Flexible synthesis and biological evaluation of novel 5-deoxyadenophorine analogues

Article abstract of DOI:10.1016/j.bmcl.2006.03.035

Adenophorine and its 5-deoxy analogue have been identified as natural iminosugars with efficient glycosidase inhibitory effects. The syntheses and biological evaluation of two new series of 5-deoxyadenophorine analogues in their racemic form are reported.

Full text of DOI:10.1016/j.bmcl.2006.03.035

Bioorganic & Medicinal Chemistry Letters 16 (2006) 3262–3267
Flexible synthesis and biological evaluation
of novel 5-deoxyadenophorine analogues
a
b
c
b
Morwenna S. M. Pearson, Rim Ouled Saad, Thierry Dintinger, Hassen Amri,
a,
a,
*
*
Monique Math e´ -Allainmat and Jacques Lebreton
a
Universit e´ de Nantes, CNRS, Laboratoire de Synth e` se Organique, UMR 6513, Facult e´ des Sciences et des Techniques,
rue de la Houssini e` re, BP 92208, 44322 Nantes Cedex 3, France
Laboratoire de Chimie Organique et Organom e´ tallique, Facult e´ des Sciences, Campus Universitaire-2092-El manar-Tunisie
2
b
c
Universit e´ de Nantes, CNRS, U3B, UMR 6204, Facult e´ des Sciences et des Techniques,
rue de la Houssini e` re, BP 92208, 44322 Nantes Cedex 3, France
2
Received 30 January 2006; revised 13 March 2006; accepted 13 March 2006
Available online 5 April 2006
Abstract—Adenophorine and its 5-deoxy analogue have been identified as natural iminosugars with efficient glycosidase inhibitory
effects. The syntheses and biological evaluation of two new series of 5-deoxyadenophorine analogues in their racemic form are
reported. The compounds 12e and 13d bearing a C11 and C alkyl chain, respectively, were found to be potent inhibitors of the
7
b-glucosidase from almond with K near to 60 lM. The compounds 13a,d which possess a 3,4-cis stereochemistry were efficient
i
on glucosidases but also on the b-galactosidase, what was not observed with the 3,4-trans series 12.
Ó 2006 Elsevier Ltd. All rights reserved.
Iminosugars have been the subject of particular atten-
tion in recent years because they were found to be inhib-
Therefore, N-alkylation of iminosugars, such as DNJ 1
6
or its deoxy analogues fagomine 3 and isofagomine 4 ,
1
itors not only of glycosidases but also of a range of
2
crucial enzymes such as glycosyltransferases, glycogen
was proposed as a good approach to access novel inhib-
itors with enzyme specificity. The change in potency and
in enzyme selectivity of these lipophilic N-substituted
polyhydroxylated piperidine derivatives seemed to be
dependent not only on the nature of the N-alkyl side-
chain but also on the biologically active conformation
of the iminosugar. In the search for more potent and
more specific inhibitors targeting endoplasmic reticulum
(ER) a-glucosidase I implicated in several viral process-
es, including human immunodeficiency virus (HIV) and
3
4
phosphorylases, and metalloproteinases. Their struc-
tural resemblance to carbohydrates enabled them to be
designed as potential tools for the modulation of carbo-
hydrate-processing enzymes. Thus, digestive glycosi-
dases, participating in the regulation of carbohydrate
absorption in the small intestine and considered a seri-
ous target for type II diabetes treatment, were shown
to be inhibited by several natural or synthetic iminosu-
gars. As an example, 1-deoxynojirimycin 1 (DNJ—
7
hepatitis B virus, N-butyl-1-deoxynojirimycin 5 was
5
Fig. 1), first synthesized by Paulsen and Todt and later
shown to be a more effective viral agent than its parent
DNJ 1. A possible explanation for this difference
in potency was proposed by Asano et al., who showed
isolated from the roots of mulberry trees, was rapidly
characterized as a potent inhibitor of glucosidases
in vitro. Its low efficiency in vivo was solved by the
development of substituted analogues, leading to an
1
using H NMR studies that N-alkylation of DNJ 1
led to a conformational change (the C OH axial confor-
6
TM
N-hydroxyethyl-DNJ 2 called Miglitol and commer-
cialized today by Glaxo to treat type II diabetes.
