Synthesis and Antiviral Activity of 3-Aminoindole Nucleosides of 2-Acetamido-2-deoxy-D-glucose

Abstract

A new method for the construction of 3-aminoindole nucleosides of 2-acetamido-2-deoxy-D-glucose based is presented. Nitration and acetylation of the indole nucleosides by acetic anhydride-nitric acid mixture followed by reduction using silver catalyst (SNSM) impregnated on silica gel, afforded the corresponding amino indole nucleosides. The nucleosides were tested for antiviral activity against hepatitis B virus (HBV) to show different degrees of antiviral activities or inhibitory actions.

Full text

Synthesis and Antiviral Activity of 3-Aminoindole Nucleosides Bull. Korean Chem. Soc. 2012, Vol. 33, No. 10 3417
http://dx.doi.org/10.5012/bkcs.2012.33.10.3417
Synthesis and Antiviral Activity of 3-Aminoindole Nucleosides of
2-Acetamido-2-deoxy-D-glucose
Adel A.-H. Abdel-Rahman,†,* Mona M. Abd El-Latif,‡ Farag A. El-Essawy,† and Yousif A. Barakat†,§
†Department of Chemistry, Faculty of Science, Menoufia University, Shebin El-Koam, Egypt. *E-mail: adelnassar63@yahoo.com
‡Dean of Advanced Technology and New Materials Research Institute, City for Scientific Research and Technology Applications,
New Borg El-Arab City, P. O. 21934 Alexandria, Egypt.
§Faculty of Engineering, The British University in Egypt (BUE), El-Sherouk City, Cairo, Egypt.
Received February 14, 2012, Accepted June 21, 2012
A new method for the construction of 3-aminoindole nucleosides of 2-acetamido-2-deoxy-D-glucose based is
presented. Nitration and acetylation of the indole nucleosides by acetic anhydride-nitric acid mixture followed
by reduction using silver catalyst (SNSM) impregnated on silica gel, afforded the corresponding amino indole
nucleosides. The nucleosides were tested for antiviral activity against hepatitis B virus (HBV) to show different
degrees of antiviral activities or inhibitory actions.
Key Words : Nucleosides, Nitroindole, Silver nanoparticles, Antiviral activity
Introduction
Metallic nanoparticles, especially silver nanoparticles,
have attracted much attention because they have already
shown promises in catalysis1-4 and SERS (surface enhanced
Raman scattering) studies.5
Indoles are important in both the biological and material
sciences.6 Among the wide variety of privileged indole
scaffold structures, the novel 3-aminoindole core appeared
only recently. 3-Aminoindole derivatives, though not easily
accessible, have nevertheless emerged as promising agents
with potential application against a large number of di-
seases.7-13 3-Aminoindole-based compounds are commonly
prepared from the corresponding 3-substituted indoles7,8,14-17
indoxyls,9,18 and non-indolic precursors.10-12,19,20
As a part of the program aimed at the development of new
nucleoside derivatives with potential biological activities,21
we describes herein the new method for the construction of
3-aminoindole nucleosides of 2-acetamido-2-deoxy-D-glu-
cose and its antiviral activity against hepatitis B virus (HBV).
Experimental Section
Melting points were determined using a Büchi apparatus.
All solvents were purified according to the standard
procedures. TLC was performed on plastic plates Silica Gel
60 F245 (E. Merck, layer thickness 0.2 mm). The detection
was achieved by treatment with a solution of 15% H2SO4 in
methanol, and heating at 150 oC. 1H-NMR spectra were
recorded with a Varian Gemini spectrometer at 300 MHz
with TMS as a standard. Chemical shifts were reported in δ
scale (ppm) relative to TMS as a standard, and the coupling
constants (J values) are given in Hz. EI-mass spectra were
recorded with a HP D5988 A 1000 MHz instrument
(Hewlett-Packard, Palo Alto, CA, USA). Elemental analyses
(C, H and N) were carried out at the Microanalytical Center
of Cairo University, Giza, Egypt. The elemental analyses
were found to agree favorably with the calculated values.
Silver Nanoparticles were prepared according to the publish-
ed procedures.5,22-24 2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-
α-D-glucopyranosyl chloride (2) was prepared according to
the published procedure.25
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2'-deoxy-β-D-gluco-
pyranosyl)-indoles (3a-c). A mixture of indole derivatives
(1a-c) (5 mmol) and 50% oil-immersed sodium hydride
(0.24 g, 5 mmol) in DMF (30 mL) was stirred at 70-80 oC
for 1 h and then cooled to room temperature. α-Chloro-
acetamido sugar 225 (1.83 g, 5 mmol) was added to the
mixture, and stirred at 90 oC for 3 h. The mixture was
evaporated till dryness under reduced pressure and the
residue was recrystallized from absolute ethanol to afford
3a-c.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2'-deoxy-β-D-glu-
copyranosyl) indole (3a): Yield 84%, mp 210-212 oC; 1H-
NMR (300 MHz, DMSO-d6) δ 1.75 (s, 3 H, NHCOCH3),
1.99, 2.05, 2.09 (3s, 9 H, 3 COCH3), 3.88-3.95 (m, 3 H, H-5',
H-6'), 4.50 (q, 1 H, J = 9.7 Hz, H-2'), 4.90 (d, 1 H, J = 9.0 Hz,
H-4'), 5.30 (t, 1 H, J = 9.6 Hz, H-3'), 5.66 (d, 1 H, J = 9.4 Hz,
H-1'), 7.35-7.67 (m, 7 H, NHCOCH3, Ar-H); MS m/z 446
(M+); Anal. Calcd. for C22H26N2O8: C, 59.19; H, 5.87; N,
6.27. Found: C, 59.03; H, 5.59; N, 6.07.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2'-deoxy-β-D-glu-
copyranosyl)-6-bromoindole (3b): Yield 82%, mp 264-266
oC; 1H-NMR (300 MHz, DMSO-d6) δ 1.75 (s, 3 H,
NHCOCH3), 2.05, 2.07, 2.11 (3s, 9H, 3 COCH3), 3.81-3.98
(m, 3 H, H-5', H-6'), 4.55 (m, 1 H, H-2'), 4.70-4.81 (m, 2 H,
H-3', H-4'), 5.59 (d, 1 H, J = 9.4 Hz, H-1'), 7.66-7.88 (m, 4
H, NHCOCH3, Ar-H), 8.05 (s, 1 H, H-7); MS m/z 524/526
(M+); Anal. Calcd. for C22H25BrN2O8: C, 50.30; H, 4.80; N,
5.33. Found: C, 50.13; H, 4.64; N, 5.11.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2'-deoxy-β-D-glu-
copyranosyl)-6-chloroindole (3c): Yield 80%, mp 240-242

