Cinchonidine (thus called by Pasteur in 1853) was first obtained and characterized under the name of Quinidine in 1847, by F. L. Winckler of Darmstadt, from Maracaibo Bark (C. tucujensis Karst.); and in 1852 it was more closely studied by Leers, still under the name of quinidine.
Cinchovatine, formerly stated to be a peculiar alkaloid, has been shown by Hesse in 1876 to agree with cinchonidine.
Quinidine is the name applied by Henry and Delondre to an alkaloid they obtained in 1833; its peculiar nature was not clearly proved until 1853, when Pasteur examined it, and 1857 when De Vry showed its identity with the Beta-quinine extracted in 1849 by Van Heijningnen from commercial quinoidin. The name quinidine having been since applied to different basic substances more or less pure, Hesse (1865) has proposed to replace it by that of Conquinine (Conchinin in German). The alkaloid is especially characteristic of the Pitayo barks, and also occurs in the Calisaya barks from Java.
Quinamine was discovered in 1872 by Hesse, in bark of C. succirubra cultivated at Darjiling in British Sikkim; it is also of common occurrence in the barks collected in Java. Conquinamine was extracted in 1873 by Hesse from old barks from British India.
Paricine is another basic substance discovered in 1845 by Winckler, in the bark of Buena hexandra Pohl. Hesse detected it along with quinamine in the bark of C. succirubra; its composition is not yet known.
Aricine, C₂₃H₂₆N₂O₄, and Cusconine, C₂₃H₂₆N₂O₄ + 2 OH₂, occur in the so-called false Cinchona barks of not ascertained botanic origin. These alkaloids differ in many respects from those of true Cinchona barks.[1355]
Pitoyine was pointed out by Peretti (1837), but Hesse has shown (1873) that the bark called China bicolorata Tecamez[1356] or Pitoya Bark from which it was obtained, is altogether destitute of alkaloid.
Lastly may be mentioned Paytine, C₂₁H₂₄N₂O + OH₂, a crystallizable alkaloid discovered in 1870 by Hesse in a white bark of uncertain origin.[1357] It is allied to quinamine and quinidine, but has not been met with in any known cinchona bark.
By heating for a length of time solutions of the cinchona alkaloids with an excess of some mineral acid, Pasteur (1753) obtained amorphous modifications of the natural bases. Quinine thus afforded Quinicine, having the same composition; cinchonine and cinchonidine furnished Cinchonicine, likewise agreeing in composition with the alkaloids from which it originates. These amorphous products may also be obtained by heating the natural bases in glycerin at 200° C., when a red substance is also formed. In quinine manufactories, amorphous alkaloids are constantly met with, being partly produced in the course of the manipulations to which the materials are subjected. Yet cinchona barks also afford amorphous alkaloids at the very outset of analysis, whence we must infer their existence in the living plant.
The name Quinoidine (or rather “Chinioïdin”) was applied by Sertürner (1829) to an uncrystallizable basic substance, which he prepared from cinchona barks, and found to be a peculiar alkaloid. The term has subsequently been bestowed upon a preparation which has found its way into commerce and medical practice, in the form of a dark brown brittle extractiform mass, softening below 100° C., and having usually a slight alkaline reaction. It is obtained in quinine factories by precipitating the brown mother-liquors with ammonia, and contains the amorphous alkaloids naturally occurring in the barks. Quinoidin should not be used unless, when previously dried at 100°, it proves to afford at least 70 per cent. of alkaloids soluble in ether.