Design, synthesis and characterization of new 1,2,3-triazolyl pyrazole derivatives as potential antimicrobial agents: Via a Vilsmeier-Haack reaction approach

Article abstract of DOI:10.1039/c6ra06093e

The synthesis of a new series of 3-{5-methyl-1-[2-methyl-3-(trifluoromethyl) phenyl/substituted phenyl]-1H-1,2,3-triazol-4-yl}-1-(aryl)-1H-pyrazole-4-carbaldehyde compounds (5a-n) was carried out via a Vilsmeier-Haack formylation of 4-{(1E)-1-[2-(aryl) hydrazinylidene]ethyl}-5-methyl-1-[2-methyl-3-(trifluoromethyl)phenyl/substituted phenyl]-1H-1,2,3-triazole (4a-n) with a phosphorous oxychloride and DMF mixture. The newly synthesized compounds were characterized using IR, ¹H NMR, ¹³C NMR, mass spectral data and elemental analysis. The newly synthesized compounds were screened for their in vitro anti-bacterial, anti-fungal and anti-oxidant activities. Some of the synthesized compounds displayed a broad spectrum of antimicrobial activities and moderate to good anti-oxidant activities. The anti-bacterial results were further supported by in silico molecular docking studies of these compounds for the inhibition of E. coli MurB enzyme (PDB code: 2MBR) and showed a minimum binding energy and good affinity towards the active pocket comparable with the standard drug Ciproflaxin. Thus, they may be considered as good inhibitors of the E. coli MurB enzyme (PDB code: 2MBR).

Full text of DOI:10.1039/c6ra06093e

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Design, synthesis and characterization of new
1,2,3-triazolyl pyrazole derivatives as potential
antimicrobial agents via a Vilsmeier–Haack
reaction approach†
Cite this: RSC Adv., 2016, 6, 59375
a
Manjunatha Bhat,ab Nagaraja G. K., Reshma Kayarmar,ab Peethamber S. K.c
*
and Mohammed Shafeeulla Rd
The synthesis of a new series of 3-{5-methyl-1-[2-methyl-3-(trifluoromethyl) phenyl/substituted phenyl]-
1H-1,2,3-triazol-4-yl}-1-(aryl)-1H-pyrazole-4-carbaldehyde compounds (5a–n) was carried out via
a
Vilsmeier–Haack formylation of 4-{(1E)-1-[2-(aryl) hydrazinylidene]ethyl}-5-methyl-1-[2-methyl-3-
(trifluoromethyl)phenyl/substituted phenyl]-1H-1,2,3-triazole (4a–n) with a phosphorous oxychloride and
DMF mixture. The newly synthesized compounds were characterized using IR, 1H NMR, 13C NMR, mass
spectral data and elemental analysis. The newly synthesized compounds were screened for their in vitro
anti-bacterial, anti-fungal and anti-oxidant activities. Some of the synthesized compounds displayed
a broad spectrum of antimicrobial activities and moderate to good anti-oxidant activities. The anti-
bacterial results were further supported by in silico molecular docking studies of these compounds for
the inhibition of E. coli MurB enzyme (PDB code: 2MBR) and showed a minimum binding energy and
good affinity towards the active pocket comparable with the standard drug Ciproflaxin. Thus, they may
be considered as good inhibitors of the E. coli MurB enzyme (PDB code: 2MBR).
Received 7th March 2016
Accepted 10th June 2016
DOI: 10.1039/c6ra06093e
www.rsc.org/advances
agents. In this regard, a well known key enzyme MurB, an
NADPH dependent enolpyruvyl reductase,2 which is crucial for
1. Introduction
the growth and bio-synthesis of the peptidoglycan polymeric
layer of bacterial cell walls,3 is an attractive target for inhibi-
tors with the potential to have broad antibacterial activity.4 In
addition, computational biology and bioinformatics play
a major role in designing drug molecules and have the
potential to speed up the drug discovery process. Molecular
docking of the drug molecule with the receptor (target) gives
important information about drug receptor interactions and is
commonly used to nd out the binding orientation of drug
candidates to their protein targets in order to predict the
affinity and activity.5
Anti-oxidants play an important role in the body’s defence
mechanism by regulating the generation and elimination of
reactive oxygen species (ROS) like hydroxyl radicals, superoxide
radicals etc. which are generated from excessive oxidative stress
and normal metabolic activities. The mechanism of regulation
involves detoxication of excess ROS, if not, high concentra-
tions of free radicals damage the cell structures, lipids, nucleic
acids etc. leading to mutations6 and also cause cancer and
Parkinson’s disease.7,8 Thus, the discovery and development of
novel anti-oxidants has attained great importance in organic
chemistry.
During the past few decades, there has been an severe increase
in the population suffering with infectious diseases due to
multi-drug resistance, which oen results from the over-
expression of multi-drug efflux systems and their widespread
usage.1 Microbial infections are the most prominent disease
causing death aer heart attacks in the world, because of their
ability to spread rapidly, combined with their toxicity and
resistance towards existing anti-biotic drugs. Hence there is an
urgent need and challenge to develop more effective, potent
and broad spectrum novel antimicrobial drugs with fewer or
no side effects to cure microbial infections. In this context,
drug discovery has acquired a considerable interest in the
microbial target-based synthesis of novel antimicrobial
aDepartment
of
Studies
in
Chemistry,
Mangalore
University,
Mangalagangothri-574199, Karnataka, India. E-mail: nagarajagk@gmail.com; Tel:
+91-824-2287262
bSeQuent Scientic Limited, No:120 A&B, Industrial Area, Baikampady, New
Mangalore, Karnataka-575 011, India
cDepartment of Bio-Chemistry, Kuvempu University, Jnanasahyadri, Shankaraghatta,
Karnataka 577 451, India
dDepartment of Chemistry, Sahyadri Science College, Shimoga, Karnataka-577 451,
India
In recent years, heterocyclic compounds containing nitrogen
have played an important role in agrochemicals and
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c6ra06093e
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 59375–59388 | 59375

View Article Online
RSC Advances
Paper
pharmaceuticals. The basic heterocyclic rings present in various
medicinal agents are mainly 1,2,3-triazoles and pyrazoles. Most
literature studies have revealed that 1,2,3-triazoles are the key
moieties in heterocyclic chemistry and are an important struc-
tural backbone of various natural and synthetic biologically
active molecules. They are known to possess a wide range of
pharmacological activities like anti-microbial,9,10 anti-inam-
matory,11 anti-tubercular,12 anti-diabetic,13 anti-malarial,14 anti-
oxidant,15 and anti-cancer activities.16 On the other hand, the
pyrazole moiety is of great importance to chemists as well as
biologists as its derivatives have been found to exhibit a variety
of biological and pharmacological activities, including antimi-
crobial,17,18 anti-inammatory,18 anti-oxidant,19 analgesic,20
anticonvulsant,20 and anticancer21 effects (Fig. 1).
Keeping these biologically active molecules in mind, we
hereby report the synthesis of some novel 1,2,3-triazole bearing
pyrazoles as a key nucleus and evaluate their anti-microbial and
anti-oxidant potentials with the hope of improving the biolog-
ical activities. Most of the compounds exhibit good biological
activities. Furthermore, in silico molecular docking studies of
the compounds were also carried out to support the in vitro anti-
bacterial results.
2. Results and discussion
2.1. Chemistry
The synthetic protocol for the title compounds, 3-{5-methyl-1-[2-
methyl-3-(triuoromethyl) phenyl/substituted phenyl]-1H-1,2,3-
triazol-4-yl}-1-(aryl)-1H-pyrazole-4-carbaldehyde (5a–n) is out-
lined in Scheme 1, and were synthesized using a Vilsmeier–
Haack formylation of 4-{(1E)-1-[2-(aryl) hydrazinylidene]ethyl}-5-
methyl-1-[2-methyl-3-(triuoromethyl)phenyl/substituted
phenyl]-1H-1,2,3-triazole (4a–n) with a phosphorous oxychloride
and DMF mixture in good yields (70–75%). The key starting
materials 4-{(1E)-1-[2-(aryl) hydrazinylidene] ethyl}-5-methyl-1-
[2-methyl-3-(triuoromethyl) phenyl/substituted phenyl]-1H-
1,2,3-triazole (4a–n) were synthesized using multi-step reactions
following literature procedures.
The structures of all the synthesized compounds (5a–n) were
established on the basis of their spectral (IR, NMR and mass) and
elemental (C, H and N) analyses. The analytical and spectral data
of all the synthesized compounds were in full agreement with the
proposed structures and are also discussed for a representative
example, compound 5c. The IR spectrum of 5cshowed an
absorption peak at 3071 cmꢀ1 assigned to the aromatic C–H
Fig. 1 Biologically active 1,2,3-triazole and pyrazole pharmacopores.
59376 | RSC Adv., 2016, 6, 59375–59388
This journal is © The Royal Society of Chemistry 2016

View Article Online
Paper
RSC Advances
Scheme 1 Synthetic scheme for compounds 5a–n.
stretch. The peak for C]N was observed at 1568 cmꢀ1. The peaks to the presence of C–F and C–Cl bonds, respectively. The absence
at 1665 and 1211 cmꢀ1 were assigned to C]O and C–O stretches, of absorption bands at 3274 cmꢀ1 and 1620 cmꢀ1 corresponding
respectively. The medium absorptions at 1167, 715 cmꢀ1 were due to –NH2 and –C]O stretching frequencies, respectively, clearly
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 59375–59388 | 59377

