Synthesis of a triantioxidant compound: Combination of β-apo-8′-carotenoic acid, selenacapryloic acid and trolox in a triglyceride

Article abstract of DOI:10.1016/S0009-3084(01)00164-5

Carotenoids, vitamin-E and selenium show similar or complementary physiological properties and protect against a variety of pathological processes. Mixtures of these antioxidants are found in nutritional supplements and are used to prevent several diseases. The synthetic connection of carotenoids, vitamin-E and selenium may increase the chemopreventive activity of the individual compounds. A carotenoic acid, a selena fatty acid and the vitamin-E derivative trolox were successively esterified with glycerol to 1-(β-apo-8′carotenoyl)-2-(7-selenaoctanoyl)-3-(6-hydroxy-2,5,7, 8-tetramethylchroman-2-acyl)-glycerol. This triantioxidant compound revealed, in the DPPH (1,1-diphenyl-2-picrylhydrazyl) test, an additive affect, consisting of the radical quenching activity of the carotenoid and trolox. The DPPH test was not sensitive for the Se moiety in the triantioxidant compound.

Full text of DOI:10.1016/S0009-3084(01)00164-5

Chemistry and Physics of Lipids
112 (2001) 59–65
www.elsevier.com/locate/chemphyslip
Synthesis of a triantioxidant compound:
combination of b-apo-8%-carotenoic acid,
selenacapryloic acid and trolox in a triglyceride
Trine Naalsund a,*, Karl Egil Malterud b, Vassilia Partali a,
Hans-Richard Sliwka a
a Norges Teknisk Natur6itenskapelige Uni6ersitet, Institutt for Kjemi, N-7491 Trondheim, Norway
b Uni6ersitet Oslo, Farmasøytisk Institutt — A6deling for Farmakognosi, N-0316 Oslo, Norway
Received 1 December 2000; received in revised form 10 May 2001; accepted 15 May 2001
Abstract
Carotenoids, vitamin-E and selenium show similar or complementary physiological properties and protect against
a variety of pathological processes. Mixtures of these antioxidants are found in nutritional supplements and are used
to prevent several diseases. The synthetic connection of carotenoids, vitamin-E and selenium may increase the
chemopreventive activity of the individual compounds. A carotenoic acid, a selena fatty acid and the vitamin-E
derivative trolox were successively esterified with glycerol to 1-(b-apo-8%carotenoyl)-2-(7-selenaoctanoyl)-3-(6-hydroxy-
2,5,7,8-tetramethylchroman-2-acyl)-glycerol. This triantioxidant compound revealed, in the DPPH (1,1-diphenyl-2-
picrylhydrazyl) test, an additive effect, consisting of the radical quenching activity of the carotenoid and trolox. The
DPPH test was not sensitive for the Se moiety in the triantioxidant compound. © 2001 Elsevier Science Ireland Ltd.
All rights reserved.
Keywords: Antioxidants; Carotenoids; Condensation reactions; Selenium; Structured lipids; Vitamin E
Tappel, 1993; Chen et al., 1993). An epidemiolog-
ical investigation has verified that the combina-
1. Introduction
tion, particularly of vitamin-E, b-carotene and
Several antioxidants together provide increased
selenium (from selenium yeast), reduced the risk
protection against toxic processes (Chen and Tap-
of cancer (Blot et al., 1993). The combined appli-
pel, 1996). Thus, the mutual administration of
cation of these three antioxidants is suggested for
vitamin-E, selenium and b-carotene offers a more
effective prophylaxis than the individual com-
pounds alone (Tominga et al., 1992; Chen and
the treatment of certain diseases (Rombi, 1993;
Sokol, 1997). Mixtures of selenium, b-carotene
and vitamin-E are available as food supplements
(PolyANTOX). The close proximity of different
antioxidants can be of importance for their activ-
* Corresponding author.
ity (Young and Gregoriadis, 1996). Chalcogen
0009-3084/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved.
