Synthesis and evaluation of antitubercular activity of glycosyl thio- and sulfonyl acetamide derivatives

Article abstract of DOI:10.1016/j.bmcl.2008.06.004

A series of glycosyl thioacetamide and glycosyl sulfonyl acetamide derivatives have been prepared following a convenient reaction protocol and evaluated for their antitubercular activity against Mycobacterium tuberculosis H₃₇Rv. Amongst 32 compounds evaluated 3 compounds were effective in inhibiting mycobacterial growth at MIC of 6.25 μg/mL, 6 compounds at MIC of 3.125 μg/mL and 1 compound at MIC of 1.56 μg/mL. All active compounds were found nontoxic in Vero cell lines and mice bone marrow macrophages.

Full text of DOI:10.1016/j.bmcl.2008.06.004

Bioorganic & Medicinal Chemistry Letters 18 (2008) 4002–4005
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis and evaluation of antitubercular activity of glycosyl thio-
and sulfonyl acetamide derivatives q
b
b
Samir Ghosh a, Pallavi Tiwari a, Shashi Pandey a, Anup Kumar Misra a, , Vinita Chaturvedi , Anil Gaikwad ,
*
Shalini Bhatnagar b, Sudhir Sinha b
a Medicinal and Process Chemistry Division, Central Drug Research Institute, Chattar Manzil Palace, Lucknow 226001, UP, India
b Drug Target Discovery and Development Division, Central Drug Research Institute, Lucknow 226001, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of glycosyl thioacetamide and glycosyl sulfonyl acetamide derivatives have been prepared fol-
lowing a convenient reaction protocol and evaluated for their antitubercular activity against Mycobacte-
rium tuberculosis H37Rv. Amongst 32 compounds evaluated 3 compounds were effective in inhibiting
Received 8 April 2008
Revised 8 May 2008
Accepted 3 June 2008
Available online 6 June 2008
mycobacterial growth at MIC of 6.25 lg/mL, 6 compounds at MIC of 3.125 lg/mL and 1 compound at
MIC of 1.56
lg/mL. All active compounds were found nontoxic in Vero cell lines and mice bone marrow
macrophages.
Keywords:
Ó 2008 Elsevier Ltd. All rights reserved.
Glycosyl thioacetamide
Glycosyl sulfonyl acetamide
Antitubercular
Mycobacterial
Cell-wall biosynthesis
Mycobacterium tuberculosis, the causative agent of tuberculosis
(TB), continues to be the greatest single infectious cause of mortal-
ity worldwide, killing roughly two million people annually (one
person dies every 10 s).2 The World Health Organization (WHO)
has estimated that one-third of the world’s population is infected
with Mycobacterium tuberculosis.3 TB is a leading cause of death
amongst people who are HIV-positive (13% of AIDS deaths world-
wide).4 The synergy between tuberculosis and the AIDS epidemic
as well as the surge of multidrug-resistant isolates of M. tuberculosis
has reaffirmed tuberculosis as a primary public health threat.
Although in the recent past, no remarkable breakthrough has
been achieved in the discovery of an efficient drug to encounter
the TB, quest for the development of better, cheaper and faster
drugs continues. In the present context new drugs to treat TB are
urgently required, specifically for their use in a shorter treatment
regimen and to treat multidrug-resistant and latent disease. Devel-
opments of chemotherapeutics that specifically target dormant ba-
cilli and hence provide more effective treatment of latent TB
infections are also in great needs.
mycolic acid,5,6 arabinogalactans and peptidoglycans7 Earlier, sev-
eral reports have appeared for the development of inhibitors of
fatty acid biosynthesis as antitubercular agents.8 A number of re-
ports are also available in the literature for the development of car-
bohydrate-based inhibitors of cell-wall biosynthesis.9 We have
noticed a report from Townsend et al.10 describing a series of alkyl
sulfonyl acetamide derivatives as new class of antitubercular
agents. It has been demonstrated that sulfonyl acetamide deriva-
tives can act as inhibitors of the cell-wall biosynthesis by mimick-
ing the transition state of the b-ketoacyl synthase (KAS) catalyzed
Claisen reaction step of fatty acid biosynthesis.
Taking the clue from Townsend et al.,10 we envisioned that
designing of per-O-acetylated glycosyl sulfonyl acetamide deriva-
tives could be useful in search of antitubercular agents as sulfonyl
acetamide region could act as KAS inhibitor and per-O-acetylated
sugar moiety could serve as a carrier as well as lipophilic tag for
the successful inhibition of cell-wall biosynthesis. Besides this, su-
gar backbone present in the molecules could provide a recognition
site as the cell-wall is composed of carbohydrate structures. We re-
One of the important strategies for the designing of effective
antitubercular agents is to develop inhibitors of Mycobacterial
cell-wall biosynthesis. The cell-wall of Mycobacteria consist of a
wide array of complex fatty acids, such as mycocerosic acid and
O
O
S
R1
NHR2
O
q
See Ref. 1.
R1 = Per-O-acetylated glycosyl; R2 = H, Alkyl
* Corresponding author. Tel.: +91 522 2612411; fax: +91 522 2623405.
E-mail address: akmisra69@rediffmail.com (A.K. Misra).
Figure 1. Proposed inhibitors of cell-wall biosynthesis in Mycobacteria.10
0960-894X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2008.06.004

S. Ghosh et al. / Bioorg. Med. Chem. Lett. 18 (2008) 4002–4005
4003
port herein the synthesis and evaluation of a series of per-O-acet-
ylated glycosyl thioacetamide and sulfonyl acetamide derivatives
as antitubercular agents. Evaluation of the glycosyl sulfonyl acet-
amide derivatives has been excluded considering the fact that ionic
compounds have poor permeability through the mycobacterial
cell-wall (Fig. 1).
