Investigating biological activity spectrum for novel styrylquinazoline analogues

Article abstract of DOI:10.3390/molecules14104246

In this study, series of ring-substituted 2-styrylquinazolin-4(3H)-one and 4-chloro-2-styrylquinazoline derivatives were prepared. The syntheses of the discussed compounds are presented. The compounds were analyzed by RP-HPLC to determine lipophilicity. They were tested for their inhibitory activity on photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Primary in vitro screening of the synthesized compounds was also performed against four mycobacterial strains and against eight fungal strains. Several compounds showed biological activity comparable with or higher than that of the standard isoniazid. It was found that the electronic properties of the R substituent, and not the total lipophilicity of the compound, were decisive for the photosynthesis-inhibiting activity of tested compounds.

Full text of DOI:10.3390/molecules14104246

Molecules 2009, 14, 4246-4265; doi:10.3390/molecules14104246
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Investigating Biological Activity Spectrum for Novel
Styrylquinazoline Analogues
Josef Jampilek 1,2,*, Robert Musiol 3, Jacek Finster 3, Matus Pesko 4, James Carroll 5,
Katarina Kralova 6, Marcela Vejsova 7, Jim O'Mahony 5, Aidan Coffey 5, Jiri Dohnal 1,2 and
Jaroslaw Polanski 3
1
Zentiva k.s., U kabelovny 130, 102 37 Prague 10, Czech Republic;
E-Mail: jiri.dohnal@zentiva.cz (J.D.)
2
Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical
Sciences, Palackeho 1-3, 612 42 Brno, Czech Republic
3
Institute of Chemistry, University of Silesia, Szkolna 9, 40007 Katowice, Poland;
E-Mails: robert.musiol@us.edu.pl (R.M.); jfinster@us.edu.pl (J.F.); polanski@us.edu.pl (J.P.)
4
Department of Ecosozology and Physiotactics, Faculty of Natural Sciences, Comenius University,
Mlynska dolina Ch-2, 84215 Bratislava, Slovakia; E-Mail: matus.pesko@gmail.com (M.P.)
5
Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland;
E-Mails: james.carroll@cit.ie (J.C.); jim.omahony@cit.ie (J.M.); aidan.coffey@cit.ie (A.C.)
6
Institute of Chemistry, Faculty of Natural Sciences, Comenius University, Mlynska dolina Ch-2,
84215 Bratislava, Slovakia; E-Mail: kralova@fns.uniba.sk (K.K.)
7
Department of Biological and Medical Sciences, Faculty of Pharmacy in Hradec Kralove, Charles
University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic;
E-Mail: marcela.vejsova@faf.cuni.cz (M.V.)
*
Author to whom correspondence should be addressed; E-Mail: josef.jampilek@zentiva.cz;
Tel.: +420267243695; Fax: +420272701331.
Received: 21 September 2009; in revised form: 13 October 2009 / Accepted: 21 October 2009 /
Published: 23 October 2009
Abstract: In this study, series of ring-substituted 2-styrylquinazolin-4(3H)-one and
4-chloro-2-styrylquinazoline derivatives were prepared. The syntheses of the discussed
compounds are presented. The compounds were analyzed by RP-HPLC to determine
lipophilicity. They were tested for their inhibitory activity on photosynthetic electron
transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Primary in vitro screening
of the synthesized compounds was also performed against four mycobacterial strains and

Molecules 2009, 14
against eight fungal strains. Several compounds showed biological activity comparable
4247
with or higher than that of the standard isoniazid. It was found that the electronic
properties of the R substituent, and not the total lipophilicity of the compound, were
decisive for the photosynthesis-inhibiting activity of tested compounds.
Keywords: styrylquinazolinone and styrylquinazoline derivatives; lipophilicity; PET
inhibition; spinach chloroplasts; in vitro antimycobacterial activity; in vitro antifungal
activity; structure-activity relationships
1. Introduction
A quinoline moiety is present in many classes of biologically-active compounds. A number of them
have been clinically used as antifungal, antibacterial and antiprotozoic drugs [1,2], as well as
antituberculotic agents [3-5]. Some quinoline-based compounds have also shown antineoplastic,
antiasthmatic and antiplatelet activity [6-11]. A series of compounds derived from 8-hydroxyquinoline
and styrylquinoline derivatives were recently synthesized as potential HIV-1 integrase inhibitors
[12-15]. Our previous study dealing with 8-hydroxyquinoline and styrylquinoline derivatives showed
that they could also possess strong antifungal activity [16,17]. According to recently reported results,
some new hydroxyquinoline derivatives also possess interesting herbicidal activities
[16,18-20]. In addition, some of the investigated quinoline derivatives also showed antineoplastic
activity [18,21].
Over 50% of commercially available herbicides act by reversibly binding to photosystem II (PS II),
a membrane-protein complex in the thylakoid membranes which catalyses the oxidation of water and
the reduction of plastoquinone [22] and thereby inhibit photosynthesis [23-25]. Some organic
compounds, e.g. substituted benzanilides [26] or substituted anilides of 2,6-disubstituted
pyridine-4-thiocarboxamides [27] or pyrazine-2-carboxylic acids [28,29] were found to interact with
tyrosine radicals TyrZ and TyrD which are situated in D1 and D2 proteins on the donor side of PS II.
Due to this interaction interruption of the photosynthetic electron transport occurred.
Tuberculosis (TB) is a worldwide pandemic. About 1/3 of the world's population is infected with
Mycobacterium tuberculosis, and almost two million people die every year as a result. A large number
of infected people are carriers of the latent form, which creates a potentially dangerous future source
of the illness. The HIV pandemic has also led to the rapid growth of the TB epidemic, and increased
the likelihood of people dying of TB. Another factor contributing to the rise in TB infections, and
consequently to the increased number of deaths, is the appearance of multiple drug-resistance (MDR),
i.e., rise of multidrug-resistant TB (MDR-TB) [30,31].
The Mycobacterium genus is composed of the M. tuberculosis complex and other species known as
nontuberculous mycobacteria (NTM, or MOTT – mycobacteria other than tuberculosis). In recent
decades, the decrease in the prevalence of tuberculosis in developed countries has resulted in an
increase in the proportion of diseases caused by NTM [32]. Among these species, the M. avium
complex (MAC) has emerged as a major human pathogen, being a common cause of disseminated
disease and death in patients with HIV/AIDS [33].

Molecules 2009, 14
4248
Chronic pulmonary disease is the most common clinical manifestation among the diseases caused
by NTM, and the most common pathogens are the species belonging to the MAC, followed by
M. kansasii. The clinical characteristics of NTM-related pulmonary disease are, in many cases,
extremely similar to those of tuberculosis. Other clinical manifestations are caused principally by
M. fortuitum, M. smegmatis and M. abscessus due to peritoneal infection as a result of catheterization
or postsurgical infections [34]. The above mentioned non-tuberculous strains are sometimes resistant
to commonly used drugs (isoniazid, rifampicin, pyrazinamide and ethambutol) and other
antituberculous drugs [30]. Therefore, systematic development of new effective compounds is
necessary. Similarly, there is also an urgent need for discovery of new drugs with novel modes of
action for the treatment of systemic mycoses. This is due to the rapid growth of the
immunocompromised patient population and development of resistance to current azole therapies, and
the high toxicity of polyenes [35]. It should be stressed that hydroxyquinolines and their derivatives
were introduced as antifungal or antimycobacterial agents in clinical practice and novel compounds of
this type are still being investigated [3-5,36,37].
This is a follow-up paper to our previous articles [12-21] dealing with synthesis and biological
activities of ring-substituted quinazolinone derivatives. In the context of our previously-described
azanaphtalenes, new modifications of quinoline moiety that can trigger interesting biological activity
were investigated.
Primary in vitro screening of the synthesized compounds was performed against four mycobacterial
strains and against eight fungal strains. The compounds were also tested for their photosynthesis-
inhibiting activity (the inhibition of photosynthetic electron transport) in spinach chloroplasts
(Spinacia oleracea L.). Lipophilicity (log k) of the compounds was determined using RP-HPLC.
Relationships among the structure and in vitro antimicrobial activities or/and inhibitory activity
related to inhibition of photosynthetic electron transport (PET) in spinach chloroplasts of the new
compounds are discussed.
2. Results and Discussion
2.1. Chemistry
All the studied compounds were prepared according to Scheme 1. Microwave-assisted synthesis
facilitated the preparation of quinazoline-related structures. 2-Methyl-4H-benzo[d][1,3]oxazin-4-one
was synthesized from anthranilic acid and acetic anhydride. A further reaction with ammonia or
hydroxylamine afforded 2-methylquinazolin-4(3H)-one (1) or 3-(2-hydroxyethyl)-2-methylquinazolin-
4(3H)-one (2). 2-Styrylquinazolin-4(3H)-ones 3a-k were obtained from appropriate aldehydes using
neat microwave-assisted synthesis [38]. Further chlorination/dehydratation with POCl3 yielded
4-chloro-2-styrylquinazoline derivatives 4a-e. Styrylquinazolines can exist as E- or Z-isomers
according to the orientation of the ethylene linker. This can greatly affect their biological activity
i.e., behaviour at the site of action and complexation mechanism(s). Thus we have studied the
isomerism of all the obtained compounds with NMR techniques and crystallography, as formerly
described for similar structures [39,40]. Fortunately this feature can be easily determined by
examination of the coupling constants of both vinyl protons in the spectra. These are much higher in

