Guaiacum
GUAIACUM, a genus of trees of the natural order Zygophyllaceae. The guaiacum or lignum-vitae tree (Ger. Guajakbaum, Franzosenbaum, Pockenholzbaum; Fr. Gayac, Ga'iac), G. officinale, is a native of the West Indies and the north coast of South America, where it attains a height of 20 to 30 ft. Its branches are numerous, flexuous and knotted; the leaves opposite and pinnate, with caducous (falling early) stipules, and entire, glabrous, obovate or oval leaflets, arranged in 2 or, more rarely, 3 pairs; the flowers are in axillary clusters (cymes), and have 5 oval pubescent sepals, 5 distinct pale-blue petals three times the length of the sepals, 10 stamens, and a 2-celled superior ovary. The fruit is about f in. long, with a leathery pericarp, and contains in each of its two cells a single seed (see fig.). G. sanctum grows in the Bahamas and Cuba, and at Key West in Florida. It is distinguished from G. officinale by its smaller and narrow leaflets, which are in 4 to 5 pairs, by its shorter and glabrous sepals, and 5-celled and s-winged fruit. G. arboreum, the guaiacum tree of Colombia, is found in the valley of the Magdalena up to altitudes 800 metres (2625 ft.) above sea-level, and reaches considerable dimensions. Its wood is of a yellow colour merging into green, and has an almost pulverulent fracture; the flowers are yellow and conspicuous; and the fruit is dry and 4-winged.
The lignum vitae of commerce, so named on account of its high repute as a medicinal agent in past times, when also it was known as lignum sanctum and lignum Indicum, lignum guaycanum, or simply guayacan, is procured from G. officinale, and in smaller amount from G. sanctum. It is exported in large logs or blocks, generally divested of bark, and presents in transverse section very slightly marked concentric rings of growth, and scarcely any traces of pith; with the aid of a magnifying glass the medullary rays are seen to be equidistant and very numerous. The outer wood, the sapwood or alburnum, is of a pale yellow hue, and devoid of resin; the inner, the heartwood or duramen, which is by far the larger proportion, is of a dark greenish-brown, contains in its pores 26% of resin, and has a specific gravity of I '333> and therefore sinks in water on which the alburnum floats. Owing to the diagonal and oblique arrangement of the successive layers of its fibres, the wood cannot be split; and on account of its hardness, density and durability it is much valued for the manufacture of ships' pulleys, rulers, skittle-balls, mallets and other articles.
Chips or turnings of the heartwood of G. officinale (guaiaci lignum) are employed in the preparation of the liquor sarsae compositus concentrates of British pharmacy. They may be recognized by being either yellow of greenish-brown in colour, and by turning bluish-green when treated with nitric acid, or when heated with corrosive sublimate, and green with solution From Bentley & Trimen's Medicinal Plants, by permission of J. & A. Churchill.
Guaiacum or Lignum Vitae, Guaiacum officinale shoot-bearing leaves and flowers, i, Fruit; 2, Vertical section of fruit, showing the solitary pendulous seed in each chamber. All about 5 natural size.
of chloride of lime. They are occasionally adulterated with boxwood shavings. Lignum vitae is imported chiefly from St Domingo, the Bahamas and Jamaica.
The bark was formerly used in medicine; it contains much calcium oxalate, and yields on incineration 23 % of ash. Guaiacum resin, the guaiaci resina of pharmacopoeias, is obtained from the wood as an exudation from natural fissures or from incisions; by heating billets about 3 ft. in length, bored to permit of the outflow of the resin; or by boiling chips and raspings in water to which salt has been added to raise the temperature of ebullition. It occurs in rounded or oval tears, commonly coated with a greyishgreen dust, and supposed to be the produce of G. sanctum, or in large brownish or greenish-brown masses, translucent at the edges; fuses at 85 C. ; is brittle, and has a vitreous fracture, and a slightly balsamic odour, increased by pulverization and by heat; and is at first tasteless when chewed, but produces subsequently a sense of heat in the throat. It is readily soluble in alcohol, ether, chloroform, creosote, oil of cloves and solutions of caustic alkalies; and its solution gives a blue colour with gluten, raw potato parings and the roots of horse-radish, carrot and various other plants. The alcoholic tincture becomes green with sodium hypochlorite, and with nitric acid turns in succession green, blue and brown. With glycerin it gives a clear solution, and with nitrous ether a bluish-green gelatinous mass. It is blued by various oxidizing agents, e.g. ozone, and, as Schonbein discovered, by the juice of certain fungi. The chief constituents are three distinct resins, guaiaconic acid, CigHjoOs (70%), guaiac acid, which is closely allied to benzoic acid, and guaiaretic acid. Like all resins, these are insoluble in water, soluble in alkalies, but precipitated on neutralization of the alkaline solution.
