Antimicrobial and antiurease activities of newly synthesized morpholine derivatives containing an azole nucleus

Article abstract of DOI:10.1007/s00044-012-0318-1

2-[6-(Morpholin-4-yl)pyridin-3-ylamino]acetohydrazide (4) was obtained starting from 6-morpholin-4-ylpyridin-3-amine (2) via the formation of ester (3) and then converted to the corresponding Schiff bases (5, 6) with the reaction with aromatic aldehydes.

Full text of DOI:10.1007/s00044-012-0318-1

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2013) 22:3629–3639
DOI 10.1007/s00044-012-0318-1
ORIGINAL RESEARCH
Antimicrobial and antiurease activities of newly synthesized
morpholine derivatives containing an azole nucleus
•
Hakan Bektas¸ S¸ule Ceylan Neslihan Demirbas¸
•
•
•
˘
¨
S¸engu¨l Alpay-Karaoglu Bahar Bilgin Sokmen
Received: 24 June 2012 / Accepted: 25 October 2012 / Published online: 29 November 2012
Ó The Author(s) 2012. This article is published with open access at Springerlink.com
Abstract 2-[6-(Morpholin-4-yl)pyridin-3-ylamino]acet-
ohydrazide (4) was obtained starting from 6-morpholin-4-
ylpyridin-3-amine (2) via the formation of ester (3) and then
converted to the corresponding Schiff bases (5, 6) with the
reaction with aromatic aldehydes. The carbothioamide (9),
obtained from the reaction of hydrazide with phenylisothi-
ocyanate, was converted to the corresponding 1,2,4-triazole
(11) and 1,3,4-thiadiazole (12) derivatives by the treatment
with NaOH or H2SO4, respectively. The cyclocondenzation
of 9 with 4-chlorophenacyl bromide or ethyl bromoacetate
produced the corresponding 1,3-thiazole (10) or 1,3-thia-
zolidine derivatives (13), respectively. Antimicrobial and
antiurease activities of newly synthesized compounds were
investigated. Some of them were found to be active on
M. smegmatis, and they displayed activity toward C. albi-
cans and S. cerevisiae in high concentration. Compound 10
proved to be the most potent showing an enzyme inhibition
activity with an IC50 = 2.37 0.19 lM.
Keywords Morpholine ꢀ 1,2,4-Triazole ꢀ
1,3,4-Oxadiazole ꢀ Mannich base ꢀ
Antimicrobial activity ꢀ Antiurease activity
Introduction
Urea amidohydrolases (ureases) have been known as a
class of large heteropolymeric enzymes with the active site
containing two nickel (II) atoms and to accelerate hydro-
lysis of urea to ammonia gas with the reaction rate at least
1014 over the spontaneous reaction. Ureases are widely
distributed in nature and are found in a variety of plants,
algae, fungi, and bacteria (Kot et al., 2010). Medically,
bacterial ureases have been reported as important virulence
factors implicated in the pathogenesis of many clinical
conditions such as pyelonephritis, hepatic coma, peptic
ulceration, and the formation of injection-induced urinary
stones and stomach cancer. The catalytic mechanism of
their action has been believed to be the same of all urease
inhibitors in which the amino acid sequences of the active
site are principally conserved (Xiao et al., 2010). The
active site of the native enzyme binds three water mole-
cules and a hydroxide ion bridged between two nickel ions
(Bachmeier et al., 2002). In the course of enzymatic
reaction, urea replaces these three water molecules and
bridges the two metal ions. The surrounding by a hydro-
gen-bonding network strongly activates the inert urea
molecule; it is subsequently attacked by the hydroxide ion,
forming a tetrahedral transition state. As a result, ammonia
is released from the active site followed by the negatively
charged carbamate (Adil et al., 2011). The latter decom-
poses rapidly and spontaneously, yielding a second mole-
cule of ammonia. The ammonia generated may cause
¨
H. Bektas¸ (&) ꢀ B. B. Sokmen
Department of Chemistry, Faculty of Arts and Sciences,
Giresun University, 28049 Giresun, Turkey
e-mail: hakanbe_28@hotmail.com
S¸. Ceylan
Department of Forest Industry Engineering, Faculty of Forest,
Artvin Coruh University, 08100 Artvin, Turkey
N. Demirbas¸
Department of Chemistry, Faculty of Sciences, Karadeniz
Technical University, 61080 Trabzon, Turkey
˘
S¸. Alpay-Karaoglu
Department of Biology, Faculty of Arts and Sciences,
Rize University, 53100 Rize, Turkey
123

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Med Chem Res (2013) 22:3629–3639
disruption to several metabolic functions in a large number
of animal tissues and organs (Adil et al., 2011).
During the recent decades, the human population being
afflicted with life-threatening infectious diseases caused
by multidrug-resistant Gram-positive and Gram-negative
pathogen bacteria has been increasing at an alarming lscale
around the world as a result of antimicrobial resistance. In
spite of the wide range of antimicrobial drugs with different
mechanisms of action used for the treatment of microbial
infections either alone or in combination and also the exis-
tence of many compounds used in different phases of clinical
trials, microbial infections have been posing a worldwide
problem. There is already evidence that antimicrobial
resistance is associated with an increase in mortality (Bayrak
et al., 2010a, b, 2009a, b; Demirbas et al., 2009). The
growing number of reports of antibiotic resistance world-
wide has led to fears that some lethal human pathogens, such
as Mycobacterium tuberculosis, will soon become untreat-
able (Dye and Williams, 2009; Dye and Phill, 2006; Koca
et al., 2005; Zalavadiya et al., 2009). Tuberculosis (TB)
causes the death of approximately three million patients in
the world every year. These numbers make TB one of the
leading infectious causes of death, eclipsed only by AIDS.
Synthetic drugs for treating TB have been available for over
half a century, but incidences of the disease continue to be on
the rise worldwide. The causative organism, Mycobacterium
tuberculosis, is a tremendously successful colonizer of the
human host and is estimated to have latently infected
approximately one-third of humanity. A growing number of
immunocompromised patients are attributed to cancer che-
motherapy, organ transplantation, and HIV infection, which
are the major factors contributing to this increase. Therefore,
it is necessary to search for and synthesize new classes of
antimicrobial compounds that are effective against patho-
genic microorganisms that have developed resistance to the
antibiotics (Dye and Williams, 2009; Dye and Phill, 2006;
Koca et al., 2005; Zalavadiya et al., 2009; Bayrak et al.,
2010a, b).
Urease is also indispensable for colonization of human
gastric mucosa by Helicobacter pylori. The ammonia pro-
duced has been shown to be toxic for various gastric cell
lines. Furthermore, urease activity was proposed to damage
the gastric epithelium via its interaction with the immune
system by stimulating an oxidative burst in human neutro-
phils (Ito et al., 1998). H2O2 generated in this oxidative burst
probably reacts with ammonia and chloride to yield the toxic
monochloramine (Kot et al., 2010). Finally, the ammonia
may reach the serum and contribute to symptoms of hepatic
encephalopathy in patients suffering from cirrhosis. Apart
from ammonia, the carbon dioxide generated by urea
hydrolysis may play a significant role for survival of
H. pyloriin thegastric mucosa(Cobena et al., 2008;Miroslawa
et al., 2010; Xiao et al., 2010; Khan et al., 2010a, b; Ito et al.,
1998; Keri et al., 2002; Ashiralieva and Kleiner, 2003).
Moreover, urea constitutes the predominant source of
nitrogen containing fertilizers used in agriculture,
accounting for 50 % of the total world fertilizer nitrogen
consumption. However, the efficiency of urea is decreased
by its hydrolysis with the enzyme urease to ammonia gas in
soil. Besides the economic impact for farmers, NH3 lost to
the atmosphere from applied urea causes eutrophication
and acidification of natural ecosystems on a regional scale
(Cobena et al., 2008).
Several classes of compounds have been reported as the
agents having antiurease activity; among them hydroxam-
icacids are the best recognized urease inhibitors (Adil
et al., 2011; Krajewska, 2009; Muri et al., 2003). Phos-
phoramidates, another class of antiurease agents, have been
reported as the most potent compounds (Amtul et al.,
2002; Kot et al., 2001). However, the teratogenicity of
hydroxamicacid in rats and degradation of phosphorami-
´
dates at low pH (Adil et al., 2011, Domınguez et al., 2008;
Kreybig et al., 1968) restrict their use as a drug in vivo.
