Manna. U. S. Manna.
Related entry: White ash bark
"The dried saccharine exudation of Fraxinus Ornus Linné (Fam. Oleaceae)." U. S.
Manne, Fr. Cod.; Manna, P. G., It.; Mana, Sp.
Manna is said to be obtained from several other trees besides Fraxinus Ornus, among which F. rotundifolia, F. excelsior, and F. parviflora have been particularly designated. Many saccharine substances, generally exudations from plants, have, from their resemblance to this substance, obtained the name of manna, and attracted more or less attention from writers. The term "manna" has been applied to certain substances which have no relation to true manna, notably to the lichen Lecanora esculenta, which at times has suddenly fallen like rain over immense tracts of country, from Persia to the African Sahara. It occurs in the form of small roundish lumps, from the size of a pin's head to that of a pea, yellowish or grayish externally and whitish within, hard, inodorous, and insipid. It has been affirmed that this lichen does not contain starch, but it is really used as an article of food, and good bread is said to have been made out of it. (Nature, Jan., 1891.) It is probable that it is the manna of Scripture.
The proper false mannas, exudations from various trees, are best considered under the headings of the countries which yield them:
European False Manna, or Briancon Manna, an exudation from the common European larch (Larix europaea, or Pinus Larix), differs chemically from ordinary manna in containing no mannite. Berthelot found in it a peculiar sugar, which he named melezitose. (See A. J. P., 1859, p. 61.) To this the formula C18H32O16+2H20 is given showing that it belongs to the class of the saccharides.
American False Manna.—A substance resembling manna, of a sweet, slightly bitter and terebinthinate taste, and actively purgative, exudes from incisions in Pinus lambertiana, of Oregon, and was used by the natives. Berthelot has extracted from this product a peculiar saccharine principle, which he calls pinite. It is very sweet, but does not undergo the vinous fermentation. (See A. J. P., xxviii, 157.) Pinite was for a long time classed among the sugars, but the latest researches seem to show that it is a hexahydric phenol derived from hexahydro-benzene. The formula is C17H14O6, and it is a methyl derivative of inosite.
California Manna, or Father Picolo's Manna.—Proust (Ann. d. Chim., 1806, 145) alludes to a manna mentioned by Father Picolo as being deposited on a species of grass in California. J. U. Lloyd (A. J. P., 1897, 337) believes Picolo's manna to be a saccharine deposit, caused by aphides on Phragmites communis. It is apparently still collected by the Indians.
African False Mannas.—Turkish Manna is a sweet product obtained from Echinops persica Fisch., and is obtained by treating the cocoons of a coleopterous insect (Larinus maculatus) with hot water, filtering and crystallizing the sugar. From it Berthelot obtained a new variety of sugar, trehalose, C12H22O11+2H2O. (Gaz. Med. de Paris, 1857.) Pinus Cedrus, of Mount Lebanon, yields a similar product, which has some repute in Syria as a remedy in phthisis. (P. J., xiii, 411.) In the neighborhood of Diarbekir, in Asiatic Turkey, a saccharine substance, known as Diarbekir manna, is found on the leaves of dwarf oaks, from which it appears to be exuded. (P. J., Nov., 1862, p. 546.) The manna of the oak of Kurdistan, spoken of by Flückiger, is probably the same as that of Diarbekir, which may be its entrepot. According to Flückiger, this consists chiefly (90 per cent.) of a crystallizable sugar. It deviates to the right the plane of polarized light, and reduces in the cold the solution of copper oxide in soda and glycerin. This manna contains a mucilage, but no cane sugar or dextrin. (J. P. C., April, 1873, p. 335.) Quercus Vallonea Kotschy, and Q. persica Jaub. et Spach, yield "oak manna," through insect agency, while certain species of Echinops (probably E. persica Fisch.. yield the