Clubbed [1,2,3] triazoles by fluorine benzimidazole: A novel approach to H37Rv inhibitors as a potential treatment for tuberculosis

Article abstract of DOI:10.1016/j.bmcl.2008.09.096

A Novel Clubbed [1,2,3] triazoles with fluorine benzimidazole series of H37Rv strain inhibitors, potentially useful for the treatment of tuberculosis is disclosed on the basis of promising results of preliminary antimicrobial study. Evaluation of the SAR

Full text of DOI:10.1016/j.bmcl.2008.09.096

Bioorganic & Medicinal Chemistry Letters 18 (2008) 6244–6247
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Clubbed [1,2,3] triazoles by fluorine benzimidazole: A novel approach
to H37Rv inhibitors as a potential treatment for tuberculosis
Charansingh Gill a, , Ganesh Jadhav a,b, Mohammad Shaikh a,b, Rajesh Kale a,b, Anant Ghawalkar a,
*
Deepak Nagargoje a, Mahendra Shiradkar c
a Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, Maharashtra 431004, India
b Division of Medicinal Chemistry, Wockhardt Research Centre, D-4, Chikalthana M.I.D.C. Area, Aurangabad, Maharashtra 431210, India
c Chemical Biology Programm, Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR 97239, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 14 July 2008
Revised 23 September 2008
Accepted 27 September 2008
Available online 2 October 2008
A Novel Clubbed [1,2,3] triazoles with fluorine benzimidazole series of H37Rv strain inhibitors, poten-
tially useful for the treatment of tuberculosis is disclosed on the basis of promising results of preliminary
antimicrobial study. Evaluation of the SAR of substitution within these series has followed the identifica-
tion of a range of compounds. Some of the derivatives are under further evaluation showing better con-
siderable activity compared to rifampin.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords:
Antitubercular activity
H37Rv strain
Antimicrobial activity
Benzimidazole
[1,2,3] Triazole
Tuberculosis is primary cause of comparatively high mortality
worldwide, despite the availability of highly active antitubercular
drugs. The statistics shows that around three million people
throughout the world die annually from tuberculosis1,2 and today
more people dies from tuberculosis than ever before.3 Therefore,
the development of new drugs with activity against multi drug-
resistant (MDR) TB, extensively drug-resistant (XDR) TB, and latent
TB is a priority task, which will shorten the current chemotherapy.
As per the literature, after nitrogen, fluorine occupies the position
of second favorite hetero-element in life science-oriented research.
Over 10% of newly registered pharmaceutical drugs and some 40%
of newly registered agrochemicals contain one or more fluorine
atoms.4 Fluorine containing benzimidazoles, which are showing
biological activity, are well documented in the literature.5 Along
with this, the azoles antitubercular may be regarded as a new class
providing truly effective drugs, which are reported to inhibit bacte-
ria by blocking the biosynthesis of certain bacterial lipids and/or by
additional mechanisms.6,7 Triazole, in particular, [1,2,3] triazole are
among the various heterocycles that have broad pharmaceutical
and medicinal applications like anti-HIV activity,8 antimicrobial
activity against gram positive bacteria, 9 inhibition of histidine bio-
inflammatory agents.13 In addition to this, [1,2,3]-triazoles have
found broad applications in agrochemicals as fungicides and plant
growth regulator as well as industrial applications in dyes, corro-
sion inhibition (of copper and copper alloys) and photostabiliz-
ers.14 In continuation, benzimidazole nucleus is an important
pharmacophore in drug discovery having therapeutic applica-
tions.15 So after extensive literature search, it was observed that,
till date enough efforts have not been made to combine these
two moieties as a single molecular scaffold and to study its antimi-
crobial activity followed by antitubercular activity against H37Rv
strain. Along with this, literature reveals that, use of an electron
withdrawing groups attached a benzimidazole ring, a heterocycle
that, along with structure related benzthiazole is often found in
molecules with antimycobacterial activity. In continuation of our
research work to establish probable pharmacological activities of
[1,2,3] triazole and fluorine benzimidazole, we herein report the
synthesis of 2-(3-fluoro-phenyl)-1-[1-(substituted-phenyl)-1-H-
[1,2,3]-triazol-4-yl-methyl)-1H-benzo[d] imidazole 9a–9k and its
precursor and their inhibition of proliferation of H37Rv strain of
M. Tuberculosis. In recent years, environmentally benign synthetic
methods have received considerable attention. A fast, good yield-
ing eco-friendly and catalyst-free chemical transformation by air
oxidation 8, followed by alkylation reaction for the synthesis of ti-
tle compounds 9a–9k, is designed.