View Article Online
RSC Advances
Paper
Table 1 Characterization data of the compounds 5(a–n)
C, H, N analysis (%) found (calculated)
Compd.
Ar
Mol. formula
Mol. wt.
M.P. (ꢁC)
Yield (%)
C
H
N
R1, R2 ¼ Cl
5a
5b
5c
5d
5e
5f
Phenyl
4-Cl-phenyl
2,4-Dinitro phenyl
2,4,6-Trichloro phenyl
Phthalazinyl
C
21H14Cl2F3N5O
480.2
514.7
570.2
583.6
532.3
599.3
525.2
185–187
193–195
225–227
220–222
228–230
252–254
218–220
71
73
70
75
71
70
74
52.45 (52.52)
48.91 (49.00)
44.12 (44.23)
43.25 (43.22)
51.85 (51.90)
50.02 (50.10)
48.10 (48.02)
2.92 (2.94)
2.52 (2.55)
2.08 (2.12)
1.92 (1.90)
2.62 (2.65)
2.29 (2.35)
2.52 (2.49)
14.52 (14.58)
13.53 (13.61)
17.82 (17.91)
12.03 (12.00)
18.40 (18.42)
13.92 (14.02)
16.08 (16.00)
C21H13Cl3F3N5O
C21H12Cl2F3N7O5
C21H11Cl5F3N5O
C23H14Cl2F3N7O
8-CF3-quinyl
4-Nitro phenyl
C25H14Cl2F6N6O
C21H13Cl2F3N6O3
5g
R1, R2 ¼ H
5h
5i
Phenyl
4-Cl-phenyl
2,4-Dinitro phenyl
2,4,6-Trichloro phenyl
Phthalazinyl
C21H16F3N5O
411.4
445.8
501.4
514.7
463.4
530.4
456.4
175–177
185–187
215–217
212–214
224–226
246–248
216–218
74
73
70
72
74
70
72
61.22 (61.31)
56.48 (56.57)
50.40 (50.31)
49.07 (49.00)
59.55 (59.61)
56.52 (56.61)
55.35 (55.27)
3.85 (3.92)
3.30 (3.39)
2.90 (2.81)
2.62 (2.55)
3.43 (3.48)
2.98 (3.04)
3.30 (3.31)
17.10 (17.02)
15.62 (15.71)
19.62 (19.56)
13.70 (13.61)
21.12 (21.16)
15.78 (15.84)
18.38 (18.41)
C
21H15ClF3N5O
C21H14F3N7O5
C21H13Cl3F3N5O
5j
5k
5l
5m
5n
C23H16F3N7O
C25H16F6N6O
C21H15F3N6O3
8-CF3-quinyl
4-Nitro phenyl
revealed the formation of 1,2,3-triazolyl pyrazole aldehydes (5a–n). 1,2,3-triazole and the 2,3-dichloro-6-methyl-5-(triuoromethyl)
The 1H NMR spectrum of 5c showed two singlets at d (ppm) 2.09 phenyl ring and the aldehyde carbon of the pyrazole ring,
1
and 2.35 which were assigned to the two methyl protons of the respectively, along with other characteristic signals. The IR, H
1,2,3-triazole ring and 2,3-dichloro-6-methyl-5-(triuoromethyl) NMR and 13C NMR spectra of the other compounds showed
phenyl, respectively. The two singlet signals at d 9.42 and 10.64 similar characteristic properties. The physicochemical data of the
were assigned to the aromatic and aldehyde protons of the pyr- compounds (5a–n) are presented in Table 1.
azole ring, respectively, along with other characteristic signals.
Two distinct doublets at d 8.70 and 8.94 (J ¼ 6.8 Hz) and a singlet
2.2. Biological studies
at d 8.4 integrating for four protons were assigned to protons of
the 2,4-dinitro phenyl and the 2,3-dichloro-6-methyl-5-
(triuoromethyl) phenyl moieties, respectively. The signals due
to the NH protons of the corresponding hydrazones disappeared.
The 13C NMR spectrum of 5c showed signals at d (ppm) 8.74,
14.33 and 187.31 corresponding to the two methyl carbons of
2.2.1. In vitro antimicrobial activity. The antimicrobial
activities of the newly synthesized compounds (5a–n) were
tested against four different bacteria and three different
funguses. Two Gram-positive strains, Staphylococcus aureus
(ATCC 25923) and Bacillus subtilis (ATCC 6051), and two Gram-
Table 2 Determination of antibacterial activities of the synthesized compounds 5a–na
Organic compounds
Escherichia coli
1
Staphylococcus aureus
Pseudomonas aeruginosa
Bacillus subtilis
1
Conc. in mg mlꢀ1
0.5
1
0.5
1
0.5
0.5
ZOI in mm
mm
mm
mm
mm
mm
mm
mm
mm
Control
00
00
00
00
Ciproaxin
18 ꢂ 0.2
12 ꢂ 0.3
12 ꢂ 0.2
16 ꢂ 0.2
15 ꢂ 0.3
16 ꢂ 0.3
13 ꢂ 0.1
14 ꢂ 0.3
14 ꢂ 0.2
09 ꢂ 0.4
13 ꢂ 0.4
09 ꢂ 0.4
13 ꢂ 0.3
17 ꢂ 0.1
13 ꢂ 0.4
13 ꢂ 0.1
09 ꢂ 0.4
10 ꢂ 0.2
14 ꢂ 0.3
13 ꢂ 0.4
14 ꢂ 0.1
10 ꢂ 0.2
12 ꢂ 0.2
13 ꢂ 0.3
07 ꢂ 0.3
12 ꢂ 0.3
07 ꢂ 0.3
12 ꢂ 0.3
14 ꢂ 0.2
12 ꢂ 0.3
17 ꢂ 0.2
12 ꢂ 0.3
13 ꢂ 0.3
16 ꢂ 0.3
16 ꢂ 0.1
16 ꢂ 0.2
13 ꢂ 0.2
12 ꢂ 0.3
15 ꢂ 0.4
08 ꢂ 0.3
15 ꢂ 0.5
08 ꢂ 0.3
13 ꢂ 0.3
16 ꢂ 0.2
15 ꢂ 0.5
14 ꢂ 0.2
11 ꢂ 0.4
11 ꢂ 0.2
14 ꢂ 0.2
14 ꢂ 0.4
14 ꢂ 0.3
11 ꢂ 0.3
10 ꢂ 0.2
14 ꢂ 0.2
07 ꢂ 0.2
14 ꢂ 0.3
07 ꢂ 0.2
12 ꢂ 0.3
14 ꢂ 0.3
14 ꢂ 0.3
17 ꢂ 0.2
12 ꢂ 0.1
12 ꢂ 0.2
16 ꢂ 0.2
16 ꢂ 0.3
16 ꢂ 0.1
12 ꢂ 0.3
13 ꢂ 0.3
15 ꢂ 0.2
10 ꢂ 0.2
15 ꢂ 0.4
10 ꢂ 0.2
14 ꢂ 0.3
16 ꢂ 0.3
15 ꢂ 0.4
15 ꢂ 0.2
11 ꢂ 0.3
10 ꢂ 0.3
13 ꢂ 0.4
13 ꢂ 0.6
14 ꢂ 0.2
10 ꢂ 0.4
11 ꢂ 0.2
14 ꢂ 0.2
07 ꢂ 0.2
14 ꢂ 0.2
07 ꢂ 0.2
13 ꢂ 0.2
14 ꢂ 0.3
14 ꢂ 0.2
20 ꢂ 0.4
15 ꢂ 0.2
15 ꢂ 0.2
18 ꢂ 0.3
18 ꢂ 0.5
19 ꢂ 0.2
14 ꢂ 0.3
15 ꢂ 0.3
17 ꢂ 0.3
11 ꢂ 0.2
17 ꢂ 0.3
11 ꢂ 0.2
16 ꢂ 0.2
19 ꢂ 0.2
17 ꢂ 0.3
18 ꢂ 0.3
13 ꢂ 0.3
12 ꢂ 0.3
15 ꢂ 0.3
15 ꢂ 0.2
16 ꢂ 0.2
12 ꢂ 0.1
12 ꢂ 0.2
15 ꢂ 0.2
08 ꢂ 0.3
15 ꢂ 0.5
08 ꢂ 0.3
13 ꢂ 0.4
16 ꢂ 0.2
15 ꢂ 0.5
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
a
Experiments were performed in triplicate and values are expressed as mean ꢂ SD.
59378 | RSC Adv., 2016, 6, 59375–59388
This journal is © The Royal Society of Chemistry 2016

