Synthesis and hypoglycemic activity of some new theophylline derivatives

Article abstract of DOI:10.3109/14756366.2013.795957

Thirty-one new theophylline derivatives have been synthesized and evaluated for their hypoglycemic activity. Compounds 24 (56% reduction) and 31 (57% reduction) showed better hypoglycemic activity than the standard drug glibenclamide which showed 52% redu

Full text of DOI:10.3109/14756366.2013.795957

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ISSN: 1475-6366 (print), 1475-6374 (electronic)
J Enzyme Inhib Med Chem, 2014; 29(3): 443–448
2014 Informa UK Ltd. DOI: 10.3109/14756366.2013.795957
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RESEARCH ARTICLE
Synthesis and hypoglycemic activity of some new theophylline
derivatives
Ahmed M. Alafeefy1, Saleh I. Alqasoumi2, Sami G. Abdel hamid1,3, Kamal E. H. El-Tahir4, Menshawy Mohamed1,3
Mohamed E. Zain5, and Amani S. Awaad6
,
1Department of Pharmaceutical Chemistry and 2Department of Pharmacognosy, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia,
3Department of Organic Chemistry, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt, 4Department of Pharmacology and Toxicology, College
5
6
of Pharmacy, Botany and Microbiology Department, Faculty of Science, and Chemistry Department, Faculty of Science, King Saud University,
Riyadh, Saudi Arabia
Abstract
Keywords
Thirty-one new theophylline derivatives have been synthesized and evaluated for their
hypoglycemic activity. Compounds 24 (56% reduction) and 31 (57% reduction) showed better
hypoglycemic activity than the standard drug glibenclamide which showed 52% reduction
in serum glucose level. Compound 27 remarkably reduced serum glucose level by 53%.
Ten compounds showed varying degrees of hypoglycemic activity ranging from 20 to 37%
reduction in serum glucose level compared to the standard drug. The aromatic amide
functionality is the common feature of these theophylline hypoglycemic derivatives. However,
anthranilamide and or aliphatic amides proved to be the least active compounds in the present
series.
Hypoglycemic, isoindoline, synthesis,
theophylline
History
Received 24 March 2013
Revised 11 April 2013
Accepted 11 April 2013
Published online 22 May 2013
Introduction
suggested that adenosine hepatic effects are mediated by the A2
receptors. It has also been reported that abnormal hepatic
glucose production rather than decreased muscle glucose uptake
is the major factor responsible for both fasting and postprandial
Non-insulin dependent diabetes mellitus (NIDDM) is a complex
disorder of heterogeneous etiology and characterized by abnormal
insulin secretion, decrease in the response of peripheral tissue
to insulin (insulin resistance) and increased hepatic glucose
production. These metabolic abnormalities cause hyperglycemia
in NIDDM patients, and this hyperglycemia is regarded as the
most important cause of diabetic complications.
Therefore, a major therapeutic goal in NIDDM patients is to
optimize blood glucose control to prevent the risk of complica-
tions resulting from vascular disease1.
It was reported that substitution at the eighth position of
theophylline, mainly with phenyl or cycloalkyl groups increases
the activity at adenosine receptors2. Significant effort has
been spent in defining more precisely a physiological role for
adenosine receptor related processes in the cardiovascular system
and in the central nervous system. The purine bases also have
effects on the pituitary–adrenocortical axis, increasing the release
hyperglycemia in NIDDM6–8
.
9-Methyladenine derivatives have been reported to act
as antagonists of adenosine, but not agonists. 2-Substituted
9-alkyladenine and 2-alkyl-8-aryl-9-methyladenine derivatives
have been reported as adenosine antagonists9,10
.
8-Phenyltheophylline inhibited a nonselective, N-ethylcarbox-
amidoadenosine (NECA) induced glucose production in primary
cultured rat hepatocytes, both in a dose-dependent manner11. This
Accumulation of facts promoted us to synthesize some new
theophylline derivatives modified at position 7 with acetohydra-
zide derivatives and investigate the possibility of developing new
antidiabetic agent.
Results and discussion
of a number of hormones, including dopamine, as part of a stress- Chemistry
related response3,4
.
The fact that substituted theophylline derivatives exerted inter-
esting biological activities12–16 promoted us to prepare the
7-acetohydrazide derivative 3 by hydrazinolysis of the ethyl
acetate ester derivative 2.
Adenosine is involved in glucose homeostasis5. It has been
reported that A1 adenosine receptor antagonism improves glucose
tolerance by increasing glucose uptake in skeletal muscle in
Zucker rats. Studies with specific agonists and antagonists
The synthetic strategy to prepare the target compounds 4–21 is
depicted in Figures 1 and 2. The theophylline acetohydrazide
derivative 3 was reacted with the appropriate reagents, e.g.
benzene-1,2-diamine, some aldehydes, ketones, acid chlorides
and anhydrides to afford the corresponding final derivatives
in considerable yields. The structures of the intermediates
Address for correspondence: Ahmed M. Alafeefy, Associate Prof. of
Pharmaceutical Chemistry, College of Pharmacy, Salman bin Abdulaziz
University, Al-Kharj, Saudi Arabia. Tel: +966 1 5454573. Cell phone:
+966 507069896. E-mail: a.alafeefy@sau.edu.sa
1
and final compounds were confirmed by elemental analysis, H,

444 A. M. Alafeefy et al.
J Enzyme Inhib Med Chem, 2014; 29(3): 443–448
O
N
CH
1
Figure 1. Reagents and conditions:
a ¼ BrCH2CO2Et/K2CO3/reflux. b ¼ ben-
zene-1,2-diamine/fusion. c ¼ N2H4ꢀH2O/
reflux. d ¼ aldehyde and/or /ketone
/C2H5OH/ reflux. e ¼ pyridine/reflux.
f ¼ benzoxazone/pyridine/reflux.