Molecules 2009, 14
4249
the case of E-isomers (J > 16 Hz) compared to Z-isomers (J < 12 Hz) [39]. All styrylquinazolines were
found to be pure E-isomers, which is in good agreement with previous results [13,17,18,39,40].
Scheme 1. Synthetic pathway and general formula of prepared quinazolinone derivatives:
O
O
O
O
OH
NH2
O
NH
NH
a
b
d
N
N
N
R
1
3a-k
c
e
Cl
O
N
OH
N
N
N
R
2
4a-e
Reagents and Conditions: a) Ac2O, MW; b) NH3aq, MW; c) NH2C2H4OH, MW; d) aldehyde, MW;
e) POCl3.
2.2. Lipophilicity
Many low molecular weight drugs cross biological membranes through passive transport, which
strongly depends on their lipophilicity. Lipophilicity is a property that has a major effect on
absorption, distribution, metabolism, excretion, and toxicity (ADME/Tox) properties, as well as
pharmacological activity. Lipophilicity has been studied and applied as an important drug property for
decades [41].
This thermodynamic parameter describes the partitioning of a compound between aqueous and
organic phases and is characterized by the partition (log P) coefficient [42,43]. With new
computerized methods of log P calculation, the possibility of predicting hydrophobicity in large
libraries of compounds came into being. Lipophilicity computing software can usually calculate log P
and Clog P. The software calculates log P values as lipophilicity contributions/increments of
individual atoms, fragments and the pairs of interacting fragments in the chemical structure, i.e.,
increments of carbon and hetero atoms, aromatic systems and functional groups. The software
calculates lipophilicity contributions according to different internal databases/libraries, so the
calculated lipophilicity values are dependent on the software used, and the values for individual
compounds may be different. This fact, as well as various ionic/zwitterionic forms and intramolecular
interactions, may cause differences between calculated and experimentally determined lipophilicities.
Classical methods for determination of these partition constants are time consuming and not always
adequately reliable. It was recognised some time ago that the retention of a compound in reversed-
phase liquid chromatography is governed by its lipophilicity, and thus shows correlation with the
octanol–water partition coefficient [44]. Reversed phase high performance liquid chromatography
(RP-HPLC) provides an excellent platform for computer controlled automated measurements with
computerised data acquisition for a large number of investigated compounds. Other advantages in the
use of HPLC retention data for lipophilicity determination are the absence of need for concentration

Molecules 2009, 14
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determination and method validation, simultaneous separation of small impurities from the main
component, sufficiency of small amounts of material for measurements and possibility of their full
automation. Therefore the investigation of the true potential of this method is of great importance [45].
The effect of stationary and mobile phase selection has been published by van der Waterbeemd et
al. [43] and more recently by Claessens et al. [46]. RP-HPLC methods have become popular and
widely used for lipophilicity measurement [47]. A general procedure is the measurement of the
directly accessible retention time under isocratic conditions with varying amounts of methanol as an
organic modifier in the mobile phase using end-capped non-polar C18 stationary RP columns and
calculating the logarithm of capacity factors (log k). Log k is the logarithm of capacity factors in
chromatographic approaches, which is related to the partitioning of a compound between a mobile and
a (pseudo-)stationary phase. Log k is used as the lipophilicity index converted to log P scale [43,45-49].
Some groups have used a C18 chromatographic column with methanol-water mobile phases to
obtain log kw, i.e., the retention factor extrapolated to 0% organic modifier, as an alternative to log P
[50]. The log kw is obtained by performing several measurements with various ratios of water/organic
solvent. Nevertheless determination of log kw has some disadvantages in that it is time consuming due
to the various measurements that need to be undertaken before calculation of log kw [44]. The main
reason for the measurement is that it is more convenient to perform a systematic study of log k of
various heteroaromatic compounds using mobile phases containing around 50% methanol due to
various intramolecular interactions between heteroatoms and substituents [51-53]. Therefore this study
was performed using methanol/water (55:45) as the mobile phase. The conditions (non-buffered
mobile phase) were chosen with respect to conditions of biological evaluations, which are performed
mostly under neutral conditions (pH ~ 7). The lipophilicity data can be strongly influenced by
intramolecular interactions under the applied chromatographic conditions which were investigated in
the paper [54,55].
Lipophilicities (log P/Clog P) of all eighteen compounds 1-4e were calculated using two
commercially available programs (ChemDraw Ultra and ACD/LogP) and also measured by means of
the RP-HPLC determination of capacity factors k with subsequent calculation of log k. The procedure
was performed under isocratic conditions. Neither programme succeeded in resolving the differing
lipophilicity values of individual positional isomers inasmuch as the same log P/Clog P values were
calculated for 3b-d, 3g-i and 4b-d. The results are shown in Table 1 and illustrated in Figure 1.
The results obtained with respect to all compounds show that the experimentally-determined
lipophilicities (log k values) of all compounds are lower than those indicated by the calculated
log P/Clog P, as shown in Figure 1, indicating that experimentally-determined log k values correlate
relatively poorly with the calculated log P/Clog P. These facts are caused by both the above
mentioned limitation of the software programmes used and also possibly to intramolecular interactions
between heterocyclic nitrogens and substituents [19,54-59]. As expected, compound 3i showed the
highest lipophilicity, while compound 1 exhibited the lowest. Series 4a-e showed lower lipophilicity
(log k) than series 3a-e, contrary to all calculated log P/Clog P data. The higher lipophilicity of 3a-e
compared with 4a-e is caused by intramolecular interactions between N(3) and carbonyl oxygen in the
position 4. Similar interactions were described recently [19,55-59]. This hypothesis can be supported
by the fact that log k of 1 was lower than 2, although this is contrary to calculated log P/Clog P. When
the lipophilicity of both compounds was calculated with intramolecular interactions between

Molecules 2009, 14
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N(3)-H···O=C(4), the lipophilicity increased (Clog P (1): 1.343 and Clog P (2): 2.2306). Similar facts
may be observed at 3a-e and 4a-e, therefore the experimental log k data of 4a-e were slightly lower
than those log k of 3a-e.
Table 1. Comparison of the calculated lipophilicities (log P/Clog P) with the determined
log k values, electronic Hammett's parameters (σ) and bulk parameters MR (volume of
substituents) [60].
log P/Clog P
log P
Comp.
R
log k
σ [60]
MR [60]
ChemOffice
ACD/LogP
O
NH
1
2
0.1170
0.98 / 0.804
-0.36 ± 0.59
-1.23 ± 0.69
–
–
–
–
N
O
N
OH
N
0.7047 0.69 / 0.6149
O
NH
N
R
3a
3b
3c
3d
3e
3f
H
1.1148
1.1509
1.1837
1.1351
1.1982
1.5059
1.4830
1.5904
1.5927
0.8005
0.5510
3.21 / 2.997
3.09 / 2.916
3.09 / 2.916
3.09 / 2.916
2.96 / 3.005
3.77 / 3.710
4.04 / 3.860
4.04 / 3.860
4.04 / 3.860
2.96 / 2.350
2.37 ± 0.61
0.0
0.0
6.5
6.5
6.5
13.0
4.8
7.6
7.6
7.6
5.3
4.5
2-OCH3
3-OCH3
4-OCH3
2.35 ± 0.62 -0.390 [61]
2.35 ± 0.62 0.115
2.32 ± 0.62 -0.268
2.20 ± 0.62 -0.658
2,4-OCH3
3-Cl
2.96 ± 0.61
3.14 ± 0.64
3.14 ± 0.64
3.14 ± 0.64
1.79 ± 0.63
1.84 ± 0.63
0.373
–
3g
3h
3i
2-Br
3-Br
0.391
0.232
1.030
–
4-Br
3j
4-CHO
2,3,4-OH
3k
2.05 / 1.066
Cl
N
N
R
4a
4b
4c
4d
4e
H
1.1088 5.50 / 4.51522
1.1497 5.38 / 4.43422
1.1827 5.38 / 4.43422
1.1337 5.38 / 4.43422
1.1953 5.25 / 4.52322
4.47 ± 0.56
0.0
0.0
6.5
2-OCH3
3-OCH3
4-OCH3
2,4-OCH3
4.47 ± 0.57 -0.390 [61]
4.44 ± 0.57 0.115
6.5
4.41 ± 0.57 -0.268
4.30 ± 0.57 -0.658
6.5
13.0
The presence of phenolic and carbonyl moieties decreased the lipophilicity. Nevertheless, the
observation that the lipophilicity of compounds 3k and 3j was close to the lipophilicity of compound 2
was unexpected. Compound 3f showed less lipophilicity compared with 3h. On the basis of

