Hyoscyamus

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Chapter: Pharmacognosy and Phytochemistry : Drugs Containing Alkaloids

Hyoscyamus consists of the dried leaves and flowering tops of Hyoscyamus niger Linn., belonging to family Solanaceae. It contains not less than 0.05% alkaloids, calculated as hyoscyamine.


HYOSCYAMUS

 

 

Synonyms

 

Common Henbane, Hyoscyamus, Hog’s-bean, Jupiter’s-bean, Symphonica, Cassilata, Cassilago, Deus Caballinus.

 

Biological Source

 

Hyoscyamus consists of the dried leaves and flowering tops of Hyoscyamus niger Linn., belonging to family Solanaceae. It contains not less than 0.05% alkaloids, calculated as hyoscyamine.

 

Geographical Source

 

It is found throughout Central and Southern Europe and in Western Asia, extending to India and Siberia. As a weed of cultivation it now grows also in North America and Brazil. Apart from these countries, it grows in Scotland, England and Wales and also in Ireland, and has been found wild in 60 British countries.

 

History

 

The medicinal uses of Henbane date from Ancients times, being particularly commended by Dioscorides (first century A.D.), who used it to procure sleep and allay pains, and Celsus (same period) and others made use of it for the same purpose, internally and externally. This use is mentioned in a work by Benedictus Crispus (A.D. 681) under the names of Hyoscyamus and Symphonica. There is frequent mention made of it in Anglo Saxon works on medicine of the eleventh century, in which it is named ‘Henbell’, and in the old glossaries of those days it also appears as Caniculata, Cassilago and Deus Caballinus

 

Later it was not used. It was omitted from the London Pharmacopoeia of 1746 and 1788, and only restored in 1809; its reintroduction being chiefly due to experiments and recommendations by Baron Storch, who gave it in the form of an extract, in cases of epilepsy and other nervous and convulsive diseases.

 

Cultivation and Collection

 

Drug is usually obtained from cultivated biennial herb. Henbane will grow on most soils, in sandy spots near the sea, on chalky slopes, and in cultivation flourishing in a good loam, It requires a light, moderately rich and well-drained soil for successful growth and an open, sunny situation, but does not want much attention beyond keeping the ground free from weeds. The seed should be sown in the open, early in May or as soon as the ground is warm, as thinly as possible, in rows 2–2.5 feet apart, the seedlings thinned out to 2 feet apart in the rows, as they do not stand transplanting well. In order to more readily ensure germination, it is advisable to soak the seeds in water for 24 h before planting the unfertile seeds will then float on the top of the water and may thus be distinguished. Ripe seed should be grey, and yellowish or brown seeds should be rejected, as they are immature. Let the seeds dry and then sift out the smallest, using only the larger seeds. Only the larger seedlings should be reserved, especially those of a bluish tint. The soil where the crop is to be, must have been well manured, and must be kept moist until the seeds have germinated, and also during May and June of the first year. It is also recommended to sow seeds of biennial Henbane at their natural ripening time, August, in porous soil.

 

The ground must never be water-logged, drought and late frosts stunt the growth and cause it to blossom too early, and if the climatic conditions are unsuitable, espe-cially in a dry spring and summer, the biennial Henbane will flower in its’ first year, while the growth is quite low, but well manured soil may prevent this. Much of the efficacy of Henbane depends upon the time at which it is gathered. The leaves should be collected when the plant is in full flower. In the biennial plant, those of the second year are preferred to those of the first; the latter are less clammy and foetid, yield less extractive, and are medici-nally considered less efficient. The leaves of the biennial variety are collected in June or the first week of July and those of the annual in August. They are dried at 40–50°C in drying sheds, heated from outside. The dried drug is stored in airtight containers at low temperature, protected from light and moisture.

