Synthesis and hypolipidemic activity of N-phthalimidomethyl tetra-O-acyl-α-D-mannopyranosides

Article abstract of DOI:10.1016/S0008-6215(01)00088-X

A facile synthesis of anomerically pure phthalimidomethyl 2,3,4,6-tetra-O-acetyl- and phthalimidomethyl 2,3-di-O-acetyl-4,6-di-O-benzoyl-α-D-mannopyranosides (6 and 9b) starting from N-hydroxymethylphthalimide and tri-O-acetyl-D-glucal is described. Compounds 3, 6, 8, 9a and 9b have been tested for their hypolipidemic activity in mice. All these compound showed significant reduction of plasma cholesterol and triglyceride levels. Compound 9b has been found to possess the highest activity.

Full text of DOI:10.1016/S0008-6215(01)00088-X

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Carbohydrate Research 332 (2001) 335–340
Note
Synthesis and hypolipidemic activity of
N-phthalimidomethyl tetra-O-acyl-a-
D-
mannopyranosides
Rajendra M. Srivastava,a,* Fernando J.S. Oliveira,a Ladjane P. da Silva,a
Joa˜o R. de Freitas Filho,a Shalom P. Oliveira,b Vera L.M. Limab
aDepartamento de Qu´ımica Fundamental, Uni6ersidade Federal de Pernambuco, Cidade Uni6ersita´ria,
50.740-540 Recife, PE, Brazil
bDepartamento de Bioqu´ımica, Uni6ersidade Federal de Pernambuco, Cidade Uni6ersita´ria, 50.670-420 Recife,
PE, Brazil
Received 10 October 2000; received in revised form 10 March 2001; accepted 22 March 2001
Abstract
A facile synthesis of anomerically pure phthalimidomethyl 2,3,4,6-tetra-O-acetyl- and phthalimidomethyl 2,3-di-O-
acetyl-4,6-di-O-benzoyl-a- -mannopyranosides (6 and 9b) starting from N-hydroxymethylphthalimide and tri-O-ace-
tyl- -glucal is described. Compounds 3, 6, 8, 9a and 9b have been tested for their hypolipidemic activity in mice. All
D
D
these compound showed significant reduction of plasma cholesterol and triglyceride levels. Compound 9b has been
found to possess the highest activity. © 2001 Elsevier Science Ltd. All rights reserved.
Keywords: a-D-Mannopyranoside; N-Hydroxymethylphthalimide; Tri-O-acetyl-D-glucal
Phthalimide derivatives are known to dis-
reported. The literature does not record a
phthalimidoylalkyl moiety as an aglycone in
mannopyranoside derivative. If such glycoside
is prepared, the carbohydrate moiety might
play an important role as a carrier of this
group to an appropriate site suited for the
pharmacological activity. With this objective
in mind, the synthesis of phthalimidoylmethyl
mannopyranoside was planned and, indeed,
compounds 3, 6, 8, 9a and 9b exhibited signifi-
cant hypolipidemic activity. The results are
described below.
play
antitumor,1
anticonvulsant,2
and
hypolipidemic3,4 activities. Our own group has
been interested in N-substituted phthalimides
and found that N-[3-phenyl-1,2,4-oxadiazol-5-
yl]methylphthalimide
possesses enhanced
analgesic activity.5 A recent report describes
the synthesis of methyl 2,6-anhydro-3-deoxy-
3-phthalimido-a- -mannopyranoside and its
D
15N-labeled analog, for which the spectro-
scopic and stereochemical studies were carried
out,6 but no biological activity tests have been
The synthesis of N-phthalimidomethyl 4,6-
di-O-acetyl-2,3-dideoxy-a- -erythro-hex-2-
D
* Corresponding author. Tel.: +55-81-27184443; fax: +
55-81-2718442.
E-mail address: rms@npd.ufpe.br (R.M. Srivastava).
enopyranoside (3) was achieved in high yield
by the reaction of N-hydroxymethylphthal-
0008-6215/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(01)00088-X

336
R.M. Sri6asta6a et al. / Carbohydrate Research 332 (2001) 335–340
lished, we proceeded to treat it with potassium
permanganate. The reaction furnished pre-
sumably a diol 5, but it was difficult to estab-
lish the configuration of the hydroxyl groups
imide (1) with 3,4,6-tri-O-acetyl-1,2-dideoxy-
-arabino-hex-1-enopyranose (tri-O-acetyl-
D
D
-
glucal) (2) using Ferrier’s method7 (Scheme 1).