Molecules 2009, 14
4252
comparison of the lipophilicity data log k of both Br-substituted isomers 3g-3i, it can be stated that
4-bromo derivative 3i possessed higher lipophilicity than the 3-bromo isomer 3h and the 2-bromo
isomer 3g. A diverse trend can be observed at methoxy moiety substituted compounds 3b-e and 4b-e.
Compounds 3e and 4e showed the highest lipophilicity, while compounds 3a and 4a possessed the
lowest lipophilicity within individual series of methoxy moiety substituted compounds, according to
log k data. Compounds 3a and 4a showed lower lipophilicity in comparison with the results calculated
by the software. If the lipophilicity data log k of three position isomers 3b-d, 4b-d are compared, it
can be stated that 3-methoxy derivative 3c/4c possessed higher lipophilicity than 2-methoxy derivative
3b/4b and 4-methoxy derivative 3d/4d showed the lowest lipophilicity.
Figure 1. Comparison of the log P/Clog P values computed using the two programs with
the calculated log k values. The discussed compounds 1-4e are ordered according to the
increase in log k values.
6.0
5.0
4.0
3.0
2.0
1.0
0.0
1
3k
2
3j
4a 3a 4d 3d 4b 3b 4c 3c 4e 3e 3g
3f 3h
3i
-1.0
-2.0
Compounds
log k log P[ChemOffice] Clog P[ChemOffice] log P [ACD/LogP]
Generally, based on the facts discussed above, it can be stated that intramolecular interactions,
especially within styrylquinazolinone derivatives, play a significant role in the lipophilicity of the
discussed compounds. It can be assumed that the determined log k data specify lipophilicity within the
individual series of compounds. Lipophilicity increased in the following order: 2,3,4-OH < 4-CHO <
H < 4-OCH3 < 2-OCH3 < 3-OCH3 < 2,4-OCH3 < 2-Br < 3-Cl < 3-Br < 4-Br.
2.3. Inhibition of photosynthetic electron transport (PET) in spinach chloroplasts
The evaluated quinazoline derivatives showed relatively low activity related to inhibition of
photosynthetic electron transport (PET) in spinach chloroplasts (Table 2). Compounds 4a and 4c
expressed the highest PET-inhibiting activity (IC50: 285 and 303 µmol/L, respectively). PET inhibition
by several compounds (1, 3a-c, 3g, 3j and 4b) could not be determined due to precipitation of the
compounds during the experiment and compound 3k interacted with the artificial electron acceptor
DCPIP (change of the colour). The PET-inhibiting activity was expressed by negative logarithm of

Molecules 2009, 14
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IC50 value (compound concentration in mol/L causing 50% inhibition of PET). Despite the relatively
low inhibitory activity of the studied compounds as well as the relative scarcity of compounds for
which PET-inhibiting activity could be determined, the correlations between log (1/IC50) and log k or
Hammett's parameters (σ) of the R substituent for both tested groups (3d-i, as well as 4a-d) were
performed. The σ values [60,61] mentioned in Table 1 were used for calculations; the σ value for
R: 2,4-OCH3 was calculated from the sum of corresponding σ values for R: 2-OCH3 and R: 4-OCH3.
Table 2. IC50 values related to PET inhibition in spinach chloroplasts in comparison with
3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) standard and in vitro antimycobacterial
activity MIC/IC90 of compounds 1-3i, 4a-4e in comparison with the standard, isoniazid
(INH).
MIC/IC90 [µg/mL]
PET inhibition
Comp.
IC50 [μmol/L]
M. smegmatis M. absessus M. kansasii M. avium complex
a
1
2
>300
>300
>300
>100
>100
>100
>100
>300
>100
>100
>100
>100
>100
>100
>100
>100
–
>300
>300
>300
>100
>100
>100
80
>300
>300
>300
>100
>100
>100
20
>300
>300
>300
>100
>100
>100
80
362
a
3a
a
a
3b
3c
3d
693
391
3e
3f
1034
>300
>100
>100
>100
>100
80
>300
>100
>100
>100
>100
60
>300
>100
>100
>100
>100
80
a
3g
3h
561
665
3i
4a
285
a
4b
4c
303
390
508
1.9
–
>100
>100
>100
–
60
>100
>100
>100
–
4d
>100
>100
–
4e
DCMU
INH
39
>100
<10
<10
a precipitation during the experiment or interaction with DCPIP.
The importance of electronic properties of the R substituent was for the inhibitory activity (IC50 in
mol/L) of compounds 3a-i unambiguously much more significant than the compound lipophilicity
(log k):
log (1/IC50) = 3.216 (± 0.048) – 0.218 (± 0.095) σ
r = 0.798, s = 0.106, F = 5.26, n = 5
(1)
(2)
log (1/IC50) = 3.545 (± 0.530) - 0.248 (± 0.374) log k
r = 0.358, s = 0.160, F = 0.44, n = 5

Molecules 2009, 14
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Similarly, the inhibitory activity (IC50 in mol/L) of compounds 4a-e depended predominantly on
the Hammett's constants (σ) of R substituents:
log (1/IC50) = 3.507 (± 0.020) + 0.324 (± 0.056) σ
r = 0.971, s = 0.033, F = 33.24, n = 4
(3)
(4)
log (1/IC50) = 5.272 (± 1.900) – 1.584 (± 1.644) log k
r = 0.563, s = 0.116, F = 0.93, n = 4
From Equations 1-4 it is evident that in both studied groups of compounds (3d-i and 4a-d) the
electronic properties of the R substituent were decisive for photosynthesis-inhibiting activity. For
estimation of the potential contribution of the compound lipophilicity to its biological activity, a larger
data set for both groups of compounds tested would be necessary.
2.4. In vitro antimycobacterial evaluation
Sixteen compounds 1-3i, 4a-4e were evaluated for their in vitro antimycobacterial activity against
four mycobacterial strains and the results are shown in Table 2. According to the results, it is evident
that the tested compounds were poorly soluble in the testing medium and therefore concentrations of
the compounds in the medium were not sufficient for determination of real antimycobacterial activity.
Due to this fact, it can be concluded that the majority of compounds evaluated did not show any
significant antimycobacterial activity. Only 2-[(E)-2-(2,4-dimethoxyphenyl)vinyl]quinazolin-4(3H)-
one (3e) and 4-chloro-2-[(E)-2-(2-methoxyphenyl)vinyl]quinazoline (4b) expressed an interesting
MIC especially against M. kansasii, M. avium complex and M. absessus. Both compounds were more
active than INH in case of M. absessus.
With the available data it is difficult to attempt to determine any structure-activity relationships,
although some observations can be made. The 4-chloroquinazoline nucleus (series 4) seems to be
more advantageous for higher antimycobacterial activity than the quinazolin-4(3H)-one scaffold
(series 3); e.g., unsubstituted 3a showed lower activity than 4a.
The benzylidene part of the molecule is also important for antimycobacterial activity. Bulk
parameters (the volume of substituents) MR [60] are also very important for activity. According to
Tables 1 and 2 it can be assumed that compounds with bulky substituents showed higher
antimycobacterial activity. Unsubstituted compounds 3a and chloro substituted 3f possessed less
activity than methoxy or bromo substituted compounds. The highest effect was shown by disubstituted
2,4-methoxy derivative 3e. The position of substituents on the benzylidene part of the molecule is
important especially for compounds within series 4; compare the activity of compounds 4b > 4c > 4d
> 4e.
2.5. In vitro antifungal susceptibility testing
All quinazoline derivatives 1-4e were tested for their in vitro antifungal activity against eight fungal
strains. The antifungal activity of all the compounds were in the range from >125 to >500 μmol/L and
therefore the activities are not presented in detail. According to these results, it can be concluded that
all the compounds are almost completely insoluble in aqueous solvents as they precipitated from the
testing medium. Generally, compounds 1 and 2 showed lower activity than most compounds 3 and 4.

