Synthesis, characterization, POM analysis and antifungal activity of novel heterocyclic chalcone derivatives containing acylated pyrazole

Article abstract of DOI:10.1007/s11164-016-2737-y

Abstract: A series of heterocyclic chalcone derivatives (4a–h) were synthesized and characterized by IR, ¹H and ¹³C NMR as well as MS. All the synthesized compounds were evaluated for their antifungal activity on Candida albicans and

Full text of DOI:10.1007/s11164-016-2737-y

Res Chem Intermed
DOI 10.1007/s11164-016-2737-y
Synthesis, characterization, POM analysis
and antifungal activity of novel heterocyclic chalcone
derivatives containing acylated pyrazole
Helmi Mohammed Al-Maqtari1 Joazaizulfazli Jamalis1
•
•
Taibi Ben Hadda2 Murugesan Sankaranarayanan3
•
•
Subhash Chander3 Noor Aisyah Ahmad1 Hasnah Mohd Sirat1
•
•
•
Ismail I. Althagafi4 Yahia Naseer Mabkhot5
•
Received: 23 July 2016 / Accepted: 6 September 2016
Ó Springer Science+Business Media Dordrecht 2016
Abstract A series of heterocyclic chalcone derivatives (4a–h) were synthesized and
characterized by IR, 1H and 13C NMR as well as MS. All the synthesized compounds were
evaluated for their antifungal activity on Candida albicans and Aspergillus niger. The
assay revealed that compounds 3d and 4f showed significant activity against both tested
fungal strains. POM analyses showed that the compounds are highly lipophyllic but present
a potential bioactivity. Moreover, they have no NH–O or N–HO intramoleculcular inter-
action which is a crucial parameter controlling solubility of compounds possessing these
encouraging pharmaceutical properties. This series gives us an important lesson in drug
design: We should take the balance of hydrosolubility/lipophilicity into consideration.
POM analyses were in agreement with the idea of coexistence of two combined antifungal
N,O and O,S-pharmacophore sites for series 4a–h. On the other hand, two coexistents and
identical N,Cl-pharmacophore sites have been identified for Fluconazole.
Electronic supplementary material The online version of this article (doi:10.1007/s11164-016-2737-y)
contains supplementary material, which is available to authorized users.
&
&
1
Joazaizulfazli Jamalis
joazaizulfazli@utm.my
Taibi Ben Hadda
taibi.ben.hadda@gmail.com
Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai,
Johor, Malaysia
2
3
LCM Laboratory, FSO, University of Mohammed Premier, Oujda 60000, Morocco
Medicinal Chemistry Research Laboratory, Department of Pharmacy, Birla Institute of
Technology and Science, Pilani, Rajasthan 333031, India
4
5
Chemistry Department, Faculty of Applied Sciences, Umm Al-Qura University, Makkah, Saudi
Arabia
Department of Chemistry, College of Science, King Saud University,
P. O. Box 2455, Riyadh 11451, Saudi Arabia
123

H. M. Al-Maqtari et al.
Graphical Abstract
Keywords Chalcone-pyrazole derivatives Á Antifungal Á Petra/Osiris/Molinspiration
(POM) analyses Á Pharmacophore site Identification
Introduction
Fungal infections are serious types of health problems infecting humans around
the world [1]. The emergence of antibiotics to fight fungi and other microbes has
resulted in the presence of pathogens that are resistant to pharmaceutical agents.
The presence of drugs such as Fluconazole, Methotrexate, Azathioprine,
Cyclosporine, Voriconazole, Itraconazole, Micafungin, Posaconazole, Flucytosine,
Anidulafungin, Caspofungin and others can help to fight against fungal infections.
Nevertheless, these drugs gave side effects when used in combination with other
drugs [2, 3].
Therefore, pyrazole derivatives are some of the compounds that can act against
fungi as they exhibit a broad range of pharmacological activities such as
antibacterial, anticancer, antifungal, anti-inflammatory, anti-oxidant and others
[4, 5]. The presence of a F–N interaction between fluoro-1 and the two nitrogen (N-
1 and N-2) atoms in the crystalline structure of Fluconazole [6–8] is an indication of
the coexistence of two combined N,F-pharmacophore sites, and the removal or
modification of this topology could obstruct or increase its various pharmacological
activities (Fig. 1).
Based on its diversity of biological activities, Flcuconazole has attracted our
attention for the synthesis of bis-armed pyrazole derivatives 4a–h (Fig. 1) instead
of mono-armed pyrazole derivatives as an antifungal drug. Previous studies
carried out by Ben Hadda et al reported that various organic compounds showed
improved antifungal activity against a wide range of fungal strains [9–12].
Encouraged by this, a series of heterocyclic bis-armed pyrazole derivatives were
synthesized by focusing on the terminal aryl electron rich with different
substituents of the phenyl ring. All the compounds were tested for their ability
to act as antifungal agents in order to develop a novel therapeutic agent for the
better treatment of fungal infections.
123

