Cascara Amarga—Honduras Bark.

Botanical name: 

BY F. A. THOMPSON, PH.C., Detroit, Michigan.

Cascara Amarga, also known as Honduras Bark, is obtained from a tree indigenous to Mexico. A description of this tree I am unable to furnish. Specimens of this bark have been submitted to Dr. Vasey of the Department of Agriculture at Washington, for examination, resulting in the opinion that it belonged to the genus Picramnia (from picros, bitter, and thamnos, shrub), which numbers no less than twenty species. Dr. Vasey having only two varieties in his possession he was unable to determine the exact variety. Picramnia is said by different botanists to belong to the natural order Anacardiaceae.

Fig. 1. Cascara amarga. Fig. 2. Cross-section Fig. 3. Transverse section

The bark as seen in commerce, is mostly deprived of its outer bark which is from one to three millimeters thick, of a brownish-gray color, striated, and much divided by numerous longitudinal fissures. After being immersed in water, it assumes a greenish-yellow tint. The inner bark is of a deep-brown color, three or four millimeters thick, hard, and firm, of a bitter taste, and on examination of a transverse section numerous white spots are to be seen, which appear to be filled with a white insoluble inert substance.

Microscopical Examination:—The outer or cork bark (a) is composed of twenty-five or thirty rows of regular thick-walled cells, filled with red coloring matter. The middle bark is composed of large, irregular parenchyma cells (d) making up the greater share of the whole bark. Throughout this portion of the bark are numerous sclerenchyma cells (b) arranged in groups and also one to three rows are always found close to the outer bark. These sclerenchyma cells make a prominent marking, as seen with naked eye, in cross-section fig. 2. Also at intervals, are one to three ranked series of sclerenchymatous fibres or bast-fibres (c) arranged tangentially, which turn brown after treatment with iodine. The inner bark does not differ very much from the middle except it is divided by several rows of medullary rays (e) composed of regular cells.

Chemical Examination:—A portion of drug dried at 110°C until constant weight, was found to lose 10 per cent. as moisture. Another portion was incinerated, leaving a white ash amounting to 4.55 per cent.

Soluble in water: K, Na, sulphate, carbonate1.10
Soluble in dilute hydrochloric acid; Aluminum, iron, phosphates and carbonates2.89
Insoluble in sodium hydrate; sand.56

Several portions of drug were treated with benzol, alcohol and water;

Amount extracted with benzol2.72 per ct.
Amount extracted with alcohol (.889 at 60°)10.00 per ct.
Amount extracted with cold water4.16 per ct.

The benzol residue was dried at a low temperature, that at 110°C. removing volatile oils and traces of moisture. This residue was treated with several portions of warmed acidulated water, this solution giving reactions for an alkaloid, with tannic acid, Mayer's reagent and other test-reagents. Residue was treated with eighty per cent. alcohol (sp. gr. 848 at 60°) dissolving resins leaving a residue of fixed oils, resins and wax.

The following table gives the systematic course of analysis:

Benzol extract contains: Volatile oils driven off at 110° C.50per ct.
Soluble in acid water, reactions for alkaloids.22"
Soluble in alcohol (.848), resins.40 "
Insoluble in alcohol, wax, resins, etc.1.06"

Eighty per cent. alcohol extract contains:

Extractive matter12.65per ct.
Inorganic ash.4"
Matter soluble in water9.00"
Ash soluble in water.50"
Matter sparingly soluble, amorphous.55"

The dried alcoholic extract treated with several portions of absolute alcohol (.7938 at 60°) evaporated to a dry extract contains:

Matter soluble in water, including6.34 per ct.
Tannin, organic acids, some extractives precipitated with lead sub-acetate 1.66 per ct.
Lead removed from solution with H2S filtrate gave reactions for alkaloid with test reagents4.68 per ct.
Insoluble in water1.25 per ct.
Soluble in dilute ammonia hydrate, acid resins.41 per ct.
Insoluble in ammonia hydrate, neutral resins .84 per ct.
Matter insoluble in absolute alcohol contains:
Soluble in water, including 3.55 per ct.
Colors, some extractives precipitated with lead sub-acetate 2.01 per ct.
Matter not precipitated with lead sub-acetate, freed from lead with H2S gave reaction for alkaloid and trace of glucoside 1.54 per ct.
Matter insoluble in water, containing 1.31 per ct.
Soluble in acidulated water, reactions for alkaloids .27 per ct.
Insoluble in acid water, resins, extractives 1.04 per ct.
Total extract 12.65 per ct.

Remaining drug was treated with cold water, yielding 4.16 percent. extract; then with hot water containing sulphuric acid, changing starch into glucose, which was approximately estimated with a standard Fehling solution, showing 1.94 per cent. calculated as starch.

A portion of drug was treated by the U. S. P. process for cinchona assay. The alkaloid solution after neutralizing with sodium hydrate was shaken out with several portions of a mixture of chloroform and ether, and allowed to evaporate at a moderate temperature, yielding 3 per cent. of brownish-yellow amorphous alkaloid, which has a sweetish taste at first, afterward becoming bitter. This alkaloid was treated with dilute sulphuric acid, hydrochloric, tartaric and others, but was unable to obtain crystals from any of the salts. Salts of this alkaloid are freely soluble in water, insoluble in ether or chloroform, are amorphous, forming a white powder when pulverized. Treated with strong sulphuric or nitric acid was unable to notice any colored reactions.

Several pounds of drug were treated with lime water, dried and exhausted with hot alcohol, which on cooling deposited a white amorphous substance, which was treated several times with hot alcohol and allowed to separate out on cooling as a white, crystallizable, tasteless substance, having a low fusing point, freely soluble in chloroform, less soluble in ether and benzin; insoluble in dilute acids and fixed alkalies, and when fused on platinum-foil developes a strong fat-like odor, reminding one of the odor of the fats when fused. A small portion allowed to crystallize from hot alcohol, deposited white, acicular-shaped crystals.

The alkaloid, obtained in different ways, I would suggest to name, Picramnine.

The American Journal of Pharmacy, Vol. 56, 1884, was edited by John M. Maisch.