Hyoscyamus
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Hyoscyamus is a small genus of plants containing eleven species known generally as the henbanes.
Selected species:
- Hyoscyamus albus - white henbane
- Hyoscyamus aureus - Golden henbane
- Hyoscyamus muticus - Egyptian henbane
- Hyoscyamus niger - black henbane
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Botanical Source.—Henbane is a biennial plant, with a long, spindle-shaped, thick and corrugated root, of an internal, whitish color, and externally brown. The stem is from 6 inches to 2 feet high, erect, tapering scarcely branched, and covered closely with long, weak hairs, tipped with a minute black gland. The leaves are large, oblong, acute, alternate, coarsely and unequally sinuated, occasionally somewhat decurrent, stem-clasping at the base, pale dull-green, and slightly pubescent, with long, glandular hairs upon the midrib. The flowers are numerous, axillary, subsolitary, nearly sessile, and embosomed in the uppermost leaves, than which they are much shorter. The corolla is of a dull, dirty yellow, strongly netted with purple veins, deep-purple at the orifice, funnel-shaped, with a somewhat erect, 5-lobed limb; lobes rounded, spreading, the 2 anterior a little smaller than the others, and separated at base by a deep slit in the tube. Calyx villous, funnel-shaped, 5-lobed, regular, wider than the corolla, to whose tube it is equal in length and persistent; each lobe is ovate and acute, with an open aestivation. Stamens 5, declinate, straight, shorter than the corolla, the 3 lower longer than the others; filaments pubescent, inserted about the middle of the tube of the corolla, and inclined; anthers cordate and purple. The ovary is nearly round, shining, pale-green, 2-celled, with numerous ovules, adhering to the dissepiment; style filiform, declinate, and purple at the apex; stigma blunt, round, and capitate. The fruit is an ovate, 2-celled capsule, opening transversely by a convex lid. The seeds are many, small, obovate, and brownish (L.—B.). The whole plant has a disagreeable, fetid odor, and a repulsive appearance.
History.—Henbane is an European herb, naturalized in this country, growing in waste grounds and commons, and flowering from June to September. Botanists are divided as to whether it is an annual or biennial plant. All parts of the plant are medicinal, but the leaves and seeds are the parts usually employed; the former should be collected at the time of its flowering, and the latter when perfectly matured. The leaves of the second year's growth of the plant are reputed more active than those of the first year; when fresh they abound in a viscid juice, and when bruised have a nauseously rank, narcotic smell, and an acrid, oleaginous, disagreeable taste. Upon drying, the smell and taste are almost destroyed. The leaves impart their properties to diluted alcohol; water, alcohol, ether, fixed or volatile oils also take up a portion of their virtues. The aqueous infusion is tasteless, light-yellow, and has the taste and odor of the plant. The leaves should be kept in a dry situation on account of their tendency to absorb moisture.
Chemical Composition.—According to Morries, an empyreumatic and highly poisonous oil is obtainable by the destructive distillation of henbane (Edin. Med. and Surg. Jour., Vol. XXXIX, p. 379), The chief constituents of hyoscyamus seeds, besides fixed oil and fatty matter, gum, starch, albuminous matter, etc., are two alkaloids, hyoscyamine and hyoscine, the latter having been recognized, in 1880, by Ladenburg (Lieb. Ann., Vol. CCVI, p. 279), and previously (1876) observed by Buchheim, and called by him sikeranine. Mr. F. Mahla obtained nearly 2 per cent of nitrate of potassium from the leaves of henbane (Amer. Jour. Pharm., 1859, p. 402).
