Polycations. 17. Synthesis and properties of polycationic derivatives of carbohydrates

Article abstract of DOI:10.1016/j.carres.2009.04.021

In our continuing investigation of polycationic salts for purposes of antimicrobial action, ion-channel blocking, and construction of ionic liquids, we have prepared several series of polycationic salts derived from carbohydrate precursors. These salts are currently being investigated for optimal efficacy as antibacterials and antifungals, as well as for other applications. The syntheses of such series of salts are described here along with preliminary antibacterial testing results and a discussion of their properties indicating their potential utility for several purposes.

Full text of DOI:10.1016/j.carres.2009.04.021

Carbohydrate Research 344 (2009) 1620–1627
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Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Polycations. 17. Synthesis and properties of polycationic derivatives
of carbohydrates
Marie Thomas a,b, Diego Montenegro a, Alejandra Castaño a, Laura Friedman a, Jay Leb a, Mia Lace Huang a,
Leah Rothman a, Heidi Lee a, Craig Capodiferro a, Daniel Ambinder a, Eva Cere a, Jessica Galante a,
JaimeLee Rizzo c, Karin Melkonian d, Robert Engel a,
*
a Department of Chemistry and Biochemistry, Queens College CUNY, 65-30 Kissena Boulevard, Flushing, NY 11367, USA
b Doctoral Program in Chemistry, The Graduate Center CUNY, 365 5th Avenue, New York, NY 10016, USA
c Department of Chemistry and Physical Sciences, Pace University, 1 Pace Plaza, New York, NY 11560, USA
d Department of Biology, Long Island University/C.W. Post Campus, 720 Northern Boulevard, Greenville, NY 11548, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
In our continuing investigation of polycationic salts for purposes of antimicrobial action, ion-channel
blocking, and construction of ionic liquids, we have prepared several series of polycationic salts derived
from carbohydrate precursors. These salts are currently being investigated for optimal efficacy as antibac-
terials and antifungals, as well as for other applications. The syntheses of such series of salts are described
here along with preliminary antibacterial testing results and a discussion of their properties indicating
their potential utility for several purposes.
Received 5 February 2009
Received in revised form 15 April 2009
Accepted 20 April 2009
Available online 24 April 2009
Keywords:
Ó 2009 Elsevier Ltd. All rights reserved.
Cationic carbohydrates
Alditol derivatives
Lipids
Salts
Antibacterial
1. Introduction
ily functionalized. Thus, cellulosic species such as cotton fabric,
paper, and wood are easily rendered antibacterial by the attach-
Significant recent efforts of our laboratories have been directed
toward the development of antimicrobial surfaces that would act
against bacteria and fungi by a disruption of the cell wall.1–6 Crit-
ical differences between the action of such surfaces and the anti-
bacterial action commonly associated with antibiotics include the
following: (a) The mode of action is via an electrostatic disruption
of the existing cell wall subsequent to invasion by a lipophilic
chain of specific length rather than interruption of some metabolic
process; (b) the antimicrobial activity is continual with regard to
the agent since it is not consumed in the process of invasion and
disruption of the cell wall; and (c) it is unlikely that microorgan-
isms could become resistant to this type of attack as it would in-
volve a major modification of their cell-wall structure.
ment of cationic lipid units through the numerous available 6-po-
sition hydroxyl groups that occur at regular and close intervals
throughout the macrosurface.
The challenge for a non-surface activity of this type is to gener-
ate molecules that would bear several cationic lipid components in
close proximity within the structure of the molecule, sufficient to
cause such an effect on an impinging microbe. To this end, we have
synthesized several series of polycationic derivatives of simple car-
bohydrates for investigation of their activity as antimicrobial
agents. Preliminary results of our laboratories indicate this to be
a successful strategy (see below). Our major current concern is
with the syntheses of these agents, although preliminary biological
results are presented herein.
The mode of action of these antimicrobial surfaces depends on a
microbial species impinging on a surface bearing numerous cat-
ionic lipid sites in relatively close proximity, such that the cell wall
is pierced at several sites. This has been demonstrated to be partic-
ularly feasible for surfaces consisting of polymers of carbohydrate
units wherein each unit bears a primary hydroxyl site that is read-
With macrosurfaces, particular antibacterial and antifungal
activities have been noted for the incorporation of lipid chains of
12 and 16 carbons directly attached to a nitrogen of a diazabicy-
clo[2.2.2]octane (DABCO) unit. While the 16-carbon chain species
exhibits activity against the full range of Gram-positive bacteria
and numerous fungi, certain Gram-negative species require a dif-
ferent chain length. Thus, while these chain lengths were most effi-
cacious with macrosurface incorporation, a wider range of chain
lengths and different quaternizing sites have been synthesized
* Corresponding author. Tel.: +1 718 997 4106; fax: +1 718 997 5531.
E-mail address: robert.engel@qc.cuny.edu (R. Engel).
0008-6215/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2009.04.021

M. Thomas et al. / Carbohydrate Research 344 (2009) 1620–1627
1621
for investigation with the microsurface (molecular) species pro-
posed as agents.
equivalent of the appropriate tertiary amine provides a quaternary
ammonium salt derivative of the parent carbohydrate.
