Oleum Ricini. U. S., Br. Castor Oil.

Botanical name: 

Ol. Ricin.

"A fixed oil obtained from the seeds of Ricinus communis Linné (Fam. Euphorbiaceae). Preserve it in well-closed containers." U. S. "Castor Oil is the oil expressed from the seeds of Ricinus communis, Linn." Br.

Huile de Ricin, Fr. Cod.; Oleum e semine Ricini, Fr.; Oleum Ricini, P. G.; Ricinusöl, G.; Olio di ricino, It.; Aceite de ricino; Oleum Palmae Christi, Sp.

The castor oil plant, or palma Christi, is a native of India and is now extensively cultivated in the warmer regions throughout the world. In India there are about seventeen different varieties grown which are grouped into two types. (1) The one consisting of tall shrubs or small trees, being usually planted as a shade for other crops and yielding large seeds which contain an abundance of inferior oil. (2) The second type includes the herbaceous annuals, which, while they produce small yields, yield a much better grade of fixed oil.

The following description applies to the plant as cultivated in cool latitudes. The stem is of vigorous growth, erect, round, hollow, smooth, glaucous, somewhat purplish towards the top, branching, and from three to eight feet or more in height. The leaves are alternate, peltate, palmately six to eleven lobed, the lobes acute or acuminate and serrate, smooth on both sides, and of a bluish-green color. The flowers are monoecious, stand upon jointed peduncles, and form a pyramidal terminal raceme, of which the lower portion is occupied by the male flowers, the upper by the female. Both are destitute of corolla. In the staminate flowers the calyx is divided into five oval, concave, pointed, reflected, purplish segments, and encloses numerous stamens, united into fasciculi at their base. In the pistillate the calyx has three or five narrow lanceolate segments, and the ovary, which is roundish and three-sided, supports three linear, reddish stigmas, forked at their apex. The fruit is a roundish, glaucous capsule, with three projecting sides, covered with tough spines, and divided into three loculi, each containing one seed, which is expelled by the bursting of the capsule. This species of Ricinus is a native of the East Indies and Northern Africa, naturalized in the West Indies, and cultivated in various parts of the world, in few countries more largely than in the Middle and Western United States. The flowers appear in July, and the seeds ripen successively in August and September. A decoction or poultice of the leaves is sometimes used as a local galactagogue, and an infusion has been given internally for a similar purpose. (L. L., Dec., 1859.)

1. THE SEEDS.—These are from 8 to 18 mm. long and 4 to 12 mm. broad, oval, compressed, obtuse at the extremities, very smooth and shining, and of a grayish or ash color, marbled with reddish-brown spots and veins. At one end of the seed is a small yellowish caruncle, from which an obscure longitudinal ridge proceeds to the opposite extremity, known as the raphe. In its general appearance the seed is thought to resemble the insect called the tick, the Latin name of which has been adopted as the generic title of the plant. Its variegated color depends upon a very thin pellicle closely investing a hard, brittle, blackish, tasteless, easily separated shell, within which is the kernel, highly oleaginous, of a white color, and of a sweetish taste succeeded by a slight degree of acrimony. The seeds easily become rancid, and are then unfit for the extraction of the oil, which is acrid and irritating. In 100 parts Geiger found, exclusive of moisture, 23.82 parts of envelope, and 69.09 of kernel. These 69.09 parts contained 46.19 of fixed oil, 2.40 of gum, 20.00 of starch and lignin, and 0.50 of albumen. Henry Bower could find no starch, but separated from the seeds an albuminoid principle, which acted with amygdalin and water like emulsin, producing the odor of oil of bitter almond, though in a less degree. (A. J. P., xxvi, 208.) It is highly probable that it is this principle which, acting as an enzyme on the oily matter of the seeds, gives rise to changes in its nature which render them rancid. (See Olea Fixa, p. 810.) G. J. Scattergood found the odor of castor oil to be developed in the beans when bruised with water, and much more powerfully in those long kept than in the fresh. The water distilled from the seeds has a peculiar nauseous odor, quite distinct from that of the oil. (A. J. P., xxvii, 207.)

