This study investigated the analgesic and anti-inflammatory effects of an ethanol extract of Dunaliella salina Teod. (Chlorophyceae) (EDS) in Imprinting Control Region mice. Standard all-trans-β-carotene and the amount of all-trans-β-carotene in an EDS were analyzed by high-performance liquid chromatography (HPLC). In HPLC analysis, the fingerprint chromatogram of EDS was established. Both all-trans-β-carotene and EDS showed similar peaks at the retention time of 24 min. This implied that EDS contained the active ingredient all-trans-β-carotene.
Treatment of animals with EDS significantly inhibited the numbers of acetic acid-induced writhing responses at doses of 0.5 g/kg (P < 0.01), 1.0 g/kg (P < 0.001) and 2.0 g/kg (P < 0.001). This inhibitory effect of EDS (1.0 and 2.0 g/kg) on acetic acid-induced writhings was similar to that of the positive control indomethacin (10 mg/kg) (P < 0.001). EDS did not significantly inhibit the formalin-induced pain in the early phase; however, at doses of 0.1 g/kg (P < 0.01), 0.5, 1.0 and 2.0 g/kg, EDS significantly inhibited the formalin-induced pain in the late phase (P < 0.001). Finally, EDS at doses of 1.0 and 2.0 g/kg also inhibited the development of paw edema induced by λ-carrageenan (carrageenan). EDS (1.0 and 2.0 mg/kg) decreased the level of nitiric oxide (NO) in edematous paw tissue and in serum level, and diminished the level of serum tumor necrosis factor-α (TNF-α) at the fifth hour after carrageenan injection. Based on these findings, EDS probably exerts anti-inflammatory effects by suppressing TNF-α and NO. These results suggest that EDS might be a potential pharmacological analgesic and anti-inflammatory agent.