Synthesis, characterization, POM analysis and antifungal…
H
H
H
O
H
S
N
H
Br
N
H
H
H
H
H
R
H
H
Fluconazole (SD)
4a-h
Fig. 1 Structure of Flcuconazole (SD) and new chalcone derivatives containing acylated pyrazole 4a–h
Experimental
Materials and methods
Melting points (uncorrected) were determined using a Barnstead Electrothermal
9100 melting point. 1H and 13C NMR spectra (400 and 300 MHz respectively) were
recorded on a Bruker Avance II spectrometer using deuterated chloroform (CDCl3)
as solvent. Chemical shift values were given in d (ppm) scales. Infrared (IR) spectra
were recorded on a Perkin Elmer FT-IR spectrometer. The ESMS were recorded on
a MICROMASS Quattro-II LCMS system (Waters, Milford, MA, USA). Thin layer
chromatography (TLC) alumina sheets precoated with silica gel 60 F254 (0.2 mm
thickness) was used to monitor and detect the compounds, and the spots were
visualized under a UV lamp at 254 nm. All chemicals and reagents were of
analytical grade and were used without further purification.
General procedure for synthesis of chalcones (3a–h)
A mixture of desired substituted acetophenones (2a–h) (1 mol) with 5-bromo-2-
thiophenecarboxaldehyde (1) (1 mol) was dissolved in methanol (25 mL). Aqueous
potassium hydroxide (15 mL) was added dropwise to the mixture. The reaction
mixture was stirred at room temperature overnight. The solid product was filtered,
washed with water, dried to obtain the solid and then recrystallized using ethanol to
produce the corresponding chalcones (3a–h). Completion of the reaction was
monitored by TLC [13].
(E)-3-(5-bromothiophen-2-yl)-1-phenylprop-2-en-1-one (3a)
Pale yellow solid, yield: (2.01 g, 42.86 %). M.p: 72–74 °C; IR (cm-1): 3087 (C–H–
sp2), 1658 (C=O), 1590, 1420 (C=C aromatic ring); 1H NMR (400 MHz, CDCl3): d
7.08 (d, 1H, H-4, J = 4.00 Hz), 7.13 (d, 1H, H-3, J = 4.00 Hz), 7.25 (d, 1H, H-a,
J = 15.40 Hz), 7.50–7.64 (m, 3H, H-30 and H-50 and H-40), 7.84 (d, 1H, H-b,
123

H. M. Al-Maqtari et al.
J = 15.40 Hz), 7.99 for funding this Research group 8.04 (m, 2H, H-20 and H-60);
13C NMR (75 MHz, CDCl3): d 116.42, 120.94, 128.41, 128.70, 131.36, 132.41,
132.96, 136.30, 137.91, 141.94, 189.61; MS (m/z): 293.1 [M?, 100 %], 295.1
[M?2].
(E)-3-(5-bromothiophen-2-yl)-1-(4-chlorophenyl)prop-2-en-1-one (3b)
Pale yellow solid, yield: (4.99 g, 83.3 %). M.p: 129–130 °C; IR (cm-1): 3069 (C–
H–sp2), 1655 (C=O), 1590, 1420 (C=C aromatic ring); 1H NMR (400 MHz,
CDCl3): d 7.09 (d, 1H, H-4, J = 4.00 Hz), 7.14 (d, 1H, H-3, J = 4.00 Hz), 7.20 (d,
1H, H-a, J = 15.40 Hz), 7.50 (d, 2H, H-30 and H-50, J = 8.80 Hz), 7.85 (d, 1H,
H-b, J = 15.40 Hz), 7.96 (d, 2H, H-20 and H-60, J = 8.40 Hz); 13C NMR (75 MHz,
CDCl3): d 116.77, 120.29, 129.01, 129.80, 131.43, 132.71, 136.21, 136.72, 139.39,
141.75, 188.19; MS (m/z): 327.0 [M?, 100 %], 329.0 [M?2].
(E)-3-(5-bromothiophen-2-yl)-1-(4-fluorophenyl)prop-2-en-1-one (3c)
Pale yellow solid, yield: (5.78 g, 84.4 %). M.p: 100–102 °C; IR (cm-1): 3108 (C–
H–sp2), 1655 (C=O), 1587, 1426 (C=C aromatic ring); 1H NMR (400 MHz,
CDCl3): d 7.09 (d, 1H, H-4, J = 4.00 Hz), 7.14 (d, 1H, H-3, J = 4.00), 7.22 (d, 1H,
H-a, J = 15.20 Hz), 7.18–7.23 (m, 2H, H-30 and H-50), 7.85 (d, 1H, H-b,
J = 15.20 Hz), 8.02–8.08 (m, 2H, H-20 and H-60); 13C NMR (75 MHz, CDCl3):
d115.69, 115.98, 116.59, 120.38, 130.95, 131.07, 131.40, 132.59, 134.25, 136.48,
141.80, 187.84; MS (m/z): 311.0 [M?, 100 %], 313.0 [M?2].
(E)-1-(4-bromophenyl)-3-(5-bromothiophen-2-yl)prop-2-en-1-one (3d)
Pale yellow solid, yield: (8.61 g, 89.0 %). M.p: 147–149 °C; IR (cm-1): 3066 (C–
H–sp2), 1655 (C=O), 1587, 1420 (C=C aromatic ring); 1H NMR (400 MHz,
CDCl3): d 7.09 (d, 1H, H-4, J = 3.80 Hz), 7.14 (d, 1H, H-3, J = 3.80), 7.18 (d, 1H,
H-a, J = 15.20 Hz), 7.67 (d, 2H, H-30 and H-50, J = 8.80 Hz), 7.82–7.90 (m, 3H,
H-b and H-20 and H-60); 13C NMR (75 MHz, CDCl3): d 116.82, 120.24, 128.10,
129.92, 131.45, 132.00, 132.77, 136.62, 136.80, 141.73, 188.40; MS (m/z): 372.9
[M?, 100 %], 375.0 [M?2].
(E)-3-(5-bromothiophen-2-yl)-1-(4-iodophenyl)prop-2-en-1-one (3e)
Pale yellow solid, yield: (6.21 g, 92.6 %). M.p: 146–148 °C; IR (cm-1): 3090 (C–
H–sp2), 1655 (C=O), 1587, 1420 (C=C aromatic ring); 1H NMR (400 MHz,
CDCl3): d 7.09 (d, 1H, H-4, J = 3.80 Hz), 7.14 (d, 1H, H-3, J = 3.80 Hz), 7.18 (d,
1H, H-a, J = 15.20 Hz), 7.72 (d, 2H, H-30 and H-50, J = 8.80 Hz), 7.84 (d, 1H,
H-b, J = 15.20 Hz), 7.89 (d, 2H, H-20 and H-60, J = 8.80 Hz); 13C NMR (75 MHz,
CDCl3): d 100.84, 116.81, 120.22, 129.79, 131.44, 132.74, 136.78, 137.17, 137.99,
141.74, 188.71; MS (m/z): 419.0 [M?, 100 %], 420.0 [M?1], 421.0 [M?2].
123

