Synthesis and biological evaluation of some 2,4,5-trisubstituted thiazole derivatives as potential antimicrobial and anticancer agents

Article abstract of DOI:10.1002/ardp.200800026

We report on the synthesis and biological evaluation of two series of 2,4,5-polysubstituted thiazoles comprising the acid hydrazide functionality and some derived pharmacophores known to contribute to various chemotherapeutic activities. All newly synthesized compounds were subjected to in-vitro antibacterial and antifungal screening. Of the compounds tested, 13 derivatives displayed inhibitory effect on the growth of three Gram-positive strains while they lack activity against Gram-negative bacteria. Moreover, four compounds were able to exert antifungal activity against C. albicans. Potential antibacterial and antifungal activities were linked to the thiosemicarbazide function 6a-f and those substituted with both the thioureido and thiosemicarbazide moieties 12a-f. Compounds 6f and 12f (R = 4-F-C₆H₄) could be considered as the most active members in this investigation with a broad spectrum of antibacterial activity against three types of Gram-positive bacteria, together with an appreciable antifungal activity against C. albicans. Compounds 6d, 6f, and 12f were twice as active as ampicillin against B. subtilis. The best antifungal activity was shown by compound 6d 50% less active than clotrimazole. 17 compounds were selected and tested for their preliminary in-vitro anticancer activity according to the current one-dose protocol of the NCI. Three cell lines, non-small cell lung cancer Hop-92, ovarian cancer IGROV1, and melanoma SK-MEL-2, exhibited some sensitivity against most of the tested compounds. Compound 12f proved to be the most active anticancer member with a broad spectrum of activity against most of the tested subpanel tumor cell lines. Consequently, 12f was carried over to be tested in the five-dose assay.

Full text of DOI:10.1002/ardp.200800026

424
Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
Full Paper
Synthesis and Biological Evaluation of Some 2,4,5-
Trisubstituted Thiazole Derivatives as Potential Antimicrobial
and Anticancer Agents
Mohammed S. Al-Saadi, Hassan M. Faidallah, and Sherif A. F. Rostom
Department of Medicinal Chemistry, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
We report on the synthesis and biological evaluation of two series of 2,4,5-polysubstituted thia-
zoles comprising the acid hydrazide functionality and some derived pharmacophores known to
contribute to various chemotherapeutic activities. All newly synthesized compounds were sub-
jected to in-vitro antibacterial and antifungal screening. Of the compounds tested, 13 derivatives
displayed inhibitory effect on the growth of three Gram-positive strains while they lack activity
against Gram-negative bacteria. Moreover, four compounds were able to exert antifungal activ-
ity against C. albicans. Potential antibacterial and antifungal activities were linked to the thiose-
micarbazide function 6a–f and those substituted with both the thioureido and thiosemicarba-
zide moieties 12a–f. Compounds 6f and 12f (R = 4-F-C6H4) could be considered as the most active
members in this investigation with a broad spectrum of antibacterial activity against three
types of Gram-positive bacteria, together with an appreciable antifungal activity against C. albi-
cans. Compounds 6d, 6f, and 12f were twice as active as ampicillin against B. subtilis. The best
antifungal activity was shown by compound 6d 50% less active than clotrimazole. 17 com-
pounds were selected and tested for their preliminary in-vitro anticancer activity according to
the current one-dose protocol of the NCI. Three cell lines, non-small cell lung cancer Hop-92,
ovarian cancer IGROV1, and melanoma SK-MEL-2, exhibited some sensitivity against most of the
tested compounds. Compound 12f proved to be the most active anticancer member with a
broad spectrum of activity against most of the tested subpanel tumor cell lines. Consequently,
12f was carried over to be tested in the five-dose assay.
Keywords: Acid hydrazides / Antibacterial / Anticancer activity / Antifungal / Thiazoles /
Received: January 26, 2008; accepted: April 4, 2008
DOI 10.1002/ardp.200800026
pathogenic bacteria resistant to currently marketed anti-
Introduction
bacterial agents has reached an alarming level in many
countries [1]. Moreover, there has been a rapid spread in
primary and opportunistic fungal infections because of
the increased number of immunocompromised patients
(AIDS, cancer, and transplants). Candida albicans is one of
the most common opportunistic fungi responsible for
such type of infections [2]. Infections caused by these
microorganisms pose a serious challenge to the medical
community and highlight the importance and urgent
need for new, more potent and selective non-traditional
antimicrobial agents. On the other hand, chemotherapy
is, at present, the only effective therapy for some types of
disseminated cancers [3]. Consequently, great expecta-
The past few years have witnessed an obvious reduction
in the mortality caused by infectious diseases and a rise
in the control of neoplastic pathologies. Nevertheless,
the emergence of Gram-positive and Gram-negative
Correspondence: Prof. Sherif A. F. Rostom, Ph.D., Associate Professor
of Medicinal Chemistry, Department of Medicinal Chemistry, Faculty of
Medicine, King Abdulaziz University, P.O. Box 80205, Jeddah 21589,
Saudi Arabia.
E-mail: sherifrostom@yahoo.com
Fax: +966 2-6400000-22327
Abbreviations: inhibition zones (IZ)
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
Substituted Thiazoles as Antimicrobial, Anticancer Agents
425
Reagents, conditions, and yields: i: (CH3CO)2O, warming, 83%; ii: H2NNH2.H2O, ethanol, reflux, 70%; iii: Aldehyde, acetic acid, reflux, 38 – 83%;
iv: Substituted isocyanate, pyridine, reflux, 86 – 90%; v: Substituted isothiocyanate, pyridine, reflux, 38 – 82%; vi: HCOOH, reflux, 90%; vii: 4-substi-
tuted benzenesulfonyl chloride, pyridine, reflux, 39 – 61%.
Scheme 1. Synthesis of the target compounds 2–8.
tion is attached to the future development of novel use in designing new potent and selective chemothera-
potent and more selective anticancer agents. Among vari- peutic agents, we have reported the synthesis and in-vitro
ous heterocycles that have been explored for developing antimicrobial [25] and anticancer evaluation of some pol-
pharmaceutically important molecules, thiazoles, fused ysubstituted thiazole-containing compounds [26–30].
thiazoles, and thiazoles linked to various heterocylic Some derivatives showed promising broad-spectrum
rings through different linkages have recently attracted antimicrobial and antitumor activities. In view of these
great attention. They were found to be associated with a facts, and as a continuation of our previous efforts, a new
wide range of chemotherapeutic activities including series of 2,4,5-trisubstituted thiazoles has been synthe-
antimicrobial [4–7], antifungal [8, 9], antiparasitic [10], sized in the hope of discovering more active and selective
and antiviral [11, 12] activities. On the other hand, thia- antimicrobial and/or anticancer agents. The pattern of
zole-containing compounds were reported to contribute substitution of the newly designed compounds focussed
to a variety of anticancer potentials including antitumor on the acid hydrazide group and some derived function-
[13, 14], cytotoxic [15, 16], antiproliferative [17, 18], DNA- alities such as the ureido, thioureido, sulfonamido, N-
cleaving [19, 20], and angiogenesis inhibiting [21] activ- formyl, N-acetyl, semicarbazide, and thiosemicarbazide
ities. Interest in the chemotherapeutic activity of thia- groups based on the reported facts about their role in
zoles was potentiated after the discovery of the natural exerting potential chemotherapeutic activities [13, 14,
antineoplastic antibiotics tiazofurin [22, 23], bleomycin, 31 ,32]. The synthesis of some Schiff' bases was not far of
netropsin, and thiazole netropsin [24]. Most of these nat- our interest, owing to their effective contribution as
ural drugs have the thiazole carboxamide moiety as a potential chemotherapeutic agents [33–35]. The varia-
common feature.
tion in the nature and size of substituents at such func-
As a part of an ongoing research program on studying tionalities was thought to be of interest representing var-
the synthesis and biological properties of some heterocy- iable electronic, lipophilic, and steric environment that
clic compounds as novel structure leads that might be of would influence the targeted biological activities.