Another class of compounds showing enzyme’s inhibitory
activity is polyphenols such as gallocatechin that is a pol-
yphenol extracted from green tea and quercetin, a naturally
occurring flavonoid having anti-H. pylori activity
(Matsubara et al., 2003; Shin et al., 2005).
In the field of medicinal chemistry, azoles belong to a
class of antimicrobial agents that are widely used and
studied because of their safety profile and high therapeutic
index. Ribavirin, rizatriptan, alprazolam, vorozole, letroz-
ole, and anastrozole are the best examples of drugs con-
taining 1,2,4-triazole moiety (Ashok et al., 2007; Rao
et al., 2006; Hancu et al., 2007; Cai et al., 2007). Among
azole-based drugs, conazoles, such as itraconazole, fluco-
nazole, voriconazole, and ravuconazole constitute a major
class being used for the treatment of fungal infections (Yu
et al., 2007; Gupta et al., 2007; Schiller and Fung, 2007).
Another important pharmacophore group is the mor-
pholine nucleus incorporated in a wide variety of thera-
peutically important drugs, one of which is linezolid which
belongs to the oxazolidinone class of antibiotics and is used
for the treatment of infections caused by gram-positive
bacteria (Wyrzykiewicz et al., 2006; Dixit et al., 2005;
In addition, some 1,2,4-triazoles, 1,3,4-oxadiazoles, and
1,3,4-thiadiazoles have also been reported as the com-
pounds possessing antiurease activity (Amtul et al., 2004;
Aktay et al., 2009; Bekircan et al., 2008). Recently, some
complexes of Schiff bases with metal ions showed signif-
icant inhibitory activities against urease (Shi et al., 2007;
You et al.,2010) along with other metal complexes (Cheng
et al.,2009). However, owing to the presence of heavy
metal atoms, these types of compounds can inflict toxic
effects on human body (Duruibe et al., 2007); hence, such
molecules cannot be used as drugs.
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Med Chem Res (2013) 22:3629–3639
3631
Raparti et al., 2009; Bektas et al., 2010, 2012; Bayrak
et al., 2009a, b). In addition, 4-phenylmorpholine deriva-
tives have been reported to possess antimicrobial, anti-
inflammatory, and central nervous system activities (Dixit
et al., 2006), Oxazolidinones are a relatively new class of
synthetic antibacterial agents, having a new mechanism of
action that involves early inhibition of bacterial protein
synthesis. This class of compounds is particularly active
against gram-positive organisms. Oxazolidinones are thought
not to be cross-resistant with other types of antibiotics
because of their different action mechanisms, which
include interaction with the bacterial ribosome to inhibit
bacteria. (Zheng et al., 2010; Giera et al., 2006; Das et al.,
2005; Gage et al., 2000; Cui et al., 2005). Hence, oxazo-
lidinone class of antibacterial compounds attracted con-
siderable attention of a number of research groups during
the last decade to get more efficacious and less toxic drug
(Srivastava et al., 2008).
The identification and synthesis of combinational che-
motherapeutic drugs with different mechanisms of action
and with few side effects are an important part of the
efforts to overcome antimicrobial resistance (Bayrak et al.,
2010a, b). A recent survey of novel small-molecule ther-
apeutics has revealed that the majority of the drugs results
from an analog-based approach and that their market share
represents two-thirds of all drug sales (Vicini et al., 2008).
In the present study, as a part of our ongoing study on
the synthesis of bioactive hybrid molecules, we aimed to
obtain the far derivatives of linezolid. It was reported that
SAR studies of linezolid demonstrated a high tolerance for
structural variation at the 4-position of the phenyl ring
(Weidner-Wells et al., 2002). In the structures of the newly
synthesized compounds, the phenyl ring substituted by
pyridine and oxazolidinone scaffold by other azole rings
such as 1,3-thiazole, 1,3-thiazolidinone, 1,2,4-triazole,
1,3,4-thiadiazole, and 1,3,4-oxadiazole nucleus.
Thiazolidinone derivatives have been further reported
to possess diverse pharmacological properties, such as
antibacterial, antifungal, anticonvulsant, anticancer, anti-
tuberculosis, and antihuman immunodeficiency virus type
1 (HIV-1) activities. Thiazolidinones are novel inhibitors
of the bacterial enzyme MurB, a precursor acting during
the biosynthesis of peptidoglycan as an essential compo-
nent of the cell wall of both gram-positive and gram-
negative bacteria. (Bonde and Gaikwad, 2004; Aridoss
et al., 2007; Ku¨c¸u¨kgu¨zel et al., 2002; Capan et al., 1999;
Barreca et al., 2001; Andres et al., 2000; El-Gaby et al.,
2009)
Results and discussion
The synthetic route for the newly synthesized compounds
(3–13) is illustrated and outlined in Schemes 1 and 2.
The synthesis of compound 3 was performed from the
reaction of ethyl bromoacetate with compound 2 that is
available commercially. Then, compound 3 was converted
to the corresponding hydrazide (4) by the treatment with
hydrazine hydrate. The FT-IR and 1H NMR spectra of
compound 4 displayed signals pointing the presence of
Scheme 1 Synthetic pathway
for the preparation of
compounds 1–6. i morpholine,
ii Pd/C catalyst, H2NNH2,
iii BrCH2CO2Et, iv H2NNH2,
v BrC6H4CHO, vi
N
N
N
ii
i
Cl
NO2
O
N
NO2
O
N
NH2
1
2
iii
C6H5CH=CHCHO
O
N
O
N
O
N
NHCH2
C
iv
O
N
NHCH2
C
OEt
NHNH2
3
4
vi
v
O
N
O
N
O
N
NHCH2
C
O
N
NHCH2
C
NHN
NHN
6
5
Br
123

3632
Med Chem Res (2013) 22:3629–3639
N
N
N
N
N
N
N
N
S
O
SH
O
N
NH
O
O
N
NH
ii
8
7
i
O
N
O
N
C
O
N
NHCH2
O
N
NHCH2
C
N
NHNH2
NHN
10
4
S
iii
Cl
iv
O
N
N
N
O
N
NHCH2
C
S
N
NHNH
SH
v
N
O
N
NH
NH
9
11
vi
vii
N
S
N
N
NH
O
N
NH
12
O
N
O
O
N
NHCH2
C
N
NHN
13
S
Scheme 2 Synthetic pathway for the preparation of compounds 7–13. i CS2/KOH, ii phenyl piperazine, iii PhNCS, iv BrCH2COC6H4(4-),
v NaOH, vi H2SO4, vii BrCH2CO2Et
hydrazide function, whereas the signals due to ester group
disappeared in the NMR spectrum. The treatment of hydra-
zide, 4 with aromatic aldehydes, namely, 4-bromobenzaldehyde
and cinnamaldehyde produced the corresponding Schiff
bases, compounds 5 and 6. In the 1H NMR spectra of these
compounds, the signal derived from NH2 group disap-
peared; instead, new signals originated from aldehyde
moiety were recorded at the related chemical shift values in
the 1H NMR and 13C NMR spectra. Moreover, these
compounds (5 and 6) exhibited EI-MS and elemental
analysis data consistent with the proposed structures.
The synthesis of 5-{[(6-morpholin-4-ylpyridin-3-yl)a-
mino]methyl}-1,3,4-oxadiazole-2-thiol (7) was carried out
from the reaction of hydrazide 4 with carbon disulfide in
the presence of potassium hydroxide. An evidence for the
formation of 7 is the absence of the signals corresponding to
hydrazide function in the FT-IR and 1H NMR spectra. The
D2O exchangeable signal observed at 13.45 ppm was
attributed to the SH proton located at the position-2 of 1,3,4-
oxadiazole ring. The reaction of 7 with phenylpiperazine in
the presence of formaldehyde afforded the corresponding
Mannich base, 5-{[(6-morpholin-4-ylpyridin-3-yl) amino]-
methyl}-3-[(4-phenylpiperazin-1-yl)methyl]-1,3,4-oxadiaz-
ole-2(3H)-thione (8). In NMR spectra of 7, the presence of
the peaks belonging to 4-phenylpiperazine nucleus con-
firmed the Mannich reaction.
