Anti-nociceptive substances from the roots of Angelica acutiloba.

Anti-nociceptive constituents of the Chinese crude drug Toki (the roots of Angelica acutiloba var. acutiloba Kitagawa) were investigated by means of chemical fractionation and bioassay. Seven active compounds that inhibit AcOH-induced writhing in mice have been isolated from Toki for the first time and identified as falcarinol, falcarindiol, falcarinolone (polyacetylenes), choline, scopoletin, umbelliferone and vanillic acid. Among these, the three polyacetylenes were found to be most active in the writhing test. Falcarindiol and choline also showed anti-nociceptive activities in the retrograde injection test of bradykinin into a carotid artery on rats.