Analgesic activity of affinin, an alkamide from Heliopsis longipes (Compositae)

Heliopsis longipes (Compositae) is a Mexican plant used as analgesic in pain toothache. A solution of 10 μg/ml of dichloromethane extract from this plant showed analgesic activity determined by means of GABA release in mice brain slices. Through a bioassay-directed separation, fractions G-1, G-2, G-4 and G-6 at the same concentration were active. Affinin was the unique and common active compound, and evoke the GABA release 0.5 min after administration at 1 × 10−4 M concentration. Inactive compound were undeca-2E-en-8,10-dyinoic acid isobutylamide, hinokinin, 2′-hydroxyhinokinin, 3β-sn-glyceroyl-(1″-palmitoxy)urs-12-ene, 13(18)-ursen-3β-ol, 13(18)-ursen-3β-acetate, β-sitosterol and stigmasterol. The analgesic activity of Heliopsis longipes could be associated to affinin.