Central and peripheral antinociceptive activity of 3-(2-oxopropyl)-3-hydroxy-2-oxindoles.

Convolutamydine A has been shown to develop a significant antinociceptive effect. Here we demonstrated that new analogues (5-iodo-3-(2-oxopropyl)-3-hydroxy-2-oxindole (5-Iisa), 5-fluoro-3-(2-oxopropyl)-3-hydroxy-2-oxindole (5-Fisa), 5-chloro-3-(2-oxopropyl)-3-hydroxy-2-oxindole (5-Clisa) and 5-methyl-3-(2-oxopropyl)-3-hydroxy-2-oxindole (5-Meisa)), at 0.1-10mg/kg doses, have significant peripheral and central antinociceptive effects in thermal and chemical models of nociception. Oral administered analogues demonstrated more pronounced antinociceptive effects than that obtained with the classical opioid drug morphine (5mg/kg) in the first and second phases of formalin-induced licking. In the tail flick model, 5-Clisa and 5-Meisa antinociceptive effect was almost twice as that observed with the same dose of morphine. The concomitant administration of diverse antagonists and the analogues indicates that 5-Iisa effects involve the activation of opioid pathway. On the other hand, 5-Fisa and 5-Clisa have the participation of opioid, nitrergic, cholinergic adrenergic and serotoninergic pathways and 5-Meisa has the involvement of opioid, serotoninergic and cholinergic pathways. In conclusion, our results suggest that the new four analogues from Convolutamydine A have significant antinociceptive effects in thermal and chemical induced nociception and could be used in development of new drugs to be used in pain treatment with reduced side effects.