The inspissated juice of the leaves of Aloe Perryi Baker, yielding Socotrine Aloes; or Aloe vera Linné, yielding Curaçoa Aloes; or of Aloe ferox Miller, yielding Cape Aloes, U.S.P.
BOTANICAL CHARACTERISTICS.—Succulent plants with spicate inflorescence; perianth tubular; style equal in length to the stamens, or almost wanting. Capsule membranous, scarious; seeds in two rows, flattened or 3-cornered, winged. Cape of Good Hope, etc. The American aloe, or century plant (Agave americana), is a plant quite similar to the above.
COLLECTION.—The bitter, yellow, succulent portion of the leaf (which, when inspissated, constitutes the aloes of commerce) is found in thin-walled ducts near the surface. The thick leaves are cut off near the base (March and April) and stood up in the sun to drain upon skins. Impurities are removed by skimming with a ladle, etc. Artificial heat is sometimes used for evaporation. When of proper consistence, the evaporate is transferred to kegs, monkey skins, or boxes, and shipped by way of Bombay and Zanzibar.
Socotrine (Zanzibar) is a highly esteemed article, comes in yellowish-brown masses, sometimes soft, odor aromatic, saffron-like, never fetid or putrid and a nauseous and bitter taste, easily broken into pieces with conchoidal fracture and sharp edges, readily splinters. Does not possess any crystalline characteristics under the microscope.
Curaçoa, from the Dutch West Indies, is preferred by some to Socotrine. This variety comes in orange to blackish-brown, opaque masses, fracture surface, uneven, waxy, somewhat resinous; odor, characteristic but not aromatic as in the socotrine variety.
Cape Aloes, the South African Aloes, comes in reddish-brown or olive-black masses, usually covered with a yellowish dust, in thin fragments, transparent and of a reddish-brown color; fracture, smooth and glassy; odor, quite characteristic.
CONSTITUENTS.—The active principle of these different aloes is a bitter neutral principle having the general name of aloin, but slightly differing in each variety, forming possibly a homologous series; these aloes may be distinguished by their characteristic reactions with different reagents. It should be stated that the various processes of assay for aloes thus far proposed give discordant results. A small percentage of emodin is found in various varieties. Cape aloes contains 0.8 per cent. of this principle. Ash, not exceeding 4 per cent.
70a. ALOE BARBADENSIS.—BARBADOES ALOES. Prepared from the leaves of Aloe chinensis, Steud and A. Vera, L. by boiling the juice or by making a decoction of the leaves; it is inferior to the other varieties. Its color varies, but it is usually dark brown, approaching to black, opaque even at the edges, and with a dull fracture; it is further distinguished by its nauseous odor. A solution of 1 part in 100,000 of distilled water produces a fine rose color on the addition of gold chloride or tincture of iodine, all the others, except Natal aloes, producing only a slow change, a feeble color, or no color whatever.
TESTS.—SOCOTRINE. The powder (dark brown) when mounted under the microscope in almond oil, shows yellowish- to reddish-brown, irregular or angular fragments; upon addition of nitric acid yields a yellowishto reddish-brown solution.
CURAÇOA.—Powder (deep reddish brown) when treated as above shows numerous blackish brown more or less opaque and angular fragments; with nitric acid, yields a deep red liquid immediately.
CAPE.—Powder (greenish-yellow changing to light brown on aging). When treated as above and mounted under microscope it shows numerous distinctly angular bright yellow fragments. Nitric acid produces a reddish-brown liquid changing to purplish brown and finally greenish.
GENERAL TEST.—Intimately mix 1 Gm. of Aloes with 10 mils of hot water and dilute 1 mil of this mixture with 100 mils of water; a green fluorescence is produced upon the addition of an aqueous solution of sodium borate (1 in 20). Dilute 1 mil of the original aqueous mixture of Aloes with 100 mils of water, and shake it with 10 mils of benzene; upon separating the benzene solution and adding to it 5 mils Of ammonia water a permanent deep rose color is produced in the lower layer, U.S.P. IX.
In the case of liquids it is best to evaporate about 10 mils, more or less, to a pasty consistency in a porcelain dish, acidulate, and extract from the dish with about 10 mils of ether by stirring with a glass rod and pouring off the ether into a test-tube. With pills or other solid material it is necessary only to powder, acidulate and extract as described. To this extract an equal volume of saturated borax solution is added, etc., U.S.D.A.
Preparation of Aloin.—From some varieties of aloes it is obtained by digesting in alcohol for twenty-four hours; then boil, filter, and set aside to crystallize. Can also be obtained by dissolving aloes (Barbadoes or Curaçoa) in acidulated boiling (HCl) water, and, when cold, resin will deposit; decant, evaporate, and set aside for two weeks, when aloin will crystallize. Shaking the crystals with acetic ether removes adhering resin. Dose: 2 to 5 gr. (0.12 to 0.32 Gm.). (See also 70 e.)
ACTION AND USES.—Cathartic and emmenagogue. As a cathartic aloes is slow in action but certain, having a peculiar affinity for the large intestine; it has produced beneficial effects as a cholagogue; as an emmenagogue it is extensively employed in amenorrhea. Dose: 2 to 5 gr. (0.13 to 0.3 Gm.).
- OFFICIAL PREPARATIONS.
- Extractum Aloes, . . . Dose: 3 to 10 gr. (0.2 to 0.6 Gm.).
- Tinctura Aloes (10 per cent. with glycyrrhiza 20 per cent.), . . . 5 to 10 <minim> (0.3 to 0.6 mil); 1/2 to 4 fl. dr. (2 to 8 mils).
- Tinctura Benzoini Composita (2 per cent. of aloes), . . . 10 to 40 <minim> (0.6 to 2.6 mils).
- Extractum Colocynthidis Compositum (50 per cent.), . . . 5 to 25 gr. (0.3 to 1.6 Gm.).
- Pilulae Aloes (about 2 gr. in each pill), . . . 2 to 5 pills.
- Pilulae Rhei Compositae (aloes 1 1/2 gr. in each pill), . . . 1 to 3 pills.
70e. ALOINUM.—ALOIN (U.S.P. IX). A neutral principle from several varieties of aloes, chiefly Barbadoes aloes (yielding barbaloin), C17H20O7, and Socotra or Zanzibar aloes (yielding socaloin), C15H16O7, U.S.P. Nataloin, C16H18O7, while not official, is a similar product. Minute acicular crystals, or a microcrystalline powder, yellow to yellowish-brown, of a slight odor and characteristic bitter taste. Barbaloin, soluble in 470 parts of ether; socaloin, soluble in 380 parts of ether. Both soluble in water and alcohol. It is rapidly decomposed in alkaline solution. Dose: 1 gr. (0.6 Gm.). Ash, not more than 0.5 per cent.
A Manual of Organic Materia Medica and Pharmacognosy, 1917, was written by Lucius E. Sayre, B.S. Ph. M.