Carica Papaya.—Papaw.

Related entry: Asimina.—Papaw

The juice of the fruit, and Papain, the digestive ferment, obtained from Carica Papaya, Linné (Papaya vulgaris, De Candolle).
Nat. Ord.—Passifloraceae.
COMMON NAMES: Papaw, Pawpaw, Mamaeiro.
ILLUSTRATIONS: Botanical Register, Plate 459; Botanical Magazine, 2898 and 2899.

Botanical Source.—Carica Papaya is a tree indigenous to South America, where it is met with in its wild condition, as well as under cultivation, and varies in height, according to its wild or cultivated state, from 5 to 30 feet, and is about 1 foot in diameter (Rees' Cyclopaedia). The trunk or stem is simple, erect, without branches, and gradually tapers from the base to the summit, where it terminates in a cluster of leaves, after the manner of a palm. Its entire length is thickly covered with the scars of the fallen leaves. The leaves are large, alternate, close together, palmately divided into from 5 to 7 irregularly cut lobes, and are borne on leaf-stalks 1 or 2 feet in length, and which are peltately attached. The flowers are dioecious, rarely monoecious, and are grouped at the top of the trunk; the male flowers are borne on long peduncled racemes; the female flowers are solitary and axillary on short stalks, and consist of a small, 5-parted calyx, 5 twisted, pale-yellow petals and a large ovary, bearing 5 dilated, subsessile stigmas. The ovary is globular, 1-celled, and contains numerous ovules attached to 5 parietal placentae. As the ovary enlarges and develops, the leaves gradually fall off, and the fruit, when matured, appears suspended to the highest part of the smooth trunk (L.).

History.—The Carica constitute a family of phanerogamous plants, which grow in the East Indies and in South America, either in a natural state or cultivated. The following species have properties similar to those of C. Papaya: Carica spinosa, Well, a native of the provinces of Pernambuco, Rio do Janeiro, etc.; and Carica dodecaphylla, or jaracatia, a tree of high stature, with a trunk furnished with spines. When incised, this last gives a milky juice. Its fruit is smaller and longer than that of the Carica Papaya.

The Carica Papaya is cultivated throughout the greater part of Brazil, and its fruit bears some resemblance to that of the Cucurbitaceae, especially to the genus Cucumis. The fruit, when ripe, is yellow, irregularly ovoid, with 5 rib-like projections; it is pulpy, enclosing numerous blackish seeds, and has a rather agreeable, sweetish taste. The root is said to have an odor resembling that of rotten cabbage. In Brazil, the common name of the plant is mamaeiro, and the fruit is called mamao. The juice or milk proceeding from the bark or fruit is the part that has attracted attention. In 1850, Hoeferk stated that the juice was milky, bitter, and possessed the property of an irritant poison, and that, when mixed with water, it was used to soften tough meats, by macerating them in the liquid. A. Pinto, A. Camara, and Martius have made nearly the same statements; and Pinto also remarks that it is used to render the skin of the hands soft, and to remove freckles from the face. In 1875, Dr. Roy, an English physician, instituted some experiments with the milky juice, and found that it had the property of softening and dissolving meats; a microscopic examination of the meats thus dissolved showed a complete disintegration of the muscular fibers, the fasciculi being dissociated, and the ultimate fasciculi in a fair way for separation. The entire fluid mass was swarming with vibriones. Other investigators have arrived at the same results.

Chemical Composition.—The milk of mamaeiro, whether from the bark or from the fruit, is so small in amount that a sufficient supply for instituting a regular chemical analysis can not be procured; the greatest quantity that has been obtained from a large number of trees and fruit is in all about 1 fluid ounce. Another circumstance which antagonizes analysis and interferes with investigation of its physiological and therapeutical effects, is the extraordinary rapidity with which it enters into fermentation, and which commences a few seconds after its extraction. The seeds of the fruit contain a resinous acid, which is probably their active principle. Dr. T. Peckolt obtained it by treating the fresh seeds with boiling alcohol and hydrate of lime, and then separating it by means of hydrochloric acid. It forms a yellowish powder, possessing a pungent taste.

The active principle or ferment of Carica Papaya, a true vegetable pepsin, formerly termed caricine, is now known as papain, or papayotin. Mauriac obtained it (from the leaves) by extracting the juice from those recently gathered and filtering it. To the turbid and yellowish-green filtrate, double its volume of absolute alcohol was added, and, gradually, a flocculent precipitate of papain formed upon the filter, slightly greenish and amorphous. This may be purified by new solutions and precipitations, and then carefully drying at a temperature not to exceed 40° C. (104° F.). Papain is obtained from the leaves in the proportion of 4 parts to 100. It is insoluble in alcohol, and perfectly soluble in distilled water. Nitric and hydrochloric acids, bicarbonate of sodium, or of potassium, and caustic potash have no action upon it. It may be employed as a solvent of albuminoid materials in certain forms of dyspepsia, and as an anthelmintic.

