Aconitum napellus, monkshood,[2]aconite, Venus' chariot or wolfsbane, is a species of highly toxic flowering plants in the genusAconitum of the familyRanunculaceae, native and endemic to western and central Europe. It is an herbaceousperennial plant growing to 1 m (3 ft 3 in) tall, with hairless stems and leaves. The leaves are rounded, 5–10 cm (2.0–3.9 in) diameter, palmately divided into five to seven deeply lobed segments. The flowers are dark purple to bluish-purple, narrow oblong helmet-shaped, 1–2 cm (0.39–0.79 in) tall. Plants native to Asia and North America formerly listed as A. napellus are now regarded as separate species. The plant is extremely poisonous in both ingestion and body contact. It is the most poisonous plant in all of Europe.[3]
Aconitum napellus subsp. firmum (Rchb.) Gáyer, Central and eastern Europe (declared as an own species Aconitum firmum[7])
Aconitum napellus subsp. fissurae (Nyár.) W.Seitz, Balkans to south-western Russia
Aconitum napellus subsp. hians (Rchb.) Gáyer, Central Europe
Aconitum napellus subsp. lusitanicum Rouy, south-western Europe
Aconitum napellus subsp. superbum (Fritsch) W.Seitz, western Balkans
Aconitum napellus subsp. tauricum (Wulfen) Gáyer, Eastern Alps, southern Carpathians (declared as an own species Aconitum tauricum by other sources[8][9])
Aconitum napellus is grown in gardens for its attractive spike-like inflorescences and showy blue flowers.[10] It is a cut flower crop used for fresh cutting material and sometimes used as dried material. The species has a low natural propagation rate under cultivation and is propagated by seed or by removing offsets that are generated each year from the rootstocks. The use of micropropagation protocols has been studied.[11] This species has been crossed with other Aconitums to produce attractive hybrids for garden use, including Aconitum × cammarum.[12]
Seeds
Like other species in the genus, A. napellus contains several poisonous compounds, including enough cardiac poison that it was used on spears and arrows for hunting and battle in ancient times.[13] Persian physician Avicenna (980–1037) wrote that arrows dipped in the sap were used to kill, and Dr Antonio Guaineri, in one of the first medical dictionaries 'Practica', wrote that arrows that had the poison from roots of the plant were used to kill wild goats in Italy.[14]A. napellus has a long history of use as a poison, with cases going back thousands of years.[15] During the ancient Roman period of European history, the plant was often used to eliminate criminals and enemies, and by the end of the period it was banned and anyone growing A. napellus could have been legally sentenced to death.[16] Aconites have been used more recently in murder plots; they contain the chemical alkaloids aconitine, mesaconitine, hypaconitine and jesaconitine, which are highly toxic.[17] It was also used in a recent Sherlock Holmes book plot.[18]
Toxicology
Marked symptoms may appear almost immediately, usually not later than one hour, and "with large doses, death is almost instantaneous".[19] Death usually occurs within two to six hours in fatal poisoning (20 to 40 mL of tincture may prove fatal).[20] The initial signs are gastrointestinal including nausea, vomiting, and diarrhea. This is followed by a sensation of burning, tingling, and numbness in the mouth and face, and of burning in the abdomen.[21] In severe poisonings pronounced motor weakness occurs and cutaneous sensations of tingling and numbness spread to the limbs. Cardiovascular features include hypotension, sinus bradycardia, and ventricular arrhythmias. Other features may include sweating, dizziness, difficulty in breathing, headache, and confusion. The main causes of death are ventricular arrhythmias and asystole, paralysis of the heart or of the respiratory center.[20][22] The only post-mortem signs are those of asphyxia.[21]
Poisoning may also occur following picking the leaves without wearing gloves; the aconitine toxin is absorbed easily through the skin. In this event, there will be no gastrointestinal effects. Tingling will start at the point of absorption and extend up the arm to the shoulder, after which the heart will start to be affected. The tingling will be followed by unpleasant numbness. Treatment is similar to poisoning caused by oral ingestion and even handling the plant without gloves has been reported to result in multi-organ failure and death.[25][26]
The plant's chief toxic component, aconitine, is a potent neurotoxin that opens tetrodotoxin sensitive sodium channels.[27] It increases the influx of sodium through these channels and delays repolarization, thus increasing excitability and promoting ventricular dysrhythmias.[27]
^A. A. Watad, M. Kochba, A. Nissim and V. Gaba, "Improvement of Aconitum napellus micropropagation by liquid culture on floating membrane rafts", Journal Plant Cell Reports, Publisher: Springer Berlin / Heidelberg, ISSN0721-7714 (Print) ISSN1432-203X (online), Volume 14, Number 6 / March 1995, DOI 10.1007/BF00238594, pages 345–348
^Armitage, A. M. 2000. Armitage's garden perennials a color encyclopedia. Portland, Oregon: Timber Press. Pages 19–20.
^J Ethnopharmacol. 1981 Nov;4(3):247-336. Arrow poisons in China. Part II. Aconitum--botany, chemistry, and pharmacology. Bisset NG.
^"Toxicology in the Old Testament: Did the High Priest Alcimus Die of Acute Aconitine Poisoning?" Authors: Moog F.P.1; Karenberg A.1 Source: Adverse Drug Reactions & Toxicological Reviews (now known as Toxicological Reviews), Volume 21, Number 3, 2002, pp. 151–156(6) Publisher: Adis International
^Roberts, M. F., and Michael Wink. 1998. Alkaloids biochemistry, ecology, and medicinal applications. New York: Plenum Press. Page 18.