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

426
M. S. Al-Saadi et al.
Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
Reagents, conditions, and yields: i: H2NNH2.H2O, ethanol, reflux, 67%; ii: (CH3CO)2O, warming, 73%; iii: Substituted isocyanate, pyridine,
reflux,78 – 95%; iv: Substituted isothiocyanate, pyridine, reflux, 29-95%.
Scheme 2. Synthesis of the target compounds 9–12.
stituted ureido)-4-methylthiazole-5-carbonyl)semicarba-
Results and discussion
zides 11a, b and their isosteric 4-substituted-1-(2-(N-substi-
tuted thioureido)-4-methylthiazole-5-carbonyl)thiosemi-
carbazides 12a–f could be achieved by condensing the
acid hydrazide 9 with two moles of the appropriate iso-
cyanates or isothiocyanates, respectively.
Chemistry
The synthetic pathways to obtain the intermediate and
target compounds in this study are depicted in
Schemes 1 and 2. In Scheme 1, the starting ethyl 2-
amino-4-methylthiazole-5-carboxylate 1 [36] was warmed
with acetic anhydride to produce the ethyl 2-acetamido-
4-methylthiazole-5-carboxylate 2 in a good yield. When 2
was reacted with hydrazine hydrate, the 2-acetamido-4-
Antimicrobial screening
All the newly synthesized compounds 2–12 were eval-
uated for their in-vitro antibacterial activity against Staph-
ylococcus aureus (ATCC 6538), Bacillus subtilis (NRRL B-
14819), and Bacillus cereus (ATCC 14579) as examples of
Gram-positive bacteria and Escherichia coli (ATCC 25922),
Pseudomonas aeruginosa (ATCC 27853), and Klebsiella pneu-
monia (clinical isolate) as examples of Gram-negative bac-
teria. They were also evaluated for their in-vitro antifun-
gal potential against Candida albicans (ATCC 10231) and
Aspergillus niger (recultured) fungal strains. Agar-diffu-
sion method was used for the determination of the pre-
liminary antibacterial and antifungal activity. Ampicil-
lin trihydrate and clotrimazole were used as reference
drugs. The results were recorded for each tested com-
pound as the average diameter of inhibition zones (IZ) of
bacterial or fungal growth around the discs in mm. The
minimum inhibitory concentration (MIC) measurement
was determined for compounds that showed significant
growth inhibition zones (F14 mm) using the two-fold
serial dilution method [37]. The IZ (mm) and MIC (lg/mL)
values are recorded in Table 1.
methylthiazole-5-carboxylic acid hydrazide
3
was
obtained, which was employed as the key intermediate
in this part. Condensing 3 with the appropriate aromatic
or heterocyclic aldehyde gave rise to the corresponding
arylidine derivatives 4a–h. Reacting the acid hydrazide 3
with different isocyanates and isothiocyanates in pyri-
dine, afforded the corresponding 4-substituted-1-(2-acet-
amido-4-methylthiazole-5-carbonyl)semicarbazides 5a, b
and the analogous 4-substituted thiosemicarbazides 6a–
f, respectively. Furthermore, refluxing 3 in formic acid
gave the target N-formyl-2-acetamido-4-methylthiazole-5-
carboxylic acid hydrazide 7. On the other hand, reacting
3 with benzenesulfonyl chloride or p-toluenesulfonyl
chloride in the presence of pyridine led to the formation
of the N-substituted benzenesulfonyl-2-acetamido-4-
methylthiazole-5-carboxylic acid hydrazides 8a, b.
At this stage, it was designed to synthesize the target
carboxylic acid hydrazide 9 from the starting thiazole
ester 1 and hydrazine hydrate. Acetylation of 9 with ace-
tic anhydride furnished the N-acetyl-2-acetamido-4-meth-
ylthiazole-5-carboxylic acid hydrazide 10. Finally, the syn-
thesis of the target compounds 4-substituted-1-(2-(N-sub-
The results revealed that 13 out of the tested 31 com-
pounds displayed an obvious inhibitory effect on the
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
Substituted Thiazoles as Antimicrobial, Anticancer Agents
427
Table 1. Inhibition zone (IZ) diameters (in mm) and minimal inhibitory concentrations (MIC, lg/mL) of the active newly synthesized
compounds.
Compound
S. aureus
B. subtilis
B. cereus
C. albicans
ATCC 6538
NRRL B-14819
ATCC 14579
ATCC 10231
IZ
MIC
IZ
MIC
IZ
MIC
IZ
MIC
a)
4g
5a
5b
6d
6f
–
–
25
50
16
–
–
20
20
10
–
–
–
–
16
14
19
30
–
25
–
–
6.25
6.25
NT
–
–
–
–
25
50
6.25
12.5
–
–
–
–
13
21
–
–
–
–
–
9
–
20
32
–
–
–
–
–
–
–
19
18
18
–
–
–
–
–
–
20
17
21
20
14
22
16
18
14
19
16
15
36
–
6.25
6.25
100
12.5
50
12.5
25
12.5
12.5
25
NTb)
25
–
12.5
25
100
–
–
–
9
11a
11b
12a
12b
12d
12e
12f
Ac)
–
–
–
–
NT
–
50
12.5
–
–
–
12
10
19
NT
42
NT
NT
25
NT
6.25
6.25
–
Cd)
a)
(–): totally inactive (no inhibition zone).
NT: Not tested.
A: Ampicillin trihydrate (Standard broad spectrum antibiotic).
C: Clotrimazole (Standard broad spectrum antifungal agent).
b)
c)
d)
growth of the tested Gram-positive strains while they that four analogs namely 6d, 6f, 9, and 12f were able to
were totally inactive against the three tested strains of produce appreciable growth inhibitiory activity against
Gram-negative bacteria. Moreover, four compounds were C. albicans (MIC values 12.5, 25, 25 and 100 lg/mL, respec-
able to exert variable degree of antifungal activity tively) comparable to that of clotrimazole (MIC 6.25 lg/
against C. albicans, whereas all of the tested compounds mL), the standard antifungal agent utilized in this assay
lacked antifungal activity against Asp. niger fungus.
As concerns the antibacterial potency of the active
(Table 1).
