Activity of ring-substituted 8-hydroxyquinoline-2-carboxanilides against intestinal sulfate-reducing bacteria Desulfovibrio piger

Article abstract of DOI:10.1007/s00044-017-2067-7

Desulfovibrio genus is dominant among sulfate-reducing bacteria (SRB) in the large intestine of healthy people and animals. It is mostly isolated from patients with inflammatory bowel disease (IBD) and can be involved in the disease initiation. Primary in vitro screening of 8-hydroxyquinoline-2-carboxanilides was performed against Desulfovibrio piger Vib-7 representing SRB. The most effective compounds with MIC₉₀/MBC values in the range of 17–23 μM/20–23 μM, respectively, were substituted in C’₍₃₎ by CF₃, OCH₃, CH₃ and in C’₍₄₎ by CF₃. Their activity was twofold higher than that of ciprofloxacin. These compounds did not express any significant cytotoxic effect on THP-1 cells up to the tested concentration of 30 μM. The antibacterial efficacy of the most active C’₍₃₎-substituted compounds practically did not change with increasing compound lipophilicity, indicating that this position of substitution is favorable for significant antimicrobial effect, while the antibacterial activity of most of C’₍₂₎ and C’₍₄₎-substituted derivatives decreased linearly with increasing compound lipophilicity. In addition, the dependence of activity on electronic Hammett’s σ parameter of the substituent R was quasi-parabolic for the most effective C’₍₃₎-substituted compounds.

Full text of DOI:10.1007/s00044-017-2067-7

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-017-2067-7
ORIGINAL RESEARCH
Activity of ring-substituted 8-hydroxyquinoline-2-carboxanilides
against intestinal sulfate-reducing bacteria Desulfovibrio piger
2
Ivan Kushkevych1 Jiri Kos2 Peter Kollar3 Katarina Kralova4 Josef Jampilek
●
●
●
●
Received: 30 June 2017 / Accepted: 5 September 2017
© Springer Science+Business Media, LLC 2017
Abstract Desulfovibrio genus is dominant among sulfate-
reducing bacteria (SRB) in the large intestine of healthy
people and animals. It is mostly isolated from patients with
inflammatory bowel disease (IBD) and can be involved in
the disease initiation. Primary in vitro screening of 8-
hydroxyquinoline-2-carboxanilides was performed against
Desulfovibrio piger Vib-7 representing SRB. The most
effective compounds with MIC90/MBC values in the range
of 17–23 µM/20–23 µM, respectively, were substituted in
C’(3) by CF3, OCH3, CH3 and in C’(4) by CF3. Their activity
was twofold higher than that of ciprofloxacin. These com-
pounds did not express any significant cytotoxic effect on
THP-1 cells up to the tested concentration of 30 µM. The
antibacterial efficacy of the most active C’(3)-substituted
compounds practically did not change with increasing
compound lipophilicity, indicating that this position of
substitution is favorable for significant antimicrobial effect,
while the antibacterial activity of most of C’(2) and C’(4)-
substituted derivatives decreased linearly with increasing
compound lipophilicity. In addition, the dependence of
activity on electronic Hammett’s σ parameter of the sub-
stituent R was quasi-parabolic for the most effective C’(3)-
substituted compounds.
●
Keywords 8-Hydroxyquinolines Sulfate-reducing
●
●
●
bacteria Lipophilicity Electronic parameter
Structure–activity relationships
Introduction
The species of Desulfovibrio genus are dominant among
sulfate-reducing bacteria (SRB) and common inhabitants of
the human and animal large intestine, capable of dissim-
ilatory sulfate reduction (Gibson et al. 1991, 1993; Kush-
kevych 2015a, b; Kushkevych et al. 2015a, b; Wegmann
et al. 2017). These microorganisms are the most isolated
from patients with inflammatory bowel disease (IBD) and
can be involved in the disease initiation caused by their
main metabolite hydrogen sulfide, which is an inhibitor of
butyrate oxidation in colonocytes. In addition, it is cyto-
toxic, mutagenic and cancerogenic to epithelial intestinal
cells, which leads to the damage of the epithelial barrier
function, resulting in inflammatory responses characteristic
for IBD (Kushkevych et al. 2014; Pitcher and Cummings
1996; Zinkevich and Beech 2000). Therefore, the associa-
tion between SRB and IBD, such as ulcerative colitis (UC),
was hypothesized (Zinkevich and Beech 2000; Rowan et al.
