Synthesis and in Vitro Activity of Various Derivatives of a Novel Thromboxane Receptor Antagonist, (+/-)-(5Z)-7-bicyclohept-2-exo-yl>heptenoic Acid

Article abstract of DOI:10.1021/jm00117a028

Several sulfonyl derivatives (13a-t) of (+/-)-(5Z)-7-(3-endo-amonobicyclo<2.2.1>hept-2-exo-yl)heptenoic acid (VI) were synthesized via its methyl ester 10.Sulfonylation of 10 with 11a-t followed by saponification yielded 13a-t.Inhibitory concentrations (IC₅₀) of the corresponding sodium salts 14a-t for platelet aggregation were measured with rat washed platelets (WP) and rabbit platelet-rich plasma (PRP).IC₅₀ values of some derivatives for contraction of the rat aorta were also measured.The IC₅₀ values for rat WP increased from 2.9 to 26 nM in the order of 14a, 14c, 14d, and 14b for derivatives with an arylsulfonyl residue, depending on the number of interventing methylene groups.Methyl derivative 14e exhibited a higher IC₅₀ value than n-hexyl derivative 14f.Substitution with a p-methyl-, p-fluoro-, or p-chloro group in 14a retained or slightly reduced its IC₅₀ value, while a p-n-pentyl or p-oxycarbonyl group augmented it significantly.The representative 14a supressed (15S)-15-hydroxy-11,9-(epoxymethano)prosta-5(Z),13(E)-dienoic acid (U-46619) induced aggregation of human WP with an IC₅₀ value of 7.7 nM, which corresponds well to the IC₅₀ value of 3 nM obtained for each displacement by 14a of <3H>-U-46619 or (5Z,15ξ)-9α,11α-(dimethylmethano)-15-hydroxy-16-(3-<125I>iodo-4-hydroxyphenyl)-17,18,19,20-tetranor-13-aza-11a-carbathrombo-5-enoic acid (<125I>-PTA-OH) bound to human WP.Synthesis of thromboxane A₂ (TxA₂) in human WP stimulated by thrombin was not inhibited by 14a at a concentration up to 10 μM.From these observations, the corresponding acid 13a (S-145) was concluded to be potent TxA₂ receptor antagonist.