Although, it is known7 that the unsaturated
sugars formed by Ferrier’s method contain
more than 90% of a anomer, in the present
work, only one product was isolated. In order
to confirm the anomeric configuration of 3, we
hydrogenated it. The product 4 gave an
anomeric proton at l 5.07 ppm as a broad
singlet (W/2:4.08 Hz) indicating the axial
configuration of the phthalimidomethyloxy
group. Hence, it is concluded that compound
3 is exclusively the a anomer. Once the
anomeric configuration of 3 has been estab-
1
at C-2 and C-3 by H NMR. We acetylated 5
and got the tetra-O-acetyl derivative 6. The
1H NMR spectrum of this compound showed
four signals between l 2.07 and 2.13 ppm due
1
to acetyl groups. However, the H NMR spec-
trum turned out to be more complicated be-
cause H-2, H-3, H-4 and ꢀNꢀCH2ꢀOꢀ protons
appeared between l 5.20 and 5.40 ppm. All
attempts to determine the configurations at
C-2 and C-3 by NMR spectroscopy failed.
Even the shift reagent did not help to
Scheme 1.

R.M. Sri6asta6a et al. / Carbohydrate Research 332 (2001) 335–340
337
Table 1
H-4 as a triplet (J 10.1 Hz) and H-3 as a
doublet of doublets (J 10.2 and 3.3 Hz). With
this information, it is obvious that 3 is a
mannopyranoside with the aglycone portion
oriented axially at C-1.
Effect of compounds 3, 6, 8, 9a and 9b on mice plasma
cholesterol and triglyceride levels of mice a
Com- Cholesterol (mmol/L)
pound
Triglycerides (mmol/L)
Compounds 3, 6, 8, 9a,b have been tested
for their hypolipidemic activity. Phthalimi-
domethyl 4,6-di-O-acetyl-2,3-dideoxy-a- -ery-
Before
After
Before
After
D
3 b
3.4390.29 2.7190.37 e 1.9490.23 1.4490.24 d
2.9890.26 2.4290.22 f 1.6590.08 1.3590.08 e
3.0790.34 2.5490.26 f 1.6390.15 1.2890.12 f
3.4090.46 2.9190.51 e 1.9290.18 1.4890.13 d
3.4390.26 2.9390.28 d 1.8390.25 1.3390.20 e
2.6890.16 2.6690.17 1.0990.04 1.0990.04
6 b
thro-hex-2-enopyranoside (3) reduced the total
plasma cholesterol and triglycerides levels by
21 and 25% in normolipidemic Swiss white
male mice (Table 1) after 16 days of treatment
with 20 mg/kg per day. A smaller reduction
was found when the animals were treated with
8 c
9a c
9b c
1%
CMC
phthalimidomethyl 2,3,4,6-tetra-O-acetyl-a- -
D
a Number of mice for each test group=6. Results are
shown as the mean9S.D.
mannopyranoside (6), where the cholesterol
and triglycerides levels decreased by 17–18%.
An improvement in hypotriglyceridemic activ-
ity in vivo, but not in the hypocholesterolemic
activity, was observed in compounds 8, 9a and
9b, respectively. As shown in Table 1, the
animals treated with phthalimidoylmethyl 4,6-
b Results for treatment with 20 mg/kg per day.
c Results for treatment with 10 mg/kg per day.
d PB0.01.
e PB0.001.
f PB0.0001.
