Synthesis and antimicrobial activity of piperine analogues containing 1,2,4-triazole ring

Article abstract of DOI:10.14233/ajchem.2019.21876

A series 1,2,4-triazole piperine analogues (TP1-TP6) were designed and synthesized. The structures were confirmed using ¹H NMR and ¹³C NMR. Antibacterial study was done using Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram-negative microorganisms (E. coli and Pseudomonas aeruginosa) by disc diffusion method. Compound containing chloro substitution (TP6) showed the highest effect, while compound TP1, TP3, TP4, TP5 showed the moderate activity.

Full text of DOI:10.14233/ajchem.2019.21876

Asian Journal of Chemistry; Vol. 31, No. 5 (2019), 1077-1080
A
SIAN
J
OURNAL OF HEMISTRY
C
https://doi.org/10.14233/ajchem.2019.21876
Synthesis and Antimicrobial Activity of Piperine Analogues Containing 1,2,4-Triazole Ring
1
1
2
3,*
KOTTAKKI NAVEEN KUMAR , KARTEEK RAO AMPERAYANI , V. RAVI SANKAR UMMDI and UMA DEVI PARIMI
1Department of Chemistry, GITAM University, Visakhapatnam-530045, India
2Molecular Biology Division, MicGene Lab, Visakhapatnam-530017, India
3Department of Chemistry, Gayatri Vidya Parishad College for Degree and P.G. Courses (A), Visakhapatnam-530045, India
*Corresponding author: E-mail: umadevichemistry@gmail.com
Received: 14 December 2018;
Accepted: 29 December 2018;
Published online: 28 March 2019;
AJC-19333
A series 1,2,4-triazole piperine analogues (TP1-TP6) were designed and synthesized. The structures were confirmed using 1H NMR and
13C NMR. Antibacterial study was done using Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram-negative micro-
organisms (E. coli and Pseudomonas aeruginosa) by disc diffusion method. Compound containing chloro substitution (TP6) showed the
highest effect, while compound TP1, TP3, TP4, TP5 showed the moderate activity.
Keywords: Piperine-triazole analogues, Antimicrobial activity.
Piperine and its analogs are also one of the major com-
pounds possess potent antibacterial activity [11,12]. The study
of Kumar et al. [13] demonstrate that piperine analogs are
inhibit the NorA pump of Staphylococcus aureus. There is no
earlier reports on hybrid piperine analogues with 1,2,4-tria-
zoles. In this point of view, the present study was aimed to
synthesize novel piperine-1,2,4-triazoles analogues and their
antibacterial activity evaluation.
INTRODUCTION
Black pepper (Piper nigrum) is one of the important medi-
cinal plants grown around southAsia region with various biolo-
gical activities [1], piperine is hydrophobic amide alkaloid
present in piper nigrum which is responsible for the pungency
of pepper [2-4]. Literature survey reveals that piperine possess
various biological activities such as with potent antibacterial
activity either individually [5] or in combination with mupi-
rocin [6], antioxidant activity [7] and anti-inflammatory activity
[8].
As the need increased for identification of new biological
active molecules against emerging microbial infections,
researchers synthesizing new active compounds from natural
compounds as precursors or their derivatives or combining
two active molecules into new bioactive (hybrid or conjugate)
molecules [9,10]. This type of new molecules possess more
potent biological activity in curing different diseases com-
pared to their parent molecules [10]. 1,2,4-Triazole nucleus is
stable when it incorporated into biologically active molecules
increases their pharmacological activity. The previous studies
on 1,2,4-triazole derivatives such as 1,2,4-triazoles-5-thione,
1,3,4-thiadiazole, 1,3-thiazolan-4-one possess antibacterial
activity [9,10].
EXPERIMENTAL
The solutions/reagents used in the current research were
of analytical grade. The synthesized compounds confirmed
through their structural elucidation using 1H NMR (Bruker),
13C NMR and IR their melting points (Fisher-Johns apparatus)
and their retention times using thin layer chromatography.
