Reaction of phthalimido alkyl acids with isopropylamine: synthesis, anti-inflammatory and antinociceptive properties

Abstract

Phthalimido alkyl acids 3-phthalimidopropionic acid (2a) and 4-phthalimidobutyric acid (2b) were
treated with isopropylamine at room temperature using different solvents (dimethylformamide,
dichloromethane and methanol) as the reaction medium and afforded 3-benzamido-propionic acid –2-
(2-methylethyl)-carboxamide (3), 2-benzamido-2-methylethane-2-(2-methylethyl)-carboxamide (4), and 4
benzamido-butyric acid –2- (2-methylethyl)- carboxamide (5). Compound 4 was a dimmer that was least
expected. Compounds 3, 4 and 5 were evaluated for antinociceptive property using acetic acid-induced
writhing test. 4 exhibited the highest analgesic effect at 80 mg/kg it caused 88 % inhibition and was
more pronounced than the reference drugs (indomethacin, acetylsalicylic acid and paracetamol), 3 and
5. The anti-inflammatory activity of the compounds was also screened using carrageenan- induced rat
paw oedema assay and 4 showed higher activity than others except the reference drug. The effects
were dose-dependent.