10
11
synthesis,
ß-selective adrenergic receptor activity agonist,
12
bacterial and medicinal fungicides of second generation,
anti-
Synthesis of 4-bromomethyl-1-(substituted-phenyl)-1H-[1,2,
3]-triazole 5 is outlined in Scheme 1. To a solution of 2,3,4-triflu-
* Corresponding author.
E-mail address: chgill50@yahoo.com (C. Gill).
0960-894X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2008.09.096

C. Gill et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6244–6247
6245
R1
R1
R1
methyl)-1-(2,3,4-trifluorophenyl)-1H-[1,2,3]-triazole (1.5 g) 5a
was obtained as buff colored solid.
Similarly, series of 4-(bromomethyl)-1-substituted-phenyl-1H-
[1,2,3]-triazole 5a–5k was synthesized by using the respective
amine of 1a–1k. All the compounds were characterized by 1H
NMR and MS.
N
N
R2
R3
R2
R3
R2
N3
NH2
N
b
a
OH
R3
1
2
3
c
R1
R1
N
N
N
N
We have synthesized the target molecule, 2-(3-fluoro-phenyl)-
1-[1-(substituted-phenyl)-1-H-[1,2,3]-triazol-4-yl-methyl)-1H-
benzo[d] imidazole 9a–9k. Condensation of o-phenylenediamine 6
with 3-fluoro benzaldehyde 7 in toluene or xylene at 110 °C for 1 h
by air oxidation without using oxidizing agents or catalysts, fur-
nished the 2-(3-fluoro-phenyl)-1H benz [d] imidazole 8. The syn-
thesized intermediate was characterized by 1H NMR and MS.
Yield-73%; MS: m/z 213.2 (M+); 1H NMR (CDCl3, 400 MHz), d
(ppm): 7.4 (m, 2H, ArH), 7.21 (m, 2H, ArH), 7.12–7.16 (m, 2H,
ArH), 5.65 (s, 1H, –CH2).
Then the subsequent reaction of 3-fluoro benzimidazole 8 with
substituted 4-(bromomethyl)-1-phenyl-1H-[1,2,3]-triazole 5a–5k
using NaH as a base proceeded at room temperature to furnish
2-(3-fluoro-phenyl)-1-[1-(substituted-phenyl)-1H-[1,2,3]-triazol-
4-yl methyl)-1H-benzo[d]imidazole derivatives 9a–9k. All the
compounds were characterized by 1H NMR, FTIR, MS and elemen-
tal analysis.17–20
The in vitro antimicrobial activity of 9a–9k were assessed
against two representatives of Gram-positive and Gram-negative
bacteria viz. Staphylococcus aureus, Pseudomonas aeruginosa, Esch-
erichia coli and Salmonella typhosa. From the antibacterial screen-
ing it was observed that all compounds exhibited activity against
different organisms employed. Looking at the structure activity
relationship, marked inhibition in bacteria was observed in the
compounds 9a, 9b, 9c, 9g and 9h, whereas 9d, 9e, 9f, 9i, 9j, and
9k have shown moderate to least activity. Our results revealed
that, maximum compounds, which are showing better antimicro-
bial activities with reference to Gentamycin, had ‘Fluorine’. This
indicates that ‘Fluorine’ may be playing an important role in the
activity of the compounds. The encouraging results (Table 1) from
the antibacterial activity prompted us to opt for preliminary
screening of the titled compounds for their antitubercular activity.
