Antinociceptive action of Vanillosmopsis arborea in male mice

OBJECTIVE

Vanillosmopsis arborea Baker (Asteraceae) has high economic value from Chapada to Araripe and its bark essential oil is a potential source of alpha-bisabolol. The present study aimed to elucidate the antinociceptive and antipruritic properties of the essential oil of V. arborea Baker (EOVA) in mice.

MATERIALS AND METHODS

The antinociceptive activity was assessed using the capsaicin, glutamate, hot plate and cold allodynia tests. The antipuritic effects were also verified based on histamine-induced scratching behavior.

RESULTS

EOVA reduced the paw licking induced by capsaicin, but not that induced by glutamate. The essential oil increased the latency time in the hot plate, attenuated the cold allodynia induced by acetone and inhibited histamine-induced scratching behavior.

CONCLUSION

The experimental data demonstrated that EOVA showed central and peripheral antinociceptive activity and antipruritic effect.

Essential oil of Lippia alba and its main constituent citral block the excitability of rat sciatic nerves

Lippia alba is empirically used for infusions, teas, macerates, and hydroalcoholic extracts because of its antispasmodic, analgesic, sedative, and anxiolytic effects. Citral is a mixture of trans-geranial and cis-neral and is the main constituent of L. alba essential oil and possesses analgesic, anxiolytic, anticonvulsant, and sedative effects. The present study evaluated the effects of the essential oil of L. alba (EOLa) and citral on compound action potentials (CAPs) in Wistar rat sciatic nerves. Both drugs inhibited CAP in a concentration-dependent manner. The calculated half-maximal inhibitory concentrations (IC₅₀) of peak-to-peak amplitude were 53.2 µg/mL and 35.00 µg/mL (or 230 µM) for EOLa and citral, respectively. Peak-to-peak amplitude of the CAP was significantly reduced by 30 µg/mL EOLa and 10 µg/mL citral. EOLa and citral (at 60 and 30 µg/mL, values close to their respective IC₅₀ for CAP blockade) significantly increased chronaxy and rheobase. The conduction velocity of the first and second CAP components was statistically reduced to ∼86% of control with 10 µg/mL EOLa and ∼90% of control with 3 µg/mL citral. This study showed that EOLa inhibited nerve excitability and this effect can be explained by the presence of citral in its composition. Both EOLa and citral showed inhibitory actions at lower concentrations compared with other essential oils and constituents with local anesthetic activity. In conclusion, these data demonstrate that EOLa and citral are promising agents in the development of new drugs with local anesthetic activity.