| C33H43NO12 Aconitia. | + H2O Water. | = C7H6O2 Benzoic acid. | + C26H39NO11 Aconine. |
Pseudaconitia, so treated, yields dimethyl-protocatechuic (or “veratric”) acid and a new base, pseudaconine, C27 H41 NO9, the equation being:—
| C36H49O12 Pseudaconitia. | + H2O Water. | = C9H10O4 Dimethyl-protocatechuic acid. | + C27H41NO9 Pseudaconine. |
Aconine is doubtless identical with Hübschmann’s “napel-line,” discovered by him in commercial aconitia, and afterwards proved to be the same as the “acolyctine” which he had previously obtained. Pseudaconine is apparently the base “lycoctonine” of the same chemist.
Commercial aconitia is a mixture of aconitia and pseudaconitia with variable quantities of their decomposition-products, aconine and pseudaconine, and of the amorphous unnamed alkaloids above referred to (Wright and others; Year-Book of Pharmacy, 1877, et seq.). In commercial aconitia prepared from Aconitum napellus (German aconitia), aconitia predominates: English aconitia is chiefly if not entirely prepared from A. ferox, and in it pseudaconitia is the prevailing active base.
All parts of the plants (A. napellus and A. ferox) are poisonous, the active principles being contained in the seeds, roots, leaves and flowering tops. The roots are chiefly used for the extraction of the alkaloids, of which the proportions yielded are very variable and depend on the time when the roots are collected. An ounce of the fresh root of A. napellus contains, according to Woodman and Tidy, from ¼ to ¾ of a grain of aconitia, while a pound of the dried root furnishes from 12 to 36 grains, or 0·1 to 0·2 per cent. “The average produce of the root, collected after flowering and fresh, is 8·58 grains of aconitia in the pound; of the same dried, 35·72 grains. But if collected before flowering, the yield is only 3·5 grains per pound in the fresh, and 12·13 in the dried root (Herapath). These results are the average of several experiments.... The root of A. ferox contains about three times as much alkaloid as that of the English plant” (Royle’s Mat. Med.). According to Wright and Rennie (Year-Book of Pharm., 1880, 458), the percentage of total bases yielded by the root of A. napellus, calculated on the dry substance, amounted to ·07 per cent., equivalent to about ·05 per cent, of total alkaloids in the dry herb. Two-fifths of the total alkaloid consisted of pure crystallized aconitia.
Commercial aconitia or aconitine is generally met with as a white amorphous powder, but is occasionally crystalline. It dissolves in 150 parts of cold and 50 parts of hot water, and is also soluble in alcohol, benzole, and chloroform: it is inodorous, possesses an acrid taste (W. and T., For. Med., p. 392), and is strongly alkaline to test-paper. It generally fuses below 100° C. (60° C., W. and T.), and gives an amorphous sublimate above 150° C. (pure aconitia fuses at 183°-184° C.: pure pseudaconitia melts at 104°-105° C.): when strongly heated with free access of air, it burns with a yellow, smoky flame, leaving no residue. Crystallized samples of commercial aconitia are the purest. Amorphous aconitia, and particularly that prepared in Germany, is very impure, being admixed with considerable quantities of comparatively inert bases. The use of such a preparation should be avoided, as being liable to give rise to a false idea as to the proper dose of the pure alkaloid (Royle’s Mat. Med., 1876, p. 773). Morson’s “English aconitine” (pseudaconitia) is much more powerful than the French and German products, which are mostly prepared from A. napellus, and consist mainly of aconitia.[221]
Aconitia and pseudaconitia differ from one another in their molecular weights and melting-points; they also furnish different decomposition-products: aconitia readily furnishes well-crystallized salts, while the salts of pseudaconitia are usually obtained amorphous; and finally, crystallized aconitia is anhydrous, while pseudaconitia crystallizes with one atom of water.
The two bases are similar as regards their physiological action (pseudaconitia is perhaps somewhat more powerfully active than aconitia), and general behaviour with reagents.