A 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.
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