mation) of the molecule and consequently enhanced the
8
specificity of inhibition of ER a-glucosidase I. Further-
more, N-butyl-DNJ 5 was also characterized as an
inhibitor of ceramide glycosyltransferase (CGT), an
enzyme involved in glycosphingolipid biosynthesis that
has been approved as a good candidate for the treatment
of Gaucher disease, a severe lysosomal storage disor-
Keywords:
inhibitors.
Iminosugars;
5-Deoxyadenophorine;
Glycosidase
9
*
Corresponding authors. Tel.: +33 2 51 12 54 02; e-mail: monique.
mathe@univ-nantes.fr; jacques.lebreton@univ-nantes.fr
der. Recently, Butters and co-workers found that
lengthening the N-alk(en)yl side-chain from C to C
4
18
0
960-894X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2006.03.035

M. S. M. Pearson et al. / Bioorg. Med. Chem. Lett. 16 (2006) 3262–3267
3263
OH
OH
N
OH
OH
HO
OH
OH
HO
HO
OH
OH
OH
OH
OH
OH
N
N
H
N
H
H
1
2
3
4
1-Deoxynojirimycin
Miglitol
Fagomine
Isofagomine
DNJ
OH
OH
OH
HO
OH
OH
HO
OH
OH
HO
OH
OH
N
N
R
N
4
H C
12
3
6
a: R= H3C
3
O
5
7
N-butyl-DNJ
6b: R= H3C
8
Figure 1. N-Alkylated iminosugars.
OH
OH
improved iminosugar retention in the cell and therefore
OH
1
0
OH
OH
OH
OH
enhanced the CGT inhibitory efficacy. As observed,
the lipophilic N-cis-13-octadecenyl-DNJ 6a did not
inhibit ER oligosaccharide-processing enzyme glycosi-
HO
H C
OH
H C
3
OH
3
N
N
H
3
N
H
a n=8
b n=7
n
1
1
dases in culture HL60 cells, probably due to the acces-
sibility of these enzymes located in the ER lumen in
comparison with the CGT known to be located at the
cytosolic side surface of the various Golgi subfrac-
8
8
10
9
OH
OH
1
2
tions. Similar observations were previously made by
Aerts and co-workers with compound N-[(5-adaman-
tane-1-yl-methoxy)pentyl]-DNJ 7, which is a nanomolar
inhibitor (IC : 1.7 nM) of non-lysosomal glucosylce-
R
OH
OH
OH
OH
H C
3
R
N
H
N
H
5
0
ramidase but acted on a-glucosidases at a concentration
1
3
not far from the micromolar (IC : 0.87 mM). Another
5
0
approach to favour CGT specificity was to modify one
carbon configuration on the N-butyl-DNJ 5 piperidine
skeleton, to afford the galactono analogue N-butyl-
DGJ, which lost activity towards glucosidases but not
Figure 2. C-Alkylated iminosugars.
analogues), they proposed a strategy starting from
tri-O-benzyl-D-glucal to access, in eight steps, a key
bicyclic aziridine intermediate 9 (Fig. 2). This bicyclic
compound reacted with various heteroatomic
nucleophiles (amine, thiol, carboxylate or phosphate) to
give the corresponding a-1-C-substituted fagomine
derivatives. However, introducing an a-1-C-alkyl chain
with organometallic nucleophiles via this aziridine
intermediate 9 failed to give the desired products. This
was achieved with moderate yield by treatment of the
relatively unstable a-1-C-iodomethyl derivative of
1
4
to CGT.
