Synthesis and in vivo anti-inflammatory activity of long-chain 2-amino-alcohols

Article abstract of DOI:10.1016/S0960-894X(02)00939-3

The synthesis of optically pure long-chain 2-amino-alcohols and 1-O-dodecyl-2-deoxy-2-amino-sn-glycerol was carried out starting from L- or D-Boc-Ser(OBn)-ol by oxidation and consecutive Wittig reaction or etherification reaction. 2-Amino-oleyl alcohol wa

Full text of DOI:10.1016/S0960-894X(02)00939-3

Bioorganic & Medicinal Chemistry Letters 13 (2003) 375–377
Synthesis and In Vivo Anti-Inflammatory Activity of
Long-Chain 2-Amino-alcohols
Victoria Magrioti,a Dimitra Hadjipavlou-Litinab and Violetta Constantinou-Kokotoua,*
aChemical Laboratories, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece
bDepartment of Pharmaceutical Chemistry, University of Thessaloniki, 540 06 Thessaloniki, Greece
Received 19September 2002; revised 5 November 2002; accepted 6 November 2002
Abstract—The synthesis of optically pure long-chain 2-amino-alcohols and 1-O-dodecyl-2-deoxy-2-amino-sn-glycerol was carried
out starting from l- or d-Boc-Ser(OBn)-ol by oxidation and consecutive Wittig reaction or etherification reaction. 2-Amino-oleyl
alcohol was synthesized by reduction of the corresponding 2-amino-oleic acid. All the long chain amino-alcohols presented inter-
esting inhibition of carrageenin-induced paw edema in rats (ED50 from 0.017 to 0.010 mmol/kg).
# 2002 Elsevier Science Ltd. All rights reserved.
Introduction
convenient method for the synthesis of saturated long-
chain 2-amino-alcohols and O-alkyl ethers of 2-deoxy-
2-amino-glycerol starting from serine, the synthesis of
2-amino-oleyl alcohol and the in vivo study of their
anti-inflammatory and analgesic activity.
Sphingosine, (2S,3R,4E)-2-amino-4-octadecene-1,3-diol,
the lipid component that forms the structural back-
bone of all sphingolipids, has been shown to affect
the activity of many important signaling enzymes,
including serine/threonine protein kinases, phospholi-
pase A2, protein kinase C, protein phosphatase
activity, and specific kinases that phosphorylate the
epidermal growth factor (EGF) receptor.1À3 The bio-
logical significance of sphingosine has stimulated
much research on the synthesis of sphingosine ana-
logues and study of their bioactivity (for examples,
see refs 4–6).
Chemistry
Commercially available l-Boc-Ser(Bn)-OH was chosen
as starting material and the introduction of the long
chain was based on a Wittig olefination reaction of the
suitably protected serinal. Compound 1 was converted
into alcohol 2 by reduction of its corresponding mixed
anhydride with NaBH4 (Fig. 1).11 Alcohol 2 was oxi-
dized in a two-phase system by NaOCl in the presence
of a catalytic amount of 4-acetamido-TEMPO.17 It is
known that a-amino aldehydes present a high tendency
for racemization.18 However, it has been demonstrated
that the oxidation of amino alcohols by NaOCl/
TEMPO proceeds without racemization.19
Long-chain 2-amino alcohols are sphingosine analogues
that have been reported to present interesting in vitro
cytotoxicity,7 immunosuppressive activity8 and anti-
Leishmanicidal activity.9 Most recently it has been
demonstrated that long-chain amino-alcohol and dia-
mine derivatives induce apoptosis through a caspase-3
dependent pathway.10 Long-chain 2-amino-alcohols
may be prepared by reduction11,12 of chiral lipidic
a-amino acids13À15 and may be used for the synthesis of
long chain 1,2- and 1,3-diamines.16 We present here a
The resulting aldehyde was immediately treated with the
ylide, generated from tridecyl-triphenylphosphonium
bromide and KHMDS, in toluene at 0 ꢀC to afford the
unsaturated derivative 4. Under these reaction condi-
tions, a Z/E (6:1) mixture of isomers was obtained, as
shown by 1H NMR spectroscopic analysis. Catalytic
hydrogenation of the double bond of compound 4 with
simultaneous removal of benzyl group produced 2-(tert-
butoxycarbonylamino)-hexadecanol (5). After treat-
ment of 5 with 4N HCl/Et2O, (R)-2-amino-hexadecanol
hydrochloride (6) was obtained. (S)-2-Amino-hexadecanol
*Corresponding author. Tel.: +30-210-529-4261; fax: +30-210-529-
4265; e-mail: vikon@aua.gr
0960-894X/03/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S0960-894X(02)00939-3

