Design and synthesis of triazole conjugated novel 2,5-diaryl substituted 1,3,4-oxadiazoles as potential antimicrobial and anti-fungal agents

Article abstract of DOI:10.1016/j.molstruc.2020.128705

A series of triazole conjugated novel 2,5-diaryl 1,3,4-oxadiazole derivatives 8a-q are efficiently synthesized starting from methyl salicylate. All the synthesized compounds were characterized based on their ¹H NMR, ¹³C NMR, Mass and

Full text of DOI:10.1016/j.molstruc.2020.128705

Journal Pre-proof
Design and synthesis of triazole conjugated novel 2,5-diaryl substituted 1,3,4-
oxadiazoles as potential antimicrobial and anti-fungal agents
Sampath Bitla, Someswar Rao Sagurthi, Ramulu Dhanavath, Puchakayala Muralidhar
Reddy, Saritha Birudaraju, Akkiraju Anjini Gayatri, Bhukya Vijaya Kumar, Krisham
Raju Atcha
PII:
S0022-2860(20)31030-9
DOI:
https://doi.org/10.1016/j.molstruc.2020.128705
MOLSTR 128705
Reference:
To appear in: Journal of Molecular Structure
Received Date: 6 January 2020
Revised Date: 11 June 2020
Accepted Date: 12 June 2020
Please cite this article as: S. Bitla, S.R. Sagurthi, R. Dhanavath, P.M. Reddy, S. Birudaraju, A.A. Gayatri,
B.V. Kumar, K.R. Atcha, Design and synthesis of triazole conjugated novel 2,5-diaryl substituted 1,3,4-
oxadiazoles as potential antimicrobial and anti-fungal agents, Journal of Molecular Structure (2020), doi:
https://doi.org/10.1016/j.molstruc.2020.128705.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition
of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of
record. This version will undergo additional copyediting, typesetting and review before it is published
in its final form, but we are providing this version to give early visibility of the article. Please note that,
during the production process, errors may be discovered which could affect the content, and all legal
disclaimers that apply to the journal pertain.
©
2020 Published by Elsevier B.V.

Author contribution
KRA, SB, SSR conceived the idea and provided critical inputs to the concept. KRA planed the
experiment, SB and RD. generated synthesis data. Molecular docking and Biological assays are
carried out by SSR and AAG. All the authors KRA,SB,SSR, RD, PMR, SB2, AAG and BVK
contributed to analyze, interpret data and wrote the manuscript. All authors contributed to the
final reading and approved the submitted revised version.

Design and Synthesis of Triazole Conjugated Novel 2,5-Diaryl Substituted
,3,4-Oxadiazoles as Potential Antimicrobial and Anti-fungal Agents
1
a
b
a
Sampath Bitla , Someswar Rao Sagurthi , Ramulu Dhanavath , Puchakayala Muralidhar
a
a
b
a
Reddy , Saritha Birudaraju , Akkiraju Anjini Gayatri , Bhukya Vijaya Kumar , Krisham
a*
Raju Atcha
a
Department of Chemistry, Nizam College, Osmania University, Hyderabad, Telangana-500007, India
b
Molecular Medicine Lab, Department of Genetics & Biotechnology, Osmania University, Hyderabad,
Telangana-500007, India
Corresponding author Email: krishnamrajua@osmania.ac.in
Abstract: A series of triazole conjugated novel 2,5-diaryl 1,3,4-oxadiazole derivatives 8a-q are
efficiently synthesized starting from methyl salicylate. All the synthesized compounds were
1
13
characterized based on their H NMR, C NMR, Mass and IR data. All the compounds have
been investigated for antibacterial activity against Staphylococcus aureus, Escherichia coli and
Bacillus subtilis and antifungal activity against Aspergillus niger and Saccharomyces cerevisiae.
It is interesting to note that all compounds 8a-q were found to be effective, potent and active
against microbial growth when compared with standard antibacterial agents. Our findings
suggest that compounds 8d-f, 8l and 8o are the major ones shown anti-fungal activity among all
the synthesized compounds. From our results, it is found that all the compounds 8a-q have
exhibited no appreciable potency towards clearing the free radicals in solution. Molecular
docking studies of the synthesized compounds with penicillin-binding proteins (PDB ID: 3HUN
and 3ITA) are in good agreement with their inhibition activity. The compounds 8p and 8q were
found to be effective against microbial growth in gram-positive bacteria, whereas in gram-
negative bacteria compound 8d shown good synergy with biological assays and docking studies.
These novel series of compounds have shown promising features in inhibiting the
microorganisms by interacting with enzymes involved in peptidoglycan synthesis and bacterial
cell wall biosynthesis.
Keywords: 1,3,4-Oxadiazole, 1,2,3-triazole, anti-bacterial activity, anti-fungal activity.
1
. Introduction:
Microbial infection is one of the major areas of concern in healthcare and community
environments as it remains a global threat. The United Nations adhoc Interagency Coordination
Group (IACG) on Antimicrobial Resistance has recently reported an estimate of 10 million
deaths each year by 2050 due to drug-resistant microbial diseases. It could force up to 24 million
people into extreme poverty by 2030 [1]. Effective antimicrobial drugs are prerequisites for both
preventive and curative measures, protecting patients from potentially fatal diseases and ensuring
that complex procedures, such as surgery and chemotherapy, can be provided at low risk [2]. A
particular concern was severe infections caused by Gram-positive bacteria Staphylococcus

aureus [3], Bacillus subtilis [4] and Gram negative bacteria Escherichia coli [5]. The mode of
action of β-lactam antibiotics found to have similar in their sugar–amino acid backbone
structures and involved in peptidoglycan formation. In due course of time, it has become eminent
that β-lactam antibiotics became ineffective. Thus, raise in microbial antibiotic resistance is
necessary to avoid or to treat the current infections. 1,3, 4- Oxadiazoles, a novel class of non-β
lactam antibiotics might fight against bacteria in a way different to β-lactam penicillins.
Nitrogen and oxygen-containing heterocyclic ring compounds have gained significant
importance globally not only due to their prevalence in natural products but also due to their
pharmacological, photochemical optoelectronic properties and industrial value [6-12]. 1,3,4-
Oxadiazoles and its derivatives became interesting over the past few years and found wide
applications in pharmaceuticals, dyes, photographic materials, agrochemicals and corrosion
inhibition [13-14]. Most importantly, the isomeric arrangement of heteroatoms and other five-
membered rings like triazoles, pyrazoles, and isoxazoles were potent in reporting antibacterial
activity [15]. The oxadiazoles are privileged scaffolds found in diverse areas such as medicinal,
pesticidal, polymer and material science [16]. A number of compounds containing an oxadiazole
moiety possess broad-spectrum bioactivities like antibiotic [17-19], anticancer [20-22], and anti-
hypertensive [23-25]. Significant efficacy of 1,3,4-oxadiazoles have also been demonstrated for
past few years in various pharmacological properties including anti-microbial [26-30], anti-
inflammatory, analgesic [31-32], anti-HIV [33-35], anti-mycobacterial [36], inhibitors of
Cathepsin K [37], inhibitors of tyrosinage [38-40], anti-convulsant [41-43], and muscle-relaxant
[44]. On the other side, raltegravir, an antiretroviral drug for the treatment of HIV infection, has
been launched into the market (Fig-1) [17,25,45-46]. In addition to their latent potential in
medicinal chemistry, the oxadiazoles also find application in the field of material science where
butyl-PBD or b-PBD is used in the liquid scintillator neutrino detector [47]. Hence diverse
ranges of oxadiazoles applications have attracted the scientific community to develop novel
oxadiazoles, which have an enormous impact on multiple drug discovery processes.

On the other hand, 1,2,3-triazole’s is a versatile moiety which is continuously attracting the
attention of medicinal chemists due to its synthetic feasibility and numerous biological activities
(Fig-2) when combined with other heterocyclic moieties [48-52].
As part of on-going research in our lab, encouraged by the above finding towards the
development of novel antimicrobial and anti-fungal agents with improved therapeutic efficacy
and stimulated by the biological significance of triazole containing 1,3,4-oxadiazoles [53],
herein, we have described the design and synthesis of a series of 1,2,3-triazole conjugated with
2
,5-diaryl substituted 1,3,4-oxadiazoles. All the synthesized compounds were thoroughly
1
3
characterized based on their Proton NMR, C NMR, Mass and IR spectral data. All the
synthesized 8a-q compounds are investigated for their antimicrobial, anti-fungal and anti-oxidant
activities.
2
2
. Results and Discussion:
.1. Chemistry
The synthetic approach followed in achieving the designed target oxadiazoles 8a-q is
summarized in Scheme 1. The synthesis was initiated with the propargylation on methyl
salicylate 1 using propargyl bromide in the presence of potassium carbonate base and dry
dimethyl formamide solvent to afford compound 2 in 85% yield. The spectral data of alkyne 2 is
in agreement with the reported data [54]. The selective synthesis of required triazoles 4a-d was
efficiently achieved by using copper (I) catalyzed [CuAAC] Huisgene 1,3-dipolar cyclo addition
of alkyne 2 with azides 3a-d in good yields. The formation of triazole 4a was confirmed by its
1
spectral data where the H NMR spectrum of 4a showed characteristic triazole proton absorption
at δ 8.02 as a singlet, O-CH
appeared at 3.89 as a singlet, it is further confirmed by its Mass spectral data which has given
M+1) peak atm/z 344. The obtained triazoles 4a-d are then treated with hydrazine hydrate using
,4-dioxane as a solvent to afford the benzohydrazides 5a-d in quantitative yields. The
2 3
- absorption appeared as a singlet at δ 5.40, ester -OCH signal
(
1
1
disappearance of -OCH singlet peak form δ 3.89 in the H NMR and appearance of two new
3
signals at δ 4.53 (a singlet for two protons) and δ 9.21 (a singlet for one proton) due to -NH and
2

-NH respectively confirmed the structure of compound 5a. Further, Mass spectral data is in
agreement with its molecular formula. The condensation reaction between benzohydrazides 5a-d
and different substituted benzaldehydes 6a-g was afforded the Schiff’s base products 7a-q,
which without any further purification were subjected to intramolecular cyclization under
PhI(OAc) in ethanol solvent conditions to yield the final target 1,2,3-triazole conjugated 2,5-
2
diaryl substituted 1,3,4-oxadiazoles 8a-q in good yields.
All the synthesized final compounds 8a-8q were analyzed by their respective spectral data. The
-1
IR spectrum of compounds 8a exhibited its characteristic C=N absorption band at 1595 cm .
1
The single triazole proton of compound 8a appeared as a singlet at δ 8.36 in its H NMR, and a
1
3
singlet corresponding to two –OCH protons appeared at δ 5.49. Further, the C NMR spectrum
2
of compound 8a given the absorption of –OCH carbon at δ 63.3. Mass spectral data of
2