Synthesis of piperic acid: The was prepared using 0.118
mol of piperine and 20 % EtOH-KOH (300 mL) for 10 h reflux
and then washed with ethanol (99 % purity). The potassium
piperate was then treated with 0.1 M HCl and then washed
with distilled water (Scheme-I). Then piperic acid (yellow
colour) was recrystallized with ethanol.
Synthesis of triazoles: Substituted benzoic acid (0.01
mol) in 0.2 mol of anhydrous methanol and 0.5 mL of conc.
H2SO4 was added in a round bottom flask and then refluxed
This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike
4.0 (CC BY-NC-SA 4.0) International License which allows readers to freely read, download, copy, distribute, print, search, or link to the full
texts of its articles and to use them for any other lawful non-commercial purpose as long as the original source is duly acknowledged.

1078 Kumar et al.
Asian J. Chem.
O
for column chromatography to isolate pure compounds using
hexane and ethyl acetate mixture as mobile phase (Scheme-
III).
Ethanolic KOH
Reflux
O
O
N
HO
O
O
Conc. HCl
O
Scheme-I
O
N
N
O
O
HO
SH
+
N
for 5 h. The resultant compound was confirmed by TLC
(hexane:ethyl acetate) in the ratio 80:20 and then required
compound was isolated by treating with NaOH. Then 0.01
mol of substituted methyl benzoate in 25 mL of ethanol was
taken in a round bottom flask. The solution was refluxed for
4 h by adding 0.7 mL of 0.15 mol N2H4. The product was
confirmed by TLC (hexane:ethyl acetate) in the ratio 80:20
and distilledoff ethanol and it is cooled in ice water. The
resultant compound was recrystallized with EtOH (78 % yield).
Potassium 2-benzoylhyrazinecarbodithioate precipitate
was prepared from mixture of 8.5 g of KOH (1.20 mol) in 125
mL C2H5OH, 1.36 g of benzoic acid hydrazide (0.08 mol) and
14.5 mL of carbon disulphide (1.52 mol) by reacting with 250
mL anhydrous ether. The prepared precipitate was filtered by
washing with diethyl ether. The potassium salt was obtained
from filtrate after drying. Then, the mixture of 4.44 g (0.21
mol) potassium salt (2-benzoylhydrazine carbodithioate), 2
mL of hydrazine hydrate (0.5 mol) in 80 mL water was refluxed
for 3 h, then a homogenous solutions formed after release of
hydrogen sulphide and the colour of solution will turn to green.
Then solution was precipitated using cold water, after
precipitation acidification was carried using conc. HCl. Then,
solution was filtered by washing with cold water. Then, final
product was recrystallized using EtOH (Scheme-II).