H
N
H C
N
3
N
a
b
T
OEt
T
N
H
N
O
O
3
2
4
c
O
H
N
R
H
N
N
Ar
N
e
NHNH
d
H C
2
N
T
3
N
N
T
N
O
3
O
O
5: R=CH3, Ar= C6H .
5
CH
6: R=CH3, Ar= C6H CH (p).
3
4
3
16
7: R=CH3, Ar= C6H Cl(p).
4
f
8: R=CH3, Ar= C6H4NO (p).
2
9: R=CH3, Ar= cyclohexyl.
O
CH
N
NHCOAr
2
O
10: R=CH , Ar= 2-thienyl.
H C
3
3
H
N
11: R=H, Ar= C6H .
N
5
T=
N
T
12: R=H, Ar= C6H4CH (p).
N
H
3
N
O
O
13: R=H, Ar= C H Cl(p).
6
4
CH
3
17: Ar= C6H .
5
14: R=H, Ar= C6H4NO (p).
2
18: Ar= C H Cl(p).
6
4
15: R=H, Ar= styryl.
19: Ar= C H4NO (p).
6
2
O
Figure 2. Reagents and conditions:
a ¼ phenylisothiocyanate/dioxane/TEA/
reflux. b ¼ acid anhydride/CH3CO2H/
CH3CO2Na/ reflux. c ¼ acid chloride/DMF/
see experimental. d ¼ aromatic acid anhy-
dride/CH3CO2H/ CH3CO2Na/ reflux.
e ¼ sulfonyl chloride derivative/pyridine/
reflux.
O
H
CH
N
2
C6H HN
N
5
H C
N
T
3
N
H
O
S
20
T=
N
H
N
N
CH
O
N
T
3
O
21
a
O
b
O
H
N
T
N
H
NHNH
R
2
T
d
c
O
N
N
X
T
O
H
O
O
22: X= H.
23: X= Cl.
3
25: R= acetyl.
26: R= phenacyl.
27: R= benzoyl.
28: R=2-thienoyl.
e
24: X= NO .
2
O
T
HN
NH
X
S
O
O
29: X=H, 30: X=CH , 31: X=NO .
3
2
13C NMR and Mass spectra (MS) and were found in accordance by exerting 56%, 53% and 57% reduction in serum glucose.
with the proposed structures (Table 1).
Glibenclamide showed 52% reduction in glucose blood level
(Table 2). The hypoglycemic effect could result from either
b-cells stimulation, and/or the insulin-like action on peripheral
tissues or through both mechanisms. However, work is going on
to find out the exact mechanism of action.
Hypoglycemic activity
All the target compounds (4–21) were screened for their
hypoglycemic activities. Fundamental signs of diabetes mellitus
such as hyperglycemia, loss of body weight, polyphagia and
polydipsia were induced in rats by injection of streptozotocin17–19
Structure-activity correlation
.
Subsequently, animals were treated with the compounds under Three compounds showed interesting hypoglycemic activities.
test and glibenclamide as a positive control. Ten compounds Compounds 24 and 27 incorporated the phthalimide and
12–14, 16, 17, 22, 23, 26, 29 and 30, in the present study, were benzamide moieties; however compound 31 contained 4-nitro-
able to ameliorate the signs of diabetes mellitus as compared to benzene sulfonamide joined to the theophylline backbone.
the diabetic untreated rats. Glibenclamide produced a significant These compounds proved to be the most active members in
blood glucose lowering effect compared to untreated rats which our study. Compounds 12–14, 16, 17, 22, 23, 26, 29 and 30
is mainly due to its insulin-like action20. These 10 compounds showed 20–37% reduction in serum glucose level. Structure–
showed 26, 25, 20, 35, 20, 24, 37, 30, 31 and 33% reduction activity correlation among this series showed that the type
in serum glucose level, respectively; however, compounds 24, 27 of phthalimide and/or benzamide functionality is crucial for
and 31 were the most effective hypoglycemic agent in this work activity as presented by compound 24 (theophylline-diimide 56%)

DOI: 10.3109/14756366.2013.795957
Synthesis and hypoglycemic activity of theophylline derivatives 445
Table 1. Melting points, crystallization solvents, yield percentages, Table 2. Effect of 14 days oral treatment of test compounds 4–31
molecular formulae and molecular weights of compounds (4–31). (10 mg/kg) or glibenclamide (10 mg/kg) on serum glucose (mean ꢃ SD).
Compound
number
M.P.
(ꢁC)
Cryst.
Solv.
Yield
(%)
Molecular formula
(Mol. Wt.)
