The Root of Phytolacca Decandra, Linne.
BY EDMOND PRESTON, JR., PH.G.
From an Inaugural Essay.
No plant among us is more conspicuous in the fall than the poke for its large clusters of annual purple stems, covered, at the top with ovate-oblong leaves, and bearing large pedunculated racemes of fine purple colored berries. A peculiar phenomenon was noted while observing Phytolacca at night in the fall, the leaves presenting a phosphorescent appearance in the dark. This peculiarity not being mentioned in any of the Dispensatories, a further search was made for a record of such a phenomenon in connection with this plant, and the following was found in Gmelin's Chemistry, vol. i, p. 188:
"Some plants emit in the dark a faint, continuous light, probably resulting from the formation of some substance which burns and emits light at ordinary temperatures, and consists, not of phosphorus, but more probably of a compound containing carbon and hydrogen. The leaves of Phytolacca decandra have been observed to shine in September from 9 till 12 o'clock at night, sometimes with blueish-green, sometimes with yellowish-green light, accordingly as the current of air was stronger or weaker; they also remained luminous after being wiped."
The large perennial root, in some specimens from 8 to 10 inches in diameter, has an expanded crown where the numerous stems are joined, This thick part of the root grows perpendicularly to the depth of 12 to 18 inches, where it divides into from two to four nearly equal branches, which extend horizontally, in different directions, from 6 to 10 feet, from the main root, and gradually taper in size. These main branches seldom divide again, but irregularly send off smaller ones.
Estimation of Moisture.—100 gm. of the fresh root, sliced in thin pieces, was allowed to dry in the air to the condition as it is found in commerce, losing thereby 72.84 gm. On continued exposure in a drying chamber until it ceased to lose weight a loss of 7.889 gm. was noted, showing a total of 80.729 per cent. of moisture and 29.046 per cent. In the air-dried or commercial root.
Ash,—10 gm. of the powdered (air-dry ?) root yielded an ash weighing .84 gm., equal to 8.4 per cent. Of this ash .68 gm. was soluble in water, .16 gm. insoluble. Potassium was found to be the principal base in the soluble portion, by precipitating it with saturated solution of bitartarate of sodium; it equals nearly 5.5 per cent. KOH of the powdered root. The large amount of potassium salts found in this drug is noticeable. A little sulphuric and hydrochloric acid, besides carbonate, was found in this portion. The ash insoluble in water yielded to hydrochloric acid a little calcium and iron, and left silica behind.
In the following experiments the fresh root was used. The experiments of Donnelly ("Am. Jour. Phar." Oct., 1843, p. 165) and W. F. Pape (Ibid., Dec., 1881, p. 597) were verified in so far as to the finding of starch, tannin, gum, sugar, resin, fixed oil and lignin. In view of the rapid deterioration of Phytolacca root on keeping, and the probability of its containing an alkaloid, as pointed out by W. F. Pape, the first experiments made were in search of a volatile alkaloid.
A strong tincture of the root, prepared with diluted alcohol, and made alkaline with solution of potassa, was distilled in a glass retort, and the distillate, having a strong, disagreeable odor of the root, was caught in distilled water slightly acidulated with sulphuric acid. After concentration, the tests for alkaloids were applied, with negative results.
A portion of the root was finely broken up and macerated in cold water for 24 hours, then , the whole introduced into a retort and distilled in a salt water bath. The distillate had the characteristic odor and acrid taste of the root, and a strong acid reaction. The acid distillate was set aside and the contents of the retort divided into three portions. With the first distillation was continued as before, but no change took place in the distillate. The second and third portions were distilled separately after the addition of solution of potassa and sulphuric acid to each respectively, and still no change could be noted in the distillate.
The first acid distillate was then carefully neutralized with solution of potassa. A change of color was here noted as the liquid neared neutrality, the colorless liquid changing to a pale light yellowish-green, and at the same time the odor almost entirely disappeared. The solution was slowly and carefully evaporated to a small bulk, and, on allowing to stand, a small crop of nearly colorless acicular crystals separated. These had an acrid taste, resembling that of the root, after remaining in the mouth a short time. On being treated with acids the salt was decomposed, the acid going off with effervescence, and giving the characteristic strong disagreeable odor of the root in an intensified degree. The crystals I consider to be the potassium salt of a volatile acid characteristic of Phytolacca root.
A strong decoction of the root was precipitated with solution of sub-acetate of lead, filtered, and the lead precipitated from the filtrate by a current of hydrosulphuric acid gas; again filtered, and a portion evaporated to a small bulk. This was divided into four parts, and tested for alkaloids with phosphoric lybdic acid, tannin, iodohydrargyrate of potassium and auric chloride; each gave a precipitate indicating the presence of an alkaloid, to separate which the following method was used:
The filtrate from the lead precipitate was carefully concentrated and mixed with an equal volume of saturated alum solution. The mixture was heated, ammonia added in slight excess, the whole evaporated on a water-bath, and the residue powdered and extracted with alcohol. On evaporating the alcoholic liquid a yellowish mass of small crystals was obtained. This was redissolved in alcohol, the solution passed through animal charcoal and carefully evaporated, when small, nearly white crystals were left. These were quite soluble in alcohol, moderately so in water and nearly insoluble in ether and chloroform. They were entirely dissipated when heated upon platinum foil, and in aqueous solution gave precipitates with the four alkaloidal reagents before mentioned. With strong nitric, sulphuric or hydrochloric acids the crystals simply dissolved, giving no characteristic color test.
The alcoholic solution of the crystals, neutralized with diluted hydrochloric acid, on concentration yielded nearly colorless acicular crystals, which were moderately soluble in alcohol, quite soluble in water, and possessed a strong acrid taste.
From these results I conclude that the crystals were those of an alkaloid contained in Phytolacca root and of the hydrochlorate of the same, for which I propose the name of Phytolaccine.
The American Journal of Pharmacy, Vol. 56, 1884, was edited by John M. Maisch.