Chiral 3,3'-(1,2-ethanediyl)-bis[2-(3,4-dimethoxyphenyl)-4-thiazolidinones] with anti-inflammatory activity. Part 11: evaluation of COX-2 selectivity and modelling

Anti-inflammatory/analgesic 3,3'-(1,2-ethanediyl)-bis[2-(3,4-dimethoxyphenyl)-4-thiazolidinones] 1, obtained as racemic mixtures (a) and mesoforms (b), have two equivalent stereogenic centres (C-2 and C-2') and exist as RR, SS and RS isomers. The enantioseparation of 1a provided the single enantiomers that displayed different in vitro cyclooxygenase-1/cyclooxygenase-2 selectivity ratios. In particular the dextrorotatory compound is a highly selective COX-2 inhibitor and the levorotatory one is moderately selective. Instead, RS-meso isomer (1b) exhibited similar levels of inhibitory activity on both COX isozymes. The diastereo- and enantioselectivity has been explained by molecular modelling of RR, SS and RS compounds into COX-1 and COX-2 binding sites. Theoretical results indicated SS>RS>RR affinity order towards COX-2 isoenzyme, in agreement with in vitro and previous in vivo pharmacological results.