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Before we begin…….

Before we begin……. Which of the B vitamins is the other name for Niacin? . B1 B3 B5 B7. Which of the B vitamins is the other name for Niacin? . B1 B3 B5 B7. Which amino acid can Niacin be synthesized from? . Proline Alanine Tryptophan Tyrosine.

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Before we begin…….

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  1. Before we begin…….

  2. Which of the B vitamins is the other name for Niacin? • B1 • B3 • B5 • B7

  3. Which of the B vitamins is the other name for Niacin? • B1 • B3 • B5 • B7

  4. Which amino acid can Niacin be synthesized from? • Proline • Alanine • Tryptophan • Tyrosine

  5. Which amino acid can Niacin be synthesized from? • Proline • Alanine • Tryptophan • Tyrosine

  6. Niacin deficiency can lead to: • Anemia • Seizures • Scurvy • Pellagra

  7. Niacin deficiency can lead to: • Anemia • Seizures • Scurvy • Pellagra

  8. Niacin Kirsten Boestfleisch, Lindsay Edmonds, Lena Husnay, Sarah Johnson

  9. Niacin • Vitamin B3 or nicotinic acid • Inositol hexaniacinate is also another form • Directly converted to nicotinamide • Niacin, nicotinic acid, and nicotinamide are cofactors for: • NAD+ • NADP+ *Both are involved in energy production • Water soluble (body does not store it) • Highest concentrations are found in the liver as NAD+ Niacin commons.wikimedia.org Nicotinamide

  10. Food Sources • Plant products • Wheat bran • Corn • Enriched breads and cereals • Legumes • Nuts • Meat products – NAD+ and NADP coenzymes • Released during cooking • Need fortification

  11. Why is Niacin Necessary? • Necessary for the metabolism of carbohydrates into glucose, which is used for energy • Helps the body use fat and protein • Boost immune system to fight disease • Healthy liver • Proper function of the nervous system • Improves circulation

  12. Synthesis from Tryptophan • Nicotinamide can be synthesized from tryptophan • Inefficient process: 1 mg of niacin needs 60 mg of tryptophan • Niacin deficiency oftentimes results when both niacin and tryptophan levels are insufficient

  13. Major Functions 1. Energy metabolism – NAD+ is reduced to NADH in several reactions: • Glycolytic reactions • Oxidative decarboxylation of pyruvate • Oxidation of acetate in the TCA cycle • Oxidation of alcohol • Beta oxidation of fatty acids • Many other cellular oxidation reactions Oxidation of NADH allows transfer of electrons in the electron transport chain to produce ATP.

  14. Major Functions Continued 2. NADP+ is reduced to NADPH • Pentose phosphate pathway • Malate-pyruvate shuttle (crosses mitochondrial membrane) NADPH becomes a reducing agent for many cellular macromolecules, manufacture of deoxyribonucleotides, cholesterol synthesis, and fatty acid production.

  15. Major Functions Continued 3. Poly(ADP-ribosyl)ation reactions • DNA metabolism and genomic stability 4. Mono(ADP-ribosyl)ation reactions • ADP-ribose attaches to amino acid side chains to make mono(ADP-ribose) • Aids cyclic ADP-ribose and NAADP formation • Allows control of intracellular calcium levels = cellular signaling

  16. Major Functions Continued *Cyclic ADP-ribose • Synthesis: ADP-ribose attaches to an internal ribose linkage • Important regulator of the CICR (calcium-induced calcium release) • Other regulators of calcium release: • Inositol-1,4,5-triphosphate (IP3) - a type of calcium channel • NAADP (a contaminate of NADP found to mobilize calcium)

  17. Major Functions continued 5. SIR2 (rats)/SIRT1 (humans) deacetylation reactions • Involved in genomic stability and expression particularly through: • Histones – involved in DNA transcription • Protein p53 – tumor suppressor A deficiency in niacin could result in a more active gene expression in DNA, making DNA more susceptible to structural damage.

  18. Specific Absorption • Some in stomach lining • Mostly in small intestine • At low concentrations: • Sodium-dependent facilitated diffusion • Carrier-mediated transport • Anion antiporters

  19. Transport Mechanism • Portal circulation • Facilitated diffusion into erythrocytes • Nicotinic acid or nicotinamide • Liver • Formation of NAD from tryptophan, nicotinamide, or nicotinic acid • Products for urinary excretion

  20. Mechanism of Action on Various Tissues

  21. 1 & 2: Niacin Action in the Adipose Tissue • Affects: adipocyte • Targets: HCAR2 receptor • Leads to: • Decreased lipolysis • Decreased VLDL and triglycerides