Synthesis, characterization, POM analysis and antifungal…
(E)-3-(5-bromothiophen-2-yl)-1-(4-methoxyphenyl)prop-2-en-1-one (3f)
Pale yellow solid, yield: (6.11 g, 90.0 %). M.p: 142–143 °C; IR (cm-1): 3075 (C–
1
H–sp2), 1655 (C=O), 1590, 1512, 1426 (C=C aromatic ring); H NMR (400 MHz,
CDCl3): d 3.90 (s, 3H, CH3), 7.01 (d, 2H, H-30 and H-50, J = 8.80 Hz), 7.07 (d, 1H,
H-4, J = 4.00 Hz), 7.11 (d, 1H, H-3, J = 4.00 Hz), 7.27 (d, 1H, H-a,
J = 15.20 Hz), 7.83 (d, 1H, H-b, J = 15.20 Hz), 8.03 (d, 2H, H-20 and H-60,
J = 9.20); 13C NMR (75 MHz, CDCl3): d 55.53, 113.90, 115.95, 120.83, 130.74,
130.80, 131.28, 132.05, 135.51, 142.14, 163.54, 187.77; MS (m/z): 323.2 [M?,
100 %], 325.0 [M?2].
(E)-3-(5-bromothiophen-2-yl)-1-p-tolylprop-2-en-1-one (3g)
Pale yellow solid, yield: (5.60 g, 82.8 %). M.p: 91–93 °C; IR (cm-1): 3078(C–H–
sp2), 1652 (C=O), 1587, 1426 (C=C aromatic ring); 1H NMR (400 MHz, CDCl3): d
7.08 (d, 1H, H-4, J = 4.00 Hz), 7.12 (d, 1H, H-3, J = 4.00 Hz), 7.25 (d, 1H, H-a,
J = 15.40 Hz), 7.33 (d, 2H, H-30 and H-50, J = 8.00 Hz), 7.83 (d, 1H, H-b,
J = 15.40 Hz), 7.93 (d, 2H, H-20 and H-60, J = 8.40 Hz); 13C NMR (75 MHz,
CDCl3): d 21.73, 116.16, 120.99, 128.55, 129.40, 131.31, 132.21, 135.33, 135.88,
142.06, 143.87, 189.05; MS (m/z): 307.2 [M?, 100 %], 309.2 [M?2].
(E)-3-(5-bromothiophen-2-yl)-1-(4-nitrophenyl)prop-2-en-1-one (3h)
Yellow solid, yield: (8.43 g, 77.9 %). M.p: 166–167 °C; IR (cm-1): 3096 (C–H–
1
sp2), 1655 (C=O), 1577, 1515, 1423 (C=C aromatic ring); H NMR (400 MHz,
CDCl3): d 7.12 (d, 1H, H-4, J = 3.80 Hz), 7.19 (d, 1H, H-3, J = 3.80 Hz), 7.20 (d,
1H, H-a, J = 15.40 Hz), 7.88 (d, 1H, H-b, J = 15.40 Hz), 8.15 (d, 2H, H-30 and
H-50, J = 8.80 Hz), 8.38 (d, 2H, H-20 and H-60, J = 9.20 Hz); 13C NMR (75 MHz,
CDCl3): d 117.75, 119.91, 123.93, 129.32, 131.64, 133.51, 138.02, 141.35, 142.73,
150.11, 187.99; MS (m/z): 338.3 [M?, 100 %], 340.1 [M?2].
General procedure for synthesis of pyrazolines derivatives (4a–h)
A mixture of chalcones (3a–h) (1 mol) was refluxed with appropriate hydrazine
hydrate (2.5 mol) in glacial acetic acid overnight. The reaction mixture was cooled
and poured into crushed ice, then the obtained precipitate was filtered off, washed,
and dried to give compounds (4a–h). The progress of the reaction was checked by
TLC [14].
1-(5-(5-bromothiophen-2-yl)-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl)ethanone (4a)
Cream solid, yield: (0.63 g, 60.1 %). M.p: 112–115 °C; IR (cm-1): 3072(C–H-sp2),
1
2929 (C–H sp3), 1643 (C=O), 1596 (C=N), 1440 (C=C aromatic ring); H NMR
(400 MHz, CDCl3): d 2.40 (s, 3H, H-1), 3.35 (dd, 1H, H-6a, J = 4.40 Hz,
J = 17.60 Hz), 3.73 (dd, 1H, H-6b, J = 17.60 Hz, J = 11.20 Hz), 5.83 (dd, 1H,
H-7, J = 4.00 Hz, J = 11.60 Hz), 6.80 (d, 1H, H-‘’4, J = 4.00 Hz), 6.89 (d, 1H,
123

