Antinociceptive and anti-inflammatory activities of Ayapana triplinervis essential oil rich in thymohydroquinone dimethyl ether from Brazil.

Ayapana triplinervis (M.Vahl) R.M.King & H.Rob. (Asteraceae), popularly known as japana, is a tropical, aromatic subshrub widely used as tea to combat some diseases. The essential oil was obtained from the leaves by hydrodistillation (3 h), and the chemical composition was analyzed by gas chromatography coupled to mass spectrometry. For in vivo assays, Mus musculus/Swiss mice were used to evaluate oral acute toxicological (at dose of 2000 mg/kg); peripheral and central analgesic for abdominal contortion (doses of 6.25, 12.5, 25, 50 and 100 mg/kg), hot plate test (12.5, 25, 50, and 100 mg/kg) and formalin (25, 50 and 100 mg/kg); open field test (100 mg/kg); and anti-inflammatory by ear swelling induced by xylene (6.25,12.5, 25, 50, and 100 mg/kg). The yield of A. triplinervis essential oil (AtEO) was 4.6%, and the oxygenated monoterpene 2,5-dimethoxy-p-cymene was the major compound in this study (63.6%). AtEO at a dose of 2,000 mg/kg orally did not change the behavior patterns or mortality of the animals; liver and kidney biochemical levels were similar to the control group, indicating no liver and kidney toxicity. Moreover, AtEO, at doses of 6.25, 12.5, 25, 50, and 100 mg/kg, reduced abdominal contortions by 21%, 54%, 91%, 58%, and 55%, respectively. In the hot plate test, AtEO showed a significant increase in latency time in the 60-min interval at doses of 25 mg/kg (11.3 ± 3.3 s) and 100 mg/kg (11.9 ± 0.9 s). In the first phase of the formalin test, AtEO decreased paw licking time at doses of 25, 50, and 100 mg/kg, with inhibition of 22%, 38%, and 83%; in the second phase, the same doses, decreased licking time with inhibition of 24%, 34%, and 76%. AtEO did not present a significant change in the spontaneous locomotor activity of the animals. Doses of 6.25, 12.5, 25, 50, and 100 mg/kg significantly reduced ear edema induced by topical application of xylene with percentages of 40%, 39%, 54%, 45%, and 45%, respectively. So, AtEO demonstrated low acute oral toxicity and exhibited significant antinociceptive and anti-inflammatory actions, consistent with the use of A. triplinervis in traditional medicine.
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