Compound number
Serum/G (mg/dL)
Serum/G reduction (%)
4
5
6
7
8
466.8 ꢃ 55.8
0.0
0.0
0.0
0.0
0.0
6.0
0.0
13.0
26.0
25.0
20.0
18.0
35.0
20.0
0.0
4
5
6
7
8
215–7
230–2
295–7
286–8
291–3
224–26
212–4
221–3
235–7
242–44
224–6
237–9
278–80
4300
4300
4300
237–9
219–21
206–8
4300
4300
219–21
245–7
245–7
205–7
267–9
4300
4300
EtOH
EtOH
EtOH
AcOH
AcOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
AcOH
EtOH
AcOH
AcOH
AcOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
AcOH
AcOH
EtOH
AcOH
AcOH
EtOH
90
82
82
75
77
75
70
70
64
75
69
49
68
65
71
75
76
64
69
77
65
64
63
68
60
78
75
73
C15H14N6O2 (310.31)
462.9 ꢃ 52.00
463.8 ꢃ 56.79
464.2 ꢃ 55.28
462.6 ꢃ 49.97
435.9 ꢃ 54.39
461.2 ꢃ 25.06
402.9 ꢃ 77.18
341.7 ꢃ 20.16*
349.5 ꢃ 101.28
371.6 ꢃ 30.51
381.8 ꢃ 14.75
301.8 ꢃ 30.17*
370.5 ꢃ 32.70
467.3 ꢃ 20.43
465.4 ꢃ 102.82
418.4 ꢃ 19.72
469.9 ꢃ 23.08
352.6 ꢃ 31.25
290.8 ꢃ 29.29
204.3 ꢃ 21.15
452.8 ꢃ 15.41
365.9 ꢃ 44.9*
216.5 ꢃ 25.3**
379.8 ꢂ 25.52a
320.3 ꢃ 41.75*
310.3 ꢃ 35.15*
201.5 ꢃ 32.7**
91.77 ꢃ 8.98
C
C
C
C
C
C
C
C
C
C
C
17H18N6O3 (354.36)
18H20N6O3 (368.39)
17H17ClN6O3 (388.81)
17H17N7O5 (399.36)
17H24N6O3 (360.41)
15H16N6O3S (360.39)
16H16N6O3 (340.34)
17H18N6O3 (354.36)
9
9
10
11
12
13
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
16H15ClN6O3 (374.78) 14
16H15N7O5 (385.33)
18H18N6O3 (366.37)
15
16
17
18
19
20
21
22
23
C9H10N6O2 (234.21)
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
23H21N7O5 (475.46)
23H20ClN7O5 (509.9)
23H20N8O7 (520.45)
16H17N7O3S (387.42)
13H14N6O5 (334.29)
17H14N6O5 (382.33)
0.0
10.0
0.0
24.0
37.0
56.0
2.0
30.0
53.0
18.0
31.0
33.0
57.0
–
17H13ClN6O5 (416.78) 24
17H13N7O7 (427.33)
11H14N6O4 (294.27)
17H18N6O4 (370.36)
16H16N6O4 (356.34)
14H14N6O4S (362.36)
15H16N6O5S (392.39)
16H18N6O5S (406.42)
15H15N7O7S (437.39)
25
26
27
28
29
30
31
Vehicle control
Diabetic control
Glibenclamide
464.8 ꢃ 39.45b
224.7 ꢃ 21.7**
–
52.0
*p50.05 and **p50.01 versus diabetic control (Student’s t-test).
–, compounds showed increase in serum glucose concentration.
ap50.05 versus vehicle control.
and 27 (theophylline-benzamide 53%); however, compound 31
(sulfonamide containing theophylline, 57%) was almost as
effective as its amide and diimide congeners. Except for
compound 26, replacement of the amide, sulfamide or diimide
with anthranilamide or aliphatic ones has little to do with blood
glucose lowering effect according to the results obtained in the
current study. From these observations, it became clear that our
future efforts have to be devoted towards developing aromatic
amides and/or sulfonamides bearing theophylline derivatives in
order to elaborate more on the structure–activity relationship of
such interesting class of hypoglycemic compounds.
bp50.01 versus vehicle control.
Elemental analyses (C, H, N) were performed on Perkin-Elmer
2400 analyzer (Perkin-Elmer, Norwalk, CT) and were in full
agreement with the proposed structures within 0.4% of the
theoretical values. NMR spectra (DMSOd6) were obtained on a
Bruker AC 300 Ultra Shield NMR spectrometer (Bruker, Munich,
1
Germany) at 300 MHz for H and 75 MHz for 13C, the chemical
Conclusion
shifts are expressed in ꢀ (ppm) downfield from tetramethylsilane
(TMS). Splitting patterns were designated as follows: s: singlet;
d: doublet; t: triplet; m: multiplet. Electron impact mass spectra
were recorded on a Varian Mat 311-A70eV instrument (Varian,
Fort Collins, CO). Chemicals used are supplied from Sigma-
Aldrich (Sigma-Aldrich Chemie GmbH, Steinheim, Germany).
Adult Wistar albino male rats, weighing (200–250 g body
weight; 10–12 weeks old), were provided by Experimental
Animal Care Center, College of Pharmacy, King Saud
University, Riyadh, Kingdom of Saudi Arabia. The animals
were housed in cages under standard controlled environmental
conditions of humidity, temperature (25 ꢂ 2 ꢁC) and light (12 h
light/12 h dark). They were allowed free access to pulverized
standard rat pellet diet and tap water ad lib. All animal
experiments were according to the accepted standards of human
animal care in accordance with the NIH guidelines and the legal
requirements in Kingdom of Saudi Arabia. Streptozotocin (4%
w/v) was dissolved in fresh citrate-dextrose buffer (pH 4.5–5.0).
Glibenclamide was dissolved in distilled water and administered
In the present study, certain new amide, diimide and their related
sulfonamide isosters were synthesized and evaluated for their
hypoglycemic activity. Most of the synthesized compounds
showed promising hypoglycemic effect. Compound 2-(1,2,3,4,
5,6-hexahydro-1,3-dimethyl-2,6-dioxopurin-7-yl)-N-(5-nitro-1,3-
dioxoiso-indolin-2-yl)acetamide (24), N0-benzoyl-2-(1,2,3,4,5,6-
hexahydro-1,3-dimethyl-2,6-dioxopurin-7-yl)acetoohydrazide (27)
and
N0-4-nitrobenzenesulfonyl-2-(1,2,3,4,5,6-hexahydro-1,3-
dimethyl-2,6-dioxopurin-7-yl)acetoohydrazide (31) showed 56,
53, and 57% reduction in serum glucose level, respectively.
Glibenclamide showed only 52% reduction. The obtained results
showed that compounds 24, 27 and 31 could be useful as a
template for future development, modification and exploration to
produce more active analogs.
Experimental
Chemistry
All melting points (ꢁC, uncorrected) were determined on a Stuart immediately after preparation. The test compounds were
melting point apparatus (Stuart Scientific, Redhill, UK). formulated with 1.0–1.5% sodium carboxymethyl cellulose

446 A. M. Alafeefy et al.
J Enzyme Inhib Med Chem, 2014; 29(3): 443–448
1
10: H-NMR ꢀ: 1.05 (s, 3H, CH3), 2.79 (s, 6H, 2NCH3CO),
(CMC) in distilled water mixed on a magnetic stirrer at 50 ꢁC for
30 min prior to gavages administration. The glucose kit was 3.55 (S, 3H, N3-CH3), 5.50 (s, 2H, NCH2CO), 7.20–7.76 (m, 3H,
purchased from Randox Laboratories LTD (Crumlin, UK)21.
