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.
This study aimed to assess the possible topical antinociceptive activity of Vanillosmopsis arborea Baker essential oil (EOVA) and to clarify the underlying mechanism, using the acute model of chemical (eye wiping) nociception in mice. EOVA (25 to 200 mg/kg; p.o. and topical) evidenced significant antinociception against chemogenic pain in the test model of formalin-induced neuroinflammatory pain. Local application of 5 M NaCl solution on the corneal surface of the eye produced a significant nociceptive behavior, characterized by eye wiping. The number of eye wipes was counted during the first 30 s. EOVA (25, 50, 100, and 200 mg/kg; p.o. and topical) significantly decreased the number of eye wipes. Naloxone, yohimbine, L-NAME, theophylline, glibenclamide, and ruthenium red had no effect on the antinociceptive effect of EOVA. However, ondansetron, p-chlorophenylalanine methyl ester (PCPA), capsazepine, prazosin, and atropine prevented the antinociception induced by EOVA. These results indicate the topical antinociceptive effect of EOVA and showed that 5-HT, α1, TRPV1, and central muscarinic receptors might be involved in the antinociceptive effect of EOVA in the acute corneal model of pain in mice.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.