Vitamins Flashcards
Vitamin B1
Thiamine (thiamine pyrophosphate=carries aldehyde)
Decarboxylation reaction: 4 reactiosn
1) alpha ketoglutarate dehydrogenase (TCA)= A
2) transketolase (HMP shunt) =T
3) pyruvate dehydrogenase (glycolysis to TCA) =P
4) branched AA dehydrogenase
makes ATP
Deficiency: impaired glycolysis, ATP depletion worsened by glucose infusion; highly aerobic tissue (B/H) affected first
Wernicke=confusion, nystagmus, ataxia, confabulation, memory loss (permanent)
Dry beri=polyneuritis, symmetrical muscle wasting
Wet beri=high output cardiac failure, edema
Vitamin B2
Riboflavin
Cofactor in oxidation and reduction FADH2 (FMN, FAD)
Deficiency = cheilosis (inflam of lips, scaling, and fissures at the corner of the mouth), corneal vascularization
The 2C’s of B2
Vitamin B3
Niacin, NAD+, NADP+
Derived from tryptophan (synthesis requires B6)
Glossitis
Severe defiency= Pellagra = diarrhea, dementia, dermatitis
1 ) Hartnupt dz=reduced tryptophan absorption
2) Malignant carcinoid syndrome = high tryptophan metab
3) INH = indirectly by lowering vitamin B6
Excess: flushing (pharmacologic dose for treating HL)
Vitamin B5
Pantothenate
Essential for CoA (cofactor for acryl transfer) and FA synthesis
Deficiency: dermatitis, enteritis, alopecia, adrenal insufficiency
Vitamin B6
Converted to pyridoxal phosphate, a cofactor for
1) transamination (ALT/AST)
2) decarboxylation
3) glycogen phosphorylase
Synthesis of cystathionine, heme, niacin, histamine, and NT such as serotonine, epi, NE, and GABA
Deficiency: convulsion, hyperirritability, peripheral neuropathy
Deficiency inducible by INH and OCP
Sideroblastic anemia due to impaired heme synthesis and iron excess.
Vitamin B7
Biotin
Carboxylation (add a 1-carbon group)
1) pyruvate carboxylase (pyruvate to oxaloacetate)
2) acetyl CoA carboxylase (acetyl CoA to malonyl CoA)
3) propionyl CoA carboxylase (propionyl CoA to methylmalonyl CoA)
Deficiency: rare. Dermatitis, alopecia, enteritis,
Caused by Abx use or excessive ingestion of raw egg
Vitamin B9
Folic acid, in foliage, small reserve in liver
Converted to THF, a coenzyme for 1 carbon transfer/methylation rxn
Important synthesis of nitrogenous base in DNA/RNA
Deficiency: macrocytic, megaloblastic anemia
No neuro symptoms (vs. B12). Most common deficiency in US, alcoholism and pregnancy (NT defect).
Deficiency caused by phenytoin, sulfonamide, MTX
Vitamin B12
Cobalamin, animal product, stored in liver
Cofactor for homocysteine methyltransferase and methylmalonyl CoA mutase
Deficiency: macrocytic, megaloblastic anemia, hypersegmented PMN, neurologic (paresthesia, subacute combined degeneration), prolonged deficiency leads to irreversible neurologic symptoms
Deficiency often caused by malabsorption
S adenosyl methionine
ATP + methionine = SAM
SAM transfers methyl unit
Regeneration of methionine (and thus SAM) is dependent on vitamin B9 and B12
Required for conversion of NE to EP
Vitamin C
If excessive: nausea, vomiting, diarrhea, fatigue, sleep problems
Increase the risk of iron toxicity in predisposed individuals
transfusion, hereditary hemochromatosis
Vitamin D
Not enough in breast milk (supplement in dark skinned pts)
If excessive: hypercalcemia, hyperciciuria, loss of appetite, stupor
D2=ergocalciferol from plants
D3=cholecalciferol from milk, formed in skin
25-OH D3= storage form
1,25-(OH)2 D3=calcitriol (active)
Vitamin E
E for erythrocytes
Antioxidant, protects RBC from free radicals
Deficiency: increased fragility of RBC (hemolytic anemia), muscle weakness, posterior column, and spinocerebellar tract demyelination.
Zinc
Important for >100 enzymes, zinc finger (TF motif)
Deficiency: delayed wound healing, hypogonadism, decreased adult hair (axillary, facial, pubic) dysgeusia, anosmia
May predispose to alcoholic cirrhosis
Vitamin A
Antioxidant: retinal pigment, epith diff (pancreatic, muscus), prevents squamous metaplasia.
Used to treat measles, AML subtype M3
Found in liver and leafy veggie
Deficiency: nightblindness, dry skin
Excess: arthralgia, fatigue, headache, skin changes, sore throat, alopecia, teratogenic (cardiac, palate, cleft)
