibit PMA-induced superoxide formation or PAF – and thrombin-induced platelet aggre. Gation. On the contrary, they weakly inhibited fMLP-induced superoxide formation. Furthermoore, compounds 8a and 8d significantly inhibited AA-induced platelet aggregation, whereas compound 8k inhibited AA- and collagen-induced platelet aggregation. The preliminary structure-activity relation ofthese furo[2,3-b]chromone-2- carboxylates was examined. A –Br or –CH3 at position 6 was favorable for antiplatelet activity against AA-induced platelet aggregation, while –Cl , -I, or –OCH3 was unfavorable. In addition, introduction of –Br or – OCH3 at position 6 and–CH3 at position 8 resulted in increased inhibitory activity against collagen-induced platelet aggregation. ; 藥理學科暨研究所 ; 醫學院 ; 期刊論文