View Article Online
Paper
RSC Advances
Table 3 Minimum inhibitory concentration (MIC) (mg mlꢀ1) of the synthesized compoundsa
Staphylococcus
aureus
Pseudomonas
aeruginosa
Bacillus
subtilis
Organic compounds
Escherichia coli
5a
5b
5c
5d
5e
5f
5g
5h
5j
5l
5m
5n
25 ꢂ 0.6
27 ꢂ 0.5
13 ꢂ 0.2
14 ꢂ 0.2
10 ꢂ 0.3
30 ꢂ 0.6
33 ꢂ 0.7
13 ꢂ 0.3
35 ꢂ 0.6
12 ꢂ 0.4
15 ꢂ 0.4
37 ꢂ 0.8
06 ꢂ 0.3
23 ꢂ 0.5
25 ꢂ 0.3
12 ꢂ 0.1
10 ꢂ 0.2
11 ꢂ 0.2
26 ꢂ 0.6
25 ꢂ 0.6
15 ꢂ 0.4
28 ꢂ 0.6
14 ꢂ 0.2
12 ꢂ 0.3
26 ꢂ 0.7
02 ꢂ 0.2
24 ꢂ 0.6
26 ꢂ 0.4
11 ꢂ 0.2
12 ꢂ 0.3
13 ꢂ 0.4
24 ꢂ 0.5
25 ꢂ 0.6
12 ꢂ 0.2
27 ꢂ 0.6
12 ꢂ 0.3
14 ꢂ 0.4
25 ꢂ 0.5
05 ꢂ 0.2
22 ꢂ 0.5
23 ꢂ 0.4
10 ꢂ 0.2
11 ꢂ 0.1
11 ꢂ 0.4
23 ꢂ 0.6
25 ꢂ 0.5
15 ꢂ 0.6
26 ꢂ 0.5
15 ꢂ 0.3
13 ꢂ 0.5
27 ꢂ 0.7
03 ꢂ 0.3
Ciproaxin
a
Experiments were performed in triplicate and values are expressed as mean ꢂ SD.
negative strains, Escherichia coli (ATCC 25922) and Pseudomonas statically at the aforementioned temperatures for the microor-
aeruginosa (ATCC 27853), were studied. All bacterial strains ganisms for 18–24 h so that all cells were in the stationary
ꢁ
were maintained on nutrient agar medium at 37 C. The fungi phase. The susceptibility of the test organism to the compounds
Aspergillus avus, Chrysosporium keratinophilum and Candida was determined using the well plate technique. The bacterial
albicans (MTCC 227) was used in this study. All fungi strains suspensions were diluted tenfold in sterilized distilled water,
ꢁ
were maintained on potato dextrose agar (PDA) at 25 C.
and 0.1 ml from the appropriate dilution was spread and plated
The synthesized compounds was rst dissolved in DMSO to on nutrient agar in order to give a population of approximately
a different concentration (1 and 0.5 mg mlꢀ1), and then steril- 106 cfu per plate. Six millimeter diameter wells were then
ized by ltration through 0.22 mm Millipore lters. The anti- punched carefully using a sterile cork borer and 30 mL of the test
bacterial activity of the newly synthesized compounds (5a–n) solutions of different concentrations were added into each
was determined using a well plate method in nutrient agar labeled well. The same procedure was repeated for the different
media.22 The compounds were tested against a panel of patho- microorganisms. Each experiment was carried out in triplicate.
genic microorganisms, including E. coli, B. subtilis, S. aureus Aer incubation, the inhibition zone was measured and the
and P. aeruginosa. Microorganism strains were maintained on values for DMSO were subtracted to get the actual values.
nutrient agar medium at 37 ꢁC. The cultures were inoculated in Ciproaxin was used as the standard drug. The MIC (minimum
fresh 10 ml nutrient broth to yield an initial suspension of inhibitory concentration) was determined according to the
approximately 10–100 cfu mlꢀ1. All broths were then incubated method described, with suitable modications.23 The MIC
Table 4 Determination of the antifungal activity of the synthesized compounds 5a–na
Organic compound
Aspergillus avus
1
Chrysosporium keratinophilum
Candida albicans
1
Conc. in mg mlꢀ1
0.5
1
0.5
0.5
ZOI in mm
mm
mm
mm
mm
mm
mm
Control
00
00
00
Fluconazole
13 ꢂ 0.3
05 ꢂ 0.2
09 ꢂ 0.3
04 ꢂ 0.2
08 ꢂ 0.3
06 ꢂ 0.3
04 ꢂ 0.2
07 ꢂ 0.3
09 ꢂ 0.3
12 ꢂ 0.2
11 ꢂ 0.3
09 ꢂ 0.3
08 ꢂ 0.2
03 ꢂ 0.1
02 ꢂ 0.1
10 ꢂ 0.4
02 ꢂ 0.3
08 ꢂ 0.2
02 ꢂ 0.3
07 ꢂ 0.2
04 ꢂ 0.2
02 ꢂ 0.3
05 ꢂ 0.2
06 ꢂ 0.3
09 ꢂ 0.3
09 ꢂ 0.2
08 ꢂ 0.2
06 ꢂ 0.3
02 ꢂ 0.1
01 ꢂ 0.1
17 ꢂ 0.4
06 ꢂ 0.2
13 ꢂ 0.2
06 ꢂ 0.1
13 ꢂ 0.2
08 ꢂ 0.3
06 ꢂ 0.1
12 ꢂ 0.3
12 ꢂ 0.2
15 ꢂ 0.3
15 ꢂ 0.2
13 ꢂ 0.2
13 ꢂ 0.3
04 ꢂ 0.3
04 ꢂ 0.3
15 ꢂ 0.5
05 ꢂ 0.2
11 ꢂ 0.3
03 ꢂ 0.1
11 ꢂ 0.3
05 ꢂ 0.3
03 ꢂ 0.1
10 ꢂ 0.3
10 ꢂ 0.2
13 ꢂ 0.3
14 ꢂ 0.4
11 ꢂ 0.3
12 ꢂ 0.2
01 ꢂ 0.2
01 ꢂ 0.2
22 ꢂ 0.2
04 ꢂ 0.2
16 ꢂ 0.1
07 ꢂ 0.3
16 ꢂ 0.1
08 ꢂ 0.2
07 ꢂ 0.3
14 ꢂ 0.3
15 ꢂ 0.3
20 ꢂ 0.3
19 ꢂ 0.2
16 ꢂ 0.1
16 ꢂ 0.3
04 ꢂ 0.3
04 ꢂ 0.3
20 ꢂ 0.3
02 ꢂ 0.2
14 ꢂ 0.1
05 ꢂ 0.3
14 ꢂ 0.1
04 ꢂ 0.1
05 ꢂ 0.3
12 ꢂ 0.2
12 ꢂ 0.3
18 ꢂ 0.1
18 ꢂ 0.2
14 ꢂ 0.1
13 ꢂ 0.2
02 ꢂ 0.3
02 ꢂ 0.3
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
a
Experiments were performed in triplicate and values are expressed as mean ꢂ SD.
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 59375–59388 | 59379

View Article Online
RSC Advances
Paper
mm and MIC ¼ 10–15 mg mlꢀ1) with respect to the standard
drug Ciproaxin (ZOI ¼ 13–20 mm and MIC ¼ 02–06 mg mlꢀ1).
Similarly, the derivatives 5a, 5b, 5f, 5g, 5j and 5n showed good
activities against the tested bacterial strains with ZOI ¼ 9–17
mm and MIC ¼ 22–37 mg mlꢀ1 when compared to the standard
drug Ciproaxin. The compounds 5i and 5k were non-
signicant and were unable to show any inhibitory action
towards the panel of human pathogens.
Among the fourteen newly synthesized compounds, few
compounds inhibited the growth of most of the human path-
ogenic fungi tested (Table 4). The sensitivity of the fungal
strains varied according to the species. Among the tested fungi,
C. albicans was highly sensitive compared to the other fungi
species. A. avus and C. keratinophilm showed some differing
responses to each organic compound. The compounds 5i and 5j
showed very good activity with ZOI ¼ 9–20 mm when compared
to the standard drug Flucanazole with ZOI ¼ 10–22 mm. On the
other hand, the derivatives 5b, 5d and 5k showed moderate
activity with ZOI ¼ 7–16 mm when compared to the standard
drug Flucanazole. The rest of the synthesized compounds failed
to show good and comparable antifungal activity when
compared to the standard drug Fluconazole.
Table 5 Antioxidant activity of the synthesized compounds 5a–n
using a DPPH method
IC50
ꢂ
Concentration 15.62–62.5
mg mlꢀ1 % inhibition
SD (mg
Compound
mlꢀ1) DPPH method
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
35.0–87.12
18.90–89.42
2.57–58.2
2.6–81.42
38.81–90.83
2.7–81.07
21.85–80.87
40.7–88.08
3.4–80.12
6.85–85.2
0.4–59.84
42.7–91.18
32.7–80.08
6.81–85.5
44.95–95.5
—
16.36 ꢂ 1.633
30.41 ꢂ 1.241
255.13 ꢂ 3.697
72.13 ꢂ 1.189
15.33 ꢂ 1.727
43.76 ꢂ 1.898
32.34 ꢂ 1.731
18.23 ꢂ 1.629
62.9 ꢂ 1.286
42.51 ꢂ 1.536
243 ꢂ 3.052
14.48 ꢂ 1.629
34.91 ꢂ 1.629
42.48 ꢂ 1.532
12.7 ꢂ 0.68
Ascorbic acid
Blank
—
Table 6 Parameters used for docking studies
The structure–activity relationship of compounds 5a–n
revealed that the compounds 5c, 5d, 5e, 5h, 5l and 5m con-
taining 2-methyl-3-triuoromethyl-5,6-dichloro/dihydro phenyl
substituents in the rst position of the 1,2,3-triazole ring, and
2,4-dinitro phenyl, 2,4,6-trichloro phenyl, pthalazinyl, phenyl
and 8-triuoromethyl quinyl substituents in the second posi-
tion of the pyrazole ring, respectively, were found to be more
potent antibacterial agents, while compounds 5i and 5j bearing
the 2-methyl-3-triuoromethyl phenyl substituent in the rst
position of the 1,2,3-triazole ring and 4-chloro phenyl and 2,4-
dinitro phenyl substituents in the 2nd position of the pyrazole
ring, respectively, were found to be more potent antifungal
agents than the remaining compounds. The structure–activity
relationship (SAR) further reveals that the presence of multi
electron-withdrawing, liphophilic and electronegative groups
like uorine, chlorine, nitro and triuoromethyl on phenyl
rings and electron-donating groups like phthalazinyl and quinyl
generally may be more benecial than the less substituted or
unsubstituted groups on the phenyl rings.
Correlation type
Grid dimension
Receptor range
Ligand range
Twist range
Shape only
0.6
180
180
360
40
Distance range
value, representing the lowest concentration that completely
inhibited the formation of visible growth, was evaluated aer 18
h of incubation at 37 C.
ꢁ
Antifungal studies of the newly synthesized compounds (5a–
n) were determined using a well plate method against A. avus,
C. keratinophilum and C. albicans. Normal saline was used to
make a suspension of the spores of the fungal strains for
lawning.24 A loop full of a particular fungal strain was trans-
ferred to 3 ml saline to get a suspension of the corresponding
species. 20 ml of agar media was poured into each Petri dish. An
excess of suspension was decanted and the plates were dried by
placing in an incubator at 37 ꢁC for 1 h. Using a sterile cork
borer and punching carefully, wells were made on these seeded
agar plates and different concentrations of the test compounds
in DMSO were added into each labeled well. A control was also
prepared for the plates in the same way using solvent DMSO.
The Petri dishes were prepared in triplicate and maintained at
25 ꢁC for 72 h. The antifungal activity was determined by
measuring the diameter of the inhibition zone. The activity of
each compound was compared with uconazole as standard.
The antibacterial activity evaluation of the newly synthesized
compounds revealed that most of the tested compounds
exhibited a moderate to very good antibacterial activity against
all the different tested strains (Tables 2 and 3). Among them,
compounds 5c, 5d, 5e, 5h, 5l and 5m exhibited very good
activities against all four tested bacterial strains (ZOI ¼ 13–19
2.2.2. In vitro anti-oxidant activity. In order to investigate
the possible biological studies, the synthesized compounds (5a–
n), were also screened for their in vitro antioxidant activity using
a
1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging
method with ascorbic acid as the standard drug.25 The spec-
trophotometric assay uses the stable radical DPPH as a reagent.
21 mg of DPPH was dissolved in methanol in a 100 ml
volumetric ask to get a DPPH stock solution. Furthermore, 18
ml of the above DPPH stock solution was pipetted out into a 100
ml volumetric ask and diluted with methanol to obtain a 100
mM DPPH working solution.
The sample solution was prepared by mixing 1 ml of various
concentrations of the test compounds (5a–n) (62.5 mg mlꢀ1
,
31.25 mg mlꢀ1, 15.62 mg mlꢀ1) in DMSO with 5 ml DPPH working
solution (100 mM) in each test tube. 1 ml of DMSO was taken in
a test tube and then 5 ml of DPPH working solution (100 mM)
59380 | RSC Adv., 2016, 6, 59375–59388
This journal is © The Royal Society of Chemistry 2016

