333. Frangula.
The dried bark of Rham'nus fran'gula Linné, collected at least one year before using.
BOTANICAL CHARACTERISTICS.—An elegant arborescent shrub, known as the berry-bearing alder. Leaves entire, with about 7 pairs of nearly opposite parallel veins. Flowers perfect, style simple; the fleshy berry is round, red, and on ripening becomes black and juicy.
HABITAT.—Europe and Northern Asia.
DESCRIPTION OF DRUG.—Quilled, about 1 mm. (1/25 in.) thick; outer surface grayish-brown, or blackish-brown, with numerous small, whitish, transversely-elongated lenticels and occasional patches of foliaceous lichens; inner surface smooth, pale brownish-yellow; fracture in the outer layer short, of a purplish tint; in the inner layer fibrous and pale yellow; when masticated, coloring the saliva yellow; odor distinct; taste sweetish and bitterish.
Medullary rays not converging at the outer ends (distinction from Rhamnus Purshiana); stone cells absent (distinction from Rhamnus Purshiana and Rhamnus Californica).
CONSTITUENTS.—Frangulin, or rhamno-xanthin, C20H20O10, is a crystalline, lemon-yellow, odorless, tasteless glucoside; and emodin, a reddish principle, exists in the old bark; these develop by age. Two products are obtained from frangulin by hydrolysis—emodin, C15H10O5. and rhamnose, C6H12O5. Frangula-emodin differs from the rhubarb-emodin in melting-point, and in some color reactions. Senna and aloes also contain an isomeric emodin. (See Rhamnus Purshiana.) Ash, not exceeding 6 per cent.
Preparation of Frangulin.—Macerate the bark for four days in carbon disulphide. Evaporate; exhaust residue with alcohol; evaporate alcoholic solution to dryness; crystallize from ethereal solution. Forms sublimable yellow crystals; becomes purple when treated with alkalies. Dyes cotton, silk, wool, etc., yellow.
ACTION AND USES.—A mild laxative or cathartic, acting like senna and often used in its stead. Dose: ½ to 2 dr. (2 to 8 Gm.).
OFFICIAL PREPARATION.
- Fluidextractum Frangulae Dose: ⅓ to 2 fl. dr. (1.3 to 8 mils).