2009; Loubinoux et al. 2002; Kushkevych 2014; Cummings
et al. 2003). Over 1 million residents in the USA and 2.5
million in Europe are estimated to have IBD, with sub-
stantial costs for health care, whereas these estimates do not
* Ivan Kushkevych
ivan.kushkevych@gmail.com
* Josef Jampilek
josef.jampilek@gmail.com
1
Department of Experimental Biology, Faculty of Science, Masaryk
University, Kamenice 753/5, 625 00 Brno, Czech Republic
2
Department of Pharmaceutical Chemistry, Faculty of Pharmacy,
Comenius University, Odbojarov 10, 832 32 Bratislava, Slovakia
3
Department of Human Pharmacology and Toxicology, Faculty of
Pharmacy, University of Veterinary and Pharmaceutical Sciences,
Palackeho 1, 612 42 Brno, Czech Republic
4
Institute of Chemistry, Faculty of Natural Sciences, Comenius
University, Ilkovicova 6, 842 15 Bratislava, Slovakia

Med Chem Res
factor in the ‘real’ price of IBD, which can impede career
aspirations, instil social stigma and impair quality of life in
patients (Kaplan 2015). Unlike Crohn’s disease, UC occurs
only in the large bowel, where bacteria amount is greater
than in the rest of the gut and also where the rate of passage
of material is characterized by slow movement of digestive
materials. Both acute and chronic forms of UC affect the
colon and rectum and can be a highly uncomfortable con-
dition (Cummings et al. 2003). UC usually has a relapsing/
remitting pattern and current medical approaches focus on
treating active disease to address symptoms, to improve the
quality of life and thereafter to maintain remission. Diarrhea
accompanied with blood, an urgent need to defecate and
abdominal pain are the main symptoms of active disease or
relapse. The reported incidence is 1.2 to 20.3 cases per
100,000 persons per year, and the prevalence is 7.6 to 245
cases per 100,000 per year (Feuerstein and Cheifetz 2014;
Cesar da Silva et al. 2014).
against Desulfovibrio piger Vib-7 representing SRB. D.
piger is a Gram-negative strict anaerobe that is usually
considered as a commensal bacterium in humans. More
recently, it has attracted more interest as it was found to be
the most prevalent species of SRB in feces of patients with
IBDs (Kushkevych 2014; Barton and Hamilton 2010; Holt
et al. 1994).
Material and methods
Synthesis
The discussed 8-hydroxyquinoline-2-carboxanilides 1–8c
(see Table 1) were synthesized previously (Kos et al. 2015a)
by means of microwave-assisted synthesis. The compounds
were fully characterized by melting point, infrared, nuclear
magnetic resonance, and high-resolution mass spectrometry
(Kos et al. 2015a).
The benefits of antibiotic therapy in UC are mediated by
different mechanisms, such as decreasing the concentration
of luminal bacteria, altering the composition of gut micro-
flora, decreasing bacterial tissue invasion and decreasing
bacterial translocation and systemic dissemination. Anti-
biotics have been prescribed for UC, however, they have
been largely ineffective (Cummings et al. 2003; Garud and
Peppercorn 2009). For example, the study of the in vitro
activities of rifaximin and comparator agents against 536
anaerobic intestinal bacteria performed by Finegold et al.
showed that the overall MICs90 of rifaximin for 90% the
tested strains were 338 μM, an activity equivalent to those
of teicoplanin and vancomycin (Finegold et al. 2009).
Nakao et al. (2009) tested the antimicrobial susceptibilities
of 23 strains of Desulfovibrio spp. and found that they were
susceptible to sulbactam-ampicillin, meropenem, clin-
damycin, and metronidazole with MIC90 corresponding to
17, 10, 0.45, and 1.46 μM, respectively. On the other hand,
Lozniewski et al. (2001) tested the antimicrobial suscept-
ibilities of 16 clinical isolates of Desulfovibrio spp. and
found that these isolates were resistant to piperacillin-
tazobactam, cefoxitin and cefotetan with MIC90 corre-
sponding to 495, >600 and 111 μM, respectively.
Therefore, it is necessary to study new antibacterial agents
in order to improve the treatment and discover alternative
therapeutics.
