泥鳅Qin_2002_The-Journal-of-Nutritional-Biochemistry
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Protectiveeffectofpolysaccharidefromtheloachontheinvitroandinvivoperoxidativedamageofhepatocyte
ChuanguangQina,b,KaixunHuanga,HuibiXua*aPharmaceuticalInstitute,HuazhongUniversityofScienceandTechnology,430074,Wuhan,P.R.China
bDepartmentofBioengineering,HubeiPolytechnicUniversity,430068,Wuhan,P.R.China
Received13July2001;receivedinrevisedform18February2002;accepted29March2002
AbstractMisgurnusanguillicaudatuspolysaccharide(MAP),atypeofnaturalneutralpolysaccharideoccurringinthemucusofMisgurnusanguillicaudatusC.,wasstudiedforantioxidantbioactivity.ThepreliminaryresearchshowedthatMAPwasabletoremoveO2•,HO⅐,H2O2andotheractivecompoundsofoxygenandsignificantlyprotectedDNAchainsfrombeingdamagedbyhydroxylradicals.Thisantioxidant
bioactivitywasfurtherevaluatedusingthemodelofperoxide-inducedoxidativeinjuryinratprimaryhepatocytesandhepatotoxityinmice.TheresultsdemonstratedthatMAP,attheconcentrationsof0.10ϳ0.40mg/ml,significantlyincreasedtheactivityofSODandGSH-px,butdecreasedtheconsumptionofreducedglutathioneandtheformationofmalondialdehydeinducedbya30-mintreatmentofH2O2(2.0
mmol/L).TheinvivoinvestigationshowedthatoralpretreatmentofMAP(100,200and300mg/kg)for7daysbeforeasingledoseoft-BHP(0.2mmol/kg,ip)significantlyloweredtheserumlevelsofhepaticenzymemarkers(alanineandaspartateaminotransferase)andreducedoxidativeliverinjury.ThehistopathologicalevaluationoftheliverrevealedthatMAPreducedtheincidenceofliverlesionsincludinginflammatory,leukocyteinfiltration,andnecrosisinducedbyt-BHPinmice.Basedontheresultsdescribedabove,aconclusioncanbedrownthatMAPmayplayanimportantroleinthepreventionofoxidativedamageinlivingsystems.©2002ElsevierScienceInc.Allrightsreserved.
Keywords:Misgurnusanguillicaudatuspolysaccharide;loach;liverinjury;lipidperoxidation;hepatoxicity
1.IntroductionThemucuscoatoffishskincontainsavarietyofsecre-tionsfromepidermalgobletcellsandepithelialcells.Thesesecretionshavebeenimplicatedinmanyimportantbiolog-icalfunctions[1].Theloach(Misgurnusanguillicaudatus)haslongbeenemployedastraditionalChinesemedicineinfolkremediesforthetreatmentofhepatitises,osteomyeitis,carbuncles,inflammationsandcancers[2].Somevertebratelectinswerepurifiedfromtheskinmucusoreggoftheloach(Misgurnusanguillicaudatus)andfoundtoinducereleaseofcytotoxinfromfreshmurinebonenarrowcellsormacrophagesandlysetumorcellsbutnotnormalspleencells[3–6].Anovelantimicrobialpeptidenamedmisgurin,whichconsistsof21aminoacidresidues,fromtheloachwasisolatedandidentified[7].Thecarbohydratecomposi-tionsoftheskinmucusofseveralspeciesoffishwasexaminedandfoundthatthesialicacidsinloachconsistedpredominantlyof2-keto-3-deoxy-D-glycero-D-galacto-nononicacid(KDN).Adeaminatedneuraminicacid-con-tainingglycoproteinfromtheskinmucusoftheloach,Mis-gurnusanguillicaudatus,wasisolatedandcharacterized[8].Misgurnusanguillicaudatuspolysaccharide(MAP),akindofneutralfreepolysaccharide,wasextractedfromthemucusoftheloach(Misgurnusanguillicaudatus).Thepre-liminaryresearchshowedthatMAPwasabletoremoveO2•,HO⅐,H2O2andotheractivecompoundsofoxygenandsignificantlyprotectedDNAchainsfrombeingdamagedbyhydroxylradicals[9].ThepresentstudywascarriedtoexaminewhetherMAPcouldprotecttherathepatocytesagainsttheoxidativedamageinducedbyhydroperoxideinvitro.TheprotectiveeffectofMAPagainstinvivoliverinjurycausedbyt-BHPwasalsoinvestigated.