PII: S0009-3084(01)00164-5

60
T. Naalsund et al. / Chemistry and Physics of Lipids 112 (2001) 59–65
modified lipids may be used to prepare self-assem-
bled monolayers on noble metal surfaces (Ulman,
1996; Ion et al., 2001).
spectra the characteristic molecular ion of 12 was
detected, in accordance with the calculated iso-
tope pattern. The UV/VIS spectra of 12 resembled
1
that of carotenoic ester 9. In the H NMR spectra
We describe here the synthesis of a derivative,
which contains three biologically important an-
tioxidants covalently bound to the physiologically
active carrier molecule glycerol. Monoantioxidant
and diantioxidant glycerides have previously been
synthesized (Hoving et al., 1975; Weithmann et
al., 1994; Morizaki and Ozaki, 1996; Partali et al.,
1996; Larsen et al., 1998).
the glycerides 6, 10 and 12 displayed the distinct
patterns of the mono-, di- and triglyceryl protons
(Haraldsson et al., 1995) and the carbon atoms of
the glyceryl backbone in these compounds pre-
sented the characteristic shift values in the 13C
NMR spectra (Chapman and Gon˜i, 1994).
Several methods are employed for the charac-
terization of the radical quenching activity of
individual antioxidant compounds. Nevertheless,
a reliable technique which determines concur-
rently the activity of different kinds of antioxi-
dants has not yet been developed (Pryor et al.,
1993). A widely used assay measures the scaveng-
ing of the DPPH (1,1-diphenyl-2-picrylhydrazyl)
radical (Bondet et al., 1997). The results obtained
with DPPH are in good agreement with more
biologically related assays such as peroxidizing of
lipids in viable hepatocytes (Malterud et al.,
1993). The DPPH test has already been adopted
to determine the antioxidant activity of
carotenoids (Nomura et al., 1997) and retinoids
(Yamanu and Ito, 1998). However, the apo-
carotenoate 9 reacted considerably slower with
DPPH than trolox (11), (Fig. 1). The 50%-in-
hibitor concentration (IC50) for trolox (11) was
found to be 30 mM and for triglyceride 12 23 mM,
(Fig. 1). The improved value for 12 resulted
mainly from the addition of the inhibitor activity
of C30-ester 9 and trolox (11). Thus, the antioxi-
dant activity of carotenoid 9 and trolox (11) is not
influenced by esterification with glycerol. The
DPPH test was not sensitive for the selenium
moiety in 12: selenaoctanoate 4 did not react with
the DPPH radical. However, in sunflower oil oxi-
dation tests selenadodecylglycerol-1-ether acts
synergistically with vitamin E (Yanishlieva et al.,
2001a). Also, carotenoic acid 7, ester 9 and 1-b-
apo-8%-carotenoylglycerol prevented synergisti-
cally with vitamin E, sunflower oil oxidation
(Yanishlieva et al., 2001b). So far, the combina-
tion of vitamin E with vitamin A or C has re-
sulted in few compounds with increased effects
(Suetsugu et al., 1994; Makishima et al., 1998).
Other antioxidant-glyceride derivatives such as to-
copheryl-ascorbyl- or BHT (butylated hydroxy-
2. Results
The synthesis of regio-isomerically pure unsym-
metrical triglycerides implies that the constituents
(here vitamin-E, carotenoid, selenium) occur as
‘fatty’ acids. For the carotenoid we selected the
naturally occurring and synthetically available
apocarotenoic acid 7 (Bauernfeind, 1972). Trolox
(11) stood for the vitamin-E part of the molecule
(Cynshi et al., 1995). The selenium containing
segment came from selenacaprylic acid 2 ( Lie,
1993).
7-Selenaoctanoyl chloride (3), obtained from
7-selena-caprylic acid (2) by reaction with oxalyl
chloride, (Wood et al., 1944) reacted with benzyli-
deneglycerol (1) (Mattson and Volpenheim, 1962;
Serdarevich, 1967) to selenaoctanoyl benzyli-
deneglycerol (5) (Scheme 1). [Direct esterification
(Neises and Steglich, 1978) of selenaacid 2 with
the protected glycerol 1 formed only traces of 5.]
