Replacement of the Methylene of Dihydrochalcones with Oxygen: Synthesis and Biological Evaluation of 2-Phenoxyacetophenones

Article abstract of DOI:10.1111/j.1747-0285.2012.01432.x

With the aim of finding new bioactive compounds, a series of phenoxyacetophenone derivatives 2 were designed and synthesized as oxygen analogs of dihydrochalcones. Also, phenoxyacetophenones were converted to (Z)-oxime derivatives 3 and their geometry wer

Full text of DOI:10.1111/j.1747-0285.2012.01432.x

ª 2012 John Wiley & Sons A/S
doi: 10.1111/j.1747-0285.2012.01432.x
Chem Biol Drug Des 2012
Research Article
Replacement of the Methylene of
Dihydrochalcones with Oxygen: Synthesis and
Biological Evaluation of 2-Phenoxyacetophenones
Mahsa Ansari1, Saeed Emami2,*,
potential use as drugs, the target compounds were
evaluated in their drug-like properties. The in silico
Mohammad A. Khalilzadeh3, Malek T.
values of molecular descriptors for bioactive com-
Maghsoodlou1, Alireza Foroumadi4,
pounds 2a and 3d revealed that these compounds
Mohammad A. Faramarzi5, Nasrin Samadi6
and Sussan K. Ardestani7
are within the range set by Lipinski’s ’Rule of 5’ and
show no violation of these rules. Moreover, bio-
active compounds 2a and 3d are supposed to be
non-mutagenic and non-tumorigenic, with no irri-
tating or reproductive effects.
1Department of Chemistry, University of Sistan and Baluchestan,
P.O. Box 98135-674, Zahedan, Iran
2Department of Medicinal Chemistry and Pharmaceutical Sciences
Research Center, Faculty of Pharmacy, Mazandaran University of
Medical Sciences, Sari, Iran
Key words: acetophenone derivatives, antifungal activity, antileish-
manial activity, dihydrochalcones, oximes, promastigotes
3Department of Chemistry, Science and Research Branch, Islamic
Azad University, Mazandaran, Iran
Received 24 January 2012, revised 13 May 2012 and accepted for pub-
lication 5 June 2012
4Department of Medicinal Chemistry, Faculty of Pharmacy and
Pharmaceutical Sciences Research Center, Tehran University of
Medical Sciences, Tehran, Iran
Dihydrochalcones, the reduced form of chalcones, are a subclass of
the flavonoids that occur widely in natural products and are impor-
tant intermediates for many pharmaceutical drugs (1). Dihydrochal-
cones have been reported to possess various biological activities
and have received considerable attention as promising anti-inflam-
matory and cancer chemopreventive agents (2,3). Generally, the
antifungal activity of flavonoids has been reported previously (4).
Among their different classes, dihydrochalcones have been shown
to possess promising antifungal activity (5–7).
5Department of Pharmaceutical Biotechnology, Faculty of Pharmacy
and Biotechnology Research Center, Tehran University of Medical
Sciences, Tehran, Iran
6Department of Drug and Food Control, Faculty of Pharmacy and
Pharmaceutical Quality Assurance Research Center, Tehran
University of Medical Sciences, Tehran, Iran
7Institute of Biochemistry and Biophysics, Department of
Biochemistry, University of Tehran, P.O. Box 13145-1384, Tehran, Iran
*Corresponding author: Saeed Emami, sd_emami@yahoo.com
Recently, a series of synthetic and naturally occurring chalcone-like com-
pounds have been reported to have antileishmanial activity in a number
of in vitro and in vivo assays. Hermoso et al. (8) described antileishma-
nial activities of dihydrochalcones from Piper elongatum and synthetic-
related compounds against Leishmania braziliensis, Leishmania tropica
and Leishmania infantum. Also, a number of chromeno dihydrochal-
cones, containing 2¢,2¢-dimethyl benzopyran system, were tested
against extracellular promastigotes of Leishmania donovani and intra-
cellular amastigotes residing within murine macrophages (9,10).
With the aim of finding new bioactive compounds,
a
series of phenoxyacetophenone derivatives 2
were designed and synthesized as oxygen analogs
of dihydrochalcones. Also, phenoxyacetophenones
were converted to (Z)-oxime derivatives 3 and their
geometry were characterized by 1H-NMR spectros-
copy. The in vitro antifungal activity of compounds
2 and 3 was evaluated against Candida albicans,
Candida glabrata, Saccharomyces cerevisiae, and
Aspergillus niger using micro-dilution method. In
general, oxime derivative 3d containing 4-fluoro-
phenoxy moiety showed comparable or more
Moreover, the results of previous studies support the fact that the
pharmacophore contains two aromatic rings, and the propanone
chain just functions as a spacer and that the ability to inhibit para-
site growth apparently depends on the presence and ratio of lipo-
philic ⁄ hydrophilic substituents at both aromatic rings (8,11,12).
potent
antifungal
activity
(MICs = 15.63–
31.25 lg ⁄ mL) with respect to the reference drug
fluconazole against all tested yeasts. In addition,
the antileishmanial activity of title compounds was
determined against pormastigote form of Leish-
mania major. All compounds showed mild growth
inhibitory activity against promastigotes. The most
active compound was unsubstituted phenoxyace-
tophenone 2a (IC50 = 80 lg ⁄ mL). To anticipate the
With these issues in mind and for finding new bioactive compounds,
we replaced the methylene of propanone chain in dihydrochalcone
scaffold with oxygen to design phenoxyacetophenones (Figure 1).
Here, we report simple and convenient synthetic method for the
1

