Related entry: Quassia Wood
Quassin may be obtained by exhausting Jamaica quassia wood with 50 per cent. alcohol, neutralising with magnesia, making the solution acid with tartaric acid, and removing the alcohol by distillation. The residue is shaken with chloroform, the solution evaporated to a syrupy consistence and dissolved in a mixture of equal volumes of absolute alcohol and ether; and again evaporated, and dissolved in a little absolute alcohol. This concentrated alcoholic solution is covered with a layer of ether and set aside to crystallise. The product may be recrystallised from alcohol. It is mainly a mixture of two homologous crystalline bitter principles, α-picrasmin, which melts at 204°, and β-picrasmin, which melts at from 209° to 212°. The bitter principle of Surinam quassia, Quassia amara, Linn. (N.O. Simarubeae), is closely allied to, but not identical with, the quassin of Picraena excelsa; like the latter, it is a mixture of homologous, crystalline, bitter principles, and yields quassic acid on hydrolysis with hydrochloric acid. A purified extract in the form of an amorphous, granular, sticky powder, yellowish-brown in colour, is also known commercially as quassin. Quassin occurs in the form of white, odourless, crystalline needles or prisms, which have an extremely and persistently bitter taste, and are neutral in reaction, dextrorotatory, and permanent in air. It yields picrasmic acid on hydrolysis with hydrochloric acid. It is removed from acid solutions by chloroform or benzene. It is not precipitated by lead acetate, but the basic acetate gives a slight cloud. Tannic acid precipitates the quassin from an alcoholic solution.
Soluble in water (about 1 in 1200), easily soluble in alcohol, soluble in chloroform (about 1 in 2), and in benzene, slightly soluble in ether or petroleum ether, soluble in caustic alkalies, and in acid liquids.
Action and Uses.—Quassin is seldom employed in medicine; it is not very suitable for use in aqueous solution, which is the best form in which to administer bitters. It has been given in pill form by trituration with milk sugar and massing with syrup of glucose.
Dose.—2 to 4 milligrams (1/30 to 1/15 grain).