singular manna-like substance that is known as Trehala in Syria, and as Shukkar Tigal in India. Pyrus glabra yields a manna which is collected by the people of Luristan, in Persia. It has long been known that Salix fragilis and probably other species of willow yield to the Persians a manna-like exudation. According to Raby (L'Union Pharm., May, 1889), there are two varieties, chirkhest and bidenguebin, which contain respectively, according to the analysis of Ludwig, chirkhestite (C6H14O6), allied to sorbite, and bidenguebinose (C12H22O11), allied to melezitose. "Whether these mannas are really distinct from those sold in the Indian bazaars as coming from Afghanistan and Persia seems uncertain. Of these bazaar mannas the most important is the Shirkoit or Oriental manna. By Haussknecht it is referred to Atraphaxis spinosa;but J. E. T. Atchison states that it is yielded by the Cotoneaster nummularia Fisch. et Mey., a tall, stout shrub, whose smaller branches in July become covered with an exudation, which is eaten as a sweetmeat, and exported in quantity to Russia and India. The second variety, Taranjabin, is yielded by the camelthorn, Alhagi Camelorum Fisch., in Persia and Afghanistan, and probably by Alhagi Maurorum of De Candolle, a leguminous thorny shrub abundant in India—if indeed the two species be distinct. According to A. Villiers, it is nearly pure melezitose. (P. J., 1876, 3d ser., vii, 917.) Another kind of manna is Gazangabin, or Gazanjabin, yielded by Tamarix gallica Linn., var. mannifera;a fourth kind is obtained from the Salsola foetida DC. (P. J., Dec. 11, 1886, 467.) The tamarisk of Northern Africa (Tamarix gallica Ehr.., which produces the small tamarisk galls of Mogador, containing 40 per cent. of tannic acid (A. J. P., 1878, p. 27; also N. R., 1877, p. 41), according to Burckhardt also gives origin to a species of manna that is used by the Bedouin Arabs near Mount Sinai with their food. This substance, however, according to Mitscherlich, contains no mannite, but consists wholly of mucilaginous sugar. Berthelot found a manna from Sinai to consist of 55 per cent. of cane sugar, 25 of levulose and glucose, and 20 of dextrin and analogous substances. (Ann. Ch. Phys., lxvii.)
Persian Manna, or Gez, has been identified (C. D., 1894, 790) as being derived from Astragalus anisacanthus, and is found in the districts of Khonsar, Feridan and Chahar Mahal, and Ispahan. In the form of sweetmeat, having the appearance of flour, it is sent all over Persia and much esteemed.
Australian Mannas.—A manna-like exudation on the Eucalyptus viminalis Labill., growing in New South Wales, contains a saccharine matter called melitose, different in properties from mannite and from all the varieties of sugar, though isomeric with glucose. It is susceptible of the vinous fermentation. (See A. J. P., xxviii, 157.) Lerp is produced upon the leaves of Eucalyptus dumosa, when very small, and sometimes appears spread over large extents of country like a kind of snow. The natives use it for food. It is a complex body, containing an unfermentable sugar, eucalin, gum, starch, inulin, and lignin. (J. P. C., xvi, 240.) It is said to be a secretion from an insect, formed into minute cells, each of which is the abode of one of the insects. (See A. J. P., 1862, p. 547.) Myoporum platycarpum R. Br. , the sandalwood or dogwood-tree of Australia, exudes an exceedingly sweet and pleasant manna, which is much used as an article of food. The product is identical with the official manna, containing nearly 90 per cent. of mannite. F. W. Passmore obtained from Eucalyptus Gunnii Hook., a sugar termed melitriose. (P. J., 1891, 718.)
New South Wales Manna.—According to R. T. Baker (Journ. and Proc. Boy. Soc. New South Wales, xxx, 1897), this manna is produced in the form of nodules at the nodes of the stems of the blue grass Andropogon annulatus. It contains numerous crystals of mannite, amounting, according to the analysis of H. G. Smith, to 50 per cent.
