GLYCOSIDES & Terpenoids - PowerPoint Presentation

Slide1

GLYCOSIDES&Terpenoids

6

th

lecture/3

rd

stage/1

st

semester

Slide2

A. DIGITALIS1. Digitalis purpurea

:

(Foxglove; Purple

foxglove)

Digitalis

purpurea

(

Scrophulariaceae

)

[ The word

purpurea

has been derived from the purple

colour

of flowers].

It has been reported that digitalis essentially contains three important

primary

glycosides

namely:

Purpurea

glycoside A,

Purpurea

glycoside B,

and

Purpurea

glycoside C

, which upon

hydrolysis give

rise to

digitoxin

,

gitoxin

and

gitalin

respectively.

These

secondary

glcosides

on further

hydrolysis yields

noncarbohydrate

moieties (called

aglycones

or

genins

)

digitoxigenin

,

gitoxigenin

and

gitaligenin

respectively.

Slide3

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Uses1. Digitalis enhances the force of contraction of heart muscle and increase cardiac output. Digitalis

together with its various marketed preparations

are employed profusely as vital

cardiotonics

in the management and control of different kinds

of congestive

heart failure, atrial flutter, atrial fibrillation, supraventricular tachycardia and

premature extra

systoles.

2

. Digitalis has a tendency to exert an overall cumulative effect in the body, and hence it

gets eliminated

rather gradually. Therefore, it is extremely important to monitor

the dosage regimen by

a physician

whether he

relies on branded products or natural drug preparations

eg

.,

Digoxin injection and tablets(

Lanoxin

).

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2. Digitalis Lanata:White Foxglove leaf

Digitalis

lanata

(

Scrophulariaceae

)

It contains

Lanatoside A, Lanatoside B, and Lanatoside C

.

Digoxin derived

from

Lanatoside C

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3. Digitalis lutea:Straw

Foxglove

Digitalis

lutea

(

Scrophulariaceae

)

Uses

1. It is used as a common substitute for the official drug.

2. It is potent as

D.

purpurea

.

3. It is mostly used for the same purpose as that of

D.

purpurea

.

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4. Digitalis

Thapsi

:(Spanish Foxglove)

Digitalis

thapsi

(

Scrophulariaceae

)

Uses

Its therapeutic efficacy is almost 1.25 to 3 times more potent than

D

.

purpurea

and its

actions are similar.

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Digoxin (

Lanoxin

) is a purified digitalis preparation

from

D.

lanata

and represents the most widely used

digitalis glycoside. This wide use is primarily a result of its

fast onset and short half-life. Position 3 of the steroid is

substituted with

three

digitoxose

residues that, when removed,

provide a

genin

or

aglycone

steroid that is still capable of

receptor binding

but with altered pharmacokinetics.

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B. SquillIt contains two glycosides in their purest

form, namely:

Scillaren

A

and

Scillaren B

. These two naturally

occuring

glyosides

are

usually present

in the crude drug in the ratio 2:1 (i.e., 2 parts of

Scillaren

A and 1 part of

Scillaren

B).

Generally, the

squill

is available in three varieties, namely:

(a) European

Squill

(b) Indian

Squill

, and

(c) Red

Squill

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European

Squill

:(

Sea

onion, White

Squill

)

Scilla

maritima

(

Liliaceae

)

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Chemical Constituents Squill has the following glycosides:Glucoscillaren

A =

Scillarenin

+

Rhamnose

+ Glucose +

Glucose.

Scillaren

A =

Scillarenin + Rhamnose + Glucose.Proscillaridin A = Scillarenin + Rhamnose.

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Uses1. It is a potent cardiotonic without any cumulative effect (unlike Digitalis).

2. It is mostly employed in small doses as an effective expectorant specially in chronic bronchitis.

3. It causes emesis in relatively higher doses.

4. The

squill

glycosides usually

produce

diuresis.

5.

squill glycosides possess high therapeutic index and rapid elimination they invariably maintain compensation in such patients where a prolonged treatment is required.

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b) Indian Squill:ScillaUrginea

indica

(

Liliaceae

)

The two major cardiac glycosides present in the drug are

Scillaren

A and

Scillaren B.Uses1. It is largely employed as a cardiotonic .2. It is used as a very effective expectorant both in asthma and chronic bronchitis.

3. It possesses anticancer activity against human carcinoma .Disadvantage: It is in no way a perfect replacement for Digitalis since it possesses not only irritant effect but also is very poorly absorbed systemically.

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c) Red Squill: It is the red variety of European squill.

Urginea

maritima

(

Liliaceae

.)

Slide12

C. StrophanthusStrophanthus

hispidus

(

Apocyanaceae

)

Slide13

In K-Strophanthoside , the aglycone is known as

strophanthidin

that

has the following characteristic

features:

(a) Three—OH moieties at positions C-3, C-5 and C-14.

(b) An

aldehydic

(—CHO) function is present at C-10 which being an essential requirement.

(c) At C-17 an unsaturated 5-membered lactone ring, and(d) At C-3 an ‘O’ atom forms a bridge to the sugar compotent(s) essentially comprising of cymarose, beta-D-glucose and alpha -D-glucose.

