"The dried milk-juice of Lactuca virosa Linné (Fam. Compositae)." U. S.
Lactucarium Anglicum, Lactucarium Germanicum; Strong-scented Lettuce, Green Endive; Lactucarium, Fr. Cod.; Giftlattichsaft, G.; Lactucario, Sp.
The plants of this genus yield when wounded a milky-juice, to which, indeed, they owe their generic name. The juice from L. sativa, L. virosa, and L. altissima Bieberstein has been supposed to possess narcotic properties.
Lactuca sativa or garden lettuce is an annual plant. The stem, which rises above two feet, is erect, round, simple below, and branching in its upper part. The lower leaves are obovate, undulate and rounded at the summit; the upper are smaller, sessile, cordate, and toothed; both are shining, and of a yellowish-green color. The flowers are pale yellow, small, and- disposed in an irregular terminal corymb. Before the flower-stem begins to shoot, the plant contains a bland pellucid juice, has little taste or odor, and is much used as a salad for the table, but during the period of inflorescence it abounds in a milky juice, which readily escapes from incisions in the stem. The juice is more abundant in the wild than in the cultivated plants. The original native country of the garden lettuce is unknown. The plant has been cultivated from time immemorial, and flourishes equally in hot and temperate latitudes. Some botanists suppose that L. virosa of the old continent is the parent of all the varieties of the cultivated plant.
Lactuca virosa, the acrid or strong-scented lettuce, is biennial, with a stem from two to four feet high, erect, prickly near the base, above smooth and divided into branches. The lower leaves are large, oblong-ovate, undivided, toothed, commonly prickly on the under side of the midrib, sessile, and horizontal; the upper are smaller, clasping, and often lobed; the bracts are cordate and pointed. The flowers are numerous, of a sulphur-yellow color, and disposed in a panicle. The plant is a native of Europe.
It is lactescent, and has a strong disagreeable odor like that of opium, and a bitterish, acrid taste.
Lactucarium is cultivated in Scotland, Germany, Austria and France. According to Fairgrieve (P. J., 1873, iii, p. 972) the plant cultivated in Scotland is the L. virosa, var. montana. From May to August, or even as late as September, the collectors spread over the field cutting the head of each stalk and scraping the flow into their vessels. This is repeated several times daily until the plants are exhausted. The method of cultivation in the Mosel Valley, Germany, is described by Kieffer (Ph. Zeit., i, p. 143), who states that the drug of Germany is shipped to England and later imported into the United States via San Francisco, where it is supposedly used in the adulteration of opium. The cultivation in France is described by Van Italic (J. P. C., 1913, viii, p. 449).
For various plans which have been suggested for collecting the drug, see 14th ed., U. S. D.
Lactucarium, as brought from England, is in small, irregular lumps, about the size of a pea or larger, of a reddish-brown color externally, and of a narcotic odor and bitter taste. As prepared near Edinburgh, it is commonly in roundish, compact, and rather hard masses, weighing several ounces. (Christison.) A variety known in our market as German lactucarium is in pieces about 4 cm. long by 2.5 cm. in thickness, four-sided, with one side convex and the three others flat, or slightly concave from shrinking, as if quarter sections of a saucer-shaped cake which had been divided before it was quite dry. The color on the outer or convex surface is darkish brown, that of the out surfaces light yellowish-brown. From experiments by Parrish and Bakes, the German appears to be inferior to the English, as 44 per cent. of spirituous extract was obtained from the latter, and only 36 per cent. from the former, while the two extracts were about equal in their sensible properties. (A. J. P., 1860, p. 226.) French lactucarium resembles the German, except in being in circular cakes about 4 cm. in diameter. The official description is as follows: "Usually in quarter sections of hemispherical masses, or in irregular, angular pieces; externally dull reddish- or grayish-brown; fracture tough, waxy; internally light brown or yellowish; somewhat porous; odor distinctive, opium-like; taste bitter. Lactucarium is partly soluble in alcohol and ether and, when triturated with water, it yields a turbid mixture. Treat Lactucarium with boiling water and filter; the filtrate is clear while hot; on cooling it becomes turbid but clears upon the addition of ammonia water or alcohol; it is not colored blue by iodine T.S. (starch). An alcoholic solution of Lactucarium gives not more than a faint green color upon the addition of a drop of ferric chloride T.S. (tannin). The powder is grayish-'brown to dark brown, consisting almost entirely of irregular fragments without any cellular structure: when mounted in hydrated chloral T.S., the fragments become clear, showing granular fragments, and from this deposit, numerous rod-shaped crystals and broad monoclinic prisms as well as aggregates of these, all of which polarize light. In the preparation of powdered Lactucarium, dry the crude drug at a temperature not exceeding 70° C. (158° F.). Lactucarium contains not more than 15 per cent. of moisture, and yields not more than 10 per cent. of ash." U. S.
The thridace of Francois, at one time supposed to be identical with lactucarium, is in all probability nothing more than the inspissated expressed juice of lettuce, and, indeed, was directed as such in the French Codex of 1837, the leaves being rejected, and the stalks alone, near the flowering period, being subjected to pressure.
