Constituents of the leaves of Helinus ovatus / by John Augustus Goodson.

  • Goodson, John Augustus.
Date:
1920.]
Catalogue details

Licence: Public Domain Mark

Credit: Constituents of the leaves of Helinus ovatus / by John Augustus Goodson. Source: Wellcome Collection.

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    Examination of the Alcoholic Extract. The bulk of the alcohol was removed, and the resulting syrup set aside for some days, when it deposited a considerable quantity of potassium chloride. The filtrate was poured into about four times its volume of water, and treated successively with lead acetate and basic lead acetate. The lead was removed from the two pre¬ cipitates and from the filtrate by hydrogen sulphide in the usual manner. Isolation of Quercetin. The aqueous solution of the material recovered from the lead acetate precipitate contained a considerable amount of tannin. Extraction with ether removed a small quantity of a yellow sub¬ stance, probably quercetin (see below). The liquor was then acidified with hydrochloric acid, boiled to hydrolyse glucosides, cooled, and again extracted with ether, the extract yielding a yellow substance crystallising in rosettes of needles. This was recrystallised from a mixture of alcohol and chloroform, and then melted at 309°. On acetylation, it formed matted, colourless needles melting at 195°, and this melting point was not depressed when the substance was mixed with penta-acetylquercetin. The yellow colouring matter is therefore quercetin. The aqueous solution of the material recovered from the basic lead acetate precipitate also contained tannin, and a small amount of yellow colouring matter, which could not be obtained in a crystalline condition. The fdtrate, after removal of the lead as sulphide, was concen¬ trated and extracted with butyl alcohol, which removed a saponin. The latter was purified by solution in water and precipitation with basic lead acetate, the lead precipitate being decomposed with hydrogen sulphide in the usual manner, and the filtrate evaporated to dryness under diminished pressure. The quantity of saponin obtained was so small that no further .purification could be effected. The material frothed strongly in aqueous solution, gave no com¬ pound with cholesterol in alcoholic solution, did not reduce Eehling’s solution, and was not haemolytic. It was hydrolysed by boiling with dilute hydrochloric acid, the resulting solution yield¬ ing a small amount of apparently crystalline sapogenin on extrac- . tion with ether. The residual aqueous solution reduced Eehling's solution strongly, but did not give a crystalline phenylosazone. The aqueous liquid, after extraction with butyl alcohol, was con¬ centrated under diminished pressure and set aside, when a further