The opening of the acetal 5 with isomerization
preventing triethylborate (Martin, 1953; Ser-
darevich, 1967) gave 2-selenaoctanoyl-glycerol (6)
in 11% yield. Carotenoyl chloride 8, prepared
from acid 7 with oxalylchloride, reacted with
monoglyceride 6 to 1,2-diglyceride 10, which, with
trolox (11), DMAP and DCC (Kodali, 1987)
formed the triantioxidant triglyceride 12 in 24%
yield. 2-Monoglycerides and 1,2-diglycerides such
as 6 and 10 easily convert into other positional
isomers (Sjursnes and Anthonsen, 1994;
1
Boswinkel et al., 1996). However, the H NMR
spectra, recorded directly after the work-up proce-
dure, indicated no significant acyl migration for 6
and 10 (Sonnet and Dudley, 1994). In the mass

T. Naalsund et al. / Chemistry and Physics of Lipids 112 (2001) 59–65
61
toluene)-glycerides show, at best, the same activity
as one of the single antioxidant component, with
DPPH even an antagonistic effect was observed
(Weithmann et al., 1994; Morizaki and Ozaki,
1996). 3-Retinoyl ascorbate is only half as active
in the DPPH-test as vitamin-A or vitamin-C in its
radical inhibitor capacity (Yamanu and Ito,
1998). Triglyceride 12 represents a combined an-
tioxidant-carotenoid derivative, where an additive
effect was found by a radical test. Whether the
triantioxidant-triglyceride 12 will be active in vivo
has still to be demonstrated.
Scheme 1.

62
T. Naalsund et al. / Chemistry and Physics of Lipids 112 (2001) 59–65
Fig. 1. Decrease of DPPH with ethyl apocarotenoate 9, trolox (11) and triglyceride 12. 50%-inhibiting concentration: 11 IC50=30
mM, 12 IC50=23 mM.
3. Experimental
3.2. 7-Selenaoctanoic acid (2)
3.1. General
2 was prepared according to Lie (1993). Recrys-
tallisation of the crude product from hexane at 20
°C gave 2 at a yield of 70%.
After reaction the products were adsorbed on
silicagel, dried in vacuo and separated by flash
chromatography (silica 60, Merck). If necessary,
separation was also carried out on preparative or
analytical TLC plates with heptane–acetone mix-
tures. The peaks of the mass spectra (EI, IP 70
eV, 220 °C) are related to 80Se. Small yields of
carotenoid compounds were determined from the
VIS spectra in CH2Cl2 (Davies, 1976). For the
determination of DPPH scavenging (Malterud et
al., 1993) the test substances, dissolved in DMSO
(50 ml), were added to a methanolic solution of
DPPH (2.95 ml) The DPPH concentration was
sufficient to give an A517 of 1). The mixture was
stirred for a few seconds and the decrease in
absorbance was measured over a 15 min period.
Percentage scavenging was calculated as 100×
(A0−At)/A0, where A0 is the initial absorbance
and At the absorbance at time t. The values are
corrected for dilution factors, absorption of apo-
carotenoid and of the DPPH reaction product
diphenylhydrazine.
3.3. 2-(7-Selenaoctanoyl)-1,3-benzylidenglycerol
(5)
To a solution of 7-selenaoctanoylchloride (3)
[prepared from acid 2 with oxalylchloride (Wood
et al., 1944)] (2.2 g, 9.5 mmol) in CH2Cl2 (6 ml)
was added, under a N2-atmosphere, 1,3-benzyli-
deneglycerol (Mattson and Volpenheim, 1962) (1)
(2.1 g, 11.4 mmol) in dry CHCl3 (4 ml) and
pyridin (4 ml). The solution was stirred for 48 h at
room temperature (Martin, 1953). Extraction with
CH2Cl2 and chromatographic work-up with hep-
tane:acetone 7:3 afforded 5 (cis and trans 1:2) (2.4
g, 68%), whose formation was confirmed by spec-
tral data from MS, 1H NMR and 13C NMR
(Serdarevich, 1967).
3.4. 2-(7-Selenaoctanoyl)-glycerol (6)
To 2-selenaoctanoyl-1,3-benzylidenglycerol
5

T. Naalsund et al. / Chemistry and Physics of Lipids 112 (2001) 59–65
63
MS: m/z 698 [M+, Se isotopic pattern], 606
[M+—92 (toluene), Se isotope pattern], 505 [M+
—193 (Se acylium)], 488 [M+—210 (Se acid)], 413
[606–193 (Se acylium)], 432 [C30 acid], 267 [M+—
431 (C30 acid -H, Se isotopic pattern)].
