2.6.2 Quassin
Synonym Nigakilactone D
Biological Sources It is obtained from the wood of Quassia amara L., (Simaroubaceae) commonly known in commerce as Surinam quassia. It is also obtained from the stem wood of Picrasma excelsa (Sw.) Planch. (Aeschrion excelsa or Picroena excelsa) known in commerce as Jamaican quassia. All these species belong to the natural order Simaroubaceae).
Chemical Structure
2, 12-Dimethoxypicrosa-2, 12-diene-1, 11, 16-trione; (C22H28O6).
Isolation The following steps may be adopted in a sequential manner for the isolation of quassin.
1. The quassia wood is chopped into small pieces and subjected to aqueous decoction, which is filtered and concentrated to the original weight of the wood taken; and finally neutrallized carefully with Na2CO3.
2. Tannic acid solution (5% w/v) is added slowly until no more precipitate is obtained.
3. The precipitate thus obtained is filtered, collected and transferred to a pestle and mortar, triturated with solid lead carbonate (or with freshly prepared lead oxide), so as to liberate quassin and form lead tannate; and the resulting mass is dried on a water bath.
4. The dried mass is powdered and then subjected to extraction with 80% (v/v) ethanol successively.
5. The combined ethanolic extract is filtered and concentrated under vacuo and left for cooling overnight, when the crystals of quassin would separate out.
Quassin may also be obtained by the resolution of the mixture of bitter constituents of quassia
wood by the method of London et al.*
Characteristic Features
1. Quassin is obtained as rectangular plates from dilute methanol having mp 222°C.
2. Its specific optical rotation [α]20D + 34.5° (C = 5.0 g in CHCl3).
3. It has uvmax: ~ 255 nm (ε ~ 11,650).
4. It is extremely bitter; and it has the bitterness threshold 1 : 60,000.
5. It is found to be freely soluble in benzene, acetone, ethanol, chloroform, pyridine, acetic acid, hot ethyl acetate; and sparingly soluble in ether and petroleum ether.
Identification Tests
1. Add to a few crystals of quassin 2-3 drops of concentrated, H2SO4 and sucrose when a red colouration is produced.
2. Phloroglucin Test: Dissolve 2-3 mg quassin in 1-2 ml ethanol, and add to it a few crystals of phloroglucin and a few drops of concentrated. HCl, when a crimson red colour is obtained.
Uses
1. It possesses insecticidal properties.
2. The quassia wood extract is used as a bitter tonic.
3. Quassin exhibits anthelmintic properties, and on being administered as enema expels thread worms specifically.
