Lecture 31 - Hydrolysable Tannins [Compatibility Mode]

8/3/2019 Lecture 31 - Hydrolysable Tannins [Compatibility Mode]

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TANNINSTANNINS--IIII

M. Ahsan Khalid,M. Ahsan Khalid, B.PharmB.Pharm, Pharm. D, Pharm. DM.PhilM.Phil Scholar (RIPS/RIU)Scholar (RIPS/RIU)

HIPSHIPS--HUKICHUKIC

PHARM. DChemical Pharmacognosy- I

Lecture 31May 18th, 2011


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3 major classes of tannins are:3 major classes of tannins are:

Hydrolysable tanninsHydrolysable tannins on heating withon heating with

hydrochloric orhydrochloric or sulphuricsulphuric acids yieldacids yield gallicgallic ororellagicellagic acidsacids EgEg-- Turkish galls,Turkish galls, hemamalishemamalis,,pomegranatpomegranat

NonNon--hydrolysable tanninshydrolysable tannins on heating withon heating with

hydrochloric acid yieldhydrochloric acid yield phlobaphenesphlobaphenes likelikephloroglucinolphloroglucinol EgEg-- black catechu, pale catechu,black catechu, pale catechu,kinoskinos

Pseudo tanninsPseudo tannins are low molecular weightare low molecular weight

compounds associated with other compounds.compounds associated with other compounds.They do not answer gold beater skin test unlikeThey do not answer gold beater skin test unlikehydrolysable and condensed tannins.hydrolysable and condensed tannins. EgEg-- tea,tea,coffee They havecoffee They have catechinscatechins which give rise towhich give rise to

the peculiarthe peculiar odourodour..


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Classification of TanninsClassification of Tannins

In higher plants, two groups of tannins areIn higher plants, two groups of tannins are

generally distinguished, which differ bygenerally distinguished, which differ by

their structure, as well as their biogenictheir structure, as well as their biogenicoriginorigin hydrolysablehydrolysable tannins andtannins and

condensedcondensed tannins.tannins.

Hydrolysable TanninsHydrolysable Tannins:: EllagitanninsEllagitannins

GallotanninsGallotannins


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Hydrolysable TanninsHydrolysable Tannins

Hydrolyzable tannins are hydrolyzed byHydrolyzable tannins are hydrolyzed by

weak acidsweak acids or weakor weak basesbases to produceto produce

carbohydrate and phenolic acids.carbohydrate and phenolic acids.

Examples of gallotannins are theExamples of gallotannins are the gallicgallic

acidacid esters of glucose in tannic acid,esters of glucose in tannic acid,

(found in leaves and bark of many plant(found in leaves and bark of many plantspecies)species)


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HydrolysableHydrolysable TanninsTannins They may beThey may be hydrolyzed by acidshydrolyzed by acids oror enzymesenzymes such assuch as

tannasetannase, (products being sugar and, (products being sugar and phenolicphenolic acids).acids). Formed by severalFormed by several phenolicphenolic acids which are united byacids which are united by

ester linkages to a central sugar (glucose) molecule.ester linkages to a central sugar (glucose) molecule.

Hydrolysable tannins are thereforeHydrolysable tannins are therefore esters of a sugar andesters of a sugar andphenolicphenolic acid moleculesacid molecules..

TheThe phenolicphenolic acid isacid is

in the case ofin the case of gallotanninsgallotanninsgallicgallic acidacid

in the case ofin the case of ellagiellagi--tanninstannins hexahydroxydiphenichexahydroxydiphenicacid (acid (HHDPHHDP) and its) and its oxidized derivativesoxidized derivatives((dehydrohexahydroxydiphenicdehydrohexahydroxydiphenic acid).acid).

EllagitanninsEllagitannins are found in Herb Robert (Geraniumare found in Herb Robert (Geraniumspecies,species, MeadowsweedMeadowsweed and Oak bark).and Oak bark).


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Egs of Hydrolysable TanninsEgs of Hydrolysable Tannins

Gallotannins:Gallotannins: rhubarb, cloves, red roserhubarb, cloves, red rosepetals, bearberry leaves, Chinese galls,petals, bearberry leaves, Chinese galls,Turkish galls, hamamelis, chestnut andTurkish galls, hamamelis, chestnut and

maplemaple

EllagitanninsEllagitannins: pomegranate rind,: pomegranate rind,

pomegranate bark, eucalyptus leaves,pomegranate bark, eucalyptus leaves,some Australian kinos, chestnutsome Australian kinos, chestnut(Castanea spp), and oak bark.(Castanea spp), and oak bark.


