vitamins K final.pdf for nursing student

pharmacology
powerpoint presentation of vitamin k

3. VITAMIN K

4. BY
Dr. Samy Ali Hussein Aziza
Professor of Biochemistry and
Clinical Biochemistry
Faculty of Veterinary Medicine,
Moshtohor, Benha University,
Egypt.
E-Mail: [email protected]

5. VITAMIN K
Synonyms:
ANTI-HEMORRHAGIC FACTOR
or
NAPHTHOQUINONES
Or
PHYLLOQUINONE orMENAQUINONES

6. Vitamin K
Chemistry:
ThevarioussubstancesshowingVit.K
activityarecalled(naphthoquinone)
Vitamin K is found naturallyas:
K1(phylloquinone,orphytylmenaquinone)in
greenvegetables.
K2(multiprenylmenaquinone)producedby
intestinalbacteria.
K3 (menadione)is syntheticform.
For therapy,a synthetic derivative of vitamin K,
menadione, is available.

7. Thebodyisabletoconvertsynthetically
preparedmenaquinone(menadione)anda
numberofwatersolubleanalogstoa
biologicallyactiveformofvitaminK.
AlltypesofVit.Kcontainmethylgroupat
carbonnumber2.
Activityisduetothismethylgroup.
Substitutionofmethylgroupbyotheralkyl
radicalsorbyhydrogenresultsinreduction
inactivity.

8. Vitamin K1

9. Vitamin K2
"n"canbe6,7or9
isoprenoidgroups

10. Vitamin K3
(menadione)

11. Function of Vitamin K
ProductionofcoenzymeQ,its
functionaselectroncarrier,
helpingtheoxidationinthe
respiratorychainandproduction
ofATP.
VitKisrequiredinthehepatic
Synthesisofprothrombinand
bloodClottingfactorsII,Vll,
lX,&X.

12. 1-Formationofγ-carboxyglutamate(Gla):
Vit.K1hasbeenshowntoberequired
fortheconvertionofseveralclotting
factorsandprothrombintotheactive
state.
Prothrombinissynthesizedinan
inactiveprecursorformcalled
preprothrombin.
Preprothrombin(precursor)inactive
Vit.Kgiveprothrombin(active).

13. Convertiontotheactiveformrequiresavit.K
dependantcarboxylationofspecificglutamic
acidresiduestoɤ-carboxyglutamicacid
residues.
Theɤ-carboxyglutamicacidresiduesaregood
chelatorsandallowprothrombintobind
calcium.
Theprothrombin-calciumcomplexinturn
bindstothephospholipidsmembrane,where
proteolyticconversiontothrombincanoccur
invivo.

14. 2-Interactionofprothrombinwithplatelets:
ThetwoCOO-residuesofprothrombin
chelate+velychargedCa2+.The
prothrombin-Ca2+complexisableto
bindthePLmembrane(phospholipids)
essentialforbloodclottingonthesurface
ofplatelets.Attachmenttotheplatelet
increasestherateatwhichtheproteolytic
conversionofprothrombintothrombin
canoccur.

17. Themechanismofthecarboxylationreaction
hasnotbeenfullyclarified,butappearsto
involvetheintermediateformationofa2,3-
epoxidederivativeofvitaminK.
Duringthecarboxylationreactionreduced
hydroquinoneformofvitaminKisconverted
toa2,3-epoxideform.Theregenerationofthe
hydroquinoneform requiresan
uncharacterizedreductase.Thislatterreaction
isthesiteofactionofthedicumarolbased
anticoagulantssuchaswarfarin.

18. •Dicumarol,anaturallyoccuring
anticoagulant,mayinhibitthereductase
whichconvertstheepoxidebacktothe
activevitamin.
Briefly,theformationofGlaissensitive
toinhibitionbydicumarolanatural
anticoagulantpresentinspoiledsweet
clover&warfarin,asyntheticanalogof
vitaminK.

19. Role of vitamin K in blood coagulation

20. 3-Roleofγ-carboxyglutamateresiduesinother
proteins:
Glaisalsopresentinotherproteins(for
example,osteocalcinofbone)unrelatedto
theclottingprocess.
However,thephysiologicroleofthese
proteinsandthefunctionofvitaminKin
theirsynthesisisnotyetunderstood.