Fraxinus Ornus, or the European flowering ash is a tree of moderate height, usually from twenty to twenty-five feet, very branching, with opposite, petiolate, pinnate leaves, composed of three, or four pairs of leaflets, and an odd one at the. end. The leaflets are oval, acuminate, obtusely serrate, about an inch and a half in length, smooth, of a bright green color, and supported on short footstalks. The flowers are white, and usually expand with the leaves. They grow in close panicles at the extremities of the young branches, and have a very short calyx with four teeth, and four linear-lanceolate petals.
Fraxinus Ornus is native of Sicily, Calabria, and Apulia, and is cultivated in Sicily. It yields manna after the eighth year, and continues to yield it for ten or twelve years, when it is usually cut down and young sprouts are allowed to grow up from the root. (Stettner, A. Pharm., liii, 194.) During the hot months the juice exudes spontaneously from the bark, and concretes upon its surface, but, as the exudation is slow, it is customary to facilitate the process by making deep longitudinal incisions on one side of the trunk. In the following season these are repeated on the other side, and thus alternately for the whole period during which the tree yields manna, extending sometimes, it is said, to thirty or even forty years. Straw or chips are frequently placed so as to receive the juice, which concretes upon them. The manna varies in its character according to the mode of collection, the nature of the season, and the period of the year at which the exudation takes place. That procured in Sicily is said to be the best. Daniel Hanbury travelled through the old manna region, and satisfied himself that the collection of manna for commercial purposes is confined almost exclusively to Sicily. (P. J., Nov., 1872, 421.) For information on manna collection in Sicily, see notes by J. S. Ward. (P. J., 1893, 381;) For an interesting description of California mannas by J. U. Lloyd, particularly Picolo's manna, see A. J. P., 1897, 329.
In commerce three varieties are distinguishable :
1. FLAKE MANNA, or manna canulata (cannellata), is the purest variety, and is chiefly obtained from Palmero. It exudes spontaneously, or from incisions, during the hottest and dry-est weather in July and August. According to Stettner, it is furnished by the upper incisions upon the trunk, while the lower incisions yield the inferior varieties. It is in irregular, unequal pieces, often several inches' long, resembling stalactites, rough, light, porous, brittle, whitish or yellowish-white, and frequently concave on the surface by which they were attached to the trunk, and which is often soiled by impurities, sometimes by adherent fragments of the bark. When broken, these pieces exhibit a crystalline or granular structure. This variety is sometimes in small fragments, generally less than an inch in length.
2. COMMON MANNA—manna communis, or the manne en sorte of French pharmacy—is next in quality, and is collected in Sicily in September and the beginning of October, when the heat of the weather has begun to moderate. The juice does not now concrete so readily, and a portion, falling on the ground at the root of the tree, becomes more or less mixed with impurities, and forms imperfectly solid masses, which require to be further dried in the sun. Common manna consists of whitish or yellowish fragments, similar to the pieces of flake manna, but much smaller, mixed with a soft, viscid, uncrystallized brownish matter, identical with fat manna.
3. FAT MANNA, or Manna (pinguis) sordida, is collected in the latter part of October and November, when the weather is cooler and rains are more common. The juice is now still less disposed to concrete, and flowing down the trunk is received in a small excavation at its base. As found in commerce, it is in the form of a soft, viscous mass, containing few crystalline fragments, of a brown or yellowish-brown color, and full of impurities. The U. S. Pharmacopoeia directs that such manna should be rejected.