It is clear that both stereochemistry modification and
the introduction of lipophilic substituents by simple
N-alkyl(en)ation on iminosugars such as DNJ could be
interesting strategies to design more efficient enzyme
inhibitors.
Recently, Martin and co-workers have synthesized and
studied a range of DNJ derivatives bearing the lipophilic
alkyl chain not only on the nitrogen atom of the piperidine
ring but also on the 1-C position of the iminosugar. With
mono-alkylated compounds, the best activities were
obtained on a-glucosidase (isomaltase) with the 1-C–C9
derivative 8a (IC : 3.5 nM) (Fig. 2) compared to the
1
7
fagomine with nPr CuLi to give 10 (Fig. 2). It should
2
be pointed out that a-1-C-substituted analogues of DNJ
1 or fagomine 3, such as adenophorine 11 or 5-deoxya
denophorine (+)-12a (Fig. 2), have recently been isolated
1
8
from plants.
5
0
1
5
N–C analogue 6b (IC : 230 nM) (Fig. 1). Further-
9
The investigations of our group into new strategies to
access 1,6-disubstituted piperidines have led us recently
to publish the first total synthesis of 1-O-b-D-glucopyr-
anosyl-5-deoxyadenophorine and its aglycon congener
50
more, the N–C8 and 1-C–C8 dialkylated compound
recently prepared by the same group from chiral pool
L-sorbose was characterized as a glucosylceramide syn-
thase inhibitor (IC : 174 lM) and was expected to be a
1
9
(+)-12a. In the present work, we extend this original
and flexible synthesis to the production of a series of
5-deoxyadenophorine analogues (±)-12 and (±)-13
(Fig. 2) and to the evaluation of their activities towards
5
0
1
6
weaker inhibitor of glucosidase than DNJ. Extending
their work on iminosugars to a-1-C-substituted
dideoxynojirimycin derivatives (1-C-alkyl fagomine

3264
M. S. M. Pearson et al. / Bioorg. Med. Chem. Lett. 16 (2006) 3262–3267
selected glycosidases. For this preliminary screening, the
syntheses were carried out on racemic series.
ineffective with free amine due to chelations with ruthe-
2
3
nium. Nevertheless, these reactions could be carried
out in acidic media to form an ammonium derivative
without complexation ability. In these conditions, die-
thylenic aminoalcohol exposed to Grubbs’ catalyst gave
the desired compounds contaminated by residual ruthe-
nium species. In fact, amino alcohols act as ligands so to
avoid this problem we protected the amine and hydroxyl
functions as oxazolidinone. Thus, amino alcohols 16a–e
were treated with carbonyldiimidazole in the presence of
triethylamine to give the corresponding oxazolidinone
derivatives. These were subjected to RCM reaction in
the presence of second generation Grubbs’ catalyst 18 in
refluxing dichloromethane to afford the trans-compounds
19a–e in very good yields (72–88%) (Scheme 1).