(1.5 g, 4 mmol), dissolved in triethyl-borate (15 ml),
finely powdered boric acid (0.78 g, 12.4 mmol) was
added. The mixture was stirred for 5 min at 100 °C.
The solvent was evaporated (100 °C, 2–5 Torr) and
heating under vacuum continued for 10 min. Di-
ethylether (50 ml) was added, the ether solution was
washed four times with 20 ml portions of H2O,
dried over Na-sulfate and the ether evaporated
under vacuum at 25 °C (Martin, 1953). Chromato-
graphic work-up of the residue with hep-
tane:acetone 6:4 afforded 6 (61 mg, 11% based on
reacted 5). C10H20O4Se, 28.1% Se.
1H NMR (400 MHz, CDCl3): glycerol part
(ABMXY system) l=4.35 and 4.40 (both d×d,
2H, C1), 3.77–3.78 (m, 2H, C3), 5.17 (qui, 1H, C2);
selenaoctanoyl part: d=2.54 (t, 2H, C6), 2.38 (t,
2H, C2), 1.99 (s, 3H, Se-CH3), 1.60–1.78 (m, 4H,
C3, C5), 1.40–1.50 (m, 2H, C4); carotenoyl part
l=1.03 (s, 6H, 2×CH3, C1), 1.40 (m, 2H, C2),
1.59 (s, 2H, C3), 1.72 (s, 3H, CH3, C5), 1.98 (s, 12H,
4×CH3, polyene chain), 6.15–6.73 (m, 12H,
polyene chain).
MS: m/z 284 [M+], 210 [M+—74 (propandiol),
Se isotopic pattern], 193 [M+—91 (glycerol-H), Se
1
isotopic pattern]. H NMR (300 MHz, d-acetone,
immediately recorded after work-up procedure):
glycerol part (A2A2% × system) l=3.71 and 3.65
13C NMR (100 MHz, CDCl3): glycerol part
l=72.3 (C2), 62.2 (C1), 61.5 (C3); selenaoctanoyl
part l=173.6 (C=O, C1), 33.9 (C2), 29.7 (C5),
29.2 (C4), 25.1 (C6), 24.4 (C3), 4.0 (Se–CH3);
carotenoyl part l=168.4 (C=O), 122.8–141.3
(16C, polyene chain), 39.6 (C2), 34.3 (C1), 33.1
(C4), 29.0 (2×CH3, C1), 20.8 (CH3, C5), 19.2 (C3),
13.0 (4×CH3, polyene chain). A 13C NMR spectra
recorded after several weeks indicated substantial
acyl migration.
(both dxd, 2H, A C1, C3, 2H, A% C1, C3, JAA%
=
11.6, JAX=6.4 Hz), 4.88 (qui, 1H, C2, Jax=6.4
Hz); selenaoctanoyl part l=2.55 (t, 2H, C6), 2.33
(t, 2H, C2), 1.96 (s, 3H, Se–CH3), 1.57–1.75 (m,
4H, C3, C5), 1.37–1.50 (m, 2H, C4).
-C13C NMR (100 MHz, d-acetone): glycerol part
l=61.5 (C1, C3), 76.3 (C2); selenaoctanoyl part
l=173.5 (C=O), 34.7 (C2), 32.0 (C5), 30.6 (C4),
25.4 (C6), 25.2 (C3), 3.5 (Se–CH3).
3.7. 1-(i-Apo-8%-carotenoyl)-2-(7-selenaoctanoyl)
-3-(6-hydroxy-2,5,7,8-tetramethylchroman-2-
acyl)-glycerol (12)
3.5. i-Apo-8%-carotenoic acid chloride (8)
To an ice cold solution of apocarotenoic acid 7
(3.0 g, 6.9 mmol) in CCl4 (20 ml) was added, under
N2 atmosphere, oxalylchloride (0.7 ml, 8.3 mmol).