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EllagitanninsEllagitannins

With more than 500 natural products

characterized so far, ellagitannins are thelargest group of known tannins.

Ellagitannins are formed from the

gallotannins by the oxidative coupling of at

least two galloyl units.


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Gallotannins are the simplest hydrolysable

tannins, containing a polyphenolic and a

polyol residue. Polyol: alcohol with multiple hydroxyl

groups.

Most of the gallotannins isolated from

plants contain a polyol residue derivedfrom D-glucose.


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HydrolyzableHydrolyzable TANNINTANNINCONTAINING HERBSCONTAINING HERBS


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Turkish GallsTurkish Galls

Definition:Definition: Turkish gallsTurkish galls arearevegetable growths formed on thevegetable growths formed on theyoung twigs of the dyers oak,young twigs of the dyers oak,QuercusQuercus infectoriainfectoria((FagaceaeFagaceae).).

TheyThey result from the decomposition ofresult from the decomposition ofthe eggs of the gallthe eggs of the gall--waspwasp

AdleriaAdleria gallaetinctoriaegallaetinctoriae..

If the galls are not collected andIf the galls are not collected anddried, the mature insect bores outdried, the mature insect bores outof the gall and escapes.of the gall and escapes.


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Turkish Galls: CollectionTurkish Galls: CollectionGalls are collected by peasants of Turkey and SyriaGalls are collected by peasants of Turkey and Syria..

In the summer gall wasps lay eggs on the twigs.In the summer gall wasps lay eggs on the twigs.

It penetrates the soft epidermis of the plant & soonIt penetrates the soft epidermis of the plant & soonforms a larvae.forms a larvae.

This larvae develops into galls.This larvae develops into galls.

Ideally galls should be collected before the matureIdeally galls should be collected before the matureinsect comes out.insect comes out.

AfterAfter collection they are graded according to colour intcollection they are graded according to colour int3 grades: blue, green and white.3 grades: blue, green and white.

Colour changes occur due to enzymatic secretions ofColour changes occur due to enzymatic secretions of

insect.insect.


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Turkish gallsTurkish galls -- ConstituentsConstituents

5050 70% tannin70% tannin gallotannicgallotannicacid.acid.

Tannic acid:Tannic acid: hydrolysablehydrolysabletannin (consisting oftannin (consisting of gallicgallicacidacid andand glucoseglucose).).

Gallic acidGallic acid

EllagicEllagic acidacid

SitosterolSitosterol

StarchStarch

Calcium oxalateCalcium oxalate

SyringicSyringic acid (CNSacid (CNS--activeactivecomponent)component)


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Extraction of tannic acid:Extraction of tannic acid:

A mixture of alcoholA mixture of alcohol--ether is added toether is added to

galls.galls.

When water is added to this extract theWhen water is added to this extract thetannic acid enters the alcohol layer.tannic acid enters the alcohol layer.

The ether layer can be discarded.The ether layer can be discarded.

After precipitation with a nonAfter precipitation with a non--polar solventpolar solventit occurs as a white shiny powder.it occurs as a white shiny powder.


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Turkish GallsTurkish Galls

Uses & Allied DrugsUses & Allied Drugs UsesUses

Used as a source ofUsed as a source oftannic acid.tannic acid.

Tannic acid is used asTannic acid is used asan astringent andan astringent andstyptic.styptic.

Used for tanning andUsed for tanning anddyeing.dyeing.

Ink manufacturing.Ink manufacturing.

Allied DrugsAllied Drugs

Chinese andChinese andJapanese GallsJapanese Galls

Hungarian GallsHungarian Galls


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Pomegranate RindPomegranate Rind

Definition:Definition:PomegranatePomegranateconsists of the fruitconsists of the fruit

pericarp, or the stempericarp, or the stemand bark ofand bark of PunicaPunicagranatum.granatum.


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Punica granatumPunica granatum-- PunicaceaePunicaceae

History: MentionedHistory: Mentionedin Bible and Quran.in Bible and Quran.

Used as an AncientUsed as an Ancient

Medicine (Indian andMedicine (Indian andArab physicians).Arab physicians).