a-1-C-Alkyl iminosugars 12b–e and 13a,d were prepared
from the common 1-C-alkyl tetrahydropyridine interme-
diate 19. Starting from commercial trans-cinnamalde-
hyde, a methylenation reaction was performed using
2
0
+ À
Corey reagent Me S I to give epoxide 14 in 95%
3
yield (Scheme 1). Amino alcohol 15 was then obtained
in 69% yield for the two steps by regioselective nucleo-
philic ring-opening of the epoxide 14 with sodium azide
and subsequent reduction of the azide intermediate with
2
1
triphenylphosphine in the presence of water. This
modest yield resulted from successive recrystallizations
of the amino alcohol 15, which was contaminated by
triphenylphosphine oxide. In parallel, we performed this
reduction with SnCl ÆH O but without better results
The trans-3,4 iminosugar series was obtained by func-
tionalization of the selected intermediates 19b–e in a
three-step process (Scheme 1). Epoxidation of the dou-
ble bound with m-CPBA proceeded with good dia-
stereoselectivity (85/15 dr) in favour of the desired
endo isomers 20b–e, as already noted in our previous
2
2
(
40% yield). At this stage, we introduced, in a one-pot
process, the allyl and alkyl side-chains by condensation
of the amino alcohol 15 with the selected aldehydes to
give the corresponding imines. These were then treated
with two equivalents of allylmagnesium bromide to fur-
nish, with good diastereoselectivities, the diethylenic
trans-amino alcohols 16a–e. The minor cis-isomers
1
9
work. Opening these epoxides with acetic acid allowed
regioselective access to the monoacetates 21b–e with
some diacetate derivatives 22b–e (80/20 ratio) provided
by esterification of 21 in the reaction conditions. The
mixture of 21 and 22 was directly treated with potassium
carbonate in methanol to give quantitatively the corre-
sponding diols and subsequent hydrolysis of the oxazo-
17a–e (around 10% yield) present with the trans-isomers
could be separated in the following steps. It should be
noted that the formation of the major trans-derivative
9,22
1
16a is in accord with previous work from our group.
It is well documented in the literature that RCM is
a
b-c
d
+
R
N
H
R
O
N
H
OH
O
H
H N
OH
2
OH
O
14
15
16a-e
17a-e
trans-
(
90/10)
cinnamaldehyde
e-f
h
g
R
N
R
N
O
O
O
O
1
9a-e
20b-e
OAc
OAc
OH
OH
OAc
OH
OH
i-j
a: R=C H5
2
+
b: R=C H7
3
R
N
R
N
R
N
H
c: R=C H9
4
O
O
d: R=C7H15
e: R=C11H23
O
O
2
1b-e
22b-e
1
2b-e
5
-Deoxyadenophorine analogues
steps from amino alcohol 15,
overall yields: 14% for 12b, 8.5% for 12c,
% for 12d and 15% for 12e
7
N
N
7
Cl
Cl
Ru
Ph
P(Cy)3
1
8
+
À
Scheme 1. Reagents and conditions: (a) Me
c) PPh , THF, rt, overnight then H O, 24 h, 73%; (d) RCHO, MgSO
h, 52–65%; (e) CDI, Et N, DCM, 18 h, 69–88%; (f) 18-[Ru] (5 mol %), DCM, reflux, 1 h, 72–88%; (g) m-CPBA, NaH
4–93%; (h) AcOH, 100 °C, 17 h; (i) K CO , MeOH, rt, 3 h, 50–70% for two steps; (j) 8 N aq NaOH, MeOH, 95 °C, 24 h, 66–74%.
3
S I , NaH, DMSO/THF, 0 °C, 30 min then rt, 40 min, 95%; (b) NaN
, THF, rt, 12 h, then allylmagnesium bromide, THF, Et
PO
, DCM, 0 °C to rt, 72 h,
3
, acetone/H
2
O, reflux, 2 h, 94%;
(
3
2
4
2
O, À78 °C to À10 °C,
6
5
3
2
4
2
3

M. S. M. Pearson et al. / Bioorg. Med. Chem. Lett. 16 (2006) 3262–3267
3265
2
4
lidinone with aqueous NaOH solution in methanol led
to the desired compounds 12b–e in 37–47% yield (three
steps) after flash chromatography purification.
The preliminary biological assays were investigated in
order to reveal the potency of these novel iminosugars
12 and 13 on a range of a- and b-glycosidases and to
study the influence of the length of the alkyl chain on
the inhibition of these selected enzymes. It must be not-
ed that every compound tested here is in a racemic mix-
ture. Nevertheless, the relative stereochemistry of these
analogues can be regarded as that corresponding to
5-deoxyadenophorine (Fig. 2) for compounds 12b–e
and its 4-epimer for compounds 13a,d.
