Studies on the constituents of Aconitum species. IX. The pharmacological properties of pyro-type aconitine alkaloids, components of processed aconite powder 'kako-bushi-matsu': analgesic, antiinflammatory and acute toxic activities.

Eight pyro-type aconitine alkaloids contained in the processed aconite powder 'Kako-bushi-matsu' were studied for their analgesic, antiinflammatory and acute toxic actions. All these compounds showed significant analgesic and antiinflammatory actions. Among the pyro-type alkaloids, 16-epi-pyrojesaconitine and pyrojesaconitine were the most potent analgesics. The analgesic activity of pyro-type aconitine alkaloids was lower than that of each of the parent alkaloids, aconitine, mesaconitine, hypaconitine and jesaconitine. However, pyro-type aconitine alkaloids had very low toxicity, and the decreasing rates of the toxicity in changing from the parent alkaloids to the pyro-type aconitine alkaloids were much larger than those relating to the analgesic activity. Eight pyro-type aconitine alkaloids were found to inhibit the carrageenin-induced hind paw edema at 2 to 6 h after the carrageenin subplantar injection. Consequently, it was demonstrated that the pyro-type aconitine alkaloids produced through the processing of raw aconite roots, 'Bushi', have a role in the medicinal effects of the processed aconite powder 'Kako-bushi-matsu'.