HO
Cl
O
Cl
O
3
OH
1
R1NH2
a
b
A series of glycosyl thioacetamide and glycosyl sulfonyl acetam-
ide derivatives have been prepared and evaluated for their
antitubercular activity against M. tuberculosis H37Rv strain. A series
of per-O-acetylated S-glycosyl isothiouronium salts (2) have been
prepared directly from the corresponding free sugars (1) in
one-pot on treatment with acetic anhydride and boron trifluoride
diethyletherate followed by treatment with thiourea at elevated
temperature.11 Treatment of chloroacetamides (4)12 with S-isothio-
uronium salts 2 in the presence of triethylamine furnished glycosyl
thioacetamide derivatives (5a–p) in satisfactory yields (Scheme 1,
Table 1).13 These glycosyl thioacetamide derivatives were oxidized
using m-CPBA14 to furnish glycosyl sulfonyl acetamide derivatives
(6a–p) in excellent yields (Scheme 1, Table 2).15
AcO
NHR1
NH
O
Cl
.
S
NH2 BF3.OEt2
O
4
2
b
AcO
NHR1
NHR1
O
S
O
O
5
c
AcO
O
S
O
6
The glycosyl thioacetamide derivatives (5a–p) and glycosyl
sulphony lacetamide derivatives (6a–p) were evaluated against
M. tuberculosisH37Rvstrains invitro using thestandardMicrodilution
on Agar Method.16 The activities of the compounds were evaluated
O
in terms of minimum inhibitory concentrations (MIC;
Amongst 32 compounds evaluated, compound 5b showed MIC
lg/mL).
Scheme 1. Reagents and conditions: (a) i—acetic anhydride, BF3ꢀOEt2, rt, 20 min;
ii—thiourea, CH3CN, 70 °C; (b) Et3N, CH3CN, rt; (c) m-CPBA, CH2Cl2, rt.
Table 1
Synthesis of glycosyl thioacetamide derivatives (5a–p)
NHR2
R1
Entry
Sugar
Time (min)a
Yield (%)
S
O
1
2
3
4
5
6
7
8
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
-Glucose
-Galactose
-Mannose
-Ribose
-Xylose
-Arabinose
-Lactose
-Cellobiose
-Maltose
-Glucose
-Arabinose
-Lactose
-Glucose
-Arabinose
-Lactose
R1 = 2,3,4,6-tetra-O-acetyl-.b-
D
-glucopyranosyl; R2 = H (5a)
D
-galactopyranosyl; R2 = H (5b)
25
30
30
30
30
20
60
60
60
30
25
40
25
20
35
30
87
85
85
78
80
82
90
80
82
85
83
87
86
80
88
90
R1 = 2,3,4,6-tetra-O-acetyl-b-
R1 = 2,3,4,6-tetra-O-acetyl- -mannopyranosyl; R2 = H (5c)
a-D
R1 = 2,3,4-tri-O-acetyl-b-
R1 = 2,3,4-tri-O-acetyl-b-
R1 = 2,3,4-tri-O-acetyl-b-
D
D
D
-ribopyranosyl; R2 = H (5d)
-xylopyranosyl; R2 = H (5e)
-arabinopyranosyl; R2 = H (5f)
R1 = (2,3,4,6-tetra-O-acetyl-b-
D
-galactopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-b-
-glucopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-b-
-glucopyranosyl; R2 = H (5h)
-glucopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-b-
-glucopyranosyl; R2 = H (5i)
-glucopyranosyl; R2 = C8H17 (5j)
-arabinopyranosyl; R2 = C8H17 (5k)
R1 = (2,3,4,6-tetra-O-acetyl-.b-
-galactopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-.b-
R1 = 2,3,4,6-tetra-O-acetyl-b- -glucopyranosyl; R2 = C12H25 (5m)
R1 = 2,3,4-tri-O-acetyl-b- -arabinopyranosyl; R2 = C12H25 (5n)
R1 = (2,3,4,6-tetra-O-acetyl-b-
R1 = 2,3,4,6-tetra-O-acetyl-b-
D
-glucopyranosyl; R2 = H (5g)
R1 = (2,3,4,6-tetra-O-acetyl-b-
D
D
9
R1 = (2,3,4,6-tetra-O-acetyl-
a
-
D
D
10
11
12
13
14
15
16
R1 = 2,3,4,6-tetra-O-acetyl-.b-
R1 = 2,3,4-tri-O-acetyl-b-
D
D
D
D
-glucopyranosyl; R2 = C8H17 (5l)
D
D
D
-galactopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-b-D
-glucopyranosyl; R2 = C12H25 (5o)
-Glucose
D
-glucopyranosyl; R2 = CH2Ph (5p)
a
Time taken after formation of S-isothiouronium salts.
