The first to be mentioned is Aconitine, a highly active crystallizable alkaloid, furnishing readily crystallizable salts. It is accompanied by another active alkaloid, Pseudaconitine, which is crystallizable, but yields mostly amorphous salts. According to the admirable researches of Wright and Luff,[39] aconitine may be decomposed according to the following equation:—
| C₃₃H₄₃NO₁₂ | · OH₂ = | C₇H₆O₂ | · C₂₆H₃₉NO₁₁, |
| Aconitine. | Benzoic acid. | Aconine. |
and pseudaconitine breaks up in accordance with the equation:
| C₃₆H₄₉NO₁₁ | · OH₂ = | C₉H₁₀O₄ | · C₂₇H₄₁NO₈ |
| Pseudaconitine. | Dimethyl- protocatechnic acid. | Pseudaconine. |
The decomposition of aconitine, as well as of pseudaconitine, may be performed by means of mineral acids, alkaline solutions, or also by heating the bases with water in sealed tubes. The two alkaloids, Aconine and Pseudaconine, appear to be present already in the roots of Aconitum; they, moreover, contain two other alkaloids of less physiological potency. One of them, Picraconitine, C₃₁H₄₅NO₁₀, is merely bitter, producing no lip-tingling; it gives well crystallized salts, although it is itself amorphous. Commercial aconitine is a mixture of the above alkaloids. The total yield of basic substances afforded by aconite root is not more than about 0·07 per cent.
The other constituents of aconite root are but imperfectly known. In the preparation of the alkaloids, a dark green mixture of resin and fat is obtained; it is much more abundant in European than in Nepal aconite (Groves). The root contains Mannite, as proved by T. and H. Smith (1850), together with cane-sugar, and another sugar which reduces cupric oxide even in the cold. Tannin is absent, or is limited to the corky coat. The absence of a volatile alkaloid in the root was proved by Groves in 1866.
Uses—Prescribed in the form of tincture as an anodyne liniment; occasionally given internally in rheumatism.
Adulteration and Substitution—Aconite root, though offered in abundance in the market, is by no means always obtained of good quality. Collected in the mountainous parts of Europe by peasants occupied in the pasturing of sheep and cattle, it is often dug up without due regard to the proper season or even to the proper species,—a carelessness not surprising when regard is had to the miserable price which the drug realizes in the market.[40]
One of the species not unfrequent in the Alps, of which the roots are doubtless sometimes collected, is A. Störckeanum Reichenb. In this plant the tuberous roots are developed to the number of three or four, and have an anatomical structure slightly different from that of A. Napellus.[41] A. variegatum L., A. Cammarum Jacq., and A. paniculatum Lam. are blue-flowered species having tuberous roots resembling those of A. Napellus, but according to Schroff somewhat less active.
The yellow-flowered A. Anthora L. and A. Lycoctonum L. produce roots which cannot be confounded with those of A. Napellus L.