A deep insight into the structures of the active com-
compounds against S. aureus, compounds 6d and 6f were pounds revealed that the tested compounds belong to
equipotent to ampicillin (MIC 6.25 lg/mL), whereas the two main structure series namely; N-substituted 2-acet-
analogs 11a, 12a, 12d, and 12e (MIC 12.5 lg/mL) were 50% amido-4-methylthiazole-5-carboxylic acid hydrazides 3–
less active than that of ampicillin. Moreover, compounds 8 (Scheme 1) and the N-substituted 2-(substituted amino)-
5a, 12b, and 12f (MIC 25 lg/mL) showed 25% of the activ- 4-methylthiazole-5-carboxylic acid hydrazides 9–12
ity of ampicillin. With regard to the activity against Bacil- (Scheme 2).
lus subtilis, potential activity was displayed by com-
Within the first series (Scheme 1), the nature of the
pounds 6d, 6f, and 12f (MIC 6.25 lg/mL), which were substituent at the acid hydrazide functionality seems to
twice as active as ampicillin (MIC 12.5 lg/mL). The ana- manipulate the antimicrobial activity. Although the pro-
logs 4g and 12d (MIC 25 lg/mL) displayed half the totype 3 was totally inactive against all the tested micro-
potency of ampicillin, meanwhile, compound 12e (MIC organisms, the azomethins 4a–h showed weak antimi-
50 lg/mL) showed 25% of the potency of ampicillin (MIC crobial activity. Among these, compound 4g (R = 1-piperi-
12.5 lg/mL) against the same organism. Bacillus cereus dinyl) was the most active member, especially against the
proved to be the least sensitive Gram-positive microor- B. subtilis. Furthermore, derivatization of 3 into the 4-sub-
ganism to most of the tested compounds. Only two com- stituted semicarbazides resulted in two active com-
pounds, namely 6f (MIC 25 lg/mL) and 12f (MIC 50 lg/ pounds, namely 5a (R = cyclo-C6H11) and 5b (R = C6H5),
mL), exhibited remarkable growth inhibitory effect active against S. aureus (MIC values of 25 and 50 lg/mL,
towards B. cereus with MIC values of 25 and 50 lg/mL, respectively). On the other hand, the formation of the
respectively (Table 1). On the other hand, investigation of bioisosteric thiosemicarbazides 6a–f resulted in a notica-
the antifungal activity of the tested compounds revealed ble improvement in the spectrum of antimicrobial activ-
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

428
M. S. Al-Saadi et al.
Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
ity. Substitution of the thiosemicarbazide group with and 12f were selected by the National Cancer Institute
alkyl or aralkyl moieties led to the formation of weakly (NCI) in-vitro disease-oriented human cells screening
active compounds 6a–c. On the contrary, aryl substitu- panel assay to be evaluated for their in-vitro antitumor
ents, as in compounds 6d–f, showed obviously better activity. Effective one-dose assay has been added to the
antibacterial and antifungal activities. Therefore, com- NCI 60 Cell screen in order to increase compound
pound 6d (R = C6H5) showed high antibacterial activity throughput and reduce data-turnaround time to suppli-
against S. aureus and B. subtilis bacteria (MIC 6.25 lg/mL), ers while maintaining efficient identification of active
in addition to a good antifungal activity against C. albi- compounds [38–40]. All compounds submitted to the
cans (MIC 12.5 lg/mL). Substituting the phenyl moiety at NCI 60 Cell screen are now tested initially at a single high
position-4 with an electron-donating group (6e; R = 4-CH3- dose (10, lM) in the full NCI 60 cell panel including leuke-
C6H4), resulted in a dramatic reduction in activity against mia, non-small cell lung, colon, CNS, melanoma, ovarian,
all the tested organisms. Whereas maximum activity renal, prostate, and breast cancer cell lines. Only com-
within this series was obtained by introducing an elec- pounds which satisfy pre-determined threshold inhibi-
tron-withdrawing group at position-4 of the phenyl moi- tion criteria would progress to the five-dose screen. The
ety (6f; R = 4-F-C6H4) as evidenced by its MIC values, espe- threshold inhibition criteria for progression to the five-
cially against S. aureus and B. subtilis bacteria (MIC 6.25 dose screen was designed to efficiently capture com-
and 12.5 lg/mL, respectively).
pounds with anti-proliferative activity and is based on
Regarding the second series (Scheme 2), the key inter- careful analysis of historical Development Therapeutic
mediate acid hydrazide 9 showed weak antimicrobial Program (DTP) screening data. The data are reported as a
activity against S. aureus, B. subtilis, and C. albicans. Acety- mean graph of the percent growth of treated cells, and
lation of 9 to the 2-acetamido-N-acetyl-4-methylthiazole- presented as percentage growth inhibition (GI%) caused
5-carboxylic acid hydrazide 10 led to complete abolish- by the test compounds (Table 2).
ment of the antimicrobial activity. On the other hand,
The obtained data revealed that some of the tested sub-
converting the parent hydrazide 9 to the 4-substituted-2- panel tumor cell lines exhibited pronounced sensitivity
(N-substituted ureido)-4-methylthiazol-5-carbonyl]semi- profiles against most of the tested compounds. Among
carbazide derivatives furnished two compounds 11a (R = these, the non-small cell lung cancer Hop-92 cell line
cyclo-C6H11) and 11b (R = C6H5), active against S. aureus exhibited a variable degree of sensitivity towards 14 out
(MIC 12.5 and 50 lg/mL, respectively). Finally, bioisos- of the 17 compounds selected, with particular sensitivity
teric replacement of the ureido and semicarbazide func- towards compounds 3 and 12f (percentage growth inhib-
tionalities with the corresponding thioureido and thiose- ition 96.2 and 80.2%, respectively). Furthermore, the
micarbazide groups, resulted in a series of broad spec- growth of the melanoma SK-MEL-2 cell line was variably
trum potentially active compounds 12a–f. Unlike com- affected by the presence of the 17 tested compounds. Par-
pounds 6a–f, aliphatic-substituted compounds 12a and ticular high activities against this cell line were shown
12b (R = CH3 and cyclo-C6H11, respectively) exhibited good by compounds 3, 4d, 4g, 8a, and 12f with percentage
activity against S. aureus (MIC 12.5 and 25 lg/mL, respec- growth inhibition values of 75.3, 80.7, 84.7, 97.1, and
tively). Replacing the aliphatic substituent with an aryl 96.8%, respectively. In addition, the growth of the ovar-
counterpart 12d–f, led to an increase in the antimicro- ian cancer IGROV1 cell line was found to be inhibited by
bial potential and spectrum. The 4-fluorophenyl moiety eleven out of the tested compounds. This cell line was
(12f; R = 4-F-C6H4) proved to be the most favourable sub- clearly sensitive to compounds 4e, 4g, 7, 8a, and 10 with
stituent among this series. Compound 12f exhibited percentage growth inhibition values of 84.3, 90.8, 87.0,
broad spectrum antibacterial potential against S. aureus, 90.7, and 76.5%, respectively. It is worth-mentioning
B. subtilis, and B. Cereus (MIC 25, 6.25, and 50 lg/mL, that, only four compounds, namely; 3, 5b, 6c, and 12f
respectively), in addition to a moderate antifungal activ- were mildly able to inhibit the growth of the prostate
ity against C. albicans (MIC 25 lg/mL). On the other hand, cancer PC-3 cell line with percentage growth inhibition
compounds 12d (R = C6H5) and 12e (R = 4-CH3-C6H4) range of 14.8–47.9%. The rest of the tested tumor cell
showed promising antibacterial activity against S. aureus lines showed very weak or no sensitivity towards the
and B. subtilis together with weak antifungal activity, tested compounds (percentage growth inhibition range 0
when compared with 12f.
to a20%).