The drug of commerce usually has a growth of mold on the surface. If it has penetrated the drug to any extent it reduces its quality. Occasionally specimens are met with that are moldy throughout, and these should be rejected. In color, taste, and odor, lactucarium bears considerable resemblance to opium, and has sometimes been called lettuce opium. It does not attract moisture from the air. It yields nearly half its weight to water, with which it forms a deep-brown infusion. It is partly soluble in ether and alcohol. From its resemblance in some of its properties and to opium, it was conjectured to contain morphine, or some analogous principle, but this conjecture is false. There is no doubt as to the complexity of the composition of lactucarium, but so feeble are its properties that it has largely gone out of active use, and its chemistry is of little practical importance. Buchner, Aubergier, and Walz claim severally to have discovered the active principle, which has been named lactucin, but the substances obtained by these different chemists are not exactly identical in properties, and the lactucin of Walz and Aubergier is considered by Lenoir as owing its bitterness (to impurities, separated from which it is without taste and inert. For a full account of the earlier analyses of lactucarium, see 16th edition, U. S. D. Ludwig found, in 100 parts, 48.63 of substances insoluble in water, and 51.37 of substances soluble in water. Of the insoluble matter 42.64 parts were of lactucerin or lactucon, in snow-white aggregated granules, dissolving in strong hot alcohol which deposits it on cooling, readily soluble in ether but insoluble in water, incapable of saponiflcation by potassium hydroxide, and therefore not properly a fat, and in alcoholic solution faintly reddening litmus paper. On the other hand, Hesse states that lactucon which, according to Massner, has the composition C26H44O2, is a mixture of esters, of which one, C36H58O2(C2H3O)2, is a diacetyl ester yielding, when saponified, a-lactucerol, C36H60O2, and acetic acid, while the other is a mono-acetyl ester, C36H59O2(C2H3O). Of the 51.37 parts soluble in water, 6.98 were albumen, 1.75 lactucerin, held in solution by other substances, 27.68 bitter extract soluble in water and in alcohol, and 14.96 aqueous extract insoluble in alcohol of 0.830. The former of these extracts was found to contain a peculiar acid substance called lactucic acid, and the lactucin of Aubergier. Lactucic acid is of difficult crystallization, light yellow, strongly bitter, without sour taste, of an acid reaction, and readily soluble in alcohol and water. It has as much claim as any other discovered substance to be considered the active principle of lactucarium.
The assertion sometimes made that Lactuca virosa contains a mydriatic alkaloid has been denied by J. C. Braithwaite and H. E. Stevenson, P. J., 1903, 148. Farr and Wright (P. J., 1904, p. 16) claim, however, to have definitely established the presence of a mydriatic alkaloid, giving alkaloidal reactions with Mayor's and Threshes reagents, and producing a powerful mydriatic effect upon the eye.
Kromayer (Ann. Ch. Ph., cv, p. 3) found also lactucopikrin, C44H32O21, a brown, amorphous, and very bitter substance of weak acid reaction. It is easily soluble in water and alcohol. Ludwig's lactucic acid Kromayer considers to be an oxidation product of lactucopikrin.
Hesse (Handworterbuch, iv, p. 8) prepared lactucerin, and finds it to crystallize in white needles, fusing point 210° C. (410° F.), soluble in hot ligroin, chloroform, and benzene. On fusion with potassium hydroxide it yields acetic acid and lactuceryl alcohol, C18H30O, which forms white needles, fusing at 162° C. (323.6° F.), and is easily soluble in ether, chloroform, and hot alcohol. Hesse has since (Ann. Ch. Ph., 234, p. 243) determined that lactucarium contains the acetates of a- and ß-lactucerol, C18H30O. These compound ethers are saponified with alcoholic potash and water added, which precipitates a- and ß-lactucerol. These are washed, dried in the air, and taken up with boiling alcohol. On cooling, a-lactucerol separates out first and can be purified by recrystallization, while the β-lactucerol is obtained from the mother liquor. The acetate of a-lactucerol fuses at 210° C. (410° F.), while that of β-lactucerol fuses at 230° C. (446° F.). For an examination of Russian lactucarium, by L. Schiperovitch, see Ph. Z. R., or D. C., 1886.
Uses.—The ancients believed that lettuce had soporific properties, and many years ago J. R. Coxe, of Philadelphia, first proposed the employment of the inspissated milky juice as a medicine. It was chiefly, however, through the recommendation by Duncan, Sr., of Edinburgh, that the medicine came into use and was adopted as official in various pharmacopoeias. It is claimed for it that it has, although in a very much inferior degree, the anodyne and calming properties of opium, without its disposition to derange the digestive organs. It has been employed in this country to some extent to allay cough and quiet nervous irritation, but we believe that the general experience is in accord with our own in finding it to be almost devoid of narcotic properties. We have never been able to obtain any good results from its use. Water distilled from lettuce (eau de laitue) is used in France as a mild sedative, in the quantity of from two to four ounces. The fresh leaves boiled in water are sometimes employed in the shape of cataplasm. It is said that in Egypt a mild oil is derived from the seeds, fit for culinary use. (See Syrupus Lactucarii.)
Dose, ten to twenty grains (0.65-1.3 Gm.), but much larger quantities may be given without obvious effects.
The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.