3 5 2
compound 8a has given the M+1 peak at m/z 481 (M.F: C23H14Cl N O ) which is in agreement
with its calculated mass.
2
2
.2. Biology
.2.1. Antibacterial activity
The synthesized final compounds 8a-q were evaluated for antibacterial activity in vitro. To
assess the antimicrobial properties of synthesized compounds, two strains of Gram-positive
bacteria (Bacillus subtilis MTCC 441, Staphylococcus aureus MTCC 96) and one strain of
Gram-negative bacteria (Escherichia coli MTCC 443) were chosen based on their capability of
raising resistance to develop drugs [55]. A specific concentration of compound where the
bacterial growth inhibition has started is termed as a minimal concentration of compound
required for bacterial inhibition. Based on the study of tested antibacterial activities against
different strains [56-57], it is noted that all compounds 8a-q were found to be very effective,
potent and active against microbial growth when compared with standard antibacterial agents
(Table -1) & (Fig -3). These series of compounds have shown promising features in inhibiting
the microorganism by interaction with enzymes involved in peptidoglycan synthesis and
bacterial cell wall biosynthesis. The compounds 8p & 8q have shown good inhibition in gram
positive bacteria whereas 8p not able to inhibit the gram-negative bacteria. Compound 8d
inhibited best against the gram negative bacteria, it might be having better mode of binding than
the 8p. In overall all the compounds shown good antimicrobial activity except few compounds in
gram negative bacteria (8f, 8h, 8o, and 8p). The strain of E. coli might have bestowed with
alternative pathway and not shown good inhibition activity.
Table-1:
Antibacterial activity: Minimum inhibitory concentration (MIC) of the synthesized compounds
(μg/ml) against gram-positive and gram-negative bacterial strains
Gram positive bacteria
Compound No.
Gram negative bacteria
S. aureus
B.subtilis
E. coli
MTCC 96
MTCC 441
MTCC 443
8
a
9.9
8.8
8.9
8.4
8.7
5
9
8
b
6
10
8
c
5.6
5.5
5.6
8.5
4.8
9.8
8
d
8
e

8
f
8.7
9.8
8.4
9
5.4
6
>50
10
8
g
8
h
5.8
5.7
5
>50
9.7
8.2
10
8
i
8
j
8.9
8.6
8.5
8.6
9.7
8.9
8.8
7.9
10
8
k
5.4
5
8
l
25
8
m
5.9
5.8
5.4
5.7
5.5
10
9.8
10
8
n
8
o
p
q
>50
>50
9
8
8
Ampicillin
4
Anti-bacterial activity of Triazole Conjugated Novel 2,5-Diaryl Substituted 1,3,4-Oxadiazoles in
micro dilution method:
3
2
2
1
1
0
5
0
5
0
5
0
S. aureus MTCC 96
B.subtilis MTCC 441
E. coli MTCC 443
Fig -3. Graphical representation of antibacterial activity in bar diagram.

2
.2.2. Anti-fungal activity
The anti-fungal activities of the synthesized 8a-q compounds were tested against filamentous
fungi Aspergillus niger MTCC 404 and Saccharomyces cerevisiae MTCC 1344 yeast cultures
[
58]. Our findings suggested that 8d, 8e, 8f, 8g, 8l and 8o are the compounds showed potent anti-
fungal activity among all other synthesized triazole conjugated 1,3,4-oxadiazole compounds
Table -2).
(
o
Table – 2: Zone of fungal growth inhibition (mm) after incubating for 2 days at 37 C.
Aspergillus niger MTCC 404
Saccharomyces cerevisiae MTCC 1344
Compound
no.
Compound concentration (μM)
8
a
b
2 (10)
2 (10.8)
2 (10.2)
3 (20)
23. (21.7)
2 (20.4)
3 (30)
2 (10)
2 (10.8)
3 (10.2)
2 (20)
2.5 (21.7)
3 (20.4)
3.2 (30)
2.6 (32.6)
3.5 (30.6)
8
2.5 (32.6)
2.3 (30.6)
8
c
8
d
e
5.2 (10.7)
5.2 (11.6)
6 (21.5)
6 (23.2)
6 (32.3)
6.2 (34.8)
3 (10.7)
4 (11.6)
3.3 (21.5)
5 (23.2)
4 (32.3)
5.3 (34.8)
8
8
f
7.2 (12.6)
6 (12.6)
2 (11.7)
3 (10.9)
8 (25.2)
7 (25.2)
8.2 (37.8)
7 (37.8)
3 (12.6)
5 (12.6)
1 (11.7)
3.3 (10.9)
3 (25.2)
5.4 (25.2)
1.5 (23.4)
3.6 (21.9)
5 (37.8)
6 (37.8)
2 (35.2)
4 (32.8)
8
8
g
h
2.4 (23.4)
3.3 (21.9)
2.7 (35.2)
3.5 (32.8)
8
i
j
8
3 (10.7)
4 (11.60
4.6 (12.1)
3 (12)
3.2 (21.5)
4 (23.2)
3.3 (32.3)
4.2 (34.8)
5.3 (36.5)
3.5 (36.2)
4 (10.7)
2 (11.6)
5 (12.1)
2.4 (12)
4.2 (21.5)
2.2 (23.2)
6 (24.3)
4.6 (32.3)
2.4 (34.8)
6.2 (36.5)
3.5 (36.2)
8
k
8
l
5 (24.3)
8
m
3.2 (24.1)
2.8 (24.1)
8
n
o
p
q
3.7 (11.6)
6 (10)
4 (23.2)
7.2 (20)
4.2 (20.5)
3.5 (20.2)
10 (24)
4 (34.8)
7.6 (30)
4.2 (30.8)
3.7 (30.3)
12 (36)
4 (11.6)
3.5 (10)
2 (10.2)
3 (10.1)
8 (12)
4.6 (23.2)
4.5 (20)
2.2 (20.5)
4 (20.2)
9 (24)
5 (34.8)
5.5 (30)
3 (30.8)
5 (30.3)
12 (36)
8
8
8
4 (10.2)
3 (10.1)
8 (12)
Miconazole
Anti-fungal activity of Triazole Conjugated Novel 2,5-Diaryl Substituted 1,3,4-Oxadiazoles
against Aspergillus Niger MTCC 404 and Saccharomyces cerevisiae MTCC 1344 by cross
streak plate method.

2
.2.3. Anti-oxidant activity
DPPH radical scavenging assay revealed that, all 8a-q Oxadiazole derivatives exhibited minor
potency towards clearing the free radicals in solution (Table-3) (Fig- 4).
Table – 3: % Antioxidant activity of Triazole Conjugated Novel 2,5-Diaryl Substituted 1,3,4-
Oxadiazole compound at various concentrations.
Compound concentration (µM)
Compound No.
1
44.1
-2.1
0
50
44.5
4.3
100
45.8
20.9
-1.8
-46.5
23.2
26.4
-13.2
0.8
200
79.3
30.3
7.5
Ascorbic acid
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
a
b
c
-20.6
-89.3
-3.7
-6.9
-70.5
1.5
8.4
d
e
f
39.4
37
-0.5
23.4
41.9
1.5
-1.2
14.1
-17.1
0.2
-38.5
-18
g
h
i
-83.1
-38
-38.1
-10.1
-18.5
-29.3
-10.8
-0.9
-36.5
-1.2
-13.9
-26
j
k
l
m
n
o
p
q
-40.3
-62.5
-13
-0.2
1
3.9
3.6
6.1
-0.2
15.6
14.9
20.1
-3.9
20.3
1.1
3.9
5.8
-86.3
-53.7
-17.8
-15.6
25.5
-4.8
-1.1
-21.7
16.5

1
00
8
6
4
2
0
0
0
0
0
1
5
1
2
0 µM
0 µM
00 µM
00 µM
-
-
-
-
20
40
60
80
-
100
Compound concentration(µM)
Fig-4. Graphical bar diagram representation of percent antioxidant activity of 8a-8q synthesized
compounds
.
2
.2.4. In silico Molecular Docking Studies:
Synthesized ligands were screened insilico for potent antimicrobial agents using Molegro Virtual
Docker (MVD). It is well known that the β-lactam antibiotics often target more than one (PBP)
Penicillin binding protein during bacterial inhibition due to several closely related PBP’s. As the
β-lactam antibiotics found to be similar in their sugar–amino acid backbone structures, the
following cell wall biosynthesis mechanism treats these antibiotics as own and forms the
peptidoglycan layers. In a deal with this successful aspect the present study focused on synthesis
of non-β-lactam derivatives called oxadiazoles, which would likely target multiple PBP’s in
various strains combating drug resistance. The principles from electronic properties, geometry
suggest that the electrostatic interaction plays a pivotal role in attraction between compound
aromatic chain and amino acid residues [59]. In addition to this, it is well known that the
arrangement of heteroatoms and five-membered rings like triazoles and pyrazoles were potent in
antibacterial activity with nitrogen and oxygen atoms in their aromatic rings. We have selected
two co-crystal structure of two different PBPs (PDB ID: 3HUN; PBP4) and (3ITA; PBP6) from
S. aureus (Gram positive) and E. coli (Gram negative), respectively. Both the structures were
determined with ampicillin in their active site with high resolution of 2 Å [60] from S. aureus
where as an E. coli structure with the 1.85 Å [61]. The oxadiazole derivatives were subjected to
in silico docking against 3HUN and 3ITA to predict their ability and mode of binding. Best dock
score depicts the interactions of protein-ligand complexes, thus, revealing the synthesized

compounds’ ability to bind to spectrum of PBP4 and PBP6. The compounds 8p and 8q with high
moldock score showed maximum number of pi-bond interactions at specific amino acid residues
present in the binding pocket. Pi-alkyl, pi-sigma, pi-pi interactions along with other hydrogen
interactions prevalent in protein crystal structures contribute to the microbial growth
susceptibility. All the 17 ligands synthesized have shown good docking scores with strong
binding affinities towards PBPs (Table -4). The active site of PBP4 (PDB id: 3HUN) & 3ITA
identified from the earlier studies as well confirmed with the Protein ligand server:
"
https://projects.biotec.tu-dresden.de/plip-web/plip/index". The crystal structure of 3HUN is
bound with ampicillin as inhibitor by having hydrogen bonding with Ser 75, Ser116 Ser 386
hydrophobic interaction with Phe 241 and water bridges with Lys 78, Ser 116 and Ser 262 [60].
Our docking also showed binding of 8p and 8q molecules in the same active site vicinity with
Ser 75 (2.75 Å) and Tyr 291 (2.57 Å); Ser 75 (2.23 Å) and Ser 116 (1.98 Å) respectively via
hydrogen bonding (Fig-5). Similarly, 3ITA docking results confirmed the same with higher
docking scores for 8p and 8q. The co-crystal ampicillin also made few hydrogen bonding
interactions with active site residues consisting of Ser 40 (2.92 Å), Thr 210 (3.68 Å) and Thr 212
(
2.92 Å) [61]. Our docking results with synthesized compounds had shown similar interactions
which were found in co-crystal structures. The compounds had shown hydrogen bonding Ser 40
2.95 Å) Arg 244 (2.46 Å) in 8, where as in 8q, Thr 212 (1.91 Å) and Arg 194 (2.5 Å) as well
(
both inhibitors were stabilized by hydrophobic and pi-pi interactions (Fig-6). The superposition
of 3HUN and 3ITA co-crystal structures with the docked 8p-8q structures confirmed the
orientation and mode of binding (Fig-7) all of them were well aligned within the active site
vicinity. The docking was executed with PBP6 (3ITA) protein as target whereas inhibition assay
was carried out in living E. coli. In spite of good docking score, the compound 8p displayed
turbid growth when treated with a concentration of >50 µg/ml in vitro revealing that E. coli
might be bestowed with a complementing system or an alternative pathway to overcome the
inhibition by 8p compound. On the other hand docking score of compound 8d in the same series
was in accord with in vitro inhibition values. Docking scores and biological assays of 8p and 8q
had shown synergy in gram positive bacteria.

