Chemical Composition—The active principle of colchicum seed is termed Colchicin, but the chemists who have made it the subject of investigation are not agreed as to its properties. Thus Oberlin (1856) showed it to contain nitrogen, but without possessing basic properties. By treatment with acids, the amorphous colchicin yields a crystallizable body, Colchiceïn. Hübler (1864) prepared colchicin in the same way by which the so-called “bitter principles,” like dulcamarin ([p. 451]) are obtainable. He assigned to colchiceïn acid qualities and, strangely enough, the same formula he gave for colchicin itself, namely C₁₇H₁₉NO₅. Maisch[2622] as well as Diehl[2623] again obtained discrepant results. Colchicin of definite composition has not yet been isolated.
It would appear that in an aqueous or alcoholic extract of the seed an extremely small amount of an alkaloid is present, but that a basic substance is immediately formed on addition of mineral acids, or also oxalic acid. This suggestion is to some extent supported by the following facts:—
By adding the usual test solution for alkaloids, i.e. iodohydrogyrate of potassium (50 grammes of iodide of potassium, 13·5 of perchloride of mercury in one litre), to an aqueous solution of an alcoholic extract of the seeds, a very slight turbidity, or an insignificant precipitate is observed. Yet on addition of sulphuric, or nitric, or hydrochloric acid, an abundant precipitate of a beautiful yellow is at once produced. This experiment succeeds with a few seeds, either entire or powdered; it may be conveniently applied for the detection of colchicum in any preparation. We have ascertained that the yellow precipitate can be obtained also with the other parts of the plant. If the yellow compound is decomposed by sulphuretted hydrogen, the filtrate, after due concentration, now precipitates immediately on addition of the iodohydrogyrate, yet still more abundantly in presence of a mineral acid.
The seeds contain traces of gallic acid, much sugar and fatty oil. Of the last we obtained 6·6 per cent. by exhausting the dried seed with ether. The oil concreted at -8° C. Rosenwasser (1877) obtained 8·4 per cent. of the oil.
Uses—The same as those of the corm.
SMILACEÆ.
RADIX SARSAPARILLÆ.
Radix Sarzæ vel Sarsæ; Sarsaparilla; F. Racine de Salsepareille; G. Sarsaparillwurzel.
Botanical Origin—Sarsaparilla is afforded by several plants of the genus Smilax, indigenous to the northern half of South America, and the whole of Central America as far as the southern and western coast-lands of Mexico.
These plants are woody climbers, often ascending lofty trees by the strong tendrils which spring from the petiole of the leaf. Their stems are usually angular, armed with stout prickles, and thrown up from a large woody rhizome. The medicinal species inhabit swampy tropical forests, which are extremely deleterious to the health of Europeans, and can only be explored amid great difficulties. This circumstance taken in connexion with the facts that the plants are diœcious, that their scandent habit often renders their flowers and fruits (produced at different seasons) inaccessible, and that their leaves vary exceedingly in form,[2624] explains why we are but very imperfectly acquainted with the botanical sources of sarsaparilla.