Design and synthesis of some new theophylline derivatives with bronchodilator and antibacterial activities

Article abstract of DOI:10.1007/s12272-011-0101-8

Methylxanthines especially theophylline have been recognized as potent bronchodilators for the relief of acute asthma for over 65 years. Recently, it was found that bacterial infection plays a role in asthma pathogenesis. Accordingly, the present work inv

Full text of DOI:10.1007/s12272-011-0101-8

Arch Pharm Res Vol 34, No 1, 3-21, 2011
DOI 10.1007/s12272-011-0101-8
Design and Synthesis of Some New Theophylline Derivatives with
Bronchodilator and Antibacterial Activities
Alaa M. Hayallah, Walid A. Elgaher, Ola I. Salem, and Abdel Alim M. Abdel Alim
Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt
(Received May 6, 2010/Revised June 28, 2010/Accepted Jnue 30, 2010)
Methylxanthines especially theophylline have been recognized as potent bronchodilators for
the relief of acute asthma for over 65 years. Recently, it was found that bacterial infection
plays a role in asthma pathogenesis. Accordingly, the present work involves the synthesis of
6-(4-(un)substituted phenyl)thiazolo[2,3-f]theophyllines 2a-g and different series of 8-(1,2,4-
triazol-3-ylmethylthio)theophyllines 6-9. The chemical structures of the target compounds
were proved by IR, 1H NMR, 13C NMR, EI-MS and HRMS spectroscopic techniques along with
elemental analyses. The bronchodilator activity of fifteen compounds was determined in vivo
by acetylcholine induced bronchospasm in anaesthetized guinea pigs. Results revealed that all
compounds showed moderate to good activity; in addition, five compounds exhibited a bron-
chodilator activity nearly similar to that of aminophylline as a standard. The antibacterial
activity of all the target compounds was investigated in vitro against both Gram-positive and
Gram-negative bacterial strains. Results revealed that some compounds showed more potent
antibacterial activity than ampicillin as a standard. Acute toxicity study for four target com-
pounds revealed that none of these derivatives showed significant toxicity up to 300 mg/kg. It
was found that compound 8c combined both promising bronchodilator and antibacterial acti-
vities. This compound could be subjected for further investigations as a new possible candi-
date in the treatment of bronchial asthma.
Key words: Xanthine derivatives, Asthma, Bronchodilators, Antibacterial activity, Acute to-
xicity
asthmatic patients might also have increased suscep-
tibility to bacterial infections. Several studies of both
INTRODUCTION
Asthma is a global health problem and its incidence chronic and acute asthma using macrolide (roxithro-
is expected to increase throughout the world over the mycin, clarithromycin) (Black et al , 2001; Kraft et al
next decade, particularly, in the developing countries 2002), or ketolide (telithromycin) (Johnston et al , 2006)
(Baraldi et al , 2007). The role of infection in asthma antibiotics proved that these antibiotics do have a
.
.,
.
.
is complex and still not fully understood, however beneficial effect in treating asthma (Black, 2007). The
there is an increasing evidence that respiratory tract reported adverse effects of theophylline are nausea,
infections have been implicated in the pathogenesis vomiting, tachycardia, insomnia, and narrow thera-
of asthma (Hahn et al
.
, 1991; Cook et al
., 1998; peutic index (Ellis et al., 2007). Accordingly, search for
Cunningham et al , 1998; Kraft et al
.
., 1998; Johnston new compounds embracing both antibacterial and anti-
and Martin, 2005). Moreover, it has, recently, been re- asthmatic effects still represent a goal and a challenge
ported that asthma is a risk factor for invasive pneu- facing both medicinal chemists and physicians.
mococcal disease (Talbot et al
.
, 2005), suggesting that
It was reported that alkyl substitution at the 8-
position of methylxanthines yielded compounds more
active than theophylline on tracheal relaxation in
guinea pigs (Karlsson et al
., 1982). Several 8-substi-
tuted theophylline derivatives were synthesized, and
showed a potent bronchodilator activity (Regnier et
Correspondence to: Alaa A. K. M. Hayallah, Department of
Pharmaceutical Organic Chemistry, Faculty of Pharmacy, Assiut
University, Assiut 71526, Egypt
Tel: 0020183410110, Fax: 0020882332776
E-mail: alaa_hayalah@yahoo.com
3

4
A. M. Hayallah et al.
Fig. 1. 8-Heterocyclyl-xanthine derivatives as bronchodilators
al.
, 1987; Baziard-Mouysset et al
.
, 1995; Berk et al
.,
(λ
= 254 nm). All chemical yields are unoptimized and
2005). Recently, 8-heterocyclyl-xanthine derivative generally represent the result of a single experiment.
CVT-6883 (Fig. 1) is in Phase I clinical trials as an IR spectra were recorded on a Shimadzu spectrophoto-
antiasthmatic agent (Baraldi et al , 2007). In addition, meter (IR-470) as potassium bromide discs at Faculty
I
.
compound II (Fig. 1), under the name of laprafylline, of Pharmacy, Assiut University. NMR spectra were
is in Phase II clinical trials as a bronchodilator (Regnier recorded on either a Bruker DPX 300 MHz spectro-
et al., 1987; Baraldi et al., 2007). Furthermore, there meter at LIMES Institute, Program Unit Chemical
are some reports studied the antibacterial action of Biology & Medicinal Chemistry, or a Varian EM-360
xanthines and xanthine derivatives on various micro- 60 MHz spectrometer at Faculty of Pharmacy, Assiut
organisms, and proved that some compounds showed University. DMSO-d6 was used as a solvent, unless
significant activity (Raj and Dhala, 1965; Ashour et al
1993; Romanenko et al , 1997; Dianov and Bulgakov, in
2006). Chemical shifts are expressed either relative to tetra-
In a previous work (Elgaher et al , 2009), some 8- methylsilane (TMS) as an internal standard or to the
aralkylthiotheophylline derivatives were prepared, chemical shifts of the remaining protons of DMSO-d6
and showed either more or equipotent activity to that 1H: 2.49 ppm, 13C: 39.7 ppm. Protons of NH, and OH
.,
otherwise specified, and the chemical shifts are given
.
δ
(ppm), coupling constants ( ) are in Hertz (Hz).
J
.
:
δ
of aminophylline, and ampicillin as reference stand- groups were confirmed by D2O. The EI-MS were deter-
ards, also a pharmacophore model was constructed mined using either EI-Finnigan MAT 95XL (Thermo
based on reported compounds of known bronchodila- Finnigan) at LIMES Institute, Program Unit Chem-
tor activity to identify pharmacophoric structural fea- ical Biology & Medicinal Chemistry, or JOEL JMS600
tures of the active ligands. Accordingly, the present mass spectrometer at the Unit of Microanalysis, Assiut
work aims at the design and synthesis of some 8-subs- University, and ESI-HRMS were determined using
tituted theophylline derivatives as novel bronchodi- Concept 1H (Kratos), with
m-nitrobenzyl alcohol as a
lators with potent antibacterial activity. The designed matrix at LIMES Institute, Program Unit Chemical
compounds embody either annelated thiazole ring, or Biology & Medicinal Chemistry. The microanalyses
1,2,4-triazol-3-ylmethyl moiety at 8-position to enhance for C, H, N and S were performed on Perkin-Elmer
antibacterial activity, and explore their effect on bron- 240 elemental analyzer at the Unit of Microanalysis,
chodilator activity.
Assiut University.
1,3-Dimethyl-6-(4-(un)substituted phenyl)thia-
MATERIALS AND METHODS
Chemistry
zolo[2,3-f]purine-2,4(1H,3H)-diones (2a, 2b, 2d-g)
To a stirred freshly prepared polyphosphoric acid
Reagents used for synthesis were purchased from formed from phosphorus pentoxide (8 g) and phos-
Sigma-Aldrich and MERCK. All solvents were obtained phoric acid (6 mL), the appropriate 1,3-dimethyl-8-{[2-
from commercial suppliers and used without further (4-(un)substituted phenyl)-2-oxoethyl]thio}-3,7-dihydro-
purification. Melting points (mp) were determined on
1H-purine-2,6-dione 1a, 1b, 1d, 1e, 1f, or 1g (5.3 mmol)
an electrothermal Stuart Scientific SMP1 melting (Elgaher et al
.
, 2009) was added, and the reaction
point apparatus and were uncorrected. Thin-layer chro- mixture was heated at 140-150oC for 5-6 h. The reac-
matography (TLC, Rf values) was carried out using tion mixture was cooled, poured into ice-water and
TLC aluminium sheets kieselgel 60 F254 (MERCK) neutralized with saturated sodium carbonate solution.
and dichloromethane/methanol (9.5:0.5) as a mobile The precipitated solid was filtered, washed with water,
phase and visualization was effected with ultraviolet dried, and crystallized from the appropriate solvent
lamp Spectroline ENF-240C/F at short wavelength (Table I). Physical, microanalytical, and spectral data

