II.—Other Poisonous Glucosides Acting on the Heart.
§ 548. Several members of these glucosides have been studied by Schmiedeberg,[582] and his convenient divisions will be followed here:—
[582] Beiträge zur Kentniss der pharmakol. Gruppe des Digitalins.
1. CRYSTALLISABLE GLUCOSIDES.
Antiarin (C14H20O5).—Antiarin is an arrow poison obtained from the milky juice of the Antiaris toxicaria growing in Java. Antiarin is obtained in crystals, by first treating the inspissated milky juice with petroleum ether to remove fatty and other matters, and then dissolving the active principle out with absolute alcohol. The alcoholic extract is taken up with water, precipitated with lead acetate, filtered, and from the filtrate antiarin obtained by freeing the solution from lead, and then evaporating. De Vry and Ludwig obtained about 4 per cent. from the juice. Antiarin is crystalline, the crystals containing 2 atoms of water. Its melting-point is given as 220·6°; the crystals are soluble in water (254 parts cold, 27·4 parts boiling), they are not soluble in benzene, and with difficulty in ether; 1 part of antiarin requiring 2792 parts of ether.
The watery solution is not precipitated by metallic salts. On warming with dilute mineral acids, antiarin splits up into a resin and sugar. Concentrated sulphuric acid gives with antiarin a yellow-brown solution, hydrochloric and nitric acids strike no distinctive colours.
§ 549. Effects.—Antiarin is essentially a muscular and a heart poison. When given in a sufficient dose, it kills a frog in from half an hour to an hour. Its most marked effect is on the cardiac muscle, the heart beats more and more slowly, and at last stops, the ventricle being firmly contracted. As with digitalin, there is a very marked prolongation of the systole, and as with digitalin, after the beats have ceased, a forcible dilatation of the ventricle will restore them (Schmiedeberg). It is doubtful whether by physiological experiment antiarin could be differentiated from digitalin.
§ 550. Separation of Antiarin.—In any case of poisoning by antiarin, it would be best to extract with alcohol, evaporate, dissolve the alcoholic extract in water, precipitate with lead acetate, filter, free the filtrate from lead, and then, after alkalising with ammonia, shake the filtrate successively with petroleum ether, benzene, and a small quantity of ether in the manner recommended at [page 247], et seq. The liquid, now freed from all fatty, resinous, and alkaloidal bodies, is neutralised and evaporated to dryness in a vacuum, and the dry residue taken up with absolute alcohol, filtered, the alcohol evaporated at a very low temperature, and finally the extract dissolved in a small quantity of water, and submitted to physiological tests.