Ar-H), 8.12 (s, 1H, N ¼ CH), 9.18 (brs, 1H, CONH). 13C NMR: ꢀ
13.5 (CH3), 28.6(CH3), 30.1(CH3), 32.8(CH2N), 108.3, 125.3,
127.0, 128.5, 129.4, 145.8, 151.0, 151.8 (Ar-C), 153.9, 155.2,
163.5 (3C ¼ O). MS (EI): m/z 360 [Mþ]. Anal. (C15H16N6O3S)
Calcd/Found: C, 49.99 (50.24); H, 4.47 (4.69); N, 23.32 (23.59);
S, 8.90 (9.14).
Synthesis
7-[(1H-benzo[d]imidazol-2-yl)-methyl]-1,3-dimethyl-1H-purine
2,6(3H,7H)-dione 4
An equimolecular amount of compound 2 and benzene-1,2-
diamine (0.005 mol) was mixed thoroughly, ground and fused at
200 ꢁC for 30 min in a sand bath. The reaction mixture was
extracted with boiling acetic acid (30 ml), cooled and poured into
ice water (50 ml). The solid obtained was filtered, washed with
water, dried and crystallized from acetic acid to afford 4.
N0-Benzylidene-2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-
purin-7-yl) acetohydrazide 11–15
A mixture of 3 (0.005 mol) and the appropriate aldehyde
(0.0075 mol) in glacial acetic acid (20 ml) was heated under
reflux for 24 h. The reaction mixture was cooled and the solid
separated was filtered, dried and crystallized from acetic acid to
obtain 11–15.
11: 1H-NMR ꢀ: 2.73 (s, 6H, 2NCH3CO), 4.52 (s, 2H,
NCH2CO), 7.56–8.52 (m, 6H, Ar-H), 8.73 (s, 1H, N ¼ CH),
9.16 (brs, 1H, CONH). 13C NMR: ꢀ 29.2 (CH3), 30.2 (CH3), 32.5
(CH2N), 107.9, 128.3, 129.7, 131.6, 134.0, 143.5, 147.1, 150.6
(Ar-C), 152.8, 155.1, 163.5 (3C ¼ O). MS (EI): m/z 340 [Mþ].
Anal. (C16H16N6O3) Calcd/Found: C, 56.47 (56.67); H, 4.74
(4.51); N, 24.69 (24.85).
12: 1H-NMR ꢀ: 2.50 (s, 3H, Ar-CH3), 2.74 (s, 6H, 2NCH3CO),
4.55 (s, 2H, NCH2CO), 7.14–8.15 (m, 5H, Ar-H), 8.53 (s, 1H,
N ¼ CH), 9.12 (brs, 1H, CONH). 13C NMR: ꢀ 25.0 (CH3), 29.1
(CH3), 30.3 (CH3), 32.4 (CH2N), 107.7, 129.3, 129.7, 130.6,
140.9, 143.6, 146.3, 150.7 (Ar-C), 152.5, 154.3, 163.7 (3C ¼ O).
MS (EI): m/z 354 [Mþ]. Anal. (C17H18N6O3) Calcd/Found: C,
57.62 (57.33); H, 5.12 (5.65); N, 23.72 (23.90).
13: 1H-NMR ꢀ: 2.71 (s, 6H, 2NCH3CO), 4.54 (s, 2H,
NCH2CO), 7.32–8.11 (m, 5H, Ar-H), 8.45 (s, 1H, N ¼ CH),
9.11 (brs, 1H, CONH). 13C NMR: ꢀ 29.1 (CH3), 30.2 (CH3), 32.3
(CH2N), 108.0, 129.3, 129.7, 131.5, 137.2, 143.5, 146.2, 150.1
(Ar-C), 152.4, 154.6, 163.2 (3C ¼ O). MS (EI): m/z 374 [Mþ].
Anal. (C16H15ClN6O3) C, H, N.
14: 1H-NMR ꢀ: 2.76 (s, 6H, 2NCH3CO), 4.51 (s, 2H,
NCH2CO), 7.80–8.22 (m, 5H, Ar-H), 8.37 (s, 1H, N ¼ CH),
9.13 (brs, 1H, CONH). 13C NMR: ꢀ 29.4 (CH3), 30.7 (CH3), 32.3
(CH2N), 107.8, 125.8, 127.0, 132.5, 133.8, 143.7, 146.4, 150.0
(Ar-C), 152.3, 154.9, 163.5 (3C ¼ O). MS (EI): m/z 385 [Mþ].
Anal. (C16H15N7O5) Calcd/Found: C, 49.87 (50.01); H, 3.92
(3.78); N, 25.44 (25.17).
15: 1H-NMR ꢀ: 2.70 (s, 6H, 2NCH3CO), 4.53 (s, 2H,
NCH2CO), 5.50–5.78 (m, 2H, Olefinic-H), 7.52–8.01 (m, 6H,
Ar-H), 8.15 (s, 1H, N ¼ CH), 8.75 (brs, 1H, NHCO). 13C NMR: ꢀ
29.2 (CH3), 30.2 (CH3), 32.5 (CH2), 108.1, 126.4, 128.4, 128.9,
135.2, 137.7, 139.4, 146.8, 150.8 (Ar-C), 151.9, 155.4, 164.6
(3C ¼ O). MS (EI): m/z 366 [Mþ]. Anal. (C18H18N6O3) Calcd/
Found: C, 59.01 (58.86); H, 4.95 (5.16); N, 22.94 (23.12).