The cis-3,4 iminosugar series was obtained starting from
the common precursors 19a,d in a four-step process
(
Scheme 2). Stereoselective dihydroxylation of ethylenic
compounds 19a,d under Upjohn conditions afforded a
mixture of cis-diastereoisomers 23a,d and 24a,d in a
7
0/30 ratio. At this point, the use of a bulky osmium
reagent like AD-mix-a increased the diastereoselectivity
80/20) in favour of compound 23. However, these cis-
(
With iminosugars 12b–e showing the 3,4-trans-diol
stereochemistry, evaluation on a- and b-glucosidases
or galactosidases and a-mannosidase revealed that only
the glucosidases were affected by these compounds
(Table 1). The inhibitory effects on b-glucosidase were
clearly observed with a 1 mM concentration of the pre-
sumed inhibitors 12 bearing the longest alkyl side-chain
C and C , compounds 12d and e, respectively. The
diols could be separated in their acetonide forms after
an additional protection step carried out with
2
,2-dimethoxypropane in dichloromethane. Pure com-
pounds 25a,d were isolated in around 70% yield. Subse-
quent cleavage of the acetal and carbamate protective
groups, in classical acidic and basic conditions, respec-
tively, led to the target molecules 13a,d in 43% overall
yield starting from tetrahydropyridine derivatives 19a,d.
7
11
activities were weaker on a-glucosidase while no activity
OH
OH
N
O
O
OH
OH
b
a
+
R
N
R
N
R
N
R
O
O
O
O
O
O
O
O
19a,d
23a,d
24a,d
25a,d
OH
OH
c, d
OH
R
N
H
a: R=C H
13a,d
2
5
d: R=C H
7
15
4
-epi-5-deoxyadenophorine analogues
steps from amino alcohol 15,
overall yields: 21% for 13a and 14% for
3d
7
1
2 2 2 2
Scheme 2. Reagents and conditions: (a) AD-mix-a, (DHQ) PHAL, MeSO NH , t-BuOH/H O, 0 °C to rt, 12 h; (b) DMP, APTS, DCM, rt, 3 h, 72%
for 25a and 65% for 25d in two steps; (c) 2 N aq HCl, THF, rt, 12 h; (d) 8 N aq NaOH, MeOH, 95 °C, 24 h, 60% for 13a and 67% for 13d in two steps.
Table 1. Inhibitory activities of (±)-5-deoxy analogues of adenophorine 12b–e and of some 4-epimers 13a,d
OH
OH
a: R=C H
2
5
OH
OH
OH
OH
b: R=C H
3
7
c: R=C H
4
9
d: R=C H
7
15
R
N
H
R
N
H
e: R=C11H23
(+/-)-12b-e
(
+/-)-13a,d
b
Enzyme/inhibitor
12b
12c
12d
12e
13a
13d
(+)-12a
a
c
a-Glucosidase/yeast
NI
NI
NI
NI
NI
NI
NI
196 lM
58 lM
NI
123 lM
NI
154 lM
61 lM
141 lM
NI
NI
NI
b-Glucosidase/almond
a-Galactosidase/green coffee
b-Galactosidase/Aspergillus
a-Mannosidase/almond
NI
NI
NI
NI
83%
NI
721 lM
NI
NI
6.4 lM
34 lM
—
d
NI
NI
NI
NI
NI
i
Percentage of inhibition at 1 mM concentration or K when measured, in optimal conditions.
a
NI, no inhibitory effect, less than 40% inhibition at 1 mM.
IC50 values of natural (+)-5-deoxyadenophorine (+)-12a, taken from Ref. 25.
a-Glucosidase from rice.
b
c
d
b-Galactosidase from bovine liver.

3266
M. S. M. Pearson et al. / Bioorg. Med. Chem. Lett. 16 (2006) 3262–3267
was noted on galactosidases and a-mannosidase. The Ki
was evaluated for compound 12e and was found to be
aldehyde and on the introduction of lipophilic and
exotic side-chains at the anomeric position of these
1-deoxyiminosugars.