Table - 4: In silico Molecular Docking of synthesized compounds against PBP4 (PDB ID:
3
HUN) and PBP6 (PDB ID: 3ITA).
Mol Dock
Mol Dock
Score
Rerank
Score
Rerank score
3HUN)
Ligand
Score
(
(3HUN)
(3ITA)
-155.31
-151.87
-152.62
-149.76
-148.13
-154.78
-141.03
-146.15
-157.07
-141.03
-151.94
-147.69
-148.52
-143.56
-159.84
-163.56
-165.83
(3ITA)
-109.27
-116.13
-115.67
-108.12
-103.93
-99.95
8
a
-158.68
-155.23
-157.46
-149.78
-150.34
-154.27
-146.57
-146.62
-157.83
-164.57
-151.14
-148.20
-147.28
-151.04
-145.58
-162.38
-165.92
-101.37
-106.50
-111.63
-106.67
-85.071
-105.51
-90.25
8
b
8c
8
d
8e
8f
8
g
-102.11
-18.42
-108.47
-94.48
8
h
-106.72
-107.13
-112.85
-101.03
-104.89
-90.73
8i
8j
8
k
-99.95
8l
-80.97
8
m
-119.01
-89.35
8
n
-98.16
8
o
p
q
-82.91
-115.12
-113.62
-118.59
-124.70
-111.42
8
8
3
. Conclusion:
In this study, we have designed and synthesized a series of triazole conjugated novel 2, 5-diaryl
substituted 1,3,4-oxadizole derivatives 8a-q. These Oxadiazoles are valuable five-membered
aromatic heterocycles bestowed with a wide range of biological inhibiting activities including
antibacterial, anti-fungal and antiparasitic. All the compounds 8a-q were investigated for their
antimicrobial, anti-fungal and antioxidant activities. It is noted that all compounds 8a-q were
found to be effective, potent and active against microbial growth when compared with standard
antibacterial agents. All the compounds were found in completely inhibiting the microbial
growth by binding efficiently to proteins of bacterial cell wall biosynthesis. Our findings
suggested that among all other synthesized triazole conjugated 1,3,4-oxadiazole compounds 8p
and 8q are the best compounds showing anti-fungal as well as antimicrobial activity. Based on
the DPPH radical scavenging assay it was observed that all derivatives (8a-q) displayed a minor
potency towards clearing the free radicals in solution. The best dock scored compounds from our
current in silico study were further confirmed with the minimal microbial growth. The
compounds 8p and 8q were effective against gram positive bacteria, and 8d had shown
promising features against gram negative bacteria.

4
4
. Experimental:
.1. Chemistry
General Remarks:
All solvents, chemicals, reagents were purchased in LR grade from the commercial vendors
Merck, Sigma-Aldrich and Avra chemicals and used as such in the reactions. NMR spectra was
recorded on Bruker Avance-II 400 MHz instrument, TMS is used as an internal reference
6
standard and CDCl
3
/d -DMSO used as solvents.Aluminum sheets coated with 60F254 silica gel
(Merck, 0.2 mm) are used for TLC. Uncorrected melting points are obtained from melting point
instrument and reported in degrees centigrade.Chemical shifts (d) are reported in parts per
million. J (Coupling constant) values are reported in Hz (Hertz). Proton spin multiplicities are
denoted as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), dd (doublet of doublets),
ddd (doublet of doublet of doublets). IR and Mass spectra were obtained from Schimadzu FTIR-
8
400S and GCMS-QP-1000EX respectively.
4
.1.1. Synthesis of methyl 2-(prop-2-ynyloxy) benzoate (2):
The compound 2 was prepared by the propargylation of compound 1 (1.0 eq) using the propargyl
bromide (1.5 eq) and K CO (1.5 eq) in dry dimethyl formamide solvent under nitrogen
atmosphere at rt for 3 hrs, after completing the reaction, it was extracted using dichloromethane
4
and ice cold water (3 x 50 mL), the combined organic layer was dried with anhydrous Na SO ,
2
3
2
concentrated in vacuo and purified by silica gel column using 25% EtOAc in hexane as an eluent
to afford compound 2 as light yellow solid in 85% yield. Spectral data of isolated compound 2 is
1
in agreement with the reported data[54]. Yield:85%. H NMR (400 MHz, CDCl ): δ 7.81 (dd,J =
3
7
2
1
.7, 1.8 Hz, 1H) 7.51-7.44 (m, 1H), 7.14 (d, J= 8.4, Hz, 1H), 7.04 (td,J = 7.6, 0.9 Hz, 1H), 4.79 (d, J =
13
.4 Hz, 2H), 3.89 (s, 3H), 2.52 (t, J = 2.4 Hz, 1H); C NMR (100 MHz,CDCl
3
): δ 166.0, 156.0, 133.0,
30.0, 121.0 120.0, 114.0, 79.0 78.5 56.0, 51.9. M.F: C H O , ESI-MS; m/z: 191 (M+1).
11
11
3
4
.1.2. General procedure for the synthesis of aromatic azides (3a-d):
The aromatic azides 3a-d were prepared by addition of 5N HCl solution to a mixture of
o
respective amine in CH Cl at 0 C followed by drop wise addition of NaNO solution to above
2
2
2
o
o
mixture and stirred at 0 C for 30 minutes. To this was added NaN at 0 C and continued the
3
stirring for 2 hrs at rt, then it was allowed to stand for separation of organic and aqueous layers.
The organic layer was washed using NaHCO followed by brine and the solvent was evaporated
3
in vacuo to obtain the required aryl azides 3a-d. The azides 3a-d are used in next step without
any additional purification.
4
.1.3. General procedure for the synthesis of 1,2,3-triazoles (4a-d):

To a mixture of methyl salicylate derivative 2 (1.0 eq), compound 3a-d (1.2 eq) in dry dimethyl
formamide (30mL) was added to a solution of CuSO .5H O (0.01 eq) and sodium ascorbate
4
2
(
0.01 eq) and the mixture was stirred for overnight at rt. After completion of the reaction as
indicated by TLC, the reaction contents were extracted from ice cold water and ethyl acetate (3 x
0 mL). The organic layer was washed and dried using brine and dry Na SO respectively. The
5
2
4
solvent was removed in vacuo and the crude produced was purified by passing through silica gel
column (eluent: 30% EtOAc in hexane) to get the desired pure product 4a-d with 90-95% yield.
4
.1.3.1. Methyl 2-((1-(4-chlorophenyl)-1H-1,2,3-triazol-5-yl)methoxy)benzoate (4a):
1
Yield: 81%; White solid; M.p. 77 – 79. H NMR (400 MHz, CDCl
3
):
δ
8.02 (s, 1H), 7.85 (dd, J = 17.8,
1
.6, 1H), 7.72 – 7.69 (m, 2H), 7.53 – 7.47 (m, 3H), 7.22 – 7.15 (d, J = 8.1 Hz, 1H), 7.06 – 7.02
1
3
(m, 1H), 5.40 (s, 2H), 3.89 (s, 3H). C NMR (100 MHz, CDCl ): δ158.2, 145.5, 133.7, 131.8,
3
1
1
29.9, 121.7, 121.1, 121.0, 114.1, 63.51, 51.9. IR (neat): 3077, 2956, 2923, 2852, 1643, 1501,
464, 1247, 1190, 1046, 932 cm . Anal. Calcd. For C17H14ClN O : C, 59.40; H, 4.10; N, 12.22;
3 3
-1
Found: C, 59.38; H, 4.09; N, 12.19. ESI-MS: m/z: 344 (M+1).
.1.3.2. Methyl 2-((1-(3-chlorophenyl)-1H-1,2,3-triazol-5-yl)methoxy)benzoate (4b):
4
1
Yield: 80%; White solid; M.p 73 – 75. H NMR (400 MHz, CDCl ):δ 8.22 (s, 1H), 7.88 – 7.79
3
(
m, 2H), 7.70 – 7.62 (m, 1H), 7.55 – 7.39 (m, 3H), 7.16 (d, J = 8.2 Hz, 1H), 7.09 – 6.95 (m, 1H),
1
3
5
1
2
.41 (s, 2H), 3.91 (s, 3H). C NMR (100 MHz, CDCl ): δ 166.2, 157.7, 135.6, 133.7, 131.8,
3
30.8, 128.9, 121.2, 120.9, 120.6, 118.5, 114.1, 63.4, 52.0. IR (neat): 3394, 3117, 3027, 2923,
-1
852, 1727, 1596, 1530, 1493, 1449, 1293, 1255, 1166, 1048, 962 cm .Anal. Calcd. For
C H ClN O :C, 59.40; H, 4.10; N, 12.22; Found: C, 59.41; H, 4.06; N, 12.17. ESI-MS: m/z:
17
14
3
3
3
4
44 (M+1).
.1.3.3. Methyl 2-((1-(4-methoxyphenyl)-1H-1,2,3-triazol-5-yl)methoxy)benzoate (4c):
1
Yield: 87%; White solid; M.p 77 – 79. H NMR (400 MHz, CDCl
3
):δ 8.12 (s, 1H), 7.83 (dd, J=
7
.7, 1.8 Hz, 1H), 7.72 – 7.58 (m, 2H), 7.54 – 7. 21 (m, 1H), 7.18 (d, J = 8.1 Hz, 1H), 7.08 – 6.96
1
3
(m, 3H), 5.40 (s, 2H), 3.89 (s, 3H), 3.87 (s, 3H). C NMR (100 MHz, CDCl
3
):δ 166.3, 159.8,
1
3
57.84, 133.7, 131.7, 130.5, 122.2, 121.2, 121.0, 120.6, 114.7, 114.1, 63.5, 55.6, 52.0. IR (neat):
136, 2924, 2853, 1723, 1599, 1517, 1490, 1451, 1303, 1250, 1160, 1034 cm . Anal. Calcd. For
-1
C H N O :C, 63.71; H, 5.05; N, 12.38; Found: C, 63.68; H, 5.05; N, 12.35. ESI-MS: m/z: 340
18
17
3
4
(M+1).
4
.1.3.4. Methyl 2-((1-phenyl-1H-1,2,3-triazol-5-yl)methoxy)benzoate (4d):
1
Yield: 82%; White solid; M.p 71-73. H NMR (400 MHz, CDCl
3
), δ 8.21 (s, 1H), 7.84 (dd, J =
7
7
1
1
.7, 1.8 Hz, 1H), 7.80 – 7.70 (m, 2H), 7.58 – 7.42 (m, 4H), 7.18 (d, J = 7.9 Hz, 1H), 7.03 (tt, J=
13
.8, 3.9 Hz, 1H), 5.42 (s, 2H), 3.90 (s, 3H). C NMR (100 MHz, CDCl ): δ 166.3, 157.8, 137.0,
3
33.7, 131.8, 129.7, 128.8, 121.1, 120.6, 114.1, 63.5, 52.0. IR (neat): 3420, 3088, 2922, 2852,
-
1
726, 1642, 1597, 1494, 1432, 1286, 1253, 1168, 1033, 998 cm . Anal. Calcd. For
C H N O :C, 66.01; H, 4.89; N, 13.58; Found: C, 65.98; H, 4.84; N, 13.54. ESI-MS: m/z: 310
17
15
3
3
(M+1).