Molecules 2009, 14
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The substitution of benzylidene part of the molecule by 3-OCH3 (3c, 4c) or 2,3,4-OH (3k) seems to
contribute to antifungal activity within both series of compounds.
3. Conclusions
Series of ring-substituted 2-styrylquinazolin-4(3H)-one and 4-chloro-2-styrylquinazoline
derivatives were prepared and characterized. All eighteen prepared quinazoline derivatives were
analyzed using a RP-HPLC method for lipophilicity measurement and their lipophilicity was
determined. The prepared compounds were tested for their antifungal and antimycobacterial activity
and for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach
chloroplasts (Spinacia oleracea L.). 2-[(E)-2-(2,4-Dimethoxyphenyl)vinyl]quinazolin-4(3H)-one (3e)
and 4-chloro-2-[(E)-2-(2-methoxyphenyl)vinyl]quinazoline (4b) exhibited the highest in vitro
antimycobacterial activity. 4-Chloro-2-[(E)-2-(3-methoxyphenyl)vinyl]quinazoline (4c) showed the
highest PET-inhibiting activity.
4. Experimental
4.1. General
All reagents were purchased from Aldrich. Kieselgel 60, 0.040–0.063 mm (Merck, Darmstadt,
Germany) was used for column chromatography. TLC experiments were performed on alumina-
backed silica gel 40 F254 plates (Merck, Darmstadt, Germany). The plates were illuminated under UV
(254 nm) and evaluated in iodine vapour. The melting points were determined on Boetius PHMK 05
(VEB Kombinat Nagema, Radebeul, Germany) and are uncorrected. The purity of the final
compounds was checked by the HPLC separation module Waters Alliance 2695 XE (Waters Corp.,
Milford, MA, U.S.A.). The detection wavelength 210 nm was chosen. The peaks in the chromatogram
of the solvent (blank) were deducted from the peaks in the chromatogram of the sample solution. The
purity of individual compounds was determined from the area peaks in the chromatogram of the
sample solution. UV spectra (λ, nm) were determined on a Waters Photodiode Array Detector 2996
(Waters Corp., Milford, MA, U.S.A.) in ca 6×10-4 mol methanolic solution and log ε (the logarithm of
molar absorption coefficient ε) was calculated for the absolute maximum λmax of individual target
compounds. Infrared spectra were recorded using KBr pellets on the FT-IR spectrometer Nicolet 6700
1
(Nicolet - Thermo Scientific, U.S.A.). All H-NMR spectra were recorded on a Bruker AM-500
(499.95 MHz for 1H) instrument (Bruker BioSpin Corp., Germany). Chemicals shifts are reported in
ppm (δ) to internal Si(CH3)4, when diffused easily exchangeable signals are omitted.
4.2. Synthesis
2-Methylquinazolin-4(3H)-one (1): Yield 77% of a white crystalline compound; mp 245-247 °C (lit.
1
mp 242-244 °C [62]); HPLC purity: 98.64%; UV (nm), λmax/log ε: 305.1/3.53; H-NMR [(CD3)2CO]
δ: 2.45 (s, 3H, CH3), 7.44 (t, 1H, Ar-H), 7.59 (d, J = 8.15 Hz, 1H, Ar-H), 7.76 (t, 1H, Ar-H), 8.13 (d,
J = 7.94 Hz, 1H, Ar-H), 11.00 (s, 1H, NH).

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3-(2-Hydroxyethyl)-2-methylquinazolin-4(3H)-one (2). Yield 52% of a white crystalline compound;
mp 154-156 °C; HPLC purity: 99.67%; UV (nm), λmax/log ε: 305.8/3.58; 1H-NMR (DMSO-d6) δ: 2.65
(s, 3H, CH3), 3.66 (q, 2H, CH2), 4.12 (t, 2H, CH2), 5.00 (t, 1H, OH), 7.46 (t, 1H, Ar-H), 7.57
(d, J = 8.14 Hz, 1H, Ar-H), 7.77 (t, 1H, Ar-H), 8.08 (d, J = 8.00 Hz, 1H, Ar-H).
4.2.1. General procedures of synthesis of Compounds 3a-k
A mixture of compound 1 (0.01 mol) and the appropriate aldehyde (0.02 mol) was mixed
thoroughly and irradiated in monomode cavity of microwave reactor using pulse sequence
(3×5 minutes with 30 sec. intervals) at 250 W. During irradiation, the temperature was controlled
between the range 150-180 °C. After the reaction, the mixture was cooled and washed with boiling
ether. The product was crystallized from acetic acid.
2-(E)-Styrylquinazolin-4(3H)-one (3a). [63] Yield 50% of a white crystalline compound;
mp 253-255 °C (lit. mp 252 °C [64]); HPLC purity: 97.95%; UV (nm), λmax/log ε: 321.3/3.53;
1H-NMR (DMSO-d6) δ: 7.00 (d, J = 16.23 Hz, 1H, C=C-H), 7.41 (t, 1H, Ar-H), 7.42-7.49 (m, 3H,
Ar-H), 7.65-7.68 (m, 3H, Ar-H), 7.80 (t, 1H, Ar-H), 7.95 (d, J = 16.16 Hz, 1H, C=C-H), 8.10 (d, 1H,
Ar-H), 12.35 (s, 1H, N-H).
2-[(E)-2-(2-Methoxyphenyl)vinyl]quinazolin-4(3H)-one (3b). [63] Yield 76% of a white crystalline
compound; mp 234-236 °C (lit. mp 234-236 °C [64]); HPLC purity: 94.04%; UV (nm), λmax/log ε:
343.4/3.62; 1H-NMR (DMSO-d6) δ: 3.90 (s, 3H, OCH3), 7.02 (t, 1H, Ar-H), 7.07 (d, J = 16.24 Hz, 1H,
C=C-H), 7.11 (d, 1H, Ar-H), 7.39 (t, 1H, Ar-H), 7.45 (t, 1H, Ar-H), 7.60 (d, 1H,
Ar-H), 7.67 (d, 1H, Ar-H), 7.79 (t, 1H, Ar-H), 8.09 (d, 1H, Ar-H), 8.15 (d, J = 16.12 Hz, 1H, C=C-H),
12.36 (s, 1H, N-H).
2-[(E)-2-(3-Methoxyphenyl)vinyl]quinazolin-4(3H)-one (3c). [63] Yield 68% of a white crystalline
1
compound; mp 239-241 °C; HPLC purity: 96.82%; UV (nm), λmax/log ε: 326.4/3.58; H-NMR
(DMSO-d6) δ: 3.81 (s, 3H, OCH3), 6.98 (d, 1H, Ar-H), 7.01 (d, J = 16.81 Hz, 1H, C=C-H), 7.22 (s,
1H, Ar-H), 7.23 (d, 1H, Ar-H), 7.37 (t, 1H, Ar-H), 7.47 (t, 1H, Ar-H), 7.66 (d, 1H, Ar-H), 7.80 (t, 1H,
Ar-H), 7.91 (d, J = 16.14 Hz, 1H, C=C-H), 8.10 (d, 1H, Ar-H), 12.31 (s, 1H, NH).
2-[(E)-2-(4-Methoxyphenyl)vinyl]quinazolin-4(3H)-one (3d). [63] Yield 33% of a white crystalline
compound; mp 280-281 °C (lit. mp 284-285 °C [64]); HPLC purity: 94.36%; UV (nm), λmax/log ε:
322.7/3.59; 1H-NMR (DMSO-d6) δ: 3.80 (s, 3H, OCH3), 6.84 (d, J = 16.23 Hz, 1H, C=C-H), 7.01 (d,
2H, Ar-H), 7.45 (t, 1H, Ar-H), 7.60 (d, 2H, Ar-H), 7.64 (d, 1H, Ar-H), 7.78 (t, 1H, Ar-H), 7.90
(d, J = 16.08 Hz, 1H, C=C-H), 8.08 (d, 1H, Ar-H), 12.25 (s, 1H, N-H).
2-[(E)-2-(2,4-Dimethoxyphenyl)vinyl]quinazolin-4(3H)-one (3e). [63] Yield 57% of a white
crystalline compound; mp 228-230 °C (lit. mp 228-230 °C [64]); HPLC purity: 96.27%; UV (nm),
1
λ
max/log ε: 350.1/3.67; H-NMR (DMSO-d6) δ: 3.82 (s, 3H, OCH3), 3.90 (s, 3H, OCH3), 6.63 (d, 1H,
Ar-H), 6.64 (s, 1H, Ar-H), 6.94 (d, J = 16.15 Hz, 1H, C=C-H), 7.43 (t, 1H, Ar-H), 7.53 (d, 1H, Ar-H),

