Coto is a bark of unknown botanical source, derived from a large tree, probably belonging to a species of Cryptocarya (N.O. Laurineae) (Nope - it's Aniba coto (Rusby) Kosterm. -Henriette). It is obtained from Bolivia. The bark occurs in flat or slightly curved heavy pieces, up to about 60 centimetres long, 6 centimetres broad, and 8 to 14 millimetres thick. The external surface is of a cinnamon-brown colour, with occasional white patches, and deep longitudinal fissures and transverse cracks. The inner surface is brown and coarsely striated. The fracture is short and granular in the outer part of the bark, but coarsely fibrous elsewhere. The transverse section exhibits a thin brown cork and a narrow brown cortex, separated from the thick bast by a line of sclerenchymatous cells; the bast also contains groups of sclerenchymatous cells. The bark has a characteristic odour and a pungent taste. The drug originally imported under the name of coto, and now distinguished as true coto, so closely resembles the above that it cannot be distinguished by appearance, odour, taste, or structure. If, however, the powdered true coto be shaken with ether, the ethereal solution distilled in presence of water, and the resulting aqueous solution freed from fat with petroleum spirit and evaporated to dryness, the residue will give with nitric acid a blood-red colour, whereas paracoto bark gives a yellow colouration.
Constituents.—The chief constituent of coto (paracoto) bark is paracotoin (dioxymethylene-phenylcumalin), a crystalline bitter principle, which gives a yellow colour with nitric acid; other constituents are leucotin, hydrocotoin (benzoyl-phloroglucinol dimethyl ether), methyl hydrocotoin, protocotoin, methyl protocotoin (oxy-leucotin), and piperonylic acid. So-called true coto bark contains cotoin (benzoyl-phloroglucinol methyl ether), a crystalline powder, which yields a red colour with nitric acid, and leucotin (phenylcumalin). Both barks also contain a little volatile oil, resin, and tannin.
Action and Uses.—Coto bark is said to increase the appetite, and the absorption of fluid by the intestinal mucosa, possibly by vaso-dilatation. It is used in the treatment of diarrhoea, including the diarrhoea of phthisis and typhoid, marasmus, and intestinal catarrh. A tincture and a liquid extract of coto are made, the former being the better known preparation. It is prescribed, with aromatic chalk powder or chalk mixture, in cholera, diarrhoea, and dysentery. For use in pills or powders, the active principle cotoin is preferred.
Dose.—1/2 to 5 decigrams (1 to 8 grains).
- Extractum Coto Liquidum, B.P.C.—LIQUID EXTRACT OF COTO. 1 in 1.
- Dose.—3 to 10 decimils (0.3 to 1.0 milliliters) (5 to 15 minims).
- Mistura Coto, B.P.C.—COTO MIXTURE. Syn.—Dr. Burney Yeo's Coto Mixture.
- Each fluid ounce contains 10 minims each of liquid extract of coto and compound tincture of cardamoms, with mucilage of gum acacia, syrup, and distilled water. Dose.—15 to 30 mils (1/2 to 1 fluid ounce).
- Tinctura Coto, B.P.C.—TINCTURE OF COTO. 1 In 10.
- Used chiefly in diarrhoea and intestinal catarrh. Dose.—1/2 to 2 mils (10 to 30 minims).
C12H8O4 = 216.064.
Cotoin, C12H8O4, is a bitter principle obtained from coto bark by making an ethereal extract from the powdered bark, treating it with warm benzin, and allowing the mixture to stand till clear. The clear liquid, on spontaneous evaporation, yields cotoin in crystals. It occurs in the form of yellowish-white, acicular crystals, resembling gallic acid, or as a pale-yellow powder, bitter and acrid, its dust causing sneezing and coughing. Melting-point, 149° to 151°. Optically inactive. It dissolves in alkalies with a yellow colour; in sulphuric acid with a yellowish-brown colouration; in nitric acid with a yellow colouration. Ferric chloride blackens a dilute solution of cotoin. It reduces silver salts in the cold, and Fehling's solution on heating. True cotoin, C14H12O4, has a melting-point of 130° to 131°, and gives a blood-red colouration with nitric acid.
Sparingly soluble in water, alcohol, chloroform, ether, carbon bisulphide, benzol, or acetone.
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.