Design synthesis and biological evaluation of 3-substituted triazole derivatives

Article abstract of DOI:10.1016/j.cclet.2010.11.029

Based on the active site of lanosterol 14α-demethylase of azole antifungal agents, sixteen 1-(1H-1,2,4-triazole-1-yl)- 2-(2,4-difluorophenyl)-3- (N-n-butyl-N-1-substitutedbenzyl-4-methylene-1H-1,2,3-triazole)-2-propanols have been designed, synthesized and evaluated as antifungal agents. Results of preliminary antifungal tests against eight human pathogenic fungi in vitro showed that some of the compounds exhibited excellent activities with broad spectrum.

Full text of DOI:10.1016/j.cclet.2010.11.029

Available online at www.sciencedirect.com
Chinese Chemical Letters 22 (2011) 519–522
www.elsevier.com/locate/cclet
Design synthesis and biological evaluation of 3-substituted
triazole derivatives
Bao Gang Wang a,b,1, Shi Chong Yu a,1, Xiao Yun Chai a, Yong Zheng Yan a,
a
Hong Gang Hu a, , Qiu Ye Wu
*
a Department of Organic Chemistry, School of Pharmacy, Second Military Medical University, Shanghai 200433, China
b Pharmacy Team, Administrative Brigade of Postgraduate, Second Military Medical University, Shanghai 200433, China
Received 23 August 2010
Available online 3 March 2011
Abstract
Based on the active site of lanosterol 14a-demethylase of azole antifungal agents, sixteen 1-(1H-1,2,4-triazole-1-yl)- 2-(2,4-
difluorophenyl)-3-(N-n-butyl-N-1-substitutedbenzyl-4-methylene-1H-1,2,3-triazole)-2-propanols have been designed, synthesized
and evaluated as antifungal agents. Results of preliminary antifungal tests against eight human pathogenic fungi in vitro showed that
some of the compounds exhibited excellent activities with broad spectrum.
# 2010 Hong Gang Hu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Keywords: Synthesis; Triazole; Antifungal activity; 1,3-Dipolar cycloaddition
During the past two decades, fungal infections have caused a number of disease and mortality, particularly in
individuals with immunocompromised hosts, such as patients undergoing anticancer chemotherapy or organ
transplants and patients with AIDS [1]. Clinically, triazoles such as fluconazole, voriconazole, and itraconazole
(Fig. 1) are widely used as antifungal agents for their significant activity against most yeasts and filamentous fungi.
However, triazole drugs are often associated with hepatotoxicity and limited antifungal spectrum [2,3]. Moreover,
resistance to azoles is emerging and may pose a serious health problem in the future [4]. Therefore, the research on
low-toxicity and broad spectrum antifungal agents has a great significance.
The antifungal activity of azoles are exerted through inhibiting the lanosterol 14a-demethylase (CYP51) [5]. A
three-dimensional model of CYP51 of Candida albicans and its interaction with azole antifungals were reported by Ji
et al. [6]. In general, the active site of CYP51 for ligand binding can be divided into four subsites: a coordination bond
with iron of the heme group, the hydrophilic H-bonding region, the hydrophobic region, and the narrow hydrophobic
cleft formed by the residues in the helix B0-meander 1 loop and N-terminus of helix I [7]. According to the active site of
CYP51, the classical structure of the triazoles, propanols-triazole-2,4-difluorophenyl, was reserved. The hydroxy of
propanols could form H-bonding with the H-bonding region, the N4 atom of triazole could be coordinated to iron atom
of the heme and the 2,4-difluorophenyl group could be located in to the hydrophobic pocket. In addition, a series of
* Corresponding author.
E-mail addresses: wuqy6439@sohu.com (H.G. Hu), huhonggang_fox@msn.com (Q.Y. Wu).
1
Bao Gang Wang and Shi Chong Yu contributed equally to this work.
1001-8417/$ – see front matter # 2010 Hong Gang Hu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
doi:10.1016/j.cclet.2010.11.029

5[()TD$FIG] 20
B.G. Wang et al. / Chinese Chemical Letters 22 (2011) 519–522
Fig. 1. The structure of fluconazole, voriconazole and itraconazole.
triazoles containing the 1,2,3-triazole side chain, considering the special property of it, was designed and synthesized
in order to improve the activity of the title compounds.
The synthetic route of title compounds was outlined in the Scheme 1. The intermediate oxirane 4 was synthesized
with known procedures [8]. 1-(1H-1,2,4-triazole-1-yl)-2-(2,4-difluorophenyl)-3-[N-n-butylamino]-2-propanol 5 was
obtained by the reaction of compound 4 and n-butylamine in EtOH in the presence of Et3N. Compound 6 was obtained
by the reaction of 5 and propargyl bromide in CH3CN in the presence of K2CO3. The sodium azide and substituted
benzyl bromide were mixed and stirred in DMSO for 12 h and 6 was allowed to add into the mixture without
purification and react via CuSO4ꢀ5H2O and sodium ascorbate catalyzing. By the intermolecular 1,3-dipolar
cycloaddition, the title compounds 7a–p were obtained.
In vitro antifungal activity was measured by means of the minimal inhibitory concentrations (MIC) using the serial
dilution method in 96-well microtest plates. Test fungal strains were obtained from the ATCC or clinical isolates. The
[()TD$FIG]
Scheme 1. Conditions: (a) ClCH2COCl, AlCl3, 50 8C, 5 h, in 80.0% yield; (b) C6H5CH3, NaHCO3, 1H-1,2,4-triazole, reflux, 5 h, in 41.7% yield; (c)
C6H5CH3, (CH3)3SOI, NaOH, cetyltrimethylammonium bromide, 60 8C, 3 h; (d) CH3SO3H, 0 8C, 1 h, in 52.6% yield; (e) CH3CH2OH, Et3N, n-
butylamine, reflux, 6 h, in 91% yield; (f) CH3CN, propargyl bromide, rt. 6 h, in 62.2% yield; (g) DMSO, NaN3, substituted benzyl bromide, rt. 5–6 h;
(h) CuSO4.5H2O, VitC-Na, in 90.0–95.0% yield, two steps.