1
4: H-NMR ꢀ: 2.79 (s, 6H, 2NCH3CO), 4.88 (s, 2H, NCH2),
7.26–7.73 (m, 4H, Ar-H), 8.01 (s, 1H, N ¼ CH), 9.37 (brs, 1H,
CONH).). 13C NMR: ꢀ 29.0 (CH3), 31.6 (CH3), 43.7 (NCH2),
107.2, 116.5, 124.1, 140.7, 143.4, 146.1, 150.0 (Ar-C), 152.4,
154.7 (2C ¼ O). MS (EI): m/z 310 [Mþ]. Anal. (C15H14N6O2)
Calcd/Found: C, 58.06 (57.88); H, 4.55 (4.72); N, 27.08 (26.95).
2-(1,3-Dimethyl-2,6-dioxo-1,2,3,6-tetrahydropurin-7-yl)-N0-(1-
substituted phenylethylidene)acetohydrazide 5–15
A mixture of acetohydrazide 3 (0.005 mol) and the appropriate
aldehyde/or ketone derivative (0.0075 mol) was heated under
reflux in ethanol (50 ml) for 24 h. The reaction mixture was
concentrated in vacuum and the solid obtained was filtered, dried
and crystallized from acetic acid to give compounds 5–15.
5: 1H-NMR ꢀ: 1.31 (s, 3H, CH3), 2.75 (s, 6H, 2NCH3CO), 5.51
(s, 2H, NCH2CO), 7.20–7.76 (m, 5H, Ar-H), 8.11 (s, 1H,
N ¼ CH), 9.38 (brs, 1H, CONH). 13C NMR: ꢀ 13.6 (CH3),
28.8(CH3), 30.1(CH3), 32.6(NCH2), 107.8, 128.5, 129.6, 131.5,
135.2, 145.3, 150.7, 151.4 (Ar-C), 151.9, 154.2, 163.9 (3C ¼ O).
MS (EI): m/z 354 [Mþ]. Anal. (C17H18N6O3) Calcd/Found: C,
57.62 (57.81); H, 5.12 (5.37); N, 23.72 (23.92).
1
6: H-NMR ꢀ: 1.28 (s, 3H, CH3), 2.29 (s, 4H, Ar-CH3), 2.80
(s, 6H, 2NCH3CO), 5.52 (s, 2H, NCH2CO), 7.20–7.81 (m, 4H,
Ar-H), 8.11 (s, 1H, N ¼ CH), 9.20 (brs, 1H, CONH). 13C NMR: ꢀ
13.9 (CH3), 29.3 (CH3), 30.3 (CH3), 31.6 (CH2N), 107.9, 126.0,
129.1, 129.7, 131.6, 139.1, 145.9, 150.3, 151.8 (Ar-C), 154.6,
163.2, 165.8 (3C ¼ O). MS (EI): m/z 368 [Mþ]. Anal.
(C18H20N6O3) Calcd/Found: C, 58.69 (58.46); H, 5.47 (5.51);
N, 22.81 (23.01).
7: 1H-NMR ꢀ: 1.27 (s, 3H, CH3), 2.77 (s, 6H, 2NCH3CO), 5.52
(s, 2H, NCH2CO), 7.21–7.79 (m, 4H, Ar-H), 8.11 (s, 1H, N ¼ CH),
9.21 (brs, 1H, CONH). 13C NMR: ꢀ 13.6 (CH3), 29.5 (CH3), 30.2
(CH3), 32.5 (CH2N), 107.8, 127.6, 129.5, 130.8, 132.7, 135.1,
138.3, 146.1, 150.2, 151.5, 154.7 (Ar-C), 159.6, 162.9, 167.7
(3C ¼ O). MS (EI): m/z 388 [Mþ]. Anal. (C17H17ClN6O3) Calcd/
Found: C, 52.51 (52.77); H, 4.41 (4.64); N, 21.61 (21.57).
8: 1H-NMR ꢀ: 1.14 (s, 3H, CH3), 2.81 (s, 6H, 2NCH3CO), 5.52
(s, 2H, NCH2CO), 7.20–7.81 (m, 4H, Ar-H), 8.11 (s, 1H, N ¼ CH),
8.80 (brs, 1H, CONH). 13C NMR: ꢀ 13.5 (CH3), 29.3(CH3),
30.2(CH3), 32.7(CH2N), 108.7, 115.1, 117.6, 122.2, 129.7, 132.8,
145.6, 149.9, 151.2, 154.3, 158.2 (Ar-C), 154.5, 163.8, 167.2
(3C ¼ O). MS (EI): m/z 399 [Mþ]. Anal. (C17H17N7O5) Calcd/
Found: C, 51.13 (50.92); H, 4.29 (4.53); N, 24.55 (24.80).
9: 1H-NMR ꢀ: 1.05 (s, 3H, CH3), 1.39–1.61 (m, 11H,
cyclohexyl-H), 2.75 (s, 6H, 2NCH3CO), 4.74 (s, 2H, NCH2CO),
8.18 (s, 1H, N ¼ CH), 9.41 (br s, 1H, CONH). 13C NMR: ꢀ 19.0
(CH3), 25.2 (CH3), 26.0 (CH2), 28.0 (CH2), 36.5 (CH2), 47.3 (CH),
107.8, 147.8, 149.0, 150.8 (Ar-C), 152.4, 154.6, 167.2 (3C ¼ O).
MS (EI): m/z 360 [Mþ]. Anal. (C17H24N6O3) Calcd/Found: C,
56.65 (56.87); H, 6.71 (6.55); N, 23.32 (23.17).
8,10-Dimethyl-[1,2,5]triazepino[4,3,5-hi]purine-
3,9(2H,4H,8H,10H)-dione 16
The acid hydrazide 3 (0.001 mol) in glacial acetic acid (20 ml)
containing fused sodium acetate (1.0 g) was heated under
reflux for 24 h. The reaction mixture was cooled and the solid
separated was filtered, dried and crystallized from acetic acid
to obtain 16.