New Theophylline Derivatives as Bronchodilator and Antibacterial Activities
5
are given in Table I and II.
H aliphatic); 1728, 1688, 1640 (C=O); 1534 (N-H); 1050
(C-O). H NMR (60 MHz): 3.46 (s, 3H, N1-CH3), 3.62
1
6-(4-Methoxyphenyl)-1,3-dimethylthiazolo[2,3-
f
]
(s, 3H, N3-CH3), 3.98 (s, 3H, OCH3), 4.47 (s, 2H, SCH2),
14.47 (br s, 1H, N7-H).
purine-2,4(1
A solution of 8-{[2-(4-methoxyphenyl)-2-oxoethyl]
thio}-1,3-dimethyl-3,7-dihydro-1 -purine-2,6-dione 1c 1,3-Dimethyl-2,6-dioxo-2,3,6,7-tetrahydro-1
(1.44 g, 4 mmol) (Elgaher et al , 2009) in glacial acetic rine-8-yl thioacetohydrazide (5)
acid (10 mL) was heated under reflux for about 48 h To a stirred solution of methyl [(1,3-dimethyl-2,6-
(TLC monitored), and then the reaction mixture was dioxo-2,3,6,7-tetrahydro-1 -purin-8-yl)thio]acetate
H,3H)-dione (2c)
H
H-pu-
.
H
4
poured into ice-water and neutralized with saturated (5.68 g, 0.02 mole) in absolute ethanol (80 mL), hydra-
sodium carbonate solution. The precipitated solid was zine hydrate 80% (2.5 mL) was added. The reaction
filtered, washed with water, dried, and crystallized mixture was refluxed for 2 h, and then cooled. The
from ethanol as pale yellow needles (Table I and II).
precipitate formed was filtered, washed with diethyl
ether, dried, and crystallized from ethanol as colorless
Methyl [(1,3-dimethyl-2,6-dioxo-2,3,6,7-tetrahydro- crystals.
-purin-8-yl)thio]acetate (4)
Yield: (5.2 g) 92%, mp: 280-281oC, as reported (Strokin
To a stirred solution of compound (5.3 g, 25 mmol) et al
, 1990). IR cm-1: 3415, 3240 (N-H); 2865 (C-H alipha-
(Elgaher et al
, 2009) in aqueous sodium hydroxide 1% tic); 1697, 1634 (C=O); 1533 (N-H). 1H NMR (60 MHz):
1H
3
.
.
w/v (100 mL), a solution of methyl bromoacetate (3.82 3.43 (s, 3H, N1-CH3), 3.60 (s, 3H, N3-CH3), 4.18 (s, 2H,
g, 25 mmol) dissolved in ethanol (10 mL) was added SCH2), 7.60 (br s, 3H, NHNH2), 14.02 (br s, 1H, N7-H).
portion wise. The reaction mixture was stirred at the
ambient temperature for 6 h, and then cooled in a 8-{[(4-Amino-5-thioxo-4,5-dihydro-1
H-1,2,4-triazol-
refrigerator for 3 h. The product was filtered, washed 3-yl)methyl]thio}-1,3-dimethyl-3,7-dihydro-1
H-pu-
with water, diethyl ether, dried, and crystallized from rine-2,6-dione (6)
methanol as colorless crystals.
To a stirred ice-cooled solution of 1,3-dimethyl-2,6-
Yield: 6.2 g (87%), mp: 215-216oC as reported dioxo-2,3,6,7-tetrahydro-1
H-purin-8-yl thioacetohydra-
(Karsovskii et al
.
, 1982). IR cm-1: 3430 (N-H); 2880 (C- zide
5
(2.84 g, 10 mmol), and potassium hydroxide
Table I. Physical and microanalytical data of compounds 2a-g
mp (oC)
Crystal. solvent
Mol. formula
(Mol. wt)
Microanalyses
No.
R
Yield %
70
Calcd. %
-
Found %
-
287-289a
Methanol/chloroform (8:2)
C15H12N4O2S
(312.34)
2a
H
-
C
H
N
S
58.08
4.42
16.93
9.69
57.85
4.63
17.29
10.10
C16H14N4O2S
·¼H2O
(330.87)
257-259
Ethanol
2b
CH3
72
C
H
N
S
55.40
4.21
16.15
9.24
55.67
4.48
15.71
9.70
C16H14N4O3S
·¼H2O
(346.87)
231-233
Ethanol
2c
2d
2e
OCH3
F
60
72
76
C
H
N
54.54
3.36
16.96
54.46
3.55
17.33
292-294
Methanol
C15H11FN4O2S
(330.33)
C
H
N
S
50.64
3.40
15.75
9.01
50.57
3.53
16.03
8.79
C15H11ClN4O2S
287-289
Ethanol
Cl
·½H2O
(355.79)
298-300a
Methanol/chloroform (8:2)
C15H11BrN4O2S
(391.24)
2f
Br
76
68
-
-
-
-
-
-
> 300a
DMSO/water (9:1)
C15H11N5O4S
(357.34)
2g
NO2
aMelting points as reported (Yurchenko et al
., 1974)

6
A. M. Hayallah et al.
Table II. Spectral dataa of compounds 2a
-g
No.
IR cm-1
3050 (Ar-H); 2930 (C-H aliphatic); 1689, 1647 3.50 (s, 3H, N3-CH3), 3.86 (s, 3H, N1-CH3), 7.15 (s, 1H, C7-H), 7.95
(C=O); 737, 691 (Ar-H) (s, 5H, Ar-H)
3060 (Ar-H); 2920 (C-H aliphatic); 1686, 1645 2.63 (s, 3H, 4'-CH3), 3.59 (s, 3H, N3-CH3), 3.95 (s, 3H, N1-CH3), 7.16
1H NMR (60 MHz)
2a
2b
2c
(C=O); 814 (Ar-H)
(s, 1H, C7-H), 7.70-8.17 (m, 4H, Ar-H)
3.63 (s, 3H, N3-CH3), 3.96 (s, 3H, N1-CH3), 4.24 (s, 3H, 4'-OCH3),
3060 (Ar-H); 2915 (C-H aliphatic); 1690, 1647
(C=O); 1212, 1032 (C-O); 808 (Ar-H)
7.20 (s, 1H, C7-H), 7.54 (d,
Hz, 2H, 2',6'Ar-H)
J = 8.8 Hz, 2H, 3',5'Ar-H), 8.07 (d, J = 8.8
3070 (Ar-H); 2935 (C-H aliphatic); 1693, 1650 3.22 (s, 3H, N3-CH3), 3.58 (s, 3H, N1-CH3), 6.56 (s, 1H, C7-H), 6.82-
(C=O); 1221 (C-F); 816 (Ar-H) 7.56 (m, 4H, Ar-H)
2d
2e
2f
3060 (Ar-H); 2920 (C-H aliphatic); 1689, 1647 3.52 (s, 3H, N3-CH3), 3.88 (s, 3H, N1-CH3), 7.23 (s, 1H, C7-H), 7.76-
(C=O); 1100 (C-Cl); 836 (Ar-H) 8.28 (m, 4H, Ar-H)
3055 (Ar-H); 2920 (C-H aliphatic); 1686, 1645 3.57 (s, 3H, N3-CH3), 3.92 (s, 3H, N1-CH3), 7.26 (s, 1H, C7-H), 7.95
(C=O); 815 (Ar-H) (d, = 8.8 Hz, 2H, 3',5'Ar-H), 8.24 (d, = 8.8 Hz, 2H, 2',6'Ar-H)
J
J
3065 (Ar-H); 2925 (C-H aliphatic); 1687, 1642 3.20 (s, 3H, N3-CH3), 3.51 (s, 3H, N1-CH3), 7.47 (s, 1H, C7-H), 7.81
(C=O); 1503, 1331 (NO2); 823 (Ar-H) (d, = 8.7 Hz, 2H, 3',5'Ar-H), 8.26 (d, = 8.7 Hz, 2H, 2',6'Ar-H)
2g
J
J
a 1H NMR spectra of compounds 2a-f were performed in CDCl3.
(0.84 g, 15 mmol) in absolute ethanol (100 mL), carbon 31.00; S, 17.79.
disulfide (1.14 g, 15 mmol) was added. The reaction
mixture was stirred at the ambient temperature for 8-({[4-Amino-5-alkylthio-4H-1,2,4-triazol-3-yl]meth-
16 h. Dry ether (60 mL) was then added, and the yl}thio)-1,3-dimethyl-3,7-dihydro-1
H-purine-2,6-
precipitated solid was filtered, washed with ether, and diones (7a-k)
dried. Potassium dithiocarbazate salt was obtained in
a quantitative yield, and was used in the next reaction in ethanol (40 mL) containing potassium hydroxide
without further purification. (0.33 g, 5.88 mmol), the appropriate alkyl halide or
To a stirred solution of compound 6 (2.0 g, 5.88 mmol)
N
-
A suspension of the dithiocarbazate salt (10 mmol) substituted aryl/aralkyl-2-chloroacetamide or 2-chloro-
in hydrazine hydrate 99% (20 mmol), and water (2 1-(4-phenylpiperazin-1-yl)ethanone (5.88 mmol) dis-
mL) was refluxed with stirring for 1 h. The color of the solved in ethanol (10 mL) was added. The reaction
reaction mixture changes to green, hydrogen sulfide mixture was refluxed for 4 h, cooled and then diluted
was evolved, and a homogenous solution was resulted. with 50 mL of water. The product was filtered, washed
The reaction mixture was cooled, diluted with ice-cold with water, diethyl ether, and dried. Crystallization
water, and acidified cautiously with concentrated hy- was performed from the appropriate solvent (Table
drochloric acid. The obtained precipitate was filtered, III). Physical, microanalytical, and spectral data are
washed with cold water, dried, and crystallized from listed in Table III and IV.
water as colorless rosette crystals.
Yield: 2.4 g (70%), Rf : 0.85, mp: 251-252oC. IR cm-1: Alkyl/aralkyl/aryl-
N
-[3-{[(1,3-dimethyl-2,6-dioxo-
-purin-8-yl)thio]methyl}-5-
-1,2,4-triazol-4-yl]carbox-
3445, 3260 (N-H); 2870 (C-H aliphatic); 1707, 1640 2,3,6,7-tetrahydro-1
H
(C=O); 1536 (N-H); 1465, 1450 (C=C, C=N); 1207 (C= (un)substituted thio-4
H
S). 1H NMR (300 MHz): 3.20 (s, 3H, N1-CH3), 3.39 (s, amides (8a-l)
3H, N3-CH3), 4.47 (s, 2H, triazole-CH2), 5.56 (s, 2H,
To a stirred suspension of compound
6 or its S-alkyl
NH2), 13.61 (br s, 2H, N7-H, N1'-H). 13C NMR (75 MHz): derivatives 7d
,
7e 7g, or 7i (2 mmol), and triethyl-
,
25.84 (triazole-CH2), 28.15 (N1-CH3), 30.24 (N3-CH3), amine (0.28 mL, 2 mmol) in tetrahydrofuran (20 mL),
108.81 (C5), 146.67 (C4), 148.57 (C8), 149.34 (C3'), the appropriate acid chloride (2 mmol) was added. The
151.34 (C2), 153.89 (C6), 166.83 (C5'). EI-MS (m/z, % reaction mixture was stirred at the ambient tempera-
base): 340.14 (M+, 1.6), 303.15 (100), 266.13 (0.6), ture for 12 h. The product was filtered, washed with
252.02 (23.3), 225.42 (0.8), 212.21 (22.7), 127.17 (4.6), diethyl ether, and dried. Crystallization was perform-
99.13 (12.5), 74.13 (8.6), 67.94 (17.8), 53.04 (3.0). ESI- ed from the appropriate solvent (Table V). Physical,
HRMS (m/z): 341.0610 (M++1) (calcd. 341.0597).
microanalytical, and spectral data are presented in
Anal. Calcd. for C10H12N8O2S2.H2O: C, 33.51; H, Table V and VI.
3.94; N, 31.26; S, 17.89. Found: C, 33.77; H, 4.28; N,