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Active Constituents:Active Constituents: PunicaPunica

Fruit:Fruit:Gallo/ellagitanninsGallo/ellagitannins

MainlyMainly punicalinpunicalin andand

punicalaginpunicalagin

Alkaloids are presentAlkaloids are presentin the bark, leavesin the bark, leaves

and young fruit. (noand young fruit. (noalkaloids are presentalkaloids are presentin the rind).in the rind).


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Pomegranate: Actions & UsesPomegranate: Actions & Uses

Therapeutic category:Therapeutic category:AntiAnti--diarrhoeal, antidiarrhoeal, anti--helminthic.helminthic.

Uses:Uses: Bark is traditionallyBark is traditionallyused to treat worms.used to treat worms.

Dried fruit rind or fruitDried fruit rind or fruitpulp is used to treatpulp is used to treatdiarrhoea.diarrhoea.

A tea is normally madeA tea is normally madewith honey (bitter taste).with honey (bitter taste).


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Punica granatumPunica granatum: Pomegranate: Pomegranate Pharmacological Effects:Pharmacological Effects:AntiAnti--diarrhoeal effectdiarrhoeal effect

TanninsTannins

AntiAnti--helminthic effecthelminthic effect

alkaloidsalkaloidsThey interact strongly withThey interact strongly with

the nicotinic Acetylcholinethe nicotinic Acetylcholinereceptors: causereceptors: causetapeworms to lose theirtapeworms to lose theirgrip, and are expelledgrip, and are expelledfrom the body.from the body.

NOTE:NOTE: Alkaloids are toxicAlkaloids are toxicand self medication mayand self medication maybe dangerous.be dangerous.


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Punica granatumPunica granatumand Alzheimersand Alzheimers

Research conducted onResearch conducted onmice that were givenmice that were givenpomegranate juice,pomegranate juice,experienced 50% lessexperienced 50% less

degeneration of braindegeneration of braincells, compared to theircells, compared to theircounterparts, who drankcounterparts, who drankonly sweetened water.only sweetened water.

This indicates thatThis indicates thatpomegranate juice maypomegranate juice mayhelp cut risk ofhelp cut risk ofAlzheimers disease.Alzheimers disease.


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Punica granatum &Punica granatum & CV HealthCV Health Tests showed thatTests showed that

pomegranate juicepomegranate juicereduced the effectsreduced the effectsof stress on humanof stress on humanblood vessel cellsblood vessel cellsby stimulating theby stimulating theproduction of nitricproduction of nitric

oxide. This chemicaloxide. This chemicalis thought to helpis thought to helpkeep arteries openkeep arteries openand keep bloodand keep bloodflowing.flowing.

Additional researchAdditional researchshows pomegranateshows pomegranatejuice can bothjuice can bothreverse and preventreverse and preventatherosclerosis.atherosclerosis.

Researchers say theResearchers say the

beneficial effects ofbeneficial effects ofpomegranate juicepomegranate juiceon hardening of theon hardening of thearteries are likelyarteries are likelylargely due to itslargely due to itshigh antioxidanthigh antioxidant

content. The studycontent. The studyshowed that theshowed that theantioxidant level inantioxidant level inpomegranate juicepomegranate juicewas higher than thatwas higher than thatfound in other fruitfound in other fruit

juices, includingjuices, includingblueberry, cranberry,blueberry, cranberry,orange, and evenorange, and evenred wine.red wine.


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PunicaPunica granatumgranatum& Cancer& Cancer Drinking 8 ounces ofDrinking 8 ounces of

pomegranate juice daily canpomegranate juice daily cansuppresssuppress prostate cancerprostate canceractivity in men with recurrentactivity in men with recurrentprostate cancer, according to aprostate cancer, according to astudy presented at the annualstudy presented at the annualmeeting of the Americanmeeting of the American

Urological Association in SanUrological Association in SanAntonio.Antonio.

A recent study at the UniversityA recent study at the Universityof Wisconsinof WisconsinMadison using aMadison using a

mouse model shows thatmouse model shows thatconsuming pomegranates couldconsuming pomegranates couldpotentially help reduce thepotentially help reduce thegrowth and spread of lunggrowth and spread of lungcancer cells or even preventcancer cells or even prevent

lung cancerlung cancer from developing.from developing.

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Lecture 31 - Hydrolysable Tannins [Compatibility Mode]

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