Antinociceptive and anti-inflammatory effects of the essential oil from Eremanthus erythropappus leaves

The chemical composition of the essential oil from air-dried leaves of Eremanthus erythropappus was studied. The main compounds were β-pinene (23.24%), β-caryophyllene (22.92%), β-myrcene (10.03%) and germacrene D (9.40%). The essential oil had an LD50 of 2.90 gkg−1 in mice. Doses of 200 and 400 mgkg−1 inhibited 10.69% and 27.06% of acetic-acid-induced writhing in mice, respectively. In the formalin-induced nociception test in mice, the essential oil inhibited the first phase of paw licking by 29.13% (400 mgkg−1) and the second phase by 32.74% (200 mgkg−1) and 37.55% (400 mgkg−1). In the hot-plate test in mice, doses of 200 mgkg−1 and 400 mgkg−1 significantly increased the reaction time after 30, 60 and 90 min of treatment. Doses of 200 and 400 mgkg−1 inhibited carrageenan-induced paw oedema in rats by 15.18% and 36.61%, respectively. Doses of 200 and 400 mgkg−1 administered 4 h before intra-pleural injection of carrageenan significantly reduced exudate volume (by 20.20% and 48.70%, respectively) and leucocyte mobilization (by 5.88% and 17.29%, respectively). These results demonstrate that E. erythropappus has analgesic and anti-inflammatory properties, supporting the use of this plant in folk medicine.