Table 2
Synthesis of glycosyl sulfonyl acetamide derivatives (6a–p)
Entry
Substrates
Time (min)
Yield (%)
O
S
NHR2
R1
O
O
1
2
3
4
5
6
7
8
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
5o
5p
R
1 = 2,3,4,6-tetra-O-acetyl-b-
D
D
D
-glucopyranosyl; R2 = H (6a)
-galactopyranosyl; R2 = H (6b)
-mannopyranosyl; R2 = H (6c)
60
60
60
60
60
45
90
90
90
60
50
90
60
50
120
100
90
92
87
82
85
86
90
88
85
92
88
94
93
89
95
93
R1 = 2,3,4,6-tetra-O-acetyl-b-
R1 = 2,3,4,6-tetra-O-acetyl-b-
R1 = 2,3,4-tri-O-acetyl-b-
R1 = 2,3,4-tri-O-acetyl-b-
R1 = 2,3,4-tri-O-acetyl-b-
D
D
D
-ribopyranosyl; R2 = H (6d)
-xylopyranosyl; R2 = H (6e)
-arabinopyranosyl; R2 = H (6f)
R1 = (2,3,4,6-tetra-O-acetyl-b-
D
-galactopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-b-
-glucopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-b-
-glucopyranosyl; R2 = H (6h)
-glucopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-b-
-glucopyranosyl; R2 = H (6i)
-glucopyranosyl; R2 = C8H17 (6j)
-arabinopyranosyl; R2 = C8H17 (6k)
R1 = (2,3,4,6-tetra-O-acetyl-b-
-galactopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-b-
R1 = 2,3,4,6-tetra-O-acetyl-b- -glucopyranosyl; R2 = C12H25 (6m)
R1 = 2,3,4-tri-O-acetyl-b- -arabinopyranosyl; R2 = C12H25 (6n)
R1 = (2,3,4,6-tetra-O-acetyl-b-
-galactopyranosyl)-(1 ? 4)-2,3,6-tri-O-acetyl-b-
R1 = 2,3,4,6-tetra-O-acetyl-b- -glucopyranosyl; R2 = CH2Ph (6p)
D
-glucopyranosyl; R2 = H (6g)
R1 = (2,3,4,6-tetra-O-acetyl-b-
D
D
9
R1 = (2,3,4,6-tetra-O-acetyl-
a
-
D
D
10
11
12
13
14
15
16
R1 = 2,3,4,6-tetra-O-acetyl-b-
R1 = 2,3,4-tri-O-acetyl-b-
D
D
D
D
-glucopyranosyl; R2 = C8H17 (6l)
-glucopyranosyl; R2 = C12H25 (6o)
D
D
D
D
D

4004
S. Ghosh et al. / Bioorg. Med. Chem. Lett. 18 (2008) 4002–4005
Table 3
Research Fellowships. A.K.M. thanks DST, New Delhi, for providing
Ramanna Fellowship.
Screening of compounds 5a–p and 6a–p against M. tuberculosis H37Rv strain
Entry
Compound
MIC (l
g/mL)
Vero cell/macrophage cytotoxicity
References and notes
1
2
3
4
5
6
7
8
5a
5b
5c
5d
5e
5f
5g
5h
5i
3.125
1.56
3.125
12.5
NT
NT
NT
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
NT
ND
ND
NT
NT
ND
NT
ND
ND
NT
ND
ND
ND
ND
ND
ND
ND
ND
NT
1. C.D.R.I. communication no. 7337.
2. Khasnobis, S.; Escuyer, V. E.; Chatterjee, D. Expert Opin. Ther. Targets 2002, 6, 21.
3. World Health Organisation, Tuberculosis Fact sheet, March, 2006.
4. Smith, P.; Moss, A. In Epidemiology of Tuberculosis; Bloom, B., Ed.; ASM Press:
Washington, D.C., 1994; p 47.
5. Block, K. In Advances in Enzymology; Meister, A., Ed.; John Wiley and Sons: New
York, 1977; p 1.
6. (a) Brennan, P. J.; Nikaido, H. Annu. Rev. Biochem. 1995, 64, 29; (b) Kolattukudy,
P. E.; Fernandes, N. D.; Azad, A. K.; Fitzmaurice, A. M.; Sirakova, T. D. Mol.
Microbiol. 1997, 24, 263; (c) Volpe, J. J.; Vagelos, P. R. Annu. Rev. Biochem. 1973,
42, 21.
7. (a) Escuyer, V. E.; Lety, M. A.; Torrelles, J. B.; Khoo, K. H.; Tang, J. B.; Rithner, C.
D.; Frehel, C.; McNeil, M. R.; Brennan, P. J.; Chatterjee, D. J. Biol. Chem. 2001, 276,
48854; (b) Khoo, K. H.; Tang, J. B.; Chatterjee, D. J. Biol. Chem. 2001, 276, 3863;
(c) Khasnobis, S.; Zhang, J.; Angala, S. K.; Amin, A. G.; McNeil, M. R.; Crick, D. C.;
Chatterjee, D. Chem. Biol. 2006, 13, 787; (d) Crick, D. C.; Mahapatra, S.; Brennan,
P. J. Glycobiology 2001, 11, 107R; (e) Hancock, I. C.; Carman, S.; Besra, G. S.;
Brennan, P. J.; Waite, E. Microbiology 2002, 148, 3059.
8. (a) Lee, R. E.; Armour, J. W.; Takayama, K.; Brennan, P. J.; Besra, G. S. Biochim.
Biophys. Acta-Lipids Lipid Metabol. 1997, 1346, 275; (b) Chatterjee, D. Curr. Opin.
Chem. Biol. 1997, 1, 579; (c) Bhowruth, V.; Brown, A. K.; Reynolds, R. C.; Coxon,
G. D.; Mackay, S. P.; Minnikin, D. E.; Besra, G. S. Bioorg. Med. Chem. Lett. 2006,
16, 4743; (d) Gobec, S.; Plantan, I.; Mravljak, J.; Svajger, U.; Wilson, R. A.; Besra,
G. S.; Soares, S. L.; Appelberg, R.; Kikelj, D. Eur. J. Med. Chem. 2007, 42, 54.
9. (a) Davis, C. B.; Hartnell, R. D.; Madge, P. D.; Owen, D. J.; Thomson, R. J.; Chong,
A. K. J.; Coppel, R. L.; von Itzstein, M. Carbohydr. Res. 2007, 342, 1773; (b) Owen,
D. J.; Davis, C. B.; Hartnell, R. D.; Madge, P. D.; Thomson, R. J.; Chong, A. K. J.;
Coppel, R. L.; von Itzstein, M. Bioorg. Med. Chem. Lett. 2007, 17, 2274; (c) Bosco,
M.; Bisseret, P.; Constant, P.; Eustache, J. Tetrahedron Lett. 2007, 48, 153; (d) Joe,
M.; Lowary, T. L. Carbohydr. Res. 2006, 341, 2723; (e) Subramaniam, V.; Gurcha,
S. S.; Besra, G. S.; Lowary, T. L. Tetrahedron: Asymm. 2005, 16, 553; (f) Han, J.;
Gadikota, R. R.; McCarren, P. R.; Lowary, T. L. Carbohydr. Res. 2003, 338, 581.