The results of the in vitro evaluation of antimycobacterial activity
are reported in Tables 2 and 3.
R2
R2
N
O
S
O
d
N
O
Br
R3
R3
5a-5k
4
Scheme 1. (a) NaNO2, HCl, H2O, NaN3; (b) propargyl alcohol, CuI, Acetonitrile; (c)
Mesyl chloride, Triethylamine, dichloromethane; (d) LiBr, Acetone.
orobenzenamine 1a (2.0 g, 13.6 mmol) dissolved in 50 mL HCl:
H2O (1:1) was cooled at À5 °C by ice-salt mixture. Then a solution
of sodium nitrite (1.87 g, 27.2 mmol) dissolved in water (15 mL)
was added slowly at À5 °C. After completion of addition, the reac-
tion mixture was stirred at À5 °C for 60 min. Then the reaction
mixture was neutralized with sodium acetate (22.3 g, 272 mmol).
Following this, a solution of NaN3 (1.77 g, 27.2 mmol) in water
(15 mL) was added slowly over the period of 30 min by maintain-
ing the temp at À5 to 0 °C. After stirring for 30 min, the solution
was allowed to warm at room temperature. Extracted with ethyl
acetate (100 mL Â 2), dried the organic layer over sodium sulphate
and evaporated to yield 1-azido 2,3,4-trifluoro benzene 2a as an
oily product (1.8 g) (Scheme 2).
In the second stage, 1-azido 2,3,4-trifluoro benzene 2a (1.8 g,
10.4 mmol) was dissolved in acetonitrile (25 mL). Propargyl alco-
hol (1.16 g, 20.8 mmol) and copper iodide (0.39 g, 5.2 mmol) were
added to the above reaction mixture 16. The reaction mixture was
stirred at room temperature for 8–10 h, a solid material separated
out, was filtered, suck dried. [1-(2,3,4-trifluorophenyl)-1H-1,2,3-
triazol-4-yl] methanol 3a (1.89 g) was obtained as off white solid.
In the penultimate stage, to a solution of [1-(2,3,4-trifluorophe-
nyl)-1H-1,2,3-triazol-4-yl]-methanol (1.85 g, 8.07 mmol) dissolved
in dichloromethane (20 mL) was added triethyl amine (1.22 g,
12.1 mmol) and mesyl chloride (1.1 g, 9.7 mmol) at room temper-
ature. The reaction mixture stirred for 30 min and completion of
reaction was monitored by TLC. Concentrate under vacuum and
charged water, a solid material separates out, was filtered, suck
At the commencement of this program, compound 9a was the
only target, which had ‘F’. As our program progressed, it have been
observed that this target with fluoro substitution possess enhanced
anti-mycobacterial activity, >96% of inhibition at 6.25 mg concen-
tration while other compounds 9d, 9e, 9h, 9j and 9k exhibited less
than 90% inhibition at the same concentration.
Thus, we have considered 9a as a lead molecule and subsequent
structural modifications were carried out using several alternatives
for fluoro substitution. As a first step towards lead optimization,
we have incorporated ‘F’ at 2, 3 & 4 in different variations, wherein
dried.
[1-(2,3,4-trifluorophenyl)-4-{methylsulphonyl}-methyl]-
1H-1,2,3-triazole 4a (1.9 g) was obtained as off white solid.