New Theophylline Derivatives as Bronchodilator and Antibacterial Activities
7
Table III. Physical and microanalytical dataa of compounds 7a
-k
mp (oC)
Crystal. solvent
Mol. formula
(Mol. wt)
Microanalyses
No.
R
Yield %
72
Calcd. %
Found %
C
H
N
40.82
4.74
29.30
40.64
4.87
29.42
206-208
Ethanol
C13H18N8O2S2
(382.46)
7a
C
H
N
S
48.63
4.53
25.21
14.43
48.35
4.78
24.88
13.99
242-244
Ethanol
C18H20N8O2S2
(444.53)
7b
7c
7d
75
74
72
C13H16N8O4S2
C
H
N
36.27
4.21
26.03
36.27
4.38
25.84
172-174
aq. ethanol 30%
·
H2O
(430.46)
C
H
N
46.81
4.34
25.86
46.56
4.67
25.44
247-249
aq. methanol 20%
C19H21N9O3S2
(487.55)
C
H
N
S
45.32
4.20
25.03
12.74
45.17
4.53
24.71
12.44
237-239
aq. methanol 20%
C19H21N9O4S2
(503.55)
7e
7f
80
76
C
H
N
42.56
3.57
24.82
42.25
3.24
24.48
241-244 dec.
aq. methanol 20%
C18H18ClN9O3S2
(507.97)
C
H
N
S
42.56
3.57
24.82
12.62
42.32
3.95
24.65
12.36
234-236
aq. methanol 20%
C18H18ClN9O3S2
(507.97)
7g
7h
7i
75
56
72
70
C18H18N10O5S2
C
H
N
40.29
3.76
26.11
40.30
3.61
25.85
268-271 dec.
DMF
·
H2O
(536.54)
C
H
N
47.89
4.62
25.13
47.61
4.73
24.96
253-255
DMF/water (9:1)
C20H23N9O3S2
(501.58)
C
H
N
47.89
4.62
25.13
47.65
4.88
24.90
205-207
DMF/water (9:1)
C20H23N9O3S2
(501.58)
7j
C
H
N
48.69
4.83
25.81
48.55
4.95
25.69
194-196
DMF/water (9:1)
C22H26N10O3S2
(542.63)
7k
70
aCompound 7a is further confirmed by ESI-HRMS which showed m/z 383.1068 (M++1) (calcd. 383.1067).
8-({[4-{[4-(Un)substituted benzylidene]amino}-5- of concentrated sulfuric acid were added. The reaction
(un)substituted thio-4 -1,2,4-triazol-3-yl]methyl} mixture was refluxed for 6 h, cooled and then diluted
H
thio)-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-diones with 20 mL of water. The product was filtered, wash-
(9a-j)
ed with water, and dried. Crystallization was perform-
To a stirred suspension of compound
6
or its
S-alkyl ed from the appropriate solvent (Table VII). Physical,
derivatives 7d, 7e, 7g, or 7i (2 mmol) in dioxane (20 microanalytical, and spectral data are given in Table
mL), the appropriate aldehyde (2 mmol) and two drops VII and VIII.

8
A. M. Hayallah et al.
Table IV. Spectral dataa of compounds 7a
-k
No.
IR cm-1
1H NMR (60 MHz)
= 7 Hz, 3H, CH2CH3), 1.65 (m, 2H, CH2CH2CH3), 3.06 (t, J =
7 Hz, 2H, SCH2CH2), 3.21 (s, 3H, N1-CH3), 3.40 (s, 3H, N3-CH3), 4.55 (s,
2H, triazole-CH2), 5.96 (s, 2H, NH2), 13.69 (br s, 1H, N7-H)
0.94 (t,
J
3290, 3185 (N-H); 2860 (C-H aliphatic);
1687, 1650 (C=O); 1537 (N-H)
7a
3170 (N-H); 3040 (Ar-H); 2870 (C-H 3.35 (m, 4H, SCH2CH2Ph), 3.47 (s, 3H, N1-CH3), 3.64 (s, 3H, N3-CH3),
aliphatic); 1694, 1652 (C=O); 1536 (N-H); 5.02 (s, 2H, triazole-CH2), 5.60 (br s, 2H, NH2), 7.83 (s, 5H, Ar-H), 13.96
7b
7c
7d
738, 696 (Ar-H)
(br s, 1H, N7-H)
3300, 3165 (N-H); 2925 (C-H aliphatic); 3.21 (s, 3H, N1-CH3), 3.41 (s, 3H, N3-CH3), 3.64 (s, 3H, OCH3), 3.97 (s,
1730, 1681, 1650 (C=O); 1536 (N-H); 2H, SCH2CO), 4.51 (s, 2H, triazole-CH2), 5.96 (s, 2H, NH2), 13.25 (br s,
1044 (C-O)
1H, N7-H)
3245 (N-H); 3040 (Ar-H); 2920 (C-H 2.26 (s, 3H, 2'-CH3), 3.23 (s, 3H, N1-CH3), 3.45 (s, 3H, N3-CH3), 3.95 (s,
aliphatic); 1695, 1635 (C=O); 1531 (N-H); 2H, SCH2CO), 4.62 (s, 2H, triazole-CH2), 6.75 (br s, 2H, NH2), 7.05-7.72
740 (Ar-H)
(m, 4H, Ar-H), 9.80 (br s, 1H, amide-H), 13.35 (br s, 1H, N7-H)
3.20 (s, 3H, N1-CH3), 3.39 (s, 3H, N3-CH3), 3.68 (s, 3H, 4'-OCH3), 4.00
(s, 2H, SCH2CO), 4.51 (s, 2H, triazole-CH2), 5.99 (br s, 2H, NH2), 6.75 (d,
3280 (N-H); 3100 (Ar-H); 2930 (C-H
aliphatic); 1692, 1634 (C=O); 1536 (N-H);
1248 (C-O); 815 (Ar-H)
7e
J
= 8.7 Hz, 2H, 3',5'Ar-H), 7.36 (d,
1H, amide-H), 13.47 (br s, 1H, N7-H)
J = 8.7 Hz, 2H, 2',6'Ar-H), 9.97 (br s,
3240 (N-H); 3040 (Ar-H); 2865 (C-H 3.07 (s, 3H, N1-CH3), 3.28 (s, 3H, N3-CH3), 3.73 (s, 2H, SCH2CO), 4.37
aliphatic); 1695, 1645 (C=O); 1528 (N-H); (s, 2H, triazole-CH2), 5.05 (br s, 2H, NH2), 6.66-7.72 (m, 4H, Ar-H), 9.52
7f
744 (Ar-H)
(br s, 1H, amide-H), 13.14 (br s, 1H, N7-H)
3270 (N-H); 3095 (Ar-H); 2945 (C-H 3.26 (s, 3H, N1-CH3), 3.42 (s, 3H, N3-CH3), 4.20 (s, 2H, SCH2CO), 4.62
aliphatic); 1690, 1636 (C=O); 1532 (N-H); (s, 2H, triazole-CH2), 6.08 (br s, 2H, NH2), 6.92-7.83 (m, 4H, Ar-H),
7g
772, 738 (Ar-H)
10.70 (br s, 1H, amide-H), 13.61 (br s, 1H, N7-H)
3.09 (s, 3H, N1-CH3), 3.36 (s, 3H, N3-CH3), 3.96 (s, 2H, SCH2CO), 4.35
3335, 3220 (N-H); 3095 (Ar-H); 2980 (C-
H aliphatic); 1684, 1640 (C=O); 1550 (N-
H); 1490, 1322 (NO2); 845 (Ar-H)
(s, 2H, triazole-CH2), 4.95 (br s, 2H, NH2), 7.55 (d,
2',6'Ar-H), 7.94 (d, = 8.7 Hz, 2H, 3',5'Ar-H), 10.39 (br s, 1H, amide-H),
13.66 (br s, 1H, N7-H)
J = 8.7 Hz, 2H,
7h
7i
J
1.32 (d, = 7 Hz, 3H, CHCH3), 3.15 (s, 3H, N1-CH3), 3.38 (s, 3H, N3-
CH3), 3.84 (s, 2H, SCH2CO), 4.37 (s, 2H, triazole-CH2), 4.83 (m, 1H,
J
3240 (N-H); 3040 (Ar-H); 2865 (C-H
aliphatic); 1697, 1637 (C=O); 1534 (N-H);
740, 693 (Ar-H)
NHCHCH3), 5.46 (br s, 2H, NH2), 7.08 (s, 5H, Ar-H), 8.49 (d,
1H, amide-H), 14.48 (br s, 1H, N7-H)
J = 7 Hz,
2.60 (t,
J
= 7 Hz, 2H, CH2CH2Ph), 3.11 (s, 3H, N1-CH3), 3.31 (s, 3H, N3-
3310, 3180 (N-H); 3055 (Ar-H); 2945 (C-
H aliphatic); 1694, 1641 (C=O); 1533 (N-
H); 740, 691 (Ar-H)
CH3), 3.48 (m, 2H, NHCH2CH2), 3.82 (s, 2H, SCH2CO), 4.47 (s, 2H,
triazole-CH2), 4.84 (br s, 2H, NH2), 7.05 (s, 5H, Ar-H), 8.12 (t,
1H, amide-H), 13.42 (br s, 1H, N7-H)
7j
J = 6 Hz,
3.01 (m, 4H, (CH2CH2)2NPh), 3.09 (s, 3H, N1-CH3), 3.26 (s, 3H, N3-
CH3), 3.47 (m, 4H, (CH2CH2)2NCO), 3.76 (s, 2H, SCH2CO), 4.39 (s, 2H,
triazole-CH2), 5.14 (br s, 2H, NH2), 6.46-7.26 (m, 5H, Ar-H), 14.22 (br s,
1H, N7-H)
3245, 3140 (N-H); 3040 (Ar-H); 2955 (C-
H aliphatic); 1693, 1635 (C=O); 1533 (N-
H); 746, 689 (Ar-H)
7k
a1H NMR spectra of compound 7a was measured by 300 MHz spectrometer.
hook was sutured to an isometric force transducer (Uni-
Bronchodilator activity
The method of Kesler and Canning (Kesler and versal oscillograph, Harvard).
Canning, 1999) was utilized with minor modifications
When the animals were stabilized, a bronchospasm
(Grosa et al , 1989). Male Hartley guinea pigs, 300-400 was stimulated with acetylcholine (0.2 mg/kg i.p.). After
.
g (House of Laboratory Animals, Faculty of Medicine, two similar responses to spasm inducing injections,
Assiut University) were anaesthetized with urethane target compounds (dissolved in distilled water with a
(1 g/kg i.p.) and positioned ventral side up on a wooden minimal amount of 1 N NaOH) (Baziard-Mouysset et
pad. The trachea was connected to a pump for arti- al., 1995) or aminophylline as a reference standard
ficial respiration, stainless steel hooks were passed were administered (2.5-10 mg/kg i.p.), acetylcholine
between two cartilage rings on either side of the trachea, was administered again three to five minutes later.
one hook was sutured to a fixed bar and the other The effects of the test compounds were expressed as

