Preparations: Tincture of Bitter Orange Peel - Tincture of Fresh Orange Peel - Fluid Extract of Bitter Orange Peel - Compound Infusion of Orange Peel - Wine of Orange
Related entries: Aurantii Dulcis Cortex (U. S. P.)—Sweet Orange Peel - Aurantii Flores.—Orange Flowers - Limon.—Lemon - Oleum Bergamottae (U. S. P.)—Oil of Bergamot - Oleum Aurantii Corticis (U. S. P.)—Oil of Orange Peel
"The rind of the fruit of Citrus vulgaris, Risso"—(U. S. P.) (Citrus Aurantium, var. amara, Linné; Citrus Bigaradia, Duhamel).
COMMON NAMES: Bitter orange, Bigarade orange, Seville orange.
ILLUSTRATION: Bentley and Trimen, Med. Plants, 50.
Botanical Source.—The bitter orange tree is scarcely distinguishable botanically from the sweet orange tree (see Aurantii Dulcis Cortex), except in its leaves, fruit, and flowers. The leaf stalk of the bitter orange is more broadly winged, and the fruit itself of deeper hue of red, having a rougher rind, and a bitter, sour juice. Added to these characteristics all portions of the bitter orange emit a greater fragrance than the same parts of the sweet variety. By some botanists this tree is regarded merely as a variety of the Citrus Aurantium of Linné (see Aurantii Dulcis Cortex).
Description.—I. THE RIND (Aurantii amari cortex). The U. S. P. describes bitter orange peel as consisting of "narrow, thin bands, or in quarters; epidermis of a dark, brownish-green color, glandular, and with very little of the spongy, white, inner layer adhering to it; it has a fragrant odor, and an aromatic, bitter taste"—(U. S. P.). (For further information regarding bitter orange, see Aurantii Dulcis Cortex.) It is official in Extractum Aurantii Amari Fluidum and in Tinctura Aurantii Amari of the U. S. P.
II. THE FRUIT (Fructus aurantii), when ripe, is about the shape and size of the common sweet orange, is darker in color, rougher, and has a white parenchyma beneath the rind, and the juice of the pulp is bitter and sour. Orangettes (petit grains) are the unripe fruits which drop from the trees, and are considerably used on the continent under the name of orange berries. They vary from ⅛ to ½ inch in diameter, are of a greenish or brown-black color, closely wrinkled, and pleasantly aromatic both in taste and odor.
III. THE LEAVES (Folia aurantii).—These are borne on a jointed, broadly-winged petiole, and are smooth, oblong-ovate or ovate, nearly entire, or having a slightly crenated margin. They are aromatic and have pellucid oil-glands scattered throughout the blade.
Chemical Composition.—A bitter crystalline body was isolated in 1828 by Lebreton and named hesperidin. It exists in the white parenchymatous tissues of both the orange and lemon rind, but is found in greatest abundance in the unripe Seville orange. It occurs, when purified, in white, acicular crystals, practically insoluble in water, even when hot (1 in 5000 of boiling water). It dissolves in boiling acetic acid and in alcohol, but refuses to dissolve in ether, fats, essential oils, and benzol. Treated with diluted acids it is split into grapesugar and hesperetin, insoluble in alcohol. Hesperidin fuses at 245° C. (473° F,); hesperetin at 223° C. (433.4° F.). A substance analogous to tannin, gum, resin, albumen, fixed oil, and an essential oil (see Oleum Aurantii Corticis) have also been found in the rind.
The juice of the orange consists chiefly of sugar, mucilage, and citric acid. Tanret (1886) found in bitter orange peel a bitter, acrid resin, a crystallizable, tasteless acid having the formula C44H28O14, hesperidin, an isomeric glucoside (isohesperidin, C44H26O24.5H2O) and another glucoside (aurantiamarin), to which he attributes the bitterness of the rind on account of its solubility in water.
Action and Medical Uses.—(See Aurantii Dulcis Cortex.)