CHAPTER XI.
ACONITE: ACONITIA OR ACONITINE.
Plants: Aconitum napellus—A. ferox. Alkaloids: Aconitia—Pseudaconitia—other bases—Decompositions—Proportions in the plants. Commercial aconitia—German aconitia—English aconitia. Separation—Tests, chemical and physiological. History—Preparations, official and non-official. Physiological effects—Causes of death—Post mortem appearances—Treatment and antidotes—Remarks—Phosphoric acid test—Case referred to by Dr. Stevenson.
The name aconite is applied to a great number of plants belonging to the natural order Ranunculaceæ. Two species only need be noticed here, Aconitum napellus and A. ferox. The former is the well-known “monkshood,” “wolfsbane,” or “blue rocket,” a very beautiful but exceedingly poisonous plant, commonly cultivated in English gardens. This very variable and widely diffused species is found in the mountainous districts of the temperate regions of the northern hemisphere: it occurs in the Alps up to an altitude of more than 6,000 feet, in the Pyrenees, and in the mountain ranges of Germany and Austria. It is also met with in Sweden, Denmark, Siberia, and in the mountainous districts on the Pacific coast of North America.
Aconitum ferox, Nepaul aconite —“Bikh”), is a native of the subalpine Himalayas, occurring, together with A. napellus and several other poisonous species, at an elevation of 10,000 to 14,000 feet.
The most recent researches of Dr. C. R. Alder Wright and others have shown that Aconitum napellus chiefly owes its poisonous properties to the base aconitia, or aconitine (also called aconitina), C33 H43 NO12, a highly active crystallizable alkaloid furnishing readily crystallizable salts. This base constitutes about one-half of the total quantity of alkaloids present in the root, and is considered to be in combination with aconitic acid, H3 C6 H3 O6. There is also present, but in much smaller quantity (about 10 per cent. of the total bases present—Wright), another physiologically active crystallizable alkaloid, pseudaconitia, C36 H49 NO12, similar in many respects to aconitia (especially in its effects upon the animal system), but not so readily yielding crystallizable salts. The roots of A. napellus contain, in addition to aconitia and pseudaconitia, a considerable quantity of a third base, comparatively inert, apparently amorphous, yielding non-crystallizable salts, and containing a higher percentage of carbon than either aconitia or pseudaconitia.
Aconitum ferox contains as its active principle pseudaconitia, or nepaline, associated with a comparatively small quantity of aconitia: there is present in addition a non-crystallizable alkaloid containing more carbon than either of the other bases, but apparently not identical with the analogous body from A. napellus.
The plants have been stated to contain, besides the bases already named, various other alkaloids, such as “napel-line,” “acolyctine,” “lycoctonine,” &c., but there is no doubt that these substances are merely products of the decomposition of aconitia and pseudaconitia, formed during the process of extraction. Aconitia and pseudaconitia are very easily decomposed; thus, when heated with water in a sealed tube, the former is converted into benzoic acid and a fresh alkaloid, aconine, C26 H39 NO11, the reaction being represented by the following equation:—