The synthesis of N0-[(5-(4-chlorophenyl)-3-phenyl-1,
3-thiazol-2(3H)-ylidene]-2-{(6-morpholin-4-ylpyridin-
3-yl)amino}acetohydrazide (10) obtained from the cyclo-
condenzation reaction between 4-chlorophenacyl bromide
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Med Chem Res (2013) 22:3629–3639
3633
and compound 9 that was obtained by the treatment of
hydrazide 4 with phenylisothiocyanate. On the other hand,
the treatment of the same intermediate 9 with ethyl
bromoacetate resulted in the formation of 2-[(6-morpholin-
4-ylpyridin-3-yl)amino]-N0-(4-oxo-3-phenyl-1,3-thiazolidin-
2-ylidene)acetohydrazide 13. The structures of these
compounds were confirmed on the basis of FT-IR, EI-MS,
1H NMR, 13C NMR spectroscopic methods, and elemental
analysis.
presented in the Table 1. Among the compounds tested,
compound 8, which contains different heterocyclic moie-
ties such as morpholine, pyridine, piperazine, and 1,3,4-
oxadiazole important antimicrobial activity, was found to
be active against all the microorganisms. All compounds
except compounds 6, 7, 10, and 13 exhibited activity
toward Mycobacterium smegmatis (Ms), a nonpigmented,
rapidly growing mycobacterium and an atypical tubercu-
losis factor leading to morbidity and mortality. The highest
Ms activity with the MICvalue 15.6 lg/mL was observed
for compound 12 that is a 1,2,4-triazole derivative con-
taining morpholine and pyridine nuclei as well. All the
tested compounds were found to be active on yeast like
fungi, Candida albicans (Ca) and Saccharomyces cerevi-
siae (Sc), in high concentrations with the MIC values of
500 or 1,000 lg/mL, whereas all compounds, except
compound 8, displayed no activity against gram-negative
bacterial strain. In contrast to other compounds, compound
12 demonstrated a low activity against Pseudomonas
aeruginosa (Pa), a gram-negative bacillus.
The basic treatment of intermediate 9 afforded 5-[(6-
morpholin-4-ylpyridin-3-yl)methyl]-4-phenyl-4H-1,2,4-
triazole-3-thiol (11), while the cyclization of 9 in acidic
media yielded 5-[(6-morpholin-4-ylpyridin-3-yl)methyl]-
N-phenyl-1,3,4-thiadiazol-2-amine (12). In the 1H NMR
spectrum of compound 11, the signal due to SH group was
recorded at 13.91 ppm as an evidence of intramolecular
cyclization. This group was seen at 2,857 cm-1 in the
FT-IR spectrum of compound 11. Two NH signals were
recorded at 6.04 and 10.23 ppm as D2O exchangeable
peaks in the 1H NMR spectrum of compound 12. In the 13
C
NMR spectra of compounds 11 and 12, other signals
belonging to 1,2,4-triazole or 1,3,4-thiadiazole nuclei res-
onated at the chemical shift values consistent with the lit-
erature (Bektas et al., 2010, 2012). Furthermore, [M]? ion
peaks were observed at the related m/z values supporting
the proposed structures. In addition, these compounds gave
reasonable elemental analysis data.
Almost all the compounds showed moderate-to-good
urease inhibitory activity (Table 2). The inhibition was
increased with increasing compound concentration. Potent
compound have their activities in the range of 2.37–
13.23 lM. Lower IC50 values indicate higher enzyme
inhibitor activity. Compound 10 proved to be the most
potent showing an enzyme inhibition activity with an
IC50 = 2.37 0.19 lM. The least active compound 3 had
an IC50 = 13.23 2.25 lM.
The newly synthesized compounds 3–13 were evaluated
in vitro for their antimicrobial activities. The results are
Table 1 Antimicrobial activity of the compounds (lg/mL)
Comp. no
Microorganisms and minimal inhibition concentration
Ec
Yp
Pa
Ef
Sa
Bc
Ms
Ca
Sc
3
–
–
–
–
–
–
–
125
125
31.3
–
1,000
500
1,000
1,000
1,000
1,000
1,000
1,000
1,000
1,000
1,000
1,000
1,000
4
–
–
–
–
–
5
–
–
–
–
–
–
1,000
500
6
–
–
–
–
–
–
7
–
–
–
–
–
–
–
500
8
62.5
–
62.5
–
62.5
31.3
–
31.3
–
62.5
–
125
125
–
1,000
1,000
500
9
–
10
11
12
13
Amp.
Str.
Flu.
–
–
–
–
–
–
–
–
–
–
–
–
125
15.6
–
500
–
–
500
–
–
–
–
500
–
–
–
–
–
500
8
32
[128
2
2
\1
4
\8
\8
Ec: Escherichia coli ATCC 25922, Yp: Yersinia pseudotuberculosis ATCC 911, Pa: Pseudomonas aeruginosa ATCC 43288, Ef: Enterococcus
faecalis ATCC 29212, Sa: Staphylococcus aureus ATCC 25923, Bc: Bacillus cereus 702 Roma, Ms: Mycobacterium smegmatis ATCC 607,
Ca: Candida albicans ATCC 60193, Sc: S. cerevisiae RSKK 251, Amp.: Ampicillin, Str.: Streptomisin, Flu.: Fluconazole
123

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Med Chem Res (2013) 22:3629–3639
Costech Elemental Combustion System CHNS-O elemental
analyzer. All the compounds gave C, H, and N analysis
results within 0.4 % of the theoretical values. The mass
spectra were obtained on a Quattro LC–MS (70 eV) Instru-
ment. Compounds 1 and 2 are available commercially.
Table 2 The urease inhibitory activity of different concentrations of
morpholin derivatives
Compounds
IC50 (lM)a
3
13.23 2.25
7.92 1.43
6.87 0.06
8.29 2.30
7.01 0.68
4.99 0.59
8.07 1.25
2.37 0.19
4.77 0.92
6.05 1.19
4.46 0.22
4
5
Synthesis of compound 3
6
7
Ethylbromoacetate (10 mmol) was added to the mixture of
compound 2 (10 mmol), and triethylamine (10 mmol) was
added dropwise in dry tetrahydrofurane at 0–5 °C. Then,
the reaction content was allowed to reach to room tem-
perature and stirred for 11 h (the progress of the reaction
was monitored by TLC). The precipitated triethylammo-
nium salt was removed by filtration. After evaporating the
solvent under reduced pressure, a brown solid appeared.
This crude product was recrystallized from ethanol–water
(1:2) to afford the desired product.
8
9
10
11
12
13
a
Mean SD
Conclusion
Ethyl N-(6-morpholin-4-ylpyridin-3-yl)glycinate (2)
In this study, the synthesis of some morpholine derivatives
(3–13) were performed, some of which contain an azole
moiety, and their structures were confirmed by IR, 1H
NMR, 13C NMR, Mass spectroscopic, and elemental analy-
sis techniques. In addition, the newly synthesized com-
pounds were screened for their antimicrobial and
antiurease activities. Some of them were found to possess
activity on M. smegmatis, C. albicans ATCC, and
S. cerevisiae. Furthermore, all the compounds exhibited
moderate-to-good antiurease activity
Yield (1.27 g, 50 %); m.p. 83–84 °C; IR (KBr, m, cm-1):
3,378 (NH), 1,725 (C=O), 1,575 (C=N), 1,118 (C–O); H
1
NMR (DMSO-d6, d ppm): 1.17 (t, 3H, CH3, J = 7.4 Hz),
3.18 (t, 4H, 2NCH2, J = 4.8 Hz), 3.69 (t, 4H, 2OCH2,
J = 4.4 Hz), 3.84 (d, 2H, NHCH2, J = 6.4 Hz), 4.08 (q,
2H, OCH2CH3, J = 7 Hz), 5.57 (t, 1H, NH, J = 6.8 Hz),
6.67 (d, 1H, arH, J = 9 Hz), 6.92–6.98 (m, 1H, arH), 7.56
(d, 1H, arH, J = 2.4 Hz); 13C NMR (DMSO-d6, d ppm):
14.83 (CH3), 45.84 (NHCH2), 47.40 (2NCH2), 60.94
(CH2OCH3), 66.74 (2OCH2), arC: [108.94 (CH), 123.74
(CH), 132.35 (CH), 138.22 (C), 153.34 (C)], 172.08
(C=O); LC–MS: m/z (%) 266.257 [M?1]? (85), 164.12
(94); Anal.calcd (%) for C13H19N3O3 : C, 58.85; H, 7.22;
N, 15.84. Found: C, 58.65; H, 7.28; N, 15.85.