3418 Bull. Korean Chem. Soc. 2012, Vol. 33, No. 10 Adel A.-H. Abdel-Rahman et al.
oC; 1H-NMR (300 MHz, DMSO-d6) δ 1.77 (s, 3 H,
NHCOCH3), 2.04, 2.06, 2.12 (3s, 9 H, 3 COCH3), 3.78-3.95
(m, 3 H, H-5', H-6'), 4.58 (m, 1 H, H-2'), 4.66-4.78 (m, 2 H,
H-3', H-4'), 5.60 (d, 1 H, J = 9.4 Hz, H-1'), 7.65-7.85 (m, 4
H, NHCOCH3, Ar-H), 8.06 (s, 1 H, H-7); MS m/z 480/482
(M+). Anal. Calcd. for C22H25ClN2O8: C, 54.95; H, 5.24; N,
5.83. Found: C, 54.83; H, 5.03; N, 5.60.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2'-deoxy-β-D-glu-
copyranosyl)-3-nitroindoles (4a-c). Acetyl nitrate was
generated by the dropwise addition of neat yellow 90%
HNO3 (1.35 mL, 30 mmol) to Ac2O (20 mL) which cooled
at (0 oC) followed by standing at room temperature for 10
min and was used immediately. To a stirred solution of 3a-c
(1 mmol) in Ac2O (2 mL) cooled at –70 oC was added a
solution of the acetyl nitrate dropwise via addition funnel
over 30 min. The mixture was then allowed to warm to room
temperature with stirring overnight. The reaction mixture
was poured on crushed ice and then extracted with CH2C12
(100 mL). The solvent was dried over Na2SO4, evaporated,
and coevaporated with toluene to afford a yellow solid
which was purified by recrystallization using absolute ethanol
to afford 4a-c.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2'-deoxy-β-D-glu-
copyranosyl)-3-nitroindole (4a): Yield 93%, mp 225-227
oC; 1H-NMR (300 MHz, DMSO-d6) δ 1.77 (s, 3 H,
NHCOCH3), 2.06, 2.08, 2.12 (3s, 9H, 3 COCH3), 3.34-3.49
(m, 2 H, H-6'), 3.69-3.75 (m, 2 H, H-4', H-5'), 3.96-4.12 (m,
1 H, H-3'), 4.18-4.29 (m, 1 H, H-2'), 5.78 (s, 1 H, H-1'),
7.35-7.67 (m, 5 H, NHCOCH3, Ar-H), 7.88 (s, 1 H, H-2);
MS m/z 491 (M+). Anal. Calcd. for C22H25N3O10: C, 53.77;
H, 5.13; N, 8.55. Found: C, 53.60; H, 5.01; N, 8.32.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2'-deoxy-β-D-glu-
copyranosyl)-6-bromo-3-nitroindole (4b): Yiel d 95%, m p
209-211 oC; 1H-NMR (300 MHz, DMSO-d6) δ 1.76 (s, 3 H,
NHCOCH3), 2.06, 2.08, 2.10 (3s, 9H, 3 COCH3), 3.28-3.39
(m, 2 H, H-6'), 3.54-3.59 (m, 2 H, H-4', H-5'), 3.87 (m, 1 H,
H-3'), 4.12 (m, 1 H, H-2'), 5.49 (s, 1 H, H-1'), 7.66-7.88 (m,
3 H, NHCOCH3, Ar-H), 7.92 (s, 1 H, H-2), 8.05 (s, 1 H, H-
7); MS m/z 569/571 (M+). Anal. Calcd. for C22H24BrN3O10:
C, 46.33; H, 4.24; N, 7.37. Found: C, 46.11; H, 4.09; N, 7.10.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2'-deoxy-β-D-glu-
copyranosyl)-6-chloro-3-nitroindole (4c): Yield 9 0%, m p
233-235 oC; 1H-NMR (300 MHz, DMSO-d6) δ 1.74 (s, 3 H,
NHCOCH3), 2.06, 2.08, 2.13 (3s, 9H, 3 COCH3), 3.28-3.39
(m, 2 H, H-6'), 3.58-3.63 (m, 2 H, H-4', H-5'), 3.89 (m, 1 H,
H-3'), 4.15 (m, 1 H, H-2'), 5.53 (s, 1 H, H-1'), 7.65-7.85 (m,
3 H, NHCOCH3, Ar-H), 7.98 (s, 1 H, H-2), 8.06 (s, 1 H, H-
7); MS m/z 525/527 (M+). Anal. Calcd. for C22H24ClN3O10:
C, 50.25; H, 4.60; N, 7.99. Found: C, 50.05; H, 4.40; N,
7.77.
