Uses—In America, wild cherry bark is held in high estimation for its mildly tonic and sedative properties. It is administered most appropriately in the form of cold infusion or syrup, the latter being a strong cold infusion, sweetened; a fluid extract and a dry resinoid extract are also in use. The bark is said to deteriorate by keeping, and should be preferred when recently dried.
FOLIA LAURO-CERASI.
Common Laurel or Cherry-laurel Leaves; F. Feuilles de Laurier-cerise; G. Kirschlorbeerblätter.
Botanical Origin—Prunus Lauro-cerasus L., a handsome evergreen shrub, growing to the height of 18 or more feet, is a native of the Caucasian provinces of Russia (Mingrelia, Imeritia, Guriel), of the valleys of North-western Asia Minor, and Northern Persia. It has been introduced as a plant of ornament into all the more temperate regions of Europe, and flourishes well in England and other parts, where the winter is not severe and the summer not excessively hot and dry.
History—Pierre Belon, the French naturalist, who travelled in the East between 1546 and 1550, is stated by Clusius[970] to have discovered the cherry-laurel in the neighbourhood of Trebizond. Thirty years later, Clusius himself obtained the plant through the Imperial ambassador at Constantinople, and distributed it from Vienna to the gardens of Germany. Since it is mentioned by Gerarde[971] as a choice garden shrub, it must have been cultivated in England prior to 1597. Ray,[972] who like Gerarde calls the plant Cherry-bay, states that it is not known to possess medicinal properties.
In 1731, Madden of Dublin drew the attention of the Royal Society of London[973] to some cases of poisoning that had occurred by the use of a distilled water of the leaves. This water he states had been for many years in frequent use in Ireland among cooks, for flavouring puddings and creams, and also much in vogue with dram drinkers as an addition to brandy, without any ill effects from it having been noticed. The fatal cases thus brought forward occasioned much investigation, but the true nature of the poison was not understood till pointed out by Schrader in 1803 (see art. Amygdalæ amaræ, [p. 248, note 2]). Cherry-laurel water, though long used on the Continent, has never been much prescribed in Great Britain, and had no place in any British Pharmacopœia till 1839.
Description—The leaves are alternate, simple, of leathery texture and shining upper surface, 5 to 6 inches long by 1¾ to 2 inches wide, oblong or slightly obovate, attenuated towards either end. The thick leafstalk, scarcely half an inch in length, is prolonged as a stout midrib to the recurved apex. The margin, which is also recurved, is provided with sharp but very short serratures, and glandular teeth, which become more distant towards the base. The under side, which is of a paler colour and dull surface, is marked by 8 or 10 lateral veins, anastomosing towards the edge. Below the lower of these and close to the midrib, are from two to four shallow depressions or glands, which in spring exude a saccharine matter, and soon assume a brownish colour. By the glands with which the teeth of the serratures are provided, a rather resinous substance is secreted.[974]
The fresh leaves are inodorous until they are bruised or torn, when they instantly emit the smell of bitter almond oil and hydrocyanic acid. When chewed they taste rough, aromatic and bitter.
Microscopic Structure—The upper surface of the leaf is constituted of thin cuticle and the epidermis made up of large, nearly cubic cells. The middle layer of the interior tissue exhibits densely packed small cells, whereas the prevailing part of the whole tissue is formed of larger, loose cells. Most of them are loaded with chlorophyll; some enclose crystals of oxalate of calcium.
Chemical Composition—The leaves when cut to pieces and submitted to distillation with water, yield Bitter Almond Oil and Hydrocyanic Acid, produced by the decomposition of Laurocerasin. This is an amorphous yellowish substance isolated by Lehmann (1874) in Dragendorff’s laboratory. He extracted the leaves with boiling alcohol, and purified the liquid by gently warming it with hydroxide of lead. From the liquid, crude laurocerasin was precipitated on addition of ether; it was again dissolved repeatedly in alcohol and precipitated by ether. The yield of the leaves is about 1⅓ per cent. Laurocerasin is readily soluble in water, the solution deviates the plane of polarization to the left, yet not to the same amount as amygdalin. The molecule of laurocerasin, C₄₀H₆₇NO₃₀, would appear to include those of amygdalin, C₂₀H₂₇NO₁₁, amygdalic acid, C₂₀H₂₆O₁₂ and 7 OH₂.