A Novel Class of Platelet Activating Factor (PAF) Antagonists. I. Synthesis and Structure-Activity Studies on PAF-Sulfonamide Isosters

Abstract

New platelet activating factor (PAF) antagonists, 3 were synthesized by replacing the charged phosphate and trimethylammonium moieties with sulfonamide and heterocyclic quarternary ammonium functionalities, respectively(PAF-sulfonamide isosteres). Darmstoff phosphatidic acid analogues of this class (Darmstoff-sulfonamide isosteres), 6 were also synthesized.The activity of these compounds as PAF antagonists was evaluated from their in vitro inhibitory effect on PAF-induced platelet aggregation in rabbit platelet-rich plasma. Among the compounds tested, some of the 2-methoxypropane derivatives with an octadecylcarbamoyloxy or octadecylcarbamoylthio side chain at the 1-position and a propylsulfonamide function bearing a terminal polar substituent such as a quarternary quinolinium or substituted quinolinium group at the 3-position were found to be the most potent (IC₅₀=0.3-0.6μM).