Procedure for the Reduction of Nitro-Compounds using
Solid Silver as Catalyst, SNSM to Afford 1-(2'-Acetamido-
β-D-glucopyranosyl)-3-aminoindoles (5a-c).
Step (i): Compounds 4a-c (0.5 mmol) in a stirred mixture
of methanol (5 mL) and ammonium hydroxide (25%) (5
mL) were stirred at room temperature for 2 h. The resulting
solution was evaporated till dryness under reduced pressure.
Ste p (i i): In a standard quartz cuvette having a 1-cm path
length, 2 mL of water and 20 μL of nitrocompounds
(resulting from step i) (final concentration in solution: 4.3 ×
10−4 M) were taken. To it was added 300 μL of aqueous
NaBH4 (0.1 M). It took 5 min for the peak of the colorless
product to appear (induction time, IT) in the blue region
after the addition of (0.0053 g) solid silica gel impregnated
silver catalyst, SNSM.6 Then the gradual decoloration of the
yellow solution (due to nitrocompounds) and the formation
of the product were observed through UV–visible spectro-
photometry (Fig. 1). After the yellow color was completely
discharged, i.e., the completed reaction was, the peak due to
nitrocompounds was no longer observed. On the other hand,
the appearance of a new peak at 430 nm was noticed 5 min
after of the completion of the reaction. The solvent was
evaporated under reduced pressure and the residue was
dissolved in absolute ethanol and left at room temperature
for overnight to afford 5a-c as a pale yellow crystals.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2-deoxy-β-D-glu-
copyranosyl)-3-aminoindole (5a): Yield 93%, mp 217-219
oC; 1H-NMR (300 MHz, DMSO-d6) δ 1.71 (s, 3 H,
NHCOCH3), 3.22-3.38 (m, 2 H, H-6), 3.62-3.79 (m, 2 H, H-
4, H-5), 3.85-3.89 (m, 1 H, H-3), 4.12-4.22 (m, 1 H, H-2),
5.37-5.42 (m, 3 H, 3 OH), 5.69 (s, 1 H, H-1), 6.27 (s, 1H,
NH2), 7.12-7.51 (m, 5 H, NHCOCH3, Ar-H); MS m/z 335
(M+). Anal. Calcd. for C16H21N3O5: C, 57.30; H, 6.31; N,
12.53. Found: C, 57.11; H, 6.16; N, 12.34.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2'-deoxy-β-D-glu-
copyranosyl)-3-amino-6-bromoindole (5b): Yield 90%,
mp 270-272 oC; 1H-NMR (300 MHz, DMSO-d6) δ 1.68 (s, 3
H, NHCOCH3), 3.22-3.32 (m, 2 H, H-6'), 3.45-3.54 (m, 2 H,
H-4', H-5'), 3.80-3.95 (m, 1 H, H-3'), 4.19-4.23 (m, 1 H, H-
2'), 5.35-5.45 (m, 3 H, 3 OH), 5.69 (s, 1 H, H-1'), 6.25 (s,
1H, NH2), 7.19 (s, 1H, H-2), 7.75-7.99 (m, 3 H, NHCOCH3,
Ar-H), 8.52 (s, 1 H, H-8); MS m/z 413/415 (M+). Anal.
Calcd. for C16H20BrN3O5: C, 46.39; H, 4.87; N, 10.14. Found:
C, 46.22; H, 4.60; N, 10.00.
1-(2'-Acetamido-3',4',6'-tri-O-acetyl-2-deoxy-β-D-glu-
copyranosyl)-3-amino-6-chloroindole (5c): Yield 90%,
Figure 1. UV-visible spectra for the successive reduction of 3-
Aminoindoles by SNSM as catalyst.

Synthesis and Antiviral Activity of 3-Aminoindole Nucleosides Bull. Korean Chem. Soc. 2012, Vol. 33, No. 10 3419
mp 248-250 oC; 1H-NMR (300 MHz, DMSO-d6) δ 1.75 (s, 3
H, NHCOCH3), 3.28-3.39 (m, 2 H, H-6'), 3.60-3.77 (m, 2 H,
H-4', H-5'), 3.84 (m, 1 H, H-3'), 4.18 (m, 1 H, H-2'), 5.35-
5.39 (m, 3 H, 3 OH), 5.69 (s, 1 H, H-1'), 6.29 (s, 1H, NH2),
7.17 (s, 1 H, H-2), 7.38-7.69 (m, 4 H, NHCOCH3, Ar-H);
MS m/z 369/371 (M+). Anal. Calcd. for C16H20ClN3O5: C,
51.97; H, 5.45; N, 11.36. Found: C, 51.82; H, 5.31; N, 11.22.
1-(2'-Acetamido-β-D-glucopyranosyl)-3-nitro-6-substitutes
amino-indoles (6-11). A solution of 4b (0.570 g, 1 mmoL)
and an excess of the appropriate amine was stirred under
reflux for 2 h. The solvent was removed in vacuo and the
residue was recrystallized from ethanol to give 6-11.