di-O-benzoyl-2,3-dideoxy-a- -erythro-hex-2-
D
separate the peaks sufficiently for configura-
tional analysis. Frustrated with the tetra-O-
acetyl compound 6, we turned our attention to
the 4,6-di-O-benzoyl derivative with the hope
to get separation of the H-2, H-3 and H-4
protons for determining their correct configu-
rations. To achieve this goal, compound 3 was
hydrolyzed to 7 using a mixture of triethy-
lamine, methanol and water. Benzoylation of
7 and usual work-up afforded a crystalline
compound 8 which showed a single spot on
enopyranoside
(8),
phthalimidoylmethyl
-mannopyranoside (9a)
4,6-di-O-benzoyl-a-
D
and phthalimidoylmethyl 2,3-di-O-acetyl-4,6-
di-O-benzoyl-a- -mannopyranoside (9b), at
D
10/mg/kg per day, exhibited significant reduc-
tion of the plasma triglyceride concentrations
(21, 23 and 27%, respectively). Therefore, al-
though all compounds showed strong hy-
polipidemic activity for reducing triglycerides,
compound 9b has been found to possess the
highest activity. Finally, it was found that
administration of 1% carboxymethyl cellulose
(CMC) to the animals had no significant
changes in mice plasma cholesterol and
triglycerides (2%).
In conclusion, the results show that these
drugs are able to reduce the plasma lipid levels
in normolipidemic mice and that they offer
excellent promise as new hypolipidemic
agents.
1
TLC (Rf 0.70). The 300 MHz H NMR spec-
trum of this derivative showed a broad signal
for H-1 at l 5.38 ppm with a narrow splitting
at the top of the peak. It was therefore not
possible to determine the anomeric configura-
tion with certainty. However, the COSY (1H–
1H) spectrum clearly showed that H-1 is
coupled with H-2 at l 5.88 and H-4 at l 5.72.
The latter coupling between H-1 and H-4 can
only take place if H-1 and H-4 are on the
same side, i.e., the anomeric proton at C-1 is
oriented equatorially and H-4 is oriented ax-
ially. cis-Hydroylation of 8 gave 9a, which
was acetylated. The structure of the resulting
di-O-acetyl derivative 9b was deduced from its
1H NMR spectrum. The anomeric proton ap-
peared as a doublet (J 2.1 Hz), H-2 as a
doublet of doublets at 5.28 (J 1.8 and 3.3 Hz),
1. Experimental
General methods.—Melting points were de-
termined on an Electrothermal digital melting
point apparatus (model 9100) and are uncor-
rected. Infrared spectra were measured with a

338
R.M. Sri6asta6a et al. / Carbohydrate Research 332 (2001) 335–340
mL) was hydrogenated at rt in the presence of
5% palladium on charcoal (15 mg) for 4 h at
101 KPa. Removal of the catalyst by filtration
left a clear solution which showed one spot on
TLC with Rf 0.50; the Rf of the starting
material in this system was 0.39. Solvent evap-
oration left a solid which weighed 75 mg
(74.6%). Crystallization and recrystallization
of 4 from EtOH gave crystals with mp 97.2–
97.7 °C; [h]2D5 +79.9°90.4 (c 2.0, CHCl3); Rf
0.50; IR (KBr): 3052 (CꢀH, Ar), 2984 (wCH3),
2925 (was-CH2ꢀ), 2993 (ws-CH2ꢀ), 1778 (was, CO
of phthalimide function), 1733 (ws, CO of ph-
thalimide and acetyl groups), 1615 (wCꢁC,
Bruker model IFS66 FT-IR spectrophotomer
using potassium bromide discs. NMR spectra
were recorded with a Varian Unity Plus 300
MHz instrument using CDCl3 as solvent, un-
less otherwise stated, and Me4Si as internal
standard. The specific rotation of compound 8
was obtained on a Perkin–Elmer, model 241
polarimeter and the sp rotations of other com-
pounds were measured on JASCO, model
DIP-370 polarimeter. Silica gel coated plates
with fluorescent indicator (PF254) were used
for thin-layer chromatography (TLC) and the
spots were revealed under ultraviolet light.
The solvent system for running the TLC
plates was a mixture of 1:9 EtOAc–CH2Cl2.