Molecules 2009, 14
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7.64 (d, 1H, Ar-H), 7.77 (t, 1H, Ar-H), 8.07 (d, J = 15.21 Hz, 1H, C=C-H), 8.08 (d, 1H, Ar-H), 12.26
(s, 1H, N-H).
2-[(E)-2-(3-Chlorophenyl)vinyl]quinazolin-4(3H)-one (3f). [63] Yield 93% of a white crystalline
1
compound; mp 289 °C; HPLC purity: 96.51%; UV (nm), λmax/log ε: 326.4/3.59; H-NMR (CDCl3) δ:
6.93 (d, J = 16.41 Hz, 1H, C=C-H), 7.39 (d, 2H, Ar-H), 7.46-7.53 (m, 2H, Ar-H), 7.64 (s, 1H, Ar-H),
7.79 (d, J = 16 Hz, 1H, C=C-H), 7.77-7.83 (m, 2H, Ar-H), 8.33 (d, 1H, Ar-H), 10.64 (s, 1H, NH).
2-[(E)-2-(2-Bromophenyl)vinyl]quinazolin-4(3H)-one (3g). [63] Yield 71% of a white crystalline
1
compound; mp 279 °C; HPLC purity: 98.84%; UV (nm), λmax/log ε: 326.9/3.59; H-NMR (CDCl3) δ:
6.93 (d, J = 16.47 Hz, 1H, C=C-H), 7.40 (t, 1H, Ar-H), 7.50 (t, 1H, Ar-H), 7.67 (d,
J = 7.90 Hz, 1H, Ar-H), 7.74-7.82 (m, 4H, Ar-H), 8.12 (d, J = 16.45 Hz, 1H, C=C-H), 8.36 (d,
J = 7.88 Hz, 1H, Ar-H), 10.96 (s, 1H, NH).
2-[(E)-2-(3-Bromophenyl)vinyl]quinazolin-4(3H)-one (3h). [63] Yield 43% of a white crystalline
1
compound; mp 277-279 °C; HPLC purity: 97.34%; UV (nm), λmax/log ε: 326.4/3.58; H-NMR
(CDCl3) δ: 6.91 (d, J = 16.33 Hz, 1H, C=C-H), 7.33 (t, 1H, Ar-H), 7.50-7.56 (m, 2H, Ar-H), 7.55 (s,
1H, Ar-H), 7.73 (d, J = 16.49 Hz, 1H, C=C-H), 7.76-7.82 (m, 3H, Ar-H), 8.33 (d, 1H, Ar-H), 10.31 (s,
1H, NH).
2-[(E)-2-(4-Bromophenyl)vinyl]quinazolin-4(3H)-one (3i). [63] Yield 66% of a white crystalline
compound; mp 332 °C; HPLC purity: 97.64%; UV (nm), λmax/log ε: 326.7/3.58; 1H-NMR (DMSO-d6)
δ: 7.03 (d, 1H, C=C-H), 7.49 (t, 1H, Ar-H), 7.61 (d, 1H, Ar-H), 7.64 (d, 2H, Ar-H), 7.66 (d, 1H,
Ar-H), 7.68 (d, 1H, Ar-H), 7.81 (t, 1H, Ar-H), 7.91 (d, 1H, C=C-H), 8.11 (d, 1H, Ar-H), 12.36 (s, 1H,
N-H).
2-[(E)-2-(4-Carbaldehydephenyl)vinyl]quinazolin-4(3H)-one (3j). [63] Yield 35% of a white
1
crystalline compound; mp 218 °C; HPLC purity: 96.93%;. UV (nm), λmax/log ε: 337.9/3.69; H-NMR
(CDCl3) δ: 7.16 (d, J = 16.13 Hz, 1H, C=C-H), 7.50 (t, 1H, Ar-H), 7.69 (d, 2H, Ar-H), 7.82 (t, 1H,
Ar-H), 7.87 (d, 1H, Ar-H), 7.97 (d, 1H, Ar-H), 8.00 (d, J = 16.21 Hz, 1H, C=C-H), 8.11 (d, 2H, Ar-H),
9.95 (s, 1H, CHO), 10.02 (s, 1H, N-H).
2-[(E)-2-(2,3,4-Trihydroxyphenyl)vinyl]quinazolin-4(3H)-one (3k). [63] Yield 60% of a brown
crystalline compound; mp 300 °C (decomp.); HPLC purity: 97.67%; UV (nm), λmax/log ε: 365.0/3.65;
1H-NMR (DMSO-d6), δ: 6.39 (d, 1H, Ar-H), 6.83 (d, J = 15.98 Hz, 1H, C=C-H), 6.88 (d, 1H, Ar-H),
7.40 (t, 1H, Ar-H), 7.63 (d, 1H, Ar-H), 7.75 (t, 1H, Ar-H), 8.05 (d, 1H, Ar-H), 8.10 (d, J = 16.05 Hz,
1H, C=C-H), 8.57 (s, 1H, OH), 9.07 (s, 1H, OH), 9.68 (s, 1H, OH), 12.19 (s, 1H, NH).
4.2.2. General procedures of synthesis of Compounds 4a-e
A mixture of styrylquinazolinone derivatives 3 (0.01 mol), N,N-dimethylaniline (0.02 mol) and
phosphorus oxychloride (0.015 mol) in dry benzene (50 mL) was stirred and heated under reflux for

Molecules 2009, 14
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3 h. The reaction mixture was then cooled and filtered. The filtrate was diluted with benzene (30 mL)
and the solution washed with water (50 mL), twice with 20 % aqueous NaOH (50 mL) and finally
twice with water. After drying with MgSO4, the organic solvent was evaporated and the product
obtained was crystallized from heptane.
4-Chloro-2-(E)-styrylquinazoline (4a). [63] Yield 81% of an orange crystalline compound; mp
1
104 °C, (lit. mp 100-101 °C [65]); HPLC purity: 99.34%; UV (nm), λmax/log ε: 314.9/3.67; H-NMR
(DMSO-d6) δ: 7.34 (d, J = 15.91 Hz, 1H, C=C-H), 7.41 (t, 1H, Ar-H), 7.47 (t, 2H, Ar-H), 7.77-7.80
(m, 3H, Ar-H), 8.02 (d, 1H, Ar-H), 8.06 (t, 1H, Ar-H), 8.12 (d, J = 16.01 Hz, 1H, C=C-H), 8.26 (d,
1H,Ar-H).
4-Chloro-2-[(E)-2-(2-methoxyphenyl)vinyl]quinazoline (4b). [63] Yield 86% of a light yellow
1
crystalline compound; mp 153 °C; HPLC purity: 99.95%; UV (nm), λmax/log ε: 345.1/3.67; H-NMR
(DMSO-d6) δ: 3.98 (s, 3H, OCH3), 7.04 (t, 1H, Ar-H), 7.12 (d, 1H, Ar-H), 7.37 (d, J = 16.15 Hz, 1H,
C=C-H), 7.40 (t, 1H, Ar-H), 7.78 (t, 1H, Ar-H), 7.82 (d, 1H, Ar-H), 8.01 (d, 1H, Ar-H), 8.06 (t, 1H,
Ar-H), 8.27 (d, 1H, Ar-H), 8.47 (d, J = 16.15 Hz, 1H, C=C-H).
4-Chloro-2-[(E)-2-(3-methoxyphenyl)vinyl]quinazoline (4c). [63] Yield 81% of a light yellow
1
crystalline compound; mp 137 °C; HPLC purity: 98.62%; UV (nm), λmax/log ε: 342.9/3.64; H-NMR
(DMSO-d6) δ: 3.90 (s, 3H, OCH3), 6.98 (d, 1H, Ar-H), 7.35 (d, J = 15.75 Hz, 1H, C=C-H), 7.35-7.39
(m, 2H, Ar-H), 7.36 (s, 1H, Ar-H), 7.80 (t, 1H, Ar-H), 8.02 (d, 1H, Ar-H), 8.06 (d, 1H, Ar-H), 8.10 (d,
J = 15.82 Hz, 1H, C=C-H), 8.28 (d, 1H, Ar-H).
4-Chloro-2-[(E)-2-(4-methoxyphenyl)vinyl]quinazoline (4d). [63] Yield 51% of a yellow crystalline
compound; mp 130-131 °C, (lit. mp 130-131 °C [65]); HPLC purity: 97.43%; UV (nm), λmax/log ε:
1
339.9/3.64; H-NMR (DMSO-d6) δ: 3.87 (s, 3H, OCH3), 7.03 (d, 2H, Ar-H), 7.20 (d, J = 15.87 Hz,
1H, C=C-H), 7.75 (d, 2H, Ar-H), 7.76 (t, 1H, Ar-H), 7.99 (d, 1H, Ar-H), 8.04 (t, 1H, Ar-H), 8.08
(d, J = 15.89 Hz, 1H, C=C-H), 8.25 (d, 1H, Ar-H).
4-Chloro-2-[(E)-2-(2,4-dimethoxyphenyl)vinyl]quinazoline (4e). [63] Yield 48% of a yellow
crystalline compound; mp 172 °C; HPLC purity: 98.57%; UV (nm), λmax/log ε: 355.0/3.67;
1
IR (KBr, cm-1): 2980, 2938, 1607, 1556, 1504, 1477, 1450, 1384, 1329, 959, 768, 756; H-NMR
[(CD3)2CO] δ: 3.88 (s, 3H, OCH3), 3.98 (s, 3H, OCH3), 6.64 (d, 1H, Ar-H), 6.66 (s, 1H, Ar-H), 7.27
(d, J=16.13 Hz, 1H, C=C-H), 7.75 (d, 1H, Ar-H), 7.60 (t, 1H, Ar-H), 7.98 (d, 1H, Ar-H), 8.02 (t, 1H,
Ar-H), 8.25 (d, 1H, Ar-H), 8.40 (d, J=16.13 Hz, 1H, C=C-H).
4.3. Lipophilicity HPLC determination (capacity factor k / calculated log k)
The HPLC separation module Waters Alliance 2695 XE and Waters Photodiode Array Detector
2996 (Waters Corp., Milford, MA, U.S.A.) were used. The chromatographic column Symmetry® C18
5 μm, 4.6 × 250 mm, Part No. WAT054275, (Waters Corp., Milford, MA, U.S.A.) was used. The
HPLC separation process was monitored by Millennium32® Chromatography Manager Software,