Synthesis of piperine analogs: Piperic acid (1.98 g) was
dissolved in dimethyl formamide at 0-5 °C, then added 2-(1H-
benzotriazol-1-yl)-1,1,13,3-tetramethyluronium hexa-
fluorophosphate (HBTU) and was continuously stirred for 30
min. After the homogenous mixture formation, added 2.6 mL
N,N-diisopropyl ethylamine, 1.98 g of 4-amino-5-phenyl-4H-
1,2,4-triazole-3-thiol (0.51 mol). After addition, the tempera-
ture was raised to room temperature and mixture was stirred
continuously for 5 h at room temperature. The product for-
mation was monitored simultaneous application of TLC (6:4
ratio of hexane and ethyl acetate as mobile phase). After the
crude compound formation, it was washed separately with HCl
and then NaOH. Then crude extract was concentrated and used
R
H2N
(2E,4E)-5-(Benzo[d][1,3]dioxol-
5-yl)penta-2,4-dienoic acid
4-Amino-5-phenyl-4H-
1,2,4-triazole-3-thiol
DMF
HBTU
DIPEA
O
O
O
HN
N
SH
N
N
R
(2E,4E)-5-(Benzo[d][1,3]dioxol-5-yl)-N-(3-mercapto-5-
phenyl-4H-1,2,4-triazol-4-yl)penta-2,4-dienamide
Scheme-III
Spectral data
(2E,4E)-5-(Benzo[d][1,3]dioxol-5-yl)-N-(3-mercapto-5-
phenyl-4H-1,2,4-triazol-4-yl)penta-2,4-dienamide (TP1):
m.f. C20H16N4O3S, m.w. 392.09, m.p. 167-172 °C. IR (KBr,
ν
max, cm–1): 943 (N-C-S str), 3085 (CH=CH str), 1690 (C=O
str), 2500 (SH str), 3539 (NH str), 1550 (C=N str), 1352 (C-N
str), 698 (C-S str), 1278 (NN- C str). 1H NMR amide N-H δ
8.21 (s, 1H), (triazole Ar-H δ 7.45-8.02 (m, 5H), -S-H δ-4.80
(s, 1H), piperine (C=CH) δ 6.06 (d, 1H), δ -7.28 (t, 1H), δ
6.73 (t, 1H), δ -6.75 (d, 1H)), Ar-H δ 6.75-7.03 (m, 3H), O-
CH2 δ -5.96 (s, 2H), 13C NMR (125 MHz, common NMR
solvents) δ 167.87, 164.40, 154.26, 147.51, 147.42, 141.62,
138.85, 130.28, 129.41, 129.06, 127.30, 125.79, 124.73,
123.17, 119.59, 108.53, 106.92, 101.01.
(2E,4E)-5-(Benzo[d][1,3]dioxol-5-yl)-N-(3-(3,5-dinitro-
phenyl)-5-mercapto-4H-1,2,4-triazol-4-yl)penta-2,4-
dienamide (TP2): m.f. C20H14N6O7S, m.w. 482.06, m.p. 260-
266 °C. IR (KBr, νmax, cm–1): 943 (N-C-S str), 3085 (CH=CH
str), 1690 (C=O str), 2500 (SH str), 3539 (NH str), 1550 (C=N
COOCH3
COOH
O
NH2-NH2
CS2/KOH
MeOH
NH2
MeOH
C
N
H
R
Conc H2SO4
R
R
substitued benzohydrazide
substituted methyl benzoate
substituted benzoic acid
N
N
O
H
NH2-NH2
N
S
C
SH
NH
N
C
K
R
H2N
R
S
4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol
potassium 2-benzoylhydrazinecarbodithioate
R= H, m-NO2, p-CH3O, p-OH, p-NO2, p-Cl
Scheme-II

Vol. 31, No. 5 (2019)
Synthesis and Antimicrobial Activity of Piperine Analogues Containing 1,2,4-Triazole Ring 1079
str), 1352 (C-N str), 698 (C-S str), 1276 (NN- C str). 1H NMR
amide N-H δ 8. 32 (s, 1H) triazole 3,5-nitro Ar-H δ 8.79-8.88
(m, 3H), -S-H δ-4.57 (s, 1H), piperine (C=CH) δ 6.06 (d, 1H),
δ -7.28 (t, 1H), δ 6.73 (t, 1H), δ -6.75 (d, 1H)), Ar-H δ 6.75-
7.03 (m, 3H), O-CH2 δ -5.96 (s, 2H), 13C NMR (125 MHz,
common NMR solvents) δ 167.90, 164.40, 153.86, 147.51,
147.42, 146.87, 141.62, 138.85, 129.41, 128.01, 125.79,
124.73, 123.17, 120.33, 119.59, 108.53, 106.92, 101.01.