1
96 lM on a-glucosidase and 58 lM on b-glucosidase
(
Table 1). For these 1-C-alkyl iminosugars in their a
anomeric form, it could be surprising to observe such
activity on b-glucosidase. However, Compain and
Co-workers recently published similar results for a-1-C-
alkyl-1-deoxynojirimycin derivatives and, with a-1-C-
octyl-1-deoxynojirimycin 8b (Fig. 2), they found
inhibition activities not far from 25 lM on a-glucosidase
Acknowledgments
This work was supported by the ‘Minist e` re de l’Educa-
tion Nationale de la Recherche et de la Technologie’
with a doctoral fellowship for Morwenna S. M. Pearson.
We also thank the CMCU (Cooperation inter-universi-
taire Franco-Tunisienne) for a grant (R. Ouled Saad).
We are grateful to our colleagues Dr. Val e´ rie Fargeas
and Dr. Corinne Andr e´ for helpful discussions.
1
5
(
yeast) and b-glucosidase (sweet almond). On the other
hand, Asano and co-workers stated that natural
-deoxyadenophorine (+)-12a had no inhibition effects
on a series of a-glucosidases and a b-glucosidase
5
2
5
(
almond) (Table 1). All these results could indicate
that the long a-1-C-alkyl chain of our iminosugar 12e
induces a complementary effect in the recognition of
these potential inhibitors, especially in the b-glucosidase
enzymatic site.
References and notes
1
. (a) Asano, N.; Nash, R. J.; Molyneux, R. J.; Fleet, G. W.
J. Tetrahedron: Asymmetry 2000, 11, 1645; (b) Asano, N.
Curr. Top. Med. Chem. 2003, 3, 471.
(
+)-5-Deoxyadenophorine (+)-12a was also found to
have a potent effect on a-galactosidase (IC : 6.4 lM,
2. Compain, P.; Martin, O. P. Curr. Top. Med. Chem. 2003,
3, 541.
3. Somsak, L.; Nagy, V.; Hadady, Z.; Docsa, T.; Gerhely, P.
Curr. Pharmacol. Des. 2003, 9, 1177.
5
0
Table 1) and b-galactosidase (IC : 34 lM, Table 1),
5
0
but this was not observed with compounds (±)-12b–e
in our experiments. Surprisingly, the 4-epi analogues
4
5
6
. Moriyama, H.; Tsukida, T.; Inouye, Y.; Nishimura, S.-I.
J. Med. Chem. 2004, 47, 1930.
. Paulsen, H.; Todt, K. Adv. Carbohydr. Chem. 1968, 23,
(
(
±)-13 revealed some activity on a-galactosidase
K = 721 and 141 lM for compounds 13a and d,
i
respectively) and
a
structure–activity relationship
1
15.
depending on the length of the alkyl chain seemed to
be observed. Compound 13d, bearing the C7 alkyl
side-chain, was also one of the best inhibitors we have
. Jakobsen, P.; Lundbeck, J. M.; Kristiansen, M.; Breinholt,
J.; Demuith, H.; Pawlas, J.; Torres Candela, M. T.;
Andersen, B.; Westergaardt, N.; Lundgren, K.; Asano, N.
Bioorg. Med. Chem. 2001, 9, 733.
found to date on b-glucosidase with a K value of
i
6
pointed out that glycosidase activity appeared with an
iminosugar bearing a short alkyl side-chain (compound
1 lM. In this cis-3,4 iminosugar series, it should be
7. Mehta, A.; Zitzmann, N.; Rudd, P. M.; Block, T. M.;
Dwek, R. A. FEBS Lett. 1998, 430, 17.
8
. Asano, N.; Kizu, H.; Oseki, K.; Tomioka, E.; Matsui, K.;
Okamoto, M.; Baha, M. J. Med. Chem. 1995, 38, 2349.