Further interpretation of the results revealed that com-
Preliminary in-vitro anticancer screening
pound 12f proved to be the most active member in this
Out of the newly synthesized compounds, 17 derivatives study with a broad spectrum of activity against most of
namely; 3, 4a, d–h, 5a, b, 6c, f, 7a, 8a, 10, 11a, b, 11d–h, the tested subpanel tumor cell lines, with particular
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
Substituted Thiazoles as Antimicrobial, Anticancer Agents
429
Table 2. In-vitro percentage growth inhibition (GI%) caused by the test compounds against some selected tumor cell lines at the
single-dose assay.a)
Compound
NSC No.
745904
Panel
Subpanel tumor cell lines (% growth inhibitory activity)
3
Non-Small Cell Lung Cancer
Leukemia
HOP-92 (96.2)
K-562 (32.8)
Melanoma
SK-MEL-2 (75.3)
Prostate Cancer
Non-Small Cell Lung Cancer
Breast Cancer
Ovarian Cancer
Leukemia
PC-3 (15.6)
4a
745905
HOP-92 (71.2), NCI – H522 (57.7)
MDA-MB-468 (55.0)
IGROV1 (32.5)
PRMI-8226 (45.5)
SK-MEL-2 (61.4)
Melanoma
4d
4e
745906
745907
Non-Small Cell Lung Cancer
Breast Cancer
Leukemia
HOP-92 (57.4)
T-47D (32.2)
PRMI-8226 (38.1)
SK-MEL-2 (80.7)
HOP-92 (46.3)
Melanoma
Non-Small Cell Lung Cancer
Ovarian Cancer
Leukemia
IGROV1 (84.3)
K-562 (41.3)
Melanoma
SK-MEL-2 (65.6)
4f
745908
745909
745910
Non-Small Cell Lung Cancer
Leukemia
Melanoma
Colon Cancer
Ovarian Cancer
Melanoma
Non-Small Cell Lung Cancer
Ovarian Cancer
Melanoma
HOP-92 (43.9)
K-562 (45.5)
SK-MEL-2 (56.4)
HCC – 2998 (79.7), HCT-116 (44.2)
IGROV1 (90.8)
SK-MEL-2 (84.7)
HOP-92 (51.6), NCI – H522 (74.8)
IGROV1 (29.7)
4g
4h
SK-MEL-2 (65.9)
5a
5b
745911
745912
Non-Small Cell Lung Cancer
Melanoma
Non-Small Cell Lung Cancer
Breast Cancer
NCI – H522 (61.5)
SK-MEL-2 (22.6)
HOP-92 (39.4), NCI – H226 (92.8), NCI – H522 (35.5)
MDA-MB-468 (38.7)
SK-MEL-2 (70.1)
Melanoma
Prostate Cancer
Non-Small Cell Lung Cancer
Breast Cancer
PC-3 (14.8)
HOP-92 (68.5)
6c
745913
MDA-MB-468 (50.0)
CCRF-CEM (38.7), K-562 (63.8), MOLT-4 (40.7), PRMI-8226 (69.7),
SR (47.9)
Leukemia
Renal Cancer
Melanoma
Prostate Cancer
Non-Small Cell Lung Cancer
Ovarian Cancer
Leukemia
ACHN (42.5), UO-31 (45.4)
LOX IMVI (33.8), SK-MEL-2 (69.2), UACC-62 (45.8)
PC-3 (16.3)
HOP-92 (48.6)
IGROV1 (27.3)
PRMI-8226 (64.1)
SK-MEL-2 (47.3), UACC-62 (39.8)
HOP-92 (32.8)
IGROV1 (87.0)
K-562 (45.2)
6f
7
745914
745916
Melanoma
Non-Small Cell Lung Cancer
Ovarian Cancer
Leukemia
Melanoma
SK-MEL-2 (37.3)
8a
10
745917
745915
Colon Cancer
Ovarian Cancer
Melanoma
Non-Small Cell Lung Cancer
Ovarian Cancer
Leukemia
HCT-116 (49.7)
IGROV1 (90.7)
SK-MEL-2 (97.1)
HOP-92 (42.5)
IGROV1 (76.5)
K-562 (38.6)
Melanoma
SK-MEL-2 (64.7)
11a
745921
Non-Small Cell Lung Cancer
Breast Cancer
Ovarian Cancer
Leukemia
Melanoma
CNS Cancer
HOP-92 (33.3)
MDA-MB-468 (65.5)
IGROV1 (29.4)
PRMI-8226 (45.4), SR (69.0)
SK-MEL-2 (17.8), M14 (32.6)
SNB-75 (38.8)
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

430
M. S. Al-Saadi et al.
Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
Table 2. Continued
Compound
NSC No.
Panel
Subpanel tumor cell lines (% growth inhibitory activity)
11b
745922
745923
Non-Small Cell Lung Cancer
Ovarian Cancer
Renal Cancer
Melanoma
Non-Small Cell Lung Cancer
HOP-92 (38.3)
IGROV1 (39.6)
UO-31 (40.3)
SK-MEL-2 (47.1)
12f
A 549 / ATCC (33.8), EKVX (36.8), HOP-92 (80.2), NCI – H226 (39.3),
NCI – H23 (62.0), NCI – H522 (66.1)
HCC – 2998 (31.6), HCT-116 (55.1), HCT-15 (38.1), HT29 (38.1)
MDA-MB-468 (55.5), T-47D (64.4)
IGROV1 (48.3), OVCAR-3 (43.4), OVCAR-3 (57.2)
CCRF-CEM (60.0), HL-60 (TB) (51.7), K-562 (48.6), MOLT-4 (63.5)
A498 (46.4), ACHN (34.7), TK-10 (56.5), UO-31 (61.3)
M14 (49.0), SK-MEL-2 (96.8), SK-MEL-5 (51.3), UACC-62 (63.1)
DU-145 (18.0), PC-3 (47.9)
Colon Cancer
Breast Cancer
Ovarian Cancer
Leukemia
Renal Cancer
Melanoma
Prostate Cancer
CNS Cancer
SF-295 (59.4), U251 (47.0)
a)
The data obtained from NCI's in vitro disease-oriented human tumor cell screen at 10 lM conc.
Table 3. Physicochemical and analytical data for compounds 2–12.