(2E,4E)-5-(Benzo[d][1,3]dioxol-5-yl)-N-(3-mercapto-5-
(4-methoxyphenyl)-4H-1,2,4-triazol-4-yl)penta-2,4-
dienamide (TP3): m.f. C21H18N4O4S, m.w. 422.1, m.p. 154-
160 °C. IR (KBr, νmax, cm–1): 943 (N-C-S str), 3030 (CH=CH
str), 1698 (C=O str), 2500 (SH str), 3530 (NH str), 1550 (C=N
str), 1354 (C-N str), 698 (C-S str). 1H NMR amide N-H δ 8.15
(s, 1H) triazole 4-methoxy Ar-H δ 7.09-7.79 (m, 4H), -O-CH3
δ-3.79 (s, 1H), -S-H δ-4.80 (s, 1H), piperine (C=CH) δ 6.06
(d, 1H), δ -7.28 (t, 1H), δ 6.73 (t, 1H), δ -6.75 (d, 1H)), Ar-H
δ 6.75-7.03 (m, 3H), O-CH2 δ -5.96 (s, 2H), 13C NMR (125
MHz, common NMR solvents) δ 167.87, 164.40, 160.77,
154.06, 147.51, 147.42, 141.62, 138.85, 129.41, 126.10,
125.79, 123.17, 121.15, 119.59, 114.31, 108.53, 106.92,
101.01, 55.32.
(2E,4E)-5-(Benzo[d][1,3]dioxol-5-yl)-N-(3-(4-
hydroxyphenyl)-5-mercapto-4H-1,2,4-triazol-4-yl)penta-
2,4-dienamide (TP4): m.f. C20H16N4O4S, m.w. 408.43, m.p.
177-182 °C. IR (KBr, νmax, cm–1): 943 (N-C-S str), 3109 (ArCH
str), 1689 (C=O str), 2500 (SH str), 3542 (NH str), 1550 (C=N
str), 1359 (C-N str), 698 (C-S str). 1H NMR amide N-H δ 8.10
(s, 1H) triazole 4-hydroxy Ar-H δ 6.93-7.65 (m4H), -O-H δ-
7.60 (s, 1H), -S-H δ-4.80 (s, 1H), piperine (C=CH) δ 6.06 (d,
1H), δ -7.28 (t, 1H), δ 6.73 (t, 1H), δ -6.75 (d, 1H)), Ar-H δ
6.75-7.03 (m, 3H), O-CH2 δ -5.96 (s, 2H), 13C NMR (125 MHz,
common NMR solvents) δ 167.87, 164.40, 153.92, 150.65,
147.51, 147.42, 141.62, 138.85, 129.41, 126.48, 125.79,
123.17, 119.59, 119.45, 116.45, 108.53, 106.92, 101.01.
(2E,4E)-5-(Benzo[d][1,3]dioxol-5-yl)-N-(3-mercapto-5-
(4-nitrophenyl)-4H-1,2,4-triazol-4-yl)penta-2,4-dienamide
(TP5): m.f. C20H15N5O5S, m.w. 437.08, m.p. 235-241 °C. IR
(KBr, νmax, cm–1): 943 (N-C-S str), 3106 (ArCHstr), 1694 (C=O
str), 2500 (SH str), 3540 (NH str), 1550 (C=N str), 1345 (C-N
str), 698 (C-S str). 1H NMR amide N-H δ 8.33 (s, 1H) triazole
4-nitro Ar-H δ 8.01-8.30 (m, 4H), -S-H δ-4.80 (s, 1H), piperine
(C=CH) δ 6.06 (d, 1H), δ -7.28 (t, 1H), δ 6.73 (t, 1H), δ -6.75
(d, 1H)), Ar-H δ 6.75-7.03 (m, 3H), O-CH2 δ -5.96 (s, 2H),
13C NMR (125 MHz, common NMR solvents) δ 167.87,
164.40, 154.26, 149.11, 147.51, 147.42, 141.62, 138.85,
132.44, 129.41, 125.79, 125.40, 124.45, 123.17, 119.59,
108.53, 106.92, 101.01.
common NMR solvents) δ 167.87, 164.40, 154.27, 147.51,
147.42, 141.62, 138.85, 137.86, 129.41, 129.22, 127.24,
126.49, 125.79, 123.17, 119.59, 108.53, 106.92, 101.01.
