Ethnopharmacological relevance: Heliopsis longipes (A. Gray) Blake (Asteraceae) is a broadly used species in the Mexican, Central and South American Traditional Medicine for its anaesthetic, analgesic, anti-inflammatory and anti-ulcerative properties. The ethanolic extract contains alkamides, mainly affinin (spilanthol). This family of compounds exerts an in vitro inhibitory action on the cyclooxygenase and lipoxygenase enzymes.
Aim of the study: The present study approaches the anti-inflammatory effect of the extract and its main bioactive component affinin and derived isobutyl-decanamide.
Materials and methods: The anti-inflammatory effect was evaluated through the mouse ear oedema test by means of two irritating agents, arachidonic acid (AA) and phorbol myristate acetate (PMA).
Results: Heliopsis longipes, affinin and isobutyl-decanamide displayed a marked anti-inflammatory effect on the AA model with ED(50)=0.8, 1.2 and 0.9 mg/ear, respectively. Nimesulide (1 mg/ear) was used as a reference drug. In PMA model, the extract and two alkamides also showed a dose-dependent anti-inflammatory effect with ED(50)=2.0, 1.3 and 1.1 mg/ear, respectively. Indomethacin (3 mg/ear) was used as reference drug.
Conclusions: These results could represent an important contribution to explain the anti-inflammatory ethnobotanical effects reported for Heliopsis longipes and other species containing affinin (spilanthol). For the first time the topical anti-inflammatory effects of Heliopsis longipes, affinin and isobutyl-decanamide were studied.