HYOSCYAMINE (C17H23NO3, Ladenburg), was found in henbane (impure) by Peschier (1821) and by Payen (1824), and subsequently purified by Geiger and Hesse (1833). It is more abundant in the seeds than in the herb, the latter when fresh, yielding 0.14 to 0.16 per cent; in the fresh seeds Wadgymar (Proc. Amer. Pharm. Assoc., 1867, p. 404), found as high as 0.52 per cent of the alkaloid. (For a summary review of the various methods pursued in isolating hyoscyamine, see Husemann and Hilger, Pflanzenstoffe, 1181.) In purest form it is obtainable from its (purified) gold double chloride (Ladenburg). Pure hyoscyamine crystallizes in tufts or stellate, silky needles of an acrid, unpleasant taste; when impure it is an amorphous, deliquescent mass, having a nauseating, narcotic, tobacco-like smell. It dissolves sparingly in cold, more readily in hot water, is soluble in alcohol, ether, chloroform, benzol, and amyl alcohol. Its melting point is 108.5° C. (227.3° F.). Hyoscyamine is strongly basic and forms crystallizable salts with acids. In aqueous solution it is very unstable, being decomposed by heat, especially when heated with alkalies, ammonia then being liberated. Ladenburg proved it to be an isomer of atropine (which see), yielding the same decomposition products (tropine and tropic acid) as atropine when heated with diluted hydrochloric acid or baryta water. From solutions of its salts, hyoscyamine is but incompletely precipitated by caustic alkalies or carbonates; it forms precipitates with auric chloride, tincture of iodine, tannic acid, and other alkaloidal reagents. The platinic double chloride is more soluble than that of atropine. This behavior permits its isolation from commercial (impure) atropine. Hyoscyamine is identical with duboisine from Duboisia myoporoides (Ladenburg), and is likewise identical with daturine (see Merck's Index, 1896). Hyoscyamine is an active poison, as are its salts; a minute quantity of it placed within the eye, causes a persistent dilatation of the pupil.
Hyoscine (C17H21NO4, O. Hesse and E. Schmidt). This base was obtained by Ladenburg from commercial semi-liquid brown hyoscyamine by dissolving it in water, precipitating with gold chloride, and recrystallizing from hot water, from which solution hyoscine gold chloride first precipitates, and the base is then easily regenerated. Hyoscine forms an amorphous, semi-liquid mass, not easily soluble in water, easily soluble in alcohol and ether. It yields crystallizable salts with acids, and on warming with baryta water at a temperature of 60° C. (140° F.), is decomposed into tropic acid (C9H10O3), and pseudo-tropine (C8H15NO). A water soluble hyoscine was recently found by O. Hesse to be obtainable in comparatively large quantities from the flowers of Datura alba, an ornamental plant cultivated in southern Germany (Druggists' Circular, 1899, p. 85).
Action, Medical Uses, and Dosage.—Hyoscyamus is a powerful narcotic, and is dangerously poisonous, though fatalities from it or its alkaloids are rare. In fact, the physiological action of henbane and its bases scarcely differs from that of stramonium and belladonna and their alkaloids, except in degree. It produces the same dryness of the mouth, flushing of the face, pupillary dilatation, quickened cardiac and respiratory action, illusions, hallucinations, and delirium occasioned by belladonna, only in a lesser degree. No difference is observable in the action of hyoscyamine and atropine upon the mechanism of accommodation and upon the movements of the lungs and heart. Hyoscyamine is more hypnotic and less apt to cause delirium than atropine. The dilatation of the pupils, which, however, does not always take place under hyoscyamine, is caused by stimulation of the sympathetic nerves. When death occurs from hyoscyamus or its alkaloids it is due to respiratory paralysis. The alkaloids are eliminated by the kidneys. In large doses, but insufficient to produce death, the tendency of hyoscyamus is to produce general paralysis of the nervous structures. One patient lost her memory from being poisoned with it. Among the ill effects of hyoscyamus are: Deranged vision, dilatation of the pupils, giddiness, general excitation, fullness of pulse, flushing of the face, weight in the head, headache, loss of muscular control, with tremulousness, mental confusion, incoherency or loss of speech, somnolency, furious delirium, unconsciousness, coma, irresponsiveness of the pupils to light, cold sweat, small, frequent, and feeble pulse, and deep and labored respiration. Tetanic rigidity may be present a portion of the time and sometimes convulsions, as well as nausea, vomiting, and intestinal pain and purging. The treatment of poisoning by hyoscyamus is that indicated under Belladonna. Chloral is especially recommended for poisoning by hyoscine. Autopsies reveal gastro-intestinal inflammation from poisoning by this drug.
When 1/15 of a grain of sulphate of hyoscyamine has been subcutaneously injected hyoscyamine has been detected in the urine 22 minutes afterward. If enough be injected to cause complete dryness of the tongue and hard and soft palates, the pulse will increase temporarily in frequency, volume, and power; if this effect upon the tongue is not produced, the pulse will be lessened in frequency without diminution of its volume and force, and giddiness, somnolency, and dilatation of the pupils will accompany, the patient frequently acting as if intoxicated (Harley). (Compare Atropinae Sulphas and Duboisia.)