Antimicrobial activity
Two microorganisms viz. Bacillus subtilis MTCC211 and
Escherichia coli MTCC443 are used in the present study and
collected from MTCC, Chandigarh, India. Mueller Hinton
Agar medium to be used for routine susceptibility testing of
bacteria due to its acceptable reproducibility, satisfactory
growth of most pathogens [14].
Agar-well diffusion testing: The antibacterial activity was
assessed for the synthesized drugs using agar well diffusion
test method [15]. The method is basically on diffusion of the
desired drug in a vertical cylinder well in a agar petri plate,
which is pre-cultured with the testing bacterial strain. The
activity of the compounds will be measured using the formation
of zones around the wells [16,17]. In the current study, Muller-
Hinton agar was used to culture the test micro-organisms on
petri dishes.After solidification of agar, cotton swab was used
to spread the testing bacterial strains and then 6mm wells were
placed on agar plate with sterile steel borer. Then, 50 µL of
synthesized drugs (TP-1 to TP-6) were tested on selected bac-
teria using vancomycin as standard drug (30 µg) and dimethl
sulphoxide (DMSO) as vehicle. After, placing the test com-
pounds, standard, vehicle in wells placed the petri dishes aside
for 1 h without disturbance for diffusion of compounds in wells.
Then, plates were incubated for 24 h at 37 °C.After completion
of incubation, the plates were used to measure the zones of
inhibition around the wells using well reader (scale). The expe-
riment was repeated thrice and the results were expressed as
average in mm. Those compounds which were unable to exhibit
inhibition zone (inhibition zone diameter less than 7 mm) were
considered non-active.
RESULTS AND DISCUSSION
The titled compounds were successfully synthesized with
good percentage of yields and the reaction process were
showed in Scheme-III. The synthesized compounds were
confirmed by their analytical and spectral data.
The IR spectra peaks at 3300 and 1662 were corresponds
to N-H of amide and C=O to the produced compound from
methyl benzoate. The C-S stretch peaks at 698 cm-1 in IR spectra
confirms of the synthesized potassium 2-benzoylhydrazine-
1
carbodithioate compound. The IR and H NMR spectras of
4[amino]-5-phenyl-4H-1,2,4-triazole-3-thiol confirms its
structure by appearance of N-C-S stretch at 943 cm-1 and N-
C-C stretch peaks at 1278 cm-1 IR spectra and SH, NH peaks
at 4.80 δ and 8.21 δ in NMR spectra. The compound synthe-
sized from 4[amino]-5-phenyl-4H-1,2,4-triazole-3-thiol is
(2E,4E)-5-(benzo[d][1,3]dioxol-5-yl)-N-(3-mercapto-5-
phenyl-4H-1,2,4-triazol-4-yl)penta-2,4-dienamide is confir-
med by its IR spectra due to absence of NH peak and presence
of -N-N-C.
(2E,4E)-5-(Benzo[d][1,3]dioxol-5-yl)-N-(3-(4-
chlorophenyl)-5-mercapto-4H-1,2,4-triazol-4-yl)penta-2,4-
dienamide (TP6): m.f. C20H15N4O3SCl, m.w. 426.06, m.p. 185-
191 °C. IR (KBr, νmax, cm–1): 943 (N-C-S str), 3010 (Ar-CH
str), 2845 (CH2 str), 2500 (SH str), 3520 (NH str), 1550 (C=N
1
str), 1300 (C-N str), 698 (C-S str), 698 (C-Cl str). H NMR
Antibacterial activity of synthesis compounds on bac-
teria: Agar well-diffusion method was used to screen the
antibacterial activity of synthesized compounds (TP-1 to TP-
6) at 50 and 100 µg and the compounds showed concentration
amide N-H δ 8.18 (s, 1H) triazole 4-chloro Ar-H δ 7.48-7.86
(m, 4H), -S-H δ-4.80 (s, 1H), piperine (C=CH) δ 6.06 (d, 1H),
δ -7.28 (t, 1H), δ 6.73 (t, 1H), δ -6.75 (d, 1H)), Ar-H δ 6.75-
7.03 (m, 3H), O-CH2 δ -5.96 (s, 2H), 13C NMR (125 MHz,

