Chemistry Reference
In-Depth Information
described below, these oligosaccharides are considered to play a significant
role in the protection of human neonates against infection by pathogenic
microorganisms. It is likely that, because of their immaturity, human neo-
nates are relatively susceptible to infection by pathogenic microorganisms;
the presence of significant amounts and a large variety of milk oligosacchar-
ides may therefore be advantageous insofar as they supplement the other,
known, anti-infection properties of the milk/colostrum. In this connection, it
is notable that the milk of species, such as monotremes, marsupials and a few
species of eutherians, including Ursidae, that produce very altricial neonates,
also contain relatively high concentrations of oligosaccharides, with lesser
amounts of free lactose (Messer and Urashima, 2002).
The 93 human milk oligosaccharides, the structures of which have been
determined to date, can be grouped into 12 series based on their core units as
in Table 8.2 (Haeuw-Fievre et al., 1993). The many variations of the oligo-
saccharides are constructed by the addition of a Neu5Ac
2-3/2-6 residue to
Gal or GlcNAc, and of Fuc
1-2/1-3/1-4 to Gal, GlcNAc or a reducing Glc of
the core units.
Table 8.2
The 12 core structures of human milk oligosaccharides
Abbreviation
Oligosaccharide
1
Lactose
Gal(
1-4)Glc
2
Lacto-N-tetraose
Gal(
1-3)GlcNAc(
1-3)Gal(
1-4)Glc
3
Lacto-N-
neotetraose
Gal(
1-4)GlcNAc(
1-3)Gal(
1-4)Glc
4
Lacto-N-hexaose
Gal(
β
1-4)GlcNAc(
β
1-6)
Gal(
β
1-4)Glc
Gal(
β
1-3)GlcNAc(
β
1-3)
5
Lacto-N-
neohexaose
Gal(
β
1-4)GlcNAc(
β
1-6)
Gal(
β
1-4)Glc
Gal(
β
1-4)GlcNAc(
β
1-3)
6
para-Lacto-N-
hexaose
Gal(
1-3)GlcNAc(
1-3)Gal(
1-4)GlcNAc(
1-3)Gal(
1-4)Glc
7
para-Lacto-N-
neohexaose
Gal(
1-4)GlcNAc(
1-3)Gal(
1-4)GlcNAc(
1-3)Gal(
1-4)Glc
8
Lacto-N-octaose
Gal(
β
1-4)GlcNAc(
β
1-3)Gal(
β
1-4)GlcNAc(
β
1-6)
Gal(
β
1-4)Glc
Gal(
β
1-3)GlcNAc(
β
1-3)
(Continued )