New Theophylline Derivatives as Bronchodilator and Antibacterial Activities
9
Table V. Physical and microanalytical data of compounds 8a-l
mp (oC)
Crystal. solvent
Mol. formula
(Mol. wt)
Microanalyses
Calcd. % Found %
No.
R
R1
Yield %
C
H
N
S
37.69
3.69
29.30
16.77
37.52
3.57
28.99
16.51
256-258
Dioxane/ether (7:3)
C12H14N8O3S2
(382.42)
8a
-
CH3
70
C
H
N
S
47.15
3.96
24.44
13.99
46.96
3.64
23.98
14.21
198-201 dec.
Dioxane/ether (7:3)
C18H18N8O3S2
(458.51)
8b
-
73
C17H15ClN8O3S2
C
H
N
41.85
3.31
22.96
279-282 dec.
Dioxane/ether (7:3)
41.59 3.30
22.71
8c
8d
-
-
76
76
·½H2O
(487.94)
C17H14Cl2N8O3S2
C
H
N
38.42
3.03
21.09
38.06
2.98
20.74
241-244 dec.
Dioxane/ether (7:3)
·
H2O
(531.39)
C
H
N
47.63
4.38
23.80
47.57
4.52
23.63
221-224 dec.
Methanol
C21H23N9O4S2
(529.59)
8e
8f
CH3
71
72
67
72
C
H
N
49.88
3.86
20.13
49.78
3.46
19.86
242-245 dec.
Methanol
C26H24ClN9O4S2
(626.11)
C
H
N
S
46.23
4.25
23.11
11.75
46.14
4.34
23.03
11.61
210-212
Ethanol
C21H23N9O5S2
(545.59)
8g
8h
CH3
C
H
N
S
48.63
3.77
19.63
9.99
48.44
3.85
19.35
9.77
216-218
Ethanol
C26H24ClN9O5S2
(642.11)
C
H
N
43.67
3.67
22.92
43.48
3.79
22.79
153-155
Ethanol
C20H20ClN9O4S2
(550.01)
8i
8j
CH3
CH3
70
72
C
H
N
46.44
3.27
19.50
46.44
3.06
19.38
196-198
Ethanol
C25H21Cl2N9O4S2
(646.52)
C
H
N
48.61
4.64
23.19
48.78
4.29
22.86
217-220 dec.
aq. ethanol 50%
C22H25N9O4S2
(543.62)
8k
8l
70
73
C
H
N
50.66
4.09
19.69
50.36
4.10
19.40
225-228 dec.
aq. ethanol 50%
C27H26ClN9O4S2
(640.13)
mean of percentage inhibition of five experiments ± al., 1994). At the end of each experiment, animals were
S.E.M. of the induced bronchospasm for three doses killed by cervical dislocation. Results are shown in
(2.5, 5, and 10 mg/kg body weight), ID50 value in each Table IX.
case was calculated by linear regression (Raeburn et