View Article Online
Paper
RSC Advances
Fig. 2 Interaction and binding energy of compounds 5a–n and Ciproflaxin with E. coli Mur B enzyme (PDB code 2MBR).
was added and kept as a control sample. 1 ml of DMSO was min and the absorbance was determined using a UV spectro-
taken in a test tube and then 5 ml of methanol was added and photometer at 517 nm. The % inhibition was calculated using
ꢁ
kept as blank. These test tubes were incubated at 37 C for 20 the formula,
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 59375–59388 | 59381

View Article Online
RSC Advances
Paper
Table 7 Docking scores
% inhibition ¼ [(Abscontrol ꢀ Abssample)/Abscontrol] ꢃ 100
Receptor PDB
code
Energy values
where Abscontrol is the absorbance of the control reaction (con-
taining all reagents, except the test compound) and Abssample is
the absorbance of the test compound. Tests were carried out in
triplicate. The IC50 value was obtained by plotting a graph of %
inhibition on the y-axis and concentration on the x-axis.25
Evaluation of the antioxidant activity revealed that most of
the tested compounds exhibited a moderate to good DPPH
radical scavenging ability compared with the positive control,
ascorbic acid (Table 5). Among the synthesized compounds,
Compound code
(kcal molꢀ1
)
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
2MBR
ꢀ233.43
ꢀ231.65
ꢀ289.19
ꢀ278.81
ꢀ290.84
ꢀ231.87
ꢀ240.72
ꢀ277.56
ꢀ229.81
ꢀ240.28
ꢀ239.84
ꢀ281.72
ꢀ278.81
ꢀ234.88
ꢀ237.66
compounds 5a, 5e, 5h and 5l bearing
a 2-methyl-3-
triuoromethyl-5,6-dichloro/dihydro phenyl substituent in the
rst position on the 1,2,3-triazole ring, and phenyl and phtha-
lazine at the second position of the pyrazole ring, respectively,
were found to be more effective and have a potent DPPH radical
scavenging ability with IC50 values ranging from 14.48–18.23
mM compared to the standard drug ascorbic acid with an IC50
value of 12.27 mM at 31.5 mg mlꢀ1. The remaining compounds
showed moderate to non-signicant radical scavenging activity
with IC50 values in the range of 30.41–255 mM. Generally, it was
observed that the compounds with phenyl and electron
donating groups like phthalazine on the second position of the
pyrazole ring were found to have a potent radical scavenging
ability.
Std. Ciproaxin
2.2.3. Molecular docking studies. To explore and support
the antibacterial activity, molecular docking of the synthesized
compounds 5a–n was carried out using E. coli MurB enzyme
(PDB code: 2MBR). E. coli MurB enzyme (PDB code: 2MBR) is
essential for the viability of bacterial cells.26,27 E. coli MurB (PDB
code: 2MBR) is an attractive target for inhibitors with the
potential to have broad antibacterial activity. The enzymes
involved in peptidoglycan biosynthesis are among the best
known targets in the search for new antibiotics.28 Because of
this, we selected the E. coli MurB enzyme (PDB code: 2MBR) as
the target receptor.
Fig. 3 Interaction of 5h and 5l with E. coli MurB (2MBR), bound within
the active site of E. coli MurB (2MBR) (shown as a ball- and-stick
model, with bonds colored brown and nitrogen atoms colored blue,
oxygen colored red, and fluorine colored white).
Fig. 4 Binding of 5h and 5l with the amino acid residues of E. coli MurB (2MBR).
59382 | RSC Adv., 2016, 6, 59375–59388
This journal is © The Royal Society of Chemistry 2016

View Article Online
Paper
RSC Advances
Fig. 5 2-Dimensional (2D) interactions of compounds 5a–n and Ciproflaxin with the active site amino acids of E. coli MurB enzyme (PDB Code:
2MBR).
For macromolecular docking studies, chemical structures of optimization was performed using Chem. Draw 3D Ultra so-
the synthesized ligands (5a–n), metal complexes and standard ware and stored as .pdb les. Hex docking was carried out by
Ciproaxin were drawn using Chem. Draw Ultra. 3D setting suitable parameters, outlined in Table 6 and this
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 59375–59388 | 59383

