Antinociceptive effects of ethanolic extract from the flowers of Acmella oleracea (L.) R.K. Jansen in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: In Brazil, Acmella oleracea (L.) R.K. Jansen, popularly known as "jambu", has been used by some communities from Amazon region to treat toothache. In this study we examined the antinociceptive effect of the ethanolic extract obtained from the flowers of Acmella oleracea (EEAO) in animal models of nociceptive (chemical and thermal) and neuropathic (partial sciatic nerve ligation) pain. MATERIALS AND METHODS: Adult male mice were treated by intraperitoneal route (i.p.) with EEAO before the induction of nociceptive response by formalin, capsaicin and cinnamaldehyde, thermal heat hyperalgesia (hot plate test) and mechanical allodynia (traumatic sciatic nerve injury). Acute toxicity and non-specific sedative effects were evaluated. RESULTS: EEAO (10, 30 and 100 mg/kg) reduced both neurogenic and inflammatory phases of the formalin- and also capsaicin- and cinnamaldehyde-induced orofacial nociception. Interestingly, EEAO at 100mg/kg (i.p.) also reversed capsaicin-induced heat hyperalgesia assessed as the latency to paw withdrawal in the hot plate test. Also in the hot plate test, paw withdrawal latency was increased by EEAO (100 mg/kg) and this response was only partially reversed by naloxone. Furthermore, EEAO (100 mg/kg) also reduced mechanical allodynia caused by partial sciatic nerve ligation for 3 h. The estimated LD50 value was 889.14 mg/kg and EEAO did not alter the locomotion of animals in the open-field test. CONCLUSION: Taken together, our data show that EEAO produces prevalent antinociceptive effects and does not cause adverse effects. The presence of N-alkylamides, including spilanthol, suggests that the therapeutic effect of EEAO is related to its highest anesthetic activity.

Antinociceptive and anti-inflammatory potential of extract and isolated compounds from the leaves of Salvia officinalis in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Salvia officinalis L. has been used as a traditional herbal medicine for gastric disturbances and inflammatory processes. This study investigated the toxicological, antinociceptive and anti-inflammatory effects of the hydroalcoholic extract (HE) from leaves of Salvia officinalis and its isolated compounds in mice. MATERIALS AND METHODS: Mice were treated with HE before the induction of nociceptive response by chemical agents (acetic-acid, formalin, glutamate, capsaicin and cinnamaldehyde). Total leukocytes and plasma extravasation induced by acetic acid and paw oedema induced by glutamate, capsaicin and cinnamaldehyde were also measured. The antinociceptive effect of carnosol and ursolic acid/oleanolic acid were evaluated on formalin and cinnamaldehyde models. RESULTS: In the acute toxicity test the value of estimated LD50 for HE was 44.7579 g/kg. Oral administration of HE (10, 30 and 100 mg/kg) inhibited the number of writhings, total leukocytes and plasma extravasation induced by acetic acid. In the formalin test, HE reduced both neurogenic and inflammatory phases, effect that was affected by naloxone. The glutamate-, capsaicin- and cinnamaldehyde-induced nociception and paw oedema were reduced by HE at doses that did not affect the locomotor activity of mice in the open field test. Carnosol (10mg/kg) and ursolic acid/oleanolic acid (30 mg/kg) inhibited the inflammatory phase of formalin and the nociception and mechanical allodynia induced by cinnamaldehyde. CONCLUSIONS: These results demonstrate that HE presents significant anti-inflammatory and also antinociceptive effects on chemical behavioral models of nociception that involves an opioid mechanism. In addition, carnosol and ursolic acid/oleanolic acid contained in this plant appears to contribute for the antinociceptive property of the extract, possibly through a modulatory influence on TRPA1-receptors. However, further studies regarding the precise site and the mechanism of action of HE and carnosol and ursolic acid/oleanolic acid merited exploring further.