1
Ar). H NMR (CDCl3): l 1.68–1.88 (m, 4 H,
2CH2), 1.96 (s, 3 H, CH3COꢀ), 2.00 (s, 3 H,
CH3COꢀ), 3.92–4.1 (m, 2 H, H-6, H-6%), 4.20
(m, 1 H, H-5), 4.60 (m, 1 H, H-4), 5.07 (bs, 1
H, H-1), 5.12 and 5.22 (2d, 2 H, J 10.20 Hz,
NꢀCH2ꢀOꢀ), 7.72 (dd, 2 H, J 5.7, J 3.3 Hz,
H-5% and H-6%), 7.85 (dd, 2 H, J 5.7, J 3.3 Hz,
H-4% and H-7%). Anal. Calcd For C19H21NO8
(391.36): C, 58.31; H, 5.37; N, 3.58. Found: C,
58.01; H, 5.25; N, 3.45.
Phthalimidomethyl
dideoxy - h -
(3).—N-(Hydroxymethyl)phthalimide
(0.23 g, 1.30 mmol), and tri-O-acetyl-
4,6-di-O-acetyl-2,3-
D
- erythro - hex - 2 - enopyranoside
(1)
D
-glucal
(2) (0.33 g, 1.21 mmol) in dry benzene (40
mL), were stirred in a 150 mL round-bottom
flask under nitrogen atmosphere. Borontri-
fluoride etherate (0.5 mL) was added to it and
the stirring continued for 75 min at rt. Thin-
layer chromatography showed a fast moving
spot of Rf 0.62 (alcohol 1 had Rf 0.34). Neu-
tralization of this solution with solid
NaHCO3, drying with anhyd Na2SO4 followed
by solvent evaporation left a crystalline solid
which, after chromatography over silica gel,
provided crystals (0.36 g, 76.3% based on 2),
which after recrystallization from EtOH
melted at 120–120.8 °C; [h]2D5 +46°92 (c 0.9,
CHCl3); Rf 0.62; IR (KBr): 3055 (CꢀH, ar),
2938 (CꢀH, aliph.), 1760 (was CO, of phthal-
imide part) and 1726 (ws CO of phthalimide
group and CO of acetyl groups), 1609 cm−1
Phthalimidomethyl
4,6-di-O-acetyl-h- -
D
mannopyranoside (5).—Compound 3 (0.30 g,
0.77 mmol) in THF (18 mL) was treated with
a solution of KMnO4 (0.14 g, 0.89 mmol in 10
mL of water) and the contents were stirred at
rt for 5 h. TLC showed the disappearance of
the starting material and appearance of a new
product with Rf 0.30. Filtration over celite
followed by solvent removal under reduced
pressure gave a crude product which was
chromatographed over a column containing
silica gel. Pure 5 was eluted from 4:1 CHCl3–
EtOAc. Fractions containing 5 were com-
bined, and the solvent evaporated to give
0.235 g of chromatographically pure product
which, after crystallization from EtOH,
yielded 0.21 g (64.4%) of pure 5, mp 115.2–
115.5 °C; [h]2D5 +26°92 (c 0.7, CHCl3); Rf
0.30; IR (KBr): 3100–3661 (broad, OH), 1781
(was-CONꢀ), 1725 (wsCO of phthalimide group
and wCO of acetyl groups), 1611 cm−1(w-
CꢁCꢀ, ar). 1H NMR (CDCl3): l 2.07–2.13 (2s,
6 H, 2CH3COꢀ), 2.9–3.5 (b, 2 H, OH), 3.80–
4.10 (m, 4 H, H-2, H-3, H-6, H-6%), 4.20–4.36
(m, 1 H, H-5), 5.01–5.18 (dd, 1 H, J 10.2, J
9.6 Hz, H-4,), 5.2 (bs, 1 H, H-1), 5.26 and 5.29
(2d, 2 H, J 10.20 Hz, ꢀNꢀCH2ꢀOꢀ) 7.80 (m, 2
H, J 5.40, J 3.0 Hz, H-5% and H-6%), 7.94 (m,
2 H, J 5.40, J 3.0 Hz, H-4% and H-7%).
1
(CꢁC, ar). H NMR (CDCl3): l 2.08 (s, 3 H,
CH3COꢀ), 2.09 (s, 3 H, CH3COꢀ), 4.10–4.26
(m, 3 H, H-5, H-6, H-6%), 5.27 and 5.35 (2d, 2
H, J 10.20 Hz, ꢀNꢀCH2ꢀOꢀ), 5.38 (m, 2 H,
H-1 and H-4), 5.80 (ddd, J2,3 10.20, J1,2 2.70,
J2,4 1.5 Hz, H-2), 5.90 (d, J3,2 10.2 Hz, H-3),
7.78 (dd, 2 H, J 5.40, J 3.0 Hz, AA% BB%
system, H-5% and H-6%), 7.92 (dd, 2 H, J 5.40,
J 3.00 Hz, AA%BB% system, H-4% and H-7%).