10. Jones, P. B.; Parrish, N. M.; Houston, T. A.; Stapon, A.; Bansal, N. P.; Dick, J. D.;
Townsend, C. A. J. Med. Chem. 2000, 43, 3304.
11. Tiwari, P.; Agnihotri, G.; Misra, A. K. J. Carbohydr. Chem. 2005, 24, 723.
12. Typical experimental method for preparation of 2-chloroacetamide derivatives (4):
To a solution of chloroacetyl chloride (1.0 mmol) in CHCl3 (5 mL) were added
amines (1.2 mmol) and triethlyamine (Et3N; 2.0 mmol) in succession and the
reaction mixture was allowed to stir at room temperature for 30 min. The
reaction mixture was diluted with CH2Cl2 (20 mL) and washed with water. The
organic layer was dried (Na2SO4) and concentrated to dryness under reduced
pressure to yield solid compounds, which were crystallized from EtOH to
furnish 2-chloroacetamide derivatives.
12.5
>12.5
>12.5
>12.5
>12.5
>12.5
>12.5
>12.5
>12.5
3.125
>12.5
6.25
3.125
3.125
>12.5
6.25
12.5
12.5
3.125
25
25
>12.5
>12.5
>12.5
>12.5
>12.5
>12.5
6.25
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
5j
5k
5l
5m
5n
5o
5p
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
6m
6n
6o
6p
NT, non toxic; ND, not done.
MIC, minimum inhibitory concentration.
1.56
3.125
and 18 compounds (5d–o, 6c, 6e, 6f and 6j–o) showed
MIC P 12.5 g/mL. The active compounds were tested for cyto-
l
l
g/mL, compounds 5a, 5c, 5n, 6a, 6b and 6g showed MIC
g/mL, compounds 5p, 6d and 6p showed MIC 6.25 g/mL
l
l
toxicity against Vero cells and mouse bone marrow macro-
phages, and all of them were found nontoxic (Table 3).17 From
the activity profile it was observed that the presence of a pri-
mary amide functionality might be essential for the effective
antitubercular activity. Changes in the stereochemistry in the su-
gar moiety do not affect much in the MIC values. Although, ini-
tially it was believed that sulfonyl acetamide derivatives can
mimic the tetrahedral transition state of the b-keto acyl syn-
thase-catalyzed Claisen reaction step10 in the fatty acid biosyn-
thesis, presence of two loan pair on the sulfur atom in the
thioacetamide derivatives (5a–c, 5n, 5p) may also providing
the required geometry to mimic the above-mentioned transition
state and thus showing good MIC values.
13. Typical experimental method for preparation of glycosyl thioacetamide derivatives
(5a–p):
A suspension of free carbohydrates (1a–i; 10.0 mmol) in acetic
anhydride (1.02 mmol/OH) was placed in an ice bath with continuous
stirring. To the cold suspension of the reaction mixture was added BF3ꢀOEt2
(1.5 mmol). An exothermic reaction started immediately and the reaction
mixture was allowed to stir for 5.0 min. After completion of the per-O-
acetylation, anhydrous CH3CN (10.0 mL) was added to the reaction mixture
followed by thiourea (2.0 mmol) and the reaction mixture was placed on a
preheated oil bath at 80 °C for 15 min with constant stirring. After full
consumption of the sugar per-O-acetates (TLC; EtOAc), the reaction mixture
was cooled to room temperature. To the reaction mixture were added 2-
chloroacetamide derivatives (4; 1.1 mmol) and Et3N (5.0 mL) in succession and
allowed to stir for appropriate time (Table 1) at room temperature. The
solvents were removed and the resulting syrup was diluted with CH2Cl2
(100 mL). The organic layer was washed with water, dried (Na2SO4) and
concentrated under reduced pressure. Purification of the crude reaction
product over SiO2 using hexane-EtOAc (3:1) furnished pure glycosyl
thioacetamide derivatives (5a–p) in satisfactory yields (Table 1).
In conclusion, a series of glycosyl thioacetamide and glycosyl
sulfonyl acetamide derivatives have been synthesized following a
convenient protocol, which can easily be scaled up for the prep-
aration of compounds in higher quantity. These set of com-
pounds have been evaluated for their antitubercular activities
14. (a) Kahne, D.; Walker, S.; Cheng, Y.; van Engen, D. J. Am. Chem. Soc. 1989, 111,
6881; (b) Yan, L.; Kahne, D. J. Am. Chem. Soc. 1996, 118, 9239; (c) Kim, S. H.;
Augeri, D.; Yang, D.; Kahne, D. J. Am. Chem. Soc. 1994, 116, 1766.
15. Typical experimental method for preparation of Glycosyl sulfonyl acetamide
derivatives (6a–p): To a solution of glycosyl thioacetamide derivatives (5a–p;
1.0 mmol) in CH2Cl2 was added m-CPBA (1.5 mmol) and the reaction mixture
was allowed to stir for appropriate time (Table 2). After completion (TLC;
hexane: EtOAc 1:1), the reaction was quenched with aq. FeSO4 solution and
extracted with CH2Cl2. The organic layer was washed with aq NaHCO3 and
water successively, dried (Na2SO4) and concentrated under reduced pressure.
Purification of the crude reaction product over SiO2 using hexane-EtOAc (1:1)
furnished pure glycosyl sulphonyl acetamide derivatives (6a–p) in excellent
yields (Table 2).
against Mycobacterium tuberculosis
H37Rv, using microdilution
on agar method. Some of the compounds (5a–c, 5n, 6a, 6b and
6g) may be considered as potential leads of antitubercular
agents. Further optimization of the lead molecules is currently
in progress in our laboratory.
