Novel imidazole derivatives as antifungal agents: Synthesis, biological evaluation, ADME prediction and molecular docking studies

Article abstract of DOI:10.1080/10426507.2019.1565761

A series of 2-(substituteddithiocarbamoyl)-N-[4-((1H-imidazol-1-yl)methyl)phenyl]acetamide derivatives was designed and synthesized to combat the increasing incidence of drug-resistant fungal infections. All synthesized compounds were characterized by IR, ¹H-NMR, ¹³C-NMR, and HRMS spectra and elemental analyses. Antifungal activity tests were performed against four different fungal strains. Molecular docking studies were performed to investigate the mode of action towards the fungal lanosterol 14α-demethylase, a cytochrome P450-dependent enzyme. ADME studies were carried out and a connection between activities and physicochemical properties of the target compounds was determined. Most of the final compounds exhibited significant activity against Candida albicans and Candida krusei with MIC₅₀ value 12.5 μg/mL. The results of in vitro anti-Candida activity, a docking study and ADME prediction revealed that the newly synthesized compounds have potential anti-Candida activity and evidenced the most active derivative, 5b (2-Pyrrolidinthiocarbonylthio-N-[4-((1H-imidazol-1-yl)methyl)phenyl]acetamide), which can be further optimized as a lead compound.

Full text of DOI:10.1080/10426507.2019.1565761

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: https://www.tandfonline.com/loi/gpss20
Novel imidazole derivatives as antifungal agents:
Synthesis, biological evaluation, ADME prediction
and molecular docking studies
Firuze Diyar Altındağ, Begüm Nurpelin Sağlık, Ulviye Acar Çevik, İlhan
Işıkdağ, Yusuf Özkay & Hülya Karaca Gençer
To cite this article: Firuze Diyar Altındağ, Begüm Nurpelin Sağlık, Ulviye Acar Çevik, İlhan Işıkdağ,
Yusuf Özkay & Hülya Karaca Gençer (2019): Novel imidazole derivatives as antifungal agents:
Synthesis, biological evaluation, ADME prediction and molecular docking studies, Phosphorus,
Sulfur, and Silicon and the Related Elements, DOI: 10.1080/10426507.2019.1565761
To link to this article: https://doi.org/10.1080/10426507.2019.1565761
View supplementary material
Published online: 25 Jan 2019.
Submit your article to this journal
Article views: 3
View Crossmark data
Full Terms & Conditions of access and use can be found at
https://www.tandfonline.com/action/journalInformation?journalCode=gpss20

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
https://doi.org/10.1080/10426507.2019.1565761
Novel imidazole derivatives as antifungal agents: Synthesis, biological
evaluation, ADME prediction and molecular docking studies
a,b
, Ulviye Acar C¸evika,b, Ilhan Is¸ıkdag , Yusuf Ozkaya,b, and
ꢀa
Firuze Diyar Altındag , Begum Nurpelin Saglık
€
ꢀ
ꢀa
_
€
c
€
Hulya Karaca Genc¸er
b
aDepartment of Pharmaceutical Chemistry, Faculty of Pharmacy, Anadolu University, Eskis¸ehir, Turkey; Doping and Narcotic Compounds
c
Analysis Laboratory, Faculty of Pharmacy, Anadolu University, Eskis¸ehir, Turkey; Department of Pharmaceutical Microbiology, Faculty of
Pharmacy, Anadolu University, Eskis¸ehir, Turkey
ABSTRACT
ARTICLE HISTORY
Received 12 July 2018
Accepted 30 December 2018
A series of 2-(substituteddithiocarbamoyl)-N-[4-((1H-imidazol-1-yl)methyl)phenyl]acetamide deriva-
tives was designed and synthesized to combat the increasing incidence of drug-resistant fungal
infections. All synthesized compounds were characterized by IR, 1H-NMR, 13C-NMR, and HRMS
spectra and elemental analyses. Antifungal activity tests were performed against four different fun-
gal strains. Molecular docking studies were performed to investigate the mode of action towards
the fungal lanosterol 14a-demethylase, a cytochrome P450-dependent enzyme. ADME studies
were carried out and a connection between activities and physicochemical properties of the target
compounds was determined. Most of the final compounds exhibited significant activity against
Candida albicans and Candida krusei with MIC50 value 12.5 lg/mL. The results of in vitro
anti-Candida activity, a docking study and ADME prediction revealed that the newly synthesized
compounds have potential anti-Candida activity and evidenced the most active derivative, 5b (2-
Pyrrolidinthiocarbonylthio-N-[4-((1H-imidazol-1-yl)methyl)phenyl]acetamide), which can be further
optimized as a lead compound.
KEYWORDS
Imidazole; dithiocarbamate;
antifungal activity;
molecular docking
GRAPHICAL ABSTRACT
Introduction
transplants, the administration of medicine or nutrition by
venous catheters, and the rise in drug addiction, neoplasms
and diseases that suppress the immune system.[1–3]
Currently, the available antifungal agents to treat Candida infec-
tions can be divided into four categories based on their mode of
action, including azoles, polyenes, echinocandins and antimetabo-
The incidence of infection by opportunistic and pathogenic
fungi has been increasing in recent years. The occurrence of
these infections have increased since the early 1980s and have
resulted from many factors, such as the indiscriminate use of
antibiotics, the extensive practice of bone marrow and organ
€
CONTACT Yusuf Ozkay
yozkay@anadolu.edu.tr
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Anadolu University, Eskis¸ehir 26470, Turkey.
Supplemental data for this article is available online at https://doi.org/10.1080/10426507.2019.1565761.
ß 2019 Taylor & Francis Group, LLC

