BACKGROUND AND OBJECTIVE: Inula helenium is a medicinal plant with proven anti-cancer, anti-microbial and anti-fungal effects. The aim of this study is to investigate the antinociceptive and anti-inflammatory effects of hydroalcoholic extract of Inula helenium leaf on male rats.

METHODS: 66 male rats were used in this experimental study. The animals were divided into 6 groups (each group consisted of 6 rats) for pain assessment tests: control group, groups treated with the extract (50, 100 and 300 mg/kg), morphine and naloxone in combination with 300 mg/kg extract. Furthermore, they were divided into 5 groups (each group consisted of 6 rats) for anti-inflammatory tests: control group, groups treated with the extract (10, 50 and 100 mg/kg) and dexamethasone. Tail-flick, rating and formalin tests were used to assess pain and xylene test was used to assess inflammation.

FINDINGS: According to the results of rating (28.21±1.34) and tail-flick (5.11±1.34) tests, using 300 mg/kg extract had significant antinociceptive effect (p<0.01) compared with control group (41.22±4.12). According to the formalin test, using 100 mg/kg extract decreased pain rating from 2.17±0.21 in control group to 0.53±0.24, in the chronic phase (p<0.05). According to the xylene test, using 50 and 100 mg/kg extract decreased the inflammation of the ear in rats (4.1±2 and 3.3±1, respectively) compared with control group (0.4±7.6) (p<0.001 and p<0.01).

CONCLUSION: Results of this study showed that hydroalcoholic extract of Inula helenium leaf may benefit from antinociceptive and anti-inflammatory effects