 

Characteristics

 

Both varieties are used in medicine, but the biennial form is the one considered official. The leaves of this biennial plant spread out flat on all sides from the crown of the root like a rosette; they are oblong and egg-shaped, with acute points, stalked and more or less sharply toothed, often more than a foot in length, of a greyish-green colour and covered with sticky hairs. These leaves perish at the appearance of winter. The flowering stem pushes up from the root-crown in the following spring, ultimately reaching from 3 to 4 feet in height, and as it grows, becoming branched and furnished with alternate, oblong, unequally lobed, stalk-less leaves, which are stem-clasping and vary considerably in size, but seldom exceed 9–10 inches in length. These leaves are pale green in colour, with a broad conspicuous midrib, and are furnished on both sides (but particularly on the veins of the under surface) with soft, glandular hairs, which secrete a resinous substance that causes the fresh leaves to feel unpleasantly clammy and sticky. Similar hairs occur on the sub-cylindrical branches.

 

The flowers are shortly stalked, the lower ones growing in the fork of the branches, the upper ones stalkless, crowded together in one side, leafy spikes, which are rolled back at the top before flowering, the hairy, leafy, coarsely toothed bracts becoming smaller upwards. The flowers have a hairy, pitcher shaped calyx, which remains round the fruit and is strongly veined, with five stiff, broad, almost prickly lobes. The corollas are obliquely funnel-shaped, upwards of an inch across, of a dingy yellow or buff, marked with a close network of lurid purple veins. A variety sometimes occurs in which the corolla is not marked with these purple veins. The seed-capsule opens transversely by a convex lid and contains numerous small seeds.


                                Hyoscyamus niger



Microscopy

 

The epidermis is covered with smooth layer of cuticle. Epidermis has slightly sinuous anticlinal walls and has covering and glandular trichomes along with anisocytic type of stomata. The covering trichomes are uni-seriate, multicellular with two to four-celled, and the glandular trichomes have uni-seriate stalk with two to six cells and ovoid multicellular glandular head. The mesophyll is usually dorsiventral with single layer of palisade parenchymatous cells only below the upper epidermis and rarely isobilateral. A crystal layer is present below the palisade, with tetragonal prisms or clusters of few components. In the midrib region it has long narrow arc of radially arranged xylem above the phloem and an endodermis consisting of starch. The remaining portion is covered with parenchyma with small supernumerary phloem.

 

The transverse section of stem shows a large central hollow and consists of numerous perimedullary phloem bundles in the pith region. Tetragonal calcium oxalate as prisms or clusters or in micro-sphenoidal sandy shape is also present in the pith.

 

Chemical Constituents

 

The chief constituent of Henbane leaves is the alkaloid Hyoscyamine, together with smaller quantities of Atropine and Hyoscine, also known as Scopolamine, The proportion of alkaloid in the dried drug varies from 0.045% to 0.14%. Other constituents of Henbane are a glucosidal bitter principle called hyoscytricin, choline, mucilage, albumin, calcium oxalate and potassium nitrate. On incineration, the leaves yield about 12% of ash. The chief constituent of the seeds is about 0.5–0.6% of alkaloid, consisting of Hyoscyamine, with a small proportion of Hyoscine, The seeds also contain about 20% of fixed oil.

 

 

Uses

 

It is used as antispasmodic, hypnotic and mild diuretic. The leaves have long been employed as a narcotic medicine. It is similar in action to belladonna and stramonium, though milder in its effects. The drug combines the therapeutic actions of its two alkaloids, hyoscyamine and hyoscine. Because of the presence of the former, it tends to check secretion and to relax spasms of the involuntary muscles, while through the narcotic effects of its hyoscine it lessens pain and exercises a slight somnifacient action. It will also relieve pain in cystitis. It is used to relieve the griping caused by drastic purgatives, and is a common ingredient of aperient pills, especially those containing aloes and colocynth.

 

Marketed Products

 

It is one of the ingredients of the preparations known as Muscle and joint rub (Himalaya Drug Company), Brahmi vati, Sarpagandhaghan Vati (Dabur) and Zymnet drops (Aimil Pharmaceuticals).

 

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