4
.1.4. General procedure for the synthesis of bezohydrazides (5a-d):
To a solution of compound 4a-d (1.0 eq) in 1,4-dioxane solvent was added hydrazine hydrate
1.2 eq) and it was refluxed for 24 h. After completion of reaction as indicated by TLC, the
(
solvent 1,4 dioxane was removed under reduced pressure and the crude reaction mixture was
extracted by using ethyl acetate and water. The organic layer was dried over Na SO and
2
4
concentrated in vacuo. The crude product was purified using silica gel column to get compounds
5
a-d with 85-90% yield.
2
-((1-(4-Chlorophenyl)-1H-1,2,3-triazol-5-yl)methoxy)benzohydrazides (5a):
1
6
Yield: 90%; White solid; M.p. 87 – 89. H NMR (400 MHz, d -DMSO): δ 9.21 (s, 1H), 8.93 (s,
1
8
1
2
H), 7.94 – 7.90 (m, 2H), 7.65 (ddd,J = 22.2, 10.4, 4.7 Hz, 3H), 7.54 – 7.46 (m, 2H), 7.37 (d, J =
.1 Hz, 1H), 5.40 (s, 2H), 4.53 (s, 2H). C NMR (100 MHz, d -DMSO): δ 155.3, 143.8, 135.2,
1
3
6
33.0, 131.8, 130.1, 129.9, 123.1, 122.7, 121.8, 121.0, 113.5, 61.8. IR (neat): 3394, 3097, 2956,
-
1
923, 2852, 1783, 1711, 1643, 1501, 1464, 1247, 1046, 994 cm . Anal. Calcd. For
C H ClN O :C, 55.90; H, 4.10; N, 20.37; Found: C, 55.86; H, 4.11; N, 20.40. ESI-MS: m/z:
16
14
5
2
3
2
44 (M+1).
-((1-(3-Chlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)benzohydrazides (5b):
1
6
Yield: 88%; White solid; M.p. 88 – 90. H NMR (400 MHz, d -DMSO): δ 10.34 (s, 1H), 9.08 (s,
1
=
H), 8.05 (s, 1H), 7.93 (d, J = 7.8 Hz, 2H), 7.70 – 7.56 (m, 4H), 7.48 – 7.42 (m, 1H) 7.14 (dd, J
12.9, 5.5 Hz, 1H), 5.46 (s, 2H), 3.33 (s, 1H). C NMR(100 MHz, d -DMSO): δ 160.5, 155.6,
1
3
6
1
3
54.8, 142.9, 137.4, 134.2, 132.8, 131.2, 128.7, 123.9, 121.6, 121.4, 118.8, 113.3, 61.5.IR (neat):
337, 3102, 2957, 2923, 1656, 1595, 1529, 1483, 1451, 1223, 1145, 1019, 992 cm . Anal.
-1
Calcd. For C H ClN O :C, 55.90; H, 4.10; N, 20.37; Found: C, 55.92; H, 4.07; N, 20.31. ESI-
1
6
14
5
2
MS: m/z: 344 (M+1).
-((1-(4-Methoxyphenyl)-1H-1,2,3-triazol-5-yl)methoxy)benzohydrazides (5c):
2
1
6
Yield: 87%; White solid; M.p. 85 – 87. H NMR (400 MHz, d -DMSO): δ 10.35 (s, 1H), 8.90 (s,
1
1
H), 7.94 (dd, J = 7.7, 1.7 Hz, 1H), 7.83 – 7.76 (m, 2H), 7.61 – 7.53 (m, 1H), 7.46 (d, J = 8.2 Hz,
H), 7.20 – 7.10 (m, 3H), 5.43 (s, 2H), 3.84 (s, 3H), 1.90 (s, 2H). C NMR (100 MHz, d -
13
6
DMSO): δ 160.4, 159.4, 155.7, 154.7, 142.5, 132.9, 131.3, 129.8, 123.7, 121.9, 121.4, 114.9,
1
8
2
2
13.3, 61.9, 55.5. IR (neat): 3399, 3329, 2957, 2924, 2852, 1642, 1599, 1517, 1482, 1253, 1036,
-1
35 cm . Anal. Calcd. For C H N O :C, 60.17; H, 5.05; N, 20.64; Found: C, 60.20; H, 5.01; N,
1
7
17
5
3
0.60. ESI-MS: m/z: 340 (M+1).
-((1-Phenyl-1H-1,2,3-triazol-5-yl)methoxy)benzohydrazides (5d):
1
6
Yield: 89%; White solid; M.p. 83 – 85. H NMR (400 MHz, d -DMSO): δ 9.21 (s, 1H), 8.93 (s,
1
7
1
3
H), 7.94 – 7.90 (m, 2H), 7.69 – 7.61 (m, 3H), 7.54 – 7.46 (m, 2H), 7.37 (d, J = 8.1 Hz, 1H),
.07 (t, J = 7.4 Hz, 1H), 5.40 (s, 2H), 4.53 (s, 2H). C NMR (100 MHz, d -DMSO): δ 155.4,
1
3
6
43.7, 136.4, 131.8, 130.1, 129.9, 128.8, 123.1, 122.6, 121.0, 120.1, 113.5, 61.9. IR (neat): 3396,
-1
332, 3075, 2956, 2924, 2853, 1837, 1709, 1642, 1599, 1483, 1224, 1047, 994 cm . Anal.
:C, 62.13; H, 4.89; N, 22.64; Found: C, 62.10; H, 4.90; N, 22.61. ESI-MS:
Calcd. ForC16
15 5 2
H N O
m/z: 310 (M+1).

4
.1.5. General procedure for the synthesis of Schiff’s base (7a-q):
To a solution of benzohydrazide 5a-d (1.0 eq) in ethanol was added aldehyde 6 (1.0) and it was
refluxed for 3- 4 hours. Once the reaction is completed as denoted by TLC, the ethanol was
distilled under vacuum and the obtained compound was washed with hexane which yielded the
desired pure products in about 90% yield.
4
.1.6. General procedure for the synthesis of triazole conjugated novel 2,5-diaryl
substituted 1,3,4, oxadiazoles (8a-q):
To a solution of Schiff’s base compound 7 (1.0 eq) in ethanol was added PhI(OAc) (5 mol%)
2
and it was stirred for 2 to 4 hours at rt. When the reaction was completed, as denoted by TLC,
ethanol solvent was removed in vauco. The obtained compound was subjected to silica gel
column using 15% of EtOAc in hexane eluent to afford the final compound as a white solid with
8
0-90% yield.
2
1
-(2-((1-(4-Chlorophenyl)-1H-1,2,3-triazol-5-yl)methoxy)phenyl)-5-(3,4-dichlorophenyl)
-
,3,4-oxadiazole (8a):
1
Yield: 84%; White solid; M.p. 184 – 186. H NMR (400 MHz, CDCl ): δ 8.36 (s, 1H), 8.08 (dd,
3
J = 7.8, 1.7 Hz, 1H), 8.01 (d, J = 8.5 Hz, 1H), 7.70 – 7.66 (m, 2H), 7.65 – 7.53 (m, 2H), 7.52 –
7
2
1
1
.49 (m, 2H), 7.38 (dd, J = 8.5, 2.1 Hz, 1H) 7.29 (s, 1H), 7.18 (td, J = 7.7, 0.9 Hz, 1H), 5.49 (s,
1
3
H). C NMR (100 MHz, CDCl
3
): δ 162.3, 160.8, 156.0, 145.3, 138.1, 135.3, 134.6, 133.5,
31.9, 131.1, 130.6, 130.0, 127.7, 121.6, 121.3, 113.5, 63.3. IR (neat): 2929, 2856, 1595, 1501,
-1
3 5 2
464, 1263, 1097, 1038, 828 cm . Anal. Calcd. For C23H14Cl N O :C, 55.39; H, 2.83; N, 14.04;
Found: C, 55.41; H, 2.80; N, 14.00. ESI-MS: m/z:498(M+1).
-(2-(2-(1-(3-Chlorophenyl)-1H-1,2,3-triazol-5-yl)ethyl)phenyl)-5-(4-methoxyphenyl)-1,3,4-
oxadiazole (8b):
Yield: 86%; White solid; M.p. 167 – 169. H NMR (400 MHz, CDCl
.00 (m, 3H), 7.64 – 7.62 (m, 2H), 7.56 – 7.51 (m, 1H), 7.47 – 7.45 (m, 2H), 7.27 (s, 1H), 7.17
2
1
3
): δ 8.32 (s, 1H), 8.06 –
8
1
3
(t, J = 8.2 Hz, 1H), 6.99 – 6.94 (m, 2H), 5.47 (s, 2H), 3.85 (s, 3H). C NMR (100 MHz, CDCl
3
):
δ 162.7, 162.3, 156.3, 145.3, 134.5, 133.0, 130.4, 129.9, 128.6, 121.7, 121.6, 121.1, 114.5, 113.5,
-1
6
3.4, 55.4. IR (neat): 3063, 1612, 1500, 1464, 1258, 1177, 1032, 843 cm . Anal. Calcd. For
C H ClN O : C, 62.68; H, 3.95; N, 15.23; Found: C, 62.70; H, 3.90; N, 15.20. ESI-MS: m/z:
24
18
5
3
4
2
1
60 (M+1).
-(2-(2-(1-(3-Chlorophenyl)-1H-1,2,3-triazol-5-yl)ethyl)phenyl)-5-(3,4,5-trimethoxyphenyl)-
,3,4-oxadiazole (8c):
1
Yield: 89%; White solid; M.p. 170 – 172. H NMR (400 MHz, CDCl ): δ 8.31 (s, 1H), 8.06 (dd,
3
J = 1.5 Hz, 1H), 7.64 –7.56 (m, 5H), 7.47 – 7.45 (m, 2H), 7.24 (s, 1H), 7.18 (t, J= 8.0 Hz, 1H),
1
3
6
1
1
3
.86 – 6.84 (m, 1H), 5.47 (s, 2H), 3.96 (s, 3H), 3.91 (s, 3H). C NMR (100 MHz, CDCl ):δ
62.8, 156.3, 151.9, 149.4, 145.3, 135.3, 134.6, 133.1, 130.4, 129.9, 121.7, 121.6, 121.1, 120.2,
16.5, 113.7, 113.4, 111.0, 109.4, 63.3, 56.2, 55.9. IR (neat): 2945, 1606, 1503, 1462, 1270,

