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Home , Fructoside, Glucoside, Liquiritin, Quercitron, Sarsasapogenin, Sinigrin

Glycosides may be defined as the organic compounds from plants or animal sources, which on enzymatic or acid give one or more sugar moieties along with non- sugar moiety. Glycosides play numerous important roles in living organisms. Many plants store important chemicals in the form of inactive glycosides; if these chemicals are needed, the glycosides are brought in contact with water and an , and the sugar part is broken off, making the chemical available for use. Many such plant glycosides are used as medications. In animals (including humans), poisons are often bound to sugar in order to remove them from the body.

Formally, a is any in which a sugar group is bonded through its carbon atom to another group via an O- or an S-glycosidic bond; glycosides involving the latter are also called thioglycosides. The sugar group is then known as the glycone and the non-sugar group as the aglycone or genin part of the glycoside. The glycone can consist of a single sugar group (monosaccharide) or several sugar groups (oligosaccharide).

Classification

Classification based on linkages

Based on the linkage of sugar moiety to aglycone part

1. O-Glycoside:-Here the sugar is combined with alcoholic or phenolic hydroxyl function of aglycone.eg:-digitalis. 2. N-glycosides:-Here nitrogen of amino group is condensed with a sugar ,eg- Nucleoside 3. S-glycoside:-Here sugar is combined with sulphur of aglycone,eg- glycosides. 4. C-glycosides:-By condensation of a sugar with a cabon atom, eg-Cascaroside, aloin.

Glycosides can be classified by the glycone, by the type of glycosidic bond, and by the aglycone.

By glycone

If the glycone group of a glycoside is , then the molecule is a ; if it is , then the molecule is a ; if it is glucuronic acid, then the molecule is a glucuronide; etc. In the body, toxic substances are often bonded to glucuronic acid to increase their water solubility; the resulting glucuronides are then excreted.

By type of glycosidic bond Depending on whether the glycosidic bond lies "above" or "below" the plane of the cyclic sugar molecule, glycosides are classified as α-glycosides or β-glycosides. Some such as α-amylase can only hydrolize α-linkages; others, such as emulsin, can only affect β-linkages.

By aglycone

Glycosides are also classified according to the chemical nature of the aglycone. For purposes of biochemistry and pharmacology, this is the most useful classification.

Alcoholic glycosides

An example of an alcoholic glycoside is which is found in the genus salix. Salicin is converted in the body into salicylic acid, which is closely related to aspirin and has analgesic, antipyretic and antiinflammatory effects.

Anthraquinone glycosides

These glycosides contain an aglycone group that is a derivative of anthraquinone. They are present in senna, rhubarb and aloes; they have a laxative effect.

Coumarin glycosides

Here the aglycone is coumarin. An example is apterin which is reported to dilate the coronary arteries as well as block calcium channels.those obtained from dried leaves of Psoralia corylifolia have main glycosides psoralin and corylifolin.

Cyanogenic glycosides

In this case, the aglycone contains a group, and the glycoside can release the poisonous if acted upon by some enzyme. An example of these is from . Cyanogenic glycosides can be found in the fruits (and wilting leaves) of the rose family (including cherries, apples, plums, almonds, , apricots, raspberries, and crabapples). Cassava, an important food plant in Africa and South America, contains cyanogenic glycosides and therefore has to be washed and ground under running water prior to consumption. Sorghum (Sorghum bicolor) expresses cyanogenic glycosides in its roots and thus is resistant to pests such as rootworms (Diabrotica spp.) that plague its cousin maize (Zea mays L.).

Flavonoid glycosides

Here the aglycone is a . This is a large group of flavonoid glycosides. Examples include:

• (aglycone: , glycone: Rutinose) • (aglycone: , glycone: Rutinose) • Rutin (aglycone: , glycone: Rutinose) • (aglycone: Quercetin, glycone: )

Among the important effects of are their antioxidant effect. They are also known to decrease capillary fragility.

Phenolic glycosides (simple)

Here the aglycone is a simple phenolic structure. An example is arbutin found in the Common Bearberry Arctostaphylos uva-ursi. It has a urinary antiseptic effect. Rutin found in rooibos tea.

