The Active Principle of Polygonum Hydropiper.
By C. J. RADEMAKER, M.D.
Having seen hydropiper frequently used, both in the form of tincture and fluid extract in amenorrhoea and other uterine disorders, with very satisfactory results, I was induced to make a chemical examination of this drug.
In order to obtain the active principle or principles the following processes were resorted to:
Experiment 1st.—Two pounds of the herb were exhausted with diluted alcohol, the alcohol distilled off by means of a water-bath, the remaining liquid was evaporated to about one-third of the original bulk; during the evaporation a considerable amount of resinous matter was precipitated, the solution was filtered from the resinous precipitate and the filtrate treated with basic acetate of lead, which produced a yellow precipitate.
The precipitate produced was collected on a filter and washed with distilled water. The precipitated magma was then suspended in distilled water and treated with sulphuretted hydrogen; the resulting mixture of sulphide of lead and organic principle was treated with ether, the ether separated from the sulphide of lead and allowed to evaporate spontaneously.
The crystals thus formed were soluble in alcohol, ether, chloroform, and slightly soluble in diluted alcohol, but almost insoluble in water; when rubbed with water they become very sticky; the solution of the crystals had an acid re-action with litmus. Under the microscope they made a beautiful appearance, resembling the crystals of uric acid of human urine.
This acid may be called polygonic acid.
Experiment 2d.—The filtrate from which the acid had been removed by means of basic acetate of lead, was treated with sulphuric acid, in order to remove the excess of lead, and then rendered alkaline by means of caustic potash and treated with ether.
The ether was separated and allowed to evaporate spontaneously. The mass thus left was perfectly white, neutral to test-paper, and had a bitter taste, was soluble in alcohol, ether, and the mineral acids; its solution in acids was not precipitated by ammonia, caustic potash, or sodic carbonate, nor was I able to obtain any crystals. From this I concluded that it possessed no basic properties.
Experiment 3d.—One pound of fluid extract (480 grs. to the fluidounce) was treated with hydrochloric acid, about five drops of the acid to each fluid-ounce of the liquids, and then treated with ether. The ether separated and treated with basic acetate of lead, the precipitate produced was collected on a filter and washed with distilled water, the precipitated magma was suspended in distilled water and treated with sulphuretted hydrogen.
The mixture of sulphide of lead and organic principle was again treated with ether, the ether separated from the sulphide of lead, evaporated and the acid crystallized.
The crystals produced resembled those as prepared in experiment No. 1.
Chemical properties of Polygonic Acid. Polygonic acid, as prepared in experiments 1 and 3, has a green color, acrid, and bitter taste. It has strong acid properties, completely neutralizing bases, and uniting with them to form salts.
Aqua ammoniae, caustic potash and sodic carbonate, added to the crystals or a solution of the crystals, produced an intense yellow color, and the crystals were dissolved. Nitric and hydrochloric acids added to crystals or solution of the acid produced a yellow color. Sulphuric acid added to the crystals or a solution of polygonic acid, produced a dark red color, which gradually became black. Basic acetate of lead added to a solution of the acid or its salts, produced a yellow precipitate, soluble in the mineral acids. Nitrate of suboxide of mercury produced a yellowish white precipitate, soluble in the mineral acids. Mercuric chloride produced a green precipitate, soluble in the mineral acids. Cyanide of potassium produced a yellow color. Ferric chloride produced a slight dark color. Cupric sulphate produced a slight green color. Baric chloride, chloride of gold, nitrate of silver and chloride of platinum produced no change.
From the above it will be seen that polygonum hydropiper contains an acid, crystallizable, coloring principle upon which the medicinal virtues of the drug mainly depend.