H. M. Al-Maqtari et al.
H-‘‘3, J = 4.00 Hz), 7.45–7.79 (m, 5H, Ar–H); 13C NMR (75 MHz, CDCl3): d
21.96, 41.46, 55.28, 111.60, 125.04, 126.62, 128.82, 129.45, 130.58, 131.04,
145.57, 153.84, 169.05; MS (m/z): 349.1 [M?, 100 %], 351.1 [M?2].
1-(5-(5-bromothiophen-2-yl)-3-(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-1-
yl)ethanone (4b)
Cream solid, yield: (0.83 g, 72.2 %). M.p: 120–123 °C; IR (cm-1): 3092(–C–H–
1
sp2), 2916 (–C–H–sp3), 1642 (C=O), 1590 (C=N), 1424 C=C aromatic ring). H
NMR (400 MHz, CDCl3): d 2.40 (s, 3H, H-1), 3.31 (dd, 1H, H-6a, J = 4.40 Hz,
J = 1 8.00 Hz), 3.70 (dd, 1H, H-6b, J = 11.60 Hz, J = 17.60 Hz), 5.83 (dd, 1H,
H-7, J = 4.00 Hz, J = 11.60 Hz), 6.80 (d, 1H, H-‘’4, J = 3.60 Hz), 6.90 (d, 1H,
H-‘‘3, J = 4.00 Hz), 7.43 (d, 2H, H-‘3 and H-‘5, J = 8.80 Hz), 7.70 (d, 2H, H-‘2
and H-‘6, J = 8.80 Hz); 13C NMR (75 MHz, CDCl3): d 21.95, 41.38, 55.44,
111.69, 125.12, 127.84, 129.11, 129.49, 129.54, 136.57, 145.35, 152.69, 169.03;
MS (m/z): 383.1 [M?, 100 %], 385.1 [M?2].
1-(5-(5-bromothiophen-2-yl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-
yl)ethanone (4c)
Cream solid, yield: (1.02 g, 92.6 %). M.p: 118–120 °C; IR (cm-1): 3071(C–H–sp2),
1
2971 (C–H sp3), 1639 (C=O), 1605 (C=N), 1511, 1440 (C=C aromatic ring). H
NMR (400 MHz, CDCl3): d 2.40 (s, 3H, H-1), 3.33 (dd, 1H, H-6a, J = 4.00 Hz,
J = 17.60 Hz), 3.70 (dd, 1H, H-6b, J = 11.20 Hz, J = 17.60 Hz), 5.84 (dd, 1H,
H-7, J = 4.00 Hz, J = 11.60 Hz), 6.80 (d, 1H, H-‘’4, J = 3.60 Hz), 6.89 (d, 1H,
H-‘‘3, J = 3.60 Hz), 7.10–7.80 (m, 4H, Ar–H); 13C NMR (75 MHz, CDCl3): d
21.95, 41.53, 55.38, 111.65, 115.88, 116.18, 125.08, 128.57, 128.68, 129.48,
145.44, 152.77, 168.99; MS (m/z): 367.2 [M?, 100 %], 369.2 [M?2].
1-(3-(4-bromophenyl)-5-(5-bromothiophen-2-yl)-4,5-dihydro-1H-pyrazol-1-
yl)ethanone (4d)
Cream solid, yield: (1.21 g, 94.2 %). M.p: 139–141 °C; IR (cm-1): 3087(C–H–sp2),
1
2917 (C–H sp3), 1640 (C=O), 1587 (C=N), 1444 (C=C aromatic ring). H NMR
(400 MHz, CDCl3): d 2.40 (s, 3H, H-1), 3.30 (dd, 1H, H-6a, J = 4.40 Hz,
J = 17.60 Hz), 3.70 (dd, 1H, H-6b, J = 11.60 Hz, J = 17.60 Hz), 5.84 (dd, 1H,
H-7, J = 4.00 Hz, J = 11.60 Hz), 6.79 (d, 1H, H-‘’4, J = 3.60 Hz), 6.89 (d, 1H,
H-‘‘3, J = 3.60 Hz), 7.57–7.65 (m, 4H, Ar–H); 13C NMR (75 MHz, CDCl3): d
21.94, 41.33, 55.46, 111.70, 124.93, 125.13, 128.03, 129.49, 129.98, 132.06,
145.33, 152.78, 169.06; MS (m/z): 429.1 [M?1, 100 %], 431.0 [M?3].
1-(5-(5-bromothiophen-2-yl)-3-(4-iodophenyl)-4,5-dihydro-1H-pyrazol-1-
yl)ethanone (4e)
Cream solid, yield: (0.76 g, 80.0 %). M.p: 128–131 °C; IR (cm-1): 3081 (C–H–
1
sp2), 2914 (C–H sp3), 1640 (C=O), 1593 (C=N), 1447 (C=C aromatic ring). H
123