Saponin glycosides

These compounds give a permanent froth when shaken with water. They also cause hemolysis of red blood cells. glycosides are found in liquorice. Their medicinal value is due to their expectorant effect.

Steroidal glycosides or cardiac glycosides

Here the aglycone part is a steroidal nucleus. These glycosides are found in the plant genera Digitalis, Scilla, and Strophanthus. They are used in the treatment of heart diseases e.g. congestive heart failure and arrhythmia.

Steviol glycosides

These sweet glycosides found in the plant bertoni have 40-300 times the of . The two primary glycosides, stevioside and , are used as natural sweeteners in many countries. These glycosides have steviol as the aglycone part. Glucose or rhamnose-glucose combinations are bound to the ends of the aglycone to form the different compounds.

Isothiocyanate glycosides

As the name implies, these compounds contain sulfur. Examples include , found in black , and , found in white mustard.

1 . Steroidal glycosides or cardiac glycosides

Many of the plants known to contain cardiac or cardiotonic glycosides have long been used as arrow poisons (e.g. Strophanthus) or as heart drugs (e.g. Digitalis). They are used to strengthen a weakened heart and allow it to function more efficiently, though the dosage must be controlled very carefully since the therapeutic dose is so close to the toxic dose. In plants, cardiac glycosides are confined to the Angiosperms, but are found in both and dicotyledons. The therapeutic action of cardioactive glycosides depends on the structure of the aglycone, and on the type and number of sugar units attached. Two types of aglycone are recognized, , e.g. digitoxigenin from Digitalis purpurea and , e.g. hellebrigenin from Helleborus niger

The cardenolides are more common, and the plant families the Apocynaceae (e.g. Strophanthus), Liliaceae (e.g. Convallaria), and Scrophulariaceae (e.g. Digitalis) yield medicinal agents. The rarer bufadienolides are found in some members of the Liliaceae (e.g. Urginea) and Ranunculaceae (e.g. Helleborus).

Biosynthesis: Formed through mevalonate and deoxyxylulose pathway

Test for cardiac glycosides (Keller-Killani test): Five ml of extract was treated with 2 ml of glacial acetic acid containing one drop of ferric chloride solution. This was underlayed with 1 ml of concentrated sulphuric acid. A brown ring of the interface indicates a deoxysugar characteristic of cardenolides. A violet ring may appear below the brown ring, while in the acetic acid layer, a greenish ring may form just gradually throughout thin layer

Digitalis purpurea

Source:- Digitalis leaf consists of the dried leaf of the red foxglove Digitalis purpurea (Scrophulariaceae).

Geographical source and collection :- The plant is a biennial herb, common in Europe and North America, which forms a low rosette of leaves in the first year, and its characteristic spike of purple (occasionally white) bellshaped flowers in the second year. It is potentially very toxic, but is unlikely to be ingested by humans. Digitalis purpurea is cultivated for drug production, principally in Europe, the first year leaves being harvested then rapidly dried at 60°C as soon as possible after collection. This procedure is necessary to inactivate hydrolytic enzymes which would hydrolyse glycoside linkages in the cardioactive glycosides giving rise to less active derivatives.

Chemical constituents:- The cardioactive glycoside content of Digitalis purpurea leaf is 0.15–0.4%, consisting of about 30 different structures. The major components are based on the aglycones digitoxigenin, gitoxigenin, and gitaloxigenin, the latter being a formate . The glycosides comprise two series of compounds, those with a tetrasaccharide glucose– (digitoxose)s – unit and those with a trisaccharide (digitoxose)3 – unit. The latter group (the secondary glycosides) are produced by partial hydrolysis from the former group (the primary glycosides) during drying by the enzymic action of a β-glucosidase, which removes the terminal glucose. Thus the principal glycosides in the fresh leaves, namely purpureaglycoside A and purpureaglycoside B, are partially converted into and gitoxin respectively ,which normally predominate in the dried leaf.

Use:- Glycosides of the gitoxigenin series are less active than the corresponding members of the digitoxigenin-derived series. Digitoxin is the only compound routinely used as a drug, and it is employed in congestive heart failure and treatment of cardiac arrhythmias, particularly atrial fibrillation.