The mixture was heated at 70 °C for 24 h. The
solvent and excess oxalylchloride were evaporated
under reduced pressure (Wood et al., 1944). The
residual acid chloride 8 was used without further
purification.
To a solution of 1-apocarotenoyl-2-selenaoc-
tanoyl-glycerol 10 (32 mg, 0.046 mmol) and trolox
(11) (30 mg, 0.12 mmol) in CH2Cl2 (4 ml) was
added, under N2 atmosphere, dicyclohexylcarbodi-
imide (55 mg, 0.3 mmol) and 4-dimethylaminopy-
ridin (32 mg, 0.3 mmol) (Kodali, 1987). The
mixture was stirred for 5 h at room temperature.
Chromatographic work-up with heptane:acetone
4:6 afforded 12 (10 mg, 24%). C54H74O8Se, 8.5% Se.
VIS: umax=458 nm.
3.6. 1-(i-Apo-8%-carotenoyl)-2-(7-selenaoctanoyl)-
glycerol (10)
MS: m/z 930 [M+, Se isotopic pattern], 838
[M+ —92 (toluene), Se isotopic pattern)], 737 [M+
—193 (Se acylium)], 588 [838-250 (trolox), Se
isotopic pattern], 515 [M+—415 (C30 acylium), Se
isotopic pattern)], 499 [M+—431 (C30 acid -H, Se
isotopic pattern)], 432 [C30 acid], 250 [trolox].
1H NMR (400 MHz, CDCl3): glycerol part
l=4.21 and 4.40 (both d×d, 4H, C1, C3),?5.22
To an ice cold solution of apocarotenoyl chloride
(8) (93 mg, 0.2 mmol) in CH2Cl2 was added, under
N2 atmosphere, 2-selenaoctanoyl-glycerol 6 (61 mg,
0.2 mmol) and pyridine (0.2 ml). The mixture was
stirred at 40–45 °C for 3 h. Extraction with CH2Cl2
and chromatographic work-up with hex-
ane:acetone 6:4 afforded 10 (47 mg, 31%).
C40H58O5Se, 11.4% Se.

64
T. Naalsund et al. / Chemistry and Physics of Lipids 112 (2001) 59–65
Chen, H., Tappel, A.L., 1996. Protection of multiple antioxi-
dants against heme protein oxidation and lipid peroxida-
tion induced by CBrCl3 on liver, lung, kidney, heart and
spleen. J. Agric. Food Chem. 44, 854–858.
Chen, H., Pellet, L.J., Andersen, H.J., Tappel, A.L., 1993.
Protection by vitamin E, selenium and b-carotene against
oxidative damage in rat liver slices and homogenate.
Free Rad. Biol. Med. 14, 473–482.
Cynshi, O., Takashima, Y., Katoh, Y., Tamura, K., Sato,
M., Fujita, Y., 1995. Action of phenolic antioxidants on
various active oxygen species. J. Biolum. Chemolum. 10,
261–269.
Davies, B.H., 1976. Carotenoids. In: Goodwin, T.W. (Ed.),
Chemistry and Biochemistry of Plant Pigments. Aca-
demic Press, London, pp. 149–155.
(m, 1H, C2); trolox part l=1.25 (s, 3H, CH3,
C2a), 2.17 (s, 3H, CH3, C5a), 2.15 (s, 3H, CH3,
C7a), 2.10 (s, 3H, CH3, C8b), 1.86 (m, 1H, C3),
2.46 (m, 1H, C3), 2.60 (m, 2H, C4); selenaoc-
tanoyl and carotenoyl part in accordance with
10.
13C NMR (100 MHz, CDCl3): glycerol part
l=68.8 (C2), 62.5 (C3), 62.0 (C1); trolox part
l=173.7 (C=O), 145.5 (C6), 30.7 (C3), 21.9
(CH3, C2a), 12.3 (CH3, C7a), 11.8 (CH3, C8b),
11.3 (CH3, C5a); selenaoctanoyl and carotenoyl
part in accordance with 10.
8
8
Haraldsson, G.G., Gudmundsson, B.O., Almarsson, O.,
1995. The synthesis of homogenous triglycerides of eicos-
apentanoic acid and docosahexanoic acid by lipase. Te-
trahedron 51, 941–952.
