Biomarkers
1995). The gorgonian specimens harvested in colder waters conrained
high amounts of methylene-interrupted polyunsaturated fatty acids,
unlike specimens from warmer waters. This could have been due to
the temperature or to the high content of wax esters. Nevertheless,
arachidonic acid, a major component in all fatty acid mixtures studied
(14-21 %), is a well-known precursor of prostanoid compounds. The high
levels of tetracosapolyenoic acids in specimens from colder waters were
of particular interest: 24:6 (n-3) (5.1-5.3% ), 24:5 (n-6) (8.4-15.8% ) and
24:5 (n-3) (5.0-5.2%).
Methoxy fatty acids in lipids from a red alga
Methoxy fatty acids are not widespread in nature, though marine
sponges have been the source of new 2-methoxy acids. Several mid-chain
methoxy acids have been reported only in cyanobacteria and certain
microorganisms (Kornprobst & Barnathan, 1998).
Twenty-five fatty acids were identified in the total lipids of the red
alga Schizymenia dubyi including 2-hydroxy and 3-hydroxy acids (Barnathan et al., 1998). An interesting finding was the identification of
new 9-MeO-15:0, 9-MeO-17:0, 13-MeO-13-21:0 and 15-MeO-23:0
acids. Molecular ions were lacking, and the diagnostic fragment ions
corresponded to a cleavage on both sides of CH-OCH3 (A and B types),
followed by successive losses of methanol, as shown below.
Major diagnostic fragment ions (m/z) in the mass spectra of methoxy acid
methyl esters.
Fatty acids
m
n
A 1
A 2
A 3
B 1
B 2
9-MeO-15:0
7
5
201
169
137
129
97
9-MeO-17:0
7
201
169
137
157
125
13-MeO-21:0
11
7
257
223
193
157
125
15-MeO-23:0
13
7
285
253
221
157
125
Three of the new acids were probably formed by chain-elongation: the
11-MeO-19:0 acid was only found in Helicobacter pilori.
9-MeO-17:0 → 11-MeO-19:0
→ 13-MeO-21:0
→15-MeO-23:0
It can be assumed that the new methoxy acids arise from symbiotic bacteria, rather than cyanobacteria or diatoms since the specimens studied
were devoid of polyunsaturated fatty acids.
41
1995). The gorgonian specimens harvested in colder waters conrained
high amounts of methylene-interrupted polyunsaturated fatty acids,
unlike specimens from warmer waters. This could have been due to
the temperature or to the high content of wax esters. Nevertheless,
arachidonic acid, a major component in all fatty acid mixtures studied
(14-21 %), is a well-known precursor of prostanoid compounds. The high
levels of tetracosapolyenoic acids in specimens from colder waters were
of particular interest: 24:6 (n-3) (5.1-5.3% ), 24:5 (n-6) (8.4-15.8% ) and
24:5 (n-3) (5.0-5.2%).
Methoxy fatty acids in lipids from a red alga
Methoxy fatty acids are not widespread in nature, though marine
sponges have been the source of new 2-methoxy acids. Several mid-chain
methoxy acids have been reported only in cyanobacteria and certain
microorganisms (Kornprobst & Barnathan, 1998).
Twenty-five fatty acids were identified in the total lipids of the red
alga Schizymenia dubyi including 2-hydroxy and 3-hydroxy acids (Barnathan et al., 1998). An interesting finding was the identification of
new 9-MeO-15:0, 9-MeO-17:0, 13-MeO-13-21:0 and 15-MeO-23:0
acids. Molecular ions were lacking, and the diagnostic fragment ions
corresponded to a cleavage on both sides of CH-OCH3 (A and B types),
followed by successive losses of methanol, as shown below.
Major diagnostic fragment ions (m/z) in the mass spectra of methoxy acid
methyl esters.
Fatty acids
m
n
A 1
A 2
A 3
B 1
B 2
9-MeO-15:0
7
5
201
169
137
129
97
9-MeO-17:0
7
201
169
137
157
125
13-MeO-21:0
11
7
257
223
193
157
125
15-MeO-23:0
13
7
285
253
221
157
125
Three of the new acids were probably formed by chain-elongation: the
11-MeO-19:0 acid was only found in Helicobacter pilori.
9-MeO-17:0 → 11-MeO-19:0
→ 13-MeO-21:0
→15-MeO-23:0
It can be assumed that the new methoxy acids arise from symbiotic bacteria, rather than cyanobacteria or diatoms since the specimens studied
were devoid of polyunsaturated fatty acids.
41