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
ꢀ
2
F. D. ALTINDAG ET AL.
NO2
NH2
NO2
H
N
SnCl2.2H2O
EtOH
K
2CO3/DMF
MW
N
N
N
Br
N
N
2
1
O
N
S
HN
NHCOCH2Cl
S
ClCOCH2Cl
TEA/THF
S
Acetone
N
SNa
N
N
4a-4i
N
N
3
5a-5i
5a
5b
5c
5d
5e
:
H
N
N(C2
)
5 2
N
N
S
N
N
CH3
5f
5g
5h
5i
H
N
N
N
3C
H
N
N
C2
5
N
N
N
N
Scheme 1. Synthetic procedure for target compounds.
lites.[4] Among them azole antifungal inhibitors are the most widely study of the compound 5b was conducted in an attempt to
used inhibitors in first-line antifungal therapies.[5,6]
understand their mechanism of action on the target enzyme.
Ergosterol is an essential component of the fungal cell wall,
which plays an important role in membrane fluidity, enzyme
activity, cell morphology, membrane permeability and cell cycle
progression.[6] Lanosterol-14a-demethylase (14-DM, CYP51), a
monooxygenase in fungal cells, is a key enzyme of sterol biosyn-
thesis in fungi. Azole antifungal agents inhibit 14-DM by a mech-
anism in which the heterocyclic nitrogen atom (N-3 of
imidazole) bind as the sixth ligand to the heme iron in the active
site of the enzyme, thereby altering the structure of the active site
and acting as noncompetitive inhibitors.[7,8] The efficacy of azoles
depends on the affinity of the N-1 substituent for the cytochrome
protein as well as the strength of the binding to heme iron.
Because of the presence of CYP51 in fungi and mammals and
their effects on CYP3A4, selective inhibition of CYP51 results in
depletion of ergosterol and deposition of 14-a-methylated sterols.
Thus, the growth of fungal cells is prevented.[9]
Clinically, representative antifungal drugs have certain
limitation such as, narrow spectrum of activity, non-optimal
pharmacokinetics and the emergence of drug resistance
(generally azoles). Therefore, there is an urgent need for
development of antifungal agents.[10]
Dithiocarbamates, a common class of molecular scaffold,
have a close resemblance with biomolecules such as amino
acids, peptides, proteins, enzymes, and vitamins.[11,12] It is
reported that dithiocarbamates had antimicrobial effects.[13–20]
In an effort to develop new type of antifungal azoles, we were
interested in the incorporation of dithiocarbamate moiety
with imidazoles. Therefore, in the present studies, a series of
2-(substituteddithiocarbamoyl)-N-[4-((1H-imidazol-1-yl)me-
Results and discussion
Chemistry
The synthesis of imidazole-dithiocarbamate derivatives
(5a–5i) was followed according to pathway depicted in
Scheme 1. In the first step, microwave supported synthesis
of 1-(4-nitrobenzyl)-1H-imidazole (1) was performed in
DMF. Secondly, the reduction of compound 1 by Zn/HCl in
EtOH gave the 1-(4-aminobenzyl)-1H-imidazole (2). In the
third step, 2-chloro-N-[4-((1H-imidazol-1-yl)methyl)phenyl)
acetamide (3) was obtained by the reaction of compound 2
with chloroacetyl chloride in the presence of triethyl-
amine.[21] Finally, compound 3 was reacted with the appro-
priate sodium dithiocarbamate derivatives (4a–4i) in acetone
to gain target compounds.[22] The chemical structures of the
compounds (5a–5i) were confirmed by IR, H-NMR, 13C-
1
NMR and HRMS spectral data and elemental analyses.
In the IR spectra of the compounds, stretching absorp-
tion at 3154–3262 cmꢀ1 proved N–H bond of the amide
(–NHCO–) group. Additionally, stretching absorption
belonging to carbonyl (C ¼ O) was seen at 1670–1703 cmꢀ1
.
The stretching absorption at about 1414–1611 cmꢀ1 and
813–843 cmꢀ1 was recorded for C ¼ C, C ¼ N double bonds
and 1,4-disubstituted benzene, respectively.
1
In the H-NMR spectra, methylene protons between car-
bonyl and dithioate group were recorded as a singlet peak at
4.21–4.28 ppm. N–H proton of amide group gave singlet at
thyl)phenyl]acetamide were designed, synthesized and eval- 10.29–10.35 ppm. Aromatic proton (C2–H) of imidazole
uated for their antifungal activities. In addition, a docking ring gave a peak at 7.72 ppm as a singlet. The other

