1pp B6 11 - Vitamin B6 Vitamin B6 Spring 2011 2011 Pages...

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itamin B6 Vitamin B6 pring 2011 Spring 2011 Pages 264-269
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Vitamin B6: History • First identified rats: 1930’s –antidermatitis, antianemia factor • Deficiency & convulsive seizures infants 1950’s Heat Treated
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xperimental Human Infant B6 Deficiency Experimental Human Infant B6 Deficiency • Experimental B6 deficiency in infants – deprived of B6 in formula for purpose of ocumenting clinical symptoms and documenting clinical symptoms and response to therapy • Determine if B6 was essential to humans • Unethical human experimentation • Parents of infants not fully informed.
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Experimental B6 Deficiency Infants Deprived of B6 B6 -stunted growth -anemia -seizures Symptoms reversed with B6 admin
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itamin B6: Chemistry tructurally- lated compounds Vitamin B6: Chemistry Structurally related compounds •Pyridoxine: alcohol (PN) •Pyridoxal: aldehyde (PL) • yridoxamine am ine(PM) Pyridoxamine: amine (PM) •5’-phosphate derivatives of
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Fig. 9-35, p. 364
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itamin B6 Stability Vitamin B6 Stability • Light sensitive eat sensitive • Heat sensitive –Particularly pyridoxal-P
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itamin B6 Stability Vitamin B6 Stability – pyridoxine-HCl more stable •used in foods that are heat-processed –pasteurized infant formulas –major form in supplements nd fortified foods a d o t ed oods
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itamin B6 Food Sources Vitamin B6 Food Sources Best - Meat (0.3 mg / 3 oz) • Muscle-derived meat: beef, pork, chicken, turkey, fish rgan meats Organ meats • Fruits & vegetables (~0.8 mg/serving) ower bioavailability - Lower bioavailability • nuts • beans • banana • Fortified food products ady at ereal • ready-to-eat cereal • may have 100% RDA per serving
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Vitamin B6: Absorption • Small intestine • Passive diffusion • Alkaline phosphatase dephosphorylates PLP – free vitamin enters enterocyte • Rephosphorylated by pyridoxal kinase and ATP rapped inside cell • Trapped inside cell • Bioavailability – Mixed diet: 75% – Supplement: >90%
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itamin B6: Transport Vitamin B6: Transport • Transport: albumin (plasma) –Main circulating form - PLP
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Vitamin B6: Metabolism – Pyridoxal phosphate (PLP) oenzyme form •Coenzyme form •Pyridoxine oxidase required to nvert other forms to PLP convert other forms to PLP –FAD dependent enzyme –liver
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Fig. 9-36, p. 364
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itamin B6: Storage Vitamin B6: Storage • Body store: 60-170 mg 0 0% in muscle – 80-90% in muscle – Bound to glycogen phosphorylase – Overall body half-life: ~25 days
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Vitamin B6: Excretion • Urinary excretion –4-pyridoxic acid • rimary excretory product primary excretory product •metabolically inactive •reflects recent dietary intake –may not reflect long-term status
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itamin B6: Functions 100 reactions: coenzyme PLP Vitamin B6: Functions >100 reactions: coenzyme PLP mino acid metabolism – Amino acid metabolism • transamination •deam inat ion • Decarboxylation – One-carbon Metabolism Heme nthesis
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This note was uploaded on 12/09/2011 for the course HUN 4445 taught by Professor Sitren during the Spring '08 term at University of Florida.

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1pp B6 11 - Vitamin B6 Vitamin B6 Spring 2011 2011 Pages...

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