Frangula. U. S. Frangula.
Frang. [Buckthorn Bark]
"The dried bark of Rhamnus Frangula Linne (Fam. Rhamnaceae)." U. S.
Rhamni Frangulae Cortex, Br. (1885); Frangula Bark; Alder Buckthorn; Ecorce de Bourdaine, Bourgene, Fr.; Cortex Frangulae, P. G.; Faulbaumrinde, G.; Corteccia di frangola. It.
R. Frangula or Alder Buckthorn is an erect glabrous shrub from ten to fifteen feet high, without thorns, with broadly ovate obtuse leaves, the margins being entire or slightly sinuate, the under side sometimes slightly downy, and the rather numerous lateral veins diverging equally almost from the whole length of the midrib. Flowers all hermaphrodite, two or three together in each axil, with the calyx teeth, petals, and stamens in fives. Fruit dark purple, the size of a pea. This plant grows in hedges and bushy places throughout Europe and Russian Asia, except in the far north. It has become established on Long Island, northern New Jersey and in Ontario.
It is probable that most of the species of the genus Rhamnus have cathartic properties. An article upon R. Purshiana will be found elsewhere, as it is official in both of the Pharmacopoeias. (See Cascara Sagrada.) The R. catharticus Linn., or common buckthorn, grows in Europe along with the official species, and has become locally naturalized in the Eastern portions of the United .States. Its bark is probably often sold for the official article. It is distinguished by its more spreading, thorny habit, and its dioecious flowers, which are thickly clustered in the axils and have their parts in fours. The leaves also are more acute, have their margins finely serrate and their lateral veins mostly proceeding from the proximal half of the midrib. The fruit is purplish-black.
Properties.—This bark is officially described as "in quills varying in length, frequently flattened or crushed; from 0.5 to 1 mm. in thickness; outer surface grayish-brown or purplish-black, with numerous, prominent, lighter-colored, transverse lenticels and occasional patches of foliaceous lichens bearing small, blackish apothecia; inner surface smooth, dark brown with occasional purplish blotches, longitudinally striate, becoming red when moistened with solutions of the alkalies; fracture short, slightly fibrous in the inner layer; odor distinctive; taste slightly bitter. Under the microscope, transverse sections of Frangula show a distinctly undulate corky layer, composed of about 12 rows of reddish-brown cells; parenchyma cells of the primary cortex with numerous rosette aggregates of calcium oxalate, from 0.01 to 0.025 mm. in diameter; inner bark with bast-fibers in narrow, interrupted rows, the groups of fibers being separated radially by the medullary rays; bast-fibers with thick, strongly lignified, yellowish walls and narrow lumina and each group surrounded by a layer of crystal fibers, the prismatic crystals of calcium oxalate varying from 0.007 to 0.015 mm. in diameter, medullary rays one to two cells in width, occasionally three; cells of the parenchyma and medullary rays with numerous starch grains, 0.003 mm. in diameter. The powder is yellowish-brown; stone cells absent (distinguishing it from the powder of Cascara Sagrada). Add 0.1 Gm. of powdered Frangula to 10 mils of hot distilled water, shake the mixture occasionally until cold and filter; on the addition of a few drops of ammonia water, the filtrate is colored a deep red. Macerate 0.1 Gm. of powdered Frangula with 10 drops of alcohol, boil with 10 mils of distilled water and filter when cold. Shake this filtrate with 10 mils of ether; a yellow, ethereal solution separates, and 3 mils of this ethereal solution, when shaken with 3 mils of ammonia water, yields an alkaline solution, which, on being diluted with 20 mils of distilled water, still possesses a distinct cherry-red color. Frangula yields not more than 6 per cent. of ash." U. S.
As first pointed out by Schrenk (Am. Drug., April, 1887), the bark of Rhamnus Frangula can be distinguished from that of R. Purshiana (Cascara Sagrada) by the absence of the. irregular angular sclerenchymatous cells, which in R. Purshiana are wedged together in large compact groups, increasing in size and number towards the surface, and causing the short fracture of the outer bark.