Fictitious Manna.—Attempts have been made to counterfeit manna, but the facility of detection renders such frauds unprofitable, and they are not often practised. R. P. Thomas described (A.J.P., xxiv) a sophisticated manna which differed from the genuine drug both in sensible and in chemical properties, not even containing mannite. Baume describes a method in which common manna is purified so as to resemble flake manna. It consists in dissolving common manna in a little water, allowing the liquid to settle, decanting it in order to separate the impurities, then inspissating it so that it will congeal on cooling, and immersing threads in the inspissated liquid, several times successively, in the manner practised by candle makers. It may be still further purified by the use of animal charcoal. Thus prepared, it contains less mannite than flake manna, and less of the nauseous principle, but is said not to operate less effectively as a laxative. A fictitious manna is described by Edmond Histed (P. J., April, 1870) as having been taken from Paris to London, which bears a close resemblance to flake manna, for which it might be mistaken upon a hasty notice. The resemblance was, moreover, increased by the fact that it contains mannite, of which Histed obtained 40 per cent., while fine natural flake manna yielded him 70 per cent. Closely examined, it is found to differ essentially from genuine flake manna, showing no crystals of mannite when broken, not having the taste and smell characteristic of good manna, and, besides, being cleaner, lighter-colored, more solid, and making a clearer solution in water. (See A. J. P., 1870.) This may have been a specimen of artificial flake manna, prepared from the inferior or common manna.
Properties.—Manna is officially described as "an irregular, more or less elongated, flattened, 3-sided pieces; externally yellowish-white; friable, somewhat waxy; internally nearly white, porous and crystalline in appearance; odor slight, but characteristic; taste sweet, slightly Bitter and faintly acrid. Manna also occurs in irregular masses, consisting in part of brittle or soft, resin-like fragments; from yellowish-white to yellowish-gray in color. The quantity of the yellowish-white fragments must not be less than 40 per cent. of the whole. Add 5 Gm. of Manna. to 100 mils of alcohol, heat to boiling and filter; on cooling, the filtrate rapidly deposits crystals of mannite." U. S.
Manna has a slight, peculiar odor, and a sweet taste, which in the impure kinds is also very nauseous, but in the finest flake manna scarcely so much so as to be disagreeable. Its sp. gr. is 0.834. It melts with heat, and takes fire, burning with a blue flame. When pure it is soluble in three parts of cold and in its own weight of boiling water. From a boiling saturated aqueous solution it separates in partially crystalline masses on cooling. Alcohol also dissolves it. Boiling alcohol will dissolve 15 parts of manna, and upon cooling deposit beautiful crystals of mannite.
Ebert (Zeit. Oest. Apoth. Ver., xlvi, p. 427) has contributed a very able paper, containing citations of all the literature up to 1908, regarding the origin and pharmacognosy of the different varieties of manna. Probably the most comprehensive monograph on the ash manna is that of Tschirch in his large work entitled "Handbuch der Pharmakognosie." Band II, p. 103.
Fourcroy and Vauquelin found manna to consist of (1) a peculiar sweet principle, mannite, which constitutes 75 per cent.; (2) a variety of sugar; (3) a yellow nauseous matter, upon which the purgative property is thought chiefly to depend; and (4) a little mucilage. Leuchtweiss obtained from 105 parts of manna, 11.6 o£ water, 0.4 of insoluble matter, 9.1 of sugar, 42.6 of mannite, 40.0 of a mixture of mucilaginous matter containing mannite, resin, organic acid, and a nitrogenous substance, and 1.3 of ashes. In manna canellata in fragmentis he found 37.6 per cent. of mannite, and in manna Calabrina 32 per cent. (Pflanzenstoffe, 2d ed., p. 180.) Buignet discovered in manna a considerable proportion of dextrin. He appears to have been led to this discovery by observing a very energetic dextrogyrate power in flake manna, which could not be owing to the saccharine matter it contained, because the same power continued after all the sugar had been destroyed by fermentation. Dextrin forms about one-fifth part of flake manna, and a much larger part of the inferior kinds. Tanret (Bul. Soc. Ch., 1902, p. 947) finds manna to contain several new carbohydrates and reports the composition as follows: mannitol, 40 to 55 per cent.; levulose, 2.5 to 3.4 per cent.; dextrose, 2.2 to 3.0 per cent.; manneotetrose (C24H42O21 + 4HsO), 12 to 16 per cent.; manneotriose (C18H32O16), 6 to 16 per cent., with small amounts of resin and ash.