Digitalis lanata

Source:- Digitalis lanata (Scrophulariaceae), the Grecian foxglove, is a perennial or biennial herb from Southern and Central Europe, and differs in appearance from the red foxglove by its long narrow smoother leaves, and its smaller flowers of a yellow-brown colour. Geographical source and collection:-

It is cultivated in Europe, the United States and South America, and is harvested and dried in a similar manner to D. purpurea.

Chemical constituents:-

Contains individual cardiac glycosides, principally and lanatoside C The total content of up to 1% is two to three times that found in D. purpurea. The D. lanata cardiac glycosides are based on five aglycones, digitoxigenin, gitoxigenin, and gitaloxigenin, as found in D. purpurea, plus digoxigenin and diginatigenin ,which do not occur in D. purpurea. Lanatosides B, D, and E are minor components derived from gitoxigenin, diginatigenin, and gitaloxigenin respectively. Compounds like acetyldigitoxin and acetyldigoxin as well as digitoxin and digoxin are present in the dried leaf as decomposition products from lanatosides A and C respectively.

Use:-

Digitoxin is used in congestive heart failure and atrial fibrillation. Lanatoside C and deslanoside (desacetyl-lanatoside C) have also been employed, though not to the same extent. They have very rapid action and are suited for treatment of cardiac emergencies by injection. Strophanthus

Source:- Strophanthus is the dried ripe seeds of Strophanthus kombe or S. gratus (Apocynaceae), Geographical source:-

These are tall vines from equatorial Africa. Strophanthus kombe´ has a history of use by African tribes as an arrow poison.

Chemical constituents:- The seeds contain 5–10% cardenolides, a mixture known as K-strophanthin. This has little drug use today, though it was formerly used medicinally as a cardiac stimulant. The main glycoside (about 80%) is K-strophanthoside with smaller amounts of K- strophanthin-β and cymarin. These are derivatives of the aglycone strophanthidin. Strophanthus gratus contains 4–8% of (G-strophanthin.

Use:-

Ouabain (G-strophanthin) is a potent and acts quickly. It has been used for emergency treatment in cases of acute heart failure. It is still official in many pharmacopoeias.

Squill

Source:- Squill (white squill) consists of the dried sliced bulbs of the white variety of Urginea maritime (formerly Scilla maritima; also known as Drimia maritima) (family:Liliaceae)

Geographical source:- grows on seashores around the Mediterranean.

Chemical constituents:-

The plant contains bufadienolides (up to 4%), principally scillaren A and proscillaridin A The aglycone of scillaren A is scillarenin. White squill is employed for its expectorant action in preparations such as linctus. Large doses cause vomiting and a digitalis-like action on the heart.

Red squill is a variety of Urginea maritima that contains an anthocyanin pigment and bufadienolides that are different from those of the white squill. The main glycosides are glucoscilliroside and scilliroside , of scillirosidin. Red squill is mainly been employed as a rodenticide.

2. Saponin glycosides

Steroidal widely distributed in nature. They posseses some common characterestics:- A) They produce foam in aqueous solution B) They cause hemolysis of RBC. Aglycone of the saponin glycosides are known as . They are found in many families, especially the Dioscoreaceae (e.g. Dioscorea) and the Liliaceae (e.g. , Trillium). e.g. dioscin (Dioscorea). Acid hydrolysis of dioscin liberates the aglycone .

Biosynthesis: Formed through mevalonate and deoxyxylulose pathway

Test for saponin: About 2 g of the powdered sample was boiled in 20 ml of distilled water in a water bath and filtered. 10ml of the filtrate was mixed with 5 ml of distilled water and shaken vigorously for a stable persistent froth. The frothing was mixed with 3 drops of and shaken vigorously, then observed for the formation of emulsion.

Dioscorea

Source:- Comprises of dried tubers of Dioscorea delitoidea ,Dioscorea takora of family Dioscoreacea

Geographical source:- Important sources of Dioscorea are Mexico, South Africa and China

Chemical constituents:- The saponin content of the tubers varies, usually increasing as tubers become older. The principal in the species given above is diosgenin, with small quantities of the .