There exists a significant body of literature concerning the use
of polycationic species in solution as antibacterial agents. This lit-
erature has been concerned primarily with polycationic species
associated with amino acids and peptidic structures. For example,
a series of structurally diverse cationic peptides have been noted to
exhibit an antibacterial action on Staphylococcus aureus involving
attack on the cytoplasmic membrane.8 Further, introduction of a
fatty acyl chain into the structure of a biologically inactive peptide
provided the species with antibacterial (as well as with antifungal)
activity.9 Yet again, antibacterial activity toward a broad range of
Gram-positive and Gram-negative bacteria has been noted for
low-molecular-weight hydrogels generated using amino acid-
based cationic amphiphiles.10 For the present, we would also note
that the effect of chain length and amino acid content of cationic
peptides has been investigated with regard to their antibacterial
activity.11
The design of polycationic carbohydrate species for these pur-
poses appears to us to be a correspondingly suitable approach for
the development of potential antibacterial pharmaceutical agents.
Such species, derived from biological materials, provide important
capabilities for selective binding at associated sites, thereby
enhancing the capability of such species to serve their intended
purposes. Further, they need to be subject to normal biological
degradation processes that would lead to their removal from the
organism once the antibacterial task is completed. This is a critical
aspect for an antibacterial pharmaceutical agent; without such a
characteristic allowing removal from the organism, continued
activity would be present removing all microorganisms from it to
its detriment. Further, proper design of the carbohydrate-derived
scaffolding can allow a significantly greater charge density species
to impinge upon the bacterial cell wall, a factor that has been noted
not only in our earlier work,1 but also in studies with other sur-
faces modified with polycationic species.12
In addition to
a
series of 1-alkyl-1-azonia-4-azabicy-
clo[2.2.2]octane salts prepared by previously reported methods
in our laboratories,6,13–16 several other tertiary amine species have
been used for the construction of novel derived quaternary ammo-
nium ion species. These mono-tertiary amines along with the
resultant derived methyl
in Table 1.
a-D-glycopyranoside species are shown
2.3. Alditols
Alditols, bearing two primary hydroxyl groups per molecule, in
addition to the several secondary alcohol sites, are readily tosylat-
ed selectively at the two primary hydroxyl sites. Thereby, introduc-
tion of two cationic units per scaffold molecule is readily
accomplished. While mannitol has been the alditol of use in most
of the new species synthesized, an important derivative of glycerol
has also been constructed in which a single secondary hydroxyl
site remains after introduction of the cationic units. The newly
constructed molecules and their tertiary amine precursors are
shown in Table 2.
2.4. Physical properties
The polycationic carbohydrate derivatives are generally hygro-
scopic, rendering the measurement of their melting points often
difficult and causing them often to analyze as hydrates of the par-
ent species. As anticipated, as the size of the cation increases, the
melting point also increases. The mannitol derivatives 22–25 were
found to be insoluble in acetone, dichloromethane, ether, ethyl
acetate, hexanes, acetonitrile, and toluene. Further, the mannitol
derivatives 23–25 gelate water. Compound 25 forms a clear gel
in water with a w/v of 5.3%. This surfactant also forms a clear gel
with ethanol (w/v 6.7%). Both gels were stable for up to two weeks.
The surfactant 24 forms an opaque white gel with water at a w/v of
10%. This gel was found to be stable for at least 22 months. Surfac-
tant 23 formed an unstable gel with water (w/v 30%), but a very
stable gel with ethanol (w/v 3.3%). These gels are of particular
interest in applications for antibacterial medical adjuncts. As antic-
In addition, efforts of collaborating laboratories7 have indicated
utility of related polycationic species as potential pharmaceutical
agents acting as critical ion-channel regulators. Finally, in another
area of potential application for these materials, the results of our
efforts in the preparation of unique ionic liquids (liquid ionic phos-
phates, among others) suggest that carbohydrate-related cationic
components of such materials can provide highly selective species
that can fulfill the promise of ionic liquids to serve as ‘designer sol-
vents’. To these ends, we report the syntheses and properties of
several series of polycationic carbohydrate derivatives.
ipated, the surfactants 9–12 derived from methyl
a-D-glucopyran-
oside exhibit lower melting points than do their mannitol
counterparts. The melting points of the lower molecular weight
salts exhibit some variability when compared to those of their
mannitol counterparts. For example, 7 has a melting point range
of 133–135 °C, which is quite similar to that of the mannitol deriv-
ative 21 (132–136 °C), and the methyl a-D-glucopyranoside deriv-
2. Results and discussion
2.1. General
ative 6 has a large melting point range (60–69 °C) that is higher
than that of its mannitol-derived counterpart 18 (56–66 °C). Simi-
larly, the melting point range for 2 (127–131 °C) is higher than that
for the related mannitol derivative 20 (108–112 °C). For the methyl
Several series of carbohydrates have been modified by the
attachment of cationic lipid sites to the fundamental framework.
a-D-glucopyranoside derivatives, 9–12 were insoluble in the com-
mon organic solvents diethyl ether, ethyl acetate, dichlorometh-
ane, hexane, acetonitrile, and toluene. Only 12 has been found to
gelate water (with a w/v of 5%) and ethanol (with a w/v of 6.7%).
