Flavonoid Composition of Citrus Juices_review

Molecules2007,12,1641-1673moleculesISSN1420-3049*,DavideBarreca,ClaudiaGargiulli,UgoLeuzziandCorradoCaristi*DipartimentodiChimicaOrganicaeBiologica,UniversitàdiMessina,SalitaSperone31,I-98166Messina,Italy;E-mails:[e-mail];[e-mail];[e-mail]*Authorstowhomcorrespondenceshouldbeaddressed;E-mails:[e-mail];[e-mail]:22June2007;inrevisedform:30July2007/Accepted:31July2007/Published:3August2007Abstract:IntheearlyninetiesthepresenceofflavonoidsinCitrusjuicesbegantoattracttheattentionofanumberofresearchers,asaresultoftheirbiologicalandphysiologicalimportance.Thisshortreviewwillexploretwodifferentaspects.ThefirstpartwillfocusonanalyticaltechniquesforthecharacterizationofjuicesfromdifferentCitrusfruitsregardingtheirflavonoidcontent(evenifpresentinonlytraceamounts),concentratingonthemostwidelyusedmethods(LC-MSandLC-MS-MS).ThesecondpartanalyzesdatareportedintheliteratureregardingthecompositionofCitrusjuices.Themaincomponentsthathavebeendetectedsofarareflavanone-O-glycosidesandflavone-O-or-C-glycosides.Thepresenceofsuchderivativesinvarioushand-squeezedandindustrialjuicesisdiscussed,withspecialemphasisontheircorrelationtodifferentspecies.Keywords:Citrus,flavonoids,Citrusjuices,HPLC,HPLC-MSIntroductionPlantflavonoids[1]arealargegroupofverydifferentcompoundssharingthecommonfeatureofphenolmoieties.Theyare,withafewnotableexceptions,plantmetabolitesderivingfromtheshikimatepathwayandthephenylpropanoidmetabolism[2].Flavonoidsarearomaticsecondaryplantmetabolites,whichhavebeenrecognizedasimportantduetotheirphysiological[3]andMolecules2007,121642pharmacological[4]roleandtheirhealthbenefits[5].Theamountofinteresttheyhaveattractedisdemonstratedbymorethan13,000articlesandbooksdealingwithvariousaspectsofflavonoidchemistry,biochemistry,pharmaceuticalandnutritionalrolewhichhaveappearedsince1990.Flavonoidsshowastrongantioxidantandradicalscavengingactivity[6]andappeartobeassociatedwithreducedriskforcertainchronicdiseases[7],thepreventionofsomecardiovasculardisorders[8]andcertainkindsofcancerousprocesses[9].Flavonoidsexhibitalsoantiviral[10],antimicrobial[11],andanti-inflammatoryactivities[12],beneficialeffectsoncapillaryfragility[13]andanabilitytoinhibithumanplateletaggregation[14],antiulcer[15]andantiallergenic[16]properties.However,theactualinvivomechanismofactionislargelyunknown.Oneofthereasonsisthatmoststudieshavefocusedoninvitrotestsatdosesorconcentrationsmuchhigherthanthosedocumentedinhumans,whereasfewclinicalinvestigationshavebeencarriedoutonbiomarkersofsomeofthediseasesmentionedabove,butresultshavebeencontradictory[17].Epidemiologicalstudieshaveshownaninverseassociationbetweenriskandintakelevelofsomeparticularflavonoids,butfurtherclinicaltrialsareneededtoassessamoreprecisecorrelationbetweenthelevelofflavonoidsconsumptionandhumanhealthbenefits[18].However,theprobablemechanismbywhichtheyact,andthepotentialclinicalapplicationshavebeenreviewed[19].Flavonoidsarefrequentlyfoundinfruits[20],vegetablesandcereals[21].Overthepastfewyearsinvestigationsintoflavonoidsfromdietarysourceshaveattractedanevergrowinginterestasaconsequenceoftheirwell-establishedversatilehealthbenefits[22].Foodpreparationandprocessingoffreshfruitsandvegetablesmaydecreaseflavonoidscontentby50%owingtotheirleachingintowater,orbyremovaloftherichestpartsoftheplant[23].Inordertoovercomethisproblem,andevenmoretomakeprocessedfoodstuffsabettervehicleforflavonoidintake,aconsiderableamountofworkhasbeendoneonthemodificationoftheirbiosynthesisinplants.Recentadvancesinbioengineeringhavebeenextensivelyreviewed[24].Forthetimebeing,themainsourceofflavonoidintakeremainsdietaryintake.Thisaccountsforanaveragedailyintakeofflavonoidsbetween70and170mg/day,thedifferencemostlydependingondietaryandculturalhabits.CitrusfruitsandCitrusjuicesstandoutamongthemostcommonphenolic-richdietarysources[25].ThemostsignificantcroppedCitrusfruitsareoranges,mandarins,grapefruitsandacidCitrusfruits,namelylemons,bergamotsandlimes.Freshfruitsandtheirhand-squeezedorindustriallyprocessedjuices,containmostlyflavanonesandflavones.Althoughmorethan5000flavonoidderivativeshavebeencharacterized[26],onlyalimitednumberofrepresentativederivativeshavebeenfoundandidentified.Manyothersareoftenonlypresentinverylowconcentrationsandhaveyettobeidentified.Theirsignificance,however,mayoutweightheirsimpleconcentrationlevels.Ingeneral,flavonoidsmaycontributetofruitandjuicequalityinmanyways,influencingtheappearance,thetasteandthenutritionalvalueoftheproductfromtheplant.Inlemonandorangejuices,forinstance,hesperidincancontributetotheformationofsedimentswhichresultinundesirablecloudiness[27],whereasnaringinmarkedlyinfluencesthebitternessofthejuiceofgrapefruitsandbergamots[28].ThisshortreviewexaminesthedataintheliteratureregardingtheflavonoidcontentofCitrusjuices,particularlyoverthelastfifteenyears,andfocusesonthejuicesofthemostwidespreadCitrusspecies.Molecules2007,121643Citrusjuiceflav