. Butters, T. D.; Dwek, R. A.; Platt, F. M. Chem. Rev. 2000,
13a) but this was not observed in the trans-3,4 series.
Unfortunately, no marked specificity was observed.
9
1
0. Mellor, H. R.; Neville, D. C. A.; Harvey, D. J.; Platt, F.
00, 4683.
1
In this work, we have developed an efficient and
flexible synthesis of novel 5-deoxyadenophorine ana-
logues 12b–e and 13a,d in seven steps from the
common amino alcohol 15 and with good overall
yields. The preliminary structure–activity relationship
study has shown a dependence of the inhibitory
activity upon the 2,3-3,4 cis/trans or cis/cis stereo-
chemistry of the molecules and a dependence of
the potency upon the length of the alkyl side-chain.
Therefore, b-galactosidase activity was only observed
with the cis-3,4 derivatives 13a and 13d but the
inhibitory effect was more efficient on b-glucosidase
M.; Dwek, R. A.; Butters, T. D. Biochem. J. 2004, 381,
8
1. Mellor, H. R.; Neville, D. C. A.; Harvey, D. J.; Platt, F.
M.; Dwek, R. A.; Butters, T. D. Biochem. J. 2004, 381,
867.
12. Jeckel, D.; Karrenbuaer, A.; Burger, K. N.; van Meer, G.;
Wieland, F. J. Cell Biol. 1992, 117, 259.
3. Overkleeft, H. S.; Renjema, G. H.; Neele, J.; Vianello, P.;
Hung, I. O.; Strijland, A.; van der Burg, A. M.; Joomen,
G.-J.; Pandit, U. K.; Aerts, J. M. F. G. J. Biol. Chem.
1998, 273, 26522.
4. Andersson, U.; Butters, T. D.; Dwek, R. A.; Platt, F. M.
Biochem. Pharmacol. 2000, 59, 821.
15. Godin, G.; Compain, P.; Martin, O. R.; Ikeda, R.; Yu, L.;
Asano, N. Bioorg. Med. Chem. Lett. 2004, 14, 5991.
61.
1
1
1
with compounds bearing a C7 (13d: K = 61 lM) or
i
a C11 (12e: K = 58 lM) alkyl side-chain. The trans-
i
3
,4 series also showed a marked structure–activity
16. Boucheron, C.; Desvergnes, V.; Compain, P.; Martin, O.
R.; Lavi, A.; Mackeen, M.; Worlmald, M.; Dwek, R.;
Butters, T. D. Tetrahedron: Asymmetry 2005, 16, 1747.
relationship dependent on the length of the 1-C-al-
kyl side-chain with a-glucosidase but the results
only began to be interesting with compound 12e
with the 1-C–C11 substituent. However, these origi-
nal iminosugars with a lipophilic alkyl chain could
be designed as potential ceramide glycosyltransferase
inhibitors as already demonstrated in the literature.
Now, we are focusing our work on the synthesis
of enantiomerically pure forms of compounds 12
and 13 starting from both enantiomers of Garner’s
1
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m
substrate concentration equal to the calculated K . For
enzymes running at low pH, the reaction was stopped by
1
adding 400 mM Na CO solution. The released p-nitro-
3
2
1
phenol was measured spectrophotometrically at 405 nm.
The potential inhibitors were first tested at a final
concentration of 1 mM and when the percentage of
5
2
2
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from green coffee bean and Aspergillus were purchased
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optimum pH and temperature according to the enzyme,
using the corresponding p-nitrophenyl glycoside at a
inhibition was higher than 40%, the K were determined
i
according to the Lineweaver–Burk method, assuming that
the inhibition kinetics were of competitive type.
25. Ikeda, K.; Takahashi, M.; Nishida, M.; Miyauchi, M.;
Kizu, H.; Kameda, Y.; Arisawa, M.; Watson, A. A.; Nash,
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