Gelation results are summarized in Table 6.
Most notably these include methyl
a-D-glucopyranoside, and the
reduced carbohydrate species -mannitol.
D
2.2. Methyl a-D-glucopyranoside
2.5. Synthesis
The glycoside is readily activated at the 6-position primary hy-
droxyl group for nucleophilic substitution by reaction with p-tolu-
enesulfonyl chloride in pyridine or in aqueous sodium bicarbonate
solution. This action functionalizes only the 6-position hydroxyl
group leaving the remaining sites for other reactions. Isolation of
the tosylate ester by evaporation of the pyridine or aqueous solu-
tion under reduced pressure at low temperature is easily accom-
plished. Use of the tosylate in acetonitrile solution with an
The syntheses of new polycationic salts from the alditols are
accomplished in a manner similar to that used for the derivatives
of methyl-a-D-glucopyranoside. That is, the parent alditol was
treated with 2 equivalents of p-toluenesulfonyl chloride and
2 equivalents of sodium bicarbonate in water. After partial evapo-
ration of the water at reduced pressure without heating, 2 equiv of
the appropriate tertiary amine were added, and the product was

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M. Thomas et al. / Carbohydrate Research 344 (2009) 1620–1627
Table 1
Derivatives of methyl a-D-glucopyranoside and the tertiary amines used in their construction
Product number
Product structure
Parent tertiary amine
1
+
+
+
N
N
CH(CH3 )2
Br-
N
N
CH(CH3 )2
Br-
O
OTs-
HO
HO
OH
OCH3
2
+
+
+
N
N
CH2 CH(CH3
Br-
)
N
N
CH2 CH(CH3 )2
Br-
2
O
OTs-
HO
HO
OH
OCH3
3
CH3
CH3
N
N
+
N
N
O
OTs-
HO
HO
OH
OCH3
4
+
+
+
N
N
(CH2 )3 CH3
Br-
N
N
(CH2 )3 CH3
Br-
O
OTs-
HO
HO
OH
OCH3
5
N(CH3
)
2
N
N(CH3 )2
+
N
O
OTs-
HO
HO
OH
OCH3
6
N
H3 C
+
CH3
N
OTs-
O
HO
HO
OH
OCH3
7
+
+
+
N
N
CH2 C6 H5
Cl-
N
N
CH2 C6 H5
Cl-
O
OTs-
HO
HO
OH
OCH3
8
+
+
+
N
N
(CH2 )7 CH3
N
N
(CH2
)7 CH3
Br-
Br-
O
OTs-
HO
HO
OH
OCH3

M. Thomas et al. / Carbohydrate Research 344 (2009) 1620–1627
1623
Table 1 (continued)
Product number
Product structure
Parent tertiary amine
9
+
+
+
N
N
N
N
N
(CH2
Cl-
OTs-
)
11 CH3
N
N
N
N
N
N
N
N
(CH2
)11 CH3
Cl-
O
HO
HO
OH
OCH3
10
11
12
13
+
+
+
+
+
+
+
N
(CH2
Br-
OTs-
)
13 CH3
(CH2
Br-
)13 CH3
O
HO
HO
OH
OCH3
+
N
(CH2
Cl-
OTs-
)
15 CH3
(CH2
Cl-
)15 CH3
O
HO
HO
OH
OCH3
+
N
(CH2
Br-
OTs-
)
17 CH3
(CH2 )17 CH3
Br-
O
HO
HO
OH
OCH3
(CH3)2N(CH2)6N(CH3)2
+
+
N
N
2 OTs-
O
O
HO
HO
HO
HO
OH
OH
OCH3
OCH3
14
+
+
+
+
+
+
N
N
(CH2
)
N
N
N
N(CH2 )12
2 Cl-
N
N
N
12
2 Cl-
2OTs-
O
O
HO
HO
HO
HO
OH
OH
OCH3
OCH3
isolated by evaporation of the solvent under reduced pressure. For
all new materials 1H and 13C NMR spectra were measured along
with quantitative elemental analyses and they were found to be
in accord with the proposed structures. These results are given in
Gram-positive bacterium, S. aureus are summarized in Table 6.
While antimicrobial activity was investigated against Escherichia
coli, Pseudomonas aeruginosa, and Aspergillus niger, more detailed
studies were directed toward S. aureus. The gels were tested by
Table 3 for the methyl
a
-D
-glucopyranoside derivatives. Corre-
adding 25
l
L each of the gel and 5 ꢀ 104 S. aureus to Luria–Ber-
sponding data for the alditol derivatives synthesized herein are
presented in Table 4. In addition, melting points and specific rota-
tion data have been obtained for most of the materials, and these
data are presented in Table 5 along with yields for their syntheses.
tani broth. The samples were incubated overnight, and the
change in turbidity of the medium was noted as a measure of
the bacterial growth. Each incubation experiment was performed
with an accompanying control run (no gel added) to determine
the extent of growth inhibition. These results are presented in
Table 7. In all instances, the growth of bacteria in the presence
of the gel was less than 2% of the growth in the absence of
gel. The system has not been optimized for activity, either with
regard to amount of gel or time of incubation.
