Anthracene Glycosides - PowerPoint Presentation

Slide1

Anthracene Glycosides ( Anthraquinone Glycosides)

1

Anthracene

glycosides represent a major class of glycosides. They are abundantly found in

various

plant families, such as:

Ericaceae

,

Liliaceae

.

Euphorbiaceae

,

Leguminoseae

,

Lythreaceae

,

Polygonaceae

,

Rhamnaceae,and

Rubiaceae

. Besides, they are

also present

in certain varieties of fungi and

lichens.

______________________________________________________

1. Aloes

Synonym: Aloe

Biological Source: Aloe is the dried latex of leaves of various species of Aloes, namely:

Aloe

barbadensis

Aloe

ferox

Aloe

perryi

All these species belong to the family

Liliaceae

.

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Chemical Constituents: Aloe-emodin occurs in the free state and as a glycosides in various species of Aloe and also in Rheum (Rhubarb). Aloe barbadensis

contains about two and half times the amount of aloe emodin when compared to Aloe ferox

.The glycosides of anthranols, dianthrones, and oxanthrones i.e., the reduced derivatives of anthraquinones, invariably found in various plant substances.

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These plant products do make an appreciable contribution to the inherent therapeutic values of the naturally occurring substances.

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Both anthrones and anthranols mostly occur either as free or combined as glycosides. From a close look at their respective structures it may be observed that they are reduced anthraquinone derivatives.

Both anthrone and anthranol are isomeric in nature; however, the latter may be partially converted to the former, which is essentially a non-fluorecent

substance and is not soluble in

alkaline solutions. Generally, the anthrones are converted on oxidation into their corresponding anthraquinones, namely: oxanthrone and dianthrone. Aloe yields not less than 50% of water soluble extractives. It also contains volatile oil to some extent that imparts a characteristic odour to it.

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Uses1. used as a purgative.2. Aloes find its usefulness as an external aid to painful inflammatory conditions.

3. Aloe gel made from the mucilaginous latex of A. vera is frequently employed in the treatment and cure of radiation burns to get immediate relief from

itchings

and pains.4. Aloe usually causes gripping and is, therefore, administered along with carminatives.

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2. Rhubarb:(Rheum)Biological Source: Rhubarb is the rhizome and roots of Rheum officinale(Polygonaceae)Chemical Constituents

Rhubarb essentially contains mainly the anthraquinone glycosides and the astringent components.

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Uses1. It is used mainly in the form of an ointment in the treatment and cure of chronic eczema, psoriasis as a potent keratolytic agent.2. It is also used as a purgative.

__________________________________________________3. Cascara sagrada(Cascara bark)

Cascara

sagrada is the dried bark of Rhamanus purshiana(Rhamnaceae)Chemical Constituents The cascara sagrada bark is found to contain two major types of anthracene compounds, namely:(a) Normal O-Glycosides These are based on emodin like structures and constitute about

10 to

20% of the total glycosides, and

(b)

Aloin

-like C-Glycosides These comprise of about 80 to 90% of the total glycosides.

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The main active constituents are four glycosides usually designed as Cascarosides A, B, C and D.

cascarosides A and B are solely based on optical isomers of barbaloin ; whereas cascarosides C and D on optical isomers of

deoxybarbaloin

.

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4. Frangula(Buckthorn bark)النبق المسهلRhamnus

frangula(Rhamnaceae)consists of the two important glycosides Frangulins A and B, which were

initially thought

to be isomeric compounds.Uses: It is mostly used as a cathartic.____________________________________5. Senna: (Senna leaf)Biological Sources:

Senna

is the dried

leaves of

Cassia

senna

(

Alexandria

senna

), or of

Cassia

angustifolia

Vahl

(Indian or

Tinnevelley

Senna

) belonging to

the family

Leguminoseae

Chemical Constituents

The principle active constituents of

senna

are four

sennosides

A, B, C and D

.

Uses:

1. It is mostly used as a cathartic.

2. The inherent action of

senna

is associated with appreciable griping , and therefore, it is generally dispensed along with carminatives so as to counteract the undesired effect.

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Saponin Glycosides(a) They produce foam in aqueous solution, and

(b) They cause haemolysis of Red Blood Cells (RBC).(c) they possess a bitter and acrid taste, besides causing irritation to mucous membranes.

(d

) They are mostly soluble in alcohol and water, but insoluble in non-polar organic solventslike benzene, n-hexane.(E ) The aglycone of the saponin glycosides are collectively known as sapogenins.The harmful and poisonous sapogenine/

saponins

are

aften

referred to as

sapotoxins

.