In vitro antibacterial susceptibility testing
The synthesized compounds were evaluated for in vitro
antibacterial activity against the intestinal SRB Desulfovi-
brio piger Vib-7 (Genbank: KT881309.1) that were isolated
from the healthy human large intestine as described pre-
viously (Kushkevych 2013; Kushkevych et al. 2014). The
strain has been kept in the collection of microorganisms at
the Department of Molecular Biology and Pharmaceutical
Biotechnology of the Faculty of Pharmacy at the University
of Veterinary and Pharmaceutical Sciences Brno (Czech
Republic). Ciprofloxacin (Sigma-Aldrich) was used as the
standard. Prior to testing, the strain at exponential phase
growth was passaged onto nutrition modified Kravtsov-
Sorokin’s (KS) agar medium (Kushkevych and Moroz
2012). Bacterial inocula were prepared by suspending a
small portion of bacterial colony in sterile KS liquid med-
ium (pH 7.5). Before bacterial passage in the medium, 10
mL/L of sterile Mohr’s salt solution [(NH4)SO4Fe
(SO4)2·6H2O] (10%) for visual detecting colonies of the
SRB was added. A culture sample (10 mL) was centrifuged
at 15,000 rpm/20 min using a bench top centrifuge (Model
CR 4-12, Jouan Inc., Winchester, VA, USA). Following
removal of the supernatant, the pellet was washed in fresh
liquid KS and re-suspended in fresh supplemented KS (10
mL). The turbidity was adjusted to match McFarland stan-
dard No. 1 (5 × 106 cfu) with KS using a densitometer
(Densi-La-Meter, LIAP, Latvia). The final inoculum was
made to a 1:20 dilution of the suspension with KS liquid
medium. The antimicrobial susceptibility of SRB was
investigated in a 96-well plate format. In these experiments,
sterile KS (300 µL) was added to all outer-perimeter wells
of the plates to minimize evaporation of the medium in the
This paper follows our recently published articles dealing
with the spectrum of biological activities of hydroxy-
quinoline-based compounds (Jampilek et al. 2005; Musiol
et al. 2006, 2007, 2008, 2010; Mrozek-Wilczkiewicz et al.
2010; Gonec et al. 2012; Cieslik et al. 2012, 2015;
Kos et al. 2015a; Jampilek et al. 2016). This study is
focused on the investigation of the efficacy and searching
for the structure–activity relationships within a series of
8-hydroxyquinoline-2-carboxanilides (Kos et al. 2015a)

Med Chem Res
Table 1 Experimentally determined values of lipophilicity log k,
predicted electronic Hammett’s σ parameters of substituents R, in vitro
72 h of static incubation in the darkness at 37 °C under
anaerobic conditions. In the process of bacterial growth,
hydrogen sulfide was formed and interacted with Fe2+ from
Mohr’s salt. As a result, FeS was formed by the bacterial
cells that caused black colored colonies that was interpreted
as a presence of bacterial growth. The medium dilution
micro-method modified according to NCCLS guidelines
(CLSI 2012, 2014) in KS medium was used to determine
the minimum inhibitory concentration (MIC90), the inhibi-
tory concentration (IC50) and minimum bactericidal con-
centration (MBC). Drug-free controls, sterility controls and
controls consisted of KS medium and DMSO alone were
included. The MICs were defined as the lowest concentra-
tion of the compound at which no visible bacterial growth
was observed. The IC50 values were defined as the com-
pound concentration causing 50% inhibition of bacterial
growth and the MBCs were defined as the lowest con-
centration of the compound at which an antimicrobial agent
kills a bacteria (CLSI 2012, 2014). The results are sum-
marized in Table 1.
antibacterial activity against Desulfovibrio piger Vib-7 (MIC, IC50
,
MBC) of the compounds in comparison with ciprofloxacin (CPX)
standard
Compounds R1
log ka σb
MIC90 IC50
MBC
[μM]
[μM] [μM]
1
H
0.7600
2-OCH3 0.7935 −0.28
3-OCH3 0.8164 0.12
0
23
12
25
2a
2b
2c
3a
3b
3c
4a
4b
4c
5a
5b
5c
6a
6b
6c
7a
7b
7c
8a
8b
8c
CPX
a
28
17
28
17
11
20
4-OCH3 0.7129 −0.27
2-CH3 0.6944 −0.17
3-CH3 0.9686 −0.07
4-CH3 0.9521 −0.17
557
44
380
15
557
48
23
10
23
75
40
80
2-F
0.6806
0.9420
0.8598
0.9566
1.1718
1.1543
1.0536
1.2357
1.2347
0.9147
1.3206
1.3653
0.06
0.34
0.06
0.22
0.37
0.23
0.22
0.39
0.23
0.51
0.43
0.51
0.77
0.71
0.78
–
90
50
95
3-F
45
20
50
Results and discussion
4-F
60
28
60
2-Cl
3-Cl
4-Cl
2-Br
3-Br
4-Br
2-CF3
3-CF3
4-CF3
120
50
95
123
55
In the previous studies it was confirmed that 2-substituted 8-
hydroxyquinolines are promising antimicrobial agents
(Jampilek et al. 2005; Musiol et al. 2006, 2010; Darby and
Nathan 2010; Gonec et al. 2012; Cieslik et al. 2012; 2015;
Kos et al. 2015a). Based on these observations, 8-
hydroxyquinoline-2-carboxanilides prepared according to
Scheme 1 and described recently (Kos et al. 2015a) were
tested against Desulfovibrio piger Vib-7. The testing was
performed according to Kushkevych et al. (2016).