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V. Magrioti et al. / Bioorg. Med. Chem. Lett. 13 (2003) 375–377
Figure 1. Synthesis of (R)-2-amino-hexadecanol.
Figure 3. Synthesis of (S)-2-amino-oleyl alcohol.
Figure 2. Synthesis of 1-O-dodecyl-2-deoxy-2-amino-sn-glycerol.
edema, induced by injection of 0.1 mL carrageenin 2%
(K100, commercially available) in sterilized saline
intradermally into the right footpad.24 The examined
compounds were administered ip simultaneously. Con-
trol animals accepted only vehicle. The experiment was
repeated twice to compare the mean value in 2-amino-
alcohols treated groups with that in groups of animals
that were injected only with saline. Drug activities were
expressed as percentage inhibition of edema formation
compared to controls.
was prepared by similar reactions, starting from d-Boc-
Ser(Bn)–OH.
The proposed synthetic method is free of racemization
as indicated by comparison of the value of specific
rotation for (R)-alcohol 5 {[a]D=À9.1 (c 1.0 in CHCl3)}
with that reported in the literature {[a]D=À8.5 (c 2.0 in
CHCl313}.
Protected serinol 2 is a chiral key-intermediate com-
pound for the synthesis of mono-ethers of 2-deoxy-2-
amino-glycerol structurally related to 2-amino alcohols
(Fig. 2). Treatment of compound 2 with dodecylbromide
in a biphasic system of benzene/aqueous sodium hydrox-
ide in the presence of a catalytic amount of Bu4NHSO4
afforded the ether derivative 7 in good yield. Catalytic
hydrogenation of 7 and treatment with 4N HCl/Et2O
yielded (S)-2-amino-3-dodecyloxy-propanol 9.
Analgesic activity
Acetic acid writhing test was used in rats.24 In groups of
five Fisher 344 female rats weighing 200–260 g, the title
compounds’ ED50 dose for the carrageenin test was
given ip and 30 min later 1 mL/100 g body weight of
0.6% acetic acid was given ip. After 5 min, the number
of stretches were counted each 5 min for a period of 30
min. The total number of writhes exhibited by each
animal in the group was recorded and compared to that
of the vehicle treated control group.
a-Amino oleic acid exhibits interesting properties and it
has been shown in in vivo studies to be a promising
anti-calcification agent.20 Recently, two synthetic pro-
cedures for the synthesis of enantiopure (S)-a-amino-
oleic acid 10 have been reported.21,22 Boc-protected
derivative 11 was prepared by treatment of 10 with di-
tert-butyl dicarbonate, and then was converted into
alcohol 12 by reduction of its corresponding mixed
anhydride with NaBH4 (Fig. 3).
Results and Discussion
To access the anti-inflammatory activity of 2-amino-
alcohols (R)-6, (S)-6, 9 and 12, the rat carrageenin-
induced paw edema assay was employed as a model for
acute inflammation and indomethacin was included as a
reference drug (47% inhibition at 0.011 mmol/kg),
whereas the acetic acid writhing test was used to assess
the analgesic activity in rats (sodium acetylsalicylate at 1
mmol/kg was administered as reference drug, 93.4%).
The ED50 values obtained from the in vivo data and the
results from the writhing test are summarized in Table
1. All compounds exhibited interesting inhibition of
paw edema and analgesic activity. It seems that the
stereochemistry does not influence the inhibition of
All products gave satisfactory analytical and spectroscopic
data in full accord with their assigned structures.23
In vivo studies.
Inhibition of carrageenin-induced paw edema in rats. The
experiment was conducted on Fisher 344 female rats
weighing 200–260 g. Acute anti-inflammatory activity was
measured after 3.5 h by reduction of rat paw carrageenin