B.G. Wang et al. / Chinese Chemical Letters 22 (2011) 519–522
521
Table 1
Structure and in vitro antifungal activity of the title compounds.
Compounds
R
MIC80 (mg/mL)
C.alb SC5314
C.neo
C.alb Y0109
C.par
C.tro
T.rub
C.kef
A.fum
7a
7b
7c
2-F
3-F
1
8
1
16
2
2
4
1
>64
>64
>64
>64
>64
>64
>64
>64
>64
>64
>64
>64
>64
>64
>64
>64
2
<0.125
<0.125
4
0.25
<0.125
0.5
1
0.0156
4-F
2
0.0625
0.25
0.25
1
0.625
7d
7e
3-Cl
<0.125
<0.125
1
16
<0.125
<0.125
0.5
0.25
0.0156
0.0039
0.0156
4-Cl
2
16
<0.125
8
<0.125
7f
7g
2-Br
4
64
>64
>64
2
0.5
4
8
3-Br
4
1
>64
8
32
>64
>64
0.25
16
0.0625
7h
7i
4-Br
4
1
8
0.5
2
4-CH3
2-NO2
3-NO2
4-NO2
2-CN
3-CN
<0.125
2
<0.125
<0.125
4
<0.125
2
7j
64
64
64
64
64
>64
>64
4
4
4
7k
7l
4
8
8
8
2
4
4
8
1
32
16
16
32
32
0.0625
2
0.0625
0.0625
4
7m
7n
7o
1
16
16
4
4
4
16
>64
32
2-Cl,4-Cl
4
8
16
16
0.0625
7p
ICZ
FCZ
2-Cl,6-Cl
16
8
64
8
–
–
<0.0625
0.5
0.125
0.625
0.5
0.0625
<0.125
<0.0625
<0.125
8
1
>64
Abbreviations: C.alb SC5314, Candida albicans SC5314; C.neo, Cryptococcus neoformans; C.alb Y0109, Candida albicans Y0109; C par,
Candida parapsilosis; C.tro, Candida tropicalis; T.rub, Trichophyton rubrum; C.kef, Candida kefyr; A.fum, Aspergillus fumigatus.ICZ, Itraconazole;
FCZ, Fluconazole.
MIC determination was performed according to the national committee for clinical laboratory standards (NCCLS)
recommendations [9]. The results of antifungal activities in vitro of the target compounds were listed in Table 1.
All the title compounds containing 1,2,3-triazole are first reported and their structures were confirmed by 1H NMR,
MS, IR and elemental analysis.
Although 1,2,3-triazole moiety does not occur in nature, it is attractive as a connecting group thanks to the stability
of metabolic degradation and capability of hydrogen bonding, which can be favorable in binding of biomolecular
targets and for solubility [10]. The group of Pore et al. had reported some 1,2,3-triazole molecules containing
molecules as azole antifungals and the molecules exhibited excellent activities against Candida species [11]. In
addition, the Cu(I) catalyzed intermolecular 1,3-dipolar cycloaddition used to introduce the side chain containing 1,4-
disubstituted-1,2,3-triazole was in excellent yield and easy to purify.
The structure and in vitro antifungal activities were listed in Table 1. All the title compounds were active against
eight pathogenic fungi to such an extent. The activities against Candida albicans SC5314 and Candida kefyr of some
of the title compounds are stronger than those of fluconazole and itraconazole. Some of the target compounds showed
good MIC values less than 0.0156 mg/mL and proved to be more potent than fluconazole and are comparable with that
of itraconazole. Compounds 7b, 7d, 7e and 7h exhibited strong antifungal activities against eight test fungi
comparable to the control drug itraconazole except Aspergillus fumigatus. The study also proved that the long side
chain containing the 1,4-disubstituded-1,2,3-triazole can improve the activities against fungi of the target compounds.
In addition, the substituent R on phenyl group has a great influence on antifungal activities. The activities of
compounds 7j–p containing the strong electron-withdrawing group such as –CN, –NO2 or two halogen were lower
than other compounds, respectively, suggesting that the 1,2,3-triazole group could form hydrogen-bonding interaction
with the enzyme and the electron-donating conjugation can firm the interaction. To clarify the binding mode of our
synthesized compounds, the mode of action of this class of compounds will be explored by molecular modeling. These
results may provide some guidance for novel azole antifungal research.
Acknowledgments
This work was supported by the National Natural Science Foundation of China (No. 20772153), Shanghai Leading
Academic Discipline Project (No. B906) and by Creativity and Innovation Training Program of Second Military
Medical University(No. MS2009042).

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