-1
1
6
2
141, 1028, 832cm . Anal. Calcd. For C25
1.30; H, 4.09; N, 14.27. ESI-MS: m/z: 490 (M+1).
-(4-Chlorophenyl)-5-(2-(2-(1-(4-chlorophenyl)-1H-1,2,3-triazol-5-yl)ethyl)phenyl)-1,3,4-
5 4
H20ClN O :C, 61.29; H, 4.11; N, 14.30; Found: C,
oxadiazole (8d):
Yield: 88%; White solid; M.p. 173-175. H NMR (400 MHz, CDCl ): δ 8.34 (s, 1H), (dd, J = 8.6,
1
3
5
5
1
1
.1 Hz, 3H), 7.67 (d, J = 8.8 Hz, 2H), 7.60 – 7.44 (m, 5H), 7.28 (s, 1H), 7.18 (t, J = 7.5, Hz, 1H),
1
3
.49 (s, 2H). C NMR(100 MHz, CDCl ): δ 162.0, 156.7, 133.4, 131.6, 130.4, 130.0, 129.5,
3
28.8, 128.2, 127.3, 121.7, 121.2, 113.5, 63.2. IR (neat): 2928, 2860, 1597, 1499, 1268, 1093,
-1
015, 825 cm . Anal. Calcd. For C H Cl N O :C, 59.50; H, 3.26; N, 15.08; Found: C, 59.46;
2
3
15
2
5
2
H, 3.20; N, 15.10. ESI-MS: m/z: 464.
-(2-((1-(4-Chlorophenyl)-1H-1,2,3-triazol-5-yl)methoxy)phenyl)-5-phenyl-1,3,4-oxa-diazole
8e):
Yield: 84%; White solid; M.p. 161 – 163. H NMR (400 MHz, CDCl ): δ 8.34 (s, 1H), 8.10 –
2
(
1
3
8
5
1
1
.05 (m, 3H), 7.66 – 7.63 (m, 2H), 7.53 – 7.49 (m, 6H),7.29 (s, 1H), 7.18 (t, J = 7.5 Hz, 1H),
1
3
.48 (s, 2H). C NMR (100 MHz, CDCl ): δ 156.4, 135.4, 134.5, 133.2, 131.6, 130.4, 129.9,
3
29.1, 128.8, 126.9, 124.0, 121.7, 121.6, 121.1, 113.6, 113.5, 63.4. IR (neat): 2928, 2859, 1600,
-1
498, 1267, 1129, 1030, 831 cm . Anal. Calcd. For C H ClN O :C, 64.26; H, 3.75; N, 16.29;
2
3
16
5
2
Found: C, 64.22; H, 3.71; N, 16.30. ESI-MS: m/z: 430 (M+1).
-(2-((1-(4-Chlorophenyl)-1H-1,2,3-triazol-5-yl)methoxy)phenyl)-5-p-tolyl-1,3,4-oxa-diazole
8f):
2
(
1
Yield: 86%; White solid; M.p. 168 – 170. H NMR (400 MHz, CDCl ): δ 8.34 (s, 1H), 8.06 (dd,
3
J = 7.8, 1.6 Hz, 1H), 7.97 (d, J = 8.2 Hz, 2H), 7.65 – 7.62 (m, 2H), 7.56 (ddd, J = 11.8, 7.2, 2.6
Hz, 2H), 7.48 – 7.44 (m, 2H), 7.26 – 7.24 (m, 2H), 7.18 (t, J = 7.6, Hz, 1H), 5.49 (s, 2H), 2.41 (s,
1
3
3
1
H). CNMR(100 MHz, CDCl ): δ 156.5, 145.3, 142.1, 134.6, 133.1, 130.4, 129.9, 129.8,
3
26.8, 121.7, 121.6, 113.4, 63.3, 22.0. IR (neat): 2937, 1628, 1504, 1464, 1269, 1101, 1028, 840
cm . Anal. Calcd. For C H ClN O :C, 63.96; H, 4.20; N, 16.22; Found: C, 64.00; H, 4.18; N,
-
1
2
3
18
5
2
1
2
6.19. ESI-MS: m/z: 396 (M+1).
-Phenyl-5-(2-((1-phenyl-1H-1,2,3-triazol-5-yl)methoxy)phenyl)-1,3,4-oxadiazole (8g):
1
Yield: 90%; White solid; M.p. 158 – 160. H NMR (400 MHz, CDCl ): δ 8.32 (s, 1H), 8.08 (dd,
3
J = 8.1, 1.3 Hz, 3H), 7.76 – 7.66 (m, 2H), 7.61 – 7.54 (m, 1H), 7.53 – 7.41 (m, 6H), 7.28 (d, J =
1
3
7
1
1
.6 Hz, 1H), 7.18 (t, J = 7.6 Hz, 1H), 5.50 (s, 2H). C NMR (100 MHz, CDCl ): δ 164.3, 163.2,
3
56.4, 144.9, 136.9, 133.2, 131.6, 130.5, 129.7, 129.1, 128.8, 126.8, 124.0, 121.6, 121.1, 120.5,
13.6, 113.5, 63.4. IR (neat): 3149, 2921, 1598, 1472, 1265, 1023, 755 cm . Anal. Calcd. For
:C, 69.86; H, 4.33; N, 17.71; Found: C, 69.85; H, 4.31; N, 17.69. ESI-MS: m/z: 396
-1
23 17 5 2
C H N O
(M+1).
2
-(4-Methoxyphenyl)-5-(2-(2-(1-phenyl-1H-1,2,3-triazol-5-yl)ethyl)phenyl)-1,3,4-oxa-
diazole (8h):
Yield: 87%; White solid; M.p. 163 – 165. H NMR (400 MHz, CDCl
J = 8.5 Hz, 1H) 7.70 – 7.67 (m, 2H), 7.61 – 7.57 (m, 2H), 7.51 – 7.43 (m, 4H), 7.22 (s, 1H), 7.16
1
3
): δ 8.29 (s, 1H), 8.07 (dd,
1
3
(
t, J = 8.1 Hz, 1H), 6.94 – 6.92 (m, 2H), 5.58 (s, 2H), 3.82 (s, 3H). C NMR (100 MHz, CDCl ):
3
δ 162.6, 156.6, 144.8, 137.2, 133.0, 130.4, 129.7, 128.8, 128.6, 121.6, 121.1, 120.5, 116.6, 114.5,

-1
1
13.5, 63.4, 55.4. IR (neat): 2927, 2859, 1608, 1499, 1465, 1258, 1036, 807 cm . Anal. Calcd.
For C H N O :C, 67.76; H, 4.50; N, 16.46; Found: C, 67.74; H, 4.48; N, 16.43. ESI-MS:
2
4
19
5
3
m/z:426 (M+1).
-(2-(2-(1-Phenyl-1H-1,2,3-triazol-5-yl)ethyl)phenyl)-5-(3,4,5-trimethoxyphenyl)-1,3,4-
oxadiazole (8i):
2
1
Yield: 89%; White solid; M.p. 167 – 169. H NMR (400 MHz, CDCl ): δ 8.27 (s, 1H), 8.07 (dd,
3
J = 1.5 Hz, 1H), 7.68 – 7.65 (m, 3H), 7.56 – 7.55 (m, 2H), 7.54 – 7.42(m, 3H), 7.27 (s, 1H), 7.19
1
3
(
t, J = 7.6 Hz, 1H), 6.82 – 6.80 (m, 1H), 5.48 (s, 2H), 3.96 (s, 3H), 3.87 (s, 3H). C NMR (100
MHz, CDCl ): δ164.3, 162.9, 156.3, 151.8, 149.3, 144.8, 136.8, 133.1, 130.4, 129.7, 128.8,
3
1
2
6
2
21.6, 121.1, 120.4, 120.2, 116.5, 113.6, 113.4, 111.0, 109.3, 63.3, 56.1, 55.9. IR (neat): 3010,
-1
947, 1602, 1543, 1501, 1463, 1267, 1140, 1030, 758 cm . Anal. Calcd. For C H N O :C,
2
5
21
5
4
5.93; H, 4.65; N, 15.38; Found: C, 65.90; H, 4.63; N, 15.37. ESI-MS: m/z: 456 (M+1).
-(3,4-Dichlorophenyl)-5-(2-((1-phenyl-1H-1,2,3-triazol-5-yl)methoxy)phenyl)-1,3,4-oxa-
diazole (8j):
1
Yield: 88%; White solid; M.p. 181 – 183. H NMR (400 MHz, CDCl ): δ 8.32 (s, 1H), 8.09 (dd,
3
J= 7.8, 1.7 Hz, 1H), 7.99 (d, J = 8.5 Hz, 1H), 7.73 – 7.69 (m, 2H), 7.58 – 7.47 (m, 5H), 7.36 (dd,
1
3
J = 8.5, 2.0 Hz. 1H), 7.29 (d, J = 8.3 Hz, 1H), 7.17 (t, J = 7.6 Hz, 1H), 5.50 (s, 2H). C NMR
100 MHz, CDCl ): δ 163.7, 161.6,156.5, 144.9, 133.7, 133.5, 131.9, 131.1, 130.6, 129.8, 128.9,
27.6, 121.8, 121.7, 121.4, 120.5, 113.5, 63.2.IR (neat): 3076, 2938, 1598, 1502, 1469, 1295,
(
3
1
1
-1
2 5 2
262, 1076, 1042, 820 cm . Anal. Calcd. For C23H15Cl N O :C, 59.50; H, 3.26; N, 15.08;
Found: C, 59.47; H, 3.25; N, 15.10. ESI-MS: m/z: 464 (M+1).
2
-(2-((1-Phenyl-1H-1,2,3-triazol-5-yl)methoxy)phenyl)-5-p-tolyl-1,3,4-oxadiazole (8k):
1
Yield: 85%; White solid; M.p. 169 – 171. H NMR (400 MHz, CDCl ): δ 8.29 (s, 1H), 8.08 (d, J
3
=
6.2 Hz, 1H), 8.01 (d, J = 8.5 Hz, 2H), 7.70 (d, J= 7.6, Hz, 2H), 7.53 (dd, J = 14.5, 7.3 Hz, 4H),
1
3
7.42 (d, J = 8.5 Hz, 2H), 7.29 (s, 1H), 7.18 (t, J = 7.4 Hz, 1H), 5.49 (s, 2H). C NMR (100 MHz,
CDCl ): δ 156.4, 135.3, 134.5, 132.9, 131.5, 130.4, 129.9, 128.9, 126.7, 123.9, 121.7, 121.1,
3
-1
1
13.5, 63.3. IR (neat): 2930, 2863, 1599, 1469, 1265, 1090, 1029, 806 cm . Anal. Calcd. For
C H ClN O :C, 64.27; H, 3.75; N, 16.29; Found: C, 64.25; H, 3.73; N, 16.30. ESI-MS: m/z:
23
16
5
2
4
2
30 (M+1).
-(2-(2-(1-Phenyl-1H-1,2,3-triazol-5-yl)ethyl)phenyl)-5-p-tolyl-1,3,4-oxadiazole (8l):
1
Yield: 86%; White solid; M.p. 180 – 182. H NMR (400 MHz CDCl
3
): δ 8.30 (s, 1H), 8.08 (dd, J
=
1.2 Hz, 1H), 7.96 – 7.95 (m, 2H), 7.69 – 7.67 (m, 2H), 7.56 – 7.43 (m, 5H), 7.27 – 7.24 (m,
1
3
2
1
6
H), 7.17 – 7.15 (m, 1H), 5.49 (s, 2H), 2.39 (s, 3H). C NMR (100 MHz, CDCl
63.0, 156.4, 144.9, 142.1, 133.1, 130.5, 129.8, 129.7, 128.8, 126.8, 121.6, 121.2, 120.5, 113.5,
3.4, 21.6. IR (neat): 2928, 2867, 1602, 1502, 1464, 1271, 1124, 1079, 1032, 824 cm . Anal.
3
): δ164.8,
-1
Calcd. ForC H N O :C, 70.40; H, 4.68; N, 17.10; Found: C, 70.38; H, 4.65; N, 17.09. ESI-
2
4
19
5
2
MS:m/z:410 (M+1).
-(2-Fluorophenyl)-5-(2-((1-phenyl-1H-1,2,3-triazol-5-yl)methoxy)phenyl)-1,3,4-oxadi-azole
8m):
2
(
1
Yield: 89%; White solid; M.p. 176 – 178. H NMR (400 MHz, CDCl ): δ 8.45 (s, 1H), 8.08 (dd,
3
J = 7.8, 1.7 Hz, 1H), 7.80 – 7.69 (m, 2H), 7.40 (m, 6H), 7.27 (d, J = 5.8 Hz, 1H), 7.24 – 7.12 (m,

