Picrotoxinum, B.P. Picrotoxin.
Related entry: Levant berries
C45H50O19 = 894.4.
Picrotoxin, or Cocculin, C45H50O19, a neutral principle obtained from the fruit of Anamirta paniculata, Colebrooke (N.O. Menispermaceae), may be prepared by exhausting the powdered Cocculus Indicus with boiling alcohol, concentrating the liquid by distillation, and evaporating to a low bulk; on cooling, the fat is removed, and the residue boiled with water; the aqueous solution is filtered while hot, the filtrate made slightly acid and crystallised. The crystals are purified by dissolving in hot strong alcohol, adding animal charcoal, filtering while hot, and recrystallising. Picrotoxin occurs in the form of intensely bitter, poisonous, colourless, odourless, shining, prismatic crystals, or as a micro-crystalline powder. It is permanent in the air. The alcoholic solution is laevorotatory. Its solution in acids and alkalies is not attended by formation of salts, but it is precipitated from alkaline solutions by carbon dioxide. Amyl alcohol, benzene, and chloroform extract the principle from acid, but not from alkaline solutions. Melting-point, 193° to 200°; repeated crystallisation, however, ensures a melting-point of from 199° to 200°. The crystals melt on heating, forming a yellow liquid, which chars on further heating, and on ignition is entirely consumed without leaving any residue. It dissolves in sulphuric acid with a saffron-yellow colouration, passing to a red violet on the addition of potassium bichromate. A trace of picrotoxin treated with a 20 per cent. solution of benzaldehyde in alcohol, and a drop of sulphuric acid added, produces a red colour which, on gently stirring, forms red streaks throughout the liquid. If a mixture of picrotoxin and three times its weight of potassium nitrate be moistened with strong sulphuric acid, and a strong solution of sodium hydroxide be added, an intense red colour will be developed. By bromination, or by the action of hydrochloric acid on its ethereal solution, it is readily decomposed into picrotoxinin and picrotin.
Soluble in water (1 in 334), boiling water (1 in 35), alcohol (1 in 13.5), boiling alcohol (1 in 3), solution of potassium hydroxide (1 in to), in amyl alcohol, benzene, ether, chloroform, or glacial acetic acid.
Action and Uses.—Picrotoxin is a powerful convulsive poison, differing from strychnine in that it acts mainly on the medulla. It is used principally to check the profuse night-sweats of phthisis, through its action in accelerating respiration, thus removing the partial asphyxia and so preventing stimulation of the nervous mechanism governing perspiration; but it is successful only in a certain proportion of cases. Picrotoxin was at one time used to adulterate beer, giving it a fictitious reputation as an intoxicant. It is best administered in pills, the drug being triturated with milk sugar and the mass prepared with glycerin of tragacanth. A solution in water (1 in 400) is used by hypodermic injection. It has been used as an antidote in morphine poisoning; also in the form of ointment (1 in 50) as a parasiticide, but it is too dangerous a substance for use in this way. In cases of poisoning by picrotoxin, the stomach should be washed out, and chloral hydrate and potassium bromide given.
Dose.—½ to 2 ½ milligrams (1/100 to 1/25 grain).