Guaiacum wood was first introduced into Europe by the Spaniards in 1508, and Nicolaus Poll, writing in 1517 (see Luisinus, De morbo gallico, p. 210, Ven., 1566), states that some three thousand persons in Spain had already been restored to health by it. The virtues of the resin, however, were not known until a later period, and in Thomas Paynel's translation (Of the Wood called Guaiacum, etc., p. 9, ed. of 1540) of Ulrich von Hutten's treatise De morbi gallici curatione per administrationem ligni guaiaci (i5!9) we read of the wood: " There foloweth fro it, whan it bourneth a gomme, which we yet knowe not, for what pourpose it serueth." Fliickiger and Hanbury (Pharmacographia, p. 95) state that the first edition of the London Pharmacopoeia in which they find the resin mentioned is that of 1677. The decoction of the wood was administered in gout, the stone, palsy, leprosy, dropsy, epilepsy, and other diseases, but principally in the " morbus gallicus, or syphilis, for which it was reckoned a certain specific, insomuch that at first " the physitions wolde not allowe it, perceyuynge that theyr profile wolde decay therby " (Paynel, op. cit. p. 8). Minute instructions are given in old works as to the mode of administering guaiacum. The patient was confined in a closed and heated chamber, was placed on the lowest possible diet, and, after liberal purgation, was made twice a day to drink a milk-warm decoction of the wood. The use of salt was specially to be avoided. A decoction of I Ib of guaiacum was held to be sufficient for the four first days of the treatment. The earlier opinions as to the efficacy of guaiacum came to be much modified in the course of time, and Dr Pearson (Observations on the Effects of Various Articles of the Mat. Med. in the Cure of Lues Venerea, c. i., 2nd ed., 1807) says: " I never saw one single instance in which the powers of this medicine eradicated the venereal virus." He found its beneficial effects to be most marked in cases of secondary symptoms. Guaiacum resin is given medicinally in doses of 5-15 grains. Its important preparations in the British Pharmacopoeia are the mistura guiaci (dose i-i oz.), the ammoniated tincture of guaiacum (dose J-i drachm), in which the resin is dissolved by means of ammonia, and the trochiscus or lozenge, containing 3 grains of the resin. This lozenge is undoubtedly of value when given early in cases of sore throat, especially of rheumatic origin. Powdered guaiacum is also used.
Guaiacum resin differs pharmacologically from other resins in being less irritant, so that it is absorbed from the bowel and exerts remote stimulant actions, notably upon the skin and kidneys. It affects the bronchi but slightly, since it contains no volatile oil.
The drug is useful both in acute and chronic sore throat, the mixture, according to Sir Lauder Brunton, being more effective than the tincture. The aperient action, which it exerts less markedly than other members of its class, renders it useful in the treatment of chronic constipation. Sir Alfred Garrod has urged the claims of this drug in the treatment of chronic gout. Both in this disease and in other forms of chronic arthritis guaiacum may be given in combination with iodides, which it often enables the patient to tolerate. Guaiacum is not now used in the treatment of syphilis.
The tincture of guaiacum is universally used as a test for the presence of blood, or rather of haemoglobin, the red colouring matter of the blood, in urine or other secretions. This test was first suggested by Dr John Day of Geelong, Australia. A single drop of the tincture should be added to, say, an inch of urine in a test-tube. The resin is at once precipitated, yielding a milky fluid. If " ozonic ether " an ethereal solution of hydrogen peroxide be now poured gently into the test-tube, a deep blue coloration is produced along the line of contact if haemoglobin be present. The reaction is due to the oxidation of the resin by the peroxide of hydrogen such oxidation occurring only if haemoglobin be present to act as an oxygen-carrier.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)