1-(2'-Acetamido-β-D-glucopyranosyl)-6-methylamino-
3-nitroindole (6): Yield 78%, mp 280-282 oC; 1H-NMR
(300 MHz, DMSO-d6) δ 1.76 (s, 3 H, NHCOCH3), 2.65 (s, 3
H, NHCH3), 3.30-3.43 (m, 2 H, H-6'), 3.55-3.65 (m, 2 H, H-
4', H-5'), 3.89-3.99 (m, 1 H, H-3'), 4.16 (m, 1 H, H-2'), 5.19-
5.27 (m, 3 H, 3 OH), 5.51 (s, 1 H, H-1'), 6.09-6.26 (m, 2 H,
H-5, H-7), 7.05 (m, 1 H, NHCH3), 7.80-7.88 (m, 3 H,
NHCOCH3, H-2, H-4); MS m/z 394 (M+). Anal. Calcd. for
C17H22N4O7: C, 51.77; H, 5.62; N, 14.21. Found: C, 51.60;
H, 5.39; N, 14.07.
1-(2'-Acetamido-β-D-glucopyranosyl)-6-ethylamino-3-
nitroindole (7): Yield 80%, mp 243-245 oC; 1H-NMR (300
MHz, DMSO-d6) δ 1.11 (t, 3 H, J = 7.1 Hz, CH3), 1.89 (s, 3
H, NHCOCH3), 3.35-3.45 (m, 4 H, H-6', NHCH2), 3.64-3.75
(m, 2 H, H-4', H-5'), 3.99 (m, 1 H, H-3'), 4.23 (m, 1 H, H-2'),
5.31-5.37 (m, 3 H, 3 OH), 5.73 (s, 1 H, H-1'), 6.06-6.25 (m,
2 H, H-5, H-7), 6.98 (m, 1 H, NHCH2), 7.78-7.89 (m, 3 H,
NHCOCH3, H-2, H-4); MS m/z 408 (M+). Anal. Calcd. for
C18H24N4O7: C, 52.94; H, 5.92; N, 13.72. Found: C, 52.66;
H, 5.78; N, 13.66.
1-(2'-Acetamido-β-D-glucopyranosyl)-3-nitro-6-propyl-
aminoindole (8): Yield 79%, mp 270-272 oC; 1H-NMR
(300 MHz, DMSO-d6) δ 0.89 (t, 3 H, J = 7.1 Hz, CH3), 1.36
(m, 2 H, CH2), 1.75 (s, 3 H, NHCOCH3), 3.22-3.40 (m, 4 H,
H-6', NHCH2), 3.62-3.78 (m, 2 H, H-4', H-5'), 3.85-3.93 (m,
1 H, H-3'), 4.12-4.28 (m, 1 H, H-2'), 5.37-5.48 (m, 3 H, 3
OH), 5.71 (s, 1 H, H-1'), 6.07-6.18 (m, 2 H, H-5, H-7), 7.21
(m, 1 H, NHCH2), 7.75-7.88 (m, 3 H, NHCOCH3, H-2, H-
4); MS m/z 422 (M+). Anal. Calcd. for C19H26N4O7: C,
54.02; H, 6.20; N, 13.26. Found: C, 53.90; H, 6.10; N, 13.10.
1-(2-Acetamido-β-D-glucopyranosyl)-6-benzylamino-3-
nitroindole (9): Yield 85%, mp 223-225 oC; 1H-NMR (300
MHz, DMSO-d6) δ 1.68 (s, 3 H, NHCOCH3), 3.22-3.36 (m,
2 H, H-6'), 3.45-3.59 (m, 2 H, H-4', H-5'), 3.80-3.97 (m, 1 H,
H-3'), 4.19-4.25 (m, 1 H, H-2'), 4.49 (s, 2 H, CH2), 5.35-5.48
(m, 3 H, 3 OH), 5.74 (s, 1 H, H-1'), 7.19-7.35 (m, 8 H,
NHCH2, Ar-H), 7.74-7.81 (m, 3 H, NHCOCH3, H-2, H-4);
MS m/z 470 (M+). Anal. Calcd. for C23H26N4O7: C, 58.72; H,
5.57; N, 11.91. Found: C, 58.60; H, 5.31; N, 11.67.
1-(2'-Acetamido-β-D-glucopyranosyl)-3-nitro-6-pyrro-
lidinoindole (10): Yield 83%, mp 209-211 oC; 1H-NMR
(300 MHz, DMSO-d6) δ 1.26-1.38 (m, 4 H, 2 x CH2), 1.76
(s, 3 H, NHCOCH3), 3.28-3.41 (m, 6 H, H-6', 2 x NCH2),
3.60-3.79 (m, 2 H, H-4', H-5'), 3.85 (m, 1 H, H-3'), 4.19 (m,
1 H, H-2'), 5.33-5.41 (m, 3 H, 3 OH), 5.66 (s, 1 H, H-1'), 6.09-
6.28 (m, 2 H, H-5, H-7), 7.72-7.83 (m, 3 H, NHCOCH3, H-
2, H-4); MS m/z 434 (M+). Anal. Calcd. for C20H26N4O7: C,
55.29; H, 6.03; N, 12.90. Found: C, 55.20; H, 5.90; N, 12.78.