View Article Online
RSC Advances
Paper
docking score can be interpreted as the interaction energy. A coli MurB (PDB code: 2MBR) enzyme, thereby potentially
more negative E-total energy value implies that a strong inter- inhibiting the bacterial infection-causing property of the
action exists between drug and receptor which leads to the receptor (Fig. 3 and 4). The other ligands (compounds) 5a–n in
inhibition of receptor activity. Molecular docking work was the series showed similar interactions as shown in Fig. 5. The
performed with the Hex molecular modeling package version obtained results may provide a sufficient explanation and
8.0. The three dimensional crystal structure of the E. coli MurB good compromise between docking scores and in vitro results
enzyme (PDB code: 2MBR) was used throughout the work. The of antibacterial activity.
ligands were converted to 2D and 3D energy-minimized
conformations using Hex 3D Ultra 8.0. and the conformation
was visualized using Acceryl Discovery Studio 3.1 Client.
3. Conclusion
Docking studies of the synthesized compounds (5a–n) were
In conclusion,
a new series of 3-{5-methyl-1-[2-methyl-3-
evaluated against E. coli MurB enzyme (PDB code: 2MBR)
which is known to be responsible for causing antimicrobial
infections. In the present study, an attempt was made to
evaluate their antibacterial properties, so we selected E. coli
MurB enzyme (PDB code: 2MBR) which is involved in causing
bacterial infections. Ciproaxin drug was used as the standard
for our docking studies which is known to be a potential
inhibitor of E. coli MurB enzyme (PDB code: 2MBR) (Fig. 2).
The obtained docking scores are tabulated in Table 7. For the
E. coli MurB enzyme (PDB code: 2MBR) receptor, most of the
(triuoromethyl) phenyl/substituted phenyl]-1H-1,2,3-triazol-4-
yl}-1-(aryl)-1H-pyrazole-4-carbaldehyde compounds (5a–n) were
synthesized via Vilsmeier–Haack formylation of 4-{(1E)-1-[2-
(aryl)
hydrazinylidene]ethyl}-5-methyl-1-[2-methyl-3-
(triuoromethyl)phenyl/substituted phenyl]-1H-1,2,3-triazole
(4a–n) in quantitative yields and evaluated for their in vitro
antimicrobial and antioxidant studies. Within this series,
compounds 5c, 5d, 5e, 5h, 5l and 5m were found to be potent
and broad spectrum antibacterial agents comparable with
respect to the standard drug Ciproaxin. Meanwhile the
compounds 5i and 5j were found to be good antifungal agents
against the standard drug Flucanazole. Antioxidant studies
revealed that the compounds 5a, 5e, 5h and 5l showed good
radical scavenging activity against the positive control ascorbic
acid. In order to support the in vitro antibacterial results, the
synthesized compounds were docked in to the plausible target
E. coli MurB enzyme (PDB code: 2MBR). The docking scores or
the interaction binding energies of the target enzyme supported
the antibacterial inhibiting activity of compounds 5c, 5d, 5e and
5m. All these results could be useful to evaluate antibacterial
inhibitors and can be considered as lead compounds for the
development of antibacterial agents for the treatment of
bacterial infection.
synthesized compounds (5a–n) exhibited
a comparable
binding interaction energy with the lowest docking score
compared to the standard drug Ciproaxin. Among all the
synthesized compounds docked, derivatives 5c, 5d, 5e, 5h, 5l
and 5m showed more least E-total values ꢀ289.19, ꢀ278.81,
ꢀ290.84, ꢀ277.56, ꢀ281.72 and ꢀ278.81 kcal molꢀ1 compared
with the standard drug Ciproaxin (E-total value ꢀ237.66 kcal
molꢀ1) and had a signicantly better inhibiting ability towards
the E. coli MurB enzyme (PDB code: 2MBR) receptor, which
binds to the active site of receptors through hydrogen bonds
and other interactions with a variety of amino acids of the
active site, thereby potentially inhibiting the bacterial
infection-causing property of the receptor. Meanwhile, the
compounds 5a, 5b, 5f, 5g, 5j and 5n showed comparable E-
total values ranging from ꢀ231.65 to ꢀ240.72 kcal molꢀ1
compared with the standard drug Ciproaxin (E-total ¼
ꢀ237.66 kcal molꢀ1) (Table 7). Furthermore, the docking
studies of the ligand molecules 5a–n with E. coli MurB (PDB
4. Experimental
4.1. General
code: 2MBR) enzyme revealed that all the compounds exhibi- All solvents used were of analytical grade and the reagents were
ted bonding with various amino acids in the active pockets. used as purchased. All melting points were determined using an
The estimated binding affinity of ligands 5a–n with the open capillary method and were uncorrected. IR spectra were
complex hydrogen network with a plethora of amino acids obtained in a KBr disc on a Shimadzu FT-IR 157 spectrometer.
includes Arg214, Ala124, Arg327, Tyr125, Tyr190, Tyr254, 1H NMR spectra were recorded either on a Perkin-Elmer EM-390
Asp270, Ile173, Ice110, Pro219, Arg228, Gly226, Asn51, Ser229, or on a Bruker WH-200 (400 MHz) in CDCl3 or DMSO-d6 as
Ser116 etc. being present in the active sites, and gives a clue solvent, using tetramethylsilane (TMS) as an internal standard
about the importance of hydrogen bond formation for effec- and chemical shis and coupling constants were expressed as
tive enzyme binding. For example, ligands (compounds) 5h d (ppm) and Hz respectively. Mass spectra were determined on
and 5l exhibit hydrogen bonds and other interactions (bonds) a Jeol SX 102/Da-600 mass spectrometer/Data System using
with amino acid residues Thr10, Leu44, Ile45, Leu46, Gly47, Argon/Xenon (6 kV, 10 mA0) as the FAB gas. The accelerating
Glu48, Gly49, Ser50, Asn51, Val52, Asn65, Ile110, Pro111, voltage was 10 KV and spectra were recorded at room temper-
Gly112, Cys113, Ser116, Ile119, Ile122, Gly12, Ala124, Tyr125, ature. Elemental analyses (CHN) were performed on a CHNS-O-
Tyr158, Arg159, Phe171, Ala172, Ile173, Tyr190, Arg214, analyser Flash EA 1112 series. The progress of the reaction was
Lys217, Leu218, Pro219, Lys222, Asn226, Ala227, Gly228, monitored using TLC on pre-coated silica gel G plates. All the
Ser229, Phe231, Lys232, Asn233, Pro252, Tyr254, Ala264, spectral data of the newly synthesized compounds were
Gly266, Trp267, Asp270, Lys275, Gln288, Ala289, Leu290, consistent with the proposed structures and microanalysis was
Glu325, and Arg327 which are present in the active site of E. within ꢂ 0.4 of the calculated values.
59384 | RSC Adv., 2016, 6, 59375–59388
This journal is © The Royal Society of Chemistry 2016

View Article Online
Paper
RSC Advances
2.35 (s, 3H, CH3 of 2,3-dichloro-5-triuoromethyl-6-methyl
phenyl), 8.4 (s, 2H, Ar-H of 2,3-dichloro-5-triuoromethyl-6-
methyl phenyl and 2,4-dinitro phenyl), 8.700–8.717 (d, 1H, J ¼
6.8 Hz, Ar-H of 2,4-dinitro phenyl), 8.940–8.957 (d, 1H, J ¼ 6.8
Hz, Ar-H of 2,4-dinitro phenyl), 9.42 (s, 1H, Ar-H of pyrazole),
10.64 (s, 1H, CHO of pyrazole). 13C NMR: (100 MHz, CDCl3):
4.2. General procedure for the synthesis of 3-{5-methyl-1-[2-
methyl-3-(triuoromethyl) phenyl/substituted phenyl]-1H-
1,2,3-triazol-4-yl}-1-(aryl)-1H-pyrazole-4-carbaldehyde (5a–n)
Vilsmeier–Haack reagent was prepared by adding phosphorous
oxychloride (3 mmol) drop-wise to DMF (10 ml) at 0 ꢁC and
stirring at the same temperature for 30 min under an inert
atmosphere. To this mixture, 4-{(1E)-1-[2-(aryl) hydrazinylidene]
ethyl}-5-methyl-1-[2-methyl-3-(triuoromethyl)phenyl/
substituted phenyl]-1H-1,2,3-triazole (1 mmol) (4a–n) was added
portion wise at 0 ꢁC, then the reaction mixture was heated to 60
ꢁC for 4–5 hours. The progress of the reaction was monitored
using TLC. Aer completion of the reaction, the reaction mass
was poured into crushed ice and water (80 ml). The reaction
mixture was then neutralized with 10% aqueous ammonia
solution, whereupon the solid product separated out and was
ltered, washed with an excess of cold water, dried and recrys-
tallized from ethanol to afford the pure product (5a–n).
4.2.1. 3-{1-[2,3-Dichloro-6-methyl-5-(triuoromethyl)
phenyl]-5-methyl-1H-1,2,3-triazol-4-yl}-1-phenyl-1H-pyrazole-4-
carbaldehyde (5a). IR (KBr) g/cmꢀ1: 3086 (Ar-H), 1671 (C]O),
1582 (C]N), 1185 (C–F) and 708 (C–Cl). 1H-NMR: (400 MHz,
CDCl3): d 2.19 (s, 3H, CH3 of triazole), 2.51 (s, 3H, CH3 of 2,3-
dichloro-5-triuoromethyl-6-methyl phenyl), 7.51–7.53 (t, 3H,
J ¼ 8.0 Hz, Ar-H of phenyl), 7.77–7.79 (d, 2H, J ¼ 8.0 Hz, Ar-H of
phenyl), 7.90 (s, 1H, Ar-H of 2,3-dichloro-6-triuoromethyl
phenyl), 8.60 (s, 1H, Ar-H of pyrazole), 10.82 (s, 1H, CHO of
pyrazole). 13C NMR: (100 MHz, CDCl3): d 9.62 (CH3 of triazole),
13.66 (CH3 of 2,3-dichloro-5-triuoromethyl-6-methyl phenyl),
120.62, 124.22, 127.05, 128.25, 128.33, 129.11, 129.88, 131.02,
131.13, 131.42, 133.65, 134.02, 135.17, 136.49, 137.54, 137.75,
146.65, 187.80 (CHO of pyrazole). MS: m/z ¼ 480.27 (M+), 482.27
(M+ + 2). Anal. calcd for C21H14Cl2F3N5O: calculated: C (52.52%),
H (2.94%), N (14.58%); found C (52.45%), H (2.92%), N
(14.52%).
d
8.74 (CH3 of triazole), 14.33 (CH3 of 2,3-dichloro-5-
triuoromethyl-6-methyl phenyl), 121.31, 124.04, 125.21,
125.34, 127.72, 129.66, 129.90, 129.96, 132.13, 132.19, 135.16,
135.48, 135.84, 136.04, 136.26, 137.11, 143.84, 146.56, 147.92,
187.31 (CHO of pyrazole). MS: m/z ¼ 570.1 (M+), 572.1 (M+ + 2).
Anal. calcd for C21H12Cl2F3N7O5: calculated: C (44.23%), H
(2.12%), N (17.91%); found C (44.12%), H (2.08%), N (17.82%).
4.2.4. 3-{1-[2,3-Dichloro-6-methyl-5-(triuoromethyl)
phenyl]-5-methyl-1H-1,2,3-triazol-4-yl}-1-(2,4,6-trichloro
phenyl)-1H-pyrazole-4-carbaldehyde (5d). IR (KBr) g/cmꢀ1: 3072
(Ar-H), 1665 (C]O), 1566 (C]N), 1169 (C–F) and 712 (C–Cl). 1H-
NMR: (400 MHz, DMSO-d6): d 2.12 (s, 3H, CH3 of triazole), 2.45
(s, 3H, CH3 of 2,3-dichloro-5-triuoromethyl-6-methyl phenyl),
7.44 (s, 2H, Ar-H of 2,4,6-trichloro phenyl), 7.66 (s, 1H, Ar-H of
2,3-dichloro-5-triuoromethyl-6-methyl phenyl), 8.50 (s, 1H, Ar-
H of pyrazole), 10.74 (s, 1H, CHO of pyrazole). 13C NMR: (100
MHz, CDCl3): d 6.78 (CH3 of triazole), 12.56 (CH3 of 2,3-
dichloro-5-triuoromethyl-6-methyl phenyl), 120.51, 123.41,
124.71, 125.10, 126.12, 128.48, 128.60, 129.12, 131.43, 131.69,
134.73, 135.11, 135.81, 136.02, 136.24, 136.91, 139.84, 142.46,
144.93, 187.21 (CHO of pyrazole). MS: m/z ¼ 583.2 (M+), 585.2
(M+ + 2). Anal. calcd for C21H11Cl5F3N5O: calculated: C (43.22%),
H (1.90%), N (12.00%); found C (43.25%), H (1.92%), N
(12.03%).
4.2.5. 3-{1-[2,3-Dichloro-6-methyl-5-(triuoromethyl)
phenyl]-5-methyl-1H-1,2,3-triazol-4-yl}-1-(phthalazin-1-yl)-1H-
pyrazole-4-carbaldehyde (5e). IR (KBr) g/cmꢀ1: 3069 (Ar-H), 1663
1
(C]O), 1565 (C]N), 1165 (C–F) and 709 (C–Cl). H-NMR: (400
MHz, DMSO-d6): d 2.02 (s, 3H, CH3 of triazole), 2.80 (s, 3H, CH3
of 2,3-dichloro-5-triuoromethyl-6-methyl phenyl), 7.20 (s, 2H,
Ar-H of 2,3-dichloro-5-triuoromethyl-6-methyl phenyl), 7.38–
7.53 (m, 4H, Ar-H of phthalazine), 7.70 (s, 1H, Ar-H of phtha-
lazine), 8.70 (s, 1H, Ar-H of pyrazole), 9.55 (s, 1H, CHO of pyr-
azole). 13C NMR: (100 MHz, CDCl3): d 6.56 (CH3 of triazole),
11.89 (CH3 of 2,3-dichloro-5-triuoromethyl-6-methyl phenyl),
112.20, 118.30, 127.51, 127.81, 128.21, 128.80, 129.72, 130.48,
131.10, 131.92, 132.43, 133.19, 133.93, 135.11, 135.81, 136.32,
137.24, 138.31, 141.9, 143.86, 151.91, 152.60, 190.11 (CHO of
pyrazole). MS: m/z ¼ 532.2 (M+), 534.2 (M+ + 2). Anal. calcd for
4.2.2. 1-(4-Chlorophenyl)-3-{1-[2,3-dichloro-6-methyl-5-(tri-
uoromethyl)phenyl]-5-methyl-1H-1,2,3-triazol-4-yl}-1H-
pyrazole-4-carbaldehyde (5b). IR (KBr) g/cmꢀ1: 3081 (Ar-H),
1678 (C]O), 1576 (C]N), 1181 (C–F) and 710 (C–Cl). 1H-
NMR: (400 MHz, CDCl3): d 2.12 (s, 3H, CH3 of triazole), 2.45
(s, 3H, CH3 of 2,3-dichloro-5-triuoromethyl-6-methyl phenyl),
7.44–7.46 (d, 2H, J ¼ 8.0 Hz, Ar-H of 4-chloro phenyl), 7.66–7.68
(d, 2H, J ¼ 8.0 Hz, Ar-H of 4-chloro phenyl), 7.84 (s, 1H, Ar-H of
2,3-dichloro-5-triuoromethyl-6-methyl phenyl), 8.50 (s, 1H, Ar-
H of pyrazole), 10.75 (s, 1H, CHO of pyrazole). 13C NMR: (100
MHz, CDCl3): d 9.61 (CH3 of triazole), 13.67 (CH3 of 2,3-
dichloro-5-triuoromethyl-6-methyl phenyl), 120.61, 124.23,
127.06, 128.24, 128.32, 129.10, 129.86, 131.04, 131.15, 131.44,
133.67, 134.05, 135.18, 136.49, 137.54, 137.75, 146.65, 187.84
(CHO of pyrazole). MS: m/z ¼ 514.7 (M+), 516.7 (M+ + 2). Anal.
calcd for C21H13Cl3F3N5O: calculated: C (49.00%), H (2.55%), N
(13.61%); found C (48.91%), H (2.52%), N (13.53%).
C
23H14Cl2F3N7O: calculated: C (51.90%), H (2.65%), N (18.42%);
found C (51.85%), H (2.62%), N (18.40%).
4.2.6. 3-{1-[2,3-Dichloro-6-methyl-5-(triuoromethyl)
phenyl]-5-methyl-1H-1,2,3-triazol-4-yl}-1-(8-trifuoromethyl qui-
nolin-4-yl)-1H-pyrazole-4-carbaldehyde (5f). IR (KBr) g/cmꢀ1
:
3074 (Ar-H), 1668 (C]O), 1568 (C]N), 1169 (C–F) and 715 (C–
Cl). 1H-NMR: (400 MHz, DMSO-d6): d 2.16 (s, 3H, CH3 of tri-
azole), 2.48 (s, 3H, CH3 of 2,3-dichloro-5-triuoromethyl-6-
methyl phenyl), 7.687–7.741 (t, 2H, J ¼ 10.8 Hz, Ar-H of 8-tri-
uoromethyl quinoline), 8.02 (s, 1H, Ar-H of 2,3-dichloro-5-
triuoromethyl-6-methyl phenyl), 8.220–8.231 (d, 1H, J ¼ 4.4
Hz, Ar-H of 8-triuoromethyl quinoline), 8.443–8.461 (d, 1H, J ¼
4.2.3. 3-{1-[2,3-Dichloro-6-methyl-5-(triuoromethyl)
phenyl]-5-methyl-1H-1,2,3-triazol-4-yl}-1-(2,4-dinitrophenyl)-
1H-pyrazole-4-carbaldehyde (5c). IR (KBr) g/cmꢀ1: 3071 (Ar-H),
1665 (C]O), 1568 (C]N), 1167 (C–F) and 711 (C–Cl). 1H-
NMR: (400 MHz, DMSO-d6): d 2.09 (s, 3H, CH3 of triazole),
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 59375–59388 | 59385