2.6. Gels
The gels prepared with these polycationic carbohydrate sur-
factants are anticipated to exhibit antimicrobial properties. Other
carbohydrate-based cationic surfactants have been synthesized
with the goal of developing new antimicrobial agents for topical
disinfection.17 Our new materials were found to exhibit such
antimicrobial properties against a range of Gram-positive and
Gram-negative bacteria and one fungal species. Results for the
2.7. Antibacterial activity
The antibacterial activity of a selection of the polycationic car-
bohydrate-derived salts has been investigated with regard to S.

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M. Thomas et al. / Carbohydrate Research 344 (2009) 1620–1627
Table 2
Derivatives of alditols and the tertiary amines used in their construction
Product number
Product structure
Parent tertiary amine
15
+
+
+
N
N
(CH2 )15 CH3
N
N
N
(CH2 )15 CH3
(CH2 )15 CH3
HO
H
4 Cl-
Cl-
+
N
+
16
H OH
H OH
N
N
+
N
N
N
H
OH H OH
2 OTs-
N +
17
H OH
H
H OH
N
+
N
N(CH3 )2
+
N
OH H OH
N(CH3
)
2
2 OTs-
N(CH3
)
2
18
H OH
H3 C
H OH
CH3
N
N
+
H3 C
+
N
H
OH H OH
2 OTs-
19
+
+
N
CH(CH3
)
CH(CH3 )2
Br-
2
H OH
N
H OH
+
N
N
N
+
+
2 Br-
2OTs-
N
+
H OH H OH
(CH3
)
2 CH
20
+
+
N
CH2 CH(CH3
)
CH2 CH(CH3 )
Br-
H OH
N
H OH
+
N
N
N
+
+
2 Br-
2OTs-
N
+
H
OH H OH
(CH3 )2 CHCH2
21
+
+
N
CH2 C6 H5
CH2 C6 H5
Cl-
H OH
N
H OH
+
N
N
N
+
+
2 Cl-
2OTs-
N
+
H
OH H OH
H5 C6 CH2
22
+
+
N
(CH2
)
11 CH3
(CH2 )11 CH3
Br-
H OH
N
H OH
+
N
N
N
+
+
2 Br-
2OTs-
N
+
H
OH H OH
CH3 (CH2
)
11

M. Thomas et al. / Carbohydrate Research 344 (2009) 1620–1627
1625
Table 2 (continued)
Product number
Product structure
Parent tertiary amine
23
+
N
+
N
(CH2 )13 CH3
(CH2 )13 CH3
H OH
H OH
Br-
+
N
N
N
+
+
+
+
2 Br-
2OTs-
N
+
H
OH H OH
CH3 (CH2 )13
CH3 (CH2 )15
CH3 (CH2 )17
24
+
N
+
(CH2 )15 CH3
(CH2 )15 CH3
H OH
N
H OH
Cl-
+
N
N
N
+
2 Cl-
2OTs-
N
+
H
OH H OH
25
+
N
+
N
(CH2 )17 CH3
(CH2
)17 CH3
H OH
H OH
Br-
+
N
N
N
+
2 Br-
2OTs-
N
+
H
OH H OH
Table 3
Newly synthesized cationic derivatives of methyl
a-D-glucopyranoside
Product
number
1H NMR (solvent) (d)
13C NMR (d)
Analysis
Calcd for
C23H39BrN2O8Sꢁ8.5H2O: C,
37.50; H, 7.66. Found: C, 37.53;
H, 7.37
1
(D2O) 1.36 (6H) d, 2.31 (3H) s, 3.33 (3H) s, 3.28–3.80
(20H) br, 7.28–7.62 (4H) AA0BB0
15.5, 20.5, 44.0, 47.8, 55.1, 60.6, 68.3, 69.6, 71.2, 71.6, 73.1, 99.3,
125.4, 129.5, 139.5, 142.5
2
(D2O) 1.01 (6H) d, 2.21 (1H) br, 2.30 (3H) s, 3.35 (3H)
s, 3.33–3.87 (21H) m, 7.27–7.60 (4H) AA0BB0
20.6, 21.9, 22.9, 44.0, 51.2, 55.1, 60.6, 69.6, 71.3, 71.6, 73.1, 74.2,
99.3, 125.4, 129.6, 139.6, 142.5
Calcd for C24H41BrN2O8Sꢁ9H2O:
C, 37.94; H, 7.83. Found: C,
38.12; H, 7.79.