Experimental
Chemistry
General information for chemicals
Synthesis of compound 4
All the chemicals were purchased from Fluka Chemie AG
Buchs (Switzerland) and used without further purification.
Melting points of the synthesized compounds were deter-
mined in open capillaries on a Bu¨chi B-540 melting point
apparatus and are uncorrected. Reactions were monitored by
thin-layer chromatography (TLC) on silica gel 60 F254 alu-
minum sheets. The mobile phase was ethanol:ethyl acetate,
1:1, and detection was made using UV light. FT-IR spectra
were recorded as potassium bromide pellets using a Perkine
Hydrazide hydrate (25 mmol) was added to the solution of
compound 2 (10 mmol) in absolute ethanol, and the mix-
ture was allowed to reflux for 7 h. On cooling the reaction
mixture to room temperature, a white solid appeared. The
crude product was filtered off and recrystallized from
ethanol to give the desired compound 4.
2-[6-(Morpholin-4-yl)pyridin-3-ylamino
]acetohydrazide (4)
1
Elmer 1600 series FTIR spectrometer. H NMR and 13C
Yield (2.23 g, 89 %); m.p. 175–177 °C; IR (KBr, m, cm-1):
3341, 3301, 3189 (NH2?NH), 1,658 (C=O), 1,578 (C=N),
1,118 (C–O); 1H NMR (DMSO-d6, d ppm): 3.14 (t, 4H, N–
2CH2, J = 4.8 Hz), 3.77 (t, 4H, O–2CH2, J = 4.8 Hz),
4.00 (d, 2H, N–CH2, J = 6.4 Hz), 4.22 (s, 2H, NH2), 5.42
NMR spectra were registered on DMSO-d6 on a BRUKER
AVENE II 400 MHz NMR Spectrometer (400.13 MHz for 1H
and 100.62 MHz for 13C). The chemical shifts are given in
ppm relative to Me4Si as an internal reference; J values are
given in Hz. The elemental analysis was performed on a
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Med Chem Res (2013) 22:3629–3639
3635
Synthesis of compound 7
(s, 1H, NH), 5.57 (t, 1H, NH, J = 6.8 Hz), 6.65 (d, 1H,
arH, J = 8.4 Hz), 6.94 (m, 1H, arH), 7.56 (s, 1H, arH); 13
C
Compound 4 (10 mmol) and CS2 (6.0 mL, 10 mol) were
added to a solution of KOH (0.56 g, 10 mol) in 50 mL
H2O and 50 mL ethanol. The reaction mixture was refluxed
for 3 h. After evaporating in reduced pressure to dryness, a
solid was obtained. This was dissolved in 300 mL H2O and
acidified with conc. HCl. The precipitate was filtered off,
washed with H2O, and recrystallized from ethanol to afford
the desired compound.
NMR (DMSO-d6, d ppm): 45.22 (CH2), 47.42 (N–2CH2),
66.73 (O–2CH2), arC: [108.99 (CH), 123.83 (CH), 132.36
(CH), 138.70 (C), 151.71 (C)], 172.20 (C=O); LC–MS: m/z
(%) 252.29 [M?1]? (80), 164.12 (90); Anal.calcd (%) for
C11H17N5O2 : C, 52.58; H, 6.82; N, 27.87. Found: C,
52.55; H, 6.68; N, 27.95.
Syntheses of compounds 5 and 6
5-{[(6-Morpholin-4-ylpyridin-3-yl)amino]methyl}-
The solution of compound 4 (10 mmol) in absolute ethanol
was refluxed with appropriate aldehyde (10 mmol) for 6 h.
Then, the reaction content was allowed to cool to room
temperature, and a solid appeared. This crude product was
filtered off and recrystallized from ethanol to obtain the
desired compound.
1,3,4-oxadiazole-2-thiol (7)
Yield (2.08 g, 71 %); m.p. 221–222 °C; IR (KBr, t, cm-1):
3,299 (NH), 3,071 (Ar CH), 1,535 (C=N), 1,118 (C–O); 1H
NMR (DMSO-d6, d ppm): 3.20 (s, 4H, N–2CH2), 3.67 (s,
4H, O–2CH2), 4.35 (brs, 2H, CH2), 5.94 (bs, 1H, NH), 6.71
(d, 1H, arH, J = 7.4 Hz), 7.04 (d, 1H, arH, J = 9 Hz),
7.67 (s, 1H, arH), 13.45 (s, 1H, SH); 13C NMR (DMSO-d6,
d ppm): 38.44–41.36 (DMSO-d6?CH2), 47.15 (N–2CH2),
66.67 (O–2CH2), arC: [109.22 (CH), 124.70 (CH), 132.04
(CH), 137.20 (C), 150.45 (C)], 163.10 (oxadiazole C-2),
178.54 (oxadiazole C-5); LC–MS: m/z (%) 293.45 [M]?
(45), 294.75 [M?1]? (86), 165.23 (35); Anal.calcd (%) for
C12H15N5O2S: C, 49.13; H, 5.15; N, 23.87, S, 10.93.
Found: C, 49.25; H, 5.10; N, 23.90; S, 10.85.
N-(4-Bromobenzylidene)-2-[6-(morpholin-4-yl)pyridin-
3-ylamino]acetohydrazide (5)
Yield (3.43 g, 82 %); m.p. 163–164 °C; IR (KBr, m, cm-1):
3,307 (2NH), 1,687 (C=O), 1,590 (C=N), 1,121 (C–O); H
1
NMR (DMSO-d6, d ppm): 3.20 (brs, 4H, N–2CH2), 3.73
(brs, 4H, O–2CH2), 4.20 (brs, 2H, CH2), 6.73 (d, 1H, arH,
J = 8.6 Hz), 6.99–7.12 (m, 1H, NH), 7.60 (d, 6H, arH,
J = 6.2 Hz), 8.91 (s, 1H, N=CH), 11.58 (s, 1H, NH); 13C
NMR (DMSO-d6, d ppm): 45.93 (CH2), 56.72 (N–2CH2),
66.61 (O–2CH2), arC: [123.20 (C), 124.90 (C), 129.66
(CH), 130.01 (CH), 130.73 (CH), 130.98 (2CH), 132.51
(2CH), 136.25 (C), 138.16 (C)], 132.62 (N=CH), 166.12
(C=O); LC–MS: m/z (%) 418.66 [M]? (78), 265.12 (28);
Anal.calcd (%) for C18H20BrN5O2: C, 51.69; H, 4.82; N,
16.74. Found: C, 51.60; H, 4.75; N, 16.80.
Synthesis of compound 8
To the solution of corresponding compound 7 (10 mmol) in
dichloromethane, formaldehyde (37 %, 1.55 mL) and
phenyl piperazine (10 mmol) were added, and the mixture
was stirred at room temperature for 3 h. After removing the
solvent under reduced pressure, a solid was obtained. This
crude product was treated with water, filtered off, and
recrystallized from ethyl acetate/petroleum ether (1:2) to
yield the desired compound.