Tschirch and Pool (S. W. P., 1908, p. 665) have made a comparative pharmacognostical and chemical study of the barks of R. Frangula and R. Purshiana. Wurffel (Zeit. Oest. Apoth. Ver., 1907, p. 211) and Mitlacher (Bull. sc. pharmacol., 1911, p. 10) report the substitution of Frangula by the bark of an alder (Alnus glutinosa Medic). The latter may be detected by not being reddened with solutions of the alkalies. Mitlacher (Ph. Post, 1905, p. 751) and Moser (A. J. P., 1909, p. 580) have found that the official Frangula is either admixed with or entirely substituted by the bark of R. carniolica A. Kerw. E'we (Proc. A. Ph. A., 1914, p. 131) obtained a sample of Frangula which proved to be wild-cherry bark.
It is not certainly known which of the several bodies isolated from frangula bark is the purgative principle. The most important body, frangulin, the rhamnoxanthin (C20H20O10) of Buchner and Binswanger, may be obtained by Phipson's process by macerating the bark for three or four days in carbon disulphide, then permitting the liquid to evaporate, exhausting the residue with alcohol, which leaves the fatty matter behind, evaporating the alcoholic liquid to dryness, and recrystallizing from ether. As thus obtained it is in fine yellow crystals, melting at about 226° C. (438.8° F.), and subliming in golden-yellow needles. It is insoluble in water, soluble in 160 parts of warm 80 per cent. alcohol, nearly insoluble in cold alcohol, soluble in hot fixed oils, petroleum benzin, and oil of turpentine. It communicates its color to cotton, silk, and wool. Faust (A. Pharm., clxxxvii, 8) first proved the glucosidal character of frangulin by boiling it in alcoholic solution with hydrochloric acid, obtaining glucose and frangulinic acid, C14H8O4. This forms fine microscopic needles of reddish color, fusing at 248° to 250° C. (478.4°-482° F.). Liebermann and Waldheim (Ber. d. Chem. Ges., 9, p. 1775) obtained in this decomposition instead of frangulinic acid, emodin, C15H10O5. trioxymethylanthraquinone. Frangulinic acid, on the other hand, would be a dioxyanthraquinone and an isomer of alizarin. Schwabe, in 1888, also found that emodin and rhamnodulcite were the decomposition products of frangulin, to which latter he gave the formula C21H20O9, instead of that given above by Buchner. (Planchon et Collin, Drogues Simples (1896), vol. ii, 590.) E. Amweg has devised a method of separating the glucosides from frangula, cascara and rhubarb by extraction with solvents; he uses, 1, benzene; 2, a mixture of two parts of benzene, and one part of absolute alcohol, and 3, alcohol (60 per cent.) (Ap. Ztg., 1897, 747.) Kubly isolated a crude acid which, when purified, he termed frangulic acid; Amweg regards this acid as a decomposition product and calls it pseudo-frangulin, this when hydrolyzed becomes pseudo-emodin, The emetic action of the green bark is attributed to a hydrolytic ferment, which is destroyed by heating. (P. J., 1898, 24.)
Tschirch and Bromberger state that the bark of Rhamnus cathartica was found to contain rhamnosterin, rhamnofluorin, emodin, chrysophanol and d-glucose. (S. W. P., 1912, v. 50, pp. 193-197.)
Uses.—In its fresh state this drug is very irritant to the gastro-intestinal mucous membrane, producing, when taken in sufficient quantity, violent catharsis, accompanied by vomiting and much pain. During drying it is said to lose much of its irritant power, and the dried bark is affirmed to resemble rhubarb in its action. The U. S. P. VIII required that the bark should be at least one year old, but this requirement does not appear in the U. S. P. IX. A decoction (an ounce to the pint) may be used in tablespoonful doses, or a dessertspoonful of an elixir, made by mixing four fluidounces of the fluidextract with twelve of elixir of orange, may be employed.
Dose, of frangula, fifteen to thirty grains (1-2 Gm.).
Off. Prep.—Fluidextractum Frangulae, U. S.; Elixir Catharticum Compositum (from Fluidextract), N. F.; Syrupus Sennae Compositus (from Fluidextract), N. F.