Optimization of synthetic conditions for the preparation of dihomo-γ-linolenic acid from γ-linolenic acid

Article abstract of DOI:10.1007/s11746-008-1320-0

Orthogonal experiments were employed to optimize the correlated parameters of reduction, sulfonation, substitution and hydrolysis. These reactions were used to convert γ-linolenic acids into dihomo-γ-linolenic acids (DGLA). For the reduction, the best rea

Full text of DOI:10.1007/s11746-008-1320-0

J Am Oil Chem Soc (2009) 86:77–82
DOI 10.1007/s11746-008-1320-0
ORIGINAL PAPER
Optimization of Synthetic Conditions for the Preparation
of Dihomo-c-Linolenic Acid from c-Linolenic Acid
Gang Xue Æ Fengxia Liu Æ Ying Wang Æ
Kaixun Huang
Received: 19 April 2008 / Revised: 1 November 2008 / Accepted: 3 November 2008 / Published online: 26 November 2008
Ó AOCS 2008
Abstract Orthogonal experiments were employed to
optimize the correlated parameters of reduction, sulfona-
tion, substitution and hydrolysis. These reactions were used
to convert c-linolenic acids into dihomo-c-linolenic acids
(DGLA). For the reduction, the best reaction conditions
were at 35 °C for 4.5 h with LiAlH4 and c-linolenic acid
(in the ratio of 40 g:100 g); for the sulfonation, reaction at
29 °C for 3.5 h with 150 g c-linolenic alcohol and 65 mL
mesyl chloride, then the water phase being extracted with
dichloromethane (3 9 100 mL); for the substitution, the
reaction at 80 °C for 2.5 h with metallic sodium and sul-
fonate (at a ratio of 8 g:100 g); and for the hydrolysis,
reaction at 80 °C for 2.5 h with NaOH and dihomo dioate
(at a ratio of 50 g:100 g). The four reactions gave yields
that exceeded 90% for each step. Finally, crystallization
and decarboxylation provided DGLA in an overall yield of
60% and [95% purity.
Abbreviations
AA
Arachidonic acid
DGLA Dihomo-c-linolenic acid
DHA
EPA
GLA
PGE1
PGE2
I
Docosahexenoic acids
Eicosapentaenoic acid
c-Linolenic acid
Prostaglandin E1
Prostaglandin E2
c-Linolenic alcohol
c-Linolenic sulfonate
Dihomo dioate
II
III
IV
Dihomo dioic acid
Introduction
Lipids supply most of the nonglucose fuel calories and they
are building blocks for cellular components and essential
fatty acids [1]. Long-chain polyunsaturated fatty acids,
such as eicosapentaenoic acid (EPA), arachidonic acid
(AA), docosahexenoic acids (DHA) and dihomo-c-linolenic
acid (DGLA), mainly prevalent in fish oils, have been
demonstrated to play important roles in human health and
nutrition [2].
Keywords Dihomo-c-linolenic acid (DGLA) ꢀ
Reduction ꢀ Sulfonation ꢀ Substitution ꢀ Hydrolysis ꢀ
Crystallization and decarboxylation reaction ꢀ
Orthogonal experiment
DGLA is a precursor for the biosynthesis of prosta-
glandin E1 [3, 4]. It has been reported that DGLA and
DGLA-containing oil (triacylglycerol) might inhibit the
activity of thromboxane A2 [5], suppress human platelet
aggregation and mitogen release, and exert anti-inflam-
matory [6], antihypertensive [7], antiatherosclerotic, and
antiallergic effects [8, 9]. In the human body, these
essential and immunoregulatory long-chain omega-6 fatty
acids are only available from dietary sources [10, 11]. As a
precursor to the synthesis of DGLA, c-linolenic acid (GLA,
G. Xue ꢀ K. Huang
Huazhong University of Science and Technology,
430074 Wuhan, Hubei, People’s Republic of China
G. Xue (&) ꢀ F. Liu ꢀ Y. Wang
Department of Biological and Chemical Engineering,
Nanyang Institute of Technology, 80 Changjiang Road,
473004 Nanyang, Henan, People’s Republic of China
e-mail: gangxue1@sina.com.cn
123

78
J Am Oil Chem Soc (2009) 86:77–82
Gas Chromatography Analysis of GLA and DGLA
18:3n-6) is a key molecule participating in omega-6 fatty
acid metabolism which leads to the rapid production of
longer chain omega-6 fatty acids such as DGLA (20:3n-6),
AA (20:4n-6), PGE1 and PGE2, etc. [12].