2-{[6-(Morpholin-4-yl)pyridin-3-yl]amino}-N-(3-
phenylallylidene)acetohydrazide (6)
Yield (3.18 g, 87 %); m.p. 194–195 °C; IR (KBr, m, cm-1):
3,208 (2NH), 1,666 (C=O), 1,554 (C=N), 1,120 (C–O); H
1
5-{[(6-Morpholin-4-ylpyridin-3-yl)amino]methyl}-3-[(4-
phenylpiperazin-1-yl)methyl]-1,3,4-oxadiazole-2(3H)-
thione (8)
NMR (DMSO-d6, d ppm): 3.19 (brs, 4H, N–2CH2), 3.67
(brs, 4H, O–2CH2), 4.08 (d, 2H, CH2, J = 5.2 Hz), 5.46 (s,
1H, CH), 6.69 (d, 1H, CH, J = 8.2 Hz), 6.99 (d, 3H,
arH?NH, J = 3.2 Hz), 7.35 (d, 3H, arH, J = 7.4 Hz), 7.61
(brs, 3H, arH), 7.91 (s, 1H, NH), 11.42 (s, 1H, NH); 13C
NMR (DMSO-d6, d ppm): 47.48 (CH2), 56.72 (N–2CH2),
66.75 (O–2CH2), arC: [125.83 (CH), 126.20 (CH), 127.76
(CH), 129.53 (CH), 132.51 (CH), 136.56 (C), 138.42 (CH),
139.62 (CH), 146.75 (CH), 153.22 (C), 167.52 (C)], 108.98
(CH), 123.84 (CH), 149.48 (N=CH), 172.00 (C=O); LC–
MS: m/z (%) 365.66 [M]? (75), 265.46 (56), 165.23 (90);
Anal.calcd (%) for C20H23N5O2: C, 65.74; H, 6.34; N,
19.16. Found: C, 65.82; H, 6.36; N, 19.22.
Yield (3.79 g, 81 %); m.p. 87–88 °C; IR (KBr, t, cm-1):
3,392 (NH), 1,599 (C=N), 1,118 (C–O); 1H NMR (DMSO-
d6, d ppm): 3.14 (s, 4H, N–2CH2), 3.79 (s, 4H, O–2CH2),
4.51 (brs, 2H, CH2), 4.86 (bs, 8H, 4CH2), 5.01 (s, 2H,
CH2), 5.43 (bs, 1H, NH), 6.61 (m, 1H, arH), 6.90 (m, 3H,
arH), 7.26 (m, 3H, arH), 8.03 (m, 1H, arH); 13C NMR
(DMSO-d6, d ppm): 46.33(N–CH2), 46.54 (N–CH2), 49.52
(N–2CH2), 50.16 (N–CH2), 50.59 (N–CH2), 66.97 (O–
2CH2), 70.28 (2CH2), arC: [107.98 (CH), 116.64 (2CH),
117.32 (CH), 120.39 (CH), 129.43 (2CH), 133.42 (C),
123

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Med Chem Res (2013) 22:3629–3639
136.29 (CH), 151.39 (C), 156.61 (C)], 173.47 (oxadiazole
C-2), 178.99 (oxadiazole C-5); LC–MS: m/z (%) 466.85
[M]? (54), 468.11 [M?1]? (36), 215.45(55); Anal.calcd
(%) for C23H29N7O2S: C, 59.08; H, 6.25; N, 20.97, S,
6.86. Found: C, 59.18; H, 6.20; N, 20.82; S, 6.88.
4H, O–2CH2, J = 4.8 Hz), 4.87 (s, 2H, CH2), 5.65 (s, 1H,
NH), 6.57 (d, 1H, CH, J = 8.6 Hz), 7.31 (m, 3H, arH),
7.44–7.57 (m, 6H, arH), 7.97 (d, 3H, arH, J = 8.6 Hz),
10.54 (s, 1H, NH); 13C NMR (DMSO-d6, d ppm): 41.19
(CH2), 47.15 (N–2CH2), 66.99 (O–2CH2), arC: [126.99
(2CH), 129.47 (2CH), 130.21 (2CH), 130.57 (2CH), 130.84
(2CH), 135.64 (2C), 134.05 (2CH), 136.24 (2C), 140.82
(C)], 125.83 (CH, tiyazol C-4), 152.30 (tiyazol C-2),
153.84 (tiyazol C-5), 192.20 (C=O); LC–MS: m/z (%)
521.25 [M]? (45), 215.45 (65), 165.45 (75); Anal.calcd
(%) for C26H25ClN6O2S: C, 59.94; H, 4.84; N, 16.13, S,
6.15. Found: C, 59.85; H, 4.78; N, 16.22; S, 6.18.
Synthesis of compound 9
The mixture of compound 4 (10 mmol) and phenylisothi-
ocyanate (10 mmol) in absolute ethanol was refluxed for
6 h. On allowing the reaction content to be cooled to room
temperature, a white solid was formed. This crude product
was filtered off and recrystallized from ethylacetate to
afford the desired compound.
Synthesis of compound 11
2-{[(6-Morpholin-4-ylpyridin-3-yl)amino]acetyl}-N-
A solution of compound 9 (10 mmol) in ethanol:water
(1:1) was refluxed in the presence of 2N NaOH for 3 h,
then, the resulting solution was cooled to room tempera-
ture, and acidified to pH 4 with 37 % HCl. The precipitate
formed was filtered off, washed with water, and recrys-
tallized from ethyl acetate to afford the desired compound.
phenylhydrazinecarbothioamide (9)
Yield (3.16 g, 82 %); m.p. 171–172 °C; IR (KBr, m, cm-1):
3,321 (2NH), 3,164 (2NH), 1,685 (C=O), 1,215 (C=S),
1
1,110 (C–O); H NMR (DMSO-d6, d ppm): 3.02 (bs, 4H,
N–2CH2), 3.58 (bs, 4H, O–2CH2), 3.82 (d, 2H, CH2,
J = 5.2 Hz), 5.85 (s, 1H, NH), 6.42–6.52 (m, 2H, arH),
6.92 (d, 2H, arH, J = 9.8 Hz), 7.26 (d, 2H, arH,
J = 9.4 Hz), 7.75 (bs, 2H, arH), 9.55 (s, 1H, NH), 9.72 (bs,
1H, NH), 10.42 (s, 1H, NH); 13C NMR (DMSO-d6,
d ppm): 45.32 (CH2), 55.54 (N–2CH2), 66.35 (O–2CH2),
arC: [101.52 (CH), 114.56 (CH), 125.83 (CH), 126.20
(CH), 128.24 (CH), 132.51 (CH), 136.56 (C), 138.42 (CH),
139.62 (CH), 146.75 (C), 153.22 (C)], 170.56 (C=O),
182.23 (C=S); LC–MS: m/z (%) 386.25 [M]? (68), 265.24
(66), 165.85 (87); Anal.calcd (%) for C18H22N6O2S: C,
55.94; H, 5.74; N, 21.75; S, 8.30. Found: C, 55.82; H, 5.82;
N, 21.62; S, 8.42.
5-[(6-Morpholin-4-ylpyridin-3-yl)methyl]-4-phenyl-
4H-1,2,4-triazole-3-thiol (11)
Yield (3.17 g, 87 %); m.p. 165–166 °C; IR (KBr, m, cm-1):
3,327 (NH), 3,093 (Ar CH), 2,857 (SH), 1,451 (C=N),
1,115 (C–O); 1H NMR (DMSO-d6, d ppm): 3.17 (s, 4H, N–
2CH2), 3.66 (s, 4H, O–2CH2), 4.06 (d, 2H, CH2,
J = 2.2 Hz), 5.51 (bs, 1H, NH), 6.68 (d, 1H, arH,
J = 6 Hz), 6.81 (d, 1H, arH, J = 4.0 Hz), 7.44 (bs, 2H,
arH), 7.52 (bs, 4H, arH), 13.91 (s, 1H, SH); 13C NMR
(DMSO-d6, d ppm): 38.90–41.41 (DMSO-d6?CH2), 47.27
(N–2CH2), 66.72 (O–2CH2), arC: [108.81 (CH), 124.04
(2CH), 128.74 (2CH), 130.05 (2CH), 132.70 (CH), 134.16
(C), 137.63 (C), 151.06 (C)], 153.48 (triazole C-3), 168.73
(triazole C-5); LC–MS: m/z (%) 368.22 [M]? (62), 165.45
(80); Anal.calcd (%) for C18H20N6OS: C, 58.68; H, 5.47;
N, 22.81, S, 8.70. Found: C, 58.72; H, 5.42; N, 22.80; S,
8.82.
