Related entries: Piscidia.—Jamaica Dogwood
The root and stem of Franciscea uniflora, Pohl (Brunfelsia Hopeana, Bentham).
COMMON NAMES: Mercurio-vegetal, Manaca, Manacán, Camganiba, Geratacáca.
Botanical Source.—This shrub is much branched, and is extremely variable as regards the shape of the leaves presenting obovate, oblong, obtuse, or acute ones on the same branch. The leaves are alternate, from 1 to 3 inches long, narrowing at the base, smooth, and, in texture, intermediate between coriaceous and membranaceous. The flowers are usually solitary, white, blue, or violet, and terminal on the smaller branches. Stamens 4, and ovary 2-celled, and surrounded by a fleshy ring. Stigma is coated with a glutinous, green, fungoid substance, serving to retain the pollen (DeC.).
History and Description.—This plant is occasionally cultivated in greenhouses. It is a native of the American equatorial sections. Two kinds of manaca are found in commerce (white and red), being undoubtedly of different botanical origin. Jamaica dogwood (Piscidia Erythrina. is known in some sections of South America under the name manaca. The leaves are sometimes employed medicinally as well as the root and stems. As found in commerce, the drug consists of both stem and root, in pieces ranging from 1/4 to 1 inch in thickness, and 6 to 8 inches in length. The wood is hard, tough, and yellowish-red in color, and surrounds a narrow pith; the bark, which closely adheres to the wood, is deep-brown in color and smooth when young, but in the older species the bark is rust-brown, rough, and scaly. It has a bitter taste, but no odor. Fluid extract of manaca, was introduced to the American medical profession through the efforts of Parke, Davis & Co.
Chemical Composition.—The drug was analyzed by R. Lenardson, of Dorpat, 1884, who found the bark and the wood of root and stem to contain two proximate principles, one a weak, amorphous alkaloid of bitter taste, which (previously indicated by Prof Dragendorff) he called manacine; the other fluorescent body is most probably identical with gelsemic acid. Manacine is toxic in large doses, soluble in water and alcohol, but insoluble in ether and chloroform. Its solutions are prone to decomposition, a brownish resin being formed. Brandl, in 1895, found that manacine decomposes in the presence of water at higher temperatures, a new compound, manacëine, and a resinous and fluorescent substance resulting, the latter being identical with aesculetin (Jahresb. der Pharm.). A complete analysis of the drug, by John L. Erwin, is reported in the Pharmacology of the Newer Materia Medica, 1892, published under the auspices of Parke, Davis & Co.
Action, Medical Uses, and Dosage.—This agent was introduced as a remedy for rheumatism, the decoction having been so employed by the people living in the region of the Amazon. It was also reputed to be a remedy for syphilitic complaints, hence its name, vegetable mercury. Manaca has an influence over the nervous structures and the glands, being particularly diuretic. Painful sensations in the back and head are said to be the first effects of the decoction, which sensations are followed by profuse diaphoresis. Moderate doses induce emesis and purgation, greenish stools being passed. Gastro-intestinal effects from large doses may produce death, while its immoderate employment during pregnancy has occasioned abortion. Undoubtedly the agent acts in rheumatic complaints much like mezereum, guaiac, etc. It may be given in the subacute forms of rheumatism affecting the muscles and tendons, but is of little or no value in that form affecting the joints. Dull, heavy pains and soft skin, without fever, seem to be the symptoms indicating it. The dose of the fluid extract of manaca is from 10 to 60 minims.
King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.