3
(D2O) 2.27 (3H) s, 3.32 (3H) s, 3.78 (3H) s, 3.27–3.78
(7H) m, 7.22–7.55 (4H) AA0BB0, 7.55 (2H) br, 8.44
(1H) s
20.5, 35.2, 55.0, 60.6, 69.6, 71.2, 71.6, 73.1, 99.3, 119.9, 122.8, 125.3,
129.4, 135.1, 139.5, 142.4
Calcd for C18H26N2O8Sꢁ3.5H2O:
C, 43.80; H, 6.74. Found: C,
43.59; H, 6.51
4
(D2O) 0.83 (3H) t, 1.28 (2H) m, 1.64 (2H) m, 2.29
(3H) s, 3.29–3.50 (5H) br, 3.69–3.80 (16H) br, 3.81
(3H) br, 7.26–7.58 (4H) AA0BB0
12.7, 18.9, 20.5, 43.9, 46.2, 50.7, 55.0, 60.5, 65.1, 69.5, 71.2, 71.5,
73.0, 99.2, 125.3, 129.5, 139.4, 142.5
Calcd for C24H41BrN2O8Sꢁ5H2O:
C, 41.92; H, 7.48. Found: C,
41.65; H, 7.76
5
(D2O) 2.26 (3H) s, 3.03 (6H) s, 3.30 (3H) s, 3.26–3.77
(7H) m, 6.67 (2H) d, 7.21 (2H) d, 7.54–7.85 (4H)
AA0BB0
20.4, 39.1, 54.9, 60.5, 69.5, 71.2, 71.5, 73.0, 99.2, 106.7, 125.3, 129.4,
139.2, 142.4, 157.1
Calcd for C21H30N2O8Sꢁ2.5H2O:
C, 48.92; H, 6.84. Found: C,
48.83; H, 6.48.
6
(D2O) 1.09–2.08 (4H) br, 2.34 (3H) s, 2.84 (3H) s,
2.97 (2H) m, 3.30–3.37 (5H) br, 3.45–3.92 (7H) br,
7.32–7.64 (4H) AA0BB0
20.5, 22.8, 40.6, 55.0, 55.8, 60.6, 69.6, 71.2, 71.6, 73.1, 99.3, 125.4,
129.5, 139.5, 142.5
Calcd for C19H31NO8Sꢁ7H2O: C,
39.78; H, 7.90. Found: C, 40.01;
H, 8.27
7
(D2O) 2.34 (3H) s, 3.36 (3H) s, 3.32–3.84 (19H) br,
4.66 (2H) br, 7.32–7.64 (9H) br
20.5, 44.1, 50.6, 55.0, 60.6, 69.0, 69.6, 71.3, 71.6, 73.1, 99.3, 125.4,
126.3. 129.5, 129.6, 131.4, 133.0, 139.5, 145.5
Calcd for C27H39ClN2O8Sꢁ4H2O:
C, 50.54; H, 6.99. Found: C,
50.51; H, 7.00
8
(D2O) 0.76 (3H) t, 1.17–1.24 (10H) br, 1.69 (2H) br,
2.29 (3H) s, 3.36 (3H) s, 3.30–3.78 (21H) br, 7.26–
7.58 (4H) AA0BB0
13.3, 20.4, 21.3, 21.9, 25.2, 28.0, 28.1, 30.9, 43.9, 50.7, 55.0, 60.5,
65.3, 71.2, 71.5, 73.0, 99.2, 125.3, 129.4, 139.4, 142.5
Calcd for C28H49BrN2O8Sꢁ2H2O:
C, 48.76; H, 7.74. Found: C,
48.77; H, 7.80
9
(D2O) 0.84 (3H) t, 0.86–1.01 (18H) br, 1.24 (2H) br,
2.19 (3H) s, 3.32 (3H) br, 3.43–3.76 (21H) br, 7.08–
7.57 (4H) AA0BB0
13.7, 20.8, 21.2, 22.5, 23.8, 28.2, 29.3, 29.4, 29.6, 29.7, 30.2, 31.8,
43.9, 46.9, 50.9, 55.0, 60.5, 69.5, 71.2, 71.5, 73.0, 99.2, 125.6, 129.1,
139.8, 141.2
Calcd for C32H57BrN2O8Sꢁ2H2O:
C, 51.53; H, 8.24. Found: C,
51.46; H, 8.31
10
11
12
13
14
(D2O) 0.84 (3H) t, 0.86–1.01 (22H) br, 1.24 (2H) br,
2.19 (3H) s, 3.32 (3H) s, 3.43–3.76 (21H) br, 7.04–
7.58 (4H) AA0BB0
(D2O) 0.81 (3H) t, 1.19 (26H) br, 1.69 (2H) br, 2.15
(3H) s, 3.32 (3H) s, 3.44–3.87 (21H) br, 6.94–7.55
(4H) AA0BB0
(D2O) 0.86 (3H) t, 1.24 (30H) br, 1.69 (2H) br, 2.29
(3H) s, 3.04 (2H) br, 3.31 (3H) s, 3.19–3.85 (19H) br,
7.11–7.47 (4H) AA0BB0
(D2O) 1.22 (4H) br, 1.55 (4H) br, 2.88 (12H) s, 2.93
(8H) br, 3.25 (6H) s, 3.42–3.76 (16H) br, 7.20–7.60
(8H) AA0BB0
13.9, 21.0, 21.7, 21.9, 22.8, 26.0, 26.3, 29.1, 29.7, 29.8, 30.0, 30.1,
