Mechanisms underlying the antinociceptive effect of mangiferin in the formalin test.

The purpose of this study was to investigate the possible antinociceptive effect of mangiferin, a glucosylxanthone present in Mangifera indica L., in inflammatory pain. Furthermore, we sought to investigate the possible mechanisms action that contributes to these effects. The ipsilateral local peripheral (1-30 µg/paw), intrathecal (1-30 µg/rat) and oral (1-30 mg/kg) administration of mangiferin produced a dose-dependent reduction in formalin-induced nociception. The antinociceptive effect of this drug was similar to that induced by diclofenac after oral and local peripheral administration. Furthermore, mangiferin was also able to reduce 0.1% capsaicin- and serotonin-induced nociceptive behavior. The local peripheral antinociceptive effect of mangiferin in the formalin test was blocked by naloxone (50 μg/paw), naltrindole (1 μg/paw), 5-guanidinonaltrindole (5-GNTI, 1 μg/paw), N(G)-L-nitro-arginine methyl ester (L-NAME, 100 µg/paw), 1H-(1,2,4)-oxadiazolo [4,2-a]quinoxalin-1-one (ODQ, 50 µg/paw) and glibenclamide (50 μg/paw), but not by methiothepin (30 μg/paw). These results suggest that the antinociceptive effects induced by mangiferin are mediated by the peripheral opioidergic system involving the activation of δ, κ, and probably µ, receptors, but not serotonergic receptors. Data also suggests that mangiferin activates the NO-cyclic GMP-ATP-sensitive K(+) channels pathway in order to produce its local peripheral antinociceptive effect in the formalin test. Mangiferin may prove to be effective in treating inflammatory pain in humans.