(1a,14a,16b)-20-Ethyl-1,14,16-trimethoxyaconitane-4,8,9-triol 4-(2-acetylamino)benzoate)

BeschreibungA highly toxic aconitine alkaloid present in Aconitum leucostomum and A. septentrionale Koelle, lappaconitine crystallizes in hexagonal tablets for whichtwo melting points have been recorded. It has [α]D + 22.3° (C6H6) or [α]18D + 27.0° (CHC1 3). The early view that a methylimino group is present has been shown to be erroneous. No crystalline salts are known but the diacetyl derivative forms colourless crystals, m.p. l25-7°C. The base is only sparingly soluble in H20 and most organic solvents, but dissolves readily in CHC1 3.Boiling the alkaloid with dilute H2S04 in a stream of H2 yields acetic acid and anthranoyllappaconine, C30H4207N2, which forms colourless rhombic tablets, m.p. 146-9°C;[α]25D + 22.07° (C6H6), giving a platinichloride tetrahydrate as brown needles, m.p. 300-31 O°C (dec.). When hydrolyzed with HCl, the base furnishes acetic and anthranilic acids and lappaconine, m.p. 96°C; [α]25D + 22.41°, giving a crystalline hydrochloride, m.p. 246-7°C and the aurichloride monohydrate, m.p. l26-7°C. Alkaline hydrolysis, on the other hand, furnishes lappaconine and lappaconitic acid (acetylanthranilic acid). From these observations, it is clear that only one hydroxyl group is associated with an acyl group in the molecule.Pharmacologically, lappaconitine is toxic although its action is less pronounced than that of aconitine (q.v.). Toxic doses produce respiratory paralysis and have a direct action upon the heart often terminating in ventricular fibrillation.