Scurvy in the British Royal Navy James Lindpublished hisTreatise on theScurvy in 1754.Lime juice wasmade mandatory onBritish Navy sailingships 40 years later
The term “vitamin C” encompasses L-[+]-ascorbic acid and its derivatives with identicallevels of biological effects. Chemically, ascorbicacid is the enolic form of 3-oxo-L-gulofuranolactone (A).
Plants and many animals can synthesize it fromglucuronic acid. Since humans, apes, and guineapigs lack the last enzyme in the enzyme pathway,L-gulonolactone oxidase, the vitamin is essentialfor them.
Chemical formulasSummary formula:Geometrical formulas:C6H8O6The effective form for treatment of colds and flu is the ascorbate form.The bioactive form of vitamin C is only the L-form(synthetic ascorbic acid: 50 % L-form + 50 % D-form;natural sources of vitamin C contain only the L- form).
1. Vitamin C acts as a reducing agent:2. The oxidation of p-hydroxphenyl pyruvate tohomogentisate in the metabolism of tyrosineneeds the presence of vitamin V and Cu+23. Role in iron absorption: Ascorbic acid presentin food reduces the inorganic Fe+++(ic) to Fe++(ous) form.
4. Vitamin-C acts as a coenzyme forhydroxylases. Hydroxylation reactions areinvolved in the synthesis of collagen andother compounds:
5. Formation of carnitine in liver by hydroxylationof γ-butyrobetaine involves vitamin-C, α-ketoglutarate, Fe++and a dioxygenase.6. Vitamin-C required for the normal function ofadrenal cortex.
7. The formation of FH4 from folate needsvitamin-C. Tetrahydrofolate [FH4] is acoenzyme from of folate.8. Ascorbic acid is necessary for the formationof tissue ferritin.
9. Vitamin C is needed for the functional activityof fibroblast, osteoblast, and consequently forthe synthesis of MPS of connective tissues,osteoid tissues, dentine tissues and intracellularsubstance involved in the cementing ofcapillaries.
Collagen formation Iron and hemoglobin metabolism Tryptophan metabolism Tyrosine metabolism
24 Absorption of ascorbic acid into the bloodstream takes place in the upper part of thesmall intestine Excretion –through urine
VITAMIN C NEEDS • 10 MG/DAY TO PREVENT SCURVY • RDA IS 60 MG/DAY • ONE ORANGE = 70 MG • ONE CUP O.J. = 124 MG • AVERAGE SUPPLEMENT IS 500 MG • 250 AS AN ANTIOXIDANT • 2000 MG IS MEGADOSE
27 Men – women – 70-90mg Children –.40mg Infant – 25mg Pregnancy & lactation – 80mg
VITAMIN C most famous vitamin (also called ascorbic acid) helps form collagen or body cement helps in growth and repair of body tissue andblood vessels28
prevents scurvy can be decreased by cigarette smoking, stressfulinjuries and oral contraceptives excessive doses can cause kidney stones andbreak down red blood cells
30 synthesis of collagen Maintenance – necessary for maintenance ofbones & proper functioning of the adrenal &thyroid gland .
antioxidant It stimulates immune function, combats bacterialinfection, reduces effects of allergy-producingsubstances and protects vitamins, A, E and someB complex vitamins from oxidation.
32SCURVY Fragility of blood vessels Easy bruising, hemorrhage Poor healing Pain in Bones & Muscle Poor Bone & Dentin formation Compromised immunity
The well-known deficiency is Scurvy Weakness Fatigue Inflammation of the gum Impaired wound healing Hemorrhages depression
SCURVY- defect lies in the failure of intercellular cementsubstance Fragile capillaries-petechial, sub-cutaneous ,sub-periostialor internal hemorrhages. Poor /Delayed wound healing. Poor dentine formation Gum bleed- gums are swollen, spongy bleeds onpressure Poor mineralization of bones Anemia- microcytic - hypochromic
Toxicity With too high a dose, diarrhea, dizziness,gastritis, headaches, light-headedness, nausea,and vomiting can occur, though these may be justtemporary. Rare symptoms include abdominalpain and anemia. Daily dosages above 500 mg/day may depletethe level of copper in the blood of males.