Compound
R or X
Yield (%)
M.p. (8C) (Crystallization Sol- Molecular Formula (Mol.
vent (s))*
Weight)a)
2
3
–
–
83
70
83
65
73
67
58
43
38
50
86
90
38
53
47
69
82
71
90
61
39
67
73
95
78
40
95
29
85
65
83
220–222 (E)
170–171 (E)
208–209 (A/W)
156–158 (E)
214–216 (E)
220–221 (A/W)
168–169 (E)
160–162 (E/W)
158–160 (E/W)
154–156 (E/W)
162–163 (E)
200–201 (E)
190–192 (E)
166–168 (E)
136–137 (M)
120–122 (E)
158–159 (E)
148–150 (E)
224–226 (E/W)
180–182 (A)
148–149 (A)
142–144 (M)
172–173 (E/W)
161–163 (E)
228–230 (E)
200–202 (E/PE)
204–206 (E)
142–144 (DMF/E)
138–140 (D/W)
156–158 (D/W)
187–189 (DMF/W)
C9H12N2O3S (228.27)
C7H10N4O2S (214.24)
C14H13ClN4O2S (336.80)
C15H16N4O2S (316.38)
C15H16N4O3S (332.38)
C12H12N4O2S2 (308.38)
C12H12N4O3S (292.31)
C13H15N5O2S (305.36)
C13H19N5O2S (309.39)
C12H17N5O3S (311.36)
C14H21N5O3S (339.41)
C14H15N5O3S (333.37)
C9H13N5O2S2 (287.36)
C14H21N5O2S2 (355.48)
C15H17N5O2S2 (363.46)
C14H15N5O2S2 (349.43)
C15H17N5O2S2 (363.46)
C14H14FN5O2S2 (367.42)
C8H10N4O3S (242.26)
C13H14N4O4S2 (354.40)
C14H16N4O4S2 (368.43)
C5H8N4OS (172.21)
C9H12N4O3S (256.28)
C19H30N6O3S (422.54)
C19H18N6O3S (410.45)
C9H14N6OS3 (318.44)
C19H30N6OS3 (454.68)
C21H22N6OS3 (470.63)
C19H18N6OS3 (442.58)
C21H22N6OS3 (470.63)
C19H16F2N6OS3 (478.56)
4a
4b
4c
4d
4e
4-Cl-C6H4
4-CH3-C6H4
4-OCH3-C6H4
2-thienyl
2-furyl
1-methylpyrrol-2-yl
1-piperidinyl
1-morpholinyl
cyclo-C6H11
C6H5
4f
4g
4h
5a
5b
6a
6b
6c
6d
6e
6f
CH3
cyclo-C6H11
CH2-C6H5
C6H5
4-CH3-C6H4
4-F-C6H4
–
H
CH3
–
–
cyclo-C6H11
C6H5
CH3
cyclo-C6H11
CH2-C6H5
C6H5
4-CH3-C6H4
4-F-C6H4
7
8a
8b
9
10
11a
11b
12a
12b
12c
12d
12e
12f
* Crystallization Solvent (s): A: Acetic acid, D: Dioxane, DMF: N,N-Dimethylformamide, E: Ethanol, M: Methanol, PE: Petroleum
ether (60:80), W: Water.
The found values (F) are within l 0.4% of the calculated (C) values.
a)
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
Substituted Thiazoles as Antimicrobial, Anticancer Agents
431
effectiveness against the non-small cell lung cancer Hop- design more potent and selective antimicrobial and / or
92 and melanoma SK-MEL-2 cell lines (GI% 80.2 and 96.8, anticancer agents.
respectively). Interestingly, compound 12f has satisfied
the pre-determined threshold inhibition criteria and The authors are deeply thankful to the Deanship of Scientific
consequently was carried over to be tested in the five- Research, King Abdulaziz University, Jeddah, Kingdom Saudi
dose assay.
Arabia, for the financial support of this research project (427/
004). Profound gratitude is conveyed to Dr. Yasser R. Abdel-Fat-
tah, Genetic Engineering and Biotechnology Research Institute
(GEBRI), Mubarak City for Scientific Research and Technology
Applications, Alexandria, Egypt, for his great effort in carry-
ing out the microbiological screening. Extendable thanks are
Conclusion
In conclusion, the results obtained in this study revealed due to the staff members of the Department of Health and
that 13 compounds out of the newly synthesized com- Human Services, National Cancer Institute (NCI), Bethesda,
pounds displayed a variable degree of antibacterial activ- Maryland, U.S.A. for carrying out the anticancer screening of
ity against Gram-positive bacteria, particularly S. aureus the newly synthesized compounds.
and B. subtilis. Meanwhile, they were totally inactive
against the three tested strains of Gram-negative bacte- The authors have declared no conflict of interest.
ria. Additionally, four compounds were able to exert anti-
fungal activity against C. albicans, whereas, all of the
tested compounds lacked antifungal activity against Asp.
niger fungus. Potential antibacterial and antifungal activ-
Experimental
ities were confined mainly to compounds comprising the
Chemistry
thiosemicarbazide function 6a–f at position-5, and those
substituted with both the thioureido and thiosemicarba-
zide moieties 12a–f at positions-2 and -5 of the thiazole
ring, respectively. Compounds 6f and 12f (R = 4-F-C6H4)
could be considered as the most active members in the
present investigation with a broad spectrum potential
antibacterial activity against the three types of Gram-pos-
itive bacteria tested comparable to that of ampicillin,
together with a good antifungal activity against C. albi-
cans comparable to that of clotrimazole. Special high
activity was displayed by compounds 6d, 6f, and 12f
against B. subtilis, which were twice as active as ampicil-
lin. The best antifungal activity was shown by compound
6d, which was 50% less active than that of clotrimazole.
On the other hand, according to the current one-dose
protocol of the NCI in-vitro disease-oriented human cells
screening panel assay, the non-small cell lung cancer
Hop-92, ovarian cancer IGROV1, and melanoma SK-MEL-2
cell lines exhibited interesting sensitivity against most of
the tested 17 compounds. Compound 12f proved to be
the most active anticancer member in this study with a
broad spectrum of activity against most of the tested sub-
panel tumor cell lines with particular effectiveness
against the non-small cell lung cancer Hop-92 and mela-
noma SK-MEL-2 cell lines. Interestingly, compound 12f
has satisfied the pre-determined threshold inhibition cri-
teria and consequently was carried over to be tested in
the five-dose assay. Finally, such type of substituted thia-
zoles could be used as a template for future development
through modification or derivatization in order to
Melting points were determined in open glass capillaries on a
Gallenkamp melting point apparatus (Weiss-Gallenkamp, Lon-
don, UK) and were uncorrected. The infrared (IR) spectra were
recorded on Perkin-Elmer 297 infrared spectrophotometer (Per-
kin-Elmer, USA) using the NaCl plate technique. The 1H-NMR
spectra were recorded on a Varian EM 360 spectrometer (Varian
Inc., Palo Alto, CA, USA) using tetramethylsilane as the internal
standard and DMSO-d6 as the solvent (Chemical shifts in (d,
ppm). Splitting patterns were designated as follows: s: singlet; d:
doublet; m: multiplet. Elemental analyses were performed at
the Microanalytical Unit, Faculty of Science, King Abdul-Aziz
University, Jeddah, Saudi Arabia, and the found values were
within l 0.4% of the theoretical values. Follow up of the reac-
tions and checking the homogeneity of the compounds were
made by TLC on silica gel-protected aluminum sheets (Type 60
F254, Merck, Germany) and the spots were detected by exposure
to UV-lamp at k = 254. The synthesis of ethyl 2-amino-4-methyl-
thiazole-5-carboxylate 1 was performed according to a reported
literature procedure [36].
Ethyl 2-acetylamino-4-methylthiazole-5-carboxylate 2
The thiazole 1 (0.93 g, 5 mmol) was warmed with acetic anhy-
dride (6 mL) for 1 h, then the mixture was allowed to attain
room temperature. The deposited solid was filtered, washed
with petroleum ether (60–808C) dried and recrystallized. Physi-
cochemical and analytical data are recorded in Table 3. IR (cm–
1): 3560–3100 (NH), 1730 (C=O), 1670 (C=O). H-NMR (d, ppm):
1
1.35 (t, J = 9 Hz, 3H, ester-CH3), 2.15 (s, 3H, acetyl-CH3), 2.62 (s, 3H,
Thiazol-C4-CH3), 4.26 (q, J = 9 Hz, 2H, ester-CH2), 8.08 (brs, 1H,
NH).