Synthesis of compound 10
4-Chlorophenacylbromide (10 mmol) and dried sodium
acetate (16.4 g 200 mmol) was added to the solution of
compound 9 in absolute ethanol, and the reaction mixture
was refluxed for 7 h. Then, the mixture was cooled to room
temperature, poured into ice-cold water under stirring, and
left overnight in cold. The formed solid was filtered,
washed with water three times and recrystallized from
ethanol to afford compound 10.
Synthesis of compound 12
Concentrated sulfuric acid (64 mmol) was added into
compound 9 (10 mmol) drop by drop under stirring, and
the reaction content was stirred in an ice bath for 15 min.
The mixture was allowed to reach to room temperature and
stirred for an additional 3 h. Then, the resulting solution
was poured into ice-cold water and made alkaline to pH 8
with ammonia. The precipitated product was filtered,
washed with water, and recrystallized from ethanol to
afford the desired product.
N0-[(5-(4-Chlorophenyl)-3-phenyl-1,3-thiazol-2(3H)-
ylidene]-2-{(6-morpholin-4-ylpyridin-3-
yl)amino}acetohydrazide (10)
Yield (3.33 g, 64 %); m.p. 168–169 °C; IR (KBr, m, cm-1):
3,283 (2NH), 1,699 (C=O), 1,588 (C=N), 1,116 (C–O); H
1
NMR (DMSO-d6, d ppm): 3.34 (bs, 4H, N–2CH2), 3.81 (d,
123

Med Chem Res (2013) 22:3629–3639
3637
5-[(6-Morpholin-4-ylpyridin-3-yl)methyl]-N-phenyl-1,3,4-
pseudotuberculosis (Y. pseudotuberculosis) ATCC911,
Pseudomonas aeruginosa (P. aeruginosa) ATCC43288,
Enterococcus faecalis (E. faecalis) ATCC29212, Staphy-
lococcus aureus (S. aureus) ATCC25923, Bacillus cereus
(B. cereus) 709 Roma, Mycobacterium smegmatis
(M. smegmatis) ATCC607, Candida albicans (C. albicans)
ATCC60193, and Saccharomyces cerevisiae (S. cerevisia)
RSKK 251. All the newly synthesized compounds were
weighed and dissolved in hexane to prepare extract stock
solution of 20.000 microgram/milliliter (lg/mL).
The antimicrobial effects of the substances were tested
quantitatively in respective broth media by means of dou-
ble microdilution, and the minimal inhibition concentration
(MIC) values (lg/mL) were determined. The antibacterial
and antifungal assays were performed in Mueller–Hinton
broth (MH) (Difco, Detroit, MI) at pH.7.3 and buffered
Yeast Nitrogen Base (Difco, Detroit, MI) at pH 7.0,
respectively. The micro dilution test plates were incubated
for 18–24 h at 35 °C. Brain Heart Infusion broth (BHI)
(Difco, Detriot, MI) was used for M. smegmatis, and
incubated for 48–72 h at 35 °C (Woods et al., 2003).
Ampicillin (10 lg) and fluconazole (5 lg) were used as
standard antibacterial and antifungal drugs, respectively.
Dimethylsulfoxide with dilution of 1:10 was used as sol-
vent control. The results are presented in Table 1. Urease
inhibitory activity was determined according to Van Slyke
and Archibald (Van Slyke and Archibald, 1944), and the
results are shown in Table 2.
thiadiazol-2-amine (12)
Yield (2.13 g, 58 %); m.p. 172–173 °C; IR (KBr, m, cm-1):
3,252 (2NH), 3,077 (Ar CH), 1,599 (C=N), 1,121 (C–O);
1H NMR (DMSO-d6, d ppm): 3.49 (bs, 4H, N–2CH2), 3.66
(bs, 4H, O–2CH2), 4.49 (s, 2H, CH2), 6.04 (bs, 1H, NH),
7.26–7.34 (m, 4H, arH), 7.54–7.66 (m, 4H, arH), 10.23
(s,1H, NH); 13C NMR (DMSO-d6, d ppm): 34.63 (CH2),
47.18 (N–2CH2), 66.69 (O–2CH2), arC: [109.13 (CH),
117.93 (2CH), 122.42 (2CH), 125.33 (CH), 129.75 (2CH),
137.53 (C), 141.31 (C), 153.50 (C)], 161.75 (thiadiazole
C-2), 165.11 (thiadiazole C-5); LC–MS: m/z (%) 368.45
[M]? (56), 165.45 (85); Anal.calcd (%) for C18H20N6OS:
C, 58.68; H, 5.47; N, 22.81, S, 8.70. Found: C, 58.74; H,
5.55; N, 22.85; S, 8.75.
Synthesis of compound 13
Ethyl bromoacetate was added to the solution of compound
9 in absolute ethanol (10 mmol), and the mixture was
refluxed in the presence of dried sodium acetate (16.4 g
200 mmol) for 9 h. Then, the mixture was cooled to room
temperature, poured into ice-cold water under stirring, and
left overnight in cold. The formed solid was filtered,
washed with water three times, and recrystallized from
benzene-petroleum ether (1:2) to afford the pure compound.
2-[(6-Morpholin-4-ylpyridin-3-yl)amino]-N’-(4-oxo-3-
Open Access This article is distributed under the terms of the
Creative Commons Attribution License which permits any use, dis-
tribution, and reproduction in any medium, provided the original
author(s) and the source are credited.
phenyl-1,3-thiazolidin-2-ylidene)acetohydrazide (13)
Yield (3.33 g, 45 %); m.p. 201–202 °C; IR (KBr, m, cm-1):
3,326 (2NH), 1,746 (2C=O), 1,492 (C=N), 1,119 (C–O);
1H NMR (DMSO-d6, d ppm): 3.17 (bs, 4H, N–2CH2), 3.67
(bs, 4H, O–2CH2), 3.86 (d, 2H, CH2, J = 3.8 Hz), 4.18 (s,
2H, S–CH2), 5.74 (bs, 1H, NH), 6.89–7.16 (m, 5H, arH),
7.32–7.38 (m, 3H, arH), 10.86 (s, 1H, NH); 13C NMR
(DMSO-d6, d ppm): 30.61 (NH–CH2), 45.58 (thiazolidine-
CH2), 56.28 (N–2CH2), 66.64 (O–2CH2), arC: [107.12
(CH), 108.79 (CH), 121.52 (CH), 124.15 (CH), 125.19
(CH), 126.52 (C), 129.52 (CH), 130.02 (CH), 132.84 (CH),
138.32 (C), 148.02 (C)], 152.30 (thiazolidine C-2), 158.39
(thiazolidine C-4), 170.94 (C=O); LC–MS: m/z (%) 426.52
[M]? (52), 215.86 (64), 165.42 (74); Anal.calcd (%) for
C20H22N6O3S: C, 56.32; H, 5.20; N, 19.70, S, 7.52. Found:
C, 56.42; H, 5.32; N, 19.65; S, 7.62.
