Chemical examination of cascara bark / by H.A.D Jowett.

  • Jowett, H. A. D. (Hooper Albert Dickinson)
Date:
[1904?]
Catalogue details

Licence: In copyright

Credit: Chemical examination of cascara bark / by H.A.D Jowett. Source: Wellcome Collection.

    20/28 (page 18)
    with ammonia, and reduced Fehling’s solution. The acid solution became turbid on boiling. As will be shown later, the active constituents of the drug appear to be contained in this extract. The acetone extract gave a very small residue which was similar in all respects to that obtained from the ethyl acetate extract. The alcoholic extract gave a dark red residue, and constituted the greater portion of the subacetate precipitate. It showed no signs of crystallizing, even on long standing, was readily soluble in water, and behaved in most respects like the ethyl acetate residue, except that it only slightly reduced Fehling’s solution. The aqueous extract afforded a very dark colored residue, which gave no coloration with either ferric chloride or ammonia, and only slightly re¬ duced Fehling’s solution. It gave a dirty black precipitate with lead sub¬ acetate, and was not further examined. As no crystals could be obtained, the ethyl acetate and alcoholic residues were separately treated with alcoholic hydrochloric acid in a reflux apparatus, the alcoholic solution poured into excess of water, and the dense, greenish-black precipitate produced in each case examined as follows : 1. Ethyl acetate extract. This precipitate was dried and extracted in a Soxhlet apparatus with petroleum, ether, benzene and alcohol, succes¬ sively, but in no case could any crystals be obtained, even after solution of the respective residues in glacial acetic acid. No trace of emodin, chrysophanic acid, chrysarobin, or other crystalline substance was found. The residues were therefore collected and mixed with those from the alcoholic extract, and the combined residues fused with potassium hydroxide. 2. Alcoholic extract. This was treated in exactly the same way as the ethyl acetate extract, and from the petroleum residue a small amount of a crystalline substance was obtained which gave the emodin color reaction with ammonia. The crude crystals weighed less than 0.05 gramme, and in this case must be considered to have been present in the original ex¬ tract, and not to have been formed by hydrolysis. The other extracts gave no trace of crystalline substance. Fusion with potassium hydroxide. The mixed residues (1 and 2) were fused with five times their weight of potassium hydroxide, and from the products of fusion a small amount of protocatechuic acid (m. p. i93°C.) was isolated. No other definite substance was obtained. The examination of the lead subacetate precipitate showed, therefore, that no crystalline pro¬ duct, or anything corresponding to Dohme and Engelhardt’s purshianin, could be isolated from it, and that no evidence could be obtained of the existence of any glucoside yielding emodin or chrysophanic acid on hydrolysis. 6. The Filtrate from the Lead Subacetate Precipitate. 1 his was freed from lead by hydrogen sulphide in the usual manner,