10
A. M. Hayallah et al.
Table VI. Spectral data of compounds 8a-l
No.
IR cm-1
1H NMR (60 MHz)
2.12 (s, 3H, CH3CO), 3.41 (s, 3H, N1-CH3), 3.66 (s, 3H, N3-CH3),
4.72 (s, 2H, triazole-CH2), 11.82 (br s, 1H, amide-H), 14.66 (br s,
2H, N7-H, N1'-H)
3275, 3120 (N-H); 2925 (C-H aliphatic); 1694,
1627 (C=O); 1534 (N-H); 1226 (C=S)
8a
3386 (N-H); 3090 (Ar-H); 2920 (C-H aliphatic); 3.19 (s, 3H, N1-CH3), 3.33 (s, 3H, N3-CH3), 3.64 (s, 2H, CH2Ph),
1693, 1633 (C=O); 1535 (N-H); 1210 (C=S); 4.39 (s, 2H, triazole-CH2), 7.17 (s, 5H, Ar-H), 8.10 (br s, 1H, amide-
8b
8c
8d
735, 685 (Ar-H)
3140 (N-H); 3040 (Ar-H); 2965 (C-H aliphatic); 3.10 (s, 3H, N1-CH3), 3.32 (s, 3H, N3-CH3), 4.50 (s, 2H, triazole-
1692, 1632 (C=O); 1533 (N-H); 1211 (C=S); CH2), 7.31 (d, = 8.8 Hz, 2H, 3',5'Ar-H), 7.68 (d, = 8.8 Hz, 2H,
839 (Ar-H) 2',6'Ar-H), 11.58 (br s, 1H, amide-H), 13.61 (br s, 2H, N7-H, N1'-H)
H), 13.25 (br s, 2H, N7-H, N1'-H)
J
J
3140 (N-H); 3030 (Ar-H); 2890 (C-H aliphatic); 3.19 (s, 3H, N1-CH3), 3.42 (s, 3H, N3-CH3), 4.18 (s, 2H, triazole-
1692, 1644 (C=O); 1537 (N-H); 1222 (C=S); CH2), 7.10-7.80 (m, 3H, Ar-H), 9.75 (br s, 1H, amide-H), 10.40 (br
837 (Ar-H)
s, 2H, N7-H, N1'-H)
1.78 (s, 3H, CH3CO), 2.10 (s, 3H, 2'-CH3), 3.09 (s, 3H, N1-CH3),
3195 (N-H); 3085 (Ar-H); 2935 (C-H aliphatic); 3.29 (s, 3H, N3-CH3), 3.90 (s, 2H, SCH2CO), 4.48 (s, 2H, triazole-
8e
8f
1695, 1642 (C=O); 1534 (N-H); 740 (Ar-H)
CH2), 6.82-7.57 (m, 4H, Ar-H), 9.72 (br s, 1H, amide-H), 10.02 (br
s, 1H, amide-H), 13.23 (br s, 1H, N7-H)
2.45 (s, 3H, 2'-CH3), 3.12 (s, 3H, N1-CH3), 3.36 (s, 3H, N3-CH3),
4.04 (s, 2H, SCH2CO), 4.49 (s, 2H, triazole-CH2), 6.87-7.94 (m, 8H,
Ar-H), 10.05 (br s, 1H, amide-H), 10.27 (br s, 1H, amide-H), 13.10
(br s, 1H, N7-H)
3365, 3155 (N-H); 3040 (Ar-H); 2870 (C-H
aliphatic); 1692, 1645 (C=O); 1543 (N-H); 837,
740 (Ar-H)
2.08 (s, 3H, CH3CO), 3.12 (s, 3H, N1-CH3), 3.31 (s, 3H, N3-CH3),
3.62 (s, 3H, 4'-OCH3), 3.95 (s, 2H, SCH2CO), 4.48 (s, 2H, triazole-
3300, 3120 (N-H); 3045 (Ar-H); 2970 (C-H
aliphatic); 1691, 1637 (C=O); 1537 (N-H);
1248 (C-O); 821 (Ar-H)
8g
8h
8i
CH2), 6.69 (d,
J = 8.7 Hz, 2H, 3',5'Ar-H), 7.30 (d, J = 8.7 Hz, 2H,
2',6'Ar-H), 10.12 (br s, 2H, amide-H), 13.12 (br s, 1H, N7-H)
3290, 3100 (N-H); 3045 (Ar-H); 2920 (C-H 3.15 (s, 3H, N1-CH3), 3.35 (s, 3H, N3-CH3), 3.65 (s, 3H, 4'-OCH3),
aliphatic); 1690, 1635 (C=O); 1537 (N-H); 4.00 (s, 2H, SCH2CO), 4.52 (s, 2H, triazole-CH2), 6.66-7.62 (m, 8H,
1249 (C-O); 815 (Ar-H)
Ar-H), 10.22 (br s, 2H, amide-H), 13.18 (br s, 1H, N7-H)
2.05 (s, 3H, CH3CO), 3.09 (s, 3H, N1-CH3), 3.27 (s, 3H, N3-CH3),
3.94 (s, 2H, SCH2CO), 4.44 (s, 2H, triazole-CH2), 6.80-7.72 (m, 4H,
Ar-H), 10.04 (br s, 1H, amide-H), 10.65 (br s, 1H, amide-H), 14.45
(br s, 1H, N7-H)
3280, 3145 (N-H); 3040 (Ar-H); 2915 (C-H
aliphatic); 1691, 1640 (C=O); 1533 (N-H); 749,
707 (Ar-H)
3270, 3175 (N-H); 3095 (Ar-H); 2915 (C-H 3.14 (s, 3H, N1-CH3), 3.34 (s, 3H, N3-CH3), 3.99 (s, 2H, SCH2CO),
aliphatic); 1689, 1633 (C=O); 1531 (N-H); 814, 4.47 (s, 2H, triazole-CH2), 6.82-7.70 (m, 8H, Ar-H), 10.20 (br s, 2H,
8j
768, 739 (Ar-H)
amide-H), 12.65 (br s, 1H, N7-H)
1.32 (d, = 7 Hz, 3H, CHCH3), 1.96 (s, 3H, CH3CO), 3.18 (s, 3H,
J
3330, 3200 (N-H); 3090 (Ar-H); 2940 (C-H N1-CH3), 3.33 (s, 3H, N3-CH3), 3.98 (s, 2H, SCH2CO), 4.47 (s, 2H,
aliphatic); 1691, 1642 (C=O); 1534 (N-H); 739, triazole-CH2), 4.80 (m, 1H, NHCHCH3), 7.13 (s, 5H, Ar-H), 8.52 (d,
8k
8l
692 (Ar-H)
J = 7 Hz, 1H, amide-H), 10.02 (br s, 1H, amide-H), 13.65 (br s, 1H,
N7-H)
1.32 (d,
J = 7 Hz, 3H, CHCH3), 3.16 (s, 3H, N1-CH3), 3.37 (s, 3H,
3155 (N-H); 3040 (Ar-H); 2960 (C-H aliphatic);
1693, 1648 (C=O); 1540 (N-H); 836, 739, 683
(Ar-H)
N3-CH3), 4.06 (s, 2H, SCH2CO), 4.50 (s, 2H, triazole-CH2), 4.92 (m,
1H, NHCHCH3), 6.92-8.00 (m, 9H, Ar-H), 8.58 (d, = 7 Hz, 1H,
amide-H), 10.20 (br s, 1H, amide-H), 13.29 (br s, 1H, N7-H)
J
Control Unit, Assiut Univeristy Hospital, Faculty of
Medicine, Assiut University).
Antibacterial activity
Organisms and culture conditions
Four bacterial species representing both Gram-
positive and Gram-negative strains were used to test
the antibacterial activity of the target compounds:
Agar cup diffusion method
The sterile Petri dishes were seeded with 100 µL of
methicillin resistant Staphylococcus aureus (MRSA), the microorganism; a specified amount of the molten
Bacillus cereus
Escherichia coli, and Klebsiella pneu- Mueller-Hinton (MH) agar medium (45-50oC) was
moniae (clinical isolates were obtained from Infection poured into the seeded Petri dishes to give a depth of
,

New Theophylline Derivatives as Bronchodilator and Antibacterial Activities
11
Table VII. Physical and microanalytical data of compounds 9a-j
mp (oC)
Crystal. Solvent
Mol. formula
(Mol. wt)
Microanalyses
Calcd. % Found %
No.
R
-
R1
Yield %
68
C
H
N
47.65
3.76
47.46
3.80
26.07
218-220
Ethanol
C17H16N8O2S2
(428.49)
9a
H
26.15
C
H
N
47.15
3.96
24.44
47.11
4.07
24.39
229-231
Ethanol
C18H18N8O3S2
(458.51)
9b
9c
-
OCH3
H
70
70
C
H
N
54.25
4.38
21.90
54.17
4.22
21.64
201-203
Dioxane/ether (7:3)
C26H25N9O3S2
(575.66)
C
H
N
53.54
4.49
20.81
53.23
4.35
20.60
221-223
Dioxane/ether (7:3)
C27H27N9O4S2
(605.69)
9d
9e
9f
OCH3
H
70
71
71
68
68
65
66
C
H
N
S
52.78
4.26
21.31
10.84
52.69
4.48
21.67
10.47
203-205
Dioxane
C26H25N9O4S2
(591.66)
C
H
N
S
52.16
4.38
20.28
10.32
52.53
4.43
20.53
10.74
230-232
Dioxane/ether (7:3)
C27H27N9O5S2
(621.69)
OCH3
H
C
H
N
S
50.37
3.72
21.15
10.76
50.75
3.58
21.29
10.60
207-209
DMF/water (9:1)
C25H22ClN9O3S2
(596.08)
9g
9h
9i
C
H
N
S
49.88
3.86
20.13
10.24
49.66
3.95
20.26
10.70
228-230
DMF/water (9:1)
C26H24ClN9O4S2
(626.11)
OCH3
H
C
H
N
S
54.99
4.62
21.38
10.88
54.69
4.83
21.30
11.04
212-214
Dioxane/ether (7:3)
C27H27N9O3S2
(589.69)
C
H
N
S
54.27
4.72
20.34
10.35
54.17
4.92
20.55
10.46
222-224
Dioxane/ether (7:3)
C28H29N9O4S2
(619.71)
9j
OCH3
3-4 mm and allowed to solidify. Cylindrical plugs were method (Scott, 1989) for compounds having moderate
removed from the agar using sterile cork borer. One to strong antibacterial activity. The squares of inhi-
hundred µL of the test compounds or ampicillin sodium bition zone diameters were plotted against log concen-
(20 mg/mL in DMSO), or the solvent, were added to trations of the test compounds. Extrapolation of the
the wells in triplicate. The seeded plates were incu- resulting straight line to intersect with log concentra-
bated at 37oC for 24 h then the average diameters of tion scale in the curve corresponds to log MIC, and
the inhibition zones were measured in millimeters. MIC was obtained as antilog (Hewitt, 1977). Results
Results are shown in Table X.
are shown in Table X.
Minimum inhibitory concentration
Acute toxicity (LD50)
The MIC was determined using the two-fold dilution
Groups of male adult albino mice, 18-22 g (House of

