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TheBindingAbilityandInclusionComplexationBehaviorofCurcuminwithNaturalα ,β ,γ CyclodextrinsandOrganoselenium BridgedBis(β cyclodextrin)sQIAi di,LILiandLIUYu (DepartmentofChemistry,NankaiUniversity,Tianjin300071,China)Abstract:Aim Toinvestigatequantitativelythebindingabilityandinclusioncomplexationbehaviorofcurcuminwithnaturalα ,β ,γ cyclodextrins(1-3)andaseriesoforganoselenium bridgedbis(β cyclodextrin)swithsimplespacer(4-6).Methods ThespectrophotometrictitrationshavebeenperformedinKCl HClbuffersolution(pH=2.0)at25℃tocalculatethecomplexstabilityconstants(Ks)andGibbsfreeenergychanges(ΔG°)forthestoichiometric1∶1inclusioncomplexationof1-6withcurcumin.Results Thebindingabilityofβ cyclodextrinforinclusioncomplexationwithguestcurcuminishigherthanthatofα andγ cyclodextrins.Ascomparedwithparentβ cyclodextrin,theorganoseleniumbridgedbis(β cyclodextrin)stetheredbysomefunctionalgroupscanfurtherenhancetheoriginalmolecularbindingabilitythroughcooperativebindingofonecurcuminmoleculeinthecloselylocatedtwocyclodextrincavities,showingtheenhancedbindingabilitiesofparentβ cyclodextrinbyafactor2.8-17.1.Conclusion Size shapefitandhydrophobicinteractionbetweenhostcyclodextrinsandguestcurcuminmoleculearetheimportantfactorsaffectingthebindingabilityandinclusioncomplex ationbehaviorofthesecyclodextrins1-6.Keywords:curcumin;modifiedcyclodextrin;molecularrecognition;inclusioncomplexationCLCnumber:R913;O648.2 Documentcode:A ArticleID:1003-1057(2003)01-015-06IntroductionCurcumin,theextractionofanaturalproductcurcu ma,hasbactericidalactionandmayminimizeoxidativedamage.Itsantioxidantmechanism[1]andpharmacologicaleffectsforanti cancer[2]arebeingresearchedinrecentyears.Curcuminispracticallyinsolubleinaqueousmedia,butdissolvedinorganicsolvents.Sincetheuseoforganicsolventsincertaincaseneedstobeavoided,theincreaseofitssolubilityinaqueoussolutionmaybeimportant.Cyclicoligosaccharides,composedofsixtoeightlinkedD glucopyranoseunitsformingtruncatedconicalstructures,arenamedasα ,β ,andγ cyclodextrinsre spectively.Possessinghydrophobiccavitiesofdifferentsize,naturalandmodifiedcyclodextrinscanbindvariousmoleculesofrespectivesizeandshapetoforminclusionReceiveddate:December20,2002Biography:QIAi di,OnleavefromTianjinCollegeofTraditionalChi neseMedicine Correspondingauthor:Tel+86 022 23503625E <A href="mailto:mailyuliu@public.tpt.tj.cncomplexesinaqueoussolution,whichwasuseddistantlyinscienceandtechnologyfield[3" target="_blank" >mailyuliu@public.tpt.tj.cncomplexesinaqueoussolution,whichwasuseddistantlyinscienceandtechnologyfield[3</A> 4]especiallyformolecularrecognitionwithaseriesofguestmolecules,suchasdye s[5 7],alcohols[8],andaminoacid[9 11]etc,andwhichcanalsoenablecyclodextrinstobesuccessfullyusedasdrugcarriers[12]forincreasingtheaqueoussolubilityoforganicmolecules,suchascurcumin.Ontheotherhand,thelowaqueoussolubilityofnaturalcyclodextrins,particularlythatofβ cyclodextrin,restrictstheiruseofdrugcarriers.Therefore,aseriesofcyclodextrinderivativesofgoodaqueoussolubilityhavebeendesignedandsynthesizedinordertoresolvethisproblem.Recently,thestabilizationandsolubilizationoftheinclusioncomplexformedbythecurcuminwithcyclodextrinshavebeenstudiedanddis cussedbySzenteetal[13],givingthesignificantresults.Unfortunately,thestudiesaboutbindingabilityandinclu sioncomplexationbehaviorsofcurcuminmoleculewithcy clodextrinsandtheirderivativesarestillrare.Wehavere centlyshownthattheorganoseleniumbridgedbis(β cyclo dextrin)spossessingtheexcellentaqueoussolubilityandthelowtoxicityformmorestablecomplexeswithdyemole culesthannativeβ cyclodextrin[14 16].51JournalofChinesePharmaceuticalSciences2003,12(1) |
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