*Correspondingauthor.Tel.:86-27-87543532;fax:86-27-87543632.E-mailaddress:hbxu@mail.hust.edu.cn(H.Xu).ListofAbbreviations:ALTϭalanineaminotransferase;ASTϭas-partateaminotransferase;t-BHPϭtert;butylhydroperoxide;GPCϭgelpermeatechromatography;GSHϭreducedglutathione;GSH-Pxϭglu-tathioneperoxidase;LDHϭlactatedehydrogenase.MAPϭMisgurnusanguillicaudatuspolysaccharide;MDAϭmalondialdehyde;OPTϭo-phthaldialdehyde;SODϭsuperoxidedimutase.
JournalofNutritionalBiochemistry13(2002)592–5970955-2863/02/$–seefrontmatter©2002ElsevierScienceInc.Allrightsreserved.PII:S0955-2863(02)00193-62.Materialsandmethods2.1.ChemicalsThiobarbituricacid(TBA),tert-butylhydroperoxide(t-BHP),glutathione(GSH),o-phthalaldehyde(OPT),Seph-adexG-100and5,5Ј-dithiohydroxyl-2,2Ј-dinitrobenzoxicacid(DTNB)werepurchasedfromSigmaCo.(StLouis,MO,USA).1,1,3,3-tetraethoxylpropane(TEP)andpyrogal-licacid(PA)weresuppliedbyFlukaChemicalCo.Pullulanstandards(P-112000,P-47300,P-22800,P-11800,P-5900,P-2700)wereboughtfromJapan.Kitsforaianineamino-transferase(ALT),aspartateaminotransferase(AST)andlactatedehydrogenase(LDH)wereobtainedfromInstituteofJianchengBioengineering(Nanjing,P.R.China).Me-diumforcellcultureandotherreagentsordisheswereorderedfromtheChinesesuppliers.2.2.PreparationofMAP2.5kgofliveloaches(Misgurnusanguillicaudatus,weight8Ϯ1.5g,length8.5Ϯ2cm,obtainedfromthemarketinWuhan.)werefirstimmersedin2.5Lofcleantap-waterandaeratedfor24hratroomtemperature.Then,afterbeingsupersonicatedfor1hronanultrasonicshaker(modelSB2200,Shanghai,China),theloacheswerere-movedbyfiltration.Thesupersonicationandfiltrationarenotfatal.Theextractwascentrifugatedat0°Cand8,000rpmfor10mininacentrifugalmachine(modelRS-2III,TomySeikoCo.,Tokyo,Japan),andsubsequentlyconcen-tratedto1/3volumeinvacuum.Theresiduewasextractedwith50ml/timeSevagreagent,CHCl3-nBuOH(V/Vϭ4:1)3timestodeproteinize.AfterremovingtheSevagreagent,4timesthevolumeofabsolutealcoholwasaddedtothewaterphaseandkeptat4°Covernightinarefrigeratortoprecipitatecarbohydratecompounds.AfterfilteringwithaBuchnerfunnelinvacuumandwashingwithabsolutealco-hol,thesedimentwasfrozenat-79.5°Covernightinasuperlow-temperaturefreezer(NUAIRE,Japan),andlyophilizedtoobtain7.5gofwhitepowderpreparation.Qualitativetestsshowthatthissedimentpreparationcontainingfreereductivepolysaccharides.Ithadcolor-reactionwithphe-nolsinsulfuricacidorwith3,5-dinitrosalicylicacid,butnocolor-reactionwithninhydrinorbiuretreagent.Aportionofthedriedsedimentpreparation(2g)washomogenizedwith100mlofhotdistilledwater,andafteraddingtoit50mlofanhydrousethanol,putintoarefrig-eratorandkeptat4°Covernight.TheMAPsedimentwasseparatedbycentrifugationat10,000rpm,washedwithanhydrousethanolfor3timesfrozenandlyophilizedtoyieldfineMAP(300mg).TheMAPwasfurtherpurifiedonaSephadexG-100gelcolumn(1ϫ50cm),usingHAc-NaAcbuffersolution(pH5)aseluentatthemobilerateof0.1ml/min.Thefractionsweredetectedbythephenol-sulfuricacidmethod.TheelutingcurvegaveasinglepeakandsuggestedthatMAPwaspurified.Thecontentoftotalsugarwas95.7%.