16: 1H-NMR ꢀ: 2.74 (s, 6H, 2NCH3CO), 4.63 (s, 2H,
NCH2CO), 7.31 (s, 1H, Ar-H), 7.55 (brs, 1H, NHCO). 13C NMR:
ꢀ 29.1 (CH3), 31.3 (CH3), 48.5 (CH2N), 111.3, 137.1, 137.8, 150.5
(Ar-C), 153.7, 164.8 (2C ¼ O). MS (EI): m/z 234 [M þ]. Anal.
(C9H10N6O2) Calcd/Found: C, 46.15 (45.92); H, 4.30 (4.61); N,
35.88 (36.07).

DOI: 10.3109/14756366.2013.795957
Synthesis and hypoglycemic activity of theophylline derivatives 447
NMR: ꢀ 29.3 (CH3), 30.0 (CH3), 32.5 (CH2N), 108.1, 126.0,
N-[2-(2 -(2-(1,3-Dimethyl-2,6-dioxo-1,2,3,6-tetrahydropurin-7-
yl)acetyl)-hydrazinecarbonyl)substitutedphenyl]benzamide 17–19 132.5, 133.2, 133.6, 146.3, 150.1 (Ar-C), 152.4, 154.5, 164.0,
164.3 (5C ¼ O). MS (EI): m/z 416 [Mþ]. Anal. (C17H13ClN6O5)
A mixture (0.00s mol) of equimolecular amount of 3 and the
Calcd/Found: C, 48.99 (49.26); H, 3.14; N (3.37), 20.16 (19.88).
appropriate benzoxazone derivative was heated under reflux for
24: 1H-NMR ꢀ: 2.74 (s, 6H, 2NCH3CO), 4.63 (s, 2H,
24 h in pyridine (30 ml). The reaction mixture was concentrated
NCH2CO), 7.96–8.56 (m, 4H, Ar-H), 8.80 (brs, 1H, NH). 13C
in vacuum and the solid obtained was crystallized from acetic acid
NMR: ꢀ 29.3 (CH3), 30.1 (CH3), 32.7 (CH2N), 108.5, 125.3,
to give 17–19.
127.8, 133.0, 133.2, 133.5, 145.8, 148.0, 150.3 (Ar-C), 153.4,
17: 1H-NMR ꢀ: 2.73 (s, 6H, 2NCH3CO), 4.65 (s, 2H,
154.9, 164.1, 164.3 (5C ¼ O). MS (EI): m/z 427 [Mþ]. Anal.
NCH2CO), 7.51–8.0 (m, 10H, Ar-H), 8.50 (brs, 3H, NH). 13C
(C17H13N7O7) Calcd/Found: C, 47.78 (47.94); H, 3.07 (2.75);
NMR: ꢀ 28.5 (CH3), 29.7 (CH3), 32.3 (CH2N), 108.0, 122.4,
N, 22.94 (23.19).
124.7, 126.1, 127.3, 129.6, 133.0, 134.6, 138.2, 146.6, 150.1
(Ar-C), 153.8, 155.2, 164.2, 164.5, 164.6 (5C ¼ O). MS (EI): m/z
N0-Acetyl-2-(1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxopurin-7-
yl)aceto-hydrazide 25–28
475 [Mþ]. Anal. (C23H21N7O5) Calcd/Found: C, 58.10 (57.93);
H, 4.45 (4.73); N, 20.62 (20.34).
18: 1H-NMR ꢀ: 2.71 (s, 6H, 2NCH3CO), 4.63 (s, 2H,
NCH2CO), 7.44–8.0 (m, 9H, Ar-H), 8.54 (brs, 3H, NH). 13C
NMR: ꢀ 28.4 (CH3), 29.7 (CH3), 32.3 (CH2N), 107.7, 121.9,
124.5, 127.3, 129.1, 132.5, 133.5, 138.0, 146.5, 150.3 (Ar-C),
153.7, 155.1, 164.2, 164.4, 164.5 (5C¼O). MS (EI): m/z 509
[Mþ]. Anal. (C23H20ClN7O5) Calcd/Found: C, 54.18 (54.37);
H, 3.95 (4.08); N, 19.23 (18.95).
19: 1H-NMR ꢀ: 1H-NMR ꢀ: 2.71 (s, 6H, 2NCH3CO), 4.62
(s, 2H, NCH2CO), 7.45–8.31(m, 9H, Ar-H), 8.51 (brs, 3H, NH).
13C NMR: ꢀ 28.7 (CH3), 29.5 (CH3), 32.2 (CH2N), 107.8, 121.0,
121.8, 123.7, 124.3, 128.0, 129.1, 132.6, 137.5, 141.2, 147.0,
150.2, 151.5 (Ar-C), 152.9, 154.0, 164.2, 164.3, 164.4 (5C ¼ O).
MS (EI): m/z 520 [Mþ]. Anal. (C23H20N8O7) Calcd/Found: C,
53.08 (53.31); H, 3.87 (3.69); N, 21.53 (21.77).
A mixture of the hydrazide 3 (0.005 mol) and the appropriate
acid chloride (0.0065 mol) in pyridine (15 ml) was heated under
reflux for 1 h. The solid obtained on cooling was crystallized from
ethanol to afford compounds 25–28 (Table 1).
25: 1H-NMR ꢀ: 2.25 (s, 3H, CH3CO), 2.77 (s, 6H, 2NCH3CO),
4.63 (s, 2H, NCH2CO), 8.09 (s, 1H, N ¼ CH). 13C NMR: ꢀ 24.6
(CH3), 28.2 (CH3), 29.5 (CH3), 32.4 (CH2), 107.8, 144.8, 150.8
(Ar-C), 152.0, 155.1, 164.3, 168.0 (4C ¼ O). MS (EI): m/z 294
[Mþ]. Anal. (C11H14N6O4) Calcd/Found: C, 44.90 (45.18);
H, 4.80 (5.11); N, 28.56 (28.86).