Acknowledgements
Hoving, J., Valkema, A.J., Wilson, J.H.P., Woldring, M.G.,
1975. Properties of glycerol-75Se-triether: a lipid soluble
marker for the estimation of intestinal fat absorption.
Lab. Clin. Med. 86, 286.
Ion, A., Banica, F.G., Partali, V., Sliwka, H.R., 2001. Self-
assembled monolayers on the gold electrode surface.
New direction in electrochemistry, Symposium, Univer-
sity of Salford, April 2001.
We thank Dr Berhard Schulz, BASF AG,
Ludwigshafen, for samples of C30-acid and C30-
ester, N. Weber, H.P.-Kaufmann-Institut, Mu¨n-
ster, for seed crystals of benzylidenglycerol and
B. Olsrød for recording the mass spectra.
Kodali, D.R., 1987. Improved method for the synthesis of
1-acyl-sn-glycerol or 3-acyl-sn-glycerol. J. Lipid Res. 28,
464–469.
Larsen, E., Abendroth, J., Partali, V., Schulz, B., Sliwka,
H.-R., Quartey, E.G.K., 1998. Combination of vitamin E
with a carotenoid: a-tocopherol and trolox linked to b-
apo-8%-carotenoic acid. Chem. Eur. J. 4, 113–117.
Lie, M.S.F.L.K., 1993. The synthesis of rare and unusual
fatty-acids. Prog. Lipid. Res. 32, 151–194.
Makishima, M., Kamatani, Y., Honma, Y., Inomata, K.,
Kishiye, T., (Nisshin Flour Milling Co), 1998. Pharma-
ceutical composition for the treatment of Leukemia con-
taining 9-cis-retinoic acid alpha tocopherol ester 77%.
US 5827878.
Malterud, K.E., Farbrot, T.L., Huse, A.E., Sund, R.B.,
1993. Antioxidant and radical scavenging effects of an-
thraquinones and anthrones. Pharmacology 47 (Suppl. 1),
77–85.
References
Bauernfeind, J.C., 1972. Carotenoid vitamin A precursors in
food and feeds. J. Agr. Food Chem. 20, 456–473.
Blot, W.J., Li, J.-Y., Taylor, P.R., Guo, W., Sawsey, S.,
Wang, C.Q., Yang, C.S., Zheng, S.-F., Gail, M., Li, G.-
Y., Yu, Y., Liu, B, Tangrea, J., Sun, Y., Liu, F., Frau-
meni, J.F., Zhang, Y.-H., Li, B., 1993. Nutrition
intervention trials in Linxian, China. Supplementation
with specific vitamin mineral combinations, cancer inci-
dence, and disease specific mortality in the general popu-
lation. J. Natl. Cancer Inst. 85, 1483–1492.
Bondet, V., Brand-Williams, W., Berset, C., 1997. Kinetics
and mechanisms of antioxidant activity using the DPPH
free radical method. Lebens. Wiss. Technol. 30, 609–615.
Boswinkel, G., Derksen, J.T.P., van’t Riet, K., Cuperus,
F.P., 1996. Kinetics of acyl migration in monoglycerides
and dependence on acyl chain length. J. Am. Oil Chem.
Soc. 73, 707–711.
Martin, J.B., 1953. Preparation of saturated and unsaturated
symmetrical monoglycerides. J. Am. Chem. Soc. 75,
5482–5483.
Mattson, F.H., Volpenheim, R.A., 1962. Synthesis and prop-
erties of glycerides. J. Lipid Res. 3, 226–296.
Morizaki, K., Ozaki, S., 1996. Design of novel hybrid vita-
min C derivatives: thermal stability and biological activ-
ity. Chem. Pharm. Bull. 44, 1647–1655.
Neises, B., Steglich, W., 1978. Simple method for the ester-
ification of carboxylic acids. Angew. Chem. Int. Ed. 17,
522–525.
Chapman, D., Gon˜i, F.M., 1994. Physical properties: optical
and spectral characteristics. In: Gunstone, F.G., Har-
wood, J.L., Padley, F.B. (Eds.), The Lipid Handbook.
Chapman Hall, London, p. 516, 519.
