CHEMISTRY AND PHYSIOLOGICAL
SIGNIFICANCE OF NIACIN
CHEMISTRY AND PHYSIOLOGICAL
SIGNIFICANCE OF NIACIN
PRESENTATION BY
PRABAKARAN.A
I-M.PHARM (PHARMACEUTICALCHEMISTRY)
SUBJECT: CHEMISTRY OF NATURAL PRODUCTS
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CHEMISTRY OF NATURAL PRODUCTS - VITAMINS, Summaries of Pharmaceutical Chemistry
THE TOPIC COVERS THE CHEMISTRY OF NIACIN ITS BIOCHEMICAL ROLE IN OUR DAY TO DAY LIFE .THIS ALSO CLEARLY STATES ITSB PHYSILOGICAL SIGNIFICANCE AND DEFICIENCY DISEASES IF NOT INCLUDED IN OUR DIET
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CHEMISTRY AND PHYSIOLOGICAL
SIGNIFICANCE OF NIACIN
CHEMISTRY AND PHYSIOLOGICAL
SIGNIFICANCE OF NIACIN
PRESENTATION BY
PRABAKARAN.A
I-M.PHARM (PHARMACEUTICALCHEMISTRY)
SUBJECT: CHEMISTRY OF NATURAL PRODUCTS
Definition of Vitamins
The term vitamin refers to an essential dietary factor
that is required by an organism in small amounts and
whose absence results in deficiency diseases.
Nicotinic acid (Niacin)
- Niacin (nicotinic acid and the amide derivative nicotinamide) is
one of the water soluble B-vitamins.
- (^) In the blood, brain, kidney and liver it is converted to the
coenzymes nicotinamide adenine dinucleotide (NAD) and
nicotinamide adenine dinucleotide phosphate (NADP), both of
which are involved in the generation of energy in cells.
- Tryptophan is an amino acid which is a provitamin of niacin.The
term niacin is the official name of the vitamin nicotinic acid.
- (^) The biochemically active form of vitamin niacin is the amide,
nicotinamide or niacinamide.
- (^) Niacin is pyridine derivative (pyridine -3-carboxylic acid)
3
2
4
N
1
5
6
7
O
9
OH
8
N i c o t i n i c A c i d [ P l a n t f o r m ]
3
2
4
N
1
5
6
7
O
9
NH 2
8
N i c o t i n a m i d e [ A n i m a l f o r m ]
[ r e d u c e d f o r m ]
Chemistry
Nicotinic acid is zwitterionic in nature; at high pH it is negatively
charged at the carboxylic function, while at low pH it is positively
charged at the pyridinyl nitrogen. Thus it is considered an amphoteric
molecule because it forms salts with acids as well as bases
Both nicotinic acid and nicotinamide are very stable in dry form ;
in solution nicotinamide is hydrolysed by acids and bases to yield
nicotinic acid.
Essential features of the
chemical structure
- (^) Pyridine nucleus substituted with a β-carboxylic acid
or a corresponding amine.
- (^) Pyridine nitrogen must be able to undergo reversible
oxidation/reduction (quaternary pyridinium ion
to/from tertiary amine).
Pyridine carbons adjacent to the nuclear nitrogen
atom must be open
pyridinium ion
The liver can synthesize niacin from essential aminoacid
tryptophan
60 mg of tryptophan can form 1mg of niacin.
Synthesis of niacin from tryptophan also requires pyridoxine,
riboflavin and iron.
Biosynthesis of Niacin
Dietary Sources
- (^) Liver
- Lean meat,eggs and dried
yeast
- Unrefined grains
- (^) Cereals
- Milk is poor source, but
has tryptophan.
- (^) Maize has niacin tightly
bound form not available.
Biochemical Functions
A sufficient intake of vitamin B3 (niacin) is important as
it helps the body to
- (^) convert food into glucose
- (^) used to produce energy
- (^) produce macromolecules, including fatty acids and
cholesterol
DNA repair and stress responses.
- (^) Maintenance of normal skin and mucous membranes
Functions
- Niacin is required by all cells.
- (^) It plays a vital role in the release of energy from all energy
yielding nutrients-CHO, fat, protein, alcohol.
- (^) Also required for the synthesis of protien, fat & 5C sugars needed
for the formation of DNA & RNA.
- (^) The biochemical role of niacin is to form part of coenzymes NAD
& NADP require by many of the key pathways of the metabolism.
- (^) Coenzymes NAD and NADPH are electron carriers of cells. NAD is
primarily involve in catabolic reactions whereas, NADP functions
mainly in anabolic reactions. They are coenzymes for more than
200 enzymes reactions.
Functions
Niacin in the form of NADP is involved in the
following:
- Glucose-6-PO4 to 6-Phospho gluconolactone in
HMP stunt.
- 6-phospho gluconate to 3 keto-6 phosphogluconate
in HMP stunt.
Thus they play an important role in mechanisms for
DNA repair and gene stability and therefore
influence cancer risk.
Deficiency
- (^) Pellagra – rare in Western societies.
Nervousness
irritability
Fatigue
- (^) Head ache
- (^) Insomnia
Mental depression
References
- (^) Chemistry of Natural Products: Sujata V. Bhat, B.A.
Nagasampagi, Meenakshi Sivakumar Springer Science
& Business Media, 04-Jan-2005 - Science - 840 pages
Organic Chemistry Natural Products-Vol- I by O.P.
Agarwal
B Vitamins and Folate : Chemistry, Analysis, Function
and Effects Edited by Victor R. Preedy ; The Royal
Society of Chemistry 2013 ;Published by the Royal
Society of Chemistry, www.rsc.org