Niacin

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Niacin

Systematic name	3-Pyridinecarboxylic acid
Chemical formula	C₆H₅NO₂
Molecular mass	123.11 g/mol
Melting point	236.6 °C
Boiling point	> 238°C @ 760 mm Hg (decomposes)
CAS number	[59-67-6]
SMILES	xxxx
Disclaimer and references

"Nicotinic acid" redirects here. For the drug found in tobacco products, see nicotine.

Niacin, also known as nicotinic acid or vitamin B3, is a water-soluble vitamin whose derivatives such as NADH, NAD, NAD⁺, and NADP play essential roles in energy metabolism in the living cell and DNA repair.<ref>Northwestern University Nutrition</ref> The designation vitamin B3 also includes the amide form, nicotinamide or niacinamide, whose chemical formula is C6H6N2O.

1 Deficiency and Overdose
2 Discovery
3 Bioavailability
4 Biosynthesis
5 Food Sources
6 Other uses
- 6.1 Industrial use
7 References
8 External links

[edit] Deficiency and Overdose

Severe lack of niacin causes the deficiency disease pellagra, wherein a mild deficiency slows down the metabolism decreasing cold tolerance. Extemely high doses of Niacin can cause niacin maculopathy, a thickening of the macula and retina which leads to blurred vision and blindness. <ref>JD Gass, Nictonic Acid Maculopathy, Am. J. Opthamology, 1973;76:500-10</ref> The recommended daily allowance of niacin is 2-12 mg a day for children, 14 mg a day for women, 16 mg a day for men, and 18 mg a day for pregnant or breast-feeding women.<ref>Jane Higdon, "Niacin", Micronutrient Information Center, Linus Pauling Institute</ref> Over 20mg per day may produce hot flushes lasting 15-30 minutes in duration.

[edit] Discovery

Nicotinic acid was first discovered from the oxidation of nicotine. When the properties of nicotinic acid were discovered, it was thought prudent to choose a name to dissociate it from nicotine and to avoid the idea that either smoking provided vitamins or that wholesome food contained a poison. The resulting name 'niacin' was derived from nicotinic acid + vitamin. Vitamin B3 is also referred to as "vitamin PP", a name derived from the obsolete term "pellagra-preventing factor."

[edit] Bioavailability

The liver can synthesize niacin from the essential amino acid tryptophan (see below), but the synthesis is extremely slow; 60 mg of tryptophan are required to make one milligram of niacin.^{[citation needed]} Dietary niacin deficiency tends to occur only in areas where people eat corn, the only grain low in niacin, as a staple food, and that don't use lime during maize (corn) meal/flour production. Alkali lime releases the tryptophan from the corn so that it can be absorbed in the gut, and converted to niacin.<ref name=UMM>Vitamin B3 University of Maryland Medical Center.</ref>

[edit] Biosynthesis

The 5-membered aromatic heterocycle of the essential amino acid, tryptophan, is cleaved and rearranged with the alpha amino group of tryptophan into the 6-membered aromatic heterocycle of niacin. By the following reaction:

Tryptophan --> Kynurenine --> 3-hydroxy kynurenine* --(B6 enzyme needed)--> Niacin

(*) from this intermediary xanthurenic acid is formed

Image:Nicotinic acid biosynthesis2.png

[edit] Food Sources

Animal products:	Fruits and vegetables:	Seeds:	Fungi:
liver, heart and kidney chicken fish: tuna, salmon milk eggs	leaf vegetables broccoli tomatoes carrots dates sweet potatoes asparagus avocados	nuts whole grain products legumes saltbush seeds	mushrooms brewer's yeast

[edit] Other uses

Niacin plays an important role in the production of several sex and stress-related hormones, particularly those made by the adrenal gland. It is also plays a role in removing toxic and harmful chemicals from the body.<ref name=UMM/> There is evidence that doses of 500-1000mg can terminate a bad trip on LSD, a synthetic indole, or enhance the MDMA experience. ^{[citation needed]}

Niacin, when taken in large doses, increases the level of High density lipoprotein (HDL)or "good" cholesterol in blood, and is sometimes prescribed for patients with low HDL, and at high risk of heart attack.<ref>Postgraduate Medicine</ref> Niacin (but not niacinamide) is also used in the treatment of hyperlipidemia because it reduces Very low density lipoprotein (VLDL), a precursor of Low density lipoprotein (LDL) or "bad" cholesterol, secretion from the liver, and inhibits cholesterol synthesis.<ref>Katzung and Trevors Pharmacology Examination and Board Review 7th edition, Authors: Trevor, Anthony J. Katzung, Bertram G. and Masters, Susan B., Lange Medical Books/ McGraw-Hill 2005</ref>

Niacin in itself is not toxic, but the chemicals converted by niacin are toxic to the skin and liver in overdose, and high doses of niacin should only be reached with gradual increase. Studies in laboratory animals have demonstrated behavioral changes when large doses of niacin are given.<ref>Sullivan, WT (June 10, 1958). "Behavioral changes in rats and guinea pigs induced by the administration of indole 3-acetic acid and 6-aminonicotinamide". The Journal of Nutrition: 199-209. Retrieved on September 4, 2006.</ref>

[edit] Industrial use

Nicotinic acid reacts with hemoglobin and myoglobin in meat to form a brightly coloured complex, and thus has been used as a food additive, typically to improve the colour of minced (ground) meat. Niacin is licensed as a food colouring agent in some countries.

[edit] References

[edit] External links

Link page to external chemical sources.

Vitamins
Retinol (A) \| B vitamins (Thiamine (B₁), Riboflavin (B₂), Niacin (B₃), Pantothenic acid (B₅), Pyridoxine (B₆), Biotin (B₇), Folic acid (B₉), Cyanocobalamin (B₁₂)) \| Choline \| Ascorbic acid (C) \| Ergocalciferol and Cholecalciferol (D) \| Tocopherol (E) \| Naphthoquinone (K)