1-(2'-Acetamido-β-D-glucopyranosyl)-6-morpholino-3-
nitroindole (11): Yield 84%, mp 221-223 oC; 1H-NMR (300
MHz, DMSO-d6) δ 1.74 (s, 3 H, NHCOCH3), 3.24-3.36 (m,
6 H, H-6', 2 x NCH2), 3.53-3.68 (m, 6 H, H-4', H-5', 2 x
OCH2), 4.15-4.27 (m, 1 H, H-3'), 4.30-4.43 (m, 1 H, H-2'),
5.25-5.36 (m, 3 H, 3 OH), 5.64 (s, 1 H, H-1'), 6.04-6.23 (m,
2 H, H-5, H-7), 7.75-7.80 (m, 3 H, NHCOCH3, H-2, H-4);
MS m/z 450 (M+). Anal. Calcd. for C20H26N4O8: C, 53.33; H,
5.82; N, 12.44. Found: C, 53.22; H, 5.70; N, 12.22.
Procedure for the Reduction of Nitro-Compounds using
Solid Silver as Catalyst, SNSM to Afford 1-(2'-Acetamido-
β-D-glucopyranosyl)-3-amino-6-substituted aminoindoles
(12-17). Compounds 12-17 were prepared according to step
(ii) as mentioned in the preparation of 5a-c.
1-(2-Acetamido-β-D-glucopyranosyl)-3-amino-6-methyl-
aminoindole (12): Yield 93%, mp 247-249 oC; 1H-NMR
(300 MHz, DMSO-d6) δ 1.74 (s, 3 H, NHCOCH3), 2.68 (s, 3
H, NHCH3), 3.34-3.45 (m, 2 H, H-6'), 3.56-3.68 (m, 2 H, H-
4', H-5'), 3.85-3.93 (m, 1 H, H-3'), 4.17 (m, 1 H, H-2'), 5.15-
5.29 (m, 3 H, 3 OH), 5.53 (s, 1 H, H-1'), 6.15-6.40 (m, 4H,
H-5, H-7, NH2) 7.05-7.19 (m, 2 H, NHCH3, H-2), 7.80-7.83
(m, 2 H, NHCOCH3, H-4); MS m/z 364 (M+). Anal. Calcd.
for C17H24N4O5: C, 56.03; H, 6.64; N, 15.38. Found: C,
55.86; H, 6.52; N, 15.22.
1-(2'-Acetamido-β-D-glucopyranosyl)-3-amino-6-ethyl-
aminoindole (13): Yield 92%, mp 217-219 oC; 1H-NMR
(300 MHz, DMSO-d6) δ 1.13 (t, 3 H, J = 7.1 Hz, CH3), 1.84
(s, 3 H, NHCOCH3), 3.35-3.42 (m, 4 H, H-6', NHCH2),
3.60-3.71 (m, 2 H, H-4', H-5'), 3.90 (m, 1 H, H-3'), 4.20 (m,
1 H, H-2'), 5.31-5.39 (m, 3 H, 3 OH), 5.78 (s, 1 H, H-1'),
6.11-6.37 (m, 4H, H-5, H-7, NH2) 7.08-7.22 (m, 2 H, NHCH3,
H-2), 7.78-7.89 (m, 2 H, NHCOCH3, H-4); MS m/z 378
(M+). Anal. Calcd. for C18H26N4O5: C, 57.13; H, 6.93; N,
14.81. Found: C, 57.00; H, 6.82; N, 14.62.
1-(2'-Acetamido-β-D-glucopyranosyl)-3-amino-6-prop-
ylaminoindole (14): Yield 91%, mp 233-235 oC; 1H-NMR
(300 MHz, DMSO-d6) δ 0.87 (t, 3 H, J = 7.1 Hz, CH3), 1.34
(m, 2 H, CH2), 1.71 (s, 3 H, NHCOCH3), 3.25-3.41 (m, 4 H,
H-6', NHCH2), 3.60-3.83 (m, 2 H, H-4', H-5'), 3.88-3.99 (m,
1 H, H-3'), 4.10-4.25 (m, 1 H, H-2'), 5.34-5.45 (m, 3 H, 3
OH), 5.73 (s, 1 H, H-1'), 6.15-6.40 (m, 4H, H-5, H-7, NH2)
7.05-7.23 (m, 2 H, NHCH2, H-2), 7.80-7.83 (m, 2 H,
NHCOCH3, H-4); MS m/z 392 (M+). Anal. Calcd. for
C19H28N4O5: C, 58.15; H, 7.19; N, 14.28. Found: C, 58.00;
H, 7.04; N, 14.11.
1-(2'-Acetamido-β-D-glucopyranosyl)-3-amino-6-benz-
ylaminoindole (15): Yield 94%, mp 212-214 oC; 1H-NMR
(300 MHz, DMSO-d6) δ 1.71 (s, 3 H, NHCOCH3), 3.24-
3.38 (m, 2 H, H-6'), 3.43-3.58 (m, 2 H, H-4', H-5'), 3.79-3.99
(m, 1 H, H-3'), 4.17-4.24 (m, 1 H, H-2'), 4.45 (s, 2 H, CH2),
5.35-5.45 (m, 3 H, 3 OH), 5.74 (s, 1 H, H-1'), 6.15-6.40 (m,
4H, H-5, H-7, NH2) 7.11-7.26 (m, 7 H, NHCH2, H-2, Ar-H),
7.80-7.83 (m, 2 H, NHCOCH3, H-4); MS m/z 440 (M+).
Anal. Calcd. for C23H28N4O5: C, 62.71; H, 6.41; N, 12.72.

3420 Bull. Korean Chem. Soc. 2012, Vol. 33, No. 10 Adel A.-H. Abdel-Rahman et al.
Found: C, 62.50; H, 6.30; N, 12.60.