A mixture sample containing 0.1 g DGLA or GLA and
2 mL 0.5 M solution of KOH in methanol was heated at
63 °C for 20 min with stirring, and 0.2 mL solution of BF3
in diethyl ether was then added. After heating for 5 min,
the mixture was cooled and extracted by using 2 mL
petroleum ether from which 2 lL of the upper solution was
taken out as the sample. Then the GC-14B gas chroma-
It has also been reported that DGLA could be synthe-
sized by microbes [13, 14], but the content of DGLA in
hyphae was too low to make it a precursor for the syn-
thesis of PGE1. Sun Qiliang reported that DGLA could be
synthesized chemically [15] with the purity of DGLA
ranged from 80 to 90% and a yield of 35 to 42%. And
Hong et al. also reported an improved method for the
preparation of c-linolenic acid and synthesis of dihomo-c-
linolenic acid, in which they used complex-sodium boron
hydride to reduce the methyl ester of c-linolenic acid, and
then to prepare dihomo-c-linolenic acid by methyl sulfo-
nyl chloride-malonic ester synthesis with a purity of 66%
[16].
tography (HITACHI) set using
a capillary column
(INNOWAX 19095 N-123) was heated. When the tem-
peratures of the column, detector and injector of the set
reached 230, 280 and 250 °C, respectively, the sample was
injected into the GC set. In the process of analysis, the
nitrogen carrier gas flow rate was set at 15 mL/min, the air
flow rate at 400 mL/min and the hydrogen flow rate at
50 mL/min. The purity of GLA or DGLA was calculated
by the integral area normalization method.
Base on previous research, in this study, an orthogonal
experiment was used to find the optimum correlated
parameters for reduction, sulfonation, substitution and
hydrolysis reactions in the synthesis of DGLA, such as the
reaction time, temperature and so on, and synthesize
DGLA with a purity exceeding 95% and an overall yield of
60% under these optimized conditions.
Typical Procedure for the Preparation of DGLA
Figure 1 shows a typical procedure for synthesizing DGLA
from GLA in a six-step reaction sequence.
Reduction
The reduction of GLA by LiAlH4 was carried out in a
three-neck flask. First, 60 g LiAlH4 (*1.5 mol/L) was
added to 2,750 mL diethyl ether to form a mixture which
was heated up to 35 °C, stirred for 1–1.5 h, and then cooled
below 25 °C, 150 g GLA (*0.55 mol/L) was added
dropwise into the flask with stirring and aerating N2 as a
protective gas, and after the mixture was raised to 35 °C
for refluxing 4–4.5 h, the flask was cooled down below
10 °C in an ice water bath and 250 mL ice water was
added; finally, the resultant I was extracted with diethyl
ether (3 9 100 mL) and following the evaporation of
diethyl ether, I was obtained.
Experimental Procedures
Materials
98% GLA was produced in our laboratory. It is isolated
from evening primrose oil by urea inclusion crystallization
[17]. LiAlH4, 2,4,6-trimethylpyridine and mesyl chloride
were purchased from China Fluka company. The standard
sample of DGLA was purchased from China Jilin Provin-
cial Institute for Drug Control. All chemicals and solvents
used were of analytical grade. Distilled and deionized
water was used throughout the whole experiment.