  22. 3 & 4: Niacin Action in the Artery • Affects: endothelium • Targets: • NAD+ phosphate • Lowers LDL oxidation – Decreases vascular inflammation • Redox sensitive genes • Lowers MCP-1 and VCAM-1 – Decreases vascular inflammation

  23. 5-7: Niacin Action in the Liver • Affects: hepatocyte • Targets: • Enzyme/receptor DGAT2 • Decreases triglyceride synthesis and Apo B secretion – Lowers VLDL and triglycerides, Apo B, and increases LDL particle size • Beta-chain ATP synthase • Lowers HDL catabolism – Increases lipoprotein A-1 and HDL2

  24. Toxicity • Short-term: • Vasodilation • Flushing • Burning in the face and hands • Nausea and vomiting *High dose is considered over 100mg per day • Long-term: • Hyperpigmentation • Abnormal glucose tolerance • Hyperuricemia • Peptic ulcers • Hepatomegaly • Jaundice

  25. Deficiency • Symptoms of mild deficiency: indigestion, fatigue, canker sores, vomiting, depression • Pellagra is associated with severe deficiency • Characterized by the four D’s: • Diarrhea • Dementia • Sun-sensitive dermatitis • Even death • Associated with AIDS, alcohol abuse, anorexia nervosa, cancer patients

  26. Pellagra Continued • “Casals Necklace” • Widespread in Europe in the 18th century • High incidence in SE states of the US During the early 20th century • associated with new imports of corn from Europe • Any guesses why? • Led to fortification of nicotinic acid and tryptophan in many foods www.odermatol.com

  27. Forms of Niacin as Supplements • Niacin used to treat: • Hartnup’s disease, poor glucose tolerance, IDDM, atherosclerosis, schizophrenia, hyperlipidemia, skin disorders • *Lipid soluble derivative of nicotinic acid for hyperlipidemia • Niacinamide used for: • Chemotherapy and also IDDM • Tablet or capsule • Regular or extended-released (fewer side effects but increased risk of liver damage) • *When supplementing with niacin, it is recommended that liver function tests be performed periodically

  28. Clinical Interactions • Antibiotics (tetracycline) • Aspirin • Anti-seizure medication • Anti-coagulants (blood thinners) • Blood pressure medications (Alpha-blockers) • Cholesterol-lowering medications • Statins • Diabetes medications • Isoniazid (INH) • Nicotine patches

  29. Take Away • Niacin supplies NAD+ to be reduced to NADH • Deficiencies lead to Pellagra • Niacin can improve cardiovascular health by increasing HDL and lowering LDL

  30. References • Brandt, Mark. “Vitamins and Coenzymes.” Chemistry and Biochemistry. Rose-Hulman Institute of Technology, n.d. Wed. 18 Nov. 2013. <http://www.rose-hulman.edu/~brandt/Chem330/Vitamin.pdf>. • “B-Vitamins and Folate.” Eat Right. Academy of Nutrition and Dietetics, n.d. Web. 17 Nov. 2013. <http://eatright.org/Public/content.aspx?id=6793>. • Creider JC, Hegele RA, Joy TR. Niacin: another look at an underutilized lipid-lowering medication. Nat Rev Endocrinol. 2012;8(9):517-28. • Kamanna VS, Kashyap ML. Mechanism of action of niacin. Am J Cardiol. 2008;101(8A):20B-26B. • Lavigne PM, Karas RH. The current state of niacin in cardiovascular disease prevention: a systematic review and meta-regression. J Am CollCardiol. 2013;61(4):440-6. • “New Lowdown on Cholesterol.” Havard Health Publications. Havard Medical School, n.d. Web. 18 Nov. 2013. <http://www.health.havard.edu/newsweek/New_lowdown_on_cholesterol.htm>. • “Niacin.” Medline Plus. National Institutes of Health, n.d. Web. 19 Nov. 2013. <http:/www.nlm.nih.gov/medlineplus/ency/article/002409.htm>. • “Niacin.” NMS Labs. Tox Wiki, n.d. Web. 20 Nov. 2013. <http://toxwiki.wikispaces.com/Niacin>. • Rhodes T, Norquist JM, Sisk CM, et al. The association of flushing bother, impact, treatment satisfaction and discontinuation of niacin therapy. Int J ClinPract. 2013;67(12):1238-46. • “Vitamin B3 (Niacin).” University of Maryland Medical Center. N.p., 20 June 2013. Web. 17 Nov. 2013. <http://umm.edu/health/medical/altmed/spplement/vitamin-b3--niacin>. • Zempleni J, Rucker RB, McCormick DB, Suttie JW. (2007) Handbook of Vitamins, pp. 1-570. CRC Press, Boca Raton FL.

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