26: 1H-NMR ꢀ: 2.73 (s, 6H, 2NCH3CO), 3.36 (s, 2H, CH2CO),
4.70 (s, 2H, NCH2CO), 7.23–7.95 (m, 6H, Ar-H), 9.31 (br s, 2H,
CONHNHCO). 13C NMR: ꢀ 29.0 (CH3), 29.4 (CH3), 32.3
(NCH2), 43.3 (CH2), 107.9, 127.5, 129.1, 129.9, 135.9, 146.3,
150.8 (Ar-C), 152.2, 155.0, 164.3, 168.1 (4C ¼ O). MS (EI): m/z
370 [Mþ]. Anal. (C17H18N6O4) Calcd/Found: C, 55.13 (54.85);
H, 4.90 (5.17); N, 22.69 (22.90).
27: 1H-NMR ꢀ: 2.71 (s, 6H, 2NCH3CO), 4.70 (s, 2H,
NCH2CO), 7.59–8.01 (m, 6H, Ar-H), 9.30 (brs, 2H, 2CONH).
13C NMR: ꢀ 29.0 (CH3), 29.8 (CH3), 32.8 (CH2), 108.1, 129.2,
133.8, 135.4, 146.5, 150.3 (Ar-C), 152.1, 154.6, 162.5, 164.7
(4C ¼ O). MS (EI): m/z 356 [Mþ]. Anal. (C16H16N6O4) Calcd/
Found: C, 53.93 (54.21); H, 4.53 (4.27); N, 23.58 (23.74).
28: 1H-NMR ꢀ: 2.74 (s, 6H, 2NCH3CO), 4.72 (s, 2H,
NCH2CO), 7.67–8.08 (m, 4H, Ar-H), 9.31 (brs, 2H, 2CONH).
13C NMR: ꢀ 29.1 (CH3), 29.8 (CH3), 32.9 (CH2), 107.5, 129.1,
135.7, 137.2, 137.9, 146.9, 150.1 (Ar-C), 152.0, 154.7, 160.7,
164.6 (4C ¼ O). MS (EI): m/z 362 [Mþ]. Anal. (C14H14N6O4S)
Calcd/Found: C, 46.40 (46.68); H, 3.89 (4.11); N, 23.19 (22.95);
S, 8.85 (9.08).
2-(2-(1,3-Dimethyl-2,6-dioxo-1,2,3,6-tetrahydropurin-7-yl)ace-
tyl)-N-phenyl hydrazine carbothioamide 20
A mixture of the hydrazide 3 (0.005 mol) and phenylisothiocya-
nate (0.006 mol) in dioxane was heated under reflux for 24 h.
The reaction mixture was concentrated in vacuum and the solid
obtained was crystallized from acetic acid (Table 1).
20: 2.75 (s, 6H, 2NCH3CO), 4.63 (s, 2H, NCH2CO), 7.25–
8.11(m, 6H, Ar-H), 8.51 (m, 3H, NH). 13C NMR: ꢀ 28.8 (CH3),
29.1 (CH3), 32.1 (CH2N), 107.8, 123.6, 124.9, 129.7, 137.2,
145.2, 150.3, 151.5 (Ar-C), 152.5, 154.2, 164.5 (3 C ¼ O), 172.2
(C ¼ S). MS (EI): m/z 387 [Mþ]. Anal. (C16H17N7O3S) Calcd/
Found: C, 49.60 (49.32); H, 4.42 (4.19); N, 25.31 (25.09); S, 8.28
(8.05).
2-(1,3-Dimethyl-2,6-dioxo-1,2,3,6-tetrahydropurin-7-yl)-N-(sub-
stituted dioxo-heterocyclic-1/or 2-yl) acetamide 21–24
N0-(2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydropurin-7-yl)ace-
tyl)-4-substituted benzenesulfonohydrazide 29–31
A mixture of compound 3 (0.01 mol), the appropriate anhydride
(0.01 mol) and glacial acetic acid (30 ml), was heated under reflux
for 24 h. The precipitated solid was filtered while hot, dried and
crystallized from acetic acid to afford 21–24.
A mixture of the hydrazide 3 (0.005 mol) and the appropriate
benzenesulfonyl chloride (0.0065 mol) in pyridine (20 ml) was
heated under reflux for 3 h. The solvent was evaporated under
reduced pressure and the solid obtained was crystallized from
ethanol to afford compounds 29–31.
21: 1H-NMR ꢀ: 2.69 (s, 6H, 2NCH3CO), 2.76 (m, 4H,
2CH2CO), 4.69 (s, 2H, NCH2CO), 8.09 (s, 1H, N ¼ CH), 8.91
(s, 1H, NHCO). 13C NMR: ꢀ 29.0 (CH3), 30.2 (CH3), 30.7 (CH2),
32.0 (CH2), 107.9, 146.8, 150.7 (Ar-C), 151.3, 153.6, 164.6, 171.2
(5C ¼ O). MS (EI): m/z 334 [Mþ]. Anal. (C13H14N6O5) Calcd/
Found: C, 46.71 (46.54); H, 4.22 (4.51); N, 25.14 (24.98).
22: 1H-NMR ꢀ: 2.71 (s, 6H, 2NCH3CO), 4.60 (s, 2H,
NCH2CO), 7.64–8.10 (m, 5H, Ar-H), 8.25 (brs, 1H, NHCO).
13C NMR: ꢀ 29.1 (CH3), 29.9 (CH3), 32.4 (CH2N), 107.9, 128.0,
132.1, 132.9, 146.2, 150.2 (Ar-C), 152.5, 154.3, 164.2, 164.3
(5C ¼ O). MS (EI): m/z 382 [Mþ]. Anal. (C17H14N6O5) Calcd/
Found: C, 53.40 (53.61); H, 3.69 (3.85); N, 21.98 (22.07).
