ANTHRAQUINONE GLYCOSIDES

Anthraquinone glycosides upon hydrolysis yield aglycone, which are di, tri or tetra hydroxy anthraquinone or derivative of these compounds. The free anthraquinone aglycone exhibits little therapeutic activity.

The sugar residue facilitates translocation and absorption of aglycone at the site of action. These compounds are stimulant, cathartic or purgation and they exert their action by increasing the tone of smooth muscle in the wall of large intestine.

Chemical Tests: -

There are two chemical tests for anthraquinone glycosides.

(i) When alkali is added to the powdered drug or to the section of drug red colour produced serve to locate the anthraquinone derivative in the tissue e.g. in the case of carcara bark, when treated with alkali the medullary rays assume red colour.

(ii) Borntrager Test: -

Powdered drug is mixed with ether, which is filtered, and to the filtrate add caustic soda and aqueous ammonia. Red, pink or violet colour produced indicates the presence of anthraquinone glycoside.

Aloe

B.O. Aloe ferox

Aloe barbadensis

Aloe perryi

P.U. Dried juice of leaves

Family Liliaceae.

Habitat: -

These are about 150 species of Aloe.

Most of them are indigenous to Africa and naturalized in Europe. Specie indigenous to Pakistan is Aloe spinosissima.

Habit: -

Plants are herb, shrub or trees. Out of above three Aloe ferox is 7 meter, in height. These plants are xerophytic (characteristic of desert plant). Leaves are pink, fleshy. Strongly cuticularized with prickly margin.

Collection and Drying: -

Leaves are cut from 9-10 months old plant in March and April. They are placed in V-shaped trough is placed on an inclined so that the juice from the leaves may be led into a vessel. This juice is then evaporated to a sufficient degree and then is placed in a metal container and allowed to harden. The odour of drug is characteristic and taste is bitter.

Constituents: -

Aloe contains a no. of anthraquinone glycosides. The principal of which Barbaloin. It is Aloe emodin anthrone c-10 glycoside. So it is an example c-glycoside.

Uses: -

Purgative

Cathartic

Fresh mucilaginous juice of the leaves is used for the treatment of skin burns, skin abrasion and other skin irritations.

Used in compound Benzoin tinctures.

Chemical Tests: -

(i) When 2 ml of Nitric acid is added to 5ml. 1% aq solution of Aloe it gives pale brown colour.

(ii) When few crystals of sod. nitrite along with a little acetic acid is added to 5ml 1% soln. of aloe. It gives brown colouration due to isobarbaloin.

Cascara

B.O. Rhamnus purshiana, Cascara sagrada

Family Rhamnaceae

P.U. Dried bark

Habitat: -

These plants are indigenous to the coast of North America. Commercial supply comes from Washington, California and Oregon. Systematic cultivation is carried in Canada and U.S.A.

Collection: -

Bark is collected from mid April to the end of August. Cut into small pieces and dried in shade to retain colour. Its fracture is short and glandular in outer layers and somewhat fibrous in phloem region. Odour of bark is slight and characteristic. Taste is bitter.

Constituents: -

Primary glycosides i.e. cascaroside A and B and cascaroside C and D. These primary glycosides are more effective.

Cascaroside A and B are related to Barbaloin while cascaroside C and D are related to chrysoloin.

Plants also contain two Aloins.

(i) Barbaloin.

(ii) Chrysoloin.

Chrysophanol, Aloe emodine and emodine in free state are least effective.

Uses Of Cascara: -

Purgative

Cathartic

Veterinary work.

The primary glycosides are more active then aloins while the free anthraquinone have little purgative property. The cascarosides have a sweet and more pleasant taste than the aloins and it is evaluated that aloins and cascarosides should be extracted separately.

Rhubarb

B.O. Rheum emodi

Rheum webbianum (Indian Rhubarb)

Rheum palmatum

Rheum officinale.

Family Ploygonaceae

P.U. Dried rhizome and roots.

Collection: -

Plants are perennial herbs. Underground portion consists of strong vertical rhizomes and roots are collected from 6-9 years old plants and dried artificially or in the sun. the drug has a frim texture, non-shrunken appearance, dried yellow surface, aromatic odour.

Taste is bitter and is astringent.

Constituents: -

Principal constituent is related to Rhein anthrone.

Drug also contain astringent principal i.e. rheotannic acid, gellic acid, glucogallin and other constituents like emodin, aloe-emodin, chrysophonol in free state and their glycosides but in trace amount.

Uses: -

Cathartic, purgative

In addition to this secondary astringent action in indigestion. Due to astringent action this drug is not commonly used.

Chemical Test: -

A little powder is shaken with 10ml of ferric chloride solution mixed with 5ml of hydrochloric acid and heated on a water bath for 10min. after filtration and cooling filtrate is extracted with 10ml of carbon tetrachloride. The organic layer is separated, washed with 5 ml of water and shaken with 5ml of solution of ammonia. Official rhubarb gives a rose pink to cherry red colour.

Senna

B.O. Cassia acutifolia,

Cassia angustifolia.

Family Leguminosae

P.U. Dried leaflets.

Habit: -

Senna plants are shrub, almost 2-meter in height. The leaves are compound and paripinnate.

