Menyanthes. Buckbean, Marsh Trefoil, Water Shamrock. Menyanthes trifoliata.
Menyanthes. N. F. IV. Buckbean. Marsh Trefoil. Bogebean. Water Shamrock. Folia Trifolii Fibrini.—" The dried leaves of Menyanthes trifoliata Linné (Fam. Gentianaceae)." It is an ingredient in Vinum Aurantii Compositum, N. F. IV. This gentianaceous plant is a native both of Europe and North America, from Greenland to Alaska and south to Pennsylvania, Minnesota, and California. All parts of menyanthes are efficacious, but only the leaves are official.
It is described by the N. F. as "glabrous; petioles from 10 to 15 cm. in length, stout but soft and weak, the base more or less sheathed with broad, thin, and membranaceous, somewhat translucent stipules; blade ash-green, trifoliate; leaflets, sessile or very short-petioled from 5 to 8 cm. in length and usually about two-thirds as broad, obovate, blunt, entire or occasionally coarsely and unequally crenate. Odor slight but characteristic; taste decidedly bitter. Menyanthes yields not more than 10 per cent. of ash." N. F. Its virtues depend on a bitter principle denominated menyanthin, which may be obtained sufficiently pure for use by treating the spirituous extract of the plant with hydrated lead oxide, removing the lead by hydrosulphuric acid, filtering and evaporating the liquor, exhausting the residue with alcohol, and again evaporating with a gentle heat. It has a bitter taste, is soluble in alcohol and water, but not in pure ether, and is chemically neutral. Kromayer (1865) assigned to it the formula C30H46O14, and stated that it breaks up on heating with diluted sulphuric acid into a fermentable sugar and menyanthol, a colorless, difficultly volatilizable oil, with an odor like that of bitter almond. K. Leuderich (A. Pharm., 1892, 38 and 48) has studied menyanthin, and gives it the formula C33H50O14, and states that its decomposition products are a phenol-like body, menyanthol, C7H11O2, a resinous product, and a left-rotatory sugar.
Vridevel (P. J., 1910, lxxxv, p. 465) has separated a second glucoside from menyanthes, to which he gives the name of meliatin. It is a crystalline body, with a melting point of 217° C. (422.6° F.).
With the ordinary properties of the bitter tonics, menyanthes unites a cathartic power; in large doses it may cause vomiting. The dose of the powdered leaves or root as a tonic is from twenty to thirty grains (1.3-2.0 Gm.); of an infusion, prepared with half an ounce to a pint of boiling water, from one to two fluidounces (30-60 mils); and of the extract, ten or fifteen grains (0.65-1.0 Gm.), to be repeated three or four times a day. A drachm of the powder, or four fluidounces of the strong decoction, generally purges, and often occasions vomiting.