"A volatile oil distilled from the leaves of Melaleuca Leucadendron, Linné (Nat. Ord.—Myrtaceae). It should be kept in well-stoppered bottles, in a cool place"—(U. S. P.).
SYNONYMS: Oleum cajeputi, Oil of cajeput, Oleum Wittnebianum.
Botanical Source and History.—This oil is distilled from the leaves of Melaleuca Leucadendron, a tree growing in the Moluccas and adjacent islands. It is variously known as White tea-tree, Broad-leaved tea-tree, Paper-barked tea-tree, Swamp tea-tree, and White-wood. It is a small tree, with a tolerably erect but crooked trunk; a soft, thick, spongy, whitish, ash-colored bark; and scattered branches, with the slender twigs often drooping as completely as in the weeping willow (Salix Babylonica). The leaves are alternate, most frequently vertical, short-stalked, narrow- lanceolate, while young, sericeous, sometimes slightly falcate, entire, from 3 to 5 inches long, and from 1/2 to 3/4 of an inch broad; and very aromatic when bruised. The flowers are ternate, sessile, small, white, scentless, in terminal and axillary, downy spikes; the bracts are solitary, lanceolate, silky, and caducous. Calyx urceolate. Corolla white and orbicular; filaments 30 to 40, much longer than the petals; anthers ovate-cordate, with a yellow gland on the apex. The style is somewhat longer than the stamens; the stigma obscurely 3-lobed. The capsules are 3-celled and 3-valved; the seeds numerous, and angularly wedge-shaped (L.). This tree is the Melaleuca Cajuputi of Roxburgh, and the Melaleuca minor of De Candolle. By Bentham, it is regarded as a variety of Melaleuca Leucadendron. Several other species of Melaleuca, as M. latifolia, M. viridifolia, and M. hypericifolia, yield closely related oils, while an extract prepared from the M. paraguayensis (I couldn't find such a plant. -Henriette) has been used in rheumatic and allied complaints.
Preparation and Description.—Cajuput oil is obtained by distillation of the leaves, which are collected in autumn, allowed to steep for a night in water, and then distilled in copper vessels. The yield is very small. It is imported from the East Indies in green-glass bottles. The U. S. P. describes it as "a light, thin, bluish-green, or, after rectification, colorless liquid, having a peculiar, agreeable, distinctly camphoraceous odor, and an aromatic, bitterish taste. Specific gravity, 0.922 to 0.929 at 15° C. (59° F.). With an equal volume of alcohol it affords a clear solution, which either has a slightly acid reaction, or, in the case of the rectified oil, is neutral to litmus paper"—(U. S. P.). The odor of the oil has been stated to resemble the combined fragrance of camphor, rosemary, and cardamom. The green color is not essential, and may be removed by distillation; it is due chiefly to the presence of copper, and partly to the presence of some altered chlorophyll. The oil is slightly laevogyre. Sulphuric and nitric acids have but little action on cajuput oil.
Adulterations and Tests.—In consequence of its high price, oil of cajuput is subject to adulteration. Oils of rosemary or turpentine, combined with camphor and bruised cardamom seeds, and appropriately tinted with milfoil resin, have been sold as genuine oil. Oil of camphor has been used as an adulterant. Oils of lavender, origanum, and rosemary frequently serve for adulteration, but are distinguished by the energetic action of a solution of iodine, besides, all would materially affect the nature of the residue of the iodine test subsequently described. "On shaking 5 Cc. of the oil with 5 Cc. of water containing a drop of diluted hydrochloric acid, the oil loses its green tint and becomes nearly colorless. If to this acid liquid, separated from the oil, a drop of potassium ferrocyanide T.S. be added, a reddish-brown color will usually be produced (presence of traces of copper). If 5 parts of the oil be heated to 60° C. (122° F.), and 1 part of powdered iodine gradually added, with avoidance of any further rise of temperature, the mixture, on cooling, will deposit a mass of crystals"—(U. S. P.).
Chemical Composition.—The chief constituent of cajuput oil is cineol (cajeputene hydrate, cajeputol C10H18O) (Blanchet, 1833; Wallach, 1884), terpineol (C10H18O), both free and as an ester of acetic acid, and small amounts of terpenes, such as laevo-pinene. The lowest fraction of the crude oil contained valeric aldehyde and benzoic aldehyde (Voiry, 1888). (For interesting details regarding this oil, see Gildemeister and Hoffmann, Die Aetherischen Oele, 1899.)
CINEOL (Eucalyptol, C10H16O) is a constituent of many essential oils. It is a colorless liquid, of a characteristic camphoraceous odor, optically inactive, boils at 177° C. (350.6° F.), congeals at a temperature slightly below the freezing point of water, and forms a characteristic addition product with hydrobromic acid which is decomposable by water into its constituents.
Action, Medical Uses, and Dosage.—Cajuput oil is a powerful diffusive stimulant, diaphoretic and antispasmodic. When swallowed, it occasions a warmth in the stomach, with an increased action of the pulse, and occasionally diaphoresis. It is very much valued in the islands of the Indian Ocean, the inhabitants of which employ it extensively in rheumatism, palsy, epilepsy, and many other diseases; using it both internally and as a local application. It may be advantageously employed internally in chronic rheumatism, hysteria, colic, spasms or cramps of the stomach or bowels, cholera morbus, Asiatic cholera, congestive dysmenorrhoea hiccough, nervous dysphagia, in the typhoid stage of fevers, in nervous vomiting, and wherever a powerful stimulant is required. It also appears to be useful in removing worms, and in chronic affections of mucous tissues, being especially useful in chronic laryngitis and chronic bronchitis, as well as catarrh of the bladder. It should never be given internally when inflammation is present. Externally, it is very beneficial as an application to rheumatic, neuralgic and other pains, nervous headache, and may be used alone, or in combination with other oils. It has likewise been found efficient as a local application in gutta rosea, parasitic and other cutaneous maladies. Applied to the cavity of a carious tooth, it alleviates toothache The dose is from 1 to 10 drops, on sugar, in emulsion, or in sweetened brandy and water. Externally, it may be applied 3 or 4 times a day.
King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.