Use:- Powdered Dioscorea (wild yam) root or extract is used to treat the symptoms of menopause as an alternative to hormone replacement therapy, rheumatic arthritis, Source of hormones.

Sarsaparilla Source: Sarsaparilla consists of the dried roots of various Smilax species (Liliaceae), including S. regelii, and S. febrifuga. Constituents:- It has some potential as a raw material for the semi-synthesis of medicinal , being a source of sarsasapogenin and smilagenin. The roots contain 1.8–2.4% steroidal saponins, including parillin.

Use:- In the treatment of syphilis, rheumatism, and skin diseases, employed as flavouring in the manufacture of non-alcoholic drinks.

Glycyrrhiza glabra Source:- Glycyrrhizae consists of the dried roots and rhizomes of Glycyrrhiza glabra L. and its varieties or of Glycyrrhiza uralensis Fisch.

Geographical distribution

Native to central and southwestern Asia and the Mediterranean region. It is cultivated in the Mediterranean basin of Africa, in southern Europe, and in India.

Major chemical constituents:- The major constituents are triterpene saponins. (glycyrrhizic acid, glycyrrhizinic acid) is the major component (2–9%); minor components occur in proportions that vary depending on the species and geographical location. Glycyrrhizin occurs as a mixture of and calcium salts . It is a monodesmoside, which on hydrolysis releases two molecules of D-glucuronic acid and the aglycone glycyrrhetic (glycyrrhetinic) acid (). Glycyrrhizin is 50 times sweeter than that of sucrose. Flavonoid constituents include and isoliquiritigenin.

Medicinal uses

As a demulcent in the treatment of sore throats, and as an expectorant in the treatment of coughs .Also in the prophylaxis and treatment of gastric and duodenal ulcers, and dyspepsia.As an anti-inflammatory agent in the treatment of allergic reactions, rheumatism and arthritis, to prevent liver toxicity, and to treat tuberculosis and adrenocorticoid insufficiency.

. 3. glycosides or Anthraquinone glycosides

They are found abundantly in dicot plant families: Ericaceae, Euphorbiaceae, Leguminoseae, and Rubiaceae. These glycosides contain an aglycone group that is a derivative of anthraquinone.

Aloe

Source: Aloe is the dried juice of the leaves of Aloe vera (L.) or of A. ferox Mill. and its hybrids with A. africana Mill. and A. spicata Baker (Liliaceae).

Geographical distribution: Native to southern and eastern Africa, and subsequently introduced into northern Africa, the Arabian peninsula, China, Gibraltar, the Mediterranean countries, and the West Indies. It is commercially cultivated in Aruba, Bonaire, Haiti, India, South Africa, the United States of America, and Venezuela

Major chemical constituents: Aloe contains as its major and active principles hydroxyanthrone derivatives, mainly of the aloe-emodin-anthrone. The major constituent is known as barbaloin (aloin). It also contains hydroxyaloin (about 3%). Barbaloin (_aloin) is a mixture of aloin A and B . A. ferox also contains aloinoside A & B .

Medicinal uses:

Short-term treatment of occasional constipation. Treatment of seborrhoeic dermatitis, peptic ulcers, tuberculosis, and fungal infections, and for reduction of blood sugar (glucose) levels.

GENERAL TESTS :— 1) Borax test:- Mix 1 Gm. of Aloes with 10 mils of hot water and dilute 1 mil of this mixture with 100 mils of water; a green fluorescence is produced upon the addition of an aqueous solution of borax . 2) Dilute 1 ml of the original aqueous mixture of Aloes with 100 mils of water, and shake it with 10 ml of ; upon separating the benzene solution and adding to it 5 ml of ammonia water a permanent deep rose color is produced in the lower layer.

RHUBARB

Source:- The dried rhizome and roots of Rheum officinale, Rheum palmatum of family polygonaceae

Geographical source:- Northern China, Siberia, and European Russia

CONSTITUENTS: A mixture of different coloring principles of a somewhat resinous quality, each having a peculiar solubility of its own: Chrysophan, emodin, aporetin, erythroretin, rheumic acid, and rheotannic acid; also starch, calcium oxalate, pectin, and arabic acid.