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
3
Figure 1. Relative ergosterol level (REL) of C. albicans (ATCC 24433) after treatment with compound 5b, fluconazole and ketoconazole.
aromatic protons (C4–H and C5–H) of imidazole were and hence inhibition of ergosterol biosynthesis causes the end
observed at 7.72 and 6.90–7.15 ppm as a doublet, respect- of life functions. Hence, in order to understand the effect of
ively. Aromatic protons of 1,4-disubstitutedphenyl appeared the most active compound 5b on ergosterol biosynthesis, an in
at 7.15–7.72 as two different doublets. The other peaks
belonging to aromatic and aliphatic protons of variable side
chains were recorded at estimated areas. Elemental analysis
vitro assay, based on quantification of ergosterol level in fungi
was performed.
An LCMSMS based method was used for quantitative deter-
for C, H, N, and S elements were satisfactory within calcu- mination of ergosterol level of C. albicans. Before the analytical
lated values of the compounds. No more than 0.4% devi- measurements, total intracellular sterols were extracted from
ation between calculated and found results were determined, fungi as reported by Breivik and Owades.[24] Ergosterol stand-
which indicated target compounds were synthesized purely.
ard (Product No: 45480, Sigma-Aldrich, Germany) was used for
quantification of ergostrerol in both inhibitor-free (negative
control) and inhibitor including samples. The most active com-
pound 5b and reference drugs were used at 6.25, 12.5, and
25mg/mL concentrations. Ergosterol quantity in negative con-
trol samples was regarded as 100%. All concentrations were
analyzed in quadruplicate, and the results were expressed as
mean standard deviation (SD) (Figure 1).
Ergosterol quantification studies revealed that compound
5b and reference agents significantly decreased the level of
ergosterol at all tested concentrations. A concentration
dependant decrease in the ergosterol level was seen for all
tested agents. Thus, it can be clearly suggested that compounds
5e have a role in the ergosterol biosynthesis pathway.
Antifungal activity
Antifungal activity was investigated by finding minimum
inhibitory concentration (MIC) of the synthesized compounds
(5a–5i) against C. glabrata (ATCC 90030), C. krusei (ATCC
6258), C. parapsilosis (ATCC 22019) and C. albicans (ATCC
24433) comparing with fluconazole and ketoconazole as stand-
ard drugs. The MIC value of the compounds and control drugs
are summarized in Table S1 (Supplemental Mateirals).
The MIC values were generally within the range of
12.5–25 lg/mL. Most of the compounds showed significant
antifungal activity against C. albicans (ATCC 24433) and C.
krusei (ATCC 6258). In consideration of synthesized com-
pounds’ MIC values with standard drug, only the compound
5b indicated similar antifungal activity to ketoconazole and
fluconazole against C. parapsilosis (ATCC 22019) and eval-
uated as the most active derivative in the series. Observation of
very similar antifungal activity displayed by the compounds
(5a–5i) indicates that there is no important difference between
contributions of various dithiocarbamoyl moieties to antifun-
gal activity and makes consideration of the SARs very difficult.
Hence, it can be assumed that antifungal activity of the com-
pounds (5a–5i) is related to their general structural character-
istics provided by both dithiocarbamoyl moieties and N-[4-
((1H-imidazol-1-yl)methyl)phenyl]acetamide substructure.
ADME prediction
The absorption, distribution, metabolism, and excretion
(ADME) studies are critical in modern drug discovery. Early
characterization of these properties is essential for successful
drug discovery studies to eliminate compounds with
unacceptable pharmacokinetic properties. In silico ADME
and toxicological screening systems can provide an oppor-
tunity to predict performance in an in-vivo setting. Thus,
predictions of ADME properties of the all synthesized com-
pounds (5a–5i) were performed by QikProp 4.8 software.[25]
This software evaluates the ADME profiles of drug candi-
dates according to the Lipinski’s rule of five[26] and Jorgensen’s
rule of three.[27] The data of the software such as molecular
weight, log P, polar surface area (PSA), number of hydrogen
Inhibition of ergosterol biosynthesis
Most antifungal therapies target the ergosterol biosynthesis donors, number of hydrogen acceptors, number of rotatable
pathway. It is the main sterol of fungi cell membranes and is bonds and volume, are presented in Table S2 (Supplemental
necessary for fluidity, permeability and protein function[23] Materials) along with the violations of rule of three and five.