References
Adil M, Aslama S, Mahmoodb S, Shahidc M, Saeedb A, Iqbala J
(2011) Synthesis, biological assay in vitro and molecular
docking studies of new Schiff base derivatives as potential
urease inhibitors. Eur J Med Chem 46:5473–5479
Aktay G, Tozkoparan B, Ertan M (2009) Investigation of antioxidant
properties of some 6-(a-aminobenzyl)thiazolo[3,2-b]-1,2,4-tria-
zole-5-ol compounds. J Enzym Inhib Med Chem 24:898–902
Amtul Z, Rahman A, Siddiqui RA, Choudhary MI (2002) Chemistry and
mechanism of urease inhibition. Curr Med Chem 9:1323–1348
Amtul Z, Rasheed M, Choudhary MI, Supino R, Khan KM, Rahman
A (2004) Kinetics of novel competitive inhibitors of urease
enzymes by a focused library of oxadiazoles/thiadiazoles and
triazoles. Biochem Biophys Res Commun 319:1053–1057
Andres CJ, Bronson JJ, Andrea SVD, Deshpande MS, Falk PJ, Grant-
Young KA, Harte WE, Ho HT, Misco PF, Robertson JG, Stock D,
Sun Y, Walsh AW (2000) 4-Thiazolidinones: novel inhibitors of
the bacterial enzyme murB. Bioorg Med Chem Lett 10:715–717
Aridoss G, Balasubramanian GAS, Parthiban P, Kabilan S (2007)
Synthesis, stereochemistry and antimicrobial evaluation of some
N-morpholinoacetyl-2,6-diarylpiperidin-4-ones. Eur J Med Chem
42:851–860
Antimicrobial activity
All test microorganisms were obtained from the Hifzissihha
Institute of Refik Saydam (Ankara, Turkey) and were as
follows: Escherichia coli (E. coli) ATCC35218, Yersinia
123

3638
Med Chem Res (2013) 22:3629–3639
Ashiralieva A, Kleiner
D
(2003) Polyhalogenated benzo- and
triazole derivatives and investigation of their antimicrobial
activities. Eur J Med Chem 44:2896–2903
Dixit PP, Nair PS, Patil VJ, Jain S, Arora SK, Sinha N (2005)
Synthesis and antibacterial activity of novel (un)substituted
benzotriazolyl oxazolidinone derivatives. Bioorg Med Chem
Lett 15:3002–3005
Dixit PP, Patil VJ, Nair PS, Jain S, Sinha N, Arora SK (2006)
Synthesis of 1-[3-(4-benzotriazol-1/2-yl-3-fluoro-phenyl)-2-oxo-
oxazolidin-5-ylmethyl]-3-substituted-thiourea derivatives as
antituberculosis agents. Eur J Med Chem 41:423–428
naphthoquinones are potent inhibitors of plant and bacterial
ureases. FEBS Lett 555:367–370
Ashok M, Holla BS, Poojary B (2007) Convenient one pot synthesis and
antimicrobial evaluation of some new Mannich bases carrying
4-methylthiobenzyl moiety. Eur J Med Chem 42:1095–1101
Bachmeier KL, Williams AE, Warmington JR, Bang SS (2002)
Urease activity in microbiologically-induced calcite precipita-
tion. J Biotechnol 93:171–181
Barreca ML, Chimirri A, Luca LD, Monforte A, Monforte P, Rao A,
Zappala M, Balzarini J, De Clercq E, Pannecouque C, Witvrouw
M (2001) Discovery of 2,3-diaryl-1,3-thiazolidin-4-ones as
potent anti-HIV-1 agents. Bioorg Med Chem Lett 11:1793–1796
Bayrak H, Demirbas A, Demirbas N, Alpay Karaoglu S (2009a)
Synthesis of some new 1,2,4-triazoles starting from isonicotinic
acid hydrazide and evaluation of their antimicrobial activities.
Eur J Med Chem 44:4362–4366
Bayrak H, Demirbas A, Alpay Karaoglu S, Demirbas N (2009b)
Synthesis of some new 1,2,4-triazoles, their Mannich and Schiff
bases and evaluation of their antimicrobial activities. Eur J Med
Chem 44:1057–1066
Bayrak H, Demirbas A, Demirbas N, Alpay Karaoglu S (2010a)
Cyclization of some carbothioamide derivatives containing
antipyrine and triazole moieties and investigation of their
antimicrobial activities. Eur J Med Chem 45:4726–4732
Bayrak H, Demirbas A, Bektas H, Alpay Karaoglu S, Demirbas N
(2010b) Synthesis and antimicrobial activities of some new
1,2,4-triazole derivatives. Turk J Chem 34:835–846
´
´
Domınguez MJ, Sanmartın C, Font M, Palop JA, Francisco SS,
Urrutia O, Houdusse F, Garci ca-Mina J (2008) Design,
synthesis, and biological evaluation of phosphoramide deriva-
tives as urease inhibitors. J Agric Food Chem 56:3721–3731
Duruibe JO, Ogwuegbu MOC, Egwurugwu JN (2007) Heavy metal
pollution and human biotoxic effects. Int J Phys Sci 2:112–118
Dye C, Phill D (2006) Global epidemiology of tuberculosis. The
Lancet 367:938–940
Dye C, Williams BG (2009) Slow elimination of multidrug-resistant
tuberculosis. Transl Med 1(3):3–8
El-Gaby MSA, El-Hag Ali GAMA, El-Maghraby A, Abd El-Rahman
MT, Helal MHM (2009) Synthesis, characterization and in vitro
antimicrobial activity of novel 2-thioxo-4-thiazolidinones and
4,40-bis(2-thioxo-4-thiazolidinone-3-yl)diphenylsulfones. Eur J
Med Chem 44:4148–4152
Gage JG, Perrault WP, Poel TJ, Thomas RC (2000) Stereodivergent
synthesis of sulfoxide-containing oxazolidinone antibiotics.
Tetrahedron Lett 41:4301–4305
Bekircan O, Ozen T, Gumrukcuoglu N, Bektas H (2008) Synthesis
and antioxidant properties of some new 3-(4-chlorophenyl)-5-
(pyridin-4-yl)-4H-1,2,4-triazole derivatives. Z Naturforsch 63:
548–554
Giera R, Cantos-Llopart C, Amat M, Bosch J, del Castillo JC, Huguet
(2006) New potential antibacterials: a synthetic route to N-
aryloxazolidinone/3-aryltetrahydroisoquinoline hybrids. Bioorg
Med Chem Lett 16:529–531
Bektas H, Karaali N, Sahin D, Demirbas A, Alpay Karaoglu S,
Demirbas N (2010) Synthesis and antimicrobial activities of
some new 1,2,4-triazole derivatives. Molecules 15:2427–2438
Bektas H, Demirbas A, Demirbas N, Alpay Karaoglu S (2012)
Synthesis and biological activity studies of new hybrid mole-
cules containing tryptamine moiety. Med Chem Res 21:212–223
Bonde CG, Gaikwad NJ (2004) Synthesis and preliminary evaluation
of some pyrazine containing thiazolines and thiazolidinones as
antimicrobial agents. Bioorg Med Chem 12:2151–2161
Cai S, Li QS, Borchardt RT, Kuczera K, Schowen RL (2007) The
antiviral drug ribavirin is a selective inhibitor of S-adenosyl-L-
homocysteine hydrolase from Trypanosoma cruzi. Bioorg Med
Chem 15:7281–7287
Capan G, Ulusoy N, Ergenc N, Kiraz M (1999) New 6-phenylim-
idazo[2,1-b]thiazole derivatives: synthesis and antifungal activ-
ity. Monatsh Chem 130:1399–1407
Cheng K, Zheng QZ, Zhu HL (2009) Syntheses, structures and urease
inhibitory activities of mononuclear cobalt(III) and 1D cobalt(II)
complexes with ligands derived from 3-formylsalicylic acid.
Inorg Chem Commun 12:1116–1119
Cobena AS, Misselbrook TH, Arce A, Mingot JI, Diez JA, Vallejo A
(2008) An inhibitor of urease activity effectively reduces
ammonia emissions from soil treated with urea under Mediter-
ranean conditions. Agric Ecosyst Environ 126:243–249
Cui Y, Dang Y, Yang Y, Zhang S, Ji R (2005) Syntheses and
antibacterial activity of a series of 3-(pyridine-3-yl)-2-oxazolid-
inone. Eur J Med Chem 40:209–214
Das B, Rudra S, Yadav A, Ray A, Rao AVSR, Srinivas ASSV, Saini
S, Shukla S, Pandya M, Bhateja P, Malhotra S, Mathur T, Arora
SK, Rattan A, Metha A (2005) Synthesis and SAR of novel
oxazolidinones: discovery of ranbezolid. Bioorg Med Chem Lett
15:4261–4267
Gupta A, Unadkat JD, Mao Q (2007) Interactions of azole antifungal
agents with the human breast cancer resistance protein (BCRP).