23: 1H-NMR ꢀ: 2.71 (s, 6H, 2NCH3CO), 4.61 (s, 2H,
NCH2CO), 7.76–8.01 (m, 4H, Ar-H), 8.27 (brs, 1H, NH). 13C
29: 1H-NMR ꢀ: 2.82 (s, 6H, 2NCH3CO), 4.95 (br s, 1H,
SO2NH), 4.66 (s, 2H, NCH2CO), 7.53–8.10 (m, 6H, Ar-H), 9.60
(br s, 1H, CONH). 13C NMR: ꢀ 29.0 (CH3), 29.7 (CH3), 32.0
(CH2), 107.6, 127.1, 129.4, 132.4, 139.5, 145.8, 150.2 (Ar-C),
151.3, 154.6, 165.3 (3C ¼ O). MS (EI): m/z 392 [Mþ]. Anal.
(C15H16N6O5S) Calcd/Found: C, 45.91 (46.08); H, 4.11 (4.35);
N, 21.42 (21.77); S, 8.17 (8.41).
1
30: H-NMR ꢀ: 2.72 (s, 6H, 2NCH3CO), 2.85 (s, 3H, CH3),
4.94 (br s, 1H, SO2NH), 4.64 (s, 2H, NCH2CO), 7.52–8.10 (m,
5H, Ar-H), 9.61 (br s, 1H, CONH). 13C NMR: ꢀ 25.3 (CH3), 29.1
(CH3), 29.8 (CH3), 32.3 (CH2), 107.5, 127.4, 129.6, 137.1, 141.2,
145.7, 150.3 (Ar-C), 151.1, 154.5, 164.7 (3C ¼ O). MS (EI): m/z

448 A. M. Alafeefy et al.
J Enzyme Inhib Med Chem, 2014; 29(3): 443–448
406 [Mþ]. Anal. (C16H18N6O5S) Calcd/Found: C, 47.28 (46.99);
H, 4.46 (4.68); N, 20.68 (20.39); S, 7.89 (8.08).
5. Buxton DB, Fisher RA, Robertson SM, Olson MS. Stimulation of
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6. Mclane MP, Black PR, Law WR, Raymond RM. Adenosine reversal
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31: 1H-NMR ꢀ: 2.70 (s, 6H, 2NCH3CO), 4.90 (br s, 1H,
SO2NH), 4.65 (s, 2H, NCH2CO), 7.55–8.01 (m, 5H, Ar-H), 9.60
(br s, 1H, CONH). 13C NMR: ꢀ 29.0 (CH3), 29.9 (CH3), 32.5
(CH2), 107.6, 122.0, 128.1, 145.9, 150.2, 152.0 (Ar-C), 152.1,
154.6, 164.5 (3C ¼ O). MS (EI): m/z 437 [Mþ]. Anal.
(C15H15N7O7S) Calcd/Found: C, 41.19 (40.88); H, 3.46 (3.72);
N, 22.42 (22.15); S, 7.33 (7.06).
9. Camaioni E, Costanzi S, Vittori S, et al. New substituted
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Evaluation of serum glucose level
Diabetes model was induced by a single intraperitonial injection
of streptozotocin at a dosage of 70 mg/kg22. Streptozotocin-
injected animals were given 20% glucose solution for 24 h to
prevent initial drug-induced hypoglycemic mortality. Three days
after streptozotocin administration, the blood glucose level of
each rat was determined. Rats with blood glucose levels4350 mg/
dL were considered diabetic and included in the present study.
Diabetic animals were randomly divided into three main groups
(N ¼ 6 animals/group): untreated (received 1% CMC), treated
with test compounds (10 mg/kg/day) or treated with a positive
control (glibenclamide, 10 mg/kg/day). The experiment included
also a healthy group received equal amounts of 1% CMC as a
vehicle and served as a control group. All treatments were by
gavages over a period of 14 days.
During this period, the animals were kept on food and water
given ad libitum. Parameters such as changes in body weight, food
intake, water intake and mortality were recorded. At the end of
treatment the rats were fasted for 12 h and blood samples were
collected from the retro-orbital plexus then serum was separated.
Serum glucose level was determined using Randox Laboratories
LTD kits on Shimadzu UV-1202 Spectrophotometer according to
the manufacturers’ instructions.
13. Katyal J, Gupta YK. Dopamine release is involved in antinociceptive
effect of theophylline. Int J Neurosci 2012;122:17–21.
´
14. Hierrezuelo J, Manuel Lopez-Romero J, Rico R, et al. Synthesis of
theophylline derivatives and study of their activity as antagonists at
adenosine receptors. Bioorg Med Chem 2010;18:2081–8.
15. Watanabe S, Yamakami J, Tsuchiya M, et al. Anti-inflammatory
effect of theophylline in rats and its involvement of the
glucocorticoid-glucocorticoid receptor system. J Pharmacol Sci
2008;106:566–70.
16. Hasegawa M, Hada J, Abe T, et al. Theophylline attenuates
hippocampal blood flow responses induced by tooth pulp stimula-
tion in rats. Neurosci Res 2009;65:156–9.
Declaration of interest
´
17. Cunha RA, Ferre S, Vaugeois JM, Chen JF. Potential therapeutic
interest of adenosine A2A receptors in psychiatric disorders. Curr
Pharm Des 2008;14:1512–24.
18. Umrani DN, Goyal RK. Beneficial effects of fenoldopam treatment
on renal function in streptozotocin-induced diabetic rats. Clin Exp
Hypertens 2002;24:207–19.
19. Akhani SP, Vishwakarma SL, Goyal RK. Anti-diabetic activity of
Zingiber officinale in streptozotocin-induced type I diabetic rats.
J Pharm Pharmacol 2004;56:101–5.
20. Majithiya JB, Balaraman R. Metformin reduces blood pressure and
restores endothelial function in aorta of streptozotocin-induced
diabetic rats. Life Sci 2006;78:2615–24.
The authors extend their appreciation to the Deanship of Scientific
Research at King Saud University for funding the work through the
research group project No. RGP-VPP-060.
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