In the final stage, to a solution of [1-(2,3,4-trifluorophenyl)-4-
{methylsulphonyl}-methyl]-1H-1,2,3-triazole (1.9 g, 6.19 mmol)
in acetone, charged lithium bromide (1.07 g, 12.37 mmol) and then
refluxed for 1–2 h. After completion of reaction (monitored on
TLC), distilled out acetone completely invacuo. Charged water, a
solid material separates out, was filtered, suck dried. 4-(bromo-
O
F
F
NH2
NH2
a
N
H
+
N
H
7
8
6
F
N
N
N
N
F
N
N
b
Br
+
N
H
R1
R3
R3
N
N
N
R2
5a-5k
R1
9a-9k
R2
8
Scheme 2. (a) Toluene, 110 °C, 30–60 min.; (b) NaH, 4-bromomethyl-1-phenyl-1H-[1,2,3]-triazole, DMF, rt.

6246
C. Gill et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6244–6247
Table 1
All the compounds, 9b, 9c, 9e, 9f and 9g that were active in the
first level screening were then tested to determine the actual min-
imum inhibitory concentration (MIC), wherein, compounds 9b, 9c
and 9g have been proven to be the most active, with MIC values
ranging from 0.32 to 0.58.
Antibacterial activity21 of the compounds 9a–9k (The value indicates bacterial growth
inhibition measured in mm).
Compound
Organisms
Sa
Pa
Ec
St
In conclusion, the antimycobacterial screening of the novel ser-
ies has demonstrated emergence of potent derivatives that has
highly electronegative part, that is, ‘Fluorine’ and may be due to
the presence of [1,2,3]-triazole ring attached to the benzimidazole.
Specifically compounds 9b, 9c and 9g, due to the better activity
against the mycobacteria, are the best choice for the preparations
of new derivatives in order to improve its effectiveness on intracel-
lular mycobacteria (macrophage) or in infected animal. Also, we
have developed an efficient methodology for the synthesis of a 2-
(3-fluoro-phenyl)-1-[1-(substituted-phenyl)-1H-[1,2,3]-triazol-4-
yl-methyl)-1H-benzo[d] imidazole derivatives and towards the
development of new pharmacophore. Finally it can be concluded
that an ideal antimycobacterial agent with minimal toxicity and
potential activity can be designed using above said compounds
as lead molecules.
9a
9b
9c
9d
9e
9f
Gent
9g
9h
9i
9j
9k
Gent
31
32
26
21
20
18
34
33
26
18
16
18
34
33
31
19
24
26
13
35
34
28
13
19
20
35
29
30
20
19
18
21
31
32
17
21
14
19
31
30
29
19
23
21
18
30
31
18
18
17
17
30
Sa: Staphylococcus aureus, Ec: Escherichia coli, Pa: Pseudomonas aeruginosa, St: Sal-
monella typhosa, Gent: Gentamycin.
Table 2
First antituberculosis screening of compounds 9a–9k.
Acknowledgments
Compound
R1
R2
R3
MICa
GI (%)b
The authors are thankful to The Head, Department of Chemistry,
Dr. Babasaheb Ambedkar Marathwada University, Aurangabad-
431004 (MS), India for providing laboratory facility and Wockhardt
Research Centre, Aurangabad, Maharashtra, India for their valuable
support.
9a
9b
9c
9d
9e
9f
9g
9h
9i
F
H
H
OMe
H
F
F
H
H
F
F
F
F
F
H
H
Ome
Me
F
H
CF3
H
<6.25
<6.25
<6.25
<6.25
<6.25
<6.25
<6.25
<6.25
<6.25
<12.5
<12.5
—
96
96
—
96
96
96
—
—
—
—
H
H
H
H
H
H
H
H
References and notes
9j
9k
Me
H
1. Snider, D. E.; Raviglione, M.; Kochi, A. In Tuberculosis: pathogenesis; Bloom, B.,
Ed., 1st ed.; Protection and Control: Global Burden of Tuberculosis; ASM Press:
Washington, DC,, 1994; p 3.
2. Ballell, L.; Field, R. A.; Duncan, K.; Young, R. J. Antimicrob. Agents Chemotheraphy
2005, 49, 2153.