The antibacterial potency of ring-substituted 8-
hydroxyquinoline-2-carboxanilides was expressed as the
MICs, IC50 values and MBCs, see Table 1. The activity of
the most potent compounds 7b (R = 3-CF3; MIC = 17 µM,
IC50 = 10 µM, MBC = 20 µM), 7c (R = 4-CF3; MIC = 20
µM, IC50 = 10 µM, MBC = 22 µM) and 2b (R = 3-OCH3;
MIC = 17 µM, IC50 = 11 µM, MBC = 20 µM) was twofold
higher that of the clinically used drug ciprofloxacin (MIC =
MBC = 45 µM) that was used as the standard. Also other
compounds such as 3b (R = 3-CH3; MBC = 23 µM), 1
(R = H; MBC = 25 µM), 2a (R = 2-OCH3; MBC = 28
µM), and 5b (R = 3-Br; MBC = 35 µM) were effective in
killing D. piger Vib-7. It is also important to note that no
significant cytotoxic effect of these compounds on THP-1
cells up to tested concentration 30 µM was observed (Kos
et al. 2015a).
20
480
150
33
330
103
18
486
150
35
337
48
225
35
340
50
17
10
20
20
10
22
2-NO2 1.1277
3-NO2 0.9845
4-NO2 1.0495
197
237
223
45
134
218
165
28
202
240
225
45
–
–
Experimental procedure described in Kos et al. (2015a)
Predicted using sw. ACD/Percepta ver. 2012
b
test wells during incubation. Sample wells were composed
of 100 µL of test compound dilution and 100 µL of the
bacterial stock being tested against. The compounds were
dissolved in dimethyl sulfoxide (DMSO, Sigma), and the
final concentration of DMSO in the KS liquid medium did
not exceed 0.1% of the total solution composition. Dilutions
of each compound were prepared in triplicate. The
final concentrations of the evaluated compounds ranged
from 100 to 0.05 μM. Plates were sealed with parafilm,
introduced into an anaerobic box with oxygen uptake
generators (GENbox anaer, France) for anaerobiosis.
The determination of results was performed visually after
The dependence of log(1/IC50) on compound lipophili-
city expressed by log k (Kos et al. 2015a) is shown in
Fig. 1a. After exclusion of three derivatives: 4-OCH3 (2c),
which precipitated from testing solution due to limited

Med Chem Res
Scheme 1 Synthesis of ring-
substituted 8-hydroxyquinoline-
2-carboxanilides 1–8c: Reagents
and conditions: a PCl3,
chlorobenzene, microwave-
assisted synthesis (Kos et al.
2015a)
compounds, six derivatives belonged to the set of the
above-mentioned most active compounds, the antibacterial
activity of which practically did not change with increasing
compound lipophilicity, indicating that this position of
substitution is favorable for significant antimicrobial effect.
The dependence of log(1/IC50) on the Hammett’s σ
constants of the R substituent is shown in Fig. 1b. Except
for derivatives with R = 4-OCH3 (2c) and 4-CH3 (3c) as
well as derivatives with F, Cl, and Br substituents in posi-
tions C’(2) and C’(4), i.e., 4a, 4c, 5a, 5c, 6a, and 6c, for the
remaining 14 compounds quasi-parabolic dependence of
log(1/IC50) on σ constants was estimated. However, it could
be mentioned that within a narrow range of σ from 0.06 to
0.22/0.23, the activity of C’(4) halogen-substituted com-
pounds decreased more sharply with increasing σ values
than that of C’(2)-substituted ones.
Similar trends as for the dependence of log(1/IC50) on
lipophilicity or on Hammett’s σ constants can be found also
for the dependences of the activity expressed as MIC or
MBC values on both parameters; therefore, these depen-
dences are not illustrated.
Summarizing, it can be concluded that generally for high
antibacterial activity against D. piger, halogen substituent in
the C’(3) position is favorable, whereby the highest anti-
bacterial activity was exhibited by derivatives with R =
3-CF3 and 4-CF3, i.e., substituents that are known to pro-
mote electrostatic interactions with targets and improve the
cellular membrane permeability of small molecules but also
compounds with low lipophilicity (2-CH3, 3-CH3, 2-OCH3,
3-OCH3).