(2,3,4,6-tetra-O-acetyl-1-sulfonyl-b-
4:0ðc1:0; CHCl3Þ; IR (neat): 3462, 3022, 2362, 1751, 1693, 1596, 1370, 1222,
1066, 765 cmꢂ1 1H NMR (CDCl3, 300 MHz): d 6.68 (br s, 1H, NH2), 5.84 (br s,
D-glucopyranosyl) acetamide (6a):
½ ꢁ ꢂ
a 2D5
Acknowledgments
;
1H, NH2), 5.25 (t, J = 9.0 Hz, 1H, H-2), 5.08 (t, J = 9.0 Hz, 1H, H-3), 5.05 (t,
J = 9.0 Hz, 1H, H-4), 4.62 (d, J = 9.0 Hz, 1H, H-1), 4.22–4.20 (m, 2H, H-6a,b), 3.79–
Instrumentation facilities from SAIF and CDRI are gratefully
acknowledged. S.G. and P.T. thank CSIR, New Delhi, for providing

S. Ghosh et al. / Bioorg. Med. Chem. Lett. 18 (2008) 4002–4005
4005
3.73 (m, 1H, H-5), 3.51–3.21 (ABq, J = 15 Hz, 2H, SO2CH2), 2.10, 2.07, 2.04, 2.00
N-Octyl-2-(2,3,4-tri-O-acetyl-1-sulfonyl-b-
D
-ara-binopyranosyl) acetamide (6k):
(4s, 12H, 4 COCH3); ESI-MS: m/z = 475.9 [M+Na]+; Anal. calcd C16H23NO12
S
½
a 2D5
ꢁ
ꢂ 10:4ðc1:0; CHCl3Þ; IR (neat): 3429, 2927, 2367, 1740, 1592, 1461, 1382,
(453.09): C, 42.38; H, 5.11; found: C, 42.16; H, 5.35.
1351, 1234, 1060, 767 cmꢂ1 1H NMR (CDCl3, 200 MHz): d 5.53 (d, J = 4.2 Hz, 1H,
;
(2,3,4,6-tetra-O-acetyl-1-sulfonyl-b-
D
-galactopyranosyl) acetamide (6b): ½a D25
ꢁ þ
H-4), 5.38–5.26 (m, 3H, H-1, H-2 and H-3), 4.23-4.10 (m, 2H, –SCH2), 3.83–3.79
(m, 2H, H-5ab), 3.28–3.26 (m, 2 H, NHCH2), 2.11, 2.07, 2.04 (3s, 9H, 3 COCH3),
1.55–1.52 (m, 2H, octyl), 1.26–1.25 (m, 10H, octyl), 0.87–0.84 (m, 3 H, CH3); ESI-
MS: m/z = 516.2 [M+Na]+; Anal. calcd C21H35NO10S (493.2): C, 51.10; H, 7.15;
found: C, 50.90; H, 7.34.
7:0ðc1:0; CHCl3Þ; IR (neat): 3460, 3021, 2360, 1752, 1692, 1598, 1372, 1217,
1059, 762, 670 mꢂ1 1H NMR (CDCl3, 300 MHz): d 6.69 (br s, 1H, NH2), 5.87 (br s,
;
1H, NH2), 5.45 (d, J = 3.0 Hz, 1H, H-4), 5.24 (t, J = 9.9 Hz, 1H, H-2), 5.08 (dd, J = 9.9,
3.0 Hz, 1H, H-3), 4.60 (d, J = 9.8 Hz, 1H, H-1), 4.19–4.05 (m, 2H, H-6a,b), 4.00–3.96
(m, 1H, H-5), 3.52–3.19 (ABq, J = 16.4 Hz, 2H, SO2CH2), 2.16, 2.08, 2.06, 1.99 (4s,
12H, 4 COCH3); ESI-MS: m/z = 475.9 [M+Na]+; Anal. calcd C16H23NO12S (453.09):
C, 42.38; H, 5.11; found: C, 42.20; H, 5.30.
N-Octyl-2-[(2,3,4,6-tetra-O-acetyl-b-D-galactopyranosyl)-(1 ? 4)-2,3,6-tri-O-
acetyl-1-sulfonyl-b-
D
-glucopyranosyl] acetamide (6l): ½a D25
ꢂ 12:9ðc1:0; CHCl3Þ;
ꢁ
IR (neat): 3396, 2926, 2857, 2368, 1752, 1591, 1427, 1375, 1229, 1054, 905, 756,
(2,3,4,6-tetra-O-acetyl-1-sulfonyl-
a
-
D
-mannopyranosyl) acetamide (6c):½a D25
ꢁ þ
601 cmꢂ1 1H NMR (CDCl3, 200 MHz): d5.46–5.39 (t, J = 10.2 and 9.3 Hz, 1H, H-3),
;
36:3ðc1:0; CHCl3Þ; IR (neat):3455, 3353, 3022, 2361, 2338, 1753, 1692, 1372,
5.33 (d, J = 2.7 Hz, 1H, H-40), 5.11–5.09 (m, 1H, H-2), 5.07 (d, J = 7.8 Hz, 1H, H-1),
5.03–4.93 (m, 2H, H-20 and H-4), 4.50 (d, J = 7.8 Hz, 1H, H-10), 4.41–4.40 (m, 1H,
H-30), 4.13–4.09 (m, 4 H, H-6ab and H-60ab), 4.02–3.99 (m, 1H, H-5), 3.94–3.89 (t,
J = 9.0 Hz each, 1H, H-50), 3.87–3.82 (m, 2 H, SCH2-), 3.43–3.12 (m, 2H, NHCH2-)
2.19, 2.17, 2.13 (3s, 9H, 3 COCH3), 2.06 (s, 6H, 2 COCH3), 2.01, 1.97 (2s, 6H, 2
COCH3), 1.54–1.51 (m, 2H, octyl), 1.28–1.25 (m, 10H, octyl), 0.92–0.88 (m, 3H, -
CH3); ESI-MS: m/z = 876.2 [M+Na]+; Anal. calcd C36H55NO20S (853.3): C, 50.64; H,
6.49; found: C, 50.47; H, 6.65.