2

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Based on the nature of the ‘aglycone’ residue present in the saponin glycosides, they are broadly classified into the following two categories, namely:(i) Tetracyclic triterpenoid

saponins (or Steroidal saponins), and(ii) Pentacyclic triterpenoid

saponins

._______________________________________________However, from a commercial angle the steroidal saponins occupy a very important position in the therapeutic purposes which is evidenced by the following examples, such as: usedas raw material for the synthesis of a number of medicinally potent steroids e.g., vitamin D, sex hormones—like testosterone, progesterone, estradiol etc.,

cardiac glycosides

e.g.,

digoxin,

digitoxin

;

corticosteroids

e.g., cortisone acetate,

aldosterone;

oral

contraceptives

e.g

.,

mestranol

,

norethisterone

; and

diuretic steroid

e.g., spironolactone

.

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A. Dioscorea: (Rheumatism root)Biological Source :It essentially comprises of the dried tubers of Dioscorea

delitoidea (Dioscoreaceae)Chemical Constituents The major active constituent of dioscorea

is

diosgenin usually present in the range of 4-6%. Diosgenin is the aglycone of saponoin dioscin. Uses1. Dioscorea is mostly employed in the treatment of rheumatic arthritis.2. Dioscorea

has a

good effect as

a commercial product because of its high content

of

diosgenin

, which in turn is invariably employed as a starting material for the synthesis of

an

important therapeutic drugs, for instance: sex-hormones, oral contraceptives and

several corticosteroids

.

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B. Shatavari : Shatamuli.Asparagus racemosus (

Liliaceae)Chemical Constitutents The shatavari contains four steriodal saponins

usually designated

as shatavarin I-IV present collectively to the extent of 0.2%; however, shatavarin I is the major glycoside present.The a glycon called(sarsasapogenine)Uses1. The roots are employed mostly as galactogogue to promote the flow of milk.2.

The roots are extensively employed as a medicinal oil for the control and management of

nervous disorders

and rheumatism.

3

. It is

used both in threatened

abortion

and

safe delivery

because of

its

distinct

uterine blocking activity

.

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Pentacyclic Triterpenoid Saponins:A. Ginseng(Panax)

Ginseng is the dried root of :Panax ginseng(Korean Ginseng); Panax japonica (Japanese Ginseng); Panax

notoginseng (Indian Ginseng) all to Araliaceae.Chemicals Constitutents Ginseng chiefly comprises of a complex mixture of triterpenoid saponins which may be either a steroidal triterpene or a pentacyclic related to oleonic acid. However,these

glyscosides

have been classified into three major heads, namely:

(a)

Ginsenosides

,

(b)

Panaxosides

, and

(c)

Chikusetsu

Saponins

.

Slide17

In all, about 13 ginsenosides have been isolated and identified. panaxosides undergo decomposition yielding oleanolic acid, panaxadiol and

panaxatriol

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Uses1. In the Chinese system of medicine ginseng used as a general tonic, carminative and diuretic activities.2. It also possesses adaptogenic

(antistress) properties and is found to exert positive action on the metabolism, the endocrine system and the central nervous system.3. In the orient ginseng is used abundantly in the treatment of anaemia, diabetes, insomnia,

and

specifically to cure sexual impotence.4. It is found to enhance the natural resistance (i.e., non-specific resistance) and increases the ability to overcome both exhaustion or illness to a great extent.

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B. Liquorice(Glycyrrhiza)Glycyrrhiza glabra

( Leguminosae)Glycyrrhiza has been derived from the Greek origin (sweet root); and glabra (smooth)

Chemical Constituents

Glycyrrhiza (liquorice) comprises of a saponin like glycoside known as glycyrrhizin (or glycyrrhizic acid) as shown below:Glycyrrhizin is found to be 50 times as sweet as sugar. Glycyrrhizin upon hydrolysis loses its sweet taste and gives rise to the aglycone glycyrrhetinic acid (glycyrrhetic acid) together with two moles

of

glucuronic

acid.

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Uses1. Glycyrrhiza has demulscent and expectorant properties.2. It is used as a masking agent for bitter drugs in pharmaceutical formulations, such as:

quinine, aloe..3. Ammoniated glycyrrhiza is employed as a flavouring agent in pharmaceuticals

and confectionary

.4. The inherent surfuctant activity due to the presence of saponins helps to facilitate the absorption of poorly absorbed drugs, for instance: anthraquinone glycosides.5. The presence of glycyrrhetinic acid exert mineralocorticoid activity and hence it is used in the treatment of inflamations, and rheumatoid arthritis .

6

.