View Article Online
RSC Advances
Paper
7.2 Hz, Ar-H of 8-triuoromethyl quinoline), 8.60 (d, 1H, J ¼ 7.2 of pyrazole), 10.82 (s, 1H, CHO of pyrazole). 13C NMR: (100 MHz,
Hz, Ar-H of 8-triuoromethyl quinoline), 9.24 (s, 1H, Ar-H of CDCl3): d 9.63 (CH3 of triazole), 13.68 (CH3 of 2,3-dichloro-5-
pyrazole), 10.95 (s, 1H, CHO of pyrazole). 13C NMR: (100 MHz, triuoromethyl-6-methyl phenyl), 120.62, 124.22, 127.05,
CDCl3): d 8.15 (CH3 of triazole), 13.31 (CH3 of 2,3-dichloro-5- 128.25, 128.33, 129.11, 129.88, 131.02, 131.13, 131.42, 133.65,
triuoromethyl-6-methyl phenyl), 115.65, 120.29, 121.81, 134.02, 135.17, 136.49, 137.54, 137.75, 146.65, 187.80 (CHO of
123.46, 125.73, 126.64, 128.07, 128.13, 128.65, 128.85, 128.91, pyrazole). MS: m/z ¼ 446.10 (M+), 448.20 (M+ + 2). Anal. calcd for
128.97, 131.18, 133.14, 133.44, 134.57, 134.82, 135.24, 136.64,
C21H15ClF3N5O: calculated: C (56.57%), H (3.39%), N (15.71%);
142.44, 145.30, 146.27, 150.15, 186.65 (CHO of pyrazole). MS: m/ found C (56.48%), H (3.30%), N (15.62%).
z ¼ 599.2 (M+), 601.2 (M+ + 2). Anal. calcd for C25H14Cl2F6N6O:
4.2.10. 1-(2,4-Dinitrophenyl)-3-{5-methyl-1-[2-methyl-3-(tri-
calculated: C (50.10%), H (2.35%), N (14.02%); found C uoromethyl)phenyl]-1H-1,2,3-triazol-4-yl}-1H-pyrazole-4-
(50.02%), H (2.29%), N (13.92%).
4.2.7. 3-{1-[2,3-Dichloro-6-methyl-5-(triuoromethyl)
phenyl]-5-methyl-1H-1,2,3-triazol-4-yl}-1-(4-nitrophenyl)-1H-
carbaldehyde (5j). IR (KBr) g/cmꢀ1: 3072 (Ar-H), 1665 (C]O),
1567 (C]N), 1168 (C–F) and 702 (C–Cl). 1H-NMR: (400 MHz,
DMSO-d6): d 2.17 (s, 3H, CH3 of triazole), 2.37 (s, 3H, CH3 of 2-
pyrazole-4-carbaldehyde (5g). IR (KBr) g/cmꢀ1: 3070 (Ar-H), methyl-3-triuoromethyl phenyl), 7.502–7.546 (t, 2H, J ¼ 6.4 Hz,
1663 (C]O), 1566 (C]N), 1169 (C–F) and 710 (C–Cl). 1H- 11.2 Hz, Ar-H of 2-methyl-3-triuoromethyl phenyl), 7.90 (s, 2H,
NMR: (400 MHz, DMSO-d6): d 2.10 (s, 3H, CH3 of triazole), Ar-H of 2-methyl-3-triuoromethyl phenyl and 2,4-dinitro
2.36 (s, 3H, CH3 of 2,3-dichloro-5-triuoromethyl-6-methyl phenyl), 8.575–8.625 (t, 2H, J ¼ 7.6 Hz, 12.4 Hz, Ar-H of 2,4-
phenyl), 8.38 (s, 2H, Ar-H of 2,3-dichloro-5-triuoromethyl -6- dinitro phenyl), 8.73 (s, 1H, Ar-H of pyrazole), 10.86 (s, 1H, CHO
methyl phenyl and pyrazole), 8.696–8.713 (d, 2H, J ¼ 6.8 Hz, Ar- of pyrazole). 13C NMR: (100 MHz, CDCl3): d 8.71 (CH3 of tri-
H of 4-nitro phenyl), 8.937–8.954 (d, 2H, J ¼ 6.8 Hz, Ar-H of 4- azole), 14.32 (CH3 of 2-methyl-3-triuoromethyl phenyl), 121.28,
nitro phenyl), 10.63 (s, 1H, CHO of pyrazole). 13C NMR: (100 124.01, 125.11, 125.24, 127.63, 129.48, 129.83, 129.91, 132.09,
MHz, CDCl3): d 8.72 (CH3 of triazole), 14.31 (CH3 of 2,3- 132.15, 135.12, 135.39, 135.63, 136.01, 136.16, 137.05, 143.73,
dichloro-5-triuoromethyl-6-methyl phenyl), 121.28, 124.02, 146.45, 147.85, 187.20 (CHO of pyrazole). MS: m/z ¼ 502.2 (M+),
125.19, 125.31, 127.68, 129.63, 129.87, 129.92, 132.10, 132.15, 503.2 (M+ + 1). Anal. calcd for C21H14F3N7O5: calculated: C
135.13, 135.44, 135.80, 136.01, 136.22, 137.08, 143.81, 146.52, (50.31%), H (2.81%), N (19.56%); found C (50.40%), H (2.90%),
147.87, 187.28 (CHO of pyrazole). MS: m/z ¼ 525.1 (M+), 527.1 N (19.62%).
(M+ + 2). Anal. calcd for C21H13Cl2F3N6O3: calculated: C
4.2.11. 3-{5-Methyl-1-[2-methyl-3-(triuoromethyl)phenyl]-
(48.02%), H (2.49%), N (16.00%); found C (48.10%), H (2.52%), 1H-1,2,3-triazol-4-yl}-1-(2,4,6-trichlorophenyl)-1H-pyrazole-4-
N (16.08%).
4.2.8. 3-{5-Methyl-1-[2-methyl-3-(triuoromethyl)phenyl]-
carbaldehyde (5k). IR (KBr) g/cmꢀ1: 3072 (Ar-H), 1665 (C]O),
1566 (C]N), 1169 (C–F) and 712 (C–Cl). 1H-NMR: (400 MHz,
1H-1,2,3-triazol-4-yl}-1-phenyl-1H-pyrazole-4-carbaldehyde (5h). DMSO-d6): d 2.10 (s, 3H, CH3 of triazole), 2.41 (s, 3H, CH3 of 2-
IR (KBr) g/cmꢀ1: 3084 (Ar-H), 1669 (C]O), 1583 (C]N), 1187 methyl-3-triuoromethyl phenyl), 7.51 (s, 1H, Ar-H of 2,4,6-tri-
(C–F) and 709 (C–Cl). 1H-NMR: (400 MHz, CDCl3): d 2.20 (s, 3H, chloro phenyl), 7.54 (s, 1H, Ar-H of 2,4,6-trichloro phenyl),
CH3 of triazole), 2.54 (s, 3H, CH3 of 2-methyl-3-triuoromethyl 7.777–7.797 (d, 2H,
J
¼
8.0 Hz, Ar-H of 2-methyl-3-
phenyl), 7.389–7.426 (t, 1H, J ¼ 7.6 Hz, 7.2 Hz, Ar-H of triuoromethyl phenyl), 7.897–7.915 (d, 1H, J ¼ 7.2 Hz, Ar-H
phenyl), 7.511–7.551 (t, 4H, J ¼ 8.0 Hz, Ar-H of phenyl), 7.777– of 2-methyl-3-triuoromethyl phenyl), 8.50 (s, 1H, Ar-H of pyr-
7.797 (d, 2H, J ¼ 8.0 Hz, Ar-H of 2-methyl-3-triuoromethyl azole), 10.74 (s, 1H, CHO of pyrazole). 13C NMR: (100 MHz,
phenyl), 7.897–7.915 (d, 1H, J ¼ 7.2 Hz, Ar-H of 2-methyl-3- CDCl3): d 8.76 (CH3 of triazole), 12.52 (CH3 of 2-methyl-3-
triuoromethyl phenyl), 8.61 (s, 1H, Ar-H of pyrazole), 10.82 triuoromethyl phenyl), 120.42, 123.39, 124.61, 125.06, 126.09,
(s, 1H, CHO of pyrazole). 13C NMR: (100 MHz, CDCl3): d 9.60 128.39, 128.40, 129.07, 131.33, 131.61, 134.68, 135.09, 135.79,
(CH3 of triazole), 13.65 (CH3 of 2-methyl-3-triuoromethyl 136.02, 136.24, 136.87, 139.81, 142.42, 144.86, 187.20 (CHO of
phenyl), 120.62, 124.22, 127.05, 128.25, 128.33, 129.11, 129.88, pyrazole). MS: m/z ¼ 514.7 (M+), 516.7 (M+ + 2). Anal. calcd for
131.02, 131.13, 131.42, 133.65, 134.02, 135.17, 136.49, 137.54,
C21H13Cl3F3N5O: calculated: C (49.00%), H (2.55%), N (13.61%);
137.75, 146.65, 187.80 (CHO of pyrazole). MS: m/z ¼ 411.0 (M+), found C (49.07%), H (2.62%), N (13.70%).
412.0(M+ + 1). Anal. calcd for C21H16F3N5O: calculated: C
4.2.12. 3-{5-Methyl-1-[2-methyl-3-(triuoromethyl)phenyl]-
(61.31%), H (3.92%), N (17.02%); found C (61.22%), H (3.85%), 1H-1,2,3-triazol-4-yl}-1-(phthalazin-1-yl)-1H-pyrazole-4-
N (17.10%).
4.2.9. 1-(4-Chlorophenyl)-3-{5-methyl-1-[2-methyl-3-(tri-
uoromethyl)phenyl]-1H-1,2,3-triazol-4-yl}-1H-pyrazole-4-
carbaldehyde (5l). IR (KBr) g/cmꢀ1: 3068 (Ar-H), 1664 (C]O),
1565 (C]N), 1164 (C–F) and 712 (C–Cl). 1H-NMR: (400 MHz,
DMSO-d6): d 1.96 (s, 3H, CH3 of triazole), 2.99 (s, 3H, CH3 of 2-
carbaldehyde (5i). IR (KBr) g/cmꢀ1: 3082 (Ar-H), 1667 (C]O), methyl-3-triuoromethyl phenyl), 7.38–7.53 (m, 4H, Ar-H of 2-
1585 (C]N), 1185 (C–F) and 706 (C–Cl). 1H-NMR: (400 MHz, methyl-3-triuoromethyl phenyl and phthalazine), 7.70–7.83
CDCl3): d 2.21 (s, 3H, CH3 of triazole), 2.55 (s, 3H, CH3 of 2- (m, 4H, Ar-H of phthalazine), 8.68 (s, 1H, Ar-H of pyrazole), 9.55
methyl-3-triuoromethyl phenyl), 7.407–7.426 (d, 2H, J ¼ 7.6 (s, 1H, CHO of pyrazole). 13C NMR: (100 MHz, CDCl3): d 8.15
Hz, Ar-H of 4-chloro phenyl), 7.531–7.551 (d, 2H, J ¼ 8.0 Hz, Ar- (CH3 of triazole), 13.31 (CH3 of 2-methyl-3-triuoromethyl
H of 4-chloro phenyl), 7.777–7.797 (d, 2H, J ¼ 8.0 Hz, Ar-H of 2- phenyl), 115.74, 120.29, 121.81, 123.46, 125.73, 128.13, 128.65,
methyl-3-triuoromethyl phenyl), 7.897–7.915 (d, 1H, J ¼ 7.2 128.85, 128.91, 128.97, 131.18, 133.14, 133.44, 134.57, 134.82,
Hz, Ar-H of 2-methyl-3-triuoromethyl phenyl), 8.61 (s, 1H, Ar-H 135.24, 136.64, 142.44, 145.30, 146.27, 150.15, 186.68 (CHO of
59386 | RSC Adv., 2016, 6, 59375–59388
This journal is © The Royal Society of Chemistry 2016