1080 Kumar et al.
Asian J. Chem.
dependent activity (Table-1). Among tested drugs some are
more active inhibition and some are less inhibition against
tested bacterial strains [Bacillus subtilis (Gram-positive) and
escherichia coli (Gram-negative)]. The results of the current
study describes that tested compounds were more active against
Gram-positive bacteria compared to Gram-negative bacteria.
TP-2 showed highest antibacterial activity against Bacillus
subtilis, the diameter value of zone of inhibition was 22 mm
for 100 µg concentration and 15 mm for 50 µg concentration.
On the other hand, standard antibiotic 30 µg vancomycine
showed 32 mm zone of inhibition against the same organism.
TP-2 compounds inhibition was 31.5 % less than of the vanco-
mycine (30 µg) rate of inhibition against the Bacillus subtilis.
TP-2 inhibition was followed by the TP-6 and TP-3 com-
pounds. They showed 20 mm and 19 mm zone of inhibition,
respectively against the Bacillus subtilis. Other three compounds
TP-1, TP-4 and TP-5 also showed moderate inhibition activity
against Bacillus subtilis, i.e. 12, 11 and 15 mm, respectively.
activity showing importance of halogen and nitro groups in
the compounds.
Conclusion
A new series of piperine-triazole analogs were synthesized
with simple and efficient methods and screened for antibac-
terial activity and their results concludes that the presence of
chloro substituted derivatives possess good antimicrobial
activity against Gram-positive bacteria and 3,5-dinitrophenyl
derivatives are moderately active.
CONFLICT OF INTEREST
The authors declare that there is no conflict of interests
regarding the publication of this article.
REFERENCES
1. E.L. Souza, T.L.M. Stamford, E.O. Lima, V.N. Trajano and J.M. Barbosa
Filho, Braz. Arch. Biol. Technol., 48, 549 (2005);
https://doi.org/10.1590/S1516-89132005000500007.
2. S.A. Lee, S.S. Hong, X.H. Han, J.S. Hwang, G.J. Oh, K.S. Lee, M.K.
Lee, B.Y. Hwang and J.S. Ro, Chem. Pharm. Bull., 53, 832 (2005);
https://doi.org/10.1248/cpb.53.832.
TABLE-1
MEAN VALUE OF ZONE OF INHIBITION (mm)
FOLLOWED BY STANDARD ERROR OF ANTI-
BACTERIAL ACTIVITY OF SELECTED COMPOUNDS
3. B. Chopra,A.K. Dhingra, R.P. Kapoor and D.N. Prasad, Open J. Chem.,
3, 75 (2016);
https://doi.org/10.2174/1874842201603010075.
4. I.A. Khan, Z.M. Mirza,A. Kumar, V. Verma and G.N. Qazi, Antimicrob.
Agents Chemother., 50, 810 (2006);
https://doi.org/10.1128/AAC.50.2.810–812.2006.
5. P. Ganesh, R.S. Kumar and P. Saranraj, Cent. Eur. J. Exp. Biol., 3, 36
(2014).
6. Z.M. Mirza, A. Kumar, N.P. Kalia, A. Zargar and I.A. Khan, J. Med.
Microbiol., 60, 1472 (2011);
https://doi.org/10.1099/jmm.0.033167-0.