1321, 1217, 1121, 1050, 760, 668 cmꢂ1 1H NMR (CDCl3, 300 MHz):d 6.89 (br s,
;
1H, NH2), 6.32 (br s, 1H, NH2), 5.93 (br s, 1H, H-2), 5.48 (dd, J = 9.3, 3.5 Hz, 1H, H-
3), 5.38 (br s, 1H, H-1), 5.33 (t, J = 9.2 Hz, 1H, H-4), 4.65–4.60 (m, 1H, H-5), 4.29–
4.17 (m, 3H, H-6a,b, SCH2), 4.05 (d, J = 14.7 Hz, 1H, SO2CH2), 2.16, 2.11, 2.07, 2.02
(4s, 12H, 4 COCH3); ESI-MS: m/z = 475.9 [M+Na]+; Anal. calcd C16H23NO12
S
(453.09):C, 42.38; H, 5.11; found:C, 42.20; H, 5.35.
(2,3,4-tri-O-acetyl-1-sulfonyl-b-
15:0ðc1:0; CHCl3Þ; IR (neat):3020, 2927, 2361, 2338, 1752, 1692, 1372, 1216,
1045, 760, 669 cmꢂ1 1H NMR (CDCl3, 300 MHz):d 6.84 (br s, 1H, NH2), 6.40 (br s,
D-ribopyrano-syl)
acetamide
(6d):
½ ꢁ ꢂ
a 2D5
N-Dodecyl-2-(2,3,4,6-tetra-O-acetyl-1-sulfonyl-b-
D
-glucopyranosyl)
ꢂ 4:9ðc1:0; CHCl3Þ; IR (neat): 3434, 2817, 2368, 1751, 1593, 1383,
1H NMR (CDCl3, 200 MHz): d 5.56–5.50 (t,
acetamide
;
(6m): ½a 2D5
ꢁ
1H, NH2), 5.65 (t, J = 2.7 Hz, 1H, H-3), 5.55 (dd, J = 8.3, 3.2 Hz, H-2), 5.13–5.08 (m,
1H, H-4), 4.99 (d, J = 8.3 Hz, 1H, H-1), 4.22–4.10 (m, 2H, H-5a, SO2CH2a), 3.99 (d,
J = 14.6 Hz, 1H, SO2CH2b), 3.88–3.81 (m, 1H, H-5b), 2.16, 2.06, 2.04 (3s, 9H, 3
COCH3); ESI-MS: m/z = 403.9 [M+Na]+; Anal. calcd C13H19NO10S (381.07):C,
40.94; H, 5.02; found:C, 40.75; H, 5.25.
1351, 1238, 1042, 766, 603 cmꢂ1
;
J = 9.3 Hz each, 1H, H-3), 5.15–5.08 (m, 1H, H-2), 4.82 (d, J = 9.9 Hz, 1H, H-1),
4.31–4.23 (m, 2H, H-4 and H-6a), 4.12–3.99 (m, 2H, H-5 and H-6b), 3.95–3.82 (m,
2H, -SCH2), 3.30–3.26 (m, 2H, NHCH2), 2.13, 2.09 (2s, 6H, 2 COCH3), 2.05 (s, 6H, 2
COCH3),1.56–1.52 (m, 2H, CH2), 1.27–1.25 (m, 18H, dodecyl), 0.91–0.87 (t,
(2,3,4-tri-O-acetyl-1-sulfonyl-b-
ðc1:0; CHCl3Þ; IR (neat):3434, 3021, 2360, 1749, 1641, 1376, 1216, 1044, 762,
670 cmꢂ1 1H NMR (CDCl3, 300 MHz):d 7.60 (br s, 1H, NH2), 6.39 (br s, 1H, NH2),
D-xylopyranosyl) acetamide (6e):
½ ꢁ ꢂ 45:5
a 2D5
J = 6.5 Hz, 3H, CH3); ESI-MS: m/z = 644.2 [M+Na]+; Anal. calcd C28H47NO12
S
(621.3): C, 54.09; H, 7.62; found: C, 53.90; H, 7.80.
;
N-Dodecyl-2-(2,3,4-tri-O-acetyl-1-sulfonyl-b-
D
-arabinopyranosyl)
ꢂ 15:2ðc1:0; CHCl3Þ; IR (neat): 3434, 2817, 2368, 1751, 1593, 1383,
1H NMR (CDCl3, 200 MHz): d 5.49 (d, J = 4.2 Hz, 1H,
acetamide
5.63 (t, J = 8.6 Hz, 1H, H-3), 5.41–5.28 (m, 2H, H-2, H-4), 5.02 (d, J = 9.3 Hz, 1H, H-
1), 4.36–4.31 (m, 1H, H-5a), 4.22–3.88 (ABq, J = 14.6 Hz, 2H, SO2CH2), 3.60–3.54
(m, 1 H, H-5b), 2.09, 2.05 (2s, 9H, 3 COCH3); ESI-MS: m/z = 403.9 [M+Na]+; Anal.
calcd C13H19NO10S (381.07):C, 40.94; H, 5.02; found:C, 40.77; H, 5.20.
(6n): ½a 2D5
ꢁ
1351, 1238, 1042, 766 cmꢂ1
;
H-4), 5.34–5.23 (m, 3H, H-1, H-2 and H-3), 4.19–4.07 (m, 2H, -SCH2), 3.78–3.76
(m, 2H, H-5), 3.25–3.23 (m, 2H, NHCH2), 2.10, 2.05, 2.04 (3s, 9H, 3 COCH3), 1.53–
1.50 (m, 2H, dodecyl), 1.26–1.25 (m, 18H, dodecyl), 0.89–0.86 (m, 3H, CH3); ESI-
MS: m/z = 572.2 [M+Na]+; Anal. calcd C25H43NO10S (549.3): C, 54.63; H, 7.88;
found: C, 54.44; H, 8.0.