View Article Online
Paper
RSC Advances
pyrazole). MS: m/z ¼ 463.4 (M+), 464.4 (M+ + 1). Anal. calcd for
Notes and references
23H16F3N7O: calculated: C (59.61%), H (3.48%), N (21.16%);
C
found C (59.55%), H (3.43%), N (21.12%).
4.2.13. 3-{5-Methyl-1-[2-methyl-3-(triuoromethyl)phenyl]-
1H-1,2,3-triazol-4-yl}-1-(8-trifuoromethyl
1 (a) H. Okusu, D. Ma and H. Nikaido, J. Bacteriol., 1996, 178,
306; (b) R. E. Isturiz, Int. J. Antimicrob. Agents, 2010, 36, S19.
2 (a) R. W. Sarver, J. M. Rogers and D. E. Epps, J. Biomol.
Screening, 2002, 7, 21; (b) M. S. Harris, J. T. Hergerg,
J. I. Cial-della, J. P. Martin Jr, T. E. Benson, G. H. Choi and
E. T. Baldwin, Acta Crystallogr., Sect. D: Biol. Crystallogr.,
2001, D57, 1032.
3 (a) T. Baba, T. Ara, M. Hasegawa, Y. Takai, Y. Okumura,
M. Baba, K. A. Datsenko, M. Tomita, B. L. Wanner and
H. Mori, Mol. Syst. Biol., 2006, 2, 0008, DOI: 10.1038/
msb4100050; (b) T. E. Benson, C. T. Walsh and V. Massey,
Biochemistry, 1997, 36, 796.
quinolin-4-yl)-1H-
pyrazole-4-carbaldehyde (5m). IR (KBr) g/cmꢀ1: 3072 (Ar-H),
1666 (C]O), 1565 (C]N), 1168 (C–F) and 708 (C–Cl). 1H-
NMR: (400 MHz, DMSO-d6): d 2.15 (s, 3H, CH3 of triazole),
2.47 (s, 3H, CH3 of 2-methyl-3-triuoromethyl phenyl), 7.687–
7.741 (t, 2H, J ¼ 10.8 Hz, Ar-H of 2-methyl-3-triuoromethyl),
8.02 (m, 2H, Ar-H of 2-methyl-3-triuoromethyl phenyl and
8-triuoromethyl quinoline), 8.220–8.231 (d, 1H, J ¼ 4.4 Hz,
Ar-H of 8-triuoromethyl quinoline), 8.443–8.461 (d, 1H, J ¼
7.2 Hz, Ar-H of 8-triuoromethyl quinoline), 8.591–8.609 (d,
2H, J ¼ 7.2 Hz, Ar-H of 8-triuoromethyl quinoline), 9.24 (s,
1H, Ar-H of pyrazole), 10.95 (s, 1H, CHO of pyrazole). 13C NMR:
(100 MHz, CDCl3): d 9.60 (CH3 of triazole), 15.45 (CH3 of 2-
methyl-3-triuoromethyl phenyl), 97.76, 115.74, 116.60,
123.74, 125.95, 126.70, 126.95, 127.10, 127.75, 128.14, 128.60,
128.71, 128.81, 131.03, 131.12, 131.40, 133.24, 134.09, 134.30,
145.03, 151.18, 187.78 (CHO of pyrazole). MS: m/z ¼ 530.4 (M+),
531.4 (M+ + 1). Anal. calcd for C25H16F6N6O: calculated: C
(56.61%), H (3.04%), N (15.84%); found C (56.52%), H (2.98%),
N (15.78%).
4 Y. Shen, J. Liu, G. Estiu, B. Isin, Y. Y. Ahn, D. S. Lee,
A. L. Barabasi, V. Kapatral, O. Wiest and Z. N. Oltavai, Proc.
Natl. Acad. Sci. U. S. A., 2010, 107, 1082.
5 (a) A. A. M. Abdel-Aziz, K. E. H. El-Tahir and Y. A. Asiri, Eur. J.
Med. Chem., 2011, 46, 1648; (b) M. A. El-Sayed, N. I. Abdul-
Aziz, A. A. Abdel-Aziz, A. S. El-Azab, Y. A. Asiri and K. E. El-
Tahir, Bioorg. Med. Chem., 2011, 19, 3416; (c) G. M. Morris,
R. Huey, W. Lindstrom, M. F. Sanner, R. K. Belew,
D. S. Goodsell and A. J. Olson, J. Comput. Chem., 2009, 30,
2785; (d) N. K. Sharma, K. K. Jha and J. K. K. Priyanka, J.
Adv. Sci. Res., 2010, 1, 67.
6 B. Halliwell and J. M. C. Gutteridge, Free Radicals in Biology
and Medicine, Oxford University Press, 3rd edn, 1999.
7 T. J. Montine, K. S. Montine, W. McMahan,
W. R. Markesbery, J. F. Quinn and J. D. Morrow, Antioxid.
Redox Signaling, 2005, 7, 269.
4.2.14. 3-{5-Methyl-1-[2-methyl-3-(triuoromethyl)phenyl]-
1H-1,2,3-triazol-4-yl}-1-(4-nitrophenyl)-1H-pyrazole-4-
carbaldehyde (5n). IR (KBr) g/cmꢀ1: 3072 (Ar-H), 1665 (C]O),
1568 (C]N), 1171 (C–F) and 705 (C–Cl). 1H-NMR: (400 MHz,
DMSO-d6): d 2.16 (s, 3H, CH3 of triazole), 2.36 (s, 3H, CH3 of 2-
methyl-3-triuoromethyl phenyl), 7.502–7.546 (t, 2H, J ¼ 6.4 Hz,
11.2 Hz, Ar-H of 2-methyl-3-triuoromethyl phenyl), 7.882–
7.900 (d, 3H, J ¼ 7.2 Hz, Ar-H of 2-methyl-3-triuoromethyl
phenyl and 4-nitro phenyl), 8.575–8.594 (d, 2H, J ¼ 7.6 Hz, Ar-
H of 4-nitro phenyl), 8.73 (s, 1H, Ar-H of pyrazole), 10.86 (s,
1H, CHO of pyrazole). 13C NMR: (100 MHz, CDCl3): d 8.71 (CH3
of triazole), 14.30 (CH3 of 2-methyl-3-triuoromethyl phenyl),
121.25, 124.01, 125.14, 125.28, 127.63, 129.60, 129.82, 129.88,
132.07, 132.07, 135.08, 135.36, 135.76, 136.01, 136.17, 137.05,
143.71, 146.45, 147.81, 187.20 (CHO of pyrazole). MS: m/z ¼
456.1 (M+), 457.1 (M+ + 1). Anal. calcd for C21H15F3N6O3:
calculated: C (55.27%), H (3.31%), N (18.41%); found C
(55.35%), H (3.30%), N (18.38%).
8 J. A. Berliner and J. W. Heinecke, Free Radical Biol. Med.,
1996, 20, 707.
9 Z.-J. Wang, Y. Gao, Y.-L. Hou, C. Zhang, S.-J. Yu, Q. Bian,
Z.-M. Li and W.-G. Zhao, Eur. J. Med. Chem., 2014, 86, 87–94.
10 P. Rahul Jadhav, N. Hemant Raundal, A. Amar Patil and
D. Vivek Bobade, J. Saudi Chem. Soc., 2015, DOI: 10.1016/
j.jscs.2015.03.003.
11 M. G. Perrone, P. Vitale, A. Panella, C. G. Fortuna and
A. Scilimati, Eur. J. Med. Chem., 2015, 94, 252–264.
12 N. Naik, J. Ramprasad, U. Dalimba, P. Yogeeshwari,
D. Sriram, H. S. Santosh Kumar, S. K. Peethamber and
R. Achur, Res. Chem. Intermed., 2016, 42(4), 3721–3741.
13 D. Gonzaga, M. Roberto Senger, F. d. C. da Silva, V. Francisco
Ferreira Floriano and P. Silva, Eur. J. Med. Chem., 2014, 74,
461–476.
Acknowledgements
14 R. Pingaew, A. Saekee, P. Mandi, C. Nantasenamat,
S. Prachayasittikul, S. Ruchirawat and V. Prachayasittikul,
Eur. J. Med. Chem., 2014, 84, 65–76.
One of the authors, Manjunatha Bhat, is grateful to the
management of SeQuent Scientic Ltd., New Mangalore,
India for supporting research work. Manjunatha Bhat is also
thankful to the late Prof. A. Srikrishna, Department of
Organic Chemistry, IISc, Bangalore and MIT, Manipal for
providing 1H NMR and 13C NMR spectral facilities. We are
also thankful to the Dept. of Biochemistry, Jnanasahyadri,
Kuvempu University, Shankarghatta, Karnataka for providing
kind help with the biological activity studies. The authors are
also thankful to the Chairman, Dept. of Chemistry, Mangalore
University.
15 H. Mubarak Shaikh, D. Dnyaneshwar Subhedar, A. Firoz
Kalam Khan, N. Jaiprakash Sangshetti and B. Bapurao
Shingate, Chin. Chem. Lett., 2016, 27(2), 295–301.
16 I. Khan, K. Santosh Guru, K. Santosh Rath, K. Praveen
Chinthakindi, B. Singh, S. Koul, S. Bhushan and L. Payare
Sangwan, Eur. J. Med. Chem., 2016, 108, 104–116.
17 N. Harikrishna, A. M. Isloor, K. Ananda, A. Obaid and
H.-K. Fun, RSC Adv., 2015, 5, 43648–43659.
This journal is © The Royal Society of Chemistry 2016
RSC Adv., 2016, 6, 59375–59388 | 59387