32.2, 44.1, 46.4, 50.8, 55.1, 60.6, 64.7, 69.6, 71.3, 71.6, 73.2, 99.3,
125.8, 129.1, 139.8, 142.1
14.1, 21.2, 22.7, 26.1, 26.9, 28.9, 29.4, 29.5, 29.66, 29.68, 29.73, 29.8,
29.9, 32.7, 44.2, 45.2, 50.6, 55.3, 60.8, 69.7, 71.6, 71.7, 73.4, 99.3,
125.8, 129.1, 140.1, 141.9
13.9, 21.2, 22.0, 22.8, 24.3, 26.2, 26.9, 28.9, 29.44, 29.47, 29.50, 29.6,
29.67, 29.70, 29.75, 29.8 29.9, 32.7, 44.6, 45.7, 50.9, 55.4, 61.0, 69.9,
71.6, 71.8, 73.7, 99.6, 125.4, 128.0, 141.0, 142.1
20.5, 23.7, 25.0, 42.5, 55.0, 57.5, 60.5, 69.5, 71.2, 71.5, 73.0, 99.2,
125.3, 129.4, 139.4, 142.4
Calcd for C34H61BrN2O8Sꢁ2H2O:
C, 52.77; H, 8.47. Found: C,
52.83; H, 8.52
Calcd for C36H65ClN2O8Sꢁ5H2O:
C, 46/56; H, 9.55. Found: C,
46.53; H, 9.18
Calcd for C38H69BrN2O8Sꢁ5H2O:
C, 51.63; H, 9.01. Found: C,
5155; H, 9.23
Calcd for C38H64O16N2S2ꢁ2H2O:
C, 50.43; H, 7.57. Found: C,
50.21; H, 7.83
(D2O) 1.12–1.43 (16H) br, 1.64 (4H) br, 2.26 (6H) s,
3.25 (6H) s, 3.29–3.76 (42H) br, 7.23–7.58 (8H)
AA0BB0
20.5, 21.4, 25.3, 28.1, 28.5, 30.2, 43.9, 50.6, 55.0, 60.5, 65.3, 69.5,
71.2, 73.0, 99.2, 125.3, 129.5, 139.5, 142.4
Calcd for
C52H88Cl2N4O16S2ꢁ2H2O: C.
52.21; H, 7.75. Found: C, 52.08;
H, 7.91

1626
M. Thomas et al. / Carbohydrate Research 344 (2009) 1620–1627
Table 4
Newly synthesized cationic derivatives of alditols
Product
number
1H NMR (solvent) (d)
13C NMR (d)
Analysis
15
16
(D2O) 0.77 (6H) t, 1.04–1.27 (56H) br, 3.11–3.37
(28H) br, 3.37–4.01 (5H) br
(D2O) 2.26 (6H) s, 3.55–3.78 (8H) m, 3.78 (6H) s,
7.23–7.58 (8H) AA0BB0, 7.57 (4H) m, 8.44 (2H) s
13.8, 21.6, 22.6, 23.7, 28.5, 29.19, 29.23, 29.55, 29.61, 29.70, 29.76,
29.82, 29.89, 30.05, 30.20, 44.23, 45.59, 51.0, 52.1, 64.2, 70.3
20.4, 35.2, 63.2, 69.2, 70.8, 119.9, 122.8, 125.3, 129.4, 135.0, 139.3,
142.4
Calcd for C47H96Cl4N4O: C, 61.96;
H, 11.06. Found: C, 61.82; H, 11.11
Calcd for C30H38N2O10S2ꢁH2O: C,
51.71; H, 5.79. Found: C, 51.80; H,
6.01
17
18
(D2O) 2.28 (6H) s, 3.03 (12H) s, 3.51–3.75 (8H) br,
6.69–7.88 (8H) AA0BB0, 7.23–7.56 (8H) AA0BB0
(D2O) 2.00 (8H) br, 2.34 (6H) s, 2.85 (6H) s, 2.98
(4H) br 3.60–3.83 (12H) br, 7.32–7.64 (8H) AA0BB0
20.4, 39.1, 63.2, 69.2, 70.8, 106.8, 125.3, 129.4, 139.4, 140.1, 142.4,
157.0
20.5, 22.8, 40.6, 55.8, 63.2, 69.3, 70.9, 125.4, 129.5, 139.5, 142.5
Calcd for C34H46N4O10S2: C, 55.57;
H, 6.31. Found: C, 55.21; H, 6.63
Calcd for C30H48N2O10S2ꢁH2O: C,
53.03; H, 7.42. Found: C, 53.22; H,
7.69
19
(D2O) 1.36 (12H) d, 2.31 (6H) s, 3.55–3.78 (34H)
br, 7.30–7.60 (8H) AA0BB0
15.5, 20.6, 44.0, 47.8, 63.3, 68.4, 69.3, 125.4, 129.6, 139.6, 142.6
Calcd for
C38H64Br2N4O10S2ꢁ14.5H2O: C,
37.35; H, 7.67. Found: C, 37.26; H,
7.69
20
21
(D2O) 1.01 (12H) d, 2.24 (2H) br, 2.31 (6H) s, 3.32
20.5, 21.8, 22.8, 44.0, 51.3, 63.2, 69.3, 70.9, 72.8, 125.4, 129.4, 139.5,
142.5