(2,3,4-tri-O-acetyl-1-sulfonyl-b-
18:0ðc1:0; CHCl3Þ; IR (neat): 3464, 3021, 2360, 1751, 1692, 1372, 1217, 1061,
762, 670 cmꢂ1 1H NMR (CDCl3, 200 MHz): d 6.74 (br s, 1H, NH2), 6.20 (br s, 1H,
D-arabinopyra-nosyl) acetamide (6f):
½ ꢁ ꢂ
a 2D5
;
NH2), 5.73 (t, J = 9.4 Hz, 1H, H-2), 5.35 (br s, 1H, H-4), 5.21 (dd, J = 9.5, 3.3 Hz, 1H,
H-3), 4.86 (d, J = 9.3 Hz, 1H, H-1), 4.24–4.19 (m, 2H, H-5a, SO2CH2), 4.0–3.89 (m,
2H, H-5b, SO2CH2), 2.18, 2.07, 2.03 (3s, 9H, 3 COCH3); ESI-MS: m/z = 404.0
[M+Na]+; Anal. calcd C13H19NO10S (381.07): C, 40.94; H, 5.02; found: C, 40.78; H,
5.20.
N-Dodecyl-2-[(2,3,4,6-tetra-O-acetyl-b-D-galactopyranosyl)-(1 ? 4)-2,3,6-tri-O-
acetyl-1-sulfonyl-b-
D
-glucopyranosyl] acetamide (6o): ½a D25
ꢂ 8:8ðc1:0; CHCl3Þ;
ꢁ
IR (neat): 3400, 2927, 2362, 1752, 1592, 1425, 1373, 1230, 1056, 899, 756 cmꢂ1
;
1H NMR (CDCl3, 200 MHz): d 5.32 (br s, 1H, H-4), 5.22–5.16 (t, J = 9.9 Hz each, 1H,
H-3), 4.97–4.90 (m, 3H, H-10, H-20 and H-2), 4.52–4.47 (m, 3H, H-30, H-40 and H-
1), 4.15–4.07 (m, 2H, H-6ab), 4.06–4.02 (m, 1H, H-5), 3.90–3.75 (m, 2H, H-60ab),
3.65–3.61 (m, 1H, H-50), 3.47–3.16 (m, 4H, SCH2 and NHCH2), 2.16, 2.13, 2.08,
2.07 (4s, 12H, 4 COCH3), 2.05 (s, 6H, 2 COCH3), 1.97 (s, 3H, COCH3), 1.52–1.47 (m,
2H, CH2), 1.29–1.26 (m, 18H, dodecyl), 0.92–0.87 (t, J = 6.6Hz, 3H, CH3); ESI-MS:
m/z = 932.2 [M+Na]+; Anal. calcd C40H63NO20S (909.3): C, 52.79; H, 6.98; found:
C, 52.60; H, 7.20.
(2,3,4,6-tetra-O-acetyl-b-D-galactopyranosyl)-(1 ? 4)-(2,3,6-tri-O-acetyl-1-
sulfonyl-b-
D
-glucopyranosyl) acetamide (6g): ½a D25
ꢁ
þ 3:0ðc1:0; CHCl3Þ; IR (neat):
3464, 3021, 2360, 1753, 1693, 1371, 1216, 1046, 761, 669 cmꢂ1
;
1H NMR (CDCl3,
200 MHz): d 6.81 (br s, 1H, NH2), 6.30 (br s, 1H, NH2), 5.47 (t, J = 9.4 Hz, 1H, H-3),
5.32 (br s, 1H, H-40), 5.26 (t, J = 8.0 Hz, 1H, H-2), 5.08 (t, J = 10.3 Hz, 1H, H-20), 4.96
(dd, J0= 10.4, 3.2 Hz, H-30), 4.84 (d, J = 10.0 Hz, 1H, H-10), 4.63 (d, J = 12 Hz, 1H,
H ꢂ 6a), 4.54 (d, J = 7.6 Hz, 1H, H-1), 4.18–4.03 (m, H-4, H-6a, H ꢂ 60b, SO2CH2a),
H-5, H-50, H-6b, SO2CH2b), 2.12, 2.09, 2.04, 2.03, 2.02, 2.01, 1.93 (7s, 21H, 7
COCH3); ESI-MS: m/z = 764.1 [M+Na]+; Anal. calcd C28H39NO20S (741.2): C,
45.34; H, 5.30; found: C, 45.17; H, 5.50.
N-Benzyl-2-(2,3,4,6-tetra-O-acetyl-1-sulfonyl-b-
D
-glucopyranosyl) acetamide (6p
ꢂ 16:3ðc1:0; CHCl3Þ; IR (neat): 3417, 2820, 2360, 1593, 1444, 1382, 1350,
1H NMR (CDCl3, 200 MHz): d 5.17–5.11 (t, J = 9.3 Hz each,
): ½a 2D5
ꢁ
1241, 1105, 769 cmꢂ1
;
1H, H-3), 5.05–4.99 (m, 3H, H-2 and CH2Ph), 4.54 (d, J = 10.2 Hz, 1H, H-1), 4.22–
4.18 (m, 1H, H-4), 4.07-3.88 (m, 2H, H-6ab), 3.66–3.64 (m, 1H, H-5), 3.50–3.39 (m,
2H, SCH2), 3.21–3.19 (m, 2H, NHCH2), 1.99 (s, 6H, 2 COCH3), 1.98, 1.97 (2s, 6H, 2
COCH3); ESI-MS: m/z = 566.1 [M+Na]+; Anal. calcd C23H29NO12S (543.1): C,
50.82; H, 5.38; found: C, 50.60; H, 5.60.