12
A. M. Hayallah et al.
Table VIII. Spectral data of compounds 9a-j
No.
IR cm-1
1H NMR (60 MHz)
3325 (N-H); 3100 (Ar-H); 2990 (C-H aliphatic); 3.12 (s, 3H, N1-CH3), 3.28 (s, 3H, N3-CH3), 4.52 (s, 2H, triazole-
1687, 1636 (C=O); 1537 (N-H); 1457, 1451 CH2), 7.07-8.00 (m, 5H, Ar-H), 8.62 (s, 1H, N=CH), 13.90 (br s,
9a
(C=C, C=N); 1211 (C=S); 748, 690 (Ar-H)
3435 (N-H); 3095 (Ar-H); 2920 (C-H aliphatic); 3.10 (s, 3H, N1-CH3), 3.26 (s, 3H, N3-CH3), 3.78 (s, 3H, 4-OCH3),
1712, 1626 (C=O); 1590, 1497, 1444 (C=C, 4.48 (s, 2H, triazole-CH2), 6.97 (d, = 8.7 Hz, 2H, 3',5'Ar-H), 7.78
C=N); 1539 (N-H); 1248 (C-O); 1209 (C=S); 825 (d, = 8.8 Hz, 2H, 2',6'Ar-H), 8.56 (s, 1H, N=CH), 13.68 (br s, 2H,
2H, N7-H, N1'-H)
J
9b
9c
9d
9e
J
(Ar-H)
N7-H, N1'-H)
2.21 (s, 3H, 2'-CH3), 3.06 (s, 3H, N1-CH3), 3.24 (s, 3H, N3-CH3),
3.68 (s, 2H, SCH2CO), 4.43 (s, 2H, triazole-CH2), 6.75-7.88 (m,
9H, Ar-H), 8.44 (s, 1H, N=CH), 9.64 (br s, 1H, amide-H), 13.61 (br
s, 1H, N7-H)
3380 (N-H); 3105 (Ar-H); 2990 (C-H aliphatic);
1687, 1636 (C=O); 1535 (N-H); 1500, 1441
(C=C, C=N); 781, 745, 690 (Ar-H)
2.18 (s, 3H, 2'-CH3), 3.07 (s, 3H, N1-CH3), 3.22 (s, 3H, N3-CH3),
3.77 (s, 3H, 4-OCH3), 3.98 (s, 2H, SCH2CO), 4.43 (s, 2H, triazole-
CH2), 6.60-7.84 (m, 9H, Ar-H), 8.38 (s, 1H, N=CH), 9.37 (s, 1H,
amide-H), 13.56 (br s, 1H, N7-H)
3440 (N-H); 3100 (Ar-H); 2915 (C-H aliphatic);
1710, 1627 (C=O); 1591, 1497, 1446 (C=C,
C=N); 1541 (N-H); 1250 (C-O); 824, 747 (Ar-H)
3.08 (s, 3H, N1-CH3), 3.25 (s, 3H, N3-CH3), 3.68 (s, 3H, 4'-OCH3),
4.06 (s, 2H, SCH2CO), 4.51 (s, 2H, triazole-CH2), 6.48-7.94 (m,
9H, Ar-H), 9.76 (s, 1H, N=CH), 10.00 (s, 1H, amide-H), 13.64 (br
s, 1H, N7-H)
3280 (N-H); 3100 (Ar-H); 2920 (C-H aliphatic);
1690, 1637 (C=O); 1536 (N-H); 1501, 1438
(C=C, C=N); 1236 (C-O); 823, 749, 690 (Ar-H)
3.08 (s, 3H, N1-CH3), 3.23 (s, 3H, N3-CH3), 3.65 (s, 3H, 4'-OCH3),
3.73 (s, 3H, 4-OCH3), 3.99 (s, 2H, SCH2CO), 4.45 (s, 2H, triazole-
CH2), 6.48-7.82 (m, 8H, Ar-H), 9.44 (s, 1H, N=CH), 9.95 (br s, 1H,
amide-H), 13.68 (br s, 1H, N7-H)
3435 (N-H); 3095 (Ar-H); 2915 (C-H aliphatic);
1691, 1631 (C=O); 1591, 1501, 1441 (C=C,
C=N); 1537 (N-H); 1249 (C-O); 824 (Ar-H)
9f
9g
9h
3445 (N-H); 3105 (Ar-H); 2920 (C-H aliphatic); 3.08 (s, 3H, N1-CH3), 3.23 (s, 3H, N3-CH3), 4.02 (s, 2H, SCH2CO),
1689, 1636 (C=O); 1597, 1439 (C=C, C=N); 4.43 (s, 2H, triazole-CH2), 6.66-7.88 (m, 9H, Ar-H), 9.68 (s, 1H,
1537 (N-H); 748, 710, 687 (Ar-H)
N=CH), 10.30 (br s, 1H, amide-H), 13.73 (br s, 1H, N7-H)
3305 (N-H); 3110 (Ar-H); 2945 (C-H aliphatic); 3.05 (s, 3H, N1-CH3), 3.22 (s, 3H, N3-CH3), 3.78 (s, 3H, 4-OCH3),
1692, 1629 (C=O); 1589, 1503, 1444 (C=C, 3.89 (s, 2H, SCH2CO), 4.40 (s, 2H, triazole-CH2), 6.55-7.77 (m,
C=N); 1537 (N-H); 1251 (C-O); 825, 766, 731 8H, Ar-H), 9.32 (s, 1H, N=CH), 10.43 (br s, 1H, amide-H), 13.63
(Ar-H)
(br s, 1H, N7-H)
1.32 (d, = 7 Hz, 3H, CHCH3), 3.08 (s, 3H, N1-CH3), 3.23 (s, 3H,
N3-CH3), 3.88 (s, 2H, SCH2CO), 4.47 (s, 2H, triazole-CH2), 4.62
(m, 1H, NHCHCH3), 6.65-7.88 (m, 10H, Ar-H), 8.48 (d, = 7 Hz,
1H, amide-H), 9.73 (s, 1H, N=CH), 13.64 (br s, 1H, N7-H)
1.30 (d, = 7 Hz, 3H, CHCH3), 3.06 (s, 3H, N1-CH3), 3.21 (s, 3H,
J
3355 (N-H); 3085 (Ar-H); 2890 (C-H aliphatic);
1690, 1636 (C=O); 1535 (N-H); 1486, 1440
(C=C, C=N); 748, 689 (Ar-H)
9i
9j
J
J
3450 (N-H); 3090 (Ar-H); 2900 (C-H aliphatic);
1711, 1625 (C=O); 1590, 1501, 1442 (C=C,
C=N); 1537 (N-H); 1248 (C-O); 825, 748, 691
(Ar-H)
N3-CH3), 3.72 (s, 3H, 4-OCH3), 3.94 (s, 2H, SCH2CO), 4.39 (s, 2H,
triazole-CH2), 4.61 (m, 1H, NHCHCH3),
6.62-7.87 (m, 9H, Ar-H), 8.38 (d,
J = 7 Hz, 1H, amide-H), 9.38 (s,
1H, N=CH), 13.36 (br s, 1H, N7-H)
Laboratory Animals, Faculty of Medicine, Assiut Uni-
versity), each of five animals, were injected intraperi-
toneal (i.p.) with 4 graded doses of the test compounds
suspended in 0.5% carboxymethylcellulose. LD50 was
RESULTS AND DISCUSSION
Chemistry
Thiazolo[2,3-f]xanthine derivatives were prepared
calculated on the number of animals showing decre- from the corresponding 8-aroylmethylthioxanthine
ased muscle tone, and laboured respiration signs derivatives by using different dehydrating agents like
according to Litchfield and Wilcoxon’s method (Litchfield phosphorus oxychloride (POCl3) (Ochiai, 1936), ethanolic
and Wilcoxon, 1949; Grosa et al
.
, 1989; Akhila et al
.,
HCl (Uno et al., 1972), sulfuric acid 96% (Yurchenko
2007). Results are shown in Table XI.
et al , 1974), glacial acetic acid (Yurchenko et al.,
.
1974), and polyphosphoric acid (PPA) (Hayallah, 2007;
Hayallah and Famulok, 2007). The reaction is usually
catalyzed by enhancing electrophilicity of the carbonyl

New Theophylline Derivatives as Bronchodilator and Antibacterial Activities
13
Table IX. Inhibitory effects of the test compounds on acet-
ylcholine induced bronchospasm in anaesthetized guinea-
pigs
Table X. Antibacterial activity of the test compounds
In vitro activity-inhibition zone in mm
(MIC in µg/mL)
% Decrease of
acetylcholine induced
Com-
pound
Methicillin
Dose
ID50
Compound
resistant
Staphylococcus cereus
aureus (MRSA)
a
Bacillus Escherichia Klebsiella
mg/kg i.p.
bronchospasm in mg/kg i.p.
guinea pigs
coli
pneumoniae
12.5
15
10
22.5 ± 1.1
48.6 ± 1.4
78.8 ± 1.1
DMSO
Ampicillin
2a
2b
2c
2d
2e
2f
-
-
-
-
Aminophylline
5.8
9.1
7.2
9.8
8.0
8.8
7.7
8.6
7.7
11.9
7.9
8.4
5.8
6.5
7.0
6.9
020 0(69)
-
17 (125)
-
33 0(20)
-
22 0(60) 23 0(50)
20 0(70)
-
-
-
-
-
12.5
15
10
15.1 ± 0.9
34.3 ± 0.9
52.6 ± 0.9
18 0(79)
11 (177)
-
-
2b
2c
2d
2e
6
22 0(60) 16 (130)
20 0(76) 17 (125)
20 0(76) 17 (125)
20 0(76) 17 (125)
21 0(73) 17 (120)
18 (130)
21 0(73)
21 0(73)
21 0(73)
18 (127)
-
12.5
15
10
18.5 ± 1.2
38.5 ± 1.6
66.8 ± 1.4
-
-
2g
4
5
12.5
15
10
14.1 ± 1.2
34.3 ± 1.7
48.9 ± 1.9
32 0(22)
-
-
-
6
17 (125)
-
16 (153) 15 (158)
21 0(73) 13 (168)
15 (158)
20 0(76)
-
12.5
15
10
18.0 ± 1.2
36.4 ± 1.6
59.8 ± 1.8
7a
7b
7c
7d
7e
7f
7g
7h
7i
-
-
-
-
-
22 0(70) 17 (125)
19 0(86)
19 0(86)
27 0(45)
23 0(61)
12 (170)
20 0(76)
21 0(71)
-
22 0(70)
26 0(40)
-
36 0(30)
-
23 0(65)
27 0(50)
39 0(38)
35 0(34)
20 0(76)
12 (170)
32 0(25)
33 0(27)
31 0(38)
33 0(24)
12 (173)
13 (168)
33 0(31)
33 0(25)
-
12.5
15
10
19.7 ± 1.1
33.5 ± 1.4
55.2 ± 1.2
-
-
28 0(31)
15 (157)
9 (178)
14 (161)
18 0(80)
-
17 (125)
17 (125)
-
29 0(33) 18 (127)
16 (154)
15 (157) 12 (170)
16 (154)
18 0(80) 20 0(76)
-
12.5
15
10
16.2 ± 1.2
36.4 ± 1.6
62.7 ± 2.2
7d
7e
7f
-
12.5
15
10
15.8 ± 1.2
34.3 ± 1.4
56.0 ± 1.4
7j
-
-
-
-
-
7k
8a
8b
8c
8d
8e
8f
8g
8h
8i
17 (125)
11 (177)
-
12.5
15
10
17.1 ± 1.2
36.4 ± 1.6
62.1 ± 1.5
33 0(22)
-
35 0(27) 34 0(28)
12.5
15
10
12.5 ± 1.0
30.7 ± 1.5
41.3 ± 1.8
-
-
7i
29 0(35)
27 0(24)
32 0(26)
31 0(29)
16 (154)
13 (168)
32 0(27)
31 0(30)
32 0(22)
32 0(20)
17 (125)
12 (173)
31 0(20)
32 0(20)
13 (168)
14 (161)
-
29 0(26) 24 0(53)
28 0(28) 26 0(41)
30 0(20) 33 0(34)
38 0(27) 33 0(29)
12.5
15
10
18.4 ± 1.1
36.4 ± 1.5
60.3 ± 1.5
7j
-
-
16 (153)
23 0(63)
12.5
15
10
16.9 ± 1.3
36.4 ± 1.6
56.8 ± 1.9
8j
8k
8l
8b
8c
8h
9a
9b
32 0(23) 31 0(25)
30 0(30) 33 0(27)
30 0(26) 33 0(24)
31 0(22) 33 0(24)
12.5
15
10
25.6 ± 1.3
46.4 ± 1.6
78.5 ± 1.9
9a
9b
9c
9d
9e
9f
9g
9h
9i
-
-
16 (154)
-
12.5
15
10
21.6 ± 1.5
42.1 ± 1.6
71.8 ± 1.9
30 0(25) 33 0(25)
30 0(26) 32 0(22)
12.5
15
10
19.4 ± 1.3
38.5 ± 1.6
68.0 ± 1.8
-
-
-
-
12 (173)
-
-
-
12.5
15
10
20.8 ± 1.6
40.0 ± 1.8
68.5 ± 1.6
9j
31 0(32)
27 0(30)
23 0(50) 25 0(45)
a(-) means no antibacterial activity at the studied concen-
tration.