2-Acetamido-4-methylthiazole-5-carboxylic acid
hydrazide 3
A solution of 2 (2.28 g, 10 mmol) in ethanol (20 mL) was heated
under reflux with hydrazine hydrate (1.5 g, 30 mmol) for 4 h.
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

432
M. S. Al-Saadi et al.
Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
The reaction mixture was allowed to attain room temperature
and the deposited solid was filtered, washed, dried, and recrys-
tallized. Physicochemical and analytical data are recorded in
Table 3. IR (cm– 1): 3750–3270 (NH), 1685 (C=O), 1645 (C=O). 1H-
NMR (d, ppm): 2.31 (s, 3H, CH3-CO), 2.54 (s, 3H, Thiazol-C4-CH3),
7.68 (brs, 1H, NH), 8.10 (m, 1H, NH), 9.20 (brs, 2H, NH2).
2-Acetamido-N-formyl-4-methylthiazole-5-carboxylic acid
hydrazide 7
A solution of the acid hydrazide 3 (1.1 g, 5 mmol) in formic acid
(10 mL) was heated under reflux for 1 h, during which a solid
product was partially crystallized out. After being cooled to
room temperature, the product was filtered, washed, dried, and
recrystallized. Physicochemical and analytical data are recorded
in Table 3. IR (cm– 1): 3145–2930 (NH), 1667 (C=O aldehyde),
1630 (C=O amide). 1H-NMR (d, ppm): 2.26 (s, 3H, CO-CH3), 2.57 (s,
3H, Thiazol-C4-CH3), 5.90 (brs, 1H, NH), 8.25 (s, 1H, CHO), 9.04
(brs, 1H, NH), 10.12 (s, 1H, NH).
2-Acetamido-N-arylidine-4-methylthiazole-5-carboxylic
acid hydrazides 4a–g
A solution of 3 (1.1 g, 5 mmol) and the appropriate aldehyde
(5 mmol) in glacial acetic acid (15 mL) was refluxed for 6–8 h.
The solid separated upon cooling was filtered, washed with cold
ethanol, dried, and recrystallized. Physicochemical and analyti-
cal data are recorded in Table 3. IR (cm– 1): 3540–2775 (NH),
2-Acetamido-N-(4-substituted benzenesulfonyl)-4-
methylthiazole-5-carboxylic acid hydrazides 8a, b
A mixture of the start 3 (1.1 g, 5 mmol) and benzenesulfonyl
chloride or tosyl chloride (5 mmol) in pyridine (10 mL), was
heated under reflux for 3 h. The reaction mixture was left to
attain room temperature, poured on crushed ice and the sepa-
rated solid product was filtered, washed with water, dried, and
recrystallized. Physicochemical and analytical data are recorded
in Table 3. IR (cm– 1): 3275–2760 (NH), 1680–1690 (C=O). 1H-NMR
(d, ppm) for 8a (X = H): 2.24 (s, 3H, CO-CH3), 2.57 (s, 3H, Thiazol-C4-
CH3), 7.55–7.86 (m, 6H, 5 Ar-H + NH), 8.12 (brs, 1H, NH), 7.95 (s,
1H, NH). For 8b (X = CH3): 2.30 (s, 3H, CO-CH3), 2.47 (s, 3H, tolyl-
CH3), 2.55 (s, 3H, Thiazol-C4-CH3), 7.26–7.81 (m, 5H, 4 Ar-H + NH),
7.95 (brs, 1H, NH), 8.25 (s, 1H, NH).
1
1705–1645 (C=O). H-NMR (d, ppm) for 4b (R = 4-CH3-C6H4): 2.24
(s, 3H, CH3-CO), 2.39 (s, 3H, CH3), 2.49 (s, 3H, Thiazol-C4-CH3),
7.25–7.81 (m, 4H, Ar-H), 7.91 (brs, 1H, NH), 8.25 (s, 1H, NH), 8.70
(s, H, CH=N). For 4d (R = 2-thienyl): 2.21 (s, 3H, CH3-CO), 2.54 (s,
3H, Thiazol-C4-CH3), 7.17–7.34 (m, 3H, thiophen-3H), 8.03 (brs,
1H, NH), 8.32 (s, 1H, NH), 8.49 (s, H, CH=N). For 4h (R = 1-morpho-
linyl): 2.26 (s, 3H, CH3-CO), 2.64 (s, 3H, Thiazol-C4-CH3), 3.92 (m,
2H, morpholin-2H), 4.21 (m, 2H, morpholin-2H), 7.68 (brs, 1H,
NH), 8.20 (s, 1H, NH), 8.59 (s, H, CH=N).
4-Substituted-1-(2-acetamido-4-methylthiazole-5-
carbonyl)semicarbazides 5a, b
2-Amino-4-methylthiazole-5-carboxylic acid hydrazide 9
A solution of the 1 (0.93 g, 5 mmol) in ethanol (15 mL), was
treated with hydrazine hydrate (0.75 g, 15 mmol) and the reac-
tion mixture was heated under reflux for 3 h. The obtained pre-
cipitate upon cooling was filtered, washed, dried, and recrystal-
lized. Physicochemical and analytical data are recorded in
Table 3. IR (cm– 1): 3320-2760 (NH), 1670 (C=O). 1H-NMR (d, ppm):
2.45 (s, 3H, Thiazol-C4-CH3), 6.28 (brs, 2H, NH2), 8.20 (m, 1H, NH),
9.16 (brs, 2H, NH2).
To a solution of the acid hydrazide 3 (1.1 g, 5 mmol) in pyridine
(15 mL), was added cyclohexyl or phenyl isocyanate (6 mmol).
The reaction mixture was refluxed for 6–8 h, then allowed to
attain room temperature. The reaction mixture was poured on
crushed ice and the separated solid product was filtered, washed
with water, dried, and recrystallized. Physicochemical and ana-
lytical data are recorded in Table 3. IR (cm– 1): 3640-2910 (NH),
1720-1630 (C=O). 1H-NMR (d, ppm) for 5a (R = cyclohexyl): 1.41–
2.02 (m, 11H, cyclohexyl-H), 2.16 (s, 3H, CH3-CO), 2.52 (s, 3H, Thia-
zol-C4-CH3), 5.38 (brs, 1H, NH), 7.81 (brs, 1H, NH), 8.62–9.10 (m,
2H, 2 NH). For 5b (R = C6H5): 2.15 (s, 3H, CH3-CO), 2.52 (s, 3H, Thia-
zol-C4-CH3), 5.90 (brs, 1H, NH), 7.08–7.92 (m, 6H, 5 Ar-H + NH),
8.48–9.30 (m, 2H, 2 NH).
2-Acetamido-N-acetyl-4-methylthiazole-5-carboxylic acid
hydrazide 10
The acid hydrazide 9 (0.86 g, 5 mmol) was warmed with acetic
anhydride (10 mL) for 2 h, then the mixture was allowed to
attain room temperature. The deposited solid was filtered,
washed with petroleum ether (60–808C) and recrystallized.