3. (a) Neu, H. C. Science 1992, 257, 1064; (b) Spigelman, M. K. New tuberculosis
therapeutics: a growing pipeline. J. Infect. Dis 2007, 196, S28; (c) Cegielski, J. P.;
Chin, D. P.; Espinal, M. A.; Frieden, T. R.; Rodriquez Cruz, R.; Talbot, E. A.; Weil,
D. E.; Zaleskis, R.; Raviglione, M. C. Prospects for the 21st century. Infect. Dis. Clin.
North Am 2002, 161, 1.
Me
a
MIC in (l
g/mLÀ1). MIC of rifampin: 0.015–0.125 mg mLÀ1 versus M. tubercu-
losis H37Rv (97% inhibition).
b
Growth inhibition of virulent H37Rv strain of M. tuberculosis.
Table 3
Second level antituberculosis screening
4. Cottet, Fabrice.; Marull, Marc.; Lefebvre, Olivier.; Schlosser, Manfred. Eur. J. Org.
Chem. 2003, 1559 (and reference cited within [1–9]).
SN
MIC (l
M)a
5. a O’Neil, M. J.; Smith, M.; Heckman, P.E. (Eds), Merck and Co. Inc, Monograph
Number 861.13th Edition, CAS No. 68844-77-9.; b Monograph Number 5378.
CAS No. 103577-45-3.; c Monograph Number 4144. CAS No. 31430-15-6.; d
Monograph Number 3484. CAS No. 548-73-2.
6. Babaoghe, K.; Page, M. A.; Johns, V. C.; Naismith, J. H.; Lee, R. E. Novel Biorg. Med.
Chem. Lett. 2003, 13, 3227.
9b
9c
9e
9f
0.34
0.58
6.25
3.13
0.32
9g
7. Shiradkar, M. R.; Bhandari, S. V.; Kale, R. P.; Laghate, A.; Rathi, A. Asian J. Chem.
2006, 18, 2700.
a
Actual minimum inhibitory concentration (MABA assay).
8. (a) Tornoe, C. W.; Christensen, C.; Meldal, M. J. Org. Chem. 2002, 67, 3057; (b)
Alvarez, R.; Velarquez, S.; San, F.; Aquaro, S.; De, C.; Perno, C. F.; Karlsson, A.;
Balzarini, J.; Camarasa, M. J. J. Med. Chem. 1994, 37, 4185; (c) Velarquez, S.;
Alvarez, R.; Perez, C.; Gago, F.; De, C.; Balzarini, J.; Camarasa, M. J. Antivir. Chem.
Chemother. 1998, 9, 481.
9. Genin, M. J.; Allwine, D. A.; Anderson, D. J.; Barbachyn, M. R.; Emmert, D. E.;
Garmon, S. A.; Graber, D. R.; Grega, K. C.; Hester, J. B.; Hutchinson, D. K.; Morris,
J.; Reischer, R. J.; Ford, C. W.; Zurenko, G. E.; Hamel, J. C.; Schaadt, R. D.; Stapert,
D. B.; Yagi, H. J. Med. Chem. 2000, 43, 953.
10. Ventura, I.; Perezgonzales, J.; Ramon, D. Microbiol. Lett. 1997, 149, 207.
11. Brockunier, L. L.; Parmee, W. P.; Forrest, M. J.; Hom, G. J.; Maclutyre, D. E.; Ok,
H. O.; Colwell, L. F.; Dena, L.; Feeney, W. P.; Candelore, M. R.; Cascuri, M. A.;
Tota, L.; Wyvratt, M. J.; Fisher, M. H.; Weber, A. E. Bioorg. Med. Chem. Lett. 2000,
10, 2111.
all the alterations made 9b, 9c, 9f and 9g, shown promising activ-
ity, that is, >96% of inhibition at 6.25 mg concentration, proving
that the modifications are towards synthesis of a pharmacophore.
