Fluorine bearing sydnones with styryl ketone group: synthesis and their possible analgesic and anti-inflammatory activities.

In continuation of structure activity relationship studies, a panel of fluorine containing sydnones with styryl ketone group 4-[1-oxo-3-(substituted aryl)-2-propenyl]-3-(3-chloro-4-fluorophenyl)sydnones 2a-i, was synthesized as better analgesic and anti-inflammatory agents. The title compounds were formed by condensing 4-acetyl-3-(3-chloro-4-fluorophenyl)sydnone with various substituted aryl aldehydes, characterized by spectral studies and evaluated at 100 mg\kg b.w., p.o. for analgesic, anti-inflammatory and ulcerogenic activities. Compounds 2c and 2e showed good analgesic effect in acetic acid-induced writhing while none showed significant activity in hot plate assay in mice. In carrageenan-induced rat paw oedema test, compound 2c and 2f exhibited good anti-inflammatory effect at 3rd h, whereas compounds 2c, 2e, 2d, 2g and 2h showed activity in croton oil induced ear oedema assay in mice. Compounds 2c and 2e were less ulcerogenic than ibuprofen in rats, when tested by ulcer index method. Compounds with electron attracting substituents such as 2c and 2e were found to be promising in terms of the ratio of efficacy and adverse effect. These compounds generally exhibited better activity than those of earlier series signifying fluorine substitution.