Synthesis, characterization, POM analysis and antifungal…
NMR (400 MHz, CDCl3): d 2.40 (s, 3H, H-1), 3.30 (dd, 1H, H-6a, J = 4.00 Hz,
J = 1 7.60 Hz), 3.70 (dd, 1H, H-6b, J = 11.20 Hz, J = 17.60 Hz), 5.80 (dd, 1H,
H-7, J = 4.40 Hz, J = 11.60 Hz), 6.79 (d, 1H, H-‘’4, J = 3.60 Hz), 6.89 (d, 1H,
H-‘‘3, J = 4.00 Hz), 7.48 (d, 2H, H-‘3 and H-‘5, J = 8.00 Hz), 7.80 (d, 2H, H-‘2
and H-‘6, J = 8.40 Hz); 13C NMR (75 MHz, CDCl3): d 21.97, 41.22, 55.43, 96.92,
111.69, 125.12, 128.07, 129.49, 130.52, 137.99, 145.33, 152.89, 169.01; MS (m/z):
475.0 [M?, 100 %], 477.0 [M?2].
1-(5-(5-bromothiophen-2-yl)-3-(4-methoxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl)
ethanone (4f)
Cream solid, yield: (0.93 g, 81.7 %). M.p: 108–110 °C; IR (cm-1): 3089 (C–H–
1
sp2), 2919 (C–H sp3), 1645 (C=O), 1590 (C=N), 1427 (C=C aromatic ring). H
NMR (400 MHz, CDCl3): d 2.39 (s, 3H, H-1), 3.30 (dd, 1H, H-6a, J = 4.00 Hz,
J = 17.60 Hz), 3.68 (dd, 1H, H-6b, J = 11.60 Hz, J = 17.60 Hz), 3.87 (s, 3H,
H-‘7), 5.80 (dd, 1H, H-7, J = 3.60 Hz, J = 11.20 Hz), 6.79 (d, 1H, H-‘’4,
J = 4.00 Hz), 6.87 (d, 1H, H-‘‘3, J = 4.00 Hz), 6.96 (d, 2H, H-‘3 and H-‘5,
J = 8.80 Hz), 7.70 (d, 2H, H-‘2 and H-‘6, J = 8.80 Hz); 13C NMR (75 MHz,
CDCl3): d 21.95, 41.52, 55.14, 55.44, 111.49, 114.21, 123.64, 124.95, 128.24,
129.41, 145.73, 153.65, 161.49, 168.82; MS (m/z): 379.1[M?, 100 %],
381.1[M?2].
1-(5-(5-bromothiophen-2-yl)-3-p-tolyl-4,5-dihydro-1H-pyrazol-1-yl)ethanone (4g)
Cream solid, yield: (0.71 g, 65.1 %). M.p: 119–120 °C; IR (cm-1): 3077(C–H–sp2),
1
2916 (C–H–sp3), 1642 (C=O), 1590 (C=N), 1444 (C=C aromatic ring); H NMR
(400 MHz, CDCl3): d 2.39–2.46 (s, 6H, H-1 and H-‘7), 3.33 (dd, 1H, H-6a,
J = 4.00 Hz, J = 17.60 Hz), 3.70 (dd, 1H, H-6b, J = 17.60 Hz, J = 11.40 Hz),
1
5.81 (dd, H, H-7, J = 4.00 Hz, J = 11.40 Hz), 6.80 (d, 1H, H-‘’4, J = 4.00 Hz),
6.89 (d, 1H, H-‘‘3, J = 3.60 Hz), 7.27 (d, 2H, H-‘3 and H-‘5, J = 8.00 Hz), 7.66
(d, 2H, H-‘2 and H-‘6, J = 8.00 Hz); 13C NMR (75 MHz, CDCl3): d 21.55, 21.96,
41.49, 55.17, 111.54, 124.99, 126.58, 128.25, 129.42, 129.52, 140.98, 145.66,
153.97, 168.97; MS (m/z): 363.1 [M?, 100 %], 365.1 [M?2].
1-(5-(5-bromothiophen-2-yl)-3-(4-nitrophenyl)-4,5-dihydro-1H-pyrazol-1-
yl)ethanone (4h)
Cream solid, yield: (0.86 g, 72.7 %). M.p: 132–134 °C; IR (cm-1): 3080 (C–H–
1
sp2), 2919 (C–H–sp3), 1642 (C=O), 1590 (C=N), 1441 (C=C aromatic ring); H
NMR (400 MHz, CDCl3): d 2.40 (s, 3H, H-1), 3.38 (dd, 1H, H-6a, J = 4.20 Hz,
J = 17.60 Hz), 3.77 (dd, 1H, H-6b, J = 11.60 Hz, J = 17.60 Hz), 5.89 (dd, 1H,
H-7, J = 4.20 Hz, J = 11.60 Hz), 6.82 (d, 1H, H-‘’4, J = 4.00 Hz), 6.91 (d, 1H,
H-‘‘3, J = 4.00 Hz), 7.92 (d, 2H, H-‘3 and H-‘5, J = 8.80 Hz), 8.32 (d, 2H, H-‘2
and H-‘6, J = 8.80 Hz); 13C NMR (75 MHz, CDCl3): d 21.99, 41.25, 55.90,
111.95, 124.12, 125.38, 127.28 129.58, 137.03, 144.86, 148.60, 151.35, 169.24; MS
(m/z): 394.1 [M?, 100 %], 396.0 [M?2].
123

H. M. Al-Maqtari et al.
Antifungal screening
The synthesized compounds were screened for in vitro antifungal activity against
two fungal strains, Candida albicans (MTCC 3958) and Aspergillus niger (MTCC
9933). Antifungal activity of the test compounds was expressed in terms of ZOI
(zone of Inhibition) and MIC (minimum inhibitory concentration). Fluconazole was
used as the reference drug for the study and DMSO was used as a negative control.
Tests were performed in triplicate with the following procedure as described briefly.
Autoclaved suitable growth media (Malt Yeast Agar for Candida albicans and
Czapek Yeast Extract Agar-CYA for Aspergillus niger) were poured into autoclaved
Petri plates. Further, the agar plates were swabbed with 100 ll inocula of each test
organism under aseptic conditions. After the adsorption, wells of 6 mm diameter
were made by a sterile metallic borer and the solutions of the working compounds
(128 lg/20 lL) was poured into the wells. The plates were incubated at 28°C for
48 h and the ZOI was calculated. Similarly, the MIC values were calculated using
the broth double-dilution method for each compound, taking 100 ll inoculum of
each fungal culture, after incubation at 28°C for 48 h [15, 16].
POM analyses
On the basis of POM analyses, we can conclude that the synthesized compounds are
suitable for antiviral/antifungal activity as they possess (Xd-–Yd-) pharmacophoric
sites due to the presence of electronegative heteroatoms. It can also be hypothesized
that the difference in charge between X and Y of the same dipolar pharmacophoric
site should facilitate the inhibition of bacteria more than viruses and fungi
[6–12, 17–22].
Results and discussion
Chemistry
The synthesis of chalcones (3a–h) was carried out by the condensation of
substituted acetophenones (2a–h) with 5-bromo-2-thiophenecarboxaldehyde in the
presence of sodium hydroxide and methanol. Pyrazoline derivatives (4a–h) were
synthesized by the cyclization reaction of chalcones (3a–h) with hydrazine hydrate
in the presence of glacial acetic acid (Scheme 1).
Chalcones (3a–h) were characterized by IR, 1H NMR, 13C NMR and MS. The IR
spectrum of the chalcones (3a–h) showed a characteristic band for –C–H–sp2
stretching of the aromatic ring at 3010–3080 cm-1. The chalcones (3a–h) revealed
bands at 1650–1675 cm-1 indicating the presence of a carbonyl group (–C=O). The
low frequency for carbonyl is due to the conjugation of the olefinic group with those
on the pi-electrons on the benzene ring in the enone moiety. The compounds (3a–h)
also displayed absorption bands corresponding to the C=C aromatic ring at
1580–1600 and 1410–1430 cm-1. The structure of compounds (3a–h) was
1
confirmed by H NMR spectra. Two vinylic protons of H-a and H-b appeared as
123