Anal. Calcd for C19H19NO8 (389.34): C, 58.61;
H, 4.92; N, 3.60. Found. C, 58.34; H, 4.68; N,
3.58.
Phthalimidomethyl
dideoxy-h- -erythro-hexopyranoside
Compound 3 (0.1g, 0.26 mmol) in EtOAc (5.0
4,6-di-O-acetyl-2,3-
D
(4).—

R.M. Sri6asta6a et al. / Carbohydrate Research 332 (2001) 335–340
339
Phthalimidomethyl
dideoxy - h -
4,6-di-O-benzoyl-2,3-
Phthalimidomethyl 2,3,4,6-tetra-O-acetyl-h-
-mannopyranoside (6).—Compound 5 (0.14
D
- erythro - hex - 2 - enopyranoside
D
(8).—To compound 7 (2.15 g, 7.04 mmol) in
dry pyridine (3.0 mL) at 0 °C and under N2
atmosphere was added BzCl (2.47 g, 2.04 mL,
17.6 mmol). The contents were maintained at
this temperature for 3 h under stirring. At this
point, completion of the reaction was checked
by TCL (Rf 0.7; starting compound 7 had Rf
0.05). Neutralization of the contents with
NaHCO3 and extraction with CH2Cl2, drying
(NaSO4) and solvent evaporation afforded
2.53 g of the crude product. Liquid chro-
matography over silica gel using 4:1 hexane–
EtOAc gave 2.42g (66.9%) of chromato-
graphically pure 8. Crystallization and recrys-
tallization from EtOH furnished crystals, mp
125.7–126.4 °C; [h]2D0 +91.65° (c 2, CHCl3);
Rf 0.7; IR (KBr): 3033 (wCꢁC, ar), 3070
(wCꢁC, ar), 1785 (wasCO of phthalimide
group), 1723 (ws CO of phthalimide part and
g, 0.33 mmol) was dissolved in dry pyridine
(2.0 mL), cooled to 0 °C under N2 atmosphere
followed by the addition of Ac2O (1.39 g, 1.5
mL, 13.6 mmol). The contents were left under
stirring overnight at rt. Solvent evaporation
left a viscous mass with Rf 0.5. Liquid chro-
matography over silica gel using 1:9 hexane–
CHCl3 provided 0.135 g (80.4%) of pure 6;
[h]2D5 +31°91 (c 1.2, CHCl3); Rf 0.5; IR
(KBr): 2961 (wCꢀH), 1778 (wasCO of phthal-
imide group), 1752 (wsCO of phthalimide
groups), 1726 (wCO of acetyl groups), 1610
1
cm−1 (w-CꢁCꢀ, ar). H MNR (CDCl3): l 1.97
(s, 3 H, CH3COꢀ), 2.03 (s, 3 H, CH3COꢀ),
2.06 (s, 3 H, CH3COꢀ), 2.16 (s, 3 H,
CH3COꢀ), 4.00 (dd, 1 H, J 12.30, J 2.10, H-6
or H-6%), 4.12 (m, 1 H, H-5), 4.27 (dd, 1 H, J
12.30, J 4.50 Hz, H-6 or H-6%), 5.15 (d, 1 H, J
2.10 Hz, H-1), 5.22–5.40 (m, 5 H, H-2, H-3,
H-4 and ꢀNꢀCH2ꢀOꢀ), 7.81 (dd, 2 H, J 5.70,
J 3.30 Hz AA%BB%, H-5% and H-6%), 7.94 (dd, 2
H, J 5.7, J 3.20 Hz, AA%BB%, H-4% and H-7%).
Anal. Calcd. for C23H25NO12 (507.43): C,
54.43; H, 4.93; N, 2.76. Found: C, 54.32;
H,5.16; N, 2.59.