Fig. 1 Synthesis of DGLA
from GLA
123

J Am Oil Chem Soc (2009) 86:77–82
Sulfonation
79
stirring and aerating with N2 as a protective gas. Then the
temperature of the mixture was lowered to 50 °C and the
oil phase separated out after the adjustment of the pH
value to about 2–3 by 6 mol/L H2SO4. The resultant water
phase was extracted with diethyl ether. Then all the di-
ethyl ether phases containing oil were combined and
washed with water until a pH value of about 6 was
obtained. Following the evaporation of the diethyl ether,
IV was obtained.
A
470-mL amount of dichloromethane, 150 g
I
(*0.57 mol/L) and 86 mL 2,4,6-trimethylpyridine
(*0.7 mol/L) were added one after the other to a 3-L
three-neck flask. The flask was cooled down in the ice
water bath to below 2 °C and then 65 mL mesyl chloride
(*0.55 mol/L)was added. The reaction was performed at
26–29 °C for 4–4.5 h with stirring and aerating with N2 as
a protective gas. After that, the temperature of the flask was
cooled down to 4 °C, and 300 mL distilled water was
added. Next, 4 mol/L HCl was used to adjust the pH value
of the solution to about 1–2. The dichloromethane phase
was isolated and the water phase was extracted with
dichloromethane (3 9 100 mL). The extraction method
was designed at three levels (C1 means Method 1, in which,
the dichloromethane phase containing II was washed five
times with 1 mol/L HCl, and all the aqueous phases were
discarded. After dichloromethane was evaporated, II was
obtained. C2 means Method 2, in which, the process was
repeated as in Method 1 except that the aqueous phases
derived from the first and second washing were extracted
with dichloromethane. And C3 means Method 3. The
process was similar to Method 1, but the aqueous phases
derived from the first to the third washing were extracted
by using dichloromethane). The dichloromethane phases
were combined and washed to neutrality with 1 mol/L HCl
and water. Following the evaporation of dichloromethane,
II was obtained.
The yield of the products obtained from the above
procedures was calculated as follows:
The actual weight of the product ðgÞ
The yield ¼
The theoretical weight of the product (g)
ꢁ 100%
ð1Þ
Crystallization and Decarboxylation
The petroleum ether was added to IV in the volume ratio of
3:1, then the mixture was cooled to -20 °C for 24 h and
the impurities of the crystallized products were removed by
washing with cool petroleum ether. Decarboxylation at
150–160 °C for 3 h in an oil bath under vacuum gave
DGLA. The calculation of the yield from GLA to DGLA
was expressed as follows:
The actual weight of DGLA ðgÞꢁits purity ð%Þ
The yield ¼
The weight of GLA (g) ꢁ its purity ð%Þ
ꢁ100%
ð2Þ
Statistical Analysis [18]
Substitution
Statistical evaluations of the differences among the dif-
ferent treatments were calculated by the analysis of
variance software (ANOVA) with SPSS10.0 (Statistical
Program for Social Sciences), Chinese Version. Differ-
ences were considered significant at the 5 and 1% levels.
III was prepared by dissolving 22 g metallic sodium
(*1 mol/L) in 1,050 mL dehydrated alcohol below 18 °C
for 15 min with stirring and aerating N2 as a protective gas
and then adding 240 mL diethyl malonate (*1.5 mol/L)
and refluxing at 80 °C for 1–1.5 h. Next, the temperature of
the solution was cooled to 30–40 °°C and 195 g sulfonate
(*0.6 mol/L) was added. After the mixture was refluxed at
80 °C for 2 h, the temperature of the flask was dropped to
50 °C and 700 mL water was added. 4 mol/L HCl was
used to adjust the pH value of the mixture to 1–2, the oil
phase was separated, and the water phase was extracted
with petroleum ether (3 9 100 mL). Finally, all the
petroleum ether phases containing oil were combined and
washed by water until a pH value of 5–6. Following the
evaporation of the petroleum ether, III was obtained.