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Waters 2004 (Waters Corp.). The mixture of MeOH p.a. (55.0%) and H2O-HPLC – Mili-Q Grade
(45.0%) was used as a mobile phase. The total flow of the column was 0.9 mL/min, injection 30 μL,
column temperature 30 °C and sample temperature 10 °C. The detection wavelength 210 nm was
chosen. The KI methanolic solution was used for the dead time (tD) determination. Retention times (tR)
were measured in minutes. The capacity factors k were calculated using the Millennium32®
Chromatography Manager Software according to formula k = (tR - tD)/tD, where tR is the retention time
of the solute, whereas tD denotes the dead time obtained via an unretained analyte. The log k values,
calculated from the capacity factor k of the individual compounds, are shown in Table 1.
4.4. Lipophilicity calculations
Log P, i.e., the logarithm of the partition coefficient for n-octanol/water, was calculated using the
programs CS ChemOffice Ultra ver. 10.0 (CambridgeSoft, Cambridge, MA, U.S.A.) and ACD/LogP
ver. 1.0 (Advanced Chemistry Development Inc., Toronto, Canada). Clog P values (the logarithm of
n-octanol/water partition coefficient based on established chemical interactions) were generated by
means of the CS ChemOffice Ultra ver. 10.0 software. The results are shown in Table 1.
4.5. Study of inhibition photosynthetic electron transport (PET) in spinach chloroplasts
Chloroplasts were prepared from spinach (Spinacia oleracea L.) according to Masarovicova and
Kralova [66]. The inhibition of photosynthetic electron transport (PET) in spinach chloroplasts was
determined spectrophotometrically (Genesys 6, Thermo Scientific, U.S.A.) using an artificial electron
acceptor 2,6-dichlorophenol-indophenol (DCIPP) according to Kralova et al. [67] and the rate of
photosynthetic electron transport was monitored as a photoreduction of DCPIP. The measurements
were carried out in phosphate buffer (0.02 mol/L, pH 7.2) containing sucrose (0.4 mol/L), MgCl2
(0.005 mol/L) and NaCl (0.015 mol/L). The chlorophyll content was 30 mg/L in these experiments
and the samples were irradiated (~100 W/m2) from 10 cm distance with a halogen lamp (250 W) using
a 4 cm water filter to prevent warming of the samples (suspension temperature 22 °C). The studied
compounds were dissolved in DMSO due to their limited water solubility. The applied DMSO
concentration (up to 4%) did not affect the photochemical activity in spinach chloroplasts. The
inhibitory efficiency of the studied compounds was expressed by IC50 values, i.e. by molar
concentration of the compounds causing 50% decrease in the oxygen evolution rate relative to the
untreated control. The comparable IC50 value for a selective herbicide 3-(3,4-dichlorophenyl)-1,1-
dimethylurea, DCMU (Diuron®) was about 1.9 μmol/L [68]. The results are summarized in Table 2.
4.6. In vitro antimycobacterial evaluation
Clinical isolates of Mycobacterium avium complex CIT19/06, M. kansasii CIT11/06, M. absessus
CIT21/06 and strain M. smegmatis MC2155 were grown in Middlebrook broth (MB), supplemented
with OADC supplement (Oleic, Albumin, Dextrose, Catalase, Becton Dickinson, U.K.). Identification
of these isolates was performed using biochemical and molecular protocols. At log phase growth, the
10 mL culture was centrifuged at 15,000 RPM for 20 minutes using a bench top centrifuge (Model CR
4-12 Jouan Inc. U.K). Following the removal of the supernatant, the pellet was washed in fresh

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Middlebrook 7H9GC broth and re-suspended in 10 mL of fresh supplemented MB. The turbidity was
adjusted to match McFarland standard No. 1 (3 × 108 CFU) with MB broth. A further 1:20 dilution of
the culture was then performed in MB broth.
The antimicrobial susceptibility of all four mycobacteria was investigated in 96 well plate format.
Here, sterile deionised water (150 µL) was added to all outer-perimeter wells of the plates to minimize
evaporation of the medium in the test wells during incubation. Each dilution (150 µL) was incubated
with each of the mycobacterial species (150 µL). Dilutions of each compound were prepared in
duplicate. For all synthesized compounds, final concentrations ranged from 300 µg/mL to 10 µg/mL.
All compounds were prepared in DMSO and subsequent dilutions were made in supplemented
Middlebrook broth. The plates were sealed with parafilm and were incubated at 37 °C overnight in the
case of M. smegmatis and M. absessus and for five days in the case of M. kansasii and M. avium
complex. Following incubation, a 10% addition of alamarBlue (AbD Serotec) was mixed into each
well and readings at 570 nm and 600 nm were taken, initially for background subtraction and
subsequently after 24 hour re-incubation. The background subtraction is necessary with strongly
coloured compounds which may interfere with the interpretation of any colour change. In
non-interfering compounds, a blue colour in the well was interpreted as an absence of growth, and
a pink colour was scored as growth. The MIC was initially defined as the lowest concentration which
prevented a visual colour change from blue to pink. The results are shown in Table 2.
4.7. In vitro antifungal susceptibility testing
The broth microdilution test [69,70] was used for the assessment of in vitro antifungal activity of
the synthesized compounds against Candida albicans ATCC 44859 (CA), Candida tropicalis 156
(CT), Candida krusei ATCC 6258 (CK), Candida glabrata 20/I (CG), Trichosporon asahii 1188
(TA), Aspergillus fumigatus 231 (AF), Absidia corymbifera 272 (AC), and Trichophyton
mentagrophytes 445 (TM). Fluconazole (FLU) was used as the standard of a clinically used
antimycotic drug. The procedure was performed with twofold dilution of the compounds in RPMI
1640 (Sevapharma a.s., Prague, Czech Republic) buffered to pH 7.0 with 0.165 mol of 3-morpholino-
propane-1-sulfonic acid (MOPS, Sigma, Germany). The final concentrations of the compounds ranged
from 500 to 0.975 μmol/L. Drug–free controls were included. The MIC was defined as an 80% or
greater (IC80) reduction of growth in comparison with the control. The values of MICs were
determined after 24 and 48 h of static incubation at 35 °C. For T. mentagrophytes, the final MICs were
determined after 72 and 120 h of incubation. The results are summarized in Table 3.
Acknowledgements
This study was supported by the Polish Ministry of Science N405 178735, by the Ministry of
Education of the Czech Republic MSM 6215712403 and by the Irish Department of Education and
Science TSR Strand1-06/CR08 and by Sanofi-Aventis Pharma Slovakia.