1
wCO of benzoyl groups), 1600 (wCꢁC, ar). H
NMR (CDCl3): l 3.8–4.58 (m, 3 H, H-5, H-6,
and H-6%), 5.31 and 5.39 (2d, 2 H, J 10.2 Hz,
OꢀCH2ꢀN), 5.44 (nm, 1 H, H-1), 5.72 (d, 1 H,
J 7.8 Hz, H-4), 5.87 (dt, 1 H, J 10.5, J 2.7, J
2.1 Hz, H-2), 6.05 (d, 1 H, J 10.5 Hz, H-3),
7.39 (t, 2 H, J 7.5 Hz, meta protons of one
benzoyl group), 7.42 (t, 2 H, J 7.5 Hz, meta
protons of the other benzoyl group), 7.49–
7.60 (m, 2 H, para protons of the benzoyl
groups), 7.76 (dd, 2 H, J 5.55, J 3.30 Hz, H-5%,
H-6%), 7.90 (dd, 2 H, J 5.40, J 3.00 Hz, H-4%
and H-7%), 8.0 (dd, 2 H, J 8.40, J 1.65 Hz,
ortho protons of one benzoyl group), 8.04
(dd, 2 H, J 8.40, J 1.20 Hz, ortho protons of
other benzoyl group). Anal. Calcd for
C29H23NO8 (513.47): C, 67.83; H, 4.51; N,
2.73. Found: C, 67.81; H, 4.54; N, 2.90.
Phthalimidomethyl 2,3-dideoxy-h- -erythro-
D
hex-2-enopyranoside (7).—Compound 3 (2.75
g, 7.06 mmol) was dissolved in a 9:6:1 mixture
of MeOH (27.0 mL), water (18.0 mL) and
Et3N (3.0 mL) and stirred at rt for 5 h. TLC
plate revealed the disappearance of the start-
ing material and appearance of a new spot (Rf
0.05). Solvent evaporation left 2.42 g of crude
7 which, after column chromatography over
silica gel provided 1.84 g (86%) of pure 7 as a
semi-solid mass; IR (KBr): 3311 (b, wOH),
2944 (wCH2), 2914 (wCH), 1779 (wasCO of
phthalimide group), 1734 (wsCO of phthal-
imide group), 1610 cm−1 (wCꢁC, ar). 1H
NMR (CDCl3): l 1.4–2.4 (b, 2 H, OH), 3.70–
3.81 (m, 3 H, H-5, H-6, H-6%), 4.20 (dd, J 9.0
Hz, 1.8 Hz, H-4), 5.27 (narrow multiplet, 1 H,
J 2.1 Hz, H-1), 5.31 (s, 2 H, NꢀCH2ꢀO), 5.72
(ddd, 1 H, J 10.5, J 2.7, J 2.1 Hz, H-2), 5.98
(dt, 1 H, J 10.5, J 1.2 Hz, H-3), 7.78 (dd, 2 H,
J 5.4, J 3.0 Hz, H-5% and H-6%), 7.92 (dd, 2 H,
J 5.7, J 3.0 Hz, H-4%, and H-7%). Anal. Calcd
for C15H15NO6 (305.28): C, 59.01; H, 4.95; N,
4.58. Found: C, 59.48; H, 5.69, N, 4.26.
Phthalimidomethyl
4,6-di-O-benzoyl-h- -
D
mannopyranoside (9a).—To a stirred solution
of 8 (0.20 g, 0.039 mmol) in THF (6.0 mL)
was added KMnO4 (0.07 g, 0.44 mmol) drop-
wise in few minutes and the contents were left
for 5 h at rt. TLC showed the formation of a
new product with a Rf value of 0.17. Removal
of MnO2 by filtration followed by solvent
evaporation furnished a semi-solid material,
which after chromatography over a short
column using 1:1.5 hexane–EtOAc gave 0.13
(61%) of pure 9a; [h]2D3 +52°93 (c 0.7,
CHCl3); Rf 0.17; IR (KBr): 3494 (b, wOH),

340
R.M. Sri6asta6a et al. / Carbohydrate Research 332 (2001) 335–340
PAP method, an enzymatic assay9 for photo-
metric determination, using the enzymes
cholesterol esterase, cholesterol oxidase and
peroxidase contained in E. Merck test
1.14830.0001 Ecoline 25 reagents (Diagnos-
tica–E. Merck KGaA, Darmstadt, Germany),
according to the manufacturer’s instructions.
