Gentian

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Chapter: Pharmacognosy and Phytochemistry : Drugs Containing Glycosides

Gentian consists of dried unfermented rhizomes and roots of Gentiana lutea Linn., belonging to family Gentianaceae.


GENTIAN

 

 

Synonyms

 

Gentian Root, Yellow Gentian Root.

 

Biological Source

 

Gentian consists of dried unfermented rhizomes and roots of Gentiana lutea Linn., belonging to family Gentianaceae.

 

Geographical Source

 

Mountanious regions of Central and south Europe, of France and Switzerland, of Spain and Portugal, the Pyr-enees, Sardinia and Corsica, the Apennines, the Mountains of Auvergne, the Jura, the lower slopes of the Vosges, the Black Forest and throughout the chain of the Alps as far as Bosnia and the Balkan States.

 

Cultivation and Collection

 

It is a perennial plant growing to 1.2 m by 0.6 m. For cul-tivation, a strong loamy soil is most suitable, the deeper the better, as the stout roots descend a long way down into the soil. Plenty of moisture is also desirable and a position where there is shelter from cold winds and exposure to sunshine. Old plants have large crowns, which may be divided for the purpose of propagation, but growing it on a large scale, seeds would be the best method. It is advantageous to keep the seed at about 10°C for a few days after sowing, to enable the seed to imbibe moisture. Following this with a period of at least 5–6 weeks with temperatures falling between 0 and –5°C will usually produce reasonable germination. They could be sown in a frame, or in a nursery bed in a sheltered part of the garden and the young seedlings transplanted. They take about three years to grow to flowering size. It is, however, likely that the roots are richest in medicinal properties before the plants have flowered.

 

Collection is done from two to five years old plants in spring. The rhizome and roots collected and dried. When fresh, they are yellowish-white externally, but gradually become darker by slow drying. Slow drying is employed to prevent deterioration in colour and to improve the aroma. Occasionally the roots are longitudinally sliced and quickly dried, the drug being then pale in colour and unusually bitter in taste.

 

Characteristics

 

When fresh, they are yellowish-white externally, but gradu-ally become darker by slow drying. Slow drying is employed to prevent deterioration in colour and to improve the aroma. Occasionally the roots are longitudinally sliced and quickly dried; the drug being then pale in colour and unusually bitter in taste, but this variety is not official.

 

The dried root as it occurs in commerce is brown and cylindrical, 1 foot or more in length, or broken up into shorter pieces, usually 1/2 inch to 1 inch in diameter, rather soft and spongy, with a thick reddish bark, tough and flexible, and of an orange-brown colour internally. The upper portion is marked with numerous rings, the lower longitudinally wrinkled. The root has a strong, disagreeable odour, and the taste is slightly sweet at first, but afterwards very bitter.

 


                   Gentiana lutea


Microscopy

 

The transverse section of root shows triarch primary xylem at the centre, where each primary bundle is represented by one to three very small vessels. The secondary xylem is very wide with parenchymatous and medullary rays not clearly marked. The drug also shows reticulately thickened xylem vessels very few being annular or spiral, scattered through-out the parenchyma of the xylem. Secondary phloem is wide and composed chiefly of parenchyma, with groups of sieve-tissue. The phloems are surrounded by a narrow parenchymatous phelloderm and externally are several rows of polygonal tabular, thin walled cork cells. Parenchyma cells in all regions of the root contain scattered needles of calcium oxalate crystals, about 3–6 μ long and 0.5–1.1 μ wide, also small prismatic crystals.

 

Chemical Constituents

 

Gentian contains bitter glycosides. The dried gentian root contains Gentinin and Gentiamarin, bitter glucosides, together with Gentianic acid (gentisin), the latter being physiologically inactive. Gentiopicrin, another bitter glucoside, a pale yellow crystalline substance, occurs in the fresh root, and may be isolated from it by treatment with boiling alcohol. Gentinin, crystalline glycoside is not a pure chemical substance, but a mixture of gentiopicrin and a colouring substance gentisin (gentianine) or gentlanic acid. Gentian contains a bitter trisaccharide, gentianose which on hydrolysis yields two molecules of glucose and one molecule of fructose. The saccharine constituents of gentian are dextrose, laevulose, sucrose and gentianose, a crystallizable, fermentable sugar. It is free from starch and yields from 3 to 4% ash.

 


 

Uses

 

Gentian root has a long history of use as an herbal bitter in the treatment of digestive disorders. It contains some of the most bitter compounds known and is used as a scientific basis for measuring bitterness. It is useful in states of exhaustion from chronic disease and in all cases of debility, weakness of the digestive system and lack of appetite. It is one of the best strengthened of the human system, stimulating the liver, gall bladder and digestive system, and is an excellent tonic to combine with a purgative in order to prevent its debilitating effects.

 

It is also used as anthelmintic, antiinflammatory, antiseptic, bitter tonic, cholagogue, emmenagogue, and febrifuge, refrigerant and stomachic. It is taken internally in the treatment of liver complaints, indigestion, gastric infections and anorexia. It should not be prescribed for patients with gastric or duodenal ulcers.

 

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