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Vitamin E: Essential Antioxidant for Cellular Integrity

Explore the lipophilic nature and functions of Vitamin E, its chemical structure, absorption, storage, and role in preventing oxidative damage. Discover the benefits, sources, deficiency symptoms, and recommended dosages of Vitamin E for optimal health.

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Vitamin E: Essential Antioxidant for Cellular Integrity

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  1. VitaminEislipophilicincharacterandisfoundinassociationwithlipoproteins,fatdepositsandcellularmembranesVitaminEislipophilicincharacterandisfoundinassociationwithlipoproteins,fatdepositsandcellularmembranes

  2. Chemicalnature: • VitaminEischemicallyknownastocopherol(Greek:tocos=childbirth,piro=tobearandol=alcohol) • Analcoholwascapabletoprevent • reproductivefailureinanimals • Henceitisknownasanti-sterilityvitamin • Chemistry: • VitaminEisthenamegiventogroupoftocopherolsandtocotrienols

  3. About8tocopherolshavebeenidentified • Alpha-tocopherolismostactive • Thetocopherolsarederivativesof6-hydroxychromane(tocol)ringwithisoprenoidsidechain • Theantioxidantpropertyisduetothechromanering • Therearefourmainformsoftocopherols • Theyare

  4. α -tocopherol:5,7,8trimethyltocol • β -tocopherol:5,8dimethyltocol • γ -tocopherol:7,8dimethyltocol • δ -tocopherol:8methyltocopherol • α –tocopherolismostactiveandpredominantformofvitaminE • Tocotrienols:TherearefourrelatedvitaminE • compoundscalled α,β,γ and δ tocotrienols

  5. CH3 CH3CH3 CH • 3 • CH2-(CH2-CH2-CH-CH2)3-H • OH • CH3 • α-Tocopherol(5,7,8-trimethyltocol)

  6. CH3 CH3CH3 CH2-(CH2-CH2-CH-CH2)3-H OH CH3 β-Tocopherol(5,8-dimethyltocol CH3  CH3CH3 CH2-(CH2-CH2-CH-CH2)3-H CH 3 OH γ-Tocopherol(7,8-dimethyltocol)

  7. ABSORPTION • VitaminEisabsorbedalongwithfatinthe • uppersmallintestine • Mechanism:VitaminEcombineswithBilesalts(micelles)toformmixedmicelleandtakenupbythemucosalcell • Inthemucosalcell,itisincorporatedinto • chylomicrons

  8. DietaryvitaminEisincorporatedtochylomicrons • Inthecirculation,chylomicronstransportvitaminEtotheperipheraltissueortotheliver • HepaticvitaminEisincorporatedtoVLDL • Inthecirculation,VLDLisconvertedLDL • VitaminEistransportedwithLDLtoreachtheperipheraltissuesincludingadiposetissue

  9. Storage: • Mainlystoredinliverandadiposetissue • Presentinbiologicalmembranes,becauseofitsaffinitytophospholipids

  10. MostofthefunctionsofthevitaminEare • relatedtoitsantioxidantproperty • Itpreventsthenon-enzymaticoxidationsofvariouscellcomponentsbymolecularoxygenandfreeradicalssuchassuperoxideandhydrogenperoxide(H2O2) • Seleniumhelpsinthesefunctions • ItprotectsthePUFAfromperoxidationreactions

  11. VitaminEisessentialformembranestructureandintegrityofthecell,henceitismembraneantioxidant.VitaminEisessentialformembranestructureandintegrityofthecell,henceitismembraneantioxidant. Itpreventstheper oxidationofPUFA ItprotectstheRBCfromhemolysisby oxidizingagents(H2O2) Itisassociatedwithreproductivefunctionandpreventssterility

  12. VitaminEpreservesandmaintainsgerminalepitheliumofgonadsforproperreproductivefunctionVitaminEpreservesandmaintainsgerminalepitheliumofgonadsforproperreproductivefunction Itincreasesthesynthesisofhemebyenhancingtheactivityofenzyme– δ aminolevulinicacid(ALA)synthaseandALAdehydratase Itisrequiredforcellularrespiration–through ETC(StabilizecoenzymeQ) VitaminEpreventstheoxidationofVitaminAandcarotenes

  13. Itisrequiredforproperstorageofcreatineinskeletalmuscle Itisrequiredforabsorptionofaminoacids fromintestine Itisinvolvedinsynthesisofnucleicacids Itprotectstheliverfromtoxiccompounds suchascarbon tetra chloride. 13.ItworksinassociationwithvitaminA,Cand beta-carotene,todelaytheonsetofcataract

  14. 14.VitaminEisrecommendedforthe • preventionofchronicdiseasessuchascancer • andheartdisease • VitaminEpreventsoxidationofLDL • OxidizedLDLpromotesheartdiseases • Selinium:Itisacomponentofglutathioneperoxidaseandfunctionasantioxidant • ItreducestherequirementofvitaminEindiet • ItisrequiredfornormalpancreaticfunctionandenhancingtheabsorptionofvitaminE

  15. -10mg/day • 8mg/day • 10mg/day • 12mg/day • Males • Females • Pregnancy • Lactation • 15mgofvitaminEisequivalentto33IU • Pharmacologicaldoseis200-400IU/day • Sources: • Richsourcesarevegetableoils • Includesgermoil,sunfloweroil,cornoilandmargarine

  16. Inhumans,deficiencyofvitaminEisseenin • Prematureinfants: • TransferofvitaminEfrommaternalbloodoccursduringlastfewweeksofpregnancy • PrematureinfantswillhavevitaminEdeficiency • Impairedabsorption:Seeninconditionssuchas • abetalipoproteinemia(fatmalabsorption) • Obstructivejaundice • Intestinaldiseasessuchasceliacspure DEFICIENCY

  17. GeneticvitaminEdeficiency:ItiscausedbylackofaproteinthatnormallytransportsGeneticvitaminEdeficiency:Itiscausedbylackofaproteinthatnormallytransports • α-tocopherolfromhepatocytestoVLDL • Clinicalfeatures: • Hemolyticanemiaormacrocyticanemiaseen • inprematureinfants • Inadults,increasedsusceptibilityofRBCs to hemolysisunderoxidativestress. • Muscleweaknessandproteinuriaisseen

  18. Musculardystrophy • VitaminEdeficiencyleadstoincreasedoxidationofPUFA,withconsumptionofoxygenandproductionofperoxides • Peroxidesincreasetheintracellularhydrolase • activity, which catalyzebreakdownsinmuscleandproducemusculardystrophy • Themusclecreatineislowandcreatinuriaoccurs

  19. Hepaticnecrosis • VitaminEandseleniumpreventshepaticnecrosis • Cerebellarataxiaandimpairedvision: • Chronicdeficiencyinchildrenisassociatedwithataxia,weakness,lossoftouchandpositionsenses,impairedvisionandretinopathy • Increasedlipidperoxidationinnervoustissuecausesneurologicallesions

  20. OxidationofPUFAinrodsleadstooxidativedamageinretina • Deficiencyinanimals: • Musculardystrophyandreproductivefailure • VitaminEisleasttoxic

  21. TherapeuticusesofvitaminE

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