14
A. M. Hayallah et al.
Table XI. Acute toxicity in mice following i.p. injection of
compounds 2c, 7d, 8c, and 9b
Utilization of PPA in cyclodehydration of 1c to give
the title compound 2c was unfavorable due to partial
demethylation of the
ture of -methoxy, and
in accordance to reported findings (El-Shorbagi et al
2001). The required compound 2c could be prepared
by refluxing 1c in glacial acetic acid for 48 h, to avoid
demethylation process.
p
-methoxy group to afford a mix-
Compound
LD50 mg/kg
p
p-hydroxy cyclized derivatives
2c
7d
8c
9b
300
300
300
.,
300
Aminophylline
aLD50 value as reported (Peikov et al
., 1994)
a180a
Compound
solution of compound
an equimolar amount of methyl bromoacetate. Reac-
, 1974). In the pre- tion of with hydrazine hydrate 80% in ethanol under
2b, and 2d-g were prepar- reflux for 2 h afforded compound , Fig. 4. Compounds
ed by cyclodehydration of compounds 1a 1b, and 1d- and were previously published with no H NMR
in PPA at 140-150oC for 5-6 h, Fig. 2. Privilege of data (Karsovskii et al
, 1982) and (Strokin et al , 1990),
this method is that the products are more pure, and respectively. In the present work, we have character-
the yields are considerably high (68-76%).
ized them by determining their mp, IR, as well as 1H
IR spectra of these new cyclized derivatives are char- NMR spectra.
acterized by disappearance of both N7-H stretching Compound
4
was prepared by reacting the aqueous
3
in sodium hydroxide 1% with
carbon by acids (Yurchenko et al
sent work, compounds 2a
.
4
,
5
1
,
4
5
g
.
.
6
was prepared by reaction of the acid
band at 3445 cm-1, and its bending band at 1536 cm-1, hydrazide
5 with carbon disulfide in ethanolic potas-
which were taken as evidences for cyclization. 1H NMR sium hydroxide, and subsequent hydrazinolysis of the
spectrum of the new products showed disappearance formed potassium dithiocarbazate salt, Fig. 4. IR spec-
of both protons of -SCH2- and N7-H groups, and ap- trum of
pearance of a singlet at
6.56-7.47 ppm corresponding 3445, and 3260 cm-1, two strong absorption bands at
to C7-H, and this is a good evidence of cyclization. In 1707, and 1640 cm-1 corresponding to C=O stretching,
addition, two singlets at 3.20-3.63 and
3.51-3.96 and appearance of C=S stretching band at 1207 cm-1,
ppm corresponding to N3-CH3 and N1-CH3, respecti- and absence of an absorption at about 2600-2550 cm-1
vely, and the signals corresponding to aromatic moieties region cited for SH group (Silverstein et al , 2005),
were appeared. EI-mass spectra of these compounds which was taken as a proof that compound exists
showed molecular ion peaks in agreement with their mainly in the thione form in the soild state. 1H NMR
molecular masses, and behaved in similar fragmenta- spectrum of compound showed two singlet signals at
tion patterns. The molecular ion peak of all the com- 3.20 and 3.39 ppm each equivalent to three pro-
pounds was the base peak, and the main fragment peaks tons characteristic to N1 and N3 methyl groups respec-
were corresponding to M-57, M-58, M-85, and M-113. tively, a singlet at 4.47 ppm corresponding to -SCH2-
The proposed fragmentation pattern of compound 2e group, a singlet at
5.56 ppm corresponding to NH2
group, and a broad singlet at 13.61 ppm correspond-
6 showed two broad N-H stretching bands at
δ
δ
δ
.
6
6
δ
δ
δ
δ
is shown in Fig. 3.
δ
Fig. 2. Synthetic pathway for the preparation of compounds 2a-g

New Theophylline Derivatives as Bronchodilator and Antibacterial Activities
15
Fig. 3. Proposed mass fragmentation pattern of compound 2e
ing to N7-H, and N1'-H protons. 13C NMR spectrum sorption bands at 1730-1634 cm-1 corresponding to
revealed a signal at 166.83 ppm corresponding to the C=O stretching bands. Absence of C=S stretching
δ
thioketone group at C5' which was another evidence band is an evidence for introduction of the targeted
for existence of the thione form. Structure of compound moieties, Table IV. 1H NMR spectra of compounds 7a-
6
was further confirmed by using DEPT technique.
Signal at 25.84 ppm corresponding to -SCH2- invert- 3.64 ppm each equivalent to three protons character-
ed, and signals at 28.15 and 30.24 ppm correspond- istic to N1 and N3 methyl groups, respectively, a
ing to N1 and N3 methyl groups respectively remain- singlet at 4.35-5.02 ppm corresponding to C8-SCH2-
ed upward, and all other signals of quaternary carbons group, a singlet at 4.84-6.75 ppm corresponding to
disappeared. ESI-HRMS spectrum showed M++1 peak NH2 group, and a broad singlet at
13.14-14.48 ppm
at m/z 341.0610 which was in accordance with the corresponding to N7-H proton. In addition, the signals
calculated value (341.0597). corresponding to the newly introduced moieties were
k showed two singlet signals at δ 3.07-3.47 and δ 3.26-
δ
δ
δ
δ
δ
Alkylation of the thioxo group of the triazole ring to appeared (Table IV). These compounds were also con-
give compounds 7a-k, was performed according to a firmed by elemental analyses, and some of them by
reported procedure (Karthikeyan et al
ing a solution of compound
in ethanolic potassium pound 7a showed M++1 peak at m/z 383.1068 which
hydroxide with an equimolar amount of the appropri- was in accordance with the calculated value (383.1067).
ate alkyl halide or -substituted aryl/aralkyl-2-chloro- Acylation of N4'-amino group of the triazole ring was
acetamide or 2-chloro-1-(4-phenylpiperazin-1-yl)etha- performed according to a reported procedure (Pajkert
none, and refluxing the reaction mixture for 4 h, Fig. et al , 2009) by treating a suspension of compound
4. IR spectra of the new alkylated derivatives 7a-k or its -alkyl derivatives 7d 7e 7g 7i in tetrahydro-
., 2008) by treat- ESI-HRMS (Table III). ESI-HRMS spectrum of com-
6
N
.
6,
S
,
,
,
were characterized by presence of sharp absorption furan, in presence of triethylamine, with an equimolar
bands at 3335, 3140 cm-1 corresponding to asymmetric amount of the appropriate acid chloride, and stirring
and symmetric stretching frequencies of primary NH2 the reaction mixture at the ambient temperature for
group, in addition to the original N7-H stretching band 12 h, Fig. 4 and 5. IR spectra of the new products were
of xanthine around 3455 cm-1, presence of strong ab- characterized by presence of N-H stretching band at

16
A. M. Hayallah et al.
3386-3100 cm-1, an absorption band at 3100 cm-1 cor- 1438 cm-1 corresponding to C=C, and C=N stretching
responding to Ar-H stretching frequency except for vibrations. 1H NMR spectra of these new derivatives
compound 8a, and also presence of strong absorption are characterized by appearance of two singlet signals
bands at 1712-1625 cm-1 corresponding to C=O stre- at
tching bands, in addition to absorption bands at 1597- three protons characteristic to N1 and N3 methyl
δ
3.09-3.41 and
δ 3.27-3.66 ppm each equivalent to
Fig. 4. Synthetic pathway for the preparation of compounds 6, 7a-k, 8a-d, and 9a,b

New Theophylline Derivatives as Bronchodilator and Antibacterial Activities
17
groups respectively, a singlet at
responding to C8-SCH2- group. Disappearance of amino confirmed by elemental analyses (Table V).
group signal around 6.00 ppm and appearance of a Schiff bases, compounds 9a-j, were prepared accord-
broad singlet around 10.20 ppm corresponding to ing to a reported procedure (Holla and Akberali, 1991)
δ 4.18-4.72 ppm cor- group (Table VI). These amide derivatives were further
δ
δ
amide-H proton are evidences for acylation of NH2 through a reaction of
6 or its S-alkyl derivatives 7d,
Fig. 5. Synthetic pathway for the preparation of compounds 8e-l, and 9c-j