Taken internally the seeds are powerfully cathartic, and often emetic. Two are sufficient to purge with great violence, and three have produced fatal gastro-enteritis in the adult. After expression of the oil, and treatment with pure alcohol, Calloud found the residue to be powerfully emetic in the quantity of 30 grains, taken in two doses. (J. P. C., 3e ser., xiv, 190.) According to Guibourt, the toxic property pervades the whole kernel, the integuments being inert. The experiments of Scattergood, who found that the water distilled from the seeds is emetic and cathartic, would seem to show that the active principle is volatile, but the researches of Stillmark indicate that it is an enzyme, new, which is a so-called phytalbumose and has been obtained as a white amorphous powder, and is best dissolved in a 10 per cent. salt solution. The aqueous solution of the pure ricin has a neutral reaction. It is a violent poison. E. L. Boerner (A. J. P., 1876, p. 481) obtained butyric acid by macerating the exhausted marc of the seeds with water until decomposed.

2. THE OIL.—This may be extracted from the seeds in three ways: 1, by decoction; 2, by expression; 3, by the agency of alcohol or other solvent.

The process by decoction, which has been practised in the East and West Indies, consists in bruising the seeds, previously deprived of their husk, and then boiling them in water. The oil, rising to the surface, is skimmed or strained off, and afterwards again boiled with a small quantity of water to dissipate the acrid principle. The seeds, it is said, are sometimes roasted, to increase the yield. But by a temperature much above 100° C. (212° F.) the oil is rendered brownish and acrid, and the same result takes place in the second boiling, if care is not taken to suspend the process soon after the water has been evaporated; hence it happens that the West India oil has generally a brownish color, an acrid taste, and irritating properties.

The oil is obtained in this country by expression. The following, we have been informed, are the outlines of the process usually employed by those who prepare it on a large scale. The seeds, having been thoroughly cleansed from the dust and fragments of the capsules with which they are mixed, are conveyed into a shallow iron reservoir, where they are submitted to a gentle heat insufficient to scorch or decompose them, and not greater than can be readily borne by the hand. The object of this step is to render the oil sufficiently liquid for easy expression. The seeds are then introduced into a powerful hydraulic press. A whitish oily liquid is thus obtained, which is transferred to clean iron boilers supplied with a. considerable quantity of water. The mixture is boiled for some time, and, the impurities being skimmed off as they rise to the surface, a clear oil is at length left upon the top of the water, the mucilage and starch having been dissolved by this liquid, and the albumen coagulated by the heat. The latter ingredient forms a whitish layer between the oil and the water. The clear oil is now carefully removed, and the process is completed by boiling with a minute proportion of water, and continuing the application of heat until aqueous vapor ceases to rise, and until a small portion of the liquid, taken out in a vial, continues perfectly transparent when it cools. The effect of this last operation is to clarify the oil, and to render it less irritating by driving off the acrid volatile matter. But much care is requisite not to push the heat too far, as the oil then acquires a brownish hue and an acrid peppery taste. After the completion of the process, the oil is put into barrels and sent into the market. See article on the preparation of castor oil. (A. J. P., 1879, p. 481.) There is reason, however, to believe that much of the American oil is prepared by merely allowing it to stand for some time after expression, and then drawing off the supernatant liquid. One bushel of good seeds yields five or six quarts, or about 25 per cent. of the best oil. If not carefully prepared, it is prone to deposit a sediment upon standing, and the apothecary may find it necessary to filter it through coarse paper before dispensing it. Perhaps this may be owing to the plan just alluded to of purifying the oil by rest and decantation. We have been told that the oil in barrels usually deposits in cold weather a copious whitish sediment, which is redissolved when the temperature rises. A large proportion of the oil consumed in the eastern section of the Union has been derived, by the way of New Orleans, from Illinois and the neighboring States, where it has been at times so abundant that it has been used for burning in lamps and for lubricating machinery.

The process for obtaining castor oil by means of alcohol has been practised in France, but the product is said to become rancid more speedily than that procured in the ordinary mode. Such a preparation has been employed in Italy, and is asserted to be less disagreeable to the taste, and more effective, than the common oil obtained by expression. According to Parola, an ethero-alcoholic extract and an ethereal or alcoholic tincture of the seeds operate in much smaller doses than the oil, and with less disposition to irritate the bowels or to cause vomiting. (See Am. J. M. S., N. S., xiii, 143.)

Owing to the presence of ricin, "castor pomace" or the oil cake obtained by the extraction of castor oil, is unfit for animal food. For the process of removing the poisonous principle see P. J., lxviii, 213.