PAPAIN is an amorphous powder, white, or yellowish-white, practically odorless when pure, and has a feeble taste, almost imperceptible, Yet faintly suggestive of pepsin. Its composition, further than the fact that it contains 10.6 per cent of nitrogen, has not yet been determined. It dissolves in water and glycerin, the aqueous solution becoming turbid when boiled. Its peptonizing powers are said to be greater than those of pepsin, 0.1 part being capable of dissolving from 100 to 200 parts of moist blood fibrin (see Wurtz, Amer. Jour. Pharm., 1881). It acts under all conditions, whether in neutral, acid, or alkaline media, and is most energetic in the presence of a small amount of fluid. A considerable portion of the papain on the market is said to be practically inert.

In 1890, Dr. Greshoff, in Batavia (Java), discovered a new alkaloid in the leaves of Carica Papaya, which he named carpaine. It exists to the extent of 0.25 per cent in the dried and young leaves, but only in an amount of 0.07 per cent in old leaves; has a bitter taste, and a melting point of 121° C. (249.8° F.). The formula is C14H25NO2, and its physiological properties were investigated by Dr. von Oefele, who found that, with the exception of the caffeine group, carpaine was the only digitalis substitute which, by subcutaneous injection, did not cause local irritation or abscesses, while internal doses of 0.025 Gm. per day did not show any advantage over digitalis (Amer. Jour. Pharm., 1893).

Action, Medical Uses, and Dosage.—Without entering into a description of the varied experiments that have been made with the milk of carica, and concerning which an excellent account is given by Dr. Moncorvo, of Rio de Janeiro, in his translation of an article in the Portuguese language, entitled: "Note on the Physiological and Therapeutical Action of Carica Papaya," by Dr. E. Mauriac, we will simply refer to the conclusions drawn therefrom. This substance exerts a real dissolving or digestive action upon nitrogenized substances; this action is likewise obtained with it in aqueous solution, while its solution in alcohol appears to render it wholly inert. It has no action upon feculent substances. Applied upon the skin, it renders it softer and more smooth, and appears to destroy the projections formed at certain points by a greater or less thickening of the epidermis. Upon the skin deprived of its epidermis, and upon the subcutaneous cellular tissues, it has an extremely irritating action, provoking intense inflammation; and, in addition, the formation of abscesses, rapidly followed by a putrid infection when 30 grains were hypodermatically injected, these symptoms being preceded by severe pain, moaning, and great difficulty of motion. Upon the digestive mucous membrane it acts as a caustic and corrosive substance, its effects being rapid, violent, deep-seated, and occasioning energetic purgation. According to Desjardins, boiling removes these corrosive effects, and it then proves the most active vermifuge of the Materia Medica, in doses of 1 or 2 drachms, mixed with an equal quantity of castor-oil, a single dose being sufficient to cause the expulsion of an astonishing number of the lumbricoids. The seeds possess an identical property, and will probably be found preferable for administration. It is likewise said to cause the destruction and expulsion of the tapeworm. Various preparations of carica, are reputed abortifacient and galactagogue.

The chief property of the milk of the carica is its action upon food, similar to that of pepsin, exercising, like this latter article, a digestive influence upon albuminoid substances. But the difficulty of procuring and preserving a sufficient amount of it for therapeutical use, together with its deeply irritating action, will prevent it from coining into use as a remedy for dyspepsia or gastric affections. To overcome these obstacles, Dr. Mauriac instituted a series of experiments with the leaves of the tree, and found that a concentrated decoction of them exerted upon albuminoid substances an action analogous to that of the milky juice of the tree and of the green fruit, without any appreciable irritation of the gastric mucous membrane. This decoction must be administered in small doses. Dr. Mauriac and others, however, prefer papain, the action of which does not appear to be interfered with by an acid or neutral condition of the stomach, and which, being more energetic than pepsin, must be given in smaller doses, and in aqueous solution. Papain has been used in atonic and fermentative dyspepsia, with painful acid eructations, flatulence, and constipation.

The softening and disintegrating qualities of papain (generally in alkaline combination, as with borax or potassium carbonate), have been taken advantage of in the treatment of warts, corns, sinuses, and chronic forms of scaly eczema, cutaneous tubercles, and other hardness of the skin, produced by irritation, etc., and injected into indolent glandular tumors to promote their absorption. Epithelioma has been similarly treated, but this painful procedure is not to be commended. Glossal fissures and ulcerations, and particularly syphilitic ulcerations of the throat, mouth and tongue, are asserted to have yielded to alkaline solutions of papain. Papain, in 6 per cent solution, when pure, is credited with the power to dissolve the false membranes of diphtheria and membranous croup. This can be accomplished only when the solution can be brought into contact with the membrane by means of brush or spray. It must be frequently applied as it has no power to prevent subsequent formation of the membranous exudate. A 5 per cent solution of papain, with sodium bicarbonate, 5 grains, warmed and instilled into the ear in quantities of 10 or 15 drops, and allowed to remain 1 hour, has given good results in chronic suppurative inflammation of the middle ear, with scanty, offensive discharge; the 5 per cent solution alone has been employed to remove hardened secretions from the auditory canal. The dose of papain is from 1 to 5 grains.

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.