Physicochemical and analytical data are recorded in Table 3. IR
(cm– 1): 3550–3105 (NH), 1758 (C=O acetyl), 1734 (C=O acetyl),
1667 (C=O amide). 1H-NMR (d, ppm): 2.37 (s, 3H, CH3), 2.49 (s, 3H,
CH3), 2.64 (s, 3H, Thiazol-C4-CH3), 5.85 (brs, 1H, NH), 8.51 (brs, 1H,
NH), 9.36 (brs, 1H, NH).
4-Substituted-1-(2-acetamido-4-methylthiazole-5-
carbonyl)thiosemicarbazides 6a–f
To a solution of the acid hydrazide 3 (1.1 g, 5 mmol) in pyridine
(15 mL), was added the appropriate isothiocyanate (6 mmol) and
the mixture was refluxed for 4–6 h. Working up of the reaction
mixture was carried out as described under 5a, b. Physicochemi-
cal and analytical data are recorded in Table 3. IR (cm– 1): 3470–
2935 (NH), 1640-1710 (C=O), 990–954 (NCS). 1H-NMR (d, ppm) for
6a (R = CH3): 2.29 (s, 3H, CH3-CO), 2.47 (s, 3H, CH3), 2.53 (s, 3H,
Thiazol-C4-CH3), 4.37–4.61 (m, 2H, 2 NH), 7.70 (brs, 1H, NH), 8.57
(brs, 1H, NH). For 6d (R = C6H5): 2.23 (s, 3H, CH3-CO), 2.57 (s, 3H,
Thiazol-C4-CH3), 6.20–6.43 (m, 2H, 2 NH), 7.65–7.90 (m, 5H, Ar-
H), 8.64 (brs, 1H, NH), 9.01 (brs, 1H, NH). For 6e (R = 4-CH3-C6H4):
2.31 (s, 3H, CH3-CO), 2.46 (s, 3H, tolyl-CH3), 2.55 (s, 3H, Thiazol-C4-
CH3), 4.39–4.65 (m, 2H, 2 NH), 7.05–7.53 (m, 4H, Ar-H), 7.72 (brs,
1H, NH), 8.55 (brs, 1H, NH).
4-Substituted-1-[2-(N-substituted ureido)-4-
methylthiazol-5-carbonyl]semicarbazides 11a, b
To a solution of the acid hydrazide 9 (0.86 g, 5 mmol) in pyridine
(15 mL), was added cyclohexyl or phenyl isocyanate (12 mmol),
and the mixture was refluxed for 6–8 h. Working up of the reac-
tion mixture was carried out as described under 5a, b. Physico-
chemical and analytical data are recorded in Table 3. IR (cm– 1):
3570-2890 (NH), 1716–1628 (C=O). 1H-NMR (d, ppm) for 11a (R =
cyclohexyl): 1.36–2.05 (m, 22H, cyclohexyl-H), 2.54 (s, 3H, Thia-
zol-C4-CH3), 6.07 (brs, 1H, NH), 6.20 (brs, 1H, NH), 7.98 (brs, 1H,
NH), 8.19 (brs, 1H, NH), 8.61 (brs, 1H, NH). For 11b (R = C6H5): 2.52
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
Substituted Thiazoles as Antimicrobial, Anticancer Agents
433
(s, 3H, Thiazol-C4-CH3), 6.03 (brs, 1H, NH), 6.14 (brs, 1H, NH),
6.89–7.57 (m, 10H, Ar-H), 8.01 (brs, 1H, NH), 8.14 (brs, 1H, NH),
8.52 (brs, 1H, NH).
Preliminary in-vitro anticancer screening
Out of the newly synthesized derivatives, 17 compounds,
namely 3, 4a, d–h, 5a, b, 6c, f, 7a, 8a, 10, 11a, b, 11d–h, and 12f;
were selected by the National Cancer Institute (NCI) in-vitro dis-
ease-oriented human cells screening panel assay to be evaluated
for their in-vitro anticancer activity. Primary in-vitro one-dose
anticancer assay was performed using the full NCI 60 cell panel
in accordance with the current protocol of the Drug Evaluation
Branch, NCI, Bethesda [38–40]. These cell lines were incubated
with one concentration (10 lM) for each tested compound. A
48 h continuous drug exposure protocol was used, and a sulpho-
rhodamine B (SRB) protein assay was employed to estimate cell
viability or growth.
4-Substituted-1-[2-(N-substituted thioureido)-4-
methylthiazol-5-carbonyl]thiosemicarbazides 12a–f
To a solution of the acid hydrazide 9 (0.86 g, 5 mmol) in pyridine
(15 mL), was added the appropriate isothiocyanate (12 mmol).
The reaction mixture was refluxed for 8–10 h then cooled to
room temperature. Working up of the reaction mixture was car-
ried out as described under 6a–b. Physicochemical and analyti-
cal data are recorded in Table 3. IR (cm– 1): 3520–2920 (NH),
1700- 1635 (C=O), 985–950 (NCS). 1H-NMR (d, ppm) for 12a (R =
CH3): 2.45 (s, 3H, Thiazol-C4-CH3), 2.51 (s, 3H, CH3), 2.59 (s, 3H,
CH3), 6.03 (m, 2H, NH), 8.23 (brs, 2H, NH), 8.64 (brs, 1H, NH). For
12c (R = CH2-C6H5): 2.51 (s, 3H, Thiazol-C4-CH3), 4.77 (d, 2H, CH2),
4.85 (d, 2H, CH2), 6.11 m, 2H, NH), 7.09–7.66 (m, 10H, Ar-H), 8.15
(brs, 2H, NH), 8.55 (brs, 1H, NH). For 12f (R = 4-F-C6H4): 2.49 (s, 3H,
Thiazol-C4-CH3), 6.11 (m, 2H, NH), 6.87–7.71 (m, 8H, Ar-H), 8.20
(brs, 2H, NH), 8.61 (brs, 1H, NH).
References
[1] E. Akbas, I. Berber, Eur. J. Med. Chem. 2005, 40, 401–405
(references are cited therein).
[2] G. Turan-Zitouni, Z. A. Kaplancikli, M. T. Yildiz, P. Cheval-
let, D. Kaya, Eur. J. Med. Chem. 2005, 40, 607–613 (referen-
ces are cited therein).
Antimicrobial screening
[3] S. Eckhardt, Curr. Med. Chem. Anticancer Agents 2002, 2,
419–439.
Inhibition zone (IZ) measurement
[4] M. Tuncbilek, N. Altanlar, Arch. Pharm. Chem. Life Sci. 2006,
339, 213–216.
Standard sterilized filter paper discs (5 mm diameter) impreg-
nated with a solution of the test compound in DMSO (1 mg/mL)
were placed on an agar plate seeded with the appropriate test
organism in triplicates. The utilized test organisms were: Staph-
ylococcus aureus (ATCC 6538), Bacillus subtilis (NRRL B-14819), and
Bacillus cereus (ATCC 14579) as examples of Gram-positive bacte-
ria and Escherichia coli (ATCC 25922), Pseudomonas aeruginosa
(ATCC 27853), and Klebsiella pneumonia (clinical isolate) as exam-
ples of Gram-negative bacteria. Candida albicans (ATCC 10231)
and Aspergillus niger (recultured) fungal strains were utilized as
representatives for fungi. Ampicillin trihydrate and clotrima-
zole were used as standard antibacterial and antifungal agents,
respectively. DMSO alone was used as control at the same above-
mentioned concentration. The plates were incubated at 378C for
24 h for bacteria and for seven days for fungi. The results were
recorded for each tested compound as the average diameter of
inhibition zones of bacterial growth around the discs in mm
(Table 1).