The next structural modification done was a trifluoromethyl sub-
stitution product, 9i but this change resulted in a substantial loss
of biological activity. This loss may indicate retardation in the
intracellular transport due to highly electronegativity in one re-
gion. In case of electron donating groups, like methyl substitutions
resulted in loss of activity. The biological data generated reveals
that compounds having an electron-withdrawing group attached
may prove a template for anti tuberculosis activity for further
development. It was also observed that the promising antimicrobi-
als have proved to be better antimycobacterials. Results obtained
clearly related to the electron withdrawing ability of the substitu-
ents on the benzyl nucleus with heterocyclic ring. Even though
cytotoxicity has not been evaluated for this series of molecules.
So compound could form a promising core for lead optimization.
[12]. Patai, S. The Chemistry of the Azide gr; Inter-Science publisher: New York, N Y.,
1971. 331-388.
13. Michaelidou, A. S.; Hadjipavloulitina, D. Chem. Rev. 2005, 105, 3253.
14. (a) Review on [1,2,3] triazoles, Dehne, H. in Methoden der Organischem chemie
(houben- Weyl) (E.Schumann, Ed.), Thieme: Stuttgart, vol E8d 1994, 305–405.;
(b) Wamhoff, H. in Katritzky, A.R.; Rees, C.W (Eds.), Comprehensive Heterocyclic
Chemistry. Pergamon: Oxford, 1984, vol. 5, pp. 669–732.; (c) Fan, W. Q.;
Katritzky, A. R. In Comprehensive Heterocyclic Chemistry II: Katritzky, A. R.; Rees,
C. W.; Scriven, E. F. Eds. Elsevier Science: Oxford, 1996, vol. 4, 1–126.
15. Thimmegoda, N. R.; Nanjunda Swamy, S.; Ananda Kumar, C. S.; Yip, G. W.;
Rangppa, K. S. Biorg. Med. Chem. Lett. 2008, 18, 432.

C. Gill et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6244–6247
6247
16. (a) Jin, T.; Kamijo, S.; Yamamoto, Y. Eur. J. Med. Chem. 2004, 3789; (b) Tornoe, C.
W.; Christensen, C.; Meldal, M. J. Org. Chem. 2002, 67, 3057; c Patent No. WO
2004/048350. A methodology of triazole ring formation.
21. Antimicrobial activity: The title compounds were screened for the antimicrobial
activity against different microorganisms under the following conditions.
(Table 3) Method: Well diffusion method22
,
Medium: The nutrient agar
17. Experimental: The melting points were estimated by Veggo programmable
(microprocessor based) melting point apparatus and are uncorrected. 1H NMR
spectra were recorded on a Varian 400 MHz spectrometer MHz instrument
using CDCl3 as solvent using TMS as internal standard; the chemical shifts (d)
are reported in ppm Signal multiplicities are represented by s (singlet), d
(doublet), t (triplet), ds (double singlet), dd (double doublet), m (multiplet) and
br s (broad singlet). IR spectra were recorded on (KBr disc) using a FTIR bruker
Vector 22 Spectrophotometer. Elemental analyses were determined on
Elementor Vario instrument. EI-MS spectra recorded on micromass-quatro –
II. The purity of the compounds was checked on Merck precoated silica gel 60
F-254. All the reagents, solvents used were of commercial grade only.
18. General experimental procedure for the synthesis of 2-(3-fluoro-phenyl)-1-[1-
(substituted-phenyl)-1H-[1,2,3]-triazol-4-yl-methyl)-1H-benzo[d] imidazole
medium, solvent: chloroform: concentrations: 50 and 100 M. Condition: 24 h
l
at 24–28 °C, Standard: The antibiotic Gentamycin The nutrient agar medium,
20 mL was poured into the sterile petri dishes. To the solidified plates, wells
were made using a sterile cork borer 10 mm in diameter. The 24 h sub-cultured
bacteria was inoculated in the petri-plates, with a sterile cotton swab dipped in
the nutrient broth medium. After inoculating, the compounds were dissolved
separately with the chloroform solvent and poured into the wells with varying
concentrations ranging from 50 and 100 lM using a micropipette. The plates
were left over for 24 h at 24–28 °C. The antibiotic Gentamycin was used as a
standard for comparative study. The percentage of inhibition was calculated by
the formula % Inhibition = Diameter of the inhibition zone  100.