Toxicity Women taking 2000 mg or more a day may experiencefertility problems; individuals taking 2000 mg or more a daymay lower the resistance of their white blood cells to fightone common form of bacteria, Those taking 3000 mg or more a day may experiencereduced levels of the amino acid cysteine in the blood. Dosages above 4000 mg/day can increase kidney stoneformation . Chewable vitamin C can lead tosevere dental erosion
40 .SYNTHESIS OF COLLAGEN • BLOOD VESSELS • SCAR TISSUE, BONE MATRIX • ANTIOXIDANT • HELPS ABSORB IRONVitamin C -
stimulates immune function, combatsbacterial infection, reduces effects of allergy-producing substances and protects vitamins,A, E and some B complex vitamins fromoxidation.
42 • SCURVY - SAILORS AFTER A FEWWEEKS WITHOUT FRESH FRUITSAND VEGETABLES. WAS THOUGHTTO BE AN INFECTIOUS DISEASE •“LIMEYS”
Vitamin C DeficiencyVitamin C DeficiencyCorkscrew Hair
Vitamin C DeficiencyVitamin C DeficiencyPerifollicular Petechiae
Vitamin C DeficiencyVitamin C DeficiencyScurvy
Vitamin C (Ascorbic acid)Vitamin C (Ascorbic acid)Gum changes in infantscurvy:The swelling andhemorrhages are confinedto the areas of the gumsurrounding the eruptingteeth.
Vitamin C (Ascorbic acid)Vitamin C (Ascorbic acid)Gums in scurvy:The gums are blue-red andglossy swollen in this patientwith severe scurvy. Theearliest changes are swellingof the internal dental papillaeand tendency to bleed easily.Lesions occur only in relationto teeth and so in young infantsand edentulous adults they areabsent. In advanced casesthere is usually an element ofinfection and antibiotics as wellas vitamin C are required forhealing
Vitamin C (Ascorbic acid)Vitamin C (Ascorbic acid)Very advanced gum lesions in scurvy
Vitamin C (Ascorbic acid)Vitamin C (Ascorbic acid)Orbital hemorrhage:This is a dramatic butinfrequent sign ofscurvy. There iscomplete clearing withtreatment.
Vitamin C (Ascorbic acid)Vitamin C (Ascorbic acid)Splinter hemorrhage:In this unusual sign inscurvy the hemorrhages arearranged in a semicircularlattice involving nail beds.They are more extensivethan those in sub-acutebacterial endocarditis.
METABOLIC FUNCTION OF VITAMINC 11)) Electron transportElectron transporto Loses electrons easily because ofLoses electrons easily because ofreversible monovalent oxidation toreversible monovalent oxidation toascorbyl radicalascorbyl radicalo Involved in many electron transportInvolved in many electron transportreactionsreactionso Ascorbic acid regenerated – ascorbyl ionAscorbic acid regenerated – ascorbyl ionreduced by two enzymesreduced by two enzymes dehydroascorbate reductase ascorbate cytochrome-b5.
2) Antioxidant functions Antioxidant Activity Reacts and removes active oxygen species Pro-oxidant Activity Reduces metals to their pro-oxidant forms
3)Collagen synthesiso Helps in hydroxylation of prolineHelps in hydroxylation of prolineand lysine in procollagenand lysine in procollagenmoleculemoleculeo Catalyzed by prolyl hydroxylaseCatalyzed by prolyl hydroxylaseand lysyl hydroxylaseand lysyl hydroxylaseo Hydroxylation of procollagenHydroxylation of procollagennecessary for folding into triplenecessary for folding into triplehelical structurehelical structure
4)4) Catecholamine biosynthesisCatecholamine biosynthesiso Serves asServes as electron donorelectron donor forfor dopamine ß –dopamine ß –monooxygenasemonooxygenase5)5) Carnitine synthesisCarnitine synthesiso Ascorbic acid has a cofactor of two FeAscorbic acid has a cofactor of two Fe2+2+containing hydroxylases involved in synthesiscontaining hydroxylases involved in synthesisof carnitineof carnitine