Results and Discussion
The Reduction of GLA
An L9(34) orthogonal experiment [19] was employed for
optimizing such technical parameters such as factor
A-reaction time (A1 = 3.5 h, A2 = 4 h, A3 = 4.5 h), factor
B-reaction temperature (B1 = 25 °C, B2 = 30 °C,
B3 = 35 °C), and factor C-the amount of LiAlH4 added to
per 100 g GLA (C1 = 40 g, C2 = 50 g, C3 = 60 g). The
results shown in Table 1 indicate that the optimal sequence
and combination were B–A–C and A3B3C3, respectively, by
the range analysis. The results of variance analysis are
listed in Table 2 which indicates that the effect of factors A
and B on the yield revealed a significance at 5% level.
Hydrolysis
A mixture containing 220 g III (*0.54 mol/L) and 95 g
NaOH (*0.42 mol/L) in 870 mL water and 1,800 mL
ethanol was hydrolyzed at 80 °C for refluxing for 2 h with
123

80
J Am Oil Chem Soc (2009) 86:77–82
Sulfonation of the Product I
Table 1 The results of orthogonal experiment for reduction, sulfo-
nation, substitution and hydrolytic reactions
The influences of the reaction time, temperature and
extraction method on the yield of sulfonation of the product I
were investigated by employing an L9(34) orthogonal
experiment, in which levels of the main factors were as fol-
lows: reaction time A (A1 = 3.5 h, A2 = 4 h, A3 = 4.5 h),
No. Factor
Aa
Yield
Dd Ee
Bb
Cc
Ff
Gg
Hh
1
1
1
1
2
2
2
3
3
3
1
2
3
1
2
3
1
2
3
1
2
3
2
3
1
3
1
2
1
2
3
3
1
2
2
3
1
67.58 90.87 91.23 86.24
85.21 95.55 94.06 89.25
91.22 97.78 94.28 89.67
75.36 92.45 95.71 91.04
95.37 97.45 96.33 92.33
96.56 93.36 93.31 89.25
86.25 95.89 95.54 91.03
95.89 93.66 93.59 90.22
98.22 96.75 96.75 92.33
Reduction
2
reaction temperature
B
(B1 = 23 °C, B2 = 26 °C,
3
B3 = 29 °C) and extraction method C (see the ‘‘Experi-
mental Procedures’’). The results of range analysis indicate
that the optimal sequence of C–B–A and the optimal com-
bination of A3B3C3, and the results of the variance analysis,
shown in Table 2, indicate that the effect of factors B and C
on the yield revealed significant at 5 and 1% level, respec-
tively. As factors B and C should be controlled at optimal
level, therefore, the optimal combination was A1B3C3. The
experiment was performed at 29 °C for 3.5 h with Method 3.
The yield of product II exceeded 95%.
4
5
6
7
8
9
k1
k2
k3
k1
k2
k3
k1
k2
k3
k1
k2
k3
a–d
81.34 76.40 86.68
89.10 92.16 86.26
93.45 95.33 90.95
94.73 93.07 92.63
94.42 95.55 94.92
95.43 95.96 97.04
93.19 94.16 92.71
95.12 94.66 95.51
95.29 94.78 95.38
88.39 89.44 88.57
90.87 90.60 90.84
91.16 90.42 91.01
Optimal sequence: B–A–C
Optimal combination: A3B3C3
Sulfonation
Pyridine with strong basicity usually acted as an acid-
binding agent. In sulfonation, 2,4,6-trimethylpyridine was
added to absorb HCl. After the absorption, 2,4,6-trimethyl-
pyridine was neutralized by adding excess HCl. During the
experiment, when eluting the dichloromethane phase using
1 mol/L HCl, we found that the colors of the eluted
aqueous phases from the first to the third time were all
yellowish, which meant the aqueous phases had to be
extracted with dichloromethane one more time.