ACTION AND USES : Purgative and astringent. It has been highly esteemed as an antidysenteric remedy because of the fact that the cathartic principles are accompanied by the antiseptic action of chrysophan, and because catharsis is followed by an astringent and tonic effect upon the mucous lining.

EMODIN TEST:- Boil 0.100 Gm. of powdered rhubarb with 10 ml of an aqueous solution of potassium hydroxide 1 in 100), allow it to cool, filter, acidulate the filtrate with and shake it with 10 mils of ether; on standing, the ethereal layer should be colored yellow. On shaking this ethereal solution with 5 mils of ammonia water, the latter should be colored cherry-red (presence of emodin) and the ethereal layer should remain yellow (presence of chrysophanic acid)

4. FLAVANOID GLYCOSIDES Flavanoid glycosides are mostly occur as o-glycosides or c-glycosides containing in the cell sap of higher plants belonging to the families:-Compositae, Leguminosae, Rutaceae, Umbelliferae

Different types of flavanoids glycosides are:- 1. Flavone glycosides Eg:-Apiin and diosmin 2. Flavonol glycosides Eg:-Rutin and Quercetin 3. glycosides Eg:- Hesperidin and 4. Chalcone glycosides Eg:- 5. Isoflavanoid glycosides Eg:-Tephrosin and prunetrin 6. Anthrocyanidin glycosides Eg:-Cyanidin and malvidin

Flavonoids are particularly beneficial, acting as antioxidants and giving protection against cardiovascular disease, certain forms of cancer, and, it is claimed, age-related degeneration of cell components. Their polyphenolic nature enables them to scavenge injurious free radicals such as superoxide and hydroxyl radicals. Quercetin in is almost present in substantial amounts in plant tissues, and is a powerful antioxidant, chelating metals, scavenging free radicals, and preventing oxidation of low density lipoprotein.

Flavonoids in red wine (quercetin, kaempferol, and anthocyanidins) and in tea (catechins and catechin gallate ) are also demonstrated to be effective antioxidants. Flavonoids contribute to plant colours, yellows from chalcones and flavonols, and reds, blues, and violets from anthocyanidins. Even the colourless materials, e.g. , absorb strongly in the UV and are detectable by insects, probably aiding flower pollination.

Chalcones act as precursors for a vast range of flavonoid derivatives found throughout the plant kingdom. can then give rise to many variants on this basic skeleton, e.g. flavones, flavonols, anthocyanidins, and catechins

Chemical tests:-

1.It exhibits a brown fluorescence under UV light 2.It gives yellow precipitate with basic lead acetate solution. 3.It gives greenish brown precipitate with ferric chloride. 4.IT produces a silver mirror with ammoniacal silver nitrate solution.

Biosynthesis:-Through acetate pathway and shikimic acid pathway.

WHITE OAK

Source:- The bark of Quercus alba is collected from trunk or branches ten to twentyfive years of age and deprived of the periderm.

CONSTITUENTS.—Quercitannic acid 6 to 11 per cent., a coloring matter, a bitter principle (quercin), sugar (quercite), resin, etc. The active principles are soluble in water and alcohol. The amount of tannin varies with the species, the part of the tree, and the season of the year when gathered; the young bark contains a greater proportion than the old. is a coloring principle . This glucoside splits up by hydrolysis into quercetin and isodulcite, or rhamnose. Quercetron (Xantho rhamnin) forms yellowish crystals, odorless and tasteless, but in hot aqueous or alcoholic solution has a bitter .

ACTION AND USES—Astringent and tonic, generally used externally in infusion or decoction as an astringent and tonic, injection, etc

BITTER ORANGE PEEL and SWEET ORANGE PEEL

Source:- The dried rind of the unripe fruit of Citrus vulgaris Risso(bitter) And the undried outer rind of the ripe fruit of Citrus Aurantium Linn(sweet).

Geographical source:-The orange tree is cultivated in the south of Europe, in the Azores, and in the United States-Southern States and California

CONSTITUENTS :-Volatile oil (contained in vesicles of the epidermis), hesperidin, ash, and a white principle which turns black with ferric salts.

ACTION AND USES:-Tonic, carminative, and stomachic.