Liquorice

liquid extract is used in the treatment of peptic ulcer.

7

.

In Europe the

glycyrrhetic

acid is employed exclusively in dermatological formulations for

its remarkable

antiinflammatory

properties.

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C. Bacopa(Brahmi)fresh stems and the fresh leaves of Bacopa monnieri

(Secrophulariaceae)Chemical Constituents The leaves contain saponin glycosides known as bacoside A and

bacoside

B which on acid hydrolysis give rise to triterpenoid aglycone termed as bacogenin A and bacogenin B respectively. Uses1. It is used in the treatment of insanity and epilepsy2. It is also employed as a potent nervetonic, cardiotonic and diuretic

3. It is mostly used in the treatment of asthma and

as

a mild laxative.

Slide22

D. Quillaja(Quillaia bark)Quillaja saponaria

(Rosaceae)Chemical Constituents: Quillaja (quillaia

) contains 9-10% of

colourless amorphous triterpenoid saponin glycosides. The acrid and astringent taste of the bark is due to the presence of quillaia sapotoxin( a glycone).Uses1.It is employed for making shampoo liquid.2.

It is mostly used as a foam producer.

3.

It is generally employed as an emulsifying agent.

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Aldehyde GlycosidesVanilla pod is the most example of a naturally occurring plant that contains an aldehyde glycoside

e.g.; glucovanillin; and cinnamon bark is another important example which contains cinnamic aldehyde.____________________________________Vanilla(Vanilla beans)

Vanilla consists of the cured, full

grown fruit of Vanilla planifolia(Orchidaceae)Chemical Constituents The fruits of vanilla pod contains between 2 to 2.75% vanillin, which is essentially present in the form of glucovanillin .

3

Slide24

It also contains another glycoside known as glucovanilline alcohol, which upon hydrolysis yields vanillic alcohol and glucose. The vanillic alcohol on oxidation gives vanillin.Uses

It is mostly used as a pharmaceutical aid for flavouring various liquid preparations.

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Thioglycosides(SulphuratedGlycosides) or (Glucosinolate Compounds) or

(Isothiocyanate Glycosides)1. Black Mustard(Brown Mustard)

Brassica

nigra (Cruciferae.)It contains thioglycoside(sinigrin)also called allyl glucosinolate

4

Slide26

Uses A paste of black mustard seed is mostly employed in the form of plaster or as a rubefacient and counter irritant.2. In higher doses, when administered internally, it acts as an emetic

.____________________________________________________2. White Mustard

These are the dried ripe seeds of

Brassica alba (Cruciferae)The paste of white mustard seed used as counter irritants and rubefacients

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Cyanogenetic Glycosides(cyanophore glycosides)

The cyanogenetic glycosides are named so because they yield either hydrocyanic acid upon hydrolysis or they essesntially possess a hydrocyanic acid in the

aglycone

moiety._____________________________________1.Bitter Almond(Amygdala amara)Bitter almond comprises of the dried ripe kernels of Prunus amygdalus ( Rosaceae)Chemcial

Constituent

Bitter almond contains a

colourless

crystalline

cyanogenetic

bitter glycoside

commonly termed as amygdalin present to the extent of 1-3%.

5

Slide29

The enzymatic hydrolysis of amygdalin takes place in the following three steps, namely:(a) The enzyme amygdalase helps to cleave the glycoside amygdalin first into one mole each

of glucose and prunasin (or mandelonitrile glucoside),(b) The enzyme prunase

helps to liberate the second molecule of glucose with the formation of the aglycone mandelonitrile (or benzaldehyde cyanohydrin), and(c) The enzyme hydroxynitrilase helps to break down the mandelonitrile into one mole each of benzaldehyde and hydrocyanic acid.

Slide30

Uses

1. Bitter almonds are employed as sedative due to HCN content.

2. The fixed oil of bitter almond finds its use as

demulscent in skin-lotion.

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2 .Wild Cherry Bark(Wild Black Cherry)dried bark of Prunus serotina (

Rosaceae).Uses1. The syrup of wild cherry is mostly employed as a flavoured vehicle in cough syrup.

2. It is also used as a sedative expectorant.

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3.Linseed(Flax seed)dried fully ripe seeds of Linum usitatissimum(Liliaceae)

Chemical ConstituentsThe ripe seeds of linseed contain small quantitites of a cyanogenetic glycosides known as

linamarin

. linamarin evolved HCN with linseed meal only but not with emulsin. Linamarin upon enzymatic hydrolysis yields HCN which actualy renders the seeds highly poisonous.Uses It is employed in the treatment of scabies and other skin disease in combination with sulphur.