21. Vitamin K Is Also Important in Synthesis of
Bone Calcium-Binding Proteins
•Treatmentofpregnantwomenwithwarfarincan
leadtofetalboneabnormalities(fetalwarfarin
syndrome).Twoproteinsthatcontainɤ-
carboxyglutamatearepresentinbone,
osteocalcin,andbonematrixGlaprotein.
Osteocalcinalsocontainshydroxyproline,soits
synthesisisdependentonbothvitaminsKand
C;inaddition,itssynthesisisinducedbyvitamin
D.Thereleaseintothecirculationofosteocalcin
providesanindexofvitaminDstatus.

22. Distribution and requirement of vitamin K
VitaminKisfoundincabbage,
cauliflower,spinach,eggyolk,and
liver.
Thereisalsoextensivesynthesisof
thevitaminbythebacteriainthegut.
ThereisnoRDAforvitaminK,but
70to140μgperdayisrecommended
asanadequatelevel.

23. RECOMMENDED DAILY
ALLOWANCE OF VITAMIN K
•Males 65 –80 micrograms
•Females 55 –65 micrograms
•Pregnancy 65 micrograms
•Lactation 65 micrograms

24. Deficiency of vitamin K
1-Deficiency of vitamin K:
Itisunusualbecausevitkisproducedby
theintestinalfloraorfromdiet.
Ithappensinpeoplewhoaretaking
antibioticsandcanleadto
hypoprothrombinemia.
2
nd
generationofCephalosporinshavea
warfarin-likemechanism.(theyshouldbe
takenwithvitK).

25. 2-Defficiency of vitamin K in newborn:
Newbornshavesterileintestinesand
cannotinitiallysynthesizevitK.
Becausehumanmilkprovidesonly
1/5ofthedailyrequirementforvitk,
itisrecommendedthatallnewborns
receiveasingleI.M.doseofvitKas
prophylaxisagainesthemorrhagic
disease.

26. Defficiency of vitamin K in man
The only known symptom of vitamin K def.
in man is increased coagulation time.
The most common def. is seen in:
Newborn infants.
In patients with obstructine jaundice.
Otherdiseasesleadingtoseverfat
malabsorption.
Patientsonlong–termantibiotictherapy,
whichmaydestroyvit.K–synthesizing
organismintheintestine.

27. •Finally,Vit.Kdef.isoccusionally
seenintheelderly,whoareprone
topoorliverfunction(reducing
preprothrombinsynthesis)andfat
malabsorption.
•VitaminKdef.shouldbe
suspectedinanypatient
demonstratingeasybruisingand
prolongedclottingtime.

28. Clinical findings 0f Vit. K deficiency
•Easy bruising.
•Echymotic patches.
•Mucous membrane hemorrhage
•Internal bleeding.
•Prolonged prothrombin time.

29. Echymotic
patches

30. Toxicity of vitamin K
•Prolongedadministrationof
largedosesofvitaminKcan
producehemolyticanemiaand
jaundiceintheinfant,dueto
toxiceffectsonthemembrane
ofredbloodcells.

31. Vitamin K
Phylloquinone: menaquinones
Functions:
Coenzymeinformationofɤ-
carboxyglutamateinenzymesof
bloodclottingandbonematrix.
Deficiency disease :
Impairedbloodclotting,hemorrhagic
disease.

32. References:
1.Lippincott’s review of biochemistry, 3
rd
edition.
1.Biochemistry Stryer 5
th
edition.
2.Harper,s illustrated Biochemistry 28
edition.

33. Fat soluble vitamins
Learning outcomes:
Classify vitamins.
List the dietary sources of Vitamin A
Discuss the role of Vitamin A in vision.
Discuss the deficiency manifestations of Vitamin
A.
Discuss the role of Vitamin D in the body.
Discuss the deficiency manifestations of Vitamin
D in both adults and children
Discuss why vitamin D is considered as an
hormone.
Explain the role of vitamin K in coagulation.
Discuss the role of Vitamin E .