7. Z. Zarai, E. Boujelbene, N.B. Salem, Y. Gargouri and A. Sayari, LWT-
Food Sci. Technol., 50, 634 (2013);
Gram-negative
Gram-positive
(B. subtilis)
(E. coli)
Compd.
100 µg
50 µg
100 µg
50 µg
12 0.21
12 0.31
10 0.40
10 0.33
15 0.45
16 0.33
10 0.33
10 0.41
12 0.19
22 0.15
19 0.45
11 0.45
14 0.32
20 0.52
10 0.36
15 0.45
13 0.19
TP-1
TP-2
TP-3
TP-4
TP-5
8
8
0.43
0.15
8
9
0.09
0.29
10 0.39
12 0.35
12 0.17
TP-6
Vancomycine
(30 µg)
30 1.95
32 1.43
https://doi.org/10.1016/j.lwt.2012.07.036.
8. T. Toyoda, L. Shi, S. Takasu, Y.M. Cho, Y. Kiriyama, A. Nishikawa, K.
Ogawa, M. Tatematsu and T. Tsukamoto, Helicobacter, 21, 131 (2016);
https://doi.org/10.1111/hel.12243.
All six compounds showed inhibition activity against Gram-
negative (Escherichia coli) bacteria.Among them, TP-6 showed
highest antibacterial activity against Escherichia coli, the dia-
meter value of zone of inhibition was 16 mm at 100 µg concen-
tration and 12 mm at 50 µg concentration. On the other hand,
standard antibiotic 30 µg vancomycine showed 30 mm zone
of inhibition against the same organism. TP-6 compounds
inhibition was 46.7 % less than of the 30 µg vancomycine rate
of inhibition against the Escherichia coli. TP-6 rate of inhi-
bition was followed by the TP-5, TP-2 and TP-1 compounds
inhibition activity, they showed 15 mm, 12 mm and 12mm
zone of inhibition, respectively against the Escherichia coli.
Other compounds TP-3 and TP-4 also showed moderate
inhibition activity against Escherichia coli, i.e. 10 mm each.
The results of the current study confirms that compounds
TP-2 and TP-6 more active against the tested bacterial strains
and was equivalent to standard drug. The structural similarity
between them concludes that the existence of Nitro groups at
3rd and 5th position to benzene ring for TP-2 and halogen group
at 4th position to benzene ring exhibited excellent antibacterial
9. W.L. Dong, Z.X. Liu, X.H. Liu, Z.M. Li, W.G. Zhao, Eur. J. Med. Chem.,
45, 1919 (2010);
https://doi.org/10.1016/j.ejmech.2010.01.032.
10. A.R. Bhat, A. Azam, I. Choi and F. Athar, Eur. J. Med. Chem., 46, 3158
(2011);
https://doi.org/10.1016/j.ejmech.2011.04.013.
11. P. Umadevi, K. Deepti and D.V.R. Venugopal, Med. Chem. Res., 22,
5466 (2013);
https://doi.org/10.1007/s00044-013-0541-4.
12. T.K.Z. Aldaly, J. Basrah Res., 36, 5 (2010).
13. A. Kumar, I.A. Khan, S. Koul, J.L. Koul, S.C. Taneja, I. Ali, F. Ali, S.
Sharma, Z.M. Mirza, M. Kumar, P.L. Sangwan, P. Gupta, N. Thota and
G.N. Qazi, J. Antimicrob. Chemother., 61, 1270 (2008);
https://doi.org/10.1093/jac/dkn088.
14. R.M. Atlas, Handbook of Microbiological Media, CRC Press: London,
pp. 1226 (2004).
15. B. Bonev, J. Antimicrob. Chemother., 61, 1295 (2008);
https://doi.org/10.1093/jac/dkn090.
16. T. Johnson and C.L. Case, Laboratory Experiment in Microbiology,
edn 5 (1998).
17. J.G. Cappucino and N. Sherman, Microbiology-A Laboratory Manual,
edn 4, part 4. pp. 199 (2004).