Synthesis, characterization, POM analysis and antifungal…
H
O
2'
3
O
O
4
NaOH aq.
S
+
S
6'
R
EtOH
R
Br
Br
1
2a-h
3a-h
1
O
O
CH3
CH3
S
N
N
Br
7
HO
H2N-NH2
6
2e, 3e, 4e: R = I,
R
2a, 3a, 4a: R = -H,
2b, 3b, 4b: R = Cl,
2c, 3c, 4c: R = F,
2d, 3d, 4d: R = Br,
4a-h
2f, 3f, 4f: R = OMe,
2g, 3g, 4g: R = Me,
2h, 3h, 4h: R = NO2
Scheme 1 Synthesis of chalcone (3a–h) and pyrazole derivatives (4a–h)
doublet at 7.20 ppm and 7.85 ppm, respectively. Trans-configuration of the
chalcones (3a–h) was confirmed by the large coupling constant of olefinic protons
(15.2–15.6 Hz). In the 13C NMR spectra, the appearance signal in the low field
region of d 180–190 was assigned to the carbonyl group.
The IR spectrum of compounds (4a–h) exhibited the characteristic bands around
1570–1595 cm-1 and 1640–1660 cm-1 which indicated the presence of –C=N and
carbonyl C=O groups, respectively. The IR of the compounds (4a–h) also revealed
characteristic bands at 2910–2925 cm-1 due to C–H sp3 stretching of the –COCH3
1
group. The H NMR spectra of compounds 4a–h showed the pyrazoline ring CH2
protons (H-6a and H-6b) resonated as a pair of doublet of doublets at d 3.31 ppm
(J = 4.30–4.45 Hz, J = 18.00–18.15 Hz) and d 3.70 ppm (J = 11.40–11.60 Hz,
J = 18.00–18.15 Hz), respectively. The Hx-7 also appeared as a doublet of doublets
at d 5.83 (J = 4.30–4.45 Hz, J = 11.40–11.60 Hz). The singlet signals integrating
for three protons in the high field region, d 2.3–2.5 ppm, was assigned to –CH3
protons. The 13C NMR supported the N-acetyl group C-1 and C-2 carbon atoms at d
21.70–21.95 and d 165–170, respectively.
The hydrophilicity character of each compound has been expressed in terms of its
cLogP value since it has been established that the absorption or permeation is
greatly affected by this quantity (the value of cLogP). Accordingly, when the value
of cLogP is higher than 5, the absorption or permeation decreases (Table 1) [6–12].
Antifungal activity
Among the tested compounds, 3d, 3f and 4f showed significant inhibition against
C.albicans while compounds 3g, 4g and 4h exhibited moderate inhibition against C.
albicans. Compounds 3c, 3d, 3h, 4a, 4b, 4d, 4f and 4g showed significant inhibition
against A.niger. The compounds 3a and 3g possessed moderate inhibition against A.
niger. Both compounds 3d and 4f gave significant activity against both of the tested
fungal strains. Detail of the result is shown in Table 2.
123

H. M. Al-Maqtari et al.
Table 1 Structure pyrazole derivatives 4a–h; the hypothetic N,O-pharmacophore site (green color) is in
cis/cisoidal conformation (Molinspiration Optimization)
Compound Optimized structure
cLogP Compound Optimized structure
cLogP
4a
4.46
4e
5.55
4b
4c
4d
5.14
4.63
5.27
4f
4.52
4.91
4.42
4g
4h
Results from MIC values revealed that all the bis-armed pyrazole derivatives
possess antifungal activity in the range of 32 to 130 lg/mL against the two selected
fungi strains. Among all heterocyclic pyrazole derivative bearing an electron donor
123

Synthesis, characterization, POM analysis and antifungal…
a
Table 2 Antifungal activity of compounds 3a–h, 4a–h and standard drug SD (Fluconazole)
Compound
R
MW (g/mole)
Candida albicansa
Aspergillus nigera
Z.I. (mm)
MIC (lg/mL)
Z.I. (mm)
MIC (lg/mL)
3a
3b
3c
3d
3e
3f
H
293
327
311
372
419
323
307
338
349
384
367
428
475
379
363
394
306
–
–
10
–
[128
–
Cl
–
–
F
–
–
14
13
–
[64
[128
–
Br
12
–
[64
–
I
OCH3
CH3
NO2
H
13
11
–
[64
[128
–
–
–
3g
3h
4a
4b
4c
4d
4e
4f
10
12
14
14
–
[128
[64
32
–
–
Cl
–
–
64
F
–
–
–
Br
9
[128
–
15
–
[32
–
I
–
OCH3
CH3
NO2
–
13
10
11
18
[64
[128
[128
16
13
12
–
[64
[128
–
4g
4h
SDb
a
20
8
Z.I. Zone of Inhibition (mm)
b
SD Standard Drug (Fluconazole)
(–): Not Active
group, OMe (4f) exhibited the highest antifungal activity against both fungal strains
(MIC = 64 lg/mL). This is in agreement with reported work by Ben Hadda et al.,
in which compounds with U geometry containing negatively charged groups
emerged as the most potent antifungal and antiviral drugs [17–22]. However, the
introduction of more electron-donor halogen groups such as iodine at the same
position of the phenyl ring of heterocyclic pyrazole, especially compound (4e)
caused a decrease in antifungal activity (no MIC) compared to the unsubstituted
pyrazole derivative (4a) with (MIC = 32 lg/mL)
POM analyses
Petra/Osiris/Molinspiration analysis (POM) [17–22] is used to identify and indicate
the type of pharmacophore site that affects biological activity with a change in the
chemical substitution. POM is a well-known and simple bioinformatics but efficient
method that has been used regularly to produce the two-dimensional models. It has
the ability to predict the biological activities of the molecules and to represent the
relationships between steric/electrostatic property as well as biological activity in
the form of pharmacophore site which gives the key features on not only the ligand–
receptor interaction but also on the topology of the receptor [17–22]. Potential
antifungal N,O and O,S-pharmacophore sites is shown in Scheme 2.
123