1-(2'-Acetamido-β-D-glucopyranosyl)-3-amino-6-pyrro-
lidinoindole (16): Yield 93%, mp 244-246 oC; 1H-NMR
(300 MHz, DMSO-d6) δ 1.26-1.35 (m, 4 H, 2 x CH2), 1.75
(s, 3 H, NHCOCH3), 3.28-3.45 (m, 6 H, H-6', 2 x NCH2),
3.55-3.75 (m, 2 H, H-4', H-5'), 3.83 (m, 1 H, H-3'), 4.21 (m,
1 H, H-2'), 5.33-5.44 (m, 3 H, 3 OH), 5.65 (s, 1 H, H-1'),
6.15-6.37 (m, 4H, H-5, H-7, NH2), 7.05-7.15 (m, 1 H, H-2),
7.77-7.87 (m, 2 H, NHCOCH3, H-4); MS m/z 404 (M+).
Anal. Calcd. for C20H28N4O5: C, 59.39; H, 6.98; N, 13.85.
Found: C, 59.12; H, 6.72; N, 13.66.
1-(2'-Acetamido-β-D-glucopyranosyl)-3-amino-6-morpho-
linoindole (17): Yield 94%, mp 210-212 oC; 1H-NMR (300
MHz, DMSO-d6) δ 1.70 (s, 3 H, NHCOCH3), 3.24-3.30 (m,
6 H, H-6', 2 x NCH2), 3.50-3.65 (m, 6 H, H-4', H-5', 2 x
OCH2), 4.15-4.25 (m, 1 H, H-3'), 4.30-4.45 (m, 1 H, H-2'),
5.25-5.35 (m, 3 H, 3 OH), 5.65 (s, 1 H, H-1'), 6.11-6.33 (m,
4H, H-5, H-7, NH2) 7.03-7.18 (m, 2 H, NHCH3, H-2), 7.75-
7.87 (m, 2 H, NHCOCH3, H-4); MS m/z 420 (M+). Anal.
Calcd. for C20H28N4O6: C, 57.13; H, 6.71; N, 13.33. Found:
C, 57.02; H, 6.60; N, 13.21.
Antiviral Testing
The HepG2.2.2.15 cell line, supplied by State Serum
Institute, Denmark, was maintained in RPMI-1640 Glutamax,
Gibco BRL Life technologies.26,27 The standard drug Lami-
vudine was from GlaxoSmithKline. The cell line was main-
tained in RPMI-1640 (Glutamax) culture medium contain-
ing 100 IU/mL nystatin, 380 µg/mL G418 (genetecin) and
10% fetal calf serum (FCS) (Gibco BRL Life Technologies).
The transferred HEPG2.2.2.15 cells were kept in a tissue
culture flask at 37 oC and 5% CO2. Subcultures were set up
after a week by trypsination (10% versin/trypsin (Biochrome
KG) and transferred to a 96-well tissue culture plate. 5-Fold
serial dilutions of tested compounds with final concent-
rations ranging from 100 to 0.03 µM were added to the cell
suspension and incubated for 6 d at 37 oC and 5% CO2. Each
compound was tested in triplicate. Cells with no compounds
added to their culture were used for comprison (blank cells).
DNA Extraction. DNA extraction was done by incubat-
ing 10 µL of diluted supernatant with 10 µL of 0.2 M NaOH
at 37 ºC for 1 h, then carefully adding 9.6 µL of 0.2M HCl
followed by addition of 90 µL of Tris–EDTA buffer [(2-
amino-2-(hydroxymethyl)-1,3-propanediol–EDTA) (Gibco
BRL Life Technologies)].
PCR-ELISA Detection of HBV DNA. The DNA content
in the cell culture supernatant was determined by polymer-
ase chain reaction amplification of the HBV DNA using 1
µmol/L of each of the following primers: HCID-1 primer
(5'-GGAAAGAAGTCAGAAGGCA-3') and HCID-2 primer
(5'-TTGGGGGAGGAGATTAGGTT-3'), in a reaction mix-
ture containing 14 µL extracted supernatant, 4 mmol/L
MgCl2, 10 µmol/L DIG-11-dUTP (Roche, Germany), 190
µmol/L dTTP, 200 µmol/L dATP, dGTP, dCTP (Roche)
1.5 U Taq polymerase (Roche), in a total volume 50 µL.
PCR reaction conditions were: 32 cycles of 10 min at 94 ºC,
30 s at 58 ºC, and 30 s at 72 ºC with a 3 s increment for each
cycle in a Perkin Elmer 480 thermal cycler (Perkin Elmer,
USA). The PCR product was detected by DIG-ELISA assay
(Roche). The optical density from DNA of the test compound
was compared to that of the blank culture.28,29
Cytotoxicity Assay. 3-(3,5-Dimethylthiazole-2-yl)-2,5-
diphenyltetrazolium bromide (Sigma, USA) is a colorless
substrate that is transformed to a colored product by living
cells, but not by dead cells. The assay utilizes this compound
to test for the viability of the cells with the test compound
added compared to the viability of the blank cells.30
Results and Discussion
The ease of accessibility and the biological significance of
2-acetamido-2-deoxy-D-glucose31-33 have prompted us to
use this aminosugar as a starting material in Sasaki glycos-
ylation reaction.34 Thus, the sodium salt of indole derivatives
1a-c was condensed with 2-acetamido-1-chloro-3,4,6-tri-O-
acetyl-2-deoxy-D-glucose (2)25 in dry DMF. The reaction
was proceeded at 90 oC to give the desired 1-(2'-acetamido-
3',4',6'-tri-O-acetyl-2'-deoxy-β-D-glucopyranosyl)indoles
(3a-c) (Scheme 1).