[5] O. Bozdag-Dundar, O. Ozgen, A. Mentese, N. Altanlar, et al.,
Bioorg. Med. Chem. 2007, 15, 6012–6017.
[6] S. Bondock, W. Khalifa, A. A. Fadda, Eur. J. Med. Chem. 2007,
42, 948–954.
[7] T. M. de Aquino, A. P. Liesen, R. E. A. da Silva, V. T. Lima, et
al., Bioorg. Med. Chem. 2008, 16, 446–456.
[8] H. T. Y. Fahmy, Boll. Chim. Farm. 2001, 140, 422–427.
[9] C.-L. Liu, Z.-M. Li, B. Zhong, J. Flour. Chem., 2004, 125, 1287–
1290.
[10] R. P. Tenorio, C. S. Carvalho, C. S. Pessanha, J. G. De Lima,
et al., Bioorg. Med. Chem. Lett. 2005, 15, 2575–2578.
[11] V. A. Ryabinin, A. N. Sinyakov, V. R. de Soultrait, A. Cau-
mont, et al., Eur. J. Med. Chem. 2000, 35, 989–1000.
[12] W.-L. Wang, D.-Y. Yao, M. Gu, M.-Z. Fan, et al., Bioorg. Med.
Chem. Lett. 2005, 15, 5284–5287.
[13] H. I. El-Subbagh, W. A. El-Naggar, F. A. Badria, Med. Chem.
Res. 1994, 3, 503–516.
Minimal inhibitory concentration (MIC) measurement
MICs were measured for compounds that showed significant
growth inhibition zones (F14 mm) using the two-fold serial
dilution technique [37]. The microdilution susceptibility test in
Mꢀller–Hinton Broth (Oxoid) and Sabouraud Liquid Medium
(Oxoid) was used for the determination of antibacterial and anti-
fungal activity, respectively. Stock solutions of the tested com-
pounds, ampicillin trihydrate and clotrimazole were prepared
in DMSO at concentration of 800 lg/mL followed by two-fold
dilution at concentrations of (400, 200, …, 6.25 lg/mL). The
microorganism suspensions at 106 CFU/ml (Colony Forming
Unit/mL) concentration were inoculated to the corresponding
wells. Plates were incubated at 368C for 24 h to 48 h and the min-
imal inhibitory concentrations (MIC) were determined. Control
experiments were also done. The results were recorded for each
tested compound in Table 2.
[14] H. I. El-Subbagh, A. M. Al-Obaid, Eur. J. Med. Chem. 1996, 31,
1017–1021.
[15] B. Jiang, X.-H. Gu, Bioorg. Med. Chem. 2000, 8, 363–371.
[16] J. A. Yalowitz, K. Pankiewicz, S. E. Patterson, H. N. Jayaram,
Cancer Lett. 2002, 181, 31–38.
[17] L. Garuti, M. Roberti, A. Pession, E. Leoncini, S. Hrelia, Bio-
org. Med. Chem. Lett. 2001, 11, 3147–3149.
[18] C. A. Bolos, K. T. Papazisi, A. H. Kortsaris, S. Voyatzi, et al., J.
Inorg. Biochem. 2002, 88, 25–36.
[19] Z. Li, Q. Yang, X. Qian, Bioorg. Med. Chem. 2005, 13, 4864–
4870.
[20] R. Cejudo, G. Alzuet, M. Gonzalez-Alvarez, J. L. Garcia-
Gimenez, et al., J. Inorg. Biochem. 2006, 100, 70–79.
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com

434
M. S. Al-Saadi et al.
Arch. Pharm. Chem. Life Sci. 2008, 341, 424–434
[21] A. S. Kiselyov, E. Piatnitski, M. Semenova, V. V. Semenov,
[31] I. A. Shehata, H. I. El-Subbagh, A. M. Abdelal, M. A. El–Sher-
Bioorg. Med. Chem. Lett. 2006, 16, 602–606.
beny, Med. Chem. Res. 1996, 6, 148–163.
[22] M. F. Earle, R. I. Glazer, Cancer Res. 1983, 43, 133–137.
[32] G. L. Almajan, A. Innocenti, L. Puccetti, G. Manole, et al.,
Bioorg. Med. Chem. Lett. 2005, 15, 2347–2352.
[23] G. J. Tricot, H. N. Jayaram, G. Weber, R. I. Hoffman, Int. J.
Cell Cloning 1990, 8, 161–170.
[33] P. Vicini, A. Geronikaki, M. Incerti, B. Busonera, et al., Bio-
org. Med. Chem. 2003, 11, 4785–4789.
[24] P. Callery, P. Gannett in Principles of Medicinal chemistry,
(Eds.: W. O. Foye, T. L. Lemke, D. A. Williams), 5th Ed, Lip-
pincott Williams and Wilkins, USA, 2002, pp. 938–941.
[34] U. El-Ayaan, A. A.-M. Abdel-Aziz, Eur. J. Med. Chem. 2005, 40,
1214–1221.
[25] A. A. Bekhit, H. T. Y. Fahmy, Sh. A. F. Rostom, A. M. Baraka,
[35] L. Shi, H.-M. Ge, S.-H. Tan, H.-Q. Li, et al., Eur. J. Med. Chem.
2007, 42, 558–564.
Eur. J. Med. Chem. 2003, 38, 27–36.
[26] H. T. Y. Fahmy, Sh. A. F. Rostom, A. A. Bekhit, Arch. Pharm.
Med. Chem. 2002, 335, 213–222.
[36] J. Kempson, W. J. Pitts, J. Barbosa, J. Guo, et al., Bioorg. Med.
Chem. Lett. 2005, 15, 1829–1833.
[27] H. T. Y. Fahmy, Sh. A. F. Rostom, M. N. S. Saudi, J. K. D.
Zjawiony, J. Robins, Arch. Pharm. Med. Chem. 2003, 336,
216–225.
[37] J. E. Conte and S. L. Barriere, Manual of Antibiotics and
Infectious Disease, 1st Ed., Lea and Febiger, USA, 1988, p.
135.
[28] Sh. A. F. Rostom, Bioorg. Med. Chem. 2006, 14, 6475–6485.
[38] M. R. Grever, S. A. Schepartz, B. A. Chabner, Semin. Oncol.
1992, 19, 622–638.
[29] H. M. Faidallah, M. S. Al-Saadi, Sh. A. F. Rostom, H. T. Y.
Fahmy, Med. Chem. Res. 2008, in Press.
[39] M. R. Boyd, K. D. Paull, Drug Dev. Res. 1995, 34, 91–109.
[30] M. S. Al-Saadi, Sh. A. F. Rostom, H. M. Faidallah, Arch.
Pharm. Chem. Life Sci. 2008, 341, 181–190.
[40] A. Monks, D. Scudiero, P. Skehan R., Shoemaker, K. Paull,
et al., J. Natl. Cancer Inst. 1991, 83, 757–766.
i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com