H. M. Al-Maqtari et al.
Scheme 2 Potential antifungal N,O and O,S-pharmacophore sites
Table 3 shows the results of theoretical drug scores of tested compounds
calculated with the aid of the Molinspiration program. Our findings concerning the
screened molecules revealed that most of these compounds are moderate or not
active (Table 3). They present low and negative drug scores and cannot be utilized
as therapeutic agents if we take the five Lipinski rules. In fact, structures of the
investigated biotargets inhibitors are supposed to present no violation and good
bioavailability (cLogP \ 5), but these compounds are the subject of a violation
(VIOL = 1).
Thus, most of them are moderately or inactive. These analyses reveal that the
compounds are highly lipophyllic but present a potential bioactivity. Moreover, they
have no NH–O or N–HO intramoleculcular interactions which are a crucial
parameter of controlling the solubility of compounds possessing these encouraging
pharmaceutical properties. This series gives us an important lesson in drug design:
We should take the balance of hydrosolubility/lipophicity into consideration
(Table 3).
Our virtual POM screening results show clearly that Fluconazole (SD) is far
away to be compared with the series 4a–h because it presents better physico-
chemical properties than our candidate drugs. The cLogP of SD is equal to -0.14
which constitutes a crucial parameter of bioavailability. This can be attributed to the
existence of a hydroxyl group on the central carbon of SD (Fig. 1). In contrast to
SD, the series 4a–h has no hydrosolubilisator OH group (OHN = 0). So all eight of
the new compounds have cLogP, without the acceptable criteria (cLogP ꢀ 5; not
approximately equal to 5).
As the molecular weight of 8 of the 13 tested molecules 3, 4 is
293–372 \ 500 g/mole, it is possible to realize a more beneficial chemical
modification (hydroxylation) in the goal to make more potentially active
analogues with acceptable solubility, drug-likeness and drug score. The actual
drug scores of most of the compounds are less encouraging (less positive values of
DS), as shown in Table 3. Thus, the cLogP and drug score parameters should be
taken into consideration and serve as a guide for further enzymatic screening
investigations.
123

Synthesis, characterization, POM analysis and antifungal…
Table 3 Molinspiration calculations of compounds 3a–h and 4a–h
Compound Molecular propertiesa
Bioactivity scoresb
TPSA ONH VIOL VOL GPCR ICM
KI
NRL
PI
EI
3a
3b
3c
3d
3e
3f
17
17
17
17
17
26
17
63
33
34
33
33
33
42
33
79
82
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
210
224
215
228
234
236
227
234
258
272
263
276
282
284
275
282
249
-0.78 -0.42 -0.87 -0.91 -0.77 -0.32
-0.68 -0.38 -0.79 -0.81 -0.73 -0.32
-0.67 -0.39 -0.71 -0.75 -0.70 -0.29
-0.78 -0.45 -0.81 -0.90 -0.78 -0.35
-0.67 -0.37 -0.74 -0.74 -0.76 -0.35
-0.65 -0.45 -0.71 -0.69 -0.65 -0.29
-0.74 -0.48 -0.82 -0.83 -0.75 -0.35
-0.71 -0.40 -0.76 -0.73 -0.68 -0.35
-0.90 -1.26 -1.27 -1.19 -0.90 -0.51
-0.83 -1.21 -1.20 -1.11 -0.87 -0.53
-0.81 -1.22 -1.14 -1.06 -0.85 -0.51
-0.91 -1.27 -1.22 -1.18 -0.91 -0.55
-0.82 -1.21 -1.16 -1.06 -0.90 -0.55
-0.81 -1.23 -1.14 -1.02 -0.81 -0.52
-0.87 -1.28 -1.22 -1.12 -0.89 -0.55
3g
3h
4a
4b
4c
4d
4e
4f
4g
4h
SDc
a
-0.89 -1.16 -1.20 -1.6
0.06 -0.04 -0.10 -023
-0.86 -0.57
-0.17 0.04
TPSA Total of polar surface area, ONH OH–N or O–HN interraction, VOL volume
b
GPCR GPCR ligand, ICM ion channel modulator, KI kinase inhibitor, NRL nuclear receptor ligamd,
PI protease inhibitor, EI enzyme inhibitor
c
SD standard drug (Fluconazole)
miLogP
TPSA
1.59
93.80
380.23
1
GPCR ligand
-0.19
-0.26
0.22
Ion channel modulator
Kinase inhibitor
MW
nOHNH
nviolations
volume
Nuclear receptor ligand
Protease inhibitor
Enzyme inhibitor
-0.22
-0.38
0.25
0
264.56
Fig. 2 Molecules in perspective
Conclusion
A series of heterocyclic chalcone derivatives containing acylated pyrazole and
thiophene groups have been successfully synthesized in good yields. The potential
bioactive compounds were evaluated for their antifungal activity. The results
showed that compound 4f exerts significant activity against C. albicans compared to
compounds 4 and 4h which exhibited moderate inhibition against C. albicans. Since
this is a preliminary study and the number of fungal strains used here is limited, this
123