Calcd for C40H68Br2N4O10S2: C,
41.10; H, 7.59. Found: C, 40.85; H,
7.30
(4H) d, 3.58–3.86 (32H) br, 7.27–7.62 (8H) AA0BB0
(D2O) 2.28 (6H) s, 3.67–3.84 (32H) br, 4.62 (4H) s,
7.25–7.58 (8H) AA0BB0, 7.45–7.49 (10H) br
20.5, 44.0, 50.5, 63.2, 69.0, 69.3, 70.9, 125.0, 125.4, 129.5, 129.6,
131.5, 133.0, 139.5, 142.5
Calcd for
C46H64Cl2N4O10S2ꢁ12.5H2O: C,
46.30; H, 7.52. Found: C, 46.30; H,
7.58
22
23
24
25
(D2O) 0.51 (6H) t, 1.10–1.20 (36H) br, 1.58 (4H)
br, 2.25 (6H) s, 3.20 (4H) br, 3.48–3.69 (32H) br,
7.18–7.57 (8H) AA0BB0
13.7, 20.7, 21.3, 22.6, 23.8, 28.4, 29.4, 29.5, 29.6, 29.8, 30.2, 31.9,
46.9, 55.1, 60.5, 71.2, 73.1, 99.2, 125.7, 129.2, 139.9, 141.2
Calcd for
C
56H100Br2N4O10S2ꢁ3H2O: C,
53.07; H, 8.43. Found: C, 52.96; H,
8.48
Calcd for
(D2O) 0.51 (6H) t, 1.10–1.20 (44H) br, 1.58 (4H)
br, 2.25 (6H) s, 3.20 (4H) br, 3.48–3.69 (32H) br,
7.18–7.57 (8H) AA0BB0
13.8, 21.0, 21.8, 21.9, 22.7, 26.1, 26.3, 29.2, 29.8, 30.0, 30.2, 32.2,
44.0, 46.4, 55.1, 60.7, 64.7, 71.2, 73.2, 99.3, 125.9, 129.2, 139.8,
142.2
C60H108Br2N4O10S2ꢁ3H2O: C,
54.45; H, 8.68. Found: C, 54.37; H,
8.72
Calcd for
(D2O) 0.86 (6H) t, 1.24 (56H) br, 2.29 (6H) s, 3.36–
3.68 (36H) br, 7.11–7.48 (8H) AA0BB0
14.2, 21.2, 22.7, 26.1, 26.9, 28.9, 29.4, 29.5, 29.6, 29.7, 29.81, 29.84,
21.89, 32.7, 44.3, 45.2, 55.3, 60.8, 69.7, 71.8, 73.4, 99.3, 125.9, 129.2,
140.1, 141.9
C
64H116Cl2N4O10S2ꢁ2H2O: C,
65.55; H, 10.31. Found: C, 65.42;
H, 10.37
(D2O) 0.86 (6H) t, 1.24 (60H) br, 1.68 (4H) br, 2.29
(6H) s, 3.28–3.66 (36H) br, 7.14–7.48 (8H) AA0BB0
13.4, 21.2, 22.1, 22.8, 24.4, 26.2, 28.8, 29.41, 29.48, 29.51, 29.58,
29.68, 29.70, 29.76, 29.80, 32.7, 45.7, 50.2, 55.5, 69.9, 71.7, 71.8,
73.7, 99.6, 125.5, 128.1, 141.0, 142.1
Calcd for
C68H124Br2N4O10S2ꢁ9H2O: C,
52.90; H, 9.27. Found: C, 53.10; H,
9.14
Table 6
aureus. Minimum inhibitory concentrations have been measured
for these salts, and the results are presented in Table 8. From these
results, it becomes evident that, while antibacterial effects can be
Gelation of solvents by newly synthesized polycationic carbohydrate derivativesa
Product number
Water
Ethanol
1-Butanol
12
19
21
22
23
24
25
G
S
S
G
I
I
S
I
I
X
X
G
I
Table 5
Melting points and specific rotation data for newly synthesized compounds
S
I
Product number Melting point (°C) Specific rotation ½a D25
1
2
3
4
5
6
7
ꢂ
Synthetic yield (%)
G
G
G
G
G
G
135–138
127–131
Very hygroscopic
102–107
108–110
60–69
133–135
164–166
130–132
128–130
124–128
174–176
105–107
177–179
132–133
Very hygroscopic
106–116
55–66
+46.6
+44.0
+63.5
+22.5
+63.0
+69.8
+39.2
+42.8
+29.3
+33.9
+42.9
+25.3
+61.7
+40.6
Inactive
ꢃ3.08
ꢃ4.8
94
95
89
98
92
90.7
99
99
99
99
91
99
79
83
91
97
59.2
99
99
82
87
96
99
80
97
a
G: forms gel, S: forms solution, I: insoluble, and X: not tested.
