300
Chapter 17 · Vital Amines - Vitamins
17
in the blood. This disease can be cured by supplementing vitamins B 9 and B 12 . Since folic acid
deficiency during pregnancy can lead to malformations, some countries, such as Switzerland, the
USA and Canada, have decided to add folic acid
to certain foods. EU countries have not yet taken
part in this measure.
17.2.9 Vitamin B 12 (Cobalamin)
The vitamin with the most complicated structure is vitamin B 12 (. Fig. 17.9). It contains a
cobalt atom in the oxidation state +III, which is
surrounded by a 15-membered ring system, the
corrin. Numerous rests are bound to this corrin
ring, including acetic acid and propionic acid
amides. One of these rests contains a nucleotide-bound 5,6-dimethylbenzimidazole which
coordinates with one of its two nitrogen atoms at
the cobalt atom. In addition, a group R is bound
to cobalt. In the vitamin B 12 itself, cyanocobalamin, R is a cyano group. There are also other
derivatives such as aquocobalamin (vitamin B 12a ,
R = H 2 O) or hydroxycobalamin (vitamin B 12b ,
R = OH − ).
HN
N
N
N
H 2 N
O
HN
N
H
O
COOH
COOH
H
Pteroic acid
Pteridine
ring
p -Aminobenzoic
acid
L-Glutamic acid
. Fig. 17.8 Structure of folic acid (vitamin B 9 )
Co
N
N
N
N
CH 3
CH 3
CH 3
O
NH 2
NH 2
O
CH 3
CH 3
NH 2
O
NH
O
O
CH 3
P
O
HO
O
O
HO
OH
N
N
CH 3
CH 3
O
H 2 N
H
H 3 C
H 3 C
H 2 N
O
H 2 N
O
R
CH 3
. Fig. 17.9 Structure of cobalamins (vitamin B 12 and
derivatives)