Fluckiger found in all samples of mannite examined a small amount of a dextrogyrate mucilage, which is precipitated by neutral lead acetate, and yields mucic acid when boiled with strong nitric acid. The greenish color of certain pieces of manna is produced by fraxin, C16H18O10, a glucoside closely resembling aesculin. Fraxin crystallizes in colorless prisms, easily soluble in hot water and in alcohol, and has a faintly astringent and bitter taste. By diluted acids it is resolved into fraxetin, C10H8O5. and glucose, C6H12O6. Even its diluted solutions are fluorescent. (Pharmacographia, 2d ed.)
Mannite (mannitol) is white, inodorous, crystallizable in semi-transparent needles, of a sweetish taste, soluble in five parts of cold water, scarcely soluble in cold alcohol, but readily dissolved by that liquid when hot, and deposited when it cools. Its composition is C6H14O6, and it is considered as belonging to the class of hexatomic alcohols. If mixed with chalk and cream-cheese and kept for some weeks at the temperature of 40° C. (104° F.), it yields alcohol largely, with the disengagement of carbonic acid and hydrogen and the production of lactic acid. No fungus is produced, as in the ordinary fermentation of sugar. (Berthelot, J. P. C., xxx.) With lime, barium and strontium oxides, it forms definite compounds, soluble in water, and precipitable from their aqueous solutions by alcohol. (Ibid., Jan., 1860.) It does not reduce an alkaline solution of copper oxide; and a test of its purity is thus presented. (A. J. P., Jan., 1861, p. 26.) It is optically inactive except after the addition of borax. It is then found to be dextrorotatory. Emil Fischer has shown that there are three mannites obtainable; the ordinary mannite is the dextrorotatory variety, and is always obtained in the reduction of a-mannose with sodium amalgam; a laevorotatory variety is obtained by the reduction of l-mannose; and an inactive mannite is obtained from the inactive mannose. These three physical isomers differ slightly in their fusing points and crystalline form. The native variety may be obtained by boiling manna in alcohol, allowing the solution to cool, and redissolving the crystalline precipitate; pure mannite is now deposited. Another method is to dissolve flake manna in water, precipitate by solution of lead subacetate, filter, throw down the excess of lead by sulphuric acid, evaporate the solution, and mix with alcohol. On cooling", the mannite is deposited. (Bonsall, A. Pharm., cxxxiv, 70.) This principle has been found in numerous vegetables. It is said to be gently laxative in the dose of from one to two ounces (31-62 Gm.).
Manna, when long kept, acquires a deeper color, softens, and ultimately deliquesces into a liquid, which on the addition of yeast, undergoes the vinous fermentation. This is probably owing to its conversion into sugar by the absorption of enough oxygen to cause it to pass over into some variety of glucose or fermentable sugar. That which is driest resists this change the longest. It is said that manna recently gathered is less purgative than it afterwards becomes.
Uses.—Manna is a gentle laxative, usually operating mildly, but in some cases producing flatulence and pain. It is usually prescribed with other purgatives, particularly senna, rhubarb, magnesia, and the neutral salts, the taste of which it conceals, while it adds to the purgative effect. It is usually given dissolved in water or some aromatic infusion; but the best flake manna may be administered in substance. Manna forms a combination with iron, which it preserves against oxidation. (See P. J., March, 1873.) Under the name of dulcinol a mixture of mannite and common salt has been recommended by Sternberg (D. M. W., 1906, p. 1707) as a sweetening agent in diabetes.
Dose, half to one ounce (15.5-31 Gm.).
Off. Prep.—Infusum Sennae Compositum, U. S.; Syrupus Mannae, N. F.