Glycosides.ppt

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1、GlycosidesDefinition:Organicnaturalcompoundspresentinalotofplantsandsomeanimals,thesecompoundsuponhydrolysisgiveoneormoresugars(glycone)β_formandnonsugar(aglycone)orcalledgenin.Solubility:glycosidesarewatersolublecompoundsandinsolubleintheorganicsolvents.Glyconepart:watersol

2、uble,insolubleintheorganicsolvents.Aglyconepart:waterinsoluble,solubleintheorganicsolvents.Someglycosidessolubleinalcohol.Separationbetweenglycosidesparts:Glycosidesglycone+aglycone+HCLG+A+salt+H2O(H2O+G)+A(H2O+G)+(chloroform+A)WecanseparatethembyusingseparatoryfunnelThebest

3、solventtoextractaglyconeisEthylacetatebecause:A-immiscibleinwater.B-alwayspresentsintheupperlayer.NeutralizationbyUsingalkalineFiltrationchloroformHydrolysis+HCLdilNote:Alcoholandacetonearewatermisciblecompounds,sowecan'tusethemasorganicsolventsforaglyconeseparation.physico-

4、chemicalpropertiesofglycosides(general)Colorless,solid,amorphous,nonvolatile(flavonoid-yellow,anthraquinone-redororange.GivepositivereactionwithMolisch'sandFehling'ssolutiontest(afterhydrolysis).Theyarewatersolublecompounds,insolubleinorganicsolventsMostofthemhavebittertaste

5、(except:populin,glycyrrhizin,stevioside).Cont...Odorlessexceptsaponin(glycyrrhizin).whenaglycosideshasalotofsugarsitssolubilityinwaterdecrease.Glycosideshydrolyzedbyusingmineralacidsandtemperatureorbyusingenzymessuchas:a-EmolsinBitteralmondseeds.b-MyrosinorMyrosinaseblackmus

6、tardseeds.c-Rhamnaseglycosidescontainingrhamnoseassugarpart.Biosynthesisofglycosides(O-glycosides)UTP(UridineTriphoshate)+sugar-1-phoshateUDP-sugar+ppi(Pyrophosphateinorganic).UDP-sugar+acceptor(aglycone)Acceptor-sugar+UDPUridylyltransferaseEnzymeGlycosyltransferaseEnzymeGl

7、ycosyltransferaseEnzymeThefunctionortheroleofglycosidesintheplantorganismConvertingtoxicmaterialstononorlesstoxic.Transferwaterinsolublesubstancesbyusingmonosaccharide.Sourceofenergy(sugarreservoir).Storingharmfulproductssuchasphenol.Regulationforcertainfunctions(growth).Som

8、ehavebeautifulcolours(pollenationprocess).Cont…Someglycosideshaveantibacter