22. Antitubercular activity: Primary screening was conducted at 6.25 l
g mLÀ1
against M. tuberculosis H37Rv (ATCC 27294) in BACTEC 12B medium using a
23
9a–9k. To
a
suspension of sodium hydride (0.94 mmol) in dimethyl
broth microdilution assay, the Microplate Alamar Blue Assay (MABA).
formamide was added 2-(3-fluorophenyl)-1H-benz[d] imidazole (8)
(0.47 mmol) at room temperature and stirred the reaction mixture for
30 min. To this reaction mixture, substituted 4-bromomethyl-1H-[1,2,3]-
triazole (5a–i) (0.52 mmol) was then added at room temperature and stirred
for 30 min. After completion, the reaction mixture was quenched with ice
water. The solid that separates was filtered and dried at room temperature 9a–
9k.
Compounds exhibiting fluorescence were tested in the BACTEC 460
24,25
radiometric system.
Compounds showing more than/95% inhibition in
the primary screening were considered active and then re-tested at a lower
concentrations against M. tuberculosis H37Rv in order to determine the actual
MIC, using MABA. The MIC is defined as the lowest concentration effecting a
reduction in fluorescence of 95% with respect to the controls. Rifampin (RMP)
was used as the reference compound (RMP MIC=/0.015–0.125 mg mLÀ1). We
also have done cytotoxicity analysis of the above-synthesized compounds,
using neutral red uptake by using Vero-C-1008 cell line at various
concentrations (6.25–50 lg/mL), none of them were found toxic. Hence the
activities of the above-synthesized compounds were not due to cytotoxicity of
compounds.
19. Synthesis
of
2-(3-fluoro-phenyl)-1[1-(2,3,4-trifluoro-phenyl)-1H-[1,2,3]-
triazol-4-yl-methyl]-1H-benz [d] imidazole (9a). The compound was
obtained using 4-bromomethyl-1-(2,3,4-trifluorol-phenyl)-4H-[1,2,3]-triazole
(5a) as a buff colour crystalline solid (9a). Yield 74%; mp: 178-180 °C; IR (KBr):
3064, 1591, 1521, 1046, 748 cmÀ1.; 1H NMR (CDCl3, 400 MHz), d (ppm): 7.86 (s,
1H, CH-triazole ring), 7.82 (d, 1H, ArH), 7.67 (m, 3H, ArH), 7.51 (m, 2H, ArH),
7.30 (dd, 2H, ArH), 7.26 (m, 1H, ArH), 7.15 (dd, 1H ArH,), 5.65 (s, 2H, CH2); MS:
m/z 424.2 (M+); Anal. calcd for C22H13F4N5: C, 62.41; H, 3.10; N, 16.54; found C,
62.43; H, 3.18; N, 16.66.
23. M. A. Pfaller, A. Espinel-Ingroff, R. N. Jones .NCCLS, 2002, Reference method for
broth dilution antifungal susceptibility testing of yeasts; Approved Standard,
NCCLS document, 2nd ed.; [ISBN 1-56238-469-4], P. M27–A2.
24. Collins, L.; Franzblau, S. G. Antimicrob. Agents Chemother. 1997, 415, 1004.
25. Franzblau, S. G.; Cook, M. B.; Quenzer, V. K.; Ferguson, R. M.; Gilman, R. H. J.
Clin. Microbiol. 1998, 36, 362.
20. By the procedure mentioned in the reference 19, we have synthesized all the
compounds 9a–9k and characterized by 1H NMR, FTIR, MS and elemental
analysis.