Potential antiinflammatory agents. II. Synthesis and structure-activity relationships of 6-chloro-5-cyclohexylindan-1-carboxylic acid (TAI-284) and related 5-substituted indan-1-carboxylic acids

Conformational analysis of some alpha-phenylpropionic acids with anti-inflammatory activity

CNDO/2 quantum mechanical conformational calculations, as well as 13C and 1H NMR measurements, have been carried out for the propionic acid residues of 2-(p-isobutylphenyl)propionic acid (ibuprofen) and 2-methyl-2-(p-isobutylphenyl)propionic acid. A relationship between the conformational angle of the propionic acid residue and the anti-inflammatory activity appears to exist. The more open the Ph--C alpha--COOH dihedral angle, the larger the anti-inflammatory activity.

Optical isomerization of R(-)-clidanac to the biologically active S(+)-isomer in guinea-pigs

Optical isomerization of clidanac (RS-6-chloro-5-cyclohexyl-1-indancarboxylic acid, I), an anti-inflammatory drug having a chiral centre in its molecule, was evaluated in guinea-pigs. After oral administration of R(-)-I, the biologically active S(+)-isomer was detectable in the plasma, in the early stages. At 3 h after dosing R(-)-I, the plasma contained above 90% of the S(+)-isomer. Little conversion of S(+)-I to R(-)-I was observed. This may account for the equivalent in vivo activities of R(-)- and S(+)-I in this species. Determination of the enantiomeric composition required derivatization of the enantiomers to their diastereomeric amides after which thin layer chromatography (t.l.c.) was used for the separation. The quantitative determination of the compounds so-separated was accomplished by in situ measurements of the u.v.-reflectance. The t.l.c.-u.v.-densitometric procedure was also used to determine the plasma concentration of I.

Inhibition of prostaglandin biosynthesis by clidanac and related compounds: structural and conformational requirements for PG synthetase inhibition

The inhibition of prostaglandin (PG) biosynthesis by clidanac (6-chloro-5-cyclohexyl-1-indancarboxylic acid, TAI-284), its metabolites and some analogues has been examined using various microsomal preparations as enzyme source. Clidanac and some analogues were among the most potent inhibitors. The (+)-isomer of clidanac was shown to be 1000 times more potent than the (-)-isomer in inhibiting PG synthetase activity. The cis-3'-hydroxyl metabolite which retains anti-inflammatory activity comparable to that of clidanac had much less inhibitory activity. Structure-activity studies with clidanac analogues showed that the position of halogen substitution in 1-indancarboxylic acid is of considerable significance for the conformational requirement for binding to the enzyme.