Table 7
Results of antibacterial studies of gels with S. aureusa
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Product number
Solvent
% Survival of S. aureus
12
12
24
24
24
25
25
Water
Ethanol
Water
Ethanol
1-Butanol
Water
1
1
2
2
2
1
1
Ethanol
ꢃ97.4
100–108
109–112
132–136
154–157
135–142
158–168
224–230
+1.5
a
These results represent the growth of bacterium in comparison to a blank.
ꢃ20.3
ꢃ4.6
ꢃ1.2
ꢃ7.9
noted for simple salts containing a single lipophilic chain attached
through a cationic site, greater antibacterial activity can be antici-
pated for species where more than one such linkage is present
+1.4
ꢃ2.2

M. Thomas et al. / Carbohydrate Research 344 (2009) 1620–1627
1627
Table 8
material. Yields, analytical data, and characteristics for these prod-
ucts are presented in Tables 4 and 5.
Measured antibacterial activity (MIC) for newly synthesized compounds against S.
aureus
Product MIC
Comments
3.4. Formation of gels
number
(lM)
6
7
8
10
11
15
18
460
5300
Glucopyranoside substituted at 6-position
Glucopyranoside substituted at 6-position
General procedure. The gels were prepared by adding approxi-
mately 100 mg of the carbohydrate derivative to a clean vial. Then
using an Eppendorf pipette, 1.0 mL of distilled water was added.
The vials were sealed, and the mixture was heated to about 70 °C
to allow the solid to dissolve. The solution was then cooled to room
temperature, and the vial was then inverted to see if gelation had
occurred. If there was no flow, it was the indication that a gel had
formed. If gelation occurred, more solvent was added, and the steps
described above were repeated to see if gelation continued. If gela-
tion did not occur, more of the solid was added. Gel formation with
water and other solvents is presented in Table 6.
>10,000 Glucopyranoside substituted at 6-position
270 Glucopyranoside substituted at 6-position
>10,000 Glucopyranoside substituted at 6-position
340 Disubstituted glycerol
>10,000 Mannitol derivative with small ring ammonium at 1- and 6-
positions
22
24
>10,000 Glucopyranoside substituted at 6-position
9.1
2.2
Mannitol derivative with long chain ammonium at 1- and 6-
positions
Mannitol derivative with long chain ammonium at 1- and 6-
positions
25
3.5. Evaluation of antibacterial activity of gels and salts
within the salt. This would allow for multiple interactions with the
bacterial cell wall.
General procedure. The gel (25 lL) and a stock solution of bacte-
ria (5
l
L, ꢄ5 ꢀ 104, S. aureus) were added to Luria–Bertani (LB)
broth (2 mL). The growth medium was incubated overnight at
37 °C in a shaking water bath. The absorbance (abs, indicating tur-
bidity of the medium) at 600 nm was recorded. The results were
reported as percent growth = (abs of sample/abs of blank) ꢀ 100.
The results are provided in Table 7. Minimum inhibitory concen-
trations were determined by preparing serial dilutions of each salt
and adding the same amount of bacteria to each dilution. Dilutions
were incubated overnight at 37 °C in a shaking water bath. Growth
was observed visually.
3. Experimental
3.1. General
All chemicals and solvents used in these syntheses and purifica-
tions were of commercial reagent quality and were used without
further purification. All 1H and 13C NMR spectra were measured
with the samples in commercial deuterated solvents using a Brüker
400-MHz DPX400 instrument. Elemental analyses were performed
by Schwarzkopf Microanalytical Services of Woodside, NY.
Acknowledgments
3.2. Syntheses of 6-position derivatives of methyl
glucopyranoside (1–14)
a-D-
We are grateful to the Magnet Program at the CUNY Graduate
Center and the NYC LSAMP for financial support to one of us
(M.T.), as well as to the Howard Hughes Medical Institute for finan-
cial support of the pre-college research experience. The Pace Uni-
versity Research Award (J.R.), and the PSC–CUNY Research Award
program are thanked for general financial support of this effort.
General procedure. In 100 mL of water 5.0 g (0.026 mol) of
methyl -glucopyranoside was dissolved to which a small excess
a
-D
(2.35 g, 0.028 mol) of NaHCO3 was added, followed by (4.96 g,
0.026 mol, 1 equiv) of p-TsCl. The mixture was stirred for 1 h at
ambient temperature to allow formation of the 6-O-tosyl deriva-
tive. After this time 0.026 mol, 1 equiv, of the appropriate amine
(0.013 mol in the instances of the diamines used for 13 and 14)
was added, and the reaction mixture was stirred under reflux for
14 h. After cooling, the solvent was evaporated under reduced pres-
sure leaving a viscous liquid that became solid when residual sol-
vent was removed under high vacuum. The impure solid was
treated with 95% EtOH and any insoluble materials were removed
by suction filtration. The remaining solvent was then evaporated
under reduced pressure, and the remainder was dried under high
vacuum to provide the target material. Yields, analytical data, and
characteristics for these products are presented in Tables 3 and 5.
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was then added, followed by p-TsCl (10.3 g, 0.054 mol, 2 equiv).
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formation of the
a,x
-O,O0-ditosyl derivative. After this time the
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