Italian Castor Oil.—The castor oil plant is cultivated throughout Italy, but especially in the neighborhood of Verona, where the oil is prepared with great care and is remarkably free from the peculiar odor and taste which render this medicine so repulsive to many palates. As it is highly desirable, for certain purposes, that the oil should be as free from these properties as possible, it is a point worthy of investigation, why it is that the Italian oil is superior to most commercial varieties of the oil in these respects. The following facts in relation to the mode of preparing the oil practised at Verona, published by H. Groves, of Florence, acquire on this account a special value. One point of importance is that the seeds are used fresh, as 'the oil rapidly becomes rancid in them when kept. Another fact is that the seeds are entirely deprived of their coating before being submitted to pressure. This is effected by passing them between two revolving wooden rollers, with a winnowing machine beneath, and, to secure the complete absence of integument, they are afterwards assorted by the hand, all being rejected which are not perfectly decorticated. They are then put into hempen bags, which are arranged in layers with a sheet of iron heated to 32.2° C. (90° F.) between them, so as to enable the oil to flow. Lastly, they are submitted to pressure by hydraulic presses. The oil which now flows is of the finest quality. An inferior kind is obtained by pressing the marc at a somewhat higher heat. An interesting and valuable article on the cultivation of the castor bean in the United States appears in the Proc. P. Ph. A., 1916, p. 209, by Joseph L. Lemberger.

Properties.—Pure castor oil is a thick, viscid, colorless liquid, with little odor, and a mild though somewhat nauseous taste, followed by a slight sense of acrimony. As found in commerce it is often tinged with yellow and has an unpleasant odor, and parcels are sometimes, though rarely, met with of a brownish color and hot acrid taste. It does not readily congeal by cold. When exposed to the air it slowly thickens, without becoming opaque. When exposed to the air in a thin layer, it slowly dries to a varnish-like film. It is heavier than most of the other fixed oils. It differs also from most other fixed oils in being soluble in all proportions in cold absolute alcohol. "Castor Oil is a pale yellowish or almost colorless, transparent, viscid liquid, having a faint, mild odor, and a bland, afterwards slightly acrid and generally nauseating taste. It is miscible with dehydrated alcohol or glacial acetic acid. Specific gravity: 0.945 to 0.965 at 25° C. (77° F.). Castor Oil is only partly soluble in petroleum benzin (distinction from most other fixed oils). Castor Oil produces a clear liquid with an equal volume of alcohol (foreign oils). Saponification value: not less than 179 nor more than 185 (see Part III, Test No. 9). Iodine value: not less than 83 nor more than 88." U. S.

Weaker alcohol, of the sp. gr. 0.8425, takes up about three-fifths of its weight. It has been supposed that adulterations with other fixed oils might thus be detected, as the latter are much less soluble in that fluid, but Pereira has shown that castor oil has the property of rendering a portion of other fixed oils soluble in alcohol, so that the test cannot be relied on. (P. J.) ix, 498.) Such adulterations, however, are seldom practised in this country. Castor oil is soluble also in ether, and in its weight of glacial acetic acid. Its proximate composition has been repeatedly investigated. The bulk of it is ricinolein, C3H5(C18H33O3)3, which is the ricinoleic acid (C18H34O3) glyceride. At the same time it also contains a small quantity of tristearin and of the glyceride of dihydroxy-stearic acid, together with from 0.30 to 0.37 per cent. of unsaponifiable matter. Ricinoleic acid, as obtained from the decomposition of the glyceride, is a viscid oil, which solidifies below 0° C. (32° F.), does not solidify in contact with the air by absorption of oxygen, and is not homologous with oleic or linoleic acid, neither of which is found in castor oil. On warming with 1 part of starch and 5 parts of nitric acid (sp. gr. 1.25) castor oil thickens, owing to the formation of ricinelaidin. From this ricinelaidic acid may be obtained in brilliant crystals. Ricinoleic acid is converted by potassium hydroxide into caprylic alcohol and sebacic acid, with disengagement of hydrogen, and the same products are obtained by the reaction of potassium hydroxide with the oil itself. (See J. P. C., Aout, 1885, 113.) Its purgative property is supposed by Bussy and Lecanu to belong essentially to the oil, and not to any distinct principle which it may hold in solution. According to O. Popp, castor oil differs from most other fixed oils in turning the plane of polarized light to the right. (A. J. P., Aug., 1871, 354; from A. Pharm., 1871.) Various substances containing coloring principles, which they yield to castor oil, produce beautiful fluorescence in that fluid when heated with it, such as logwood, turmeric, camwood, etc. (Charles Horner, P. J., Oct., 1874, p. 282.)

