The nature and origin of the poison of Lotus Arabicus / by Wyndham R. Dunstan and T.A. Henry.

  • Dunstan, Wyndham R. (Wyndham Rowland), 1861-1949.
Date:
1901
Catalogue details

Licence: In copyright

Credit: The nature and origin of the poison of Lotus Arabicus / by Wyndham R. Dunstan and T.A. Henry. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    of either alcohol or boiling water, recalls the very similar behaviour of the seed of the hitter almond tree (Primus amygdalus, var. amara), which, as is well known, contains ■a glucoside amygdalin and an enzyme emulsin, the interaction of which in the presence of cold water results in the hydrolysis of the amygdalin, with the formation of hydro- cyanic acid, dextrose, and benzaldehyde. The similarity in the behaviour of Lotus arabicus and bitter almonds was highly suggestive of the existence of substances in the former similar to amygdalin and emulsin. This suggestion received further support in the observation that when the dried alcoholic extract of Lotus was warmed with dilute hydrochloric acid, hydrocyanic acid was produced, together with a sugar capable of reducing Fehling’s solution. Extraction of the Glucoside. The dried plant reduced to a fine powder was extracted in the cold with purified methylated alcohol. The mixed alcoholic liquors were then concentrated to a syrup, which was boiled repeatedly with water in order to separate the glucoside from the chlorophyll and resin. Tannin, gum, and similar substances were removed by pre- cipitation with lead acetate in the usual manner. The purified aqueous solution, ■after removal of excess of lead, was bright yellow in colour. It was evaporated on the water-bath until of a syrupy consistence, when it was exposed in a vacuous desiccator over quicklime, and as all other methods failed to induce anything to crystallise, it was left in the desiccator and well stirred every day. After some weeks a small quantity of a substance crystallising in minute yellow needles separated. This was removed from the viscid mother liquor by absorption of the latter in a porous tile, which was then broken up and extracted with water. This extract evidently still contained far more of the substance than could he readily separated in a crystalline condition. From nearly a kilogramme of the plant only about '25 gramme of crystalline material was extracted, but by working up about 10 kilogrammes of the plant a quantity sufficient for analysis was eventually obtained. The substance thus prepared proved to be a glucoside, which it is proposed to name lotusin. It was re-crystallised from hot alcohol, and was thus obtained in needles having a very faint yellow colour. It is bitter to the taste, and does not reduce Fehling’s solution except after long boiling. It has no definite melting point, but decomposes when slowly heated. Unlike quercitrin and other similar glucosides of colouring matters, lotusin is not precipitated by lead acetate, a fact which we have utilised in purifying it. With the exception of amygdalin, lotusin is the only glucoside definitely known which furnishes prussic acid as a decomposition product. Combustions of specially purified material, dried at 100° C. until of constant weight, gave the following results :—