View Article Online
RSC Advances
Paper
18 S. Viveka, Dinesha, P. Shama, G. K. Nagaraja, S. Ballav and 25 (a) A. prakash, J. Agric. Food Chem., 2001, 44, 701–705; (b)
S. Kerkar, Eur. J. Med. Chem., 2015, 101, 442–451.
19 R. Gondru, J. Banothu, R. K. Thatipamula, S. K. Althaf
J. A. Vinson, Y. Hao, X. Su and L. Zubik, J. Agric. Food
Chem., 1998, 46, 3630–3634.
Hussain and R. Bavantula, RSC Adv., 2015, 5, 33562–33569. 26 D. Mengin-Lecreulx, B. Flouret and J. van Heijenoort, J.
20 S. Viveka, Dinesha, P. Shama, S. Naveen, N. K. Lokanath and
G. K. Nagaraja, RSC Adv., 2015, 5, 94786–94795.
21 Dinesha, S. Viveka, B. Keerthi Priya, K. S. Ranganath Pai,
S. Naveen, N. K. Lokanath and G. K. Nagaraja, Eur. J. Med.
Chem., 2015, 104, 25–32.
Bacteriol., 1982, 151, 1109.
27 A. R. Beth, Y. Youjun, S. Anatoly, R. Chopra,
G. Krishnamurthy, G. Singh, W. Hu, D. Keeney,
K. Petersen, J. Peter, P. Labthavikul, D. M. Shlaes,
A. A. Failli, J. S. Shumsky, M. Kristina, K. Kutterer,
A. Gilbert and T. S. Mansour, J. Antimicrob. Chemother.,
2006, 50, 556.
22 B. A. Arthington-Skaggs, D. W. Warnock and C. J. Morrison,
J. Antimicrob. Chemother., 2000, 44(8), 2081–2085.
23 I. Kubo, K. I. Fujita, A. Kubo, K. I. Nihel and T. Ogura, J. Agric. 28 M. B. Sapkal and H. D. More, Der Pharma Chemica, 2013,
Food Chem., 2004, 52, 3329–3332.
5(6), 164–172.
24 D. J. Mac Lowry, M. J. Jaqua and S. T. Selepak, Appl.
Microbiol., 1970, 20, 46–53.
59388 | RSC Adv., 2016, 6, 59375–59388
This journal is © The Royal Society of Chemistry 2016