Biology Reference
In-Depth Information
yielding structures with double bonds adjacent to one another (conjugated double bonds).
Conjugated linoleic acid (CLA) is a mixture of such isomers (more than 28 have been found
to date) and has been used as a measure of free radical activity (see
Figure 4.1
). CLA also has
anti-bacterial properties and can even inhibit leukemic cell growth.
Awide variety of human health benefits have been reputed for the two long chain omega-3
PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In fact it is almost
impossible to find a single human affliction that has not been tested with EPA or DHA. Of
particular importance are various cancers, heart disease, and immunological and neurolog-
ical disorders
[12,13]
. Below are the ethyl esters of EPA (20:5
6
5,8,11,14,17
) and DHA
(22:6
6
4,7,10,13,16,19
), both of which are employed in enteral (tube-feeding) applications (see
Figure 4.2
).
Omega Designation
The omega nomenclature for fatty acids was proposed by R.T. Holman in 1964
[14]
.
This classification divides fatty acids into metabolic families reflecting how they were
synthesized biochemically. The system is based on location of the last double bond in the
chain, specifically how many carbons it is from the terminal or omega methyl group. The
terminal carbon is designated omega, n or
u
.
Figure 4.3
presents the 18-C sequence of fatty
O
HO
FIGURE 4.1
A conjugated linoleic acid (CLA, 18:2
D
9,11t
).
O
O
EPA: ethyl ester of eicosapentaenoic acid
O
O
DHA: ethyl ester of docosahexaenoic acid
FIGURE 4.2
EPA: Ethyl ester of eicosapentaenoic acid and DHA: Ethyl ester of docosahexaenoic acid.