BUCHU

Source:-The dried leaves of Barosma Betulina commercially as short buchu, or of Barosma Serratifolia ,known commercially as long buchu, with which may be mixed not more than 10 per cent of the stems of the plants or other foreign matter.

CONSTITUENTS.—Volatile oil , barosma ,the bitter principle is rutin , resin is also present.

ACTION AND USES:-A mild diuretic in disorders of the urinogenital Organs, a stimulant and stomachic. 5. CYANOGENETIC GLYCOSIDES

Cyanogenic glycosides are a group of mainly plant-derived materials, which liberate hydrocyanic acid (HCN) on hydrolysis, and are thus of concern as natural toxicants. The group is identified by amygdalin , a constituent in the kernels of bitter almonds ( amygdalus ; Rosaceae) and other Prunus species such as apricots, peaches, cherries, and plums.

When plant tissue containing a cyanogenic glycoside is crushed, glycosidase enzymes ,usually located in different cells are brought into contact with the glycoside and begin to hydrolyse it. Thus, amygdalin is hydrolysed sequentially by β-glucosidase-type enzymes to and then mandelonitrile. Cyanogenetic glycoside contain nitrogen ,but the sugar moiety is attached to oxygen. The enzyme emulsin found in ,consists of two enzymes amygdalase and prunase.

The main amino acids utilized in the biosynthesis of cyanogenic glycosides are phenylalanine (e.g. prunasin, sambunigrin, and amygdalin), tyrosine (e.g. dhurrin from sorghum (Sorghum bicolor; Graminae/Poaceae)), valine (e.g. from (Linum usitatissimum; Linaceae)), isoleucine (e.g. from flax), and leucine (e.g. heterodendrin from Acacia species (Leguminosae/Fabaceae)

Chemical test:-Sodium picrate test

A strip of filter paper is dipped in 10% aqueous solution of picric acid. It is drained and redipped in 10% sodium carbonate solution and drained again. To powdered drug in a flask ,water is added to moisten it. Sodium picrate is kept on the mouth of the flask. Hydrocyanic acid vapours turn the paper brick red or maroon coloured.

Biosynthesis:-Through shikimic acid and phenylalanine pathway.

WILD CHERRY BARK

Source:- The bark of Prunus serotina of family Rosaceae, collected in autumn and carefully dried and preserved.

Geographical source:- United States and Canada.

CONSTITUENTS:- Tannin, bitter cyanogenetic glycoside prunasin, resin, starch, volatile oil and hydrocyanic acid

ACTION AND USES:-Tonic and sedative. Owing to the bitter principle it is a stomachic and bitter tonic. The syrup forms the basis of many of the cough syrups. BITTER ALMOND

Source:- The ripe seed of Prunus Amygdalus of family Rosaceae.

Geographical :-Western Asia and Southern Europe, Spain and Southern France

Constituents:-Amygdalin,emulcin, enzymes such as amygdalase,prunase.

Use:- As a sedative due to the presence of HCN. - Fixed oils in bitter almond has demulscent action.

LINSEED

Source:- The ripe seed of Linum usitatissimum of family liliaceae.

CONSTITUENTS.—Glycoside Linamarin, A viscid yellow fixed Oil, proteids , resin, wax, a small quantity of amygdalin.

ACTION AND USES.—The whole seed is used in decoction as a demulcent; ground flaxseed is a favorite for poultices; the expressed oil is laxative, and, in combination with lime-water is employed as a protective in burns, etc.

6. ISOTHIOCYANATE GLYCOSIDES

Isothiocyanate glycosides contain sulphur and present in many Cruciferous plants. On hydrolysis they produce isothiocyanate aglycones. Sinigrin from black mustard and sinalbin from white mustard are isothiocyanate glycosides. Sinigrin on hydrolysis in the presence of enzyme myrosin, yields ,glucose and potassium acid sulphate. These glycosides are irritant and employed as counter irritant in neuralgia and rheumatism.

Chemical test:- 1. The powdered black mustard seeds on treatment with sodium hydroxide yields bright yellow colouration. 2. The hydrolysed products of sinalbin(white mustard) are crystalline and give rise a bright yellow colouration in alkaline medium.