2953 (CH, aliph.), 1779 (wasCO of phthalimide
group), 1723 (wsCO of phthalimide and ben-
zoyl groups), 1602 (wCꢁC, ar). Anal. Calcd for
C29H25NO10 (547.51): C, 63.61; H, 4.60; N,
2.56. Found: C, 63.82; H, 4.77; N, 2.38.
Phthalimidomethyl 2,3-di-O-acetyl-4,6-di-
O-benzoyl-h-
D
-mannopyranoside
(9b).—To
Plasma
triglycerides
(E.
Merck
test
the dihydroxy compound 9a (0.095 g, 0.17
mmol) in dry pyridine (2.0 mL), in a 10 mL
round-bottom flask and cooled to 0 °C. Ac2O
(1.0 mL) was added. Stirring at rt overnight
gave the di-O-acetyl derivative (TLC, Rf 0.65).
Purification was achieved by column chro-
matography over silica gel. Elution with 1:9
EtOAc–hexane gave pure 9b (0.10 g, 91%);
[h]2D5 +35°92 (c 1.0, CHCl3); Rf 0.65; IR
(KBr): 1781.2 (wasCO of phthalimide group),
1753.2 (wsCO of phthalimide part), 1726.1
(wCO of acetyl and benzoyl groups) and
1.19706.0001 System Multi-Test) were also
measured enzymatically (GPO-PAP method)10
by a combination of the reactions catalyzed
by lipase, glycerokinase, glycerol phosphate
oxidase and peroxidase.
Statistics. All groups had ten animals and
each determination was processed before and
after the drug treatment. The results are ex-
pressed as mean9S.D. and we used paired
Student-‘t’ test. In all cases, PB0.05 was used
as the criterion of statistic significance.
1
1602.7 cm−1 (CꢁC, Ar); H NMR (CDCl3): l
1.87 (s, 3 H, CH3ꢀCO), 2.15 (s, 3 H,
CH3ꢀCO), 4.32–4.52 (m, 3 H, H-5, H-6, H-
6%), 5.21 (d, 1 H, J 2.10 Hz, H-1), 5.28 and
5.37 (2d, 2 H, J 10.2 Hz, OꢀCH2ꢀN), 5.28 (dd,
1 H, J 3.3, J 1.8 Hz, H-2), 5.56 (dd, 1 H, J
10.20, J 3.30 Hz, H-3), 5.73 (t, 1 H, J 10.1 Hz,
H-4), 7.34–7.46 (m, 4 H, meta protons of
benzoyl group), 7.49–7.60 (m, 2 H, para pro-
tons of benzoyl group), 7.79 (dd, 2 H, J 5.4, J
3.0 Hz, H-5%, H-6%), 7.93 (dd, 2 H, J 5.4, J 3.0
Hz, H-4%, H-7%), 8.01 (m, 4 H, ortho protons
of benzoyl group). Anal. Calcd for
C33H29NO12 (631.56): C, 62.75; H, 4.63; N,
2.21. Found: C, 62.71; H, 4.91; N, 2.23.
Hypolipidemic acti6ity tests
Drug administration. The compounds were
suspended in 1% carboxymethylcellulose and
administered orally in the morning8 at either
10 or 20 mg/kg per day for 2 week periods to
normolipidaemic male Swiss White mice (age
about 3 months, body weight 30–32 g) by
using an intubation needle. Periodic animal
body weights were obtained during the experi-
ment and expressed as a percentage of the
animal’s weight on day 0.
Acknowledgements
The authors express their gratitude to the
Brazilian National Research Council (CNPq)
and to Pernambuco State Foundation for Sci-
ence and Technology (FACEPE) for financial
help. The specific rotation of compound 8 was
determined in the Chemistry Department,
Federal University of Sa˜o Carlos, while the sp
rotations of other compounds were obtained
by Professor Joel Jones Jr., Institute of Chem-
istry, Federal University of Rio de Janeiro, for
which we are thankful.
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