Ricinine is a basic substance, C8H8O2N2, which is soluble in all of the ordinary solvents and which occurs as colorless crystals optically inactive and neutral in reaction. It is precipitated from aqueous solutions by Mayor's reagent and Wagner's reagent, showing alkaloidal properties thereby. It is not especially toxic.

Buchheim believes the active principle of castor oil to be ricinoleic acid; this has been confirmed by the experiments of Hans Meyer (A. E. P. P., xxviii, 1890), who finds that both pure ricinoleic acid and the ricinoleate of glyceryl are active purgatives. Ricinelaidic acid, which Buchheim believed to be inactive, Meyer finds when given in fine emulsion to act as powerfully as does castor oil.

By the action of concentrated sulphuric acid upon castor oil is formed a valuable product known as "Turkey-red oil," much used in dyeing and printing with madder and alizarine. The water-soluble portion of this Turkey-red oil is ricinoleo-sulphuric acid, C13H33O.O.HSO3. Turkey-red oil acts as a fixing agent, imparting a superior luster to the fiber dyed with its aid.

Castor oil which is acrid to the taste may sometimes be rendered mild by boiling it with a small proportion of water. If turbid, it should be clarified by filtration through coarse paper. On exposure to the air it is apt to become rancid, and is then unfit for use.

Twombly finds that the best method for removing the odor and taste of castor oil is by washing a cold pressed oil several times with boiling water. After separating, the oil is filtered cold very slowly through a thick layer of powdered animal charcoal. Any effort to quicken the method gives poor results.

Commercially ricin has been employed for the detection of pepsin. For details of the method see Solms. (Z. K. M., 1907.)

Uses.—The cathartic effects of castor oil are due to its ricinoleic acid which is split off in the intestinal tract. This, by gentle irritation of the mucous membrane, excites active peristalsis in the upper bowel and probably also somewhat increases the intestinal secretions, although the main action appears to be due to the increased peristalsis. Because of the thoroughness with which it empties the enteric canal there is on the following day an insufficient accumulation of intestinal contents and hence constipation is liable to follow. Because it cleans out the whole alimentary system and that with relatively small degree of irritation, it is especially valuable in conditions of irritation or inflammation of the bowels, as colic, enteritis, or dysentery; on account of the tendency to subsequent constipation it is not to be recommended as a habitual laxative. It is habitually resorted to in cases of pregnant and puerperal women, and is decidedly, as a rule, the best .and safest cathartic for children. Infants usually require a larger relative dose than adults.

Externally it is useful for its emollient effects in seborrhea and other skin diseases, having the advantage over other oils of being soluble in alcohol.

The dose for an infant is from one to three or four fluidrachms (3.75-11.25-15 mils). It is difficult of administration, from its peculiarly disagreeable taste and from its clamminess and adhesiveness to the mouth. In a few cases, the disgust which it excites is utterly unconquerable by any effort of resolution. A common method of disguising the taste is to give it floating in mint or cinnamon water, but that which we have found, upon the whole, the least offensive is to give it floating on the froth of sarsaparilla syrup mixed with carbonic acid water. Some take it in wine, or spirituous liquors, or the froth of porter, but these are often contra-indicated by their stimulant property. When the stomach is unusually delicate, the oil may be made into an emulsion with mucilage or the yolk of an egg, loaf sugar, and an aromatic water. Tragacanth has been recommended as producing a better emulsion than gum arabic. Tincture of opium may be added in cases of intestinal irritation. A castor oil jelly containing over 90 per cent. of the oil may be made by adding a little stearic acid to the melted oil .and then saponifying with a very small amount of an alcoholic solution of sodium hydroxide. This form a jelly-like preparation which may be sweetened with saccharin and flavored with any desired volatile oil. Castor oil may also be beneficially used as an enema, in the quantity of two or three fluidounces (60 or 90 mils), mixed with some mucilaginous liquid. It has been recommended as a local application to the breasts of nursing women, to promote the secretion of milk.

Though prone to become rancid by itself, it loses much of its susceptibility when mixed with lard, and some druggists are said to use it as a substitute for olive oil in ointments and cerates.

Dose, half a fluidounce to two fluidounces (15-60 mils).

Off. Prep.—Mistura Olei Ricini, Br.; Emulsum Olei Ricini, N. F.; Oleum Ricini Aromaticum, N. F.; Pilulae Antimonii Compositae, N. F.

The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.