1
3
2
1
1
H), 6.57 (dd, J = 3.5, 1.8 Hz, 1H), 5.50 (s, 2H), C NMR (100 MHz, CDCl
3
): δ 162.6, 157.2,
56.4, 145.5, 145.0, 139.6, 137.0, 133.4, 130.5, 129.8, 128.8, 121.7, 121.3, 120.7, 114.0, 113.4,
13.0, 112.2, 63.6. IR (neat): 3142, 2926, 1602, 1505, 1466, 1267, 1240, 1046, 902 cm . Anal.
-1
Calcd. For C H FN O :C, 66.82; H, 3.90; N, 16.94; Found: C, 66.79; H, 3.89; N, 16.89. ESI-
2
3
16
5
2
MS: m/z: 414 (M+1).
-(2-((1-(3-Chlorophenyl)-1H-1,2,3-triazol-5-yl)methoxy)phenyl)-5-phenyl-1,3,4-oxadi-azole
8n):
Yield: 88%; White solid; M.p. 185 – 187. H NMR (400 MHz, CDCl ): δ 8. 36 (s, 1H), 8.12 –
2
(
1
3
8
7
1
.05 (m, 3H), 7.79 (dd, J = 2.5, 1.4 Hz, 1H), 7.60 – 7.43 (m, 7H), 7.27 (d, J = 5.7 Hz, 1H), 7.22 –
1
3
.14 (m, 1H), 5.50 (s, 2H). C NMR (100 MHz, CDCl ): δ 156.3, 145.2, 135.6, 133.2, 131.7,
3
30.8, 130.4, 129.1, 128.9, 126.8, 124.0, 121.7, 121.2, 120.8, 118.4, 113.6, 113.5, 63.3. IR
-1
(neat): 2955, 2922, 2853, 1593, 1461, 1264, 1262, 1044, 780 cm . Anal. Calcd. For
C H ClN O :C, 64.26; H, 3.75; N, 16.29; Found: C, 64.24; H, 3.71; N, 16.26. ESI-MS: m/z:
23
16
5
2
4
2
1
30 (M+1).
-(2-((1-(3-Chlorophenyl)-1H-1,2,3-triazol-5-yl)methoxy)phenyl)-5-(2,4-dichlorophenyl)
,3,4-oxadiazole (8o):
-
1
Yield: 85%; White solid; M.p. 177 – 179. H NMR (400 MHz, CDCl ): δ 8.36 (s, 1H), 8.08 (dd,
3
J = 7.8, 1.7 Hz, 1H), 8.01 (d, J = 8.5 Hz, 1H), 7.70 – 7.66 (m, 2H), 7.61 – 7.48 (m, 4H), 7.38 (dd,
1
3
J = 8.5, 2.1 Hz, 1H), 7.28 (d, J = 7.8 Hz, 1H), 7.18 (td, J = 7.7, 0.9 Hz, 1H), 5.49 (s, 2H). C
NMR (100 MHz, CDCl ): δ 163.7, 156.4, 145.0, 138.0, 137.7, 135.6, 133.7, 133.5, 131.9, 131.1,
30.8, 130.6, 129.0, 127.7, 121.7, 121.4, 120.8, 118.4, 113.5, 113.2, 63.2. IR (neat): 2956, 2923,
3
1
2
3
2
1
-
1
853, 1582, 1460, 1285, 1253, 1045, 987 cm . Anal. Calcd. For C23
2 5 2
H14Cl N O :C, 59.63; H,
.05; N, 15.12; Found: C, 59.59; H, 3.03; N, 15.09. ESI-MS:m/z:498(M+1).
-(3,4-Dimethoxyphenyl)-5-(2-((1-(4-methoxyphenyl)-1H-1,2,3-triazol-5yl)methoxy)phenyl-
,3,4-oxadiazole (8p):
1
Yield: 90%; White solid; M.p. 184 – 186. H NMR (400 MHz, CDCl ): δ 8.19 (s, 1H), 8.07 (dd, J
3
=
7.8, 1.7 Hz, 1H), 7.65 (d, J = 1.9 Hz, 1H), 7.59 – 7.53 (m, 4H), 7.27 (d, J = 8.0 Hz, 1H), 7.17
(
(
t, J = 7.6 Hz, 1H), 7.00 – 6.95 (m, 2H), 6.82 (d, J = 8.4 Hz, 1H), 5.47 (s, 2H), 3.96 (s, 3H), 3.88
1
3
s, 3H), 3.87 (s, 3H). C NMR(100 MHz, CDCl ): δ164.4, 159.8, 156.3, 151.1, 149.3, 144.7,
3
1
33.1, 130.5, 122.3, 122.1, 121.6, 120.2, 116.6, 114.8, 113.7, 111.0, 109.4, 63.3, 56.1, 55.9, 55.6.
-1
IR (neat): 2955, 2923, 2853, 1605, 1517, 1498, 1255, 1230, 1142, 1028, 749 cm . Anal. Calcd.
For C H N O :C, 64.32; H, 4.78; N, 14.43; Found: C, 64.29; H, 4.77; N, 14.40. ESI-MS:m/z:
2
6
23
5
5
4
2
1
86 (M+1).
-(2,4-Dichlorophenyl)-5-(2-((1-(4-methoxyphenyl)-1H-1,2,3-triazol-5-yl)methoxy)phe-nyl)-
,3,4oxadiazole (8q):
1
Yield: 86%; White solid; M.p. 171 – 173. H NMR (400 MHz, CDCl ): δ 8.20 (s, 1H), 8.09(dd, J
3
=
7.8, 1.7 Hz, 1H), 7.99 (d, J = 8.5 Hz, 1H), 7.62 – 7.51 (m, 4H), 7.35 (dd, J = 8.5, 2.0 Hz, 1H),
7
.29 (d, J = 8.4 Hz, 1H), 7.17 (t, J = 7.2 Hz, 1H), 7.05 – 6.97 (m, 2H), 5.48 (s, 2H), 3.88 (s, 3H).
1
3
C NMR (100 MHz, CDCl
3
): δ162.5, 156.6, 145.1, 132.9, 130.5, 129.8, 129.0, 121.8, 121.3,
1
20.5, 114.5, 113.4, 63.4. IR (neat): 2955, 2922, 2852, 1594, 1494, 1461, 1377, 1266, 1044, 817

-1
2 5 3
cm . Anal. Calcd. For C24H17Cl N O :C, 58.31; H, 3.47; N, 14.17; Found: C, 58.28; H, 3.44; N,
1
4.15.ESI-MS:m/z:494 (M+1).
4
4
.2. Biological Screening
.2.1. Antimicrobial activity
Materials and methods:
Strains and media:
Two strains of Gram-positive bacteria (Bacillus subtilis MTCC 441, Staphylococcus aureus
MTCC 96) and Gram-negative bacteria (Escherichia coli MTCC 443) were used for screening
the antibacterial activity. Strains were obtained from the Department of Microbiology, Osmania
University. Dimethyl sulfoxide (DMSO) was used as compound dissolving agent, Ampicillin
(Standard drug) as test control, Muller-Hinton Agar, Luria-Bertani Broth, Miller (LB broth) for
culturing microbes.
Preparation of microbial cultures:
All types of microbial stock cultures received were streaked separately onto Muller-Hinton Agar
slants (20 ml/tube) and incubated at 37°C for 24 hrs under sterile conditions. The grown cultures
were inoculated into 10 mL Luria-Bertani Broth, Miller (LB) broth medium (containing
Tryptone 10 g/L, Yeast extract 5 g/L, Sodium chloride 10 g/L, pH 7.5) by transferring a loop full
of culture and incubated for 12 hr at 37°C with continuous shaking at 220 rpm.. 1% of grown
culture was re-inoculated into fresh LB broth and incubated for 3-4 hours for Log phase culture.
An absorbance of 0.4-0.6 OD was measuredat 600 nm suggesting that cultures are now ready to
use for testing antibacterial activity.
Antibacterial Activity
To test the antimicrobial efficacy of the compounds, Luria-Bertani Broth, Miller (LB broth) a
potent microbiological growth medium which was commonly used for antibiotic susceptibility
testing was used. LB broth was prepared and sterilized in autoclave under aseptic conditions, 121
°
C /15 Lbs pressure for 30 minutes and cooled to room temperature. In the present study,
Minimum Inhibitory Concentration (MIC) of the compound against several bacterial strains was
determined by following the broth dilution method. Microbial strains to be tested were grown at
3
4
7°C for 12 h with continuous shaking at 220 rpm [55-57] and arrested at log phase by storing at
°C. The synthesized compounds to be tested for antimicrobial activities were dissolved in
DMSO consequently to produce a concentration of 1 mg/mL and are treated as a stock solution.
Subsequently different concentration of compound ranging from minimum to maximum was
added to bacterial cultures to determine its MIC value. Antibacterial activity of the compound

was determined by treating various concentrations of compound with log phase culture (1 μl/ml)
and incubating for 12 hrs at 37°C with continuous shaking at 220 rpm [56]. Ampicillin a
standard drug of 1% is used as a positive control for antibacterial activity and blank was prepared
by adding only 1μl/ml culture to the broth and it served as a negative control. MIC values of
different compounds were noted by comparing the growth turbidity in tubes. A specific
concentration of compound where the bacterial growth inhibition has started is termed as a
minimal concentration of compound required for bacterial inhibition.
4
.2.2. Anti-fungal activity
The anti-fungal activities of the synthesized compounds were tested against filamentous fungi
Aspergillus niger MTCC 404 and Saccharomyces cerevisiae MTCC 1344 yeast cultures [58].
They were obtained from the Culture Collection Division at Department of Microbiology,
Osmania University. The fungal cultures were grown on yeast extract agar (YEP) media
containing chloramphenicol (50 μg/mL) for 2-4 days at 28 °C. After 2 days, the black spores and
lawn of cultures were collected and stored in an aqueous solution of 40% (v/v) glycerol at -80
°
C. Anti-fungal assay can be done by cylinder plate, disc method, cross streak plate method, and
broth dilution method. Here in the current study we used cross steak plate method to identify the
minimum concentration of compound required to inhibit the fungal growth.YEP agar media
(commonly used to assess susceptibility of diverse mutants) was prepared by mixing the
bactopeptone, sodium chloride and maintained final pH 7 at 25°C. Sterilization of media is
0
carried out at 121 C/15 lbs pressure for 30 minutes, and cooled to room temperature and poured
into sterile petriplates. Aqueous cultures of fungal strains were spreaded evenly on plates and
different concentrations of diluted compounds were streaked on plate. The measurement of clear
zonal area length (mm) on YEP agar plate determined the compound efficacy for fungal growth
inhibition.
4
.2.3. Antioxidant activity
DPPH assay is one of the most widely used method for testing free radical scavenging activity
62-63]. The UV spectrophotometric assay proposed by Yen and Chen in 1995 [64], determines
the antioxidant ability of synthesized compounds. It uses stable light sensitive freshly prepared
.5 mM DPPH dissolved in methanol as a reagent solution. Standard and other synthesized
[
0
compounds at various concentrations were successively prepared from 1 mM stock by dissolving
in DMSO. Antioxidant activity of diluted test compounds was checked by transferring various
concentrations from 10 μM to 200 μM.100 μl of DPPH• reagent was transferred constantly to
tube and
1
. Sterile distilled water was added to tube to make up to 1 ml. The mixture was shook gently and
permitted to stand in dark at room temperature for 30 minutes. Blank solution was prepared by
adding various concentrations of compound diluents and constant amount of reagent solution to
make up to 1000 ml.