J Pharm Sci 96:3226–3235
Hancu G, Gaspar A, Gyeresi A (2007) Separation of 1,4-ben-
zodiazepinesby micellar electrokinetic capillary chromatogra-
phy. J Biochem Biophys Methods 69:251–259
Ito Y, Shibata K, Hongo A, Ecabet KinoshitaM (1998) Sodium, a
locally acting antiulcer drug, inhibits urease activity of Helico-
bacter pylori. Eur J Pharm 345:193–198
Khan KM, Wadood A, Ali M, Ullah Z, Ul-Haq Z, Lodhi MA, Khan
M, Perveen S, Choudhary MI (2010a) Identification of potent
urease inhibitors via ligand- and structure-based virtual screen-
ing and in vitro assays. J Mol Graph Model 28:792–798
Khan I, Ali S, Hameed S, Rama NH, Hussain MT, Wadood A, Uddin R,
Ul-Haq Z, Khan A, Ali S, Choudhary MI (2010b) Synthesis,
antioxidant activities and urease inhibition of some new 1,2,4-triazole
and 1,3,4-thiadiazole derivatives. Eur J Med Chem 45:5200–5207
¨
¨
Koca M, Servi S, Kirilmis C, Ahmedzade M, Kazaz C, Ozbek B, Otu¨k
G (2005) Synthesis and antimicrobial activity of some novel
derivatives of benzofuran: part 1. Synthesis and antimicrobial
activity of (benzofuran-2yl) (3-phenyl-3-methylcyclobutyl) ket-
oxime derivatives. Eur J Med Chem 40:1351–1358
Kot M, Zaborska W, Orlinska K (2001) Inhibition of jack bean urease
by N-(n-butyl)thiophosphorictriamide and N-(n-butyl)phos-
phorictriamide: determination of the inhibition mechanism.
J Enzym Inhib Med Chem 16:507–516
Kot M, Karcz W, Zaborska W (2010) 5-Hydroxy-1,4-naphthoquinone
(juglone) and 2-hydroxy-1,4-naphthoquinone (lawsone) influ-
ence on jack bean urease activity: elucidation of the difference in
inhibition activity. Bioorg Chem 38:132–137
Krajewska B (2009) Ureases I. Functional, catalytic and kinetic
properties: a review. J Mol Catal B Enzym 59:9–21
Demirbas A, Sahin D, Demirbas N, Alpay Karaoglu S (2009)
Synthesis of some new 1,3,4-thiadiazol-2-ylmethyl-1,2,4-
Kreybig T, Preussmann R, Schmidt W (1968) Chemical constitution
and teratogenic effect in rats. I. Carbonic acid amides, carbonic
123

Med Chem Res (2013) 22:3629–3639
3639
acid hydrazides and hydroxamic acids. Arzneim Forsch 18:
645–657
¨
Ku¨c¸u¨kgu¨zel SG, Oruc¸ EE, Rollas S, S¸ahin F, Ozbek A (2002)
Van Slyke DD, Archibald RM (1944) Monometric, titrimetric and
colorimetric methods for measurements of urease activity. J Biol
Chem 154:623–642
Synthesis, characterisation and biological activity of novel
4-thiazolidinones, 1,3,4-oxadiazoles and some related com-
pounds. Eur J Med Chem 37:197–206
Vicini P, Geronikaki A, Incerti M, Zani F, Dearden J, Hewitt M
(2008) 2-Heteroarylimino-5-benzylidene-4-thiazolidinones ana-
logues of 2-thiazolylimino-5-benzylidene-4-thiazolidinones with
antimicrobial activity: synthesis and structure–activity relation-
ship. Bioorg Med Chem 16:3714–3724
Weidner-Wells MA, Broggs CM, Foleno BD, Melton J, Bush K,
Goldshmidt RM, Hlasta D (2002) Novel piperidinyloxy oxazo-
lidinone antibacterial agents. Diversification of the N-substituent.
Bioorg Med Chem 10:2345–2351
Woods GL, Brown-Elliott BA, Desmond EP, Hall GS, Heifets L,
Pfyffer GE, Ridderhof JC, Wallace RJ, Warren NC, Witebsky
FG (2003) Susceptibility testing of mycobacteria, nocardiae,
and other aerobic actinomycetes. App Stand NCCLS document
M24-A: 18–23
Wyrzykiewicz E, Wendzonka M, Kedzi B (2006) Synthesis and
antimicrobial activity of new (E)-4-[piperidino (40-methylpiperi-
dino-, morpholino-) N-alkoxy]stilbenes. Eur J Med Chem 41:
519–525
Matsubara S, Shibata H, Ishikawa F, Yokokura T, Takahashi M,
Sugimura T (2003) Suppression of Helicobacter pylori-induced
gastritis by green tea extract in Mongolian gerbils. Biochem
Biophys Res Commun 310:715–719
Muri EMF, Mishra H, Avery MA, Williamson JS (2003) Design and
synthesis of heterocyclic hydroxamic acid derivatives as inhibitors
of Helicobacter pylori urease. Synth Commun 33:1977–1995
National Committee for Clinical Laboratory Standard (1999) Methods
for determining bactericidal activity of antimicrobial agents, App
Guid NCCLS, Willanova, M26-A: 18–19
Panneerselvam P, Nair RR, Vijayalakshimi G, Subramanian EH,
Sridhar SK (2005) Synthesis of Schiff bases of 4-(4-aminophe-
nyl)-morpholine as potential antimicrobial agents. Eur J Med
Chem 40:225–229
Rao BM, Sangaraju S, Srinivasu MK, Madhavan P, Devi ML, Kumar
PR, Candrasekhar P, Arpitha C, Balaji TS (2006) Development
and validation of a specific stability indicating high performance
liquid chromatographic method for rizatriptan benzoate. J Pharm
Biomed Anal 41:1146–1151
Xiao ZP, Maa TW, Fu WC, Peng XC, Zhang AH, Zhu HL (2010) The
synthesis, structure and activity evaluation of pyrogallol and
catechol derivatives as Helicobacter pylori urease inhibitors. Eur
J Med Chem 45:5064–5070
Raparti V, Chitre T, Bothara K, Kumar V, Dangre S, Khachane C,
Gore S, Deshmane B (2009) Novel 4-(morpholin-4-yl)-N0-
(arylidene)benzohydrazides: synthesis, antimycobacterial activ-
ity and QSAR investigations. Eur J Med Chem 44:3954–3960
Sahin D, Bayrak H, Demirbas A, Demirbas N, Alpay-Karaoglu S
(2011) Design and synthesis of some azole derivatives as
potential antimicrobial agents. Med Chem Res. doi:10.1007/
s00044-012-9992-2
Yamashita Y, Kawada SZ, Nakaro H (1990) Competitive binding of
7-substituted-2,3-dichlorodibenzo-p-dioxins with human placen-
tal Ah receptor-A QSAR analysis. Biochem Pharmacol 39:
737–744
You ZL, Zhang L, Shi DH, Wang XL, Li XF, Ma YP (2010)
Synthesis, crystal structures and urease inhibitory activity of
copper(II) complexes with Schiff bases. Inorg Chem Commun
13:996–998
Schiller SD, Fung HB (2007) Posaconazole: an extended-spectrum
triazole antifungal agent. Clin Ther 29:1862–1886
Shi DH, You ZL, Xu C, Zhang Q, Zhu HL (2007) Synthesis, crystal
structure and urease inhibitory activities of Schiff base metal
complexes. Inorg Chem Commun 10:404–406
Shin JE, Kim JM, Bae EA, Hyun YJ, Kim DH (2005) In Vitro
Inhibitory Effect of Flavonoids on Growth, Infection and
Vacuolation of Helicobacter pylori. Planta Med 71:197–201
Srivastava BK, Jain MR, Solanki M, Soni R, Valani D, Gupta S,
Mishra B, Takale V, Kapadnis P (2008) Synthesis and in vitro
antibacterial activities of novel oxazolidinones. Eur J Med Chem
43:683–693
Yu LT, Ho MT, Chang CY, Yang TK (2007) Asymmetric zinc-
Reformatsky reaction of evans chiral imide with acetophenones
and its application to the stereoselective synthesis of triazole
antifungal agents. Tetrahedron Asymmetry 18:949–962
Zalavadiya P, Tala S, Akbari J, Joshi H (2009) Multi-component
synthesis of dihydropyrimidines by iodine catalyst at ambient
temperature and in vitro antimycobacterial activity. Arch Pharm
342:469–475
Zheng QZ, Cheng K, Zhang XM, Liu K, Jiao QC, Zhu HL (2010)
Synthesis of some N-alkyl substituted urea derivatives as
antibacterial and antifungal agents. Eur J Med Chem 45:
3207–3212
123