Collection: -

Senna is collected mainly in September. The branches bearing leaves and pods are collected by cutting the tops of plants about 15cm above the ground.

The stems and fruits (pods) are separated from leaflets by means of seives. This step is separation. Then garbling takes place. Then tossed in shallow trays. The leaflets being lighter remains on the top of the tray while sand particles settle down. Blue green leaflets are best leaves. The branches bearing leaves and pods are dried in the sun.

Constituents: -

Principal constituents are sennoside A, B, C and D.

Uses: -

Senna is an effective purgative for either habitual constipation or occasional use. It lacks astringent after effect of rhubarb.

Saponins

Plant materials containing Saponins have long been used as detergents. For example in Europe root of Saponaria officinalis and in South America the bark of Quilage saponaria.

Diagnostic Characteristics Of Saponins: -

(i) They form colloidal solution with water, which foams upon shaking.

(ii) They have bitter taste and the drugs containing them are usually sternutatory or irritant to mucous membrane.

(iii) They destroy RBCs by haemolysis

(iv) They are toxic especially to cold-blooded animals.

(v) Saponins are extracted from plants by hot water or alcohol and after concentration of extract they are precipitated by ether.

On the basis of chemical nature of aglycone they are classified into two groups.

(i) Steroidol saponins (Tetracyclic triterpenoids)

(ii) Pentacyclic triterpenoids.

Steroidal saponins are of great interest and importance owing to their relation ship with compound like vit. D, cortisone, cardioactive glycosides and sex hormones. They are used as starting material for the synthesis of these compounds. Some species of digitalis and strophanthus contain both cardiac as well as saponin glycosides.

Pentacyclic triterpenoids saponins are abundant in many dicotyledonous families.

Basic Nucleus of Saponins

Glycyrrhiza

B.O. Glycyrrhiza glabra (variety lypica)

Family Leguminosae

P.U. Dried rhizome and roots.

Habit: -

Plants are perennial herbs about 1m in height with imperipinnate compound leaves.

There are three varieties;

(i) Typica

This is commercially known as saponish liquorice. It is cultivated in Spain, Italy, France, Germany, England, U.S.A.

(ii) Glandulifera

This is commercially known as Russian liquorice. It is cultivated in southern and central parts of Russia.

(iii) Violacea

(Due to colour of flower which is violet) It is commercially known as Persian liquorice. It is cultivated in Iran and Iraq.

Characteristics: -

Fracture is short in bark and splintry in wood. Odour is slight but characteristic. Taste is sweet.

Collection: -

Rhizomes and roots are collected from 3-4 years old plants and are air dried. Drying process takes 4-6 months.

In Spain and Turkey a considerable amount of crop is extracted with water. The liquid being purified and evaporated and resulting extract is molded into sticks or other forms.

Constituents: -

The chief constituent is glycyrrhizic acid or glycyrrhizin. It is 150 times as sweet as sugar. Upon hydrolysis yield a glycone, glycyrrhotinic acid or glycyrrhetic acid and two-glucoronic acid. Other constituents are flavonoid, glycoside liquiritin and isoliquiritin. Drug also contains glucose, mannitol and 20% starch.

Uses: -

Liquorice possesses demulcent, laxative and expectorant properties.

Many laxatives contain anthraquinone glycosides and liquorice because liquorice potentiates anthraquinone drugs by sensitizing the intestine.

Glycyrrhiza is also used as Flavouring agent and frequently applied to mask the bitter taste of a drug i.e. Aloe, quinine and Amm. Chloride. Commercially liquorice is added to chew gum, chocolate, candy cigarette.

Currently Glycyrrhiza and sarsaparilla roots both are used in the treatment of peptic ulcer.

Ginseng

(Chinese or oriental ginseng)

B.O. Panax ginseng

P.U. Dried root

Family Araliaceae.

Panax is Greek word (pan-axos means all healing)

Habitat: -

These plants are indigenous to East Asia and cultivated in Korea, China Japan and Russia.

Collection: -

Plants are harvested in summer or autumn, when they are 6-7 years old. The roots are dried in sun after removal of outer layers to produce white ginseng. The red ginseng is obtained by first staining the root in large pressure vessels when they are dried artificially in the over and finally they are sun dried.

Characteristics: -

Fracture is short odour is slightly aromatic. Taste is sweetish, aromatic and mucilaginous and some times slightly bitter.

Constituents: -

Active constituents are complex mixture of saponin which are termed ginsenosides and these are designated as R, Ra, Rb and Rb2 according to Rf values. This is termed by Japanese scientist. Russian scientist gives the name. Panaxosides A, B, C etc. upon hydrolysis Panaxosides yield panaxadiol, panaxatriol and oleanolic acid. First two compounds appear to be artefact (Not naturally occur but appear upon hydrolysis). In addition to these, ginseng also contain sterols, volatile oils, vitamins (B₁.B₂,B₁₂) amino acids, sugars (glucose, fructose, mannitol and sucrose).

Uses: -

Ginseng possesses diuretic, carminative, tonic and stimulant properties. It reportedly reduces blood sugar conc. and acts favourably on metabolism i.e. C.N.S and endocrine secretions. In Chinese and orient medicines, it is employed in treatment of anemia, insomnia, diabetes and gastritis.