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References
1. Roth, H.J.; Fenner, H. Arzneistoffe, 3rd, ed.; Deutscher Apotheker Verlag: Stuttgart, Germany,
2000; pp. 51–114.
2. Harris, C.R.; Thorarensen, A. Advances in the discovery of novel antibacterial agents during the
year 2002. Curr. Med. Chem. 2004, 11, 2213–2243.
3. Andries, K.; Verhasselt, P.; Guillemont, J.; Gohlmann, H.W.; Neefs, J.M.; Winkler, H.; Van
Gestel, J.; Timmerman, P.; Zhu, M.; Lee, E.; Williams, P.; de Chaffoy, D.; Huitric, E.; Hoffner,
S.; Cambau, E.; Truffot-Pernot, C.; Lounis, N.; Jarlier, V. A diarylquinoline drug active on the
ATP synthase of Mycobacterium tuberculosis. Science 2005, 307, 223–227.
4. Vangapandu, S.; Jain, M.; Jain, R.; Kaur, S.; Singh, P.P. Ring-substituted quinolines as potential
anti-tuberculosis agents. Bioorg. Med. Chem. 2004, 12, 2501–2508.
5. Carta, A.; Piras, S.; Palomba, M.; Jabes, D.; Molicotti, P.; Zanetti, S. Anti-mycobacterial activity
of quinolones. Triazoloquinolones a new class of potent anti-mycobacterial agents. Anti-Infective
Agents Med. Chem. 2008, 7, 134–147.
6. Sissi, C.; Palumbo, M. The quinolone family: From antibacterial to anticancer agents. Curr. Med.
Chem. Anti-Canc. Agents 2003, 3, 439–450.
7. Bossu, E.; Agliano, A.M.; Desideri, N.; Sestili, I.; Porra, R.; Grandilone, M.; Quaglia, M.G. LTB4
as marker of 5-LO inhibitory activity of two new N-ethoxycarbonyl-4-quinolones. J. Pharm.
Biomed. Anal. 1999, 19, 539–549.
8. Ko, T.C.; Hour, M.J.; Lien, J.C.; Teng, C.M.; Lee, K.H.; Kuo, S.C.; Huang, L.J. Synthesis of
4-alkoxy-2-phenylquinoline derivatives as potent antiplatelet agents. Bioorg. Med. Chem. Lett.
2001, 11, 279–282.
9. Jampilek, J.; Dolezal, M.; Kunes, J.; Vichova, P.; Jun, D.; Raich, I.; O´Connor, R.; Clynes, M.
Synthesis of (2E)-2-methyl-3-(4-{[4-(quinolin-2-ylmethoxy)phenyl]sulfanyl}phenyl)prop-2-enoic
acid (VUFB 20609) and 2-methyl-3-(4-{[4-(quinolin-2-ylmethoxy)phenyl]sulfanyl}phenyl)
propionic acid (VUFB 20584) as potential antileukotrienic agents. J. Pharm. Pharmacol. 2004,
56, 783–794.
10. Jampilek, J.; Dolezal, M.; Kunes, J.; Vichova, P.; Jun, D.; Raich, I.; O´Connor, R.; Clynes, M.
Preparation of 2-(4-{[4-(quinolin-2-ylmethoxy)phenyl]sulfanyl}phenyl)propionic acid (VUFB
20615) and 2-methyl-2-(4-{[4-(quinolin-2-ylmethoxy)phenyl]sulfanyl}phenyl)propionic acid
(VUFB 20623) as potential antileukotrienic agents. Curr. Org. Chem. 2004, 8, 1235–1243.
11. Jampilek, J.; Dolezal, M.; Opletalova, V.; Hartl. J. 5-Lipoxygenase, leukotrienes biosynthesis and
potential antileukotrienic agents. Curr. Med. Chem. 2006, 13, 117–129.
12. Polanski, J.; Zouhiri, F.; Jeanson, L.; Desmaele, D.; d’Angelo, J.; Mouscadet, J.F.; Gieleciak, R.;
Gasteiger, J.; Le Bret. M. Use of Kohonen neural network for rapid screening of ex vivo anti-HIV
activity of styrylquinolines. J. Med. Chem. 2002, 45, 4647–4654.
13. Polanski, J.; Niedbala, H.; Musiol, R.; Tabak, D.; Podeszwa, B.; Gieleciak, R.; Bak, A.; Palka, A.;
Magdziarz, T. Analogues of the styrylquinoline and styrylquinazoline HIV-1 integrase inhibitors:
Design and synthetic problems. Acta Poloniae Pharm. Drug Res. 2004, 61, 3–4.

Molecules 2009, 14
4262
14. Polanski, J.; Niedbala, H.; Musiol, R.; Podeszwa, B.; Tabak, D.; Palka, A.; Mencel, A.; Finster,
J.; Mouscadet, J.F.; Le Bret, M. 5-Hydroxy-8-nitro-6-quinaldic acid as a novel molecular scaffold
for HIV-1 integrase inhibitors. Lett. Drugs Des. Disc. 2006, 3, 175–178.
15. Polanski, J.; Niedbala, H.; Musiol, R.; Podeszwa, B.; Tabak, D.; Palka, A.; Mencel, A.;
Mouscadet, J.F.; Le Bret, M. Fragment based approach for the investigation of HIV-1 integrase
inhibition. Lett. Drugs Des. Disc. 2007, 4, 99–105.
16. Jampilek, J.; Dolezal, M.; Kunes, J.; Buchta, V.; Kralova, K. Quinaldine derivatives: Preparation
and biological activity. Med. Chem. 2005, 1, 591–599.
17. Musiol, R.; Jampilek, J.; Buchta, V.; Niedbala, H.; Podeszwa, B.; Palka, A.; Majerz-Maniecka,
K.; Oleksyn, B.; Polanski, J. Antifungal properties of new series of quinoline derivatives. Bioorg.
Med. Chem. 2006, 14, 3592–3598.
18. Musiol, R.; Jampilek, J.; Kralova, K.; Richardson, D.R.; Kalinowski, D.; Podeszwa, B.; Finster,
J.; Niedbala, H.; Palka, A.; Polanski, J. Investigating biological activity spectrum for novel
quinoline analogues. Bioorg. Med. Chem. 2007, 15, 1280–1288.
19. Musiol, R.; Tabak, D.; Niedbala, H.; Podeszwa, B.; Jampilek, J.; Kralova, K.; Dohnal, J.; Finster,
J.; Mencel, A.; Polanski, J. Investigating biological activity spectrum for novel quinoline
analogues 2: Hydroxyquinolinecarboxamides with photosynthesis inhibiting activity. Bioorg.
Med. Chem. 2008, 16, 4490–4499.
20. Jampilek, J.; Musiol, R.; Pesko, M.; Kralova, K.; Vejsova, M.; Carroll, J.; Coffey, A.; Finster, J.;
Tabak, D.; Niedbala, H.; Kozik, V.; Polanski, J.; Csollei, J.; Dohnal, J. Ring-substituted
4-hydroxy-1H-quinolin-2-ones: Preparation and biological activity. Molecules 2009, 14,
1145–1159.
21. Podeszwa, B.; Niedbala, H.; Polanski, J.; Musiol, R.; Tabak, D.; Finster, J.; Serafin, K.; Wietrzyk,
J.; Boryczka, S.; Mol, W.; Jampilek, J.; Dohnal, J.; Kalinowski, D.; Richardson, D.R.
Investigating the antiproliferative activity of quinoline-5,8-dione analogues on tumour cell lines.
Bioorg. Med. Chem. Lett. 2007, 17, 6138–6141.
22. Draber, W.; Tietjen, K.; Kluth, J.F.; Trebst, A. Herbicides in photosynthesis research. Angew.
Chem. 1991, 3, 1621–1633.
23. Tischer, W.; Strotmann, H. Relationship between inhibitor binding by chloroplasts and inhibition
of photosynthetic electron transport. Biochim. Biophys. Acta 1977, 460, 113–125.
24. Trebst, A.; Draber, W. Structure activity correlations of recent herbicides in photosynthetic
reactions. In Advances in Pesticide Science; Greissbuehler H. Ed.; Pergamon Press: Oxford, UK,
1979; pp. 223–234.
25. Bowyer, J.R.; Camilleri, P.; Vermaas, W.F.J. In Herbicides, Topics in Photosynthesis, vol. 10.
Baker N.R., Percival M.P. Eds.; Elsevier: Amsterdam, The Netherlands, 1991; pp. 27–85.
26. Kralova, K.; Sersen, F.; Kubicova, L.; Waisser, K. Inhibition of photosynthetic electron transport
in spinach chloroplasts by 3-and 4-halogeno substituted benzanilides and thiobenzanilides.
J. Trace Microprobe Techn. 2000, 18, 251–256.
27. Kralova, K.; Sersen, F.; Miletin, M., Dolezal, M. Inhibitory effects of substituted benzanilides on
photosynthetic electron transport in spinach chloroplasts. Chem. Pap. 2002, 56, 214–217.

Molecules 2009, 14
4263
28. Dolezal, M.; Miletin, M.; Kunes, J.; Kralova, K. Synthesis and biological evaluation of some
amides of pyrazine-2-carboxylic acids. Molecules 2002, 7, 363–373.
29. Dolezal, M.; Palek, L.; Vinsova, J.; Buchta, V.; Jampilek, J.; Kralova, K. Substituted
pyrazinecarboxamides: synthesis and biological evaluation. Molecules 2006, 11, 242–256.
30. http://www.who.int/tb/publications/global_report/2008/summary/en/index.html/ (21 September
2009).
31. Espinal, M.A. The global situation of MDR-TB. Tuberculosis 2003, 83, 44–51.
32. Field, S.K.; Cowie, R.L. Lung disease due to the more common nontuberculous mycobacteria.
Chest 2006, 129, 1653–1672.
33. Wagner, D.; Young, L.S. Nontuberculous mycobacterial infections: A clinical review. Infection
2004, 32, 257–270.
34. Morrone, N.; Cruvinel, M.C.; Morrone, N. Jr.; Freire, J.A.; Oliveira, L.M.; Gonçalves, C.
Pneumopatia causada por Mycobacterium kansasii. J. Pneumol. 2003, 29, 341–349.
35. http://www.doctorfungus.org/ (21 September 2009).
36. Gershon, H; Gershon, M; Clarke, D.D. Synergistic mixtures of fungitoxic monochloro- and
dichloro-8-quinolinols against five fungi. Mycopathologia 2004, 158, 131–135.
37. Dardari, Z.; Lemrani, M.; Bahloul, A.; Sebban, A.; Hassar, M.; Kitane, S.; Berrada, M.;
Boudouma, M. Antileishmanial activity of a new 8-hydroxyquinoline derivative designed
7-[5′-(3′-phenylisoxazolino)methyl]-8-hydroxyquinoline: preliminary study. Farmaco 2004, 59,
195–199.
38. Musiol, R.; Podeszwa, B.; Finster, J.; Niedbala, H.; Polanski; J. An efficient microwave-assisted
synthesis of structurally diverse styrylquinolines. Monatsh. Chem. 2006, 137, 1211–1217.
39. Musiol, R.; Niedbala, H.; Majerz-Maniecka, K.; Oleksyn, B.; Polanski, J. Synthesis and structure
of styrylquinolines. Ann. Pol. Chem. Soc. 2005, 1, 118–122.
40. Majerz-Maniecka, K.; Musiol, R.; Nitek, W.; Oleksyn, B.; Mouscadet, J.F.; Le Bret, M.; Polanski
J. Intermolecular interactions in the crystal structures of potential HIV-1 integrase inhibitors.
Bioorg. Med. Chem. Lett. 2006, 16, 1005–1009.
41. Kerns, E.H.; Li, D. Drug-like Properties: Concept, Structure Design and Methods. Elsevier: San
Diego, CA, USA, 2008.
42. Avdeef, A. Physicochemical profiling (permeability, solubility, charge state). Curr. Topics Med.
Chem. 2001, 1, 277–351.
43. Pliska, V. Lipophilicity in drug action and toxicology. In Methods and Principles in Medicinal
Chemistry, 1st ed.; Pliska, V., Testa, B., van der Waterbeemd, H. Eds.; Wiley-VCH: Weinheim,
DE, 1996; Vol. 4, pp. 1–6.
44. Valko, K. Application of high-performance liquid chromatography based measurements of
lipophilicity to model biological distribution. J. Chromatogr. A 2004, 1037, 299–310.
45. Valko, K.; Du, C.M.; Bevan, C.; Reynolds, D.P.; Abraham, M.H. Rapid method for the
estimation of octanol/water partition coefficient (log Poct) from gradient RP-HPLC retention and a
hydrogen bond acidity term (2H). Curr. Med. Chem. 2001, 8, 1137–1146.
46. Cimpan, G.; Irimie, F.; Gocan, S.; Claessens, H.A. Role of stationary phase and eluent
composition on the determination of log P values of N-hydroxyethylamide of aryloxyalkylen and