2
. Ascorbic acid a well known stable antioxidant of 1 mM stock diluted in DMSO was used as a
positive control for maintenance.
3
4
. All determinations for each concentration were carried in triplicates to avoid mean variations.
. Absorbance of solutions was measured by using UV spectrophotometer at 517 nm. The plotted
by taking concentrations of the compound in x-axis and absorbance at 517 nM in y-axis
showed the percent antioxidant activity of samples.
The free radical scavenging activity was calculated using the following equation:
%
Antiradical activity= [(Control abs - Sample abs) / Control abs] x100
The standard curve was linear between 10 and 200 μM concentrations and the results of Table –
listed compounds at 517 nM were expressed as % antioxidant activity at various molecular
concentrations.
3
4
.3. Molecular docking
The structures of all the synthesized compounds were generated using MarvinSketch 5.6.0.2.
1998-2011, Copyright © ChemAxon Ltd), cleaned in 3D and saved in .pdb format for docking
(
studies. The PDB file of the target protein downloaded from RCSB PDB (www.rcsb.org), PBP
co-crystal structures (PDB ID: 3HUN & 3ITA). Docking was performed with Molegro Virtual
Docker (MVD 2012.5.5) [65]. While docking first the protein and ligands were prepared by
assigning bonds, bond orders, charges, explicit hydrogens, flexible torsions in ligands if they
were missing as per manual instructions. Possible binding sites were detected for both PBP’s,
first cavity in 3HUN and third cavity in 3ITA were used respectively. The search algorithm is
taken as Mol Dock SE and number of runs are taken as 10 and max iterations were 1500 with
population size 50 and with an energy threshold of 100. Further investigations of the binding
interactions of the most active docked compounds were performed using Biovia discovery studio
2
020 Client and PyMol.
5
. Acknowledgement:
The authors thank The Heads of Dept. of Chemistry, Nizam College and Osmania University,
Hyderabad, for providing lab-facilities. KRA, SB, grateful to UGC for Grant and Fellowship
respectively and RD grateful to RGNF. SSR also thanks SERB (ECR/2017/003381) for financial
support. The authors thank Team Analytical, CFRD for analytical support.

6
. Supplementary:
1
13
H NMR, C NMR, MASS and IR data for all compounds provided with supplementary.
7
. Conflict Interest:
The authors hereby declare no conflict of interest.
8
. References:
[
1] IACG, Report to the Secretary-General of the United Nations, April-2019.
https://www.un.org/securitycouncil/content/reports-submitted-transmitted-secretary-general-
th
security-council-2019. (Accessed on 27 December, 2019).
[
2] WorldHealth
Organization,
Global
Action
Plan
on
Anti-microbial
Resistance.
http://www.wpro.who.int/entity/drug_resistance/resources/global_action_plan-eng.pdf. (Accessed
th
on 27 December, 2019) ISBN: 9789241509763.
[
[
[
3] L. FD, Is Staphylococcus aureus an intracellular pathogen., Trends Microbiol, 8 (1998) 341-344.
4] B. WJ, A case of pathogenicity of Bacillus subtilis, J Infect Dis 40 (1927) 313-315.
5] H. Ochman, R .K. Selander, Standard reference strains of Escherichia coli from natural
populations, J Bacterial, 157 (1984) 690-693.
[
6] S. Agarwal, S. Cammerer, S. Filali, W. Frohner, J. Knoll, M.P. Krahl, K.R. Reddy, H.-J. Knolker,
Curr Org Chem 9 (2005) 1601-1614.
[
[
[
[
[
[
7] J.F. Gonzaález, I. Ortín, E. de la Cuesta, J. C. Menéndez, Chem Soc Rev 41 (2012) 6902-6905.
8] E. Brown, Ring Nitrogen and Key Biomolecules, (1998) Kluwer Academic Press.
9] Y. Shirota, J Mater Chem 10 (2000) 1-25.
10] Z. Jin, Nat Prod Rep 20 (2003) 584-605.
11] J. H, Boyer, Heterocyclic Compounds (R C Elder field, ed). 7 (1961) 525.
12] Nagaraj, K.C. Chaluvaraj, M.S. Niranjan, S. Kiran, 1,3,4-Oxa-Diazole: A Potent Drug Candidate
With Various Pharmacological Activities, International Journal of Pharmacy and Pharmaceutical
Sciences, 3 (2011) 9-16.
[
[
[
13] A. Almasirad, S.A. Tabatabai, M. Faizi, A. Kebriaeezadeh, N. Mehrabi, A. Dalvandi, A. Shafiee,
Synthesis and anticonvulsant activity of new 2-substituted-5-[2-(2-fluorophenoxy)phenyl]-1,3,4-
oxadiazoles and 1,2,4-triazoles, Bioorganic & Medicinal Chemistry Letters, 14 (2004) 6057-6059.
14] S. Ameen, M.S. Akhtar, H.-K. Seo, H.S. Shin, An electrochemical sensing platform based on
hollow mesoporous ZnOnanoglobules modified glassy carbon electrode: Selective detection of
piperidine chemical, Chemical Engineering Journal, 270 (2015) 564-571.
15] J. Janardhanan, M. Chang, S.Mobashery, The Oxadiazole antibacterials, Curr Opin Microbiol 33
(
2016) 13-17
[
[
16] A. Pace, A. P.Pierro, The new era of 1,2,4-oxadiazoles. OrgBiomol Chem, 7 (2009) 4337-4348.
17] M, Ogata, H, Atobe, H, K, Kushido , In vitro sensitivity of mycoplasmas isolated from various
animals and sewage to antibiotics and nitrofurans., J. Antibiot. , 24 (1971) 443-451.
[
18] H. Gadegoni, S. Manda, Synthesis and screening of some novel substituted indoles contained 1,3,4-
oxadiazole and 1,2,4-triazole moiety, Chinese Chemical Letters, 24 (2013) 127-130.

[
19] R. Aziz ur, A. Siddiqa, M.A. Abbasi, S. Rasool, S.Z. Siddiqui, I. Ahmad, S. Afzal, Synthesis of
some new 5-substituted-2-((6-chloro-3,4-methylenedioxyphenyl)methylthio)-1,3,4-oxadiazole
derivatives as suitable antibacterial inhibitors, Bulletin of Faculty of Pharmacy, Cairo University,
5
3 (2015) 37-43.
[
[
20] S. Bondock, H. Etman, F. Badria, Synthesis and Antitumor Evaluation of Some New 1,3,4-
Oxadiazole-Based Heterocycles, ChemInform, 43 (2012).
21] Salahuddin, M. Shaharyar, A. Mazumder, M.J. Ahsan, Synthesis, characterization and anticancer
evaluation of 2-(naphthalen-1-ylmethyl/naphthalen-2-yloxymethyl)-1-[5-(substituted phenyl)-
[
1,3,4]oxadiazol-2-ylmethyl]-1H-benzimidazole, Arabian Journal of Chemistry, 7 (2014) 418-424.
[
[
[
[
22] N.D. James, J.W. Growcott, The Specific Endothelin A Receptor Antagonist ZD4054: Preclinical
and Clinical Results, European Urology Supplements, 8 (2009) 29-35.
23] S. Vardan, H. Smulyan, S. Mookherjee, R. Eich, Effects of tiodazosin, a new antihypertensive,
hemodynamics and clinical variables, Clinical Pharmacology & Therapeutics, 34 (1983) 290-296.
24] R. Schlecker, P.C. Thieme, The synthesis of antihypertensive 3-(1,3,4-oxadiazol-2-
yl)phenoxypropanolahines, Tetrahedron, 44 (1988) 3289-3294.
25] P.A. Summa V, Bonelli F, Crescenzi B, Donghi M, Ferrara M, Fiore F, Gardelli C, Gonzalez Paz
O, Hazuda DJ, Jones P, Kinzel O, Laufer R, Monteagudo E, Muraglia E, Nizi E, Orvieto F, Pace P,
Pescatore G, Scarpelli R, Stillmock K, Witmer MV, Rowley M., Discovery of raltegravir, a potent,
selective orally bioavailable HIV-integrase inhibitor for the treatment of HIV-AIDS infection.,
Journal of Medicinal Chemistry, 18 (2008) 5843-5855.
[
[
[
[
[
[
[
26] K. Manjunatha, B. Poojary, P.L. Lobo, J. Fernandes, N.S. Kumari, Synthesis and biological
evaluation of some 1,3,4-oxadiazole derivatives, European Journal of Medicinal Chemistry, 45
(
2010) 5225-5233.
27] K.K. Jha, A. Samad, Y. Kumar, M. Shaharyar, R.L. Khosa, J. Jain, V. Kumar, P. Singh, Design,
synthesis and biological evaluation of 1,3,4-oxadiazole derivatives, Eur J Med Chem, 45 (2010)
4
963-4967.
28] S.J. Gilani, S.A. Khan, N. Siddiqui, Synthesis and pharmacological evaluation of condensed
heterocyclic 6-substituted 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole and 1,3,4-oxadiazole derivatives
of isoniazid, Bioorg Med Chem Lett, 20 (2010) 4762-4765.
29] M.I. Mohamed, N.G. Kandile, H.T. Zaky, Synthesis and Antimicrobial Activity of 1,3,4-
Oxadiazole-2(3H)-thione and Azidomethanone Derivatives Based on Quinoline-4-carbohydrazide
Derivatives, Journal of Heterocyclic Chemistry, 54 (2017) 35-43.
30] N.C. Desai, A.M. Dodiya, K.M. Rajpara, Y.M. Rupala, Synthesis and antimicrobial screening of
1
2
,3,4-oxadiazole and clubbed thiophene derivatives, Journal of Saudi Chemical Society, 18 (2014)
55-261.
31] E. Palaska, G. Sahin, P. Kelicen, N.T. Durlu, G. Altinok, Synthesis and anti-inflammatory activity
of 1-acylthiosemicarbazides, 1,3,4-oxadiazoles, 1,3,4-thiadiazoles and 1,2,4-triazole-3-thiones,
Farmaco, 57 (2002) 101-107.
32] M. Amir, K. Shikha, Synthesis and anti-inflammatory, analgesic, ulcerogenic and lipid peroxidation
activities of some new 2-[(2,6-dichloroanilino) phenyl]acetic acid derivatives, Eur J Med Chem, 39
(
2004) 535-545.

