Chiral resolution, configurational study and pharmacological profile of 2-phenoxypropionic acids

The racemates and several enantiomers of 2-phenoxypropionic acids, bearing alkyl, acetyl, benzyl, benzoyl, phenyl, difluorophenyl, Cl, NO2 groups on the aromatic moiety, were investigated as potential analgesic-antiinflammatory drugs. The enantiomers, whose absolute configuration has been previously determined by us, were prepared by chiral resolution of the diastereoisomeric salts of the racemates with cynchonidine. The enantiomeric excess was determined by chiral chromatography. The chiroptical properties of the dextroisomers were investigated by CD. The pharmacological properties of the racemates and the enantiomers were monitored by analgesic-antiinflammatory activity tests as well as by gastrotolerability and acute toxicity tests. Some compounds were shown to be superior to ASA and ketoprofen because they have higher or similar analgesic properties, with less gastroulcerogenetic activity. Furthermore low acute toxicity was found for the compounds with high values of ED50. Correlations between the configuration of the enantiomers and their activity are not evident. For the most active compounds, the activity of one of the enantiomers is superior to that of the racemates. This is particularly true for (S)-3, (R)-15 and (S)-18.