V. Magrioti et al. / Bioorg. Med. Chem. Lett. 13 (2003) 375–377
377
Table 1. In vivo anti-inflammatory and analgesic activity of long
chain 2-amino-alcohols
8. Hirose, R.; Hamamichi, N.; Kitao, Y.; Matsuzaki, T.;
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Compd
ED50, mmol/kga
(R)-6
(S)-6
9
0.017 (72.6%)b
0.017 (89.2%)b
0.010 (95.6%)b
0.010 (88.1%)b
12
11. Kokotos, G. Synthesis 1990, 299.
aStatistical significance of results was established using the Student’s
t-test, P<0.001.
bAnalgesic activity for the corresponding doses.
12. Kokotos, G.; Noula, C. J. Org. Chem. 1996, 61, 6994.
13. Kokotos, G.; Padron, J. M.; Noula, C.; Gibbons, W. A.;
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14. Kokotos, G.; Martin, V.; Constantinou-Kokotou, V.;
Gibbons, W. A. Amino Acids 1996, 11, 329.
edema, since both enantiomers of 2-amino-hexadecanol
exhibited the same anti-inflammatory activity. (S)-6 Iso-
mer exhibited slightly better analgesic activity than (R)-6.
The replacement of a methylene group of the carbon
chain by an oxygen atom proved to enhance the inhibi-
tion of paw edema and the protection against the acetic
acid induced writhes (analgesic activity). The introduc-
tion of a cis double bond at C-9caused a similar effect.
(S)-2-Amino-3-dodecyloxy-propanediol (9) and (S)-2-
amino-oleyl alcohol (12) presented the same anti-
inflammatory activity (ED50 0.010 mmol/kg). In addi-
tion, both compounds 9 and 12 exhibited strong analgesic
activity at a dose of 0.010 mmol/kg corresponding to the
ED50 dose of the carrageenin paw edema test.
15. (a) Kokotos, G.; Padron, J. M.; Martin, T.; Gibbons,
W. A.; Martin, V. S. J. Org. Chem. 1998, 63, 3741. (b) Mar-
kidis, T.; Kokotos, G. J. Org. Chem. 2002, 67, 1685.
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Gibbons, W. A.; Roussakis, C. Bioorg. Med. Chem. Lett.
1998, 8, 1525.
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kopowicz, P. Tetrahedron 1998, 54, 6051.
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Chen, W.; Schoen, F. J.; Levy, R. J. Circulation 1994, 90, 323.
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21. Constantinou-Kokotou, V.; Magrioti, V.; Markidis, T.;
Kokotos, G. J. Peptide Res. 2001, 58, 325.
Conclusion
22. Magrioti, V.; Constantinou-Kokotou, V. Lipids 2002, 37, 223.
23. For example: Compound 4: [a]D=+4.0 (c 1.0, CHCl3),
1H NMR (200 MHz, CDCl3) d=7.25–7.40 (5H, m, Ph), 5.30–
5.60 (2H, m, CHCH, Z isomer), 4.82 (1H, b, NH), 4.50–4.65
(3H, m, CH, CH2Ph), 3.47 (2H, m, CH2CH), 2.00–2.15 (2H,
m, CH2CH), 1.45 [9H, s, C(CH3)3], 1.20–1.40 (20H, m,
10ÂCH2), 0.89(3H, t, J=6.8 Hz, CH3), 13C NMR (50 MHz,
CDCl3) d=155.2 (CO), 138.0 (aromatic C), 133.4 (CH),
127.5–128.4 (aromatic CH and CH), 79.2 (C), 73.1 (CH2), 72.7
(CH2), 48.0 (CH), 31.9(CH 2), 29.6 (2ÂCH2), 29.3 (CH3), 28.4
(3ÂCH2), 28.3 (3ÂCH2), 27.8 (CH2), 22.7 (CH2), 14.1 (CH3).
Compound 6: [a]D=À4.5 (c 0.5, CH3OH), 1H NMR
(200 MHz, CD3OD) d=3.75 (1H, dd, CHHOH, J1=3.2 Hz,
J2=12.0 Hz), 3.53 (1H, dd, CHHOH, J1=7.0 Hz, J2=12.0
Hz), 3.17 (1H, m, CH), 1.60 (2H, m, CH2CHCH2OH), 1.15–
1.50 (24H, m, 12ÂCH2), 0.90 (3H, t, J=7.0 Hz, CH3), 13C
NMR (50 MHz, CD3OD) d=62.1 (CH2OH), 54.7 (CH), 33.1
(CH2), 30.8 (2ÂCH2), 30.6 (4ÂCH2), 30.5 (4ÂCH2), 26.5
(CH2), 23.7 (CH2), 14.4 (CH3). Compound 9: [a]D=+3.6 (c
1.0, CH3OH), 1H NMR (200 MHz, CD3OD) d=3.25–3.80
(7H, m, 2ÂCH2O, CH2OH, CH), 1.58 (2H, m, CH2CH2O),
An efficient method for the synthesis of enantiopure
long chain 2-amino-alcohols starting from serine was
developed. The length of the side chain depends on the
alkyl-triphenylphosphonium bromide used for the
olefination reaction or the alkyl bromide used for the
etherification. 2-Amino-hexadecanol, the corresponding
ether derivative and 2-amino-oleyl alcohol exhibit
interesting in vivo anti-inflammatory and analgesic
activity and constitute a class of ‘lead’ compounds for
the development of novel pharmaceutical agents.
Acknowledgements
V.M. is indebted to the Greek National Scholarship
Foundation for financial support.
1.15–1.45 (18H, m, 9ÂCH2), 0.87 (3H, t, J=6.8 Hz, CH3), 13
C
References and Notes
NMR (50 MHz, CD3OD) d=72.8 (CH2O), 68.7 (CH2O), 60.3
(CH2OH), 54.3 (CH), 33.1 (CH2), 30.8 (2ÂCH2), 30.6
(3ÂCH2), 30.5 (3ÂCH2), 27.1 (CH2), 23.8 (CH2), 14.4 (CH3).
Compound 12: [a]D=+9.2 (c 1.0, CHCl3), MS (FAB) m/z
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1
(%): 284 (M++H, 100), 252 (MÀ59, 10), 55 (52), H NMR
(200 MHz, CDCl3) d=6.43 (4H, m, NH+3 , OH), 5.33 (2H, m,
CH=CH), 3.62–4.00 (2H, m, CH2OH), 3.41 (2H, m, CH,
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J=7.0 Hz, CH3), 13C NMR (50 MHz, CDCl3) d=129.5 and
130.0 (CHCH), 62.0 (CH2OH), 53.8 (CH), 31.9(2 ÂCH2), 29.7
(CH2), 29.5 (2ÂCH2), 29.4 (2ÂCH2), 29.3 (CH2), 29.1 (CH2),
27.2 (CH2), 27.1 (CH2), 25.6 (CH2), 22.6 (CH2), 14.1 (CH3).
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