The structure of the nucleosides 3a-c was determined on
the basis of its respective 1H-NMR, mass spectra and micro-
analyses, which was found to be consistent with the assigned
structure by comparison with the structures of glycopyrano-
side analogues.35-37 The 1H-NMR spectrum of 3a-c showed
the anomeric proton peaks at δ 5.59-5.66 ppm as a doublet
with J1',2' coupling constant of 9.4 Hz. Coupling constant of
9.4 Hz in sugar moieties normally results from the diaxial
orientation of H-1' and H-2' protons, which is clearly indi-
cative of the β-configuration of the products.35-37 The methyl
protons of the acetamido group (NHCOCH3) appeared as
singlet at δ 1.75-1.77 ppm, while the other three acetyl
groups appeared as singlet at δ 1.99-2.12, respectively.
Nitration of 3a-c using acetic anhydride-nitric acid mix-
ture afforded the corresponding 3-nitroindole nucleoside
derivatives 4a-c. The 1H-NMR spectra showed a singlet at δ
7.88-7.98 ppm corresponding to H-2. Treatment of 4a-c with
ammonium hydroxide (25%) in methanol at room temper-
Scheme 1. Synthesis of nucleosides 3-5.

Synthesis and Antiviral Activity of 3-Aminoindole Nucleosides Bull. Korean Chem. Soc. 2012, Vol. 33, No. 10 3421
ature resulted in the aminolysis of three acetyl groups and
the nitro group of the crude intermediates were reduced
directly by solid silica gel impregnated silver catalyst (SNSM)
to afford the corresponding amino indole nucleosides 5a-c.
Treatement of 4b with different primary and secondary
amines at reflux temperature afforded the corresponding 3-
nitro-6-substituted aminoindoles 6-11, respectively. Reduction
of the 3-nitro group again by solid silica gel impregnated
silver catalyst (SNSM) provided the new amino indole
nucleosides 12-17.
The compounds were tested for their antiviral activity and
cytotoxicity against HBV using the HepG2.2.2.15 cell line, a
human hepatoma cell line producing HBV viral particles.26,27
The drug Lamivudine (4-amino-1-[(2R,5S)-2-(hydroxy-
methyl)-1,3-oxathiolan-5-yl]pyrimidin-2(1H)-one), a potent
selective inhibitor of HBV replication,28 has been used as a
standard positive control. The 50% inhibitory concentration
(IC50) of an antiviral drug was determined by plotting the
DNA content in the cell culture supernatant versus the
concentration of the test compound. The 50% cytotoxic
effect (CC50) was calculated from the average viability of the
cells in proportion to the concentration of the drug; for all
the tested compounds its value was 100 μM. The selectivity
index (SI) was calculated as CC50/IC50.29,30 The results of the
antiviral activity measurements against HBV are shown in
the Table 1. Preliminary screening indicated that compound
6 and 16 showed the highest inhibitory activity against HBV
among this series of tested compounds with low cytotoxicity
and a selectivity index of 2500.0 followed by compounds 3c,
5a, 5c and 17. Compounds 4a-c, 5b, 8, 10, 11 and 14 showed
moderate inhibition with moderate cytotoxicity while the
other tested compounds exhibited less activity against HBV.
Conclusions
In conclusion, a new and versatile approach to the syn-
thesis of 3-aminoindole nucleosides of 2-acetamido-2-de-
oxy-D-glucose was established. The use of modified hetero-
cyclic base in nucleoside synthesis as well as the convenient
experimental conditions merits the efficiency of this ap-
proach.
References
1. Kundu, S.; Ghosh, S. K.; Mandal, M.; Pal, T. New J. Chem. 2003,
27, 656.
2. Jana, N. R.; Pal, T. Langmuir 1999, 15, 3458.
3. Jana, N. R.; Sau, T. K.; Pal, T. J. Phys. Chem. B 1999, 103, 115.
4. Kundu, S.; Ghosh, S. K.; Mandal, M.; Pal, T. New J. Chem. 2002,
26, 1081.
5. Pal, T.; Jana, N. R.; Pal, A.; Creighton, J. A.; Beezer, A. E. J.
Indian Chem. Soc. 2000, 77, 34.
6. d’Ischia, M.; Napolitano, A.; Pezzella, A. In Comprehensive
Heterocyclic Chemistry III; Katritzky, A. R., Ramsden, C. A.,
Scriven, E. F. V., Taylor, R. J. K., Eds.; Elsevier: Oxford, 2008;
Vol. 3, Chapter 3.04, p 353.
7. Chang, R.; Marco, D. I.; Kuduk, S. WO Patent 042092/2009,
Chem. Abstr. 2009, 150, 374291.
8. Bahekar, R. H.; Jain, M. R.; Goel, A.; Patel, D. N.; Prajapati, V.
M.; Gupta, A. A.; Jadav, P. A.; Patel, P. R. Bioorg. Med. Chem.
2007, 15, 3248.
9. Kesteleyn, B. R. R.; Raboisson, P. J.-M.; Surleraux, D. L. N. G.;
Hache, G. Y. P.; Vendeville, S. M. H.; Peeters, A. A.; Wigerink, P.
T. B . P. WO Patent 111047/2005, Chem. Abstr. 2006, 144, 6779.
10. Zhang, Z.; Wang, S.; Wan, S.; Ren, S.; Li, W.; Jiang, T. Carbohydr.
Res. 2009, 344, 291.