Optimal sequence: C–B–A
Optimal combination: A3B3C3
Substitution
Optimal sequence: C–A–B
Optimal combination: A3B2C2
Hydrolysis
Optimal sequence: A–C–B
Optimal combination: A3B2C3
Factor A, B, C, and D (black). For reduction (A-reaction time,
B-reaction temperature, C-the amount of LiAlH4 added to per 100 g
GLA); For sulfonation (A-reaction time, B-reaction temperature,
C-extraction method); For substitution (A-reaction time, B-reaction
temperature, C-the amount of added metallic sodium); For hydrolysis
(A-reaction time, B-reaction temperature, C-the amount of NaOH
added to per 100 g III)
Substitution of the Product II
For the substitution of the product II, the influences of the
reaction time, temperature and amount of added metallic
sodium on the yield were investigated by employing an
L9(34) orthogonal experiment, in which reaction time is
factor A (A1 = 1.5 h, A2 = 2 h, A3 = 2.5 h), reaction
e–f
The yield of reduction, sulfonation, substitution and hydrolytic
reaction products
temperature is factor
B3 = 90 °C), and for per 100 g II, the amount of added
metallic sodium is factor (C1 = 5 g, C2 = 8 g,
B
(B1 = 80 °C, B2 = 85 °C,
Therefore, factors A and B should be controlled at the
optimal level and factor C held at any level, i.e. A3B3C1.
With this combination, the experiment was performed at
35 °C for 4.5 h with 40 g LiAlH4 added into per 100 g
GLA. The yield of I exceeded 90%.
C
C3 = 11 g). The result of range analysis in Table 1 shows
the optimal sequence was C–A–B and the optimal combi-
nation was A3B2C2, and the variance analysis of Table 2
indicated the effect of factors A and C on the yield was
significant at 5%. Therefore, factors A and C should be
controlled at the optimal level and factor B may at any
level, i.e. A3B1C2. The experiment was carried out at 80 °C
for 2.5 h with 8 g metallic sodium added per 100 g II. The
yield of the III exceeded 95%.
The final products of the reduction might include I,
LiOH, Al (OH)3, LiAlO2, which were the proportional to
GLA and LiAlH4. A sediment of Al(OH)3 produced in the
reduction was granular but amorphous. When the product I
was directly extracted with diethyl ether, the yield obtained
was rather low, because I could be included in the sedi-
ment, similar to a urea inclusion complex. Thus, in order to
destroy the crust of the inclusion, it was necessary to wash
the sediment repeatedly with water till I was released. Then
I was able to be extracted with diethyl ether from the water
phase.
For substitution, studies were made of the influences
on the experimental results by the reaction time and
temperature of both metallic sodium with ethanol and
diethyl malonate with sodium ethoxide. At lower tem-
peratures, metallic sodium took a long time to dissolve in
ethanol. As soon as it was dissolved, if diethyl malonate
123

J Am Oil Chem Soc (2009) 86:77–82
81
Table 2 The results of variance analysis
Source
df
SS
S2
F
Sig.
df
SS
S2
F
Sig.
Reduction
Sulfonation
A
2
2
2
2
8
226.012
617.066
40.337
8.824
113.066
308.533
20.169
4.412
25.614*
69.631*
4.571
0.038
0.014
0.179
2
2
2
2
8
1.615
0.808
6.338
0.136
0.017
0.009
B
14.706
29.185
0.255
7.353
14.593
0.127
57.712*
C
114.533**
Error
Total variance
892.239
45.762
Substitution
Hydrolysis
A
2
2
2
2
8
8.167
0.649
4.084
0.324
7.492
0.163
24.987*
1.985
0.038
0.335
0.021
2
2
2
2
8
14.163
7.082
1.174
5.639
0.213
33.214*
5.505
0.029
0.154
0.036
B
2.347
11.278
0.426
C
14.983
0.327
45.839*
26.447*
Error
Total variance
24.126
28.215
* Significant at the 5% level
** Significant at the 1% level
was added immediately and the temperature was raised
simultaneously, a turbid or white precipitate was sure to
appear, which meant the experiment had failed. The
reason was probably that metallic sodium could not be
completely used up in reacting with ethanol. When die-
thyl malonate was added, the residual sodium played the
role of a catalytic agent and led to the failure of experi-
ments. If there was N2 present in the reaction system, the
catalytic action of sodium could be accelerated. For this
reason, diethyl malonate could not be added in the reac-
tion system until the metallic sodium had completely
reacted with the ethanol. When diethyl malonate was
added below 20 °C for over 20 min, all the experiments
were successful. Therefore, the reaction between sodium
ethoxide and diethyl malonate should be below 20 °C for
20 min, and at the same time, the doses of sodium and
diethyl malonate should be strictly controlled to avoid the
white precipitate.