[
[
33] Z. Hajimahdi, A. Zarghi, R. Zabihollahi, M.R. Aghasadeghi, Synthesis, biological evaluation, and
molecular modeling studies of new 1,3,4-oxadiazole- and 1,3,4-thiadiazole-substituted 4-oxo-4H-
pyrido[1,2-a]pyrimidines as anti-HIV-1 agents, Medicinal Chemistry Research, 22 (2013) 2467-
2
475.
34] T.J. Tucker, J.T. Sisko, R.M. Tynebor, T.M. Williams, P.J. Felock, J.A. Flynn, M.T. Lai, Y. Liang,
G. McGaughey, M. Liu, M. Miller, G. Moyer, V. Munshi, R. Perlow-Poehnelt, S. Prasad, J.C. Reid,
R. Sanchez, M. Torrent, J.P. Vacca, B.L. Wan, Y. Yan, Discovery of 3-{5-[(6-amino-1H-
pyrazolo[3,4-b]pyridine-3-yl)methoxy]-2-chlorophenoxy}-5-chloro benzonitrile (MK-4965):
a
potent, orally bioavailable HIV-1 non-nucleoside reverse transcriptase inhibitor with improved
potency against key mutant viruses, J Med Chem, 51 (2008) 6503-6511.
[
[
35] D. Sriram, D. Banerjee, P. Yogeeswari, Efavirenz Mannich bases: Synthesis, anti-HIV and
antitubercular activities, Journal of Enzyme Inhibition and Medicinal Chemistry, 24 (2009) 1-5.
36] N. Karal, A. Gürsoy, F. Kandemirli, N. Shvets, F.B. Kaynak, S. Özbey, V. Kovalishyn, A.
Dimoglo, Synthesis and structure–antituberculosis activity relationship of 1H-indole-2,3-dione
derivatives, Bioorganic & Medicinal Chemistry, 15 (2007) 5888-5904.
[
[
[
[
37] J.T. Palmer, B.L. Hirschbein, H. Cheung, J. McCarter, J.W. Janc, Z.W. Yu, G. Wesolowski, Keto-
1
2
,3,4-oxadiazoles as cathepsin K inhibitors, Bioorganic & Medicinal Chemistry Letters, 16 (2006)
909-2914.
38] M.T.H. Khan, M.I. Choudhary, K.M. Khan, M. Rani, R. Atta ur, Structure–activity relationships of
tyrosinase inhibitory combinatorial library of 2,5-disubstituted-1,3,4-oxadiazole analogues,
Bioorganic & Medicinal Chemistry, 13 (2005) 3385-3395.
39] S. Ke, Z. Li, X. Qian, 1,3,4-Oxadiazole-3(2H)-carboxamide derivatives as potential novel class of
monoamine oxidase (MAO) inhibitors: Synthesis, evaluation, and role of urea moiety, Bioorganic
&
Medicinal Chemistry, 16 (2008) 7565-7572.
40] E. Maccioni, S. Alcaro, R. Cirilli, S. Vigo, M.C. Cardia, M.L. Sanna, R. Meleddu, M. Yanez, G.
Costa, L. Casu, P. Matyus, S. Distinto, 3-Acetyl-2,5-diaryl-2,3-dihydro-1,3,4-oxadiazoles: A New
Scaffold for the Selective Inhibition of Monoamine Oxidase B, Journal of Medicinal Chemistry, 54
(
2011) 6394-6398.
[
[
41] M. Verma, S.N. Pandeya, K.N. Singh, J.P. Stables, Anticonvulsant activity of Schiff bases of isatin
derivatives, Acta pharmaceutica (Zagreb, Croatia), 54 (2004) 49-56.
42] A.M.M.E. Omar, O.M. Aboulwafa, Synthesis and anticonvulsant properties of a novel series of 2-
substituted amino-5-aryl-1,3,4-oxadiazole derivatives, Journal of Heterocyclic Chemistry, 21
(
1984) 1415-1418.
[
[
43] A. Almasirad, S.A. Tabatabai, M. Faizi, A. Kebriaeezadeh, N. Mehrabi, A. Dalvandi, A. Shafiee,
Synthesis and anticonvulsant activity of new 2-substituted-5- [2-(2-fluorophenoxy)phenyl]-1,3,4-
oxadiazoles and 1,2,4-triazoles, Bioorg Med Chem Lett, 14 (2004) 6057-6059
44] H.L. Yale, K. Losee, 2-amino-5-substituted 1,3,4-oxadiazoles and 5-imino-2-substituted delta-2-
1
,3,4-oxadiazolines. A group of novel muscle relaxants, J Med Chem, 9 (1966) 478-483.
[
[
45] N. D. James, J.W. Growcott, Drugs Future 34 (2009) 624-634.
46] H. Tomkinson, J. Kemp, S. Oliver, H. Swaisland, M. Taboada, T. Morris, BMC Clin Pharmacol 11
(
2011) 3-11.

[
47] C. Athanassopoulos, L.B. Auerbach, D. Bauer, R. D. Bolton, R. L. Burman, I. Cohen, D. O.
Caldwell, B. D. Dieterle, J. B. Donahue, A. M. Eisner, A. Fazely, F. J. Federspiel, M. Gray, G. T.
Garvey, R. M Guanasingha, V. Highland, R. Imlay, K. Johnston, H. J. Kim, W. C. Louis, A. Lu, J.
Margulies, G. B. Mills, K. McIlhany, W. Metcalf, R. A. Reeder, V. Sandberg, M. Schillaci, D.
Smith, I. Stancu, W. Strossman, R. Tayloe, G. J. VanDalen, W. Vernon, Y.-X, Wang, D. H. White,
D. Whitehouse, D. Works, Y. Xiao, S. Yellin, NuclInstrum Meth A 388: 149.
[
[
[
48] N.A. Siddiqui, Waquar; Alam, M. Shamsher; Ali, Ruhi; Jain, Sanjay; Azad, Bishmillah; Akhtar,
Jawaid, Triazoles: as potential bioactive agents, International Journal of Pharmaceutical Sciences
Review and Research, 8 (2011) 161-169.
49] C. Menendez, S. Gau, C. Lherbet, F. Rodriguez, C. Inard, M.R. Pasca, M. Baltas, Synthesis and
biological activities of triazole derivatives as inhibitors of InhA and antituberculosis agents, Eur J
Med Chem, 46 (2011) 5524-5531.
50] C. Gill, G. Jadhav, M. Shaikh, R. Kale, A. Ghawalkar, D. Nagargoje, M. Shiradkar, Clubbed [1,2,3]
triazoles by fluorine benzimidazole: a novel approach to H37Rv inhibitors as a potential treatment
for tuberculosis, Bioorg Med Chem Lett, 18 (2008) 6244-6247.
[
[
51] S. Kim, S.N. Cho, T. Oh, P. Kim, Design and synthesis of 1H-1,2,3-triazoles derived from
econazole as antitubercular agents, Bioorg Med Chem Lett, 22 (2012) 6844-6847.
52] B. Zhou, Y. He, X. Zhang, J. Xu, Y. Luo, Y. Wang, S.G. Franzblau, Z. Yang, R.J. Chan, Y. Liu, J.
Zheng, Z.Y. Zhang, Targeting mycobacterium protein tyrosine phosphatase B for antituberculosis
agents, Proceedings of the National Academy of Sciences of the United States of America, 107
(
2010) 4573-4578.
53] N.U. Sahu, V. Singh, D.M. Ferraris, M. Rizzi, P.S. Kharkar, Hit discovery of Mycobacterium
tuberculosis inosine 5 -monophosphate dehydrogenase, GuaB2, inhibitors, Bioorganic & Medicinal
[
[
′
Chemistry Letters, 28 (2018) 1714-1718.
54] F.A. Mandl, V.C. Kirsch, I. Ugur, E. Kunold, J. Vomacka, C. Fetzer, S. Schneider, K. Richter, T.M.
Fuchs, I. Antes, S.A. Sieber, Natural-Product-Inspired Aminoepoxybenzoquinones Kill Members of
the Gram-Negative Pathogen Salmonella by Attenuating Cellular Stress Response, Angewandte
Chemie (International ed. in English), 55 (2016) 14852-14857.
[
55] Standard approved methods from Clinical and Laboratory Standards Institute (CLSI).AnnetteW.
Fothergill http://www.bookmetrix.com/detail/chapter/d959dad1-472e-4037-af15-
th
a93397de56b7#citations.(Accessed on 27 December, 2019).
[
[
56] RohitAGokarn, & Gokarn, Rohit & Patgiri, Biswajyoti & PKPrajapati,. (2015). Antimicrobial study
of Shadguna Rasa Sindura. Journal of Indian System of Medicine. 3. 136-140.
57] J. Iqbal, R. Siddiqui, S.U. Kazmi, and N. A. Khan1. A Simple Assay to Screen Antimicrobial
Compounds Potentiating the Activity of Current Antibiotics. Biomed Res Int. 2013 (2013) 927323
-327.
[
[
58] M. Araia, H. Tomodaa, T. Okudab, H. Wangc, N.Tabataa, R. Masumaa, Y.Yamaguchia ,and S.
Omura. Funicone-Related Compounds, Potentiators Of Antifungal Miconazole Activity, Produced
By Talaromy, The J. of Antibiotics 55 (2002) 172-180
59] Zhou, Huan-Xiang, and Xiaodong Pang. “Electrostatic Interactions in Protein Structure, Folding,
Binding, and Condensation.” Chemical Reviews vol. 118,4 (2018) 1691-1741.

[
60] V. Navratna, S.Nadig, V. Sood, K. Prasad, G. Arakere, and B. Gopal. Molecular Basis for the Role
of Staphylococcus aureus Penicillin Binding Protein 4 in Antimicrobial Resistance , Journal of
Bacteriology, 192 ( 2010) 134–144.
[
[
[
[
[
61] Y. Chen, W. Zhang, Q. Shi, D. Hesek, M. Lee, S. Mobashery, B. K. Shoichet, Crystal Structures of
Penicillin-Binding Protein 6 from Escherichia coli J Am Chem Soc. 131 (2009) 14345–14354.
62] O.P.B. Sharma, T.K. , DPPH Antioxidant Assay Revisited, Food Chemistry, 113 (2009) 1202-
1
205.
63] Y.K. Al-Majedy, A.A. Al-Amiery, A.A.H. Kadhum, A.B. Mohamad, Antioxidant Activities of 4-
Methylumbelliferone Derivatives, Plos One, 11 (2016) e0156625.
64] G.-C. Yen, H.-Y. Chen, Antioxidant Activity of Various Tea Extracts in Relation to Their
Antimutagenicity, Journal of Agricultural and Food Chemistry, 43 (1995) 27-32.
65] R. Thomsen, “MolDock: a new technique for high-accuracy molecular docking,” Journal of
medicinal chemistry, 49 (2006) 3315-3321.

9
. Figures and legends:
5a
5b
5c
5d
Figure -5: 5a & b represents Docked 2D image of compound 8p & 8q with Penicillin binding
protein 4 (PBP4) (PDB ID: 3HUN); 5c & d represents 3D-stick enlarged view of compound 8p
and 8q with 3HUN (Ribbons). The green dotted lines in the figure represent the hydrogen
bonding between the ligand and protein. Different protein ligands are stabilized by different
interactions and color codes are given in the bottom of figure 1a and 1b.

6a
6b
6d
6c
Figure -6: Docked 2D image of compound 8p & 8q (6a & 6b) with Penicillin binding protein 6
PBP6) (PDB ID: 3ITA); 6c & d represents 3D-stick enlarged view of compound 8p and 8q
(
with 3ITA (Ribbons). The green dotted lines in the figure represent the hydrogen bonding
between the ligand and protein.