(2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl)-(1 ? 4)-(2,3,6-tri-O-acetyl-1-sulfonyl-
b-
D
-glucopyranosyl) acetamide (6h): ½a D25
ꢁ
ꢂ 16:0ðc1:0; CHCl3Þ; IR (neat): 3462,
3020, 2361, 2338, 1755, 1692, 1371, 1216, 1046, 760, 669 cmꢂ1
;
1H NMR (CDCl3,
200 MHz): d 6.77 (br s, 1H, NH2), 6.21 (br s, 1H, NH2), 5.49 (t, J = 9.5 Hz, 1H, H-3),
5.29 (t, J = 9.0 Hz, 1H, H-2), 5.15 (t, J = 9.5 Hz, 1H, H-20), 5.09 (t, J = 9.5 Hz, 1H, H-
30), 4.90 (t,J = 9.5 Hz, 1H, H-40), 4.86 (d, J = 9.9 Hz, 1H, H-10), 4.68 (d, J = 11.9 Hz,
1H, H-6a), 4.55 (d, J = 8.0 Hz, 1H, H-10), 4.40–4.34 (m, 1H, H-50), 4.17 (d,
J = 14.7 Hz, 1H, SO2CH2a), 4.14–4.02 (m, 2H, H-4, H-6b), 3.90 (d, J = 14.7 Hz, 1H,
SO2CH2b), 3.88–3.84 (m, 2H, H-60a,b), 3.72–3.69 (m, 1H, H-5), 2.12, 2.07, 2.02,
16. Antitubercular activity18
: Determination of the MIC (minimum inhibitory
concentration) of test compounds or standard anti-TB drugs (rifampicin and
isonoiazid) for M. tuberculosis H37Rv was done using the ‘‘proportion method”.13
Serial twofold dilutions of test compounds were mixed in warm Middlebrook
7H10 agar medium, dispensed in sterile glass tubes (2 mL/tube) and allowed to
1.99, 1.97 (5s, 21H,
28H39NO20S (741.2): C, 45.34; H, 5.30; found: C, 45.15; H, 5.52.
7
COCH3); ESI-MS: m/z = 763.9 [M+Na]+; Anal. calcd
solidify as ‘‘slants”. A homogeneous suspension (10 l
L, containing 105 colony
C
forming units or CFUs) of M. tuberculosis H37Rv was spread over the surface of the
agar medium in each tube and kept at 37 °C for 4 weeks for appearance of
colonies. The minimum concentration of compounds/drugs which completely
(2,3,4,6-tetra-O-acetyl-a-D-glucopyranosyl)-(1 ? 4)-(2,3,6-tri-O-acetyl-1-
sulfonyl-b-
D
-glucopyranosyl) acetamide (6i): ½a D25
ꢁ
þ 34:0ðc1:0; CHCl3Þ; IR (neat):
3470, 3021, 2361, 2339, 1753, 1371, 1217, 1042, 760, 669 cmꢂ1
;
1H NMR (CDCl3,
inhibited bacterial growth was recorded as MIC (lg/mL).
200 MHz): d 6.77 (br s, 1H, NH2), 6.24 (br s, 1H, NH2), 5.42-5.38 (m, 3H, H-20, H-3,
H-30), 5.36 (t, J = 7.5 Hz, 1H, H-2), 5.06 (t, J = 7.4 Hz, 1H, H-40), 4.92 (d, J = 2.0 Hz,
1H, H-10), 4.87 (d, J = 7.5 Hz, 1H, H-1), 4.71 (d, J = 12 Hz, 1H, H-6a), 4.27–4.16 (m,
3H, H-4, H-6b, SO2CH2a), 4.09–3.99 (m, 2H, H-60a,b), 3.97-3.91 (m, 3H, H-5, H-50,
SO2CH2b), 2.14, 2.12, 2.10, 2.05, 2.04, 2.00 (6s, 21H, 7 COCH3); ESI-MS: m/
z = 763.9 [M+Na]+; Anal. calcd C28H39NO20S (741.2): C, 45.34; H, 5.30; found: C,
45.12; H, 5.55.
17. Cytotoxicity measurement19: Selected compounds were tested for their in vitro
cytotoxicity against Vero C1008 cells (African Green Monkey kidney cell line) as
well as mouse bone marrow-derived macrophages using the described method
by Mosmann.14 104 cells/0.2 mL/well (in DME medium containing 10% foetal
bovine serum + antibiotics) were seeded in 96-well tissue culture plates and
incubated for 24 h (at 37 °C, 5% CO2). The medium on top of the cells was
replaced with fresh medium containing serial dilutions of test compounds/
N-Octyl-2-(2,3,4, 6-tetra-O-acetyl-1-sulfonyl-b-
ꢂ 5:6ðc1:0; CHCl3Þ; IR (neat): 3423, 2929, 2363, 1751, 1592, 1452, 1380,
1352, 1236, 1042, 762, 670 cmꢂ1 1H NMR (CDCl3, 200 MHz): d 5.45–5.43 (t,
D-glucopyranosyl) acetamide (6j):
standard toxic compound/DMSO. After 24 h incubation (37 °C, 5% CO2), 20 lL
½ ꢁ
a 2D5
MTS reagent (Promega, USA) was added to each well and absorbance was read
after 2 h at 490 nm. Absorbance shown by DMSO containing wells was taken to
denote 100% cell viability. A compound was considered as toxic if its IC50 value
(concentration causing 50% inhibition of viability) was 10 times the MIC for M.
tuberculosis H37Rv.
;
J = 9.6 Hz, 1H, H-3), 5.16–5.10 (m, 2H, H-1 and H-2), 4.52–4.49 (m, 1H, H-4),
4.30–4.22 (m, 3H, H-5 and H-6ab), 4.12–4.04 (m, 2H, -SCH2), 3.91–3.81 (m, 1H,
NHCH2), 3.35–3.20 (m, 1H, NHCH2), 2.12, 2.09, 2.03, 2.02 (4s, 12H, 4 COCH3),
1.61–1.52 (m, 2H, –CH2), 1.28–1.26 (m, 10H, octyl), 0.93–0.86 (m, 3H, CH3); ESI-
MS: m/z = 588.2 [M+Na]+; Anal. calcd C24H39NO12S (565.2): C, 50.96; H, 6.95;
found: C, 50.75; H, 7.20.
18. McClachy, J. K. Lab. Med. 1978, 9, 47.
19. Mosmann, T. J. Immunnol. Methods 1983, 65, 55.