11. Romagnoli, R.; Baraldi, P. G.; Sarkar, T.; Carrion, M. D.; Cara, C.
L.; Cruz-Lopez, O.; Preti, D.; Tabrizi, M. A.; Tolomeo, M.; Grimaudo,
S.; Di Christina, A.; Zonta, N.; Balzarini, J.; Brancale, A.; Hseih,
H.-P.; Hamel, E. J. Med. Chem. 2008, 51, 1464.
12. Rádl, S.; Hezky´, P.; Urbánková, J.; Váchal, P.; Krej í, I. Coll.
Czech. Chem. Commun. 2000, 65, 280.
13. Lehmann, F.; Haile, S.; Axen, E.; Medina, C.; Uppenberg, J.;
Svensson, S.; Lundbaeck, T.; Rondahl, L.; Barf, T. Bioorg. Med.
Chem. Lett. 2004, 14, 4445.
14. Roy, S.; Gribble, G. W. Heterocycles 2006, 70, 51.
15. Hooper, M. K.; Utsunomiya, M.; Hartwig, J. F. J. Org. Chem.
2003, 68, 2861.
16. Simakov, S. V.; Velezheva, V. S.; Kozik, T. A.; Ershova, Y. A.;
Chernov, V. A.; Suvorov, N. N. Pharm. Chem. J. 1983, 17, 707.
17. Suvorov, N. N.; Velezheva, V. S.; Yarosh, A. V.; Erofeev, Y. V.;
Kozik, T. N. Chem. Heterocycl. Compd. 1975, 11, 959.
18. Velezheva, V. S.; Gunar, G. N.; Balyakina, M. A.; Suvorov, N. N.
Chem. Heterocycl. Compd. 1978, 14, 757.
19. Przhevalskii, N. M.; Skvortsova, N. S.; Magedov, I. V. Chem.
Heterocycl. Compd. 2002, 38, 1055.
20. Garcia, E. E.; Benjamin, L.; Fryer, R. I. J. Heterocycl. Chem.
c
ê
Scheme 2. Synthesis of compounds 6-17.
Table 1. Cytotoxic effect (CC50)a and inhibitory concentration
(IC50) of newly synthesized compounds
Compd HBV DNA
IC50 [µM]
Hep2.2.2.15
CC50 [µM] Compd HBV DNA
IC50 [µM]
Hep2.2.2.15
CC50 [µM]
Lamivudine 0.1 1000.0 70.9 111.1
3a 1.3 76.9 80.5 200.0
3b 1.4 71.4 90.8 156.2
3c 0.3 333.3 10 0.5 200.0
4a 0.5 200.0 11 0.4 250.0
4b 0.5 200.0 12 0.9 111.1
4c 0.4 250.0 13 0.8 156.2
5a 0.3 333.3 14 0.4 250.0
5b 0.4 250.0 15 1.4 71.4
5c 0.3 333.3 16 0.2 500.0
60.2 500.0 17 0.3 333.3
aCytotoxic effect (CC50) of all tested compounds is 100 µM.

3422 Bull. Korean Chem. Soc. 2012, Vol. 33, No. 10 Adel A.-H. Abdel-Rahman et al.
1973, 10, 51.
21. Abdel-Rahman, A. A.-H.; El-Sayed, W. A.; Abdel-Bary, H. M.;
Abdel-Megied, A. E.-S.; Morcy, E. M. I. Monatsh. Chem. 2008,
139, 1095.
22. Pradhan, N.; Pal, A.; Pal, T. Colloids and Surfaces A 2002, 196,
247.
23. Liu, P.; Zhao, M. Applied Surface Sci. 2009, 255, 3989.
24. Kiasat, A. R.; Mirzajani, R.; Ataeian, F.; Fallah-Mehrjardi, M.
Chinese Chem. Lett. 2010, 21, 1015.
25. Horton, D. Methods in Carbohydr. Chem. 1964, Vo l . V I, 282.
26. Schwyzer, R.; Kappeler, H. Helv. Chim. Acta 1961, 44, 1991.
27. Sells, M. A.; Zelent, A. Z.; Shvartsman, M.; Acs, G. J. Virol. 1988,
62, 2836.
28. Korba, B. E.; Gerin, J. L. Antiviral Res. 1992, 19, 55.
29. Doong, S. L.; Tsai, C. H.; Chinazi, R. F.; Liotta, D. C.; Cheng, Y.
C. Proc. Nat. Acad. Sci. USA 1991, 88, 4895.
30. Fouad, T.; Nielsen, C.; Brunn, L.; Pederson, E. B. Sc. J. Az. Med.
Fac. (GIRLS) 1998, 19, 1173.
31. Coffy, S. Rodds, Chemistry of Carbon Compounds, Aliphatic
Compounds 1976, Vol . 1 , Part F, p. 483, Elsevier, Amsterdam.
32. Marten, D. W.; Mayer, P. A.; Rodwell, V. W.; Granner, D. K.
Harpers, Reviews of Biochemistry; 1985, 20th. ed. Lang Medical
Publication, CA p. 150.
33. Strange, R. E.; Powell, J. F. Biochem. J. 1954, 58, 80.
34. Sasaki, T.; Minamoto, K.; Suzuki, T.; Yamashita, S. Tetrahedron
1980, 36, 865.
35. Abdel-Rahman, A. A.-H. Pharmazie 2001, 56, 773.
36. Al-Masoudi, N. A.; Pfleiderer, W. Tet r a h e d r o n 1993, 49, 7579.
37. Al-Masoudi, N. A.; Issa, F. B. Acta Chem. Scand. 1997, 51, 958.