18
A. M. Hayallah et al.
7e
,
7g
,
7i in dioxane, with an equimolar amount of
Regarding the results of 8-[(4-amino-5-alkylthio-
the appropriate (un)substituted benzaldehyde, in pre- 1,2,4-triazol-3-yl)methyl]thioxanthine series (7d-f, 7i,
sence of a catalytic amount of concentrated sulfuric and 7j) (ID50 7.7-11.9 mg/kg), it can be observed that
acid, Fig. 4 and 5. IR spectra of the new Schiff bases all the compounds exhibited moderate activities.
are characterized by presence of absorption bands at
3386-3100 cm-1 corresponding to N-H stretching fre- methyl}-5-(un)substituted thio-1,2,4-triazol-3-yl]car-
quency of amide groups, in addition to the original boxamide series (8b 8c, and 8h). It can be observed
N7-H stretching band of xanthine around 3455 cm-1. that
-acylation of 4-amino-1,2,4-triazole moiety in-
In the alkyl/aralkyl/aryl-N-[3-{[(theophylline-8-yl)thio]
,
N
Also, presence of strong absorption bands at 1695- creases the bronchodilator activity.
N-(p-chloroben-
1627 cm-1 corresponding to C=O, along with a medium zamido) derivative (8c) showed an equipotent activity
absorption bands at 1537 cm-1 corresponding to N-H to aminophylline (ID50 5.8 mg/kg).
bending vibrations were detected. 1H NMR spectra of
In the 8-({[4-{[4-(un)substituted benzylidene]amino}-
these Schiff bases revealed presence of two singlet 5-(un)substituted thio-1,2,4-triazol-3-yl]methyl}thio)
signals at 3.05-3.12 and 3.22-3.28 ppm each equiva- theophylline series (9a and 9b) (ID50 7.0 and 6.9 mg/
lent to three protons characteristic to N1 and N3 kg), respectively. Formation of Schiff bases at 4-amino-
methyl groups, respectively, a singlet at 4.39-4.52 1,2,4-triazole moiety augments the bronchodilator acti-
ppm corresponding to C8-SCH2- group, a hump at vity.
13.36-13.90 ppm corresponding to N7-H proton, and Results of compounds
δ
δ
δ
δ
6, 7d-f, 7i, 7j, 8b, 8c, 8h, 9a,
other signals corresponding to the new introduced and 9b indicate that substitution at 4-amino-1,2,4-
moieties (Table VIII). Disappearance of amino group triazole moiety either by acylation or Schiff bases
signal around
δ
6.00 ppm and appearance of a singlet formation, generally led to higher activity than the
. While alkylation at 5-mer-
at 8.38-9.76 ppm corresponding to N=CH proton are free amino compound
δ
6
evidences for introduction of the targeted moieties.
capto-1,2,4-triazole moiety did not improve potency,
on the contrary, it may diminish activity markedly in
some cases e.g. compound 7i (ID50 11.9 mg/kg).
Bronchodilator activity
Fifteen of the target compounds were selected – in
view of the pharmacophore search results (Elgaher et
Antibacterial activity
al., 2009) and investigated for in vivo bronchodilator
Antibacterial activity of all the target compounds
activity by acetylcholine induced bronchospasm in was investigated in vitro against the Gram-positive
anaesthetized guinea-pigs using aminophylline as a bacteria methicillin resistant Staphylococcus aureus
reference standard. The bronchodilator effect was ex- (MRSA) and Bacillus cereus, and the Gram-negative
pressed as mean of percentage inhibition of five ex- bacteria Escherichia coli and Klebsiella pneumoniae
periments ± S.E.M. of the induced bronchospasm for using the agar diffusion assay. MIC of the active
three doses (2.5, 5, and 10 mg/kg body weight), ID50 compounds was calculated using the two-fold dilution
value in each case was calculated by linear regression. method. Ampicillin was used as a reference standard.
Results are shown in Table IX.
Five compounds (2c 8c 8h 9a, and 9b) exhibited a
bronchodilator activity nearly similar to that of amino- compound 2d induced higher activity than ampicillin
phylline (ID50 5.8 mg/kg). Compound 8c was equipo- against Gram-positive bacteria (MIC 20-60 g/mL),
and moderate activity against Gram-negative ones
Results are shown in Table X.
,
,
,
In the 6-arylthiazolo[2,3- ]xanthine series (2a-g),
f
µ
tent to aminophylline.
In view of these results, regarding the 6-(4-(un)sub- (MIC 130 µg/mL). Compounds 2e-g showed equipot-
stituted phenyl)thiazolo[2,3-
), all the test compounds showed moderate activities,
although slightly lower than their corresponding non activities against E. coli (MIC 125
cyclized precursors (1b-e) (Elgaher et al , 2009). There- activity against MRSA. It can be concluded that pre-
fore, cyclization of some compounds of series to sence of fluorine atom as -substituent highly potenti-
f
]theophylline series (2b- ent activities to ampicillin against B. cereus (MIC 76
g/mL), and K. pneumoniae (MIC 73 g/mL), moderate
g/mL), and no
e
µ
µ
µ
.
1
2
p
series, slightly, reduces the activity of some compounds ates the antibacterial activity. Only compounds which
2b and 2c. This may be attributed to annelation of the have electron withdrawing groups (halogen or nitro)
purine ring with the thiazole one.
were active against B. cereus, and Gram-negative bac-
To study the effect of introduction of 4-amino-5- terial strains. Cyclization of 8-aroylmethylthioxan-
mercapto-1,2,4-triazol-3-ylmethyl moiety at 8-position thines (1a-g) to their corresponding 6-arylthiazolo[2,3-
of theophylline on bronchodilator activity, compound
showed a moderate activity (ID50 8.8 mg/kg).
6
f
]xanthines (2a-g), generally, reduces the antibacterial
activity against MRSA except for compound 2d
.

New Theophylline Derivatives as Bronchodilator and Antibacterial Activities
19
Methyl theophyllin-8-ylthioacetate
activity than ampicillin against MRSA (MIC 22
mL), an equipotent activity against B. cereus (MIC 73 consideration, we can suggest that the mechanism of
g/mL), and moderate activity against Gram-negative action of our target xanthine derivatives as antibac-
bacteria (MIC 120-127 g/mL). On the other hand, the terial agents is through inhibition of nucleic acid syn-
corresponding hydrazide has no activity at the thesis.
studied concentration against any of the test bacterial
strains. Compound showed moderate activity against
all the test bacterial strains (MIC 125-158 g/mL).
4
afforded higher T bases and PO2 group of DNA through hydrogen
µ
g/ bonding (Nafisi et al , 2008). Taking these data into
.
µ
µ
5
6
Acute toxicity (LD50)
µ
Acute toxicity (LD50) study was performed in mice
In the 8-[(4-amino-5-alkylthio-1,2,4-triazol-3-yl)methyl] via intraperitoneal (i.p.) injection for four selected
thio-xanthine series (7a-k), compound 7e showed compounds 2c 7d 8c, and 9b in comparison to that of
higher activity than ampicillin against Gram-positive aminophylline as a reference standard. Results are
bacteria (MIC 31-33 g/mL), and against K. pneumo- shown in table XI. Data showed that all the test
niae (MIC 45 g/mL), but it showed moderate activity compounds did not record any significant toxicity up to
against E. coli (MIC 127 g/mL). Other compounds LD50 = 300 mg/kg in comparison with aminophylline
showed moderate activities against Gram-negative LD50 = 180 mg/kg (Peikov et al , 1994). The maximal
bacteria (MIC 61-170 g/mL), and weak or no activities toxicity was observed after 12 h, when the animals
against Gram-positive bacteria (MIC 70-178 g/mL). showed decreased muscle tone and labored respiration
In the alkyl/aralkyl/aryl- -[3-{[(theophylline-8-yl) signs.
thio]methyl}-5-(un)substituted thio-1,2,4-triazol-4-yl]
carboxamide series (8a-l), compounds 8c 8e-h 8k
and 8l showed higher activities than ampicillin against
all the test bacterial strains (MIC 20-65 g/mL). It can
be observed that
,
,
µ
µ
µ
.
µ
µ
N
,
,
,
ACKNOWLEDGEMENTS
µ
The authors are greatly indebted to Prof. Dr. Mi-
-alkylation at the triazole moiety of chael Famulok, director of LIMES Institute, Program
S
this series improved the antibacterial activity.
Unit Chemical Biology & Medicinal Chemistry, Bonn,
In the 8-({[4-{[4-(un)substituted benzylidene]amino}- Germany, for doing the 1H NMR, 13C NMR, ESI-HRMS
5-(un)substituted thio-1,2,4-triazol-3-yl]methyl}thio) for some compounds in his laboratory. Great thanks
theophylline series (9a-j), compounds 9a
,
9b
,
9e
,
9f,
are presented to Prof. Dr. Ahmed Osman, Department
and 9j showed higher activities than ampicillin against of Pharmacology, Faculty of Medicine, Assiut Univer-
all the test bacterial strains (MIC 20-50
Regarding the results of compounds
µ
g/mL).
sity, for his kind supervision of the bronchodilator
activity. And to M.Pharm.Sci. Helal F. Hetta, Depart-
6
,
7a-k, 8a-l,
and 9a-j we can conclude that introduction of 1,2,4- ment of Microbiology and Immunology, Faculty of
triazole moiety improved the activity against Gram- Medicine, Assiut University, Assiut, for his sincere
negative bacteria. Substitution at 4-amino-1,2,4-tria- help in screening of the antibacterial activity.
zole moiety either by acylation or Schiff bases forma-
tion, generally led to higher activity than unsubsti-
tuted triazole , and its -alkylated derivatives 7a-k
Generally, introduction of 1,2,4-triazole ring as a sub-
stituent to xanthine skeleton increased the antibac-
terial activity.
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