80 °C for 2.5 h with 50 g NaOH added to per 100 g III.
The yield of product IV exceeded 90%.
The Effect of Crystallization Times and Separation
Method on the Yield and Purity
Crystallization of IV was carried out at -10 °C for 24 h
after petroleum ether was added to it at a volume ratio of
3:1. The crystallized products were able to be separated by
vacuum filtration and washing with chilled petroleum ether
(Method 1), or by centrifugation and washing with chilled
petroleum ether (Method 2). The processes might have to be
repeat several times. In each method, all the petroleum ether
phases were combined and concentrated. Then new petro-
leum ether was added to the concentrated products in the
volume ratio of 2:1, and the mixture was recrystallized three
times in the same manner as mentioned above. Decarbox-
ylation was carried out at 150 °C for 3 h under vacuum
conditions. Following this step, DGLA was obtained.
The effects of the times and methods of crystallization
on the purity and yield are shown in Table 3 and variance
analysis indicated that the effects of the crystallization
times and separation methods on the purity did not dem-
onstrate significant at the 5% level, while the effects of the
crystallization times and methods on the yield were sig-
nificant at the 1% level. Therefore, in terms of the yields,
variance analysis and Duncan’s Test indicated that crys-
tallization three times with Method 2 was the optimal
choice.
Hydrolysis of the Product III
An L9(34) orthogonal experiment was employed to opti-
mize the technical parameters—factor A-reaction time
(A1 = 1.5 h, A2 = 2 h, A3 = 2.5 h), factor B-reaction
temperature (B1 = 80 °C, B2 = 85 °C, B3 = 90 4C), and
factor C-the amount of NaOH added to per 100 g III
(C1 = 30 g, C2 = 40 g, C3 = 50 g). The results, listed in
Table 1, indicate that the optimal sequence was A–C–B and
the optimal combination was A3B2C3 by range analysis.
And the results of variance analysis in Table 2 indicates
that the effect of factors A and C on the yield were sig-
nificant at the 5% level. Therefore, factors A and C should
be controlled at the optimal level and factor B may at any
level, i.e. A3B1C3, thus the experiment was performed at
In summary, from the results and analyses by L9(34)
orthogonal experiment, we concluded that when all the
optimal conditions mentioned above were adopted for
synthesizing DGLA, the purity of DGLA could exceed
95% with an overall yield of 60%.
123

82
J Am Oil Chem Soc (2009) 86:77–82
Table 3 The effects of the time and method of crystallization on the purity and yield
Crystallization times
Purity
Yield
Method 1 (B1)
Method 2 (B2)
Method 1 (B1)
Method 2 (B2)
One time (A1)
Two times (A2)
Three times (A3)
95.89
94.97
96.04
95.02
95.63
96.26
94.67
96.22
96.11
95.13
95.37
94.66
46.36
48.25
53.44
54.63
55.25
56.33
58.64
56.25
63.43
62.57
65.37
64.63
Purity of DGLA, yield using GLA as starting materials to synthesize DGLA
Acknowledgments This work was supported by the Nanyang
Institute of Technology. We thank Nanyang Pukang Groups Chemical
Medicine Mill for providing financial support.
10. Stone KJ, Willis AL, Hart M, Kirtland SJ, Kernoff PBA, McNicol
GP (1978) The metabolism of dihomo-c-linolenic acid in man.