Molecules 2009, 14
4264
pyridine carboxylic acids by reversed-phase high-performance liquid chromatography.
J. Chromatogr. B 1998, 714, 247–261.
47. Gocan, S.; Cimpan, G.; Comer, J. Lipophilicity measurements by liquid chromatography.
Adv. Chromatogr. 2006, 44, 79–176.
48. Hartmann, T.; Schmitt, J. Lipophilicity – beyond octanol/water: A short comparison of modern
technologies. Drug Discov. Today Technol. 2004, 1, 431–439.
49. Nasal, A.; Siluk, D.; Kaliszan, R. Chromatographic retention parameters in medicinal chemistry
and molecular pharmacology. Curr. Med. Chem. 2003, 10, 381–426.
50. Piraprez, G.; Herent, M.F.; Collin, S. Determination of the lipophilicity of aroma compounds by
RP-HPLC. Flavour Fragr. J. 1998, 13, 400–408.
51. Yamagami, C.; Iwasaki, K.; Ishikawa, A. Hydrophobicity parameters determined by reversed-
phase liquid chromatography. XII. Comparison of capacity factors and octane/methanol-water
partition coefficients for monosubstituted pyrazines, and effect of octanol added to both
partitioning systems. Chem. Pharm. Bull. 1997, 45, 1653–1658.
52. Yamagami, C.; Araki, K.; Ohnishi, K.; Hanasato, K.; Inaba, H.; Aono, M.; Ohta, A. Measurement
and prediction of hydrophobicity parameters for highly lipophilic compounds: Application of the
HPLC column-switching technique to measurement of log P of diarylpyrazines. J. Pharm. Sci.
1999, 88, 1299–1304.
53. Yamagami, C.; Kawase, K.; Iwaki, K. Hydrophobicity parameters determined by reversed-phase
liquid chromatography. XV: Optimal conditions for prediction of log Poct by using RP-HPLC
procedures. Chem. Pharm. Bull. 2002, 50, 1578–1583.
54. Kucerova-Chlupacova, M.; Opletalova, V.; Jampilek, J.; Dolezel, J.; Dohnal, J.; Kunes, J.; Pour,
M.; Kunes, J.; Vorisek, V. New hydrophobicity constants of substituents in pyrazine rings derived
from RP-HPLC Study. Collect. Czech. Chem. Comm. 2008, 73, 1–18.
55. Musiol, R.; Jampilek, J.; Podeszwa, B.; Finster, J.; Tabak, D.; Dohnal, J.; Polanski, J. RP-HPLC
Determination of drug lipophilicity in series of quinoline derivatives. Cent. Eur. J. Chem. 2009, 7,
586–597.
56. Dolezal, M.; Jampilek, J.; Osicka, Z.; Kunes, J.; Buchta, V.; Vichova, P. Substituted
5-aroylpyrazine-2-carboxylic acid derivatives: Synthesis and biological activity. Farmaco 2003,
58, 1105–1111.
57. Jampilek, J.; Vinsova, J.; Dohnal, J. Synthesis and hydrophobic properties of benzoxazoles. In
Proceedings of the 9th International Electronic Conference on Synthetic Organic Chemistry
(ECSOC-9), November 1–30, 2005 [CD-ROM ed.]; Seijas, J.A., Tato, M.P.V., Eds.; MDPI: Basel,
Switzerland, 2005; a008.
58. Jampilek, J.; Vinsova, J.; Dohnal, J. Synthesis and hydrophobic properties of substituted 2-aryl-
5,7-di-tert-butylbenzoxazoles. In Proceedings of the 10th International Electronic Conference on
Synthetic Organic Chemistry (ECSOC-10), November 1–30, 2006 [CD-ROM ed.]; Seijas, J.A.,
Tato, M.P.V., Eds.; MDPI: Basel, Switzerland, 2006; a003.
59. Vinsova, J.; Cermakova, K.; Tomeckova, A.; Ceckova, M.; Jampilek, J.; Cermak, P.; Kunes, J.;
Dolezal, M.; Staud, F. Synthesis and antimicrobial evaluation of new 2-substituted 5,7-di-tert-
butylbenzoxazoles. Bioorg. Med. Chem. 2006, 14, 5850–5865.

Molecules 2009, 14
4265
60. Norrington, F.E.; Hyde, R.M.; Williams, S.G.; Wotton, R. Physicochemical-activity relations in
practice. 1. Rational and self-consistent data bank. J. Med. Chem. 1975, 18, 604–607.
61. Takahata, Y.; Chong, D.P. Estimation of Hammett sigma constants of substituted benzenes
through accurate density-functional calculation of core-electron binding energy shifts. Int. J.
Quantum Chem. 2005, 103, 509–515.
62. Nielsen, K.E.; Pedersen, E.B. Phosphoramides. XII. Phosphorus pentaoxide – amine
hydrochloride as reagents in the synthesis of 4-(3H)-quinazolinones and 4-quinazolinamines.
Acta Chem. Scand. Ser. B 1980, 34, 637–642.
63. Finster, J.; Kalinowski, D.; Musiol, R.; Mrozek, A.; Szurko, A.; Serafin, A.; Kamalapuram, S.K.;
Kovacevic, Z.; Jampilek, J.; Ratuszna, A.; Rezeszowska-Wolny, J.; Richardson, D.R.; Polanski, J.
Investigating anti-proliferative activity of styrylazanaftalenes and azanaftalenediones. Bioorg.
Med. Chem. 2009, submitted.
64. Kovalenko, S.; Belenichev, I.; Nikitin, V.; Karpenko, A. Search for substances with antioxidant
and antiamnestic activities among 2-substituted 4-(3H)-quinazolones. Acta Pol. Pharm. Drug
Design 2003, 60, 275–279.
65. Botros, S.; Shaban, M. Synthesis of some 2-styrylquinazoline derivatives structurally related to
certain chemotherapeutic agents. Pharmazie 1978, 33, 646–647.
66. Masarovicova, E.; Kralova, K. Approaches to measuring plant photosynthesis activity. In
Handbook of Photosynthesis, 2nd Ed.; Pessarakli, M., Eds.; Taylor & Francis Group: Boca Raton,
London-New York-Singapore, 2005; pp. 617–656.
67. Kralova, K.; Sersen, F.; Sidoova, E. Photosynthesis inhibition produced by 2-alkylthio-6-R-
benzothiazoles. Chem. Pap. 1992, 46, 348–350.
68. Fedke, C. Biochemistry and Physiology of Herbicide Action; Springer Verlag: Berlin-
Heidelberg/New York, Germany/US, 1982.
69. Sheehan, D.J.; Espinel-Ingroff, A.; Steele, M.; Webb, C.D. Antifungal susceptibility testing of
yeasts: A brief overview. Clin. Infect. Dis. 1993, 17, 494–500.
70. National Committee for Clinical Laboratory standards. Reference Method for Broth Dilution
Antifungal Susceptibility Testing of Yeast. Approved Standard, NCCLS document M27-A;
NCCLS: Villanova, PA, USA, 1997.
Sample Availability: Samples of the compounds are available from the authors.
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