H. M. Al-Maqtari et al.
study should be extended to other strains. For example, compounds 4b, 4g, 4f, and
4d, showed significant activity against A. niger. Two compounds, 3d and 4f, showed
significant activity against both the tested fungal strains. In future, this series of bis-
armed pyrazoles need to be further modified (Fig. 2) and tested on a wide range of
fungal and viral strains. All the tested compounds were filtered according to the
POM platform and Lipinski rules and all had problems passing the filter. In addition,
they showed varied physicochemical properties according to their ADME
descriptors.
Acknowledgments The authors wish to thank the Ministry of Higher Education (MOHE) for funding
this research under the Research University Grant (RUP) with vote no 05H95 and Fundamental Research
Grant Scheme (FRGS) of vote numbers 4F448. T.B.H. and Y.N.M. would like to extend their sincere
appreciation to the Deanship of Scientific Research at king Saud University for funding this Research
group No (PRG-1437-29).
References
1. Pilmis B, Puel A, Lortholary O, Lanternier F. Available online 26 May 2016. In press. doi:10.1016/j.
cmi.2016.05.016
2. Rossi S (ed.), Adelaide: Australian Medicines Handbook, (2006). ISBN 0-9757919-2-3
3. M. Zervos, J. Silverman, F. Meunier, Infect. Dis. Clin. Prac. 3, 94–101 (1994)
4. P. Ali, J. Meshram, J. Sheikh, V. Tiwari, R. Dongre, T. Ben Hadda, Med. Chem. Res. 21, 157–164
(2010)
5. M.F. Khan, M.M. Alam, G. Verma, W. Akhtar, M. Akhter, M. Shaquiquzzaman, Eur. J. Med. Chem.
120, 170–201 (2016)
6. J. Kastelic, N. Lah, D. Kikelj, I. Leban, Acta Cryst. C67, o370–o372 (2011)
7. T. Ben Hadda, R. Mouhoub, R. Jawarkar, V. Masand, I. Warad, Med Chem Res. 22, 2437–2445
(2013)
8. G. Dutkiewicz, C.S. Kumar, H.S. Yathirajan, B. Narayana, M. Kubicki, Acta Cryst. E66, o2568
(2010)
¨
9. S. Tighadouni, S. Radi, M. Sirajuddin, M. Akkurt, N. Ozdemir, M. Ahmad, Y.N. Mabkhot, T. Ben
Hadda, J. Chem. Soc. Pak. 38, 157–165 (2016)
10. T. Ben Hadda, F.Z. Khardli, M. Mimouni, M. Daoudi, A. Kerbal, H.S. Zamora, N. Gandhare, A.
Parvez, Phosphorus Sulfur Silicon Relat. Elem. 189, 753–761 (2014)
11. Y.N. Mabkhot, F.D. Aldawsari, S.S. Al-Showiman, A. Barakat, T. Ben Hadda, M.S. Mubarak, S.
Naz, Z. Ul-Haq, A. Rauf, Molecules 20, 1824–1841 (2015)
12. Z.H. Chohan, M.H. Youssoufi, A. Jarrahpour, T. Ben Hadda, Eur. J. Med. Chem. 45, 1189–1199
(2010)
13. H.M. Al-Maqtari, J. Jamalis, H.M. Sirat, Jurnal Teknologi. 77, 55–59 (2015)
14. G. Tarrago, C. Marzin, O. Najimi, V. Pellegrin, J. Org. Chem. 55, 420–425 (1990)
15. S. Magaldi, S. Essayag, C. Capriles, C. Perez, M.T. Colella, C. Olaizola, Y. Ontiveros, Int. J. Infect.
8, 39–45 (2004)
16. S. Chander, P. Ashok, Y.T. Zheng, P. Wang, K.S. Raja, A. Taneja, S. Murugesan, Bioorg. Chem. 64,
66–73 (2016)
17. Y.N. Mabkhot, A. Alatibi, N. El-sayed, N. Kheder, A. Wadood, A. Rauf, S. Bawazeer, S. Al-
Showiman, T. Ben Hadda, Molecules 21, 222–230 (2016)
18. T. Ben Hadda, Z.K. Genc, V.H. Masand, N. Nebbache, I. Warad, S. Jodeh, M. Genc, Y.N. Mabkhot,
A. Barakat, H. Salgado-Zamora, Acta Chim. Slov. 62, 679–688 (2015)
19. M.H. Youssoufi, P.K. Sahu, P.K. Sahu, D.D. Agarwal, A. Mushtaq, M. Messali, S. Lahsasni, T. Ben
Hadda, Med. Chem. Res. 24, 2381–2392 (2015)
20. Y.N. Mabkhot, A. Barakat, S. Yousuf, M.I. Choudhary, W. Frey, T. Ben Hadda, M.S. Mubarak,
Bioorg. Med. Chem. 22, 6715–6725 (2014)
123

Synthesis, characterization, POM analysis and antifungal…
21. S. Lahsasni, T. Ben Hadda, V. Masand, N.B. Pathan, A. Parvez, I. Warad, U. Shaheen, A. Bader, M.
Aljofan, Res. Chem. Intermed. 41, 5121–5513 (2015)
22. D.T. Mahajan, V.H. Masand, K.N. Patil, T. Ben Hadda, R.D. Jawarkar, S.D. Thakur, V. Rastija,
Bioorg. Med. Chem. Lett. 22, 4827–4835 (2012)
123