BLACK MUSTARD

Source: The ripe seed of Brassica nigra of the family Cruciferae.

HABITAT.—Asia and Southern Europe; cultivated.

Constituents:- Thioglycoside named Sinigrin, volatile oils, protein, fixed oils. ACTION AND USES :- Externally a powerful rubefacient and counter-irritant, internally emetic, especially valuable in cases of poisoning by narcotics from its reflex stimulation of the heart and respiration.

WHITE MUSTARD

Source:- The seed of Brassica alba of the family Cruciferae.

HABITAT:- Asia and Southern Europe

Constituents:- Thioglycoside sinalbin, volatile oil, proteins.

Use:- Rubefacient and counter-irritant, internally emetic.

7. PHENOLIC GLYCOSIDES

Simple phenolic glycosides have their aglycone portion loaded with either phenolic moieties , alcoholic moieties or carboxylic acid functions. Commonly found phenolic glycosides are Salicin, populin, arbutin , gaultherin etc.

Biosynthesis:- Through shikimic acid pahway. Chemical tests:-

1. It gives a bright yellow coloration with conc.sulphuric acid that fades out on addition of water. 2. It yields blue coloration with ferric chloride solution.

SALIX (WILLOW)

Source:- The bark of Salix alba and S. Purpurea of the family Rosaceae

Habitat: Europe; naturalized in North America.

CONSTITUENTS:-Tannin about 12 per cent., most abundant in the white willow, and a bitter neutral principle, salicin, which is the active glucosidal constituent.It may found combined with populin(benzoyl salicin) in some species. Salicin is hydrolysed in presence of emulsin to form saligenin and D-glucose.

Use:-Analgesic, stomachic, antirheumatic agent.

POPULUS

Source:- The bark of Populus tremuloides of the family Salicacea. Habitat: Northern North America and Siberia.

Constituents: Its active principle, populin, is analogous to the salicin of salix . Some species of Populus, are covered with a resinous exudation which is impregnated with a fragrant volatile oil, and is very similar in medicinal action to the turpentine oleoresins.

Use:- Tonic and febrifuge.

8. Coumarin glycosides

The hydroxylation of cinnamic acids ortho to the side-chain as seen in the biosynthesis of salicylic acid is a crucial step in the formation of a group of cinnamic acid lactone derivatives, the coumarins. Thus, cinnamic acid and 4-coumaric acid give rise to the coumarins (coumarin and umbelliferone). Other coumarins with additional oxygen substituents on the aromatic ring, e.g. aesculetin and , appear to be derived by modification of umbelliferone.

Coumarins are widely distributed in plants, and are commonly found in families such as the Umbelliferae/Apiaceae and Rutaceae, both in the free form and as glycosides. Coumarin itself is found in sweet clover (Melilotus species; Leguminosae/ Fabaceae) Dicoumarol is degradative a product of coumarins with blood anticoagulant properties.

Chemical test:- The drug is dissolved in minimum amount of alcohol and on addition of little sodium hydroxide shows a yellow fluorescence.

Psoralens

Psoralens are linear furocoumarins which are widely distributed in plants (Apium graveolens; Umbelliferae/Apiaceae)

The most common examples are psoralen, bergapten, xanthotoxin, and isopimpinellin. Plants containing psoralens have been used internally and externally to promote skin pigmentation and sun-tanning . The psoralen, because of its extended chromophore, absorbs in the near UV and allows this radiation to stimulate formation of melanin pigments

MELILOTUS

Source:- The flowering tops of Melilotus officinalis of the family Leguminoseae.

Constituents:- They contain melilotol (a fragrant volatile oil), coumarin (the aromatic principle), cumaric acid, and melilotic (hydrocumaric) acid, having a honey-like odor. Use:-An infusion is used as a stimulant and antispasmodic in whoopingcough, but it is generally used as a local anodyne in poultices.

DIPTERYX (TONKA BEAN)

Source: - The fruit of a large tree, Dipteryx odorata of the family Leguminosae

Constituents: - crystalline principle is coumarin, cumaric acid.

Use: - Used as a flavour, as an adulterant of , and to flavour cigars.