Chen, H., Tappel, A.L., 1993. Protection of heme protein by
vitamin E, selenium, and b-carotene against oxidative
damage in rat heart, kidney, lung and spleen. Free Rad.
Biol. Med. 14, 183–190.

T. Naalsund et al. / Chemistry and Physics of Lipids 112 (2001) 59–65
65
Nomura, T., Kikuchi, M., Kubodera, A., Kawakami, Y.,
1997. Proton-donative antioxidant activity of fucoxanthin
with 1,1-diphenyl-2-picrylhydrazyl (DPPH). Biochem.
Mol. Biol. Internat. 42, 361–370.
Partali, V., Kvittingen, L., Sliwka, H.-R., Anthonsen, T.,
1996. Stable, highly unsaturated glycerides—enzymatic
synthesis with a carotenoid acid. Angew. Chem. Int. Ed.
35, 329–330.
antioxidant of tocopherylascorbyl phosphate. US 5306713.
Tominga, K., Saito, Y., Mori, K., Miyazawa, N., Yokui, K.,
Kogama, Y., Shimamura, K., Imura, J., Nagai, M., 1992.
An evaluation of serum microelement concentrations in
lung-cancer and matched non-cancer patients to determine
the risk of developing lung-cancer. A preliminary study.
Jpn. J. Clin. Oncol. 22, 96–101.
Ulman, A., 1996. Formation and structure of self-assembled
monolayers. Chem. Rev. 96, 1533–1554.
Weithmann, K.-U., Wess, G., Seiffge, D., (Hoechst AG), 1994.
Lipid-selective antioxidants and their preparation and use.
US 5318987.
The nutrition Farm, Polyionics Inc. Campton Kentucky,
USA.
Pryor, W.A., Cornicelli, J.A., Devall, L.J., Tait, B., Trivedi,
B.K., Witiak, D.T., Wu, M., 1993. A rapid screening-test
to determine the antioxidant potencies of natural and
synthetic antioxidants. J. Org. Chem. 58, 3521–3532.
Rombi, M., 1993. Use of b-carotene in the treatment of
asthma (Arkopharma SA). EP 542632.
Serdarevich, B., 1967. Glyceride isomerizations in lipid chem-
istry. J. Am. Oil Chem. 44, 381–393.
Sjursnes, B.J., Anthonsen, B., 1994. Acyl migration in 1,2-
dibutyrin. Dependence on solvent and water activity. Bio-
catalysis 9, 285–297.
Sokol, R.J., 1997. Use of antioxidants agents to treat
cholestatic liver disease.(University Technol. Corp.) WO
97/25864.
Sonnett, P.E., Dudley, R.L., 1994. Stereospecific synthesis of
selected triglycerides—comments on acyl migration and
analysis of configuration. Chem. Phys. Lipids 72, 185–191.
Suetsugu, K., Ogata, K., Yoshida, K., Uehara, K., Tomita,
K., (Shiseido Co, Senju Pharm. Co), 1994. Highly active
Wood, T.R., Jackson, F.L., Baldwin, A.R., Longenecker,
H.A., 1944. The preparation of some unsaturated fatty
acid chlorides. J. Am. Chem. Soc. 66, 287–289.
Yamanu, Y.Y., Ito, M., 1998. Synthesis of the 3-O-retinoyl-L-
ascorbic acid and related compounds: characterization and
reducing activity against DPPH. Heterocycles 47, 289–299.
Yanishlieva, N.V., Marinova, E.M., Raneva, V.G., Partali, V.,
Sliwka, H.R., in pressa. B-Apo-8%carotenoic acid and its
esters in sunflower oil oxidation. J. Am. Oil Chem. Soc. 32,
444.
Yanishlieva, N.V., Marinova, E.M., Raneva, V.G., Partali, V.,
Sliwka, H.R., submitted. 11-selenadodecylglyceryl-1-ether
in lipid autoxidation. J. Am. Oil Chem. Soc. 32, 444.
Young, A.M., Gregoriadis, G., 1996. Photolysis of retinol in
liposomes and its protection with tocopherol and oxyben-
zone. Photochem. Photobiol. 63, 344–352.
.