Acidic hydrolysis of K-strophanthoside gives rise to the aglycone strophanthidin along with a triose sugar known as strophanthotriose that comprise of one mole of cymarose and two moles ofglucose.

Uses

It is used intravenously for treating emergency cardiac conditions. However, orally

strophanthin

is not so active.

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Bitter Glycosides1.

Picrorhiza

:(

Indian

Gentian)

Picrorhiza

kurroa

(

Scrophulariaceae)Chemical Constituents: The therapeutically potent constituents of the drug essentially comprises of three vital bitter glycosides, namely: Picroside I, Picroside II and

Kutkoside.Uses1. It is mostly employed as a vital tonic2. It is also used as a febrifuge.3. It exerts its action as a laxative.

4. It also finds its usefulness in the treatment of jaundice.

5. Its

alcohlic

extract

exhibits

remarkable

antibacterial effect.

10

Slide15

2. Chirata: Bitter stickSwerlia

chirata

(

Gentianaceae)

Chemical Constituents

:

amarogentin and chiratin.Uses1. It is invariably used as a bitter tonic.2. It also finds its use as a febrifuge.3. It is employed in dyspepsia.

4. It has been recommended as a diuretic and in epilepsy.5. Industrially, it is extensively used in dyeing cotton cloth.

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Miscellaneous Glycosides

Steroidal

Alkaloidal

Glycosides:

Rubijervine

Solanum

lycopersicum (Solanaceae) (Tomato)Used as antifungalb.

SolanineSolanum tuberosum (Solanaceae) (Potato)

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Slide17

2.Antibiotic Glycosides:Streptomycin is the example of an antibiotic glycosides produced by the soil Actinomycete

.

Streptomyces

griseus

(

Actinomycetaceae

).

It is

usually formed by the combination of the genin Streptidine a nitrogen containing cyclohexane derivative and Stre ptobiosamine a disaccharide representing two-thirds of the streptomycin

molecule through a glycosidic linkage .

Slide18

3. Nucleosides (Nucleic Acids)These naturally occurring substances are of prime biological importance and essentially possess three

vital components namely:

firstly,

a sugar moiety e.g.; ribose or 2-desoxyribose;

secondly

,

a purine or pyrimidine base e.g.; adenine, guanine and cytosine; and

thirdly,

a phosphoric acid

. A base-sugar unit is known as a nucleoside, whereas a base-sugar phosphoric acid unit isknown as nucleotide.

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TerpenoidsA plethora of naturally occurring plant products have been found to be related wherein they

are comprised

of one or more units of isoprene (C5H8)-a hydrocarbon

:

In

general,

terpenoids

, may be defined as natural products whose structures are considered

to be

divided into several isoprene units; therefore, these compounds are termed asisoprenoids.

Terpenoids are broadly classified on the basis of the number of isoprene units into:

Slide20

(a) Monoterpenoids:two isoprene units and have the molecular formula C10H16.(b)

Sesquiterpenoids

:

three

isoprene units and have the

molecular formula C15H24.

(c)

Diterpenoids

:

four isoprene units and have the molecular formula C20H32.(d) Triterpenoids: six isoprene units and have the molecular formula C30H48.(e) Tetraterpenoids

(or Carotenoids): :eight isoprene units and have the molecular formula C40H64.

Slide21

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CLASSIFICATION(i) Monoterpenoids

(ii)

Sesquiterpenoids

(iii)

Diterpenoids

(iv)

Triterpenoids

(v)

Tetraterpenoids

and Carotenoids(vi) Volatile Oils (or Essential Oils)(vii) Resins and Resin Combinations(viii) Oleoresins(ix) Oleo-Gum-Resins

(x) Balsams

Slide23

Resins and Resin CombinationsResins

, in general, are amorphous solid or semisolid substances that are invariably water

insoluble but

mostly soluble in alcohol or other organic solvents

.

Physical

Properties of

Resins:

A

re hard, transparent or translucent brittle materials.They are invariably heavier than water having the specific gravity ranging from 0.9-1.25.

On being heated at a relatively low temperature resins first get softened and ultimately melt by forming a sticky massive fluid, without undergoing any decomposition or volatilization.

Slide24

4.On being heated in the air i.e., in the presence of oxygen, resins usually burn readily with a smoky flame by virtue of the presence of a large number of C-atoms in their structure.5.They are practically insoluble in water, but frequently soluble in ethanol, volatile oils, fixed

oils, chloral

hydrate and non-polar organic solvents e.g., benzene, n-hexane and petroleum ether

.

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Chemical Properties of

Resins:

1.Resins

, in general, are enriched with carbon,

and contain a few oxygen in their respective molecules.2. Majority of them undergo slow atmospheric oxidation and their colour

get darkened with impaired solubility.3. Resins are found to be a mixture of numerous compounds rather than a single pure chemical entity.

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Chemical Composition of Resins:(i) Resin Acids.

(ii) Resin Esters and their Decomposition Products i.e., Resin Alcohols (

Resinols

) and Resin

Phenols (

Resinotannols

).

(iii)

Resenes

i.e., the chemical inert compounds.