Fig. 1 Dependence of antibacterial activity against Desulfovibrio
piger Vib-7 expressed as log(1/IC50) [M] of tested compounds on
lipophilicity expressed as log k (a) and on Hammett’s σ constants of R
substituent (b). (Compounds not included in individual SAR discus-
sions are marked by empty symbol.)
The estimated MIC values for D. piger (Table 1) are
comparable with those estimated for the antimycobacterial
activity of the tested compounds against Mycobacterium
tuberculosis H37Ra ATCC 25177, M. avium complex
CIT19/06 (clinical isolate) and M. avium subsp. para-
tuberculosis CIT03 (clinical isolate) (Kos et al. 2015a). It
was found that with the exception of compounds with R =
4-OCH3 (2c), 4-Cl (5c), 4-Br (6c), neither lipophilicity nor
electronic properties of the R substituent nor the position of
substitution exhibited any significant effect on the anti-
tubercular activity against M. tuberculosis, and the 2-, 3- and
4-CF3 (7a–c)-substituted derivatives belonged to the most
active compounds with MIC = 24 µM. There were no any
significant differences between antimycobacterial activities
against M. tuberculosis and M. avium subsp. para-
tuberculosis. On the other hand, C’(2) and especially C’(3)-
aqueous solubility, and 2-F (4a) and 3-NO2 (8b), showing
lower activity than expected, the compounds can be divided
into two groups. The antibacterial activity of nine deriva-
tives with R = 2-CH3 (3a), 2-OCH3 (2a), 3-OCH3 (2a), 3-F
(4b), 3-CH3 (3b), 3-Cl (5b), 3-Br (6b), 3-CF3 (7b), and 4-
CF3 (7c) expressed by IC50 value was comparable with that
of unsubstituted derivative 1 (R = H; IC50 = 12 µM) and
varied in the range from 10 µM (3-CF3 and 4-CF3, 3-CH3)
to 20 µM (3-F and 3-Cl), while the antibacterial activity of
other 12 tested (C’(2), C’(4)-substituted derivatives and (1)
compounds decreased linearly with increasing compound
lipophilicity from log k = 0.6944 (2-CH3, 3a; IC50 = 15
µM) to log k = 1.2347 (4-Br, 6c; IC50 = 225 µM) (r =
−0.9477, n = 12). Thus, from seven C’(3)-substituted

Med Chem Res
substituted derivatives expressed higher antimycobacterial
activity against M. avium complex than C’(4)-substituted
ones, and antimycobacterial activity slightly increased with
MIC values in the range from 0.22 to 0.35 μM against
D. piger Vib-7 and in the range from 0.27 to 8.52 μM
against Desulfomicrobium sp. Rod-9, while the MIC values
of ciprofloxacin were 41.2 μM and 39.3 μM, respectively.
Lipophilicity was recognized as a significant parameter
affecting biological activities, and higher activity for both
SRB was observed rather with electron-withdrawing R2
substituent and less lipophilic (isopropyl or benzyl) R3
substituent, and it was supposed that these derivatives
interact with enzymatic systems of the bacteria affecting
vital cell functions (Kushkevych 2015a, b; Kushkevych
et al. 2015a, b; Kushkevych et al. 2016). This is in agree-
ment with the presented results concerning the anti-
bacterial activity of ring-substituted 8-hydroxyquinoline-2-
carboxanilides against D. piger Vib-7. Thus, these results
confirmed that the investigated compounds showed high
efficiency not only against the aerobic microorganisms, but
also against the anaerobic microorganism.
increasing lipophilicity (log
k values) and electron-
withdrawing effect of R substituents; the C’(2)-substituted
compounds with log k > 0.8 and Hammett’s σ constants of R
substituents > 0.1 and C’(4)-substituted compounds with log
k < 0.8 were found to be completely ineffective. However,
the activity of compounds with potency against all three
strains was achieved by the substitution of the C’(3) position
of aniline. The significant bacterial/antimycobacterial
activity of the studied compounds bearing an 8-hydroxy-
quinoline fragment and an amide moiety in their molecule is
caused by the fact that these function groups are able to
interact with a number of enzymes/receptors via hydrogen
bonds and in this manner to affect the biological response
(Pattabiraman and Bode 2011; Lavecchia and Di Giovanni
2013; Zumla et al. 2013). The significant contribution of the
hydroxyl moiety in C(8) of quinoline to the anti-
mycobacterial activity was reported by Gonec et al. (2012),
who observed that its absence in quinoline-2-carboxanilides
resulted in a decrease of antimycobacterial effect, while
strengthening of antimycobacterial potency due to the pre-
sence of the hydroxyl moiety was observed with 1-hydroxy-
naphthalene-2-carboxanilides (Gonec et al. 2013) and 6-
hydroxy-naphthalene-2-carboxanilides (Kos et al. 2015b)
as compared to naphthalene-2-carboxanilides (Gonec et al.
