Vitamin B6 refers to a group of 3-hydroxy-2-methylpyridine derivatives including pyridoxine, pyridoxal, pyridoxamine, and pyridoxic acid. These colorless, water-soluble compounds are stable in dry and solution forms. Pyridoxine is oxidized to the active form pyridoxal, whose aldehyde group allows it to react with amino acids via Schiff base formation. This reaction labilizes other bonds on the bound carbon, serving as the basis for pyridoxal and pyridoxamine's catalytic roles.

1. Chemical and physical
properties of pyridoxine
Domina Petric, MD

2. Essential features of the chemical
structure:
Derivative of 3-hydroxy-2-
methyl-5-hydroxypyridine
Phosphorylatable
5-hydroxymethyl group
Substituent at ring carbon para to
the pyridine nitrogen must be
metabolizable to an aldehyde.
April 17, 2018
Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
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3. Chemical structures of vitamin B6
R Name
CH2OH Pyridoxine
CHO Pyridoxal
COOH Pyridoxic acid
CH2NH2 Pyridoxamine
April 17, 2018
Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
3

4. Nomenclature
• Vitamin B6 is the generic descriptor for all
3-hydroxy-2-methylpyridine derivatives.
• The term pyridoxine is the trivial designation
of one vitamin B6-active compound
(3-hydroxy-4,5-bis(hydroxymethyl)-2-
methylpyridine), which was formerly called
adermin or pyridoxol.
• The biologically active analogs of pyridoxine
are the aldehyde pyridoxal and the amine
pyridoxamine.
April 17, 2018
Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
4

5. Chemical and physical properties
Vitamers B6 are colorless
crystals at room temperature.
Each is very soluble in water, weakly
soluble in ethanol and either
insoluble or sparingly soluble in
chloroform.
Each is fairly stable in dry form
and in solution.
April 17, 2018
Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
5

6. Chemical and physical properties
• Pyridoxine is oxidized in vivo and
under mild oxidizing conditions in
vitro to yield pyridoxal.
• The prominent feature of the
chemical reactivity of pyridoxal is
the ability of its aldehyde group to
react with primary amino groups (of
amino acids) to form Schiff bases.
April 17, 2018
Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
6

7. Chemical and physical properties
The electron-withdrawing effect
of the resulting Schiff base
labilizes the other bonds on the
bound carbon, thus serving
as the basis of the catalytic roles
of pyridoxal and pyridoxamine.
April 17, 2018
Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
7

8. Literature
• Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
April 17, 2018 8