Lipids 11:801–803
11. Chapkin FY (1992) Mouse peritoneal macrophage prostaglandin
E1 synthesis is altered by dietary gamma-linolenic acid. Nutrition
122:1600–1606
12. Harbige LS, Layward L, Morrs-Downes MM, Dumonde DC,
Amor S (2000) The protective effects of omega-6 fatty acids in
experimental autoimmune encephalomyelitis (EAE) in relation to
transforming growth factor-beta 1 (TGF-b1) up-regulation and
increased prostaglandin E2 (PGE2) production. Clin Exp Immu-
nol 122:445–452
13. Maaike MB, Dooper W, Wassink L, Rabetl YM, Graus F (2002)
The modulatory effects of prostaglandin-E on cytokine production
by human peripheral blood mononuclear cells are independent of
the prostaglandin subtype. Immunology 107:152–159
14. Shimizu S, Akimoto K, Kawashima H, Shinmen Y, Yamada H
(1989) Production of dihomo-c-linolenic acid by Mortierella
alpina 1S–4. J Am Oil Chem Soc 2:237–241
15. Sun QL (1995) Measurement of the relative content of DGLA
and synthesized intermediates by using thin-layer scanning sys-
tem. J N Bethune Univ Med Sci 21:427–428
16. Ying H, Chen GW, Song H, Yu H, Wu QY (1987) Improved
methods of preparation of c-linolenic acid and synthesis of
dihomo-c-linolenic acid. Shenyang Yaoxueyuan Xuebao 4:275–
278
17. Liu FX, Xue G, Gao QH, Gao WX, Zhang LH (2005) Study on
the encapsulation technique of c-linolenic acid—single factor,
and two-factor tests for encapsulation process. China J Chinese
Materia Medica 6:433–435
18. Lu WD (2000) SPSS for Windows—statistical analysis.
Publishing House of Electronics Industry Press, Beijing
19. Xue G, Guo SX (2004) Design of optimizing experiment and
Statistical analysis. Publishing House of Hubei province Press,
Wuhan
References
1. Geert JA, Wanten Philip CC (2007) Immune modulation by
parenteral lipid emulsions. Am J Clin Nutr 85:1171–1184
2. Johnathan A, Napier JA, Olga S, Baoxiu Q, Colin ML (2004)
Progress toward the production of long-chain polyunsaturated
fatty acids in transgenic plants. Lipids 39:1067–1075
3. Hamberg M (1976) Biosynthesis of prostaglandin E1 by human
seminal vesicles. Lipids 3:249–250
4. LamacIka M, Sajbidor J (1997) Biotechnological production of
prostaglandins. Appl Microbiol Biotechnol 47:199–206
5. Smith DL, Willis AL, Nguyen N, Conner D, Zahedi S, Fulks J
(1989) Eskimo Plasma Constituents, Dihomo-c-linolenic acid,
Eicosapentaenoic acid and Docosahexenoic acid inhibit the
release of atherogenic mitogens. Lipids 24:70–75
6. Kawashima H, Akimoto K, Higashiyama K, Fujikawa S, Shimizu
S (2000) Industrial production of dihomo-c-linolenic acid by a D5
desaturase-defective mutant of Mortierella alpina 1S–4 fungus1.
J Am Oil Chem Soc 77:1135–1139
7. Hassall CH, Kirtland SJ (1984) Dihomo-c-linolenic acid reverses
hypertension induced in rats by diets rich in saturated fat. Lipids
9:699–703
8. Hassam AG, Crawford MA (1978) The incorporation of orally
administered radiolabeled dihomo-c-linolenic acid (20:3x6) into
rat tissue lipids and its conversion to arachidonic acid. Lipids
11:801–803
´
9. Cao JM, Blond JP, Juaneda P, Durand G, Bezard J (1995) Effect
of low levels of dietary fish oil on fatty acid desaturation and
tissue fatty acids in obese and lean rats. Lipids 9:825–832
123