2012).
Ring-substituted 8-hydroxyquinoline-2-carboxanilides
were previously tested also as photosystem II (PS II)
inhibitors (Jampilek et al 2016). The inhibition of photo-
synthetic electron transport (PET) in spinach chloroplasts
by these compounds significantly depended on the position
of substitution, and the inhibitory activity of C’(3)-sub-
stituted compounds was by one or two orders higher
than that of C’(2) and C’(4)-substituted derivatives. For the
most active compounds, the following IC50 values were
observed: 2.7 µM (3-CH3, 3b), 2.3 µM (3-F, 4b), 3.6 µM
(3-Cl, 5b), and 3.4 µM (3-Br, 6b). However, it could be
mentioned that the dependence of the PET-inhibiting
activity on the lipophilicity of the compounds expressed
by log k was quasi-parabolic for C’(3)-substituted deriva-
tives, while for C’(2) ones a slight increase and for
C’(4) derivatives a sharp decrease of the activity were
observed with increasing lipophilicity. Consequently,
it could be assumed that for targeting the site of action
in the photosynthetic apparatus suggested on the acceptor
side of photosystem II between P680 and plastoqui-
none QB substitution in the C’(3) position is the most
favorable.
Conclusion
Primary in vitro screening of a prepared series of ring-
substituted 8-hydroxyquinoline-2-carboxanilides was per-
formed against Desulfovibrio piger Vib-7. The most
effective compounds with MIC/MBC values in the range
of 17–23 µM/20–23 µM, respectively, were as follows:
8-hydroxy-N-(3-trifluoromethylphenyl)- (7b), 8-hydroxy-N-
(3-methoxyphenyl)- (2b) 8-hydroxy-N-(3-methylphenyl)-
(3b), and 8-hydroxy-N-(4-trifluoromethylphenyl)quinoline-
2-carboxamide (7c). Their activity was twofold higher
than that of ciprofloxacin. The antibacterial efficacy of the
most active C’(3)-substituted compounds practically did
not change with increasing compound lipophilicity, indi-
cating that this position of substitution is favorable for
significant antimicrobial effect, while the antibacterial
activity of most of C’(2) and C’(4)-substituted derivatives
decreased linearly with increasing compound lipophilicity.
In addition, the dependence of activity on electronic Ham-
mett’s σ parameter of the substituent R was quasi-parabolic
for the most effective C’(3)-substituted compounds. The
most potent compounds did not express any significant
cytotoxic effect on THP-1 cells up to the tested con-
centration of 30 µM.
Acknowledgements This study was supported by CZ.1.07/2.3.00/
30.0053, APVV-0516-12, IGA VFU Brno 318/2017/FaF, and also by
SANOFI-AVENTIS Pharma Slovakia, s.r.o.
Compliance with ethical standards
Previously tested six 2-(phenylcarbamoyl)phenyl N-
[(benzyloxy)carbonyl] alkanoates and three 2-hydroxy-N-
[(2 S)-1-oxo-1-(phenylamino)alkan-2-yl]benzamides showed
Conflict of interest The authors declare that they have no competing
interests.

