Antinociceptive and Anti-inflammatory Activities of the Methanolic Extract from the Stem Bark of Lophanthera lactescens.

Lophanthera lactescens is a medicinal plant commonly used in traditional medicine to relieve fever and pain in inflammatory processes. In the present study, the in vivo antinociceptive and anti-inflammatory effects of the methanolic extract from L. lactescens have been investigated. Antinociceptive activity was evaluated through writhing, formalin, and tail flick tests, while the anti-inflammatory activity was evaluated through paw oedema and air pouch tests in mice. A phytochemical analysis was performed. The extract produced significant inhibition on nociception induced by acetic acid-induced abdominal writhing, formalin, and tail flick tests, and on inflammation induced by oedema and air pouch tests. The previous administration of atropine and glibenclamide reduced the antinociceptive effect produced by the methanolic extract from L. lactescens on the tail flick test in 89% and 66%, respectively. The methanolic extract had no significant effect in the open field test. No intoxication symptoms were observed in the animals administered orally at increasing doses up to 2000 mg/kg. The methanolic extract from the stem bark of L. lactescens possesses antinociceptive properties on models of acute pain induced by chemical and thermal stimuli as well as in models of inflammation and further suggests that this anti-inflammatory activity might involve inhibition of the proinflammatory cytokines, and the antinociceptive activity might involve participation of the cholinergic system and adenosine triphosphate-dependent K+ channel.

Essential oil from Myrcia ovata: chemical composition, antinociceptive and anti-inflammatory properties in mice.

The leaves of Myrcia ovata, popularly known as "laranjinha do mato", are frequently used as an infusion in folk medicine. The essential oil obtained from these leaves is rich in citral, a mixture of neral and geranial isomers, known for its analgesic effect. Male Swiss mice (20-22 g) were tested in models of acute pain (acetic acid-induced abdominal writhing, tail flick, and formalin tests) and acute inflammation (paw oedema and air pouch tests) as well as in a model for evaluation of spontaneous motor performance (open-field test). The essential oil from M. ovata was administered orally at doses of 50-300 mg/kg. In addition, water, vehicle, morphine (5.01 mg/kg for evaluation of pain and motor performance), acetyl salicylic acid (200 mg/kg in the formalin test), and dexamethasone (2.25 mg/kg for evaluation of oedema formation, leukocyte extravasation, and quantification of cytokines) were administered. The essential oil showed a significant effect at doses of 200 and 300 mg/kg in the acute pain and acute inflammation tests. The effect of the essential oil was reduced by pretreatment with naloxone. The essential oil did not induce motor impairment. The extract was not toxic after oral administration (LD50 > 3000 mg/kg). These data provide initial evidence that the traditional use of M. ovata can be effective in reducing pain and inflammation.