Med Chem Res
Kaplan GG (2015) The global burden of IBD: from 2015 to 2025. Nat
Rev Gastroenterol Hepatol 12:720–727
References
Kos J, Zadrazilova I, Nevin E, Soral M, Gonec T, Kollar P, Oravec M,
Coffey A, O’Mahony J, Liptaj T, Kralova K, Jampilek J (2015a)
Ring-substituted 8-hydroxyquinoline-2-carboxanilides as poten-
tial antimycobacterial agents. Bioorg Med Chem 23:4188–4196
Kos J, Nevin E, Soral M, Kushkevych I, Gonec T, Bobal P, Kollar P,
Coffey A, O’Mahony J, Liptaj T, Kralova K, Jampilek J (2015b)
Synthesis and antimycobacterial properties of ring-substituted 6-
hydroxynaphthalene-2-carboxanilides. Bioorg Med Chem
23:2035–2043
Kushkevych I, Moroz OM (2012) Growth of various strains of sulfate-
reducing bacteria of human large intestine. Stud Biol 6:115–124
Kushkevych I (2013) Identification of sulfate-reducing bacteria strains
of human large intestine. Stud Biol 7:115–124
Kushkevych I (2014) Etiological role of sulfate-reducing bacteria in
the development of inflammatory bowel diseases and ulcerative
colitis. Am J Infect Dis Microbiol 2:63–73
Kushkevych I, Bartos M, Bartosova L (2014) Sequence analysis of the
16S rRNA gene of sulfate-reducing bacteria isolated from human
intestine. Int J Curr Microbiol Appl Sci 3:239–248
Barton LL, Hamilton WA (2010) Sulphate-reducing bacteria. Envir-
onmental and engineered systems. Cambridge University Press,
Cambridge
Cesar da Silva B, Lyra AC, Rocha R, Santana GO (2014) Epide-
miology, demographic characteristics and prognostic predictors
of ulcerative colitis. World J Gastroenterol 20:9458–9467
Cieslik W, Musiol R, Nycz J, Jampilek J, Vejsova M, Wolff M,
Machura B, Polanski J (2012) Contribution to investigation of
antimicrobial activity of styrylquinolines. Bioorg Med Chem
20:6960–6968
Cieslik W, Spaczynska E, Malarz K, Tabak D, Nevin E, O’Mahony J,
Coffey A, Mrozek-Wilczkiewicz A, Jampilek J, Musiol R (2015)
Investigation of the antimycobacterial activity of 8-
hydroxyquinoline. Med Chem 11:771–779
Clinical and Laboratory Standards Institute (CLSI) (2012). Methods
for antimicrobial susceptibility testing of anaerobic bacteria;
Approved standard, 8th edn. CLSI Document M11-A8. CLSI,
Wayne
Clinical and Laboratory Standards Institute (CLSI) (2014). perfor-
mance standards for antimicrobial susceptibility testing, 24th
Informational Supplement M100-S24. CLSI, Wayne
Cummings JH, MacFarlane GT, MacFarlane S (2003) Intestinal bac-
teria and ulcerative colitis. Curr Issues Intest Microbiol 4:9–20
Darby CM, Nathan CF (2010) Killing of non-replicating Myco-
bacterium tuberculosis by 8-hydroxyquinoline. J Antimicrob
Chemother 65:1424–1427
Feuerstein JD, Cheifetz AS (2014) Ulcerative colitis: Epidemiology,
diagnosis, and management. Mayo Clinic Proc 89:1553–1563
Finegold SM, Molitoris D, Vaaisanen ML (2009) Study of the in vitro
activities of rifaximin and comparator agents against 536 anae-
robic intestinal bacteria from the perspective of potential utility in
pathology involving bowel flora. Antimicrob Agents Chemother
53:281–286
Kushkevych I (2015a) Kinetic properties of pyruvate ferredoxin oxi-
doreductase of intestinal sulfate-reducing bacteria Desulfovibrio
piger Vib-7 and Desulfomicrobium sp. Rod-9. Polish J Microbiol
64:107–114
Kushkevych I (2015b) Activity and kinetic properties of phospho-
transacetylase from intestinal sulfate-reducing bacteria. Acta
Bioch Pol 62:1037–108
Kushkevych I, Fafula R, Parak T, Bartos M (2015a) Activity of Na
+/K+-activated Mg2+-dependent ATP hydrolase in the cell-free
extracts of the sulfate-reducing bacteria Desulfovibrio piger Vib-7
and Desulfomicrobium sp. Rod-9. Acta Vet Brno 84:3–12
Kushkevych I, Kollar P, Ferreira AL, Palma D, Duarte A, Lopes MM,
Bartos M, Pauk K, Imramovsky A, Jampilek J (2016) Anti-
microbial effect of salicylamide derivatives against intestinal
sulfate-reducing bacteria. J Appl Biomed 14:125–130
Garud S, Peppercorn MA (2009) Ulcerative colitis: Current treatment
strategies and future prospects. Therap Adv Gastroenterol
2:99–108
Gibson GR, Cummings JH, MacFarlane GT (1991) Growth and
activities of sulphate-reducing bacteria in gut contents of health
subjects and patients with ulcerative colitis. FEMS Microbiol
Ecol 86:103–112
Gibson GR, MacFarlane S, MacFarlane GT (1993) Metabolic inter-
actions involving sulphate-reducing and methanogenic bacteria in
the human large intestine. FEMS Microbiol Ecol 12:117–125
Gonec T, Bobal P, Sujan J, Pesko M, Guo J, Kralova K, Pavlacka L,
Vesely L, Kreckova E, Kos J, Coffey A, Kollar P, Imramovsky
A, Placek L, Jampilek J (2012) Investigating the spectrum of
biological activity of substituted quinoline-2-caboxamides and
their isosteres. Molecules 17:613–644
Gonec T, Kos J, Zadrazilova I, Pesko M, Keltosova S, Tengler J,
Bobal P, Kollar P, Cizek A, Kralova K, Jampilek J (2013)
Antimycobacterial and herbicidal activity of ring-substituted 1-
hydroxynaphthalene-2-carboxanilides. Bioorg Med Chem
21:6531–6541
Kushkevych I, Kollar P, Suchy P, Parak T, Pauk K, Imramovsky A
(2015b) Activity of selected salicylamides against intestinal
sulfate-reducing bacteria. Neuroendocrinol Lett 36:106–113
Lavecchia A, Di Giovanni C (2013) Virtual screening strategies in
drug discovery: A critical review. Curr Med Chem 20:2839–2860
Loubinoux J, Valente FMA, Pereira IAC (2002) Reclassification of the
only species of the genus Desulfomonas, Desulfomonas pigra, as
Desulfovibrio piger comb. nov. Int J Syst Evol Microbiol
52:1305–1308
Lozniewski A, Labia R, Haristoy X, Mory F (2001) Antimicrobial
susceptibilities of clinical Desulfovibrio isolates. Antimicrob
Agents Chemother 45:2933–2935
Mrozek-Wilczkiewicz A, Kalinowski D, Musiol R, Finster J, Szurko
A, Serafin K, Knas M, Kamalapuram SK, Kovacevic Z, Jampilek
J, Ratuszna A, Rzeszowska-Wolny J, Richardson DR, Polanski J
(2010) Investigating anti-proliferative activity of styr-
ylazanaphthalenes and azanaphthalenediones. Bioorg Med Chem
18:2664–2671
Musiol R, Jampilek J, Buchta V, Niedbala H, Podeszwa B, Palka A,
Majerz-Maniecka K, Oleksyn B, Polanski J (2006) Antifungal
properties of new series of quinoline derivatives. Bioorg Med
Chem 14:3592–3598
Musiol R, Jampilek J, Kralova K, Richardson DR, Kalinowski D,
Podeszwa B, Finster J, Niedbala H, Palka A, Polanski J (2007)
Investigating biological activity spectrum for novel quinoline
analogues. Bioorg Med Chem 15:1280–1288
Holt JG, Krieg NR, Sneath PH (1994) Bergey’s manual of determi-
native bacteriology, 9th edn. Williams & Wilkins, Philadelphia,
PA
Jampilek J, Dolezal M, Kunes J, Buchta V, Silva L, Kralova K (2005)
Quinaldine derivatives: Preparation and biological activity. Med
Chem 1:591–599
Jampilek J, Kralova K, Pesko M, Kos J (2016) Ring-Substituted 8-
hydroxyquinoline-2-carboxanilides as photosystem II inhibitors.
Bioorg Med Chem Lett 26:3862–3865
Musiol R, Tabak D, Niedbala H, Podeszwa B, Jampilek J, Kralova K,
Dohnal J, Finster J, Mencel A, Polanski J (2008) Investigating
biological activity spectrum for novel quinoline analogues 2:

Med Chem Res
Hydroxyquinolinecarboxamides with photosynthesis inhibiting
Rowan FE, Docherty NG, Coffey JC, O’Connell PR (2009) Sulphate-
reducing bacteria and hydrogen sulphide in the aetiology of
ulcerative colitis. Br J Surg 96:151–158
Wegmann U, Nueno-Palop C, Mayer MJ, Crost E, Narbad A (2017)
Complete genome sequence of Desulfovibrio piger FI11049.
Genome Announc 5:e01528–16
activity. Bioorg Med Chem 16:4490–4499
Musiol R, Jampilek J, Nycz JE, Pesko M, Carroll J, Kralova K,
Vejsova M, O’Mahony J, Coffey A, Mrozek A, Polanski J (2010)
Investigating the activity spectrum for ring-substituted 8-hydro-
xyquinolines. Molecules 15:288–304
Nakao K, Tanaka K, Ichiishi S, Mikamo H, Shibata T, Watanabe K
(2009) Susceptibilities of 23 Desulfovibrio isolates from humans.
Antimicrob Agents Chemother 53:5308–5311
Zinkevich V, Beech IB (2000) Screening of sulfate-reducing bacteria
in colonoscopy samples from healthy and colitic human gut
mucosa. FEMS Microbiol Ecol 34:147–155
Pattabiraman VR, Bode JW (2011) Rethinking amide bond synthesis.
Nature 480:471–479
Pitcher MC, Cummings JH (1996) Hydrogen sulphide: A bacterial
toxin in ulcerative colitis? Gut 39:1–4
Zumla A, Nahid P, Cole ST (2013) Advances in the development of
new tuberculosis drugs and treatment regimens. Nat Rev Drug
Discov 12:388–404