Ansari et al.
Figure 1: General structures of
chalcones, dihydrochalcones, and
designed compounds phenoxyace-
tophenone derivatives.
Figure 2: The atom numbering of compounds 2 and 3 for NMR
spectral data assignments.
synthesis of phenoxyacetophenones 2 and phenoxyacetophenones oxi-
mes 3 and evaluation of their antifungal and antileishmanial activities.
Experimental Section
Chemistry
All solvents and chemical reagents were purchased from Merck Co
(Darmstadt, Germany). and used without further purification. a-
Bromoacetophenone oxime 4 was prepared from a-bromoacetophe-
none 1 by using literature method (13). Melting points were deter-
mined in open glass capillaries using Bibby Stuart Scientific SMP3
apparatus (Stuart Scientific, Stone, UK) and are uncorrected. NMR
spectra were recorded using a Bruker 500 spectrometer (Bruker,
Rheinstetten, Germany), and chemical shifts are expressed as d
(ppm) with tetramethylsilane as internal standard. The atom num-
bering of compounds 2 and 3 for NMR spectral data assignments
was depicted in Figure 2. The IR spectra were obtained on a Per-
kin–Elmer FT-IR spectrophotometer (KBr disks). The progress of reac-
tions and the purity of the compounds were checked by thin-layer
chromatography (TLC) analysis on silica gel 60 F254 plates (Merck).
The visualization of spots on TLC was performed with UV light
(254 nm) or iodine. The synthetic route to phenoxyacetophenones 2
and their oximes 3 is presented in Scheme 1.
Scheme 1: Synthesis of compounds 2a–h and 3a–g.
Reagents and conditions: (a) K2CO3, DMF, rt; (b) hydroxylamine
hydrochloride, MeOH, rt.
added and the mixture was refrigerated overnight. The precipitated
solid was separated by filtration and washed with water
(3 · 20 mL) and dried to give pure compound 2.
2-Phenoxy-1-phenylethanone (2a)
Yellow solid; yield, 53%; m.p, 62–64 ꢀC; IR (KBr, per cm), 3438,
3064, 1708, 1599, 1499, 1433, 1249, 1227, 1174, 975. 1H NMR
3
(500 MHz, CDCl3) d: 5.27 (s, 2H, CH2O), 6.95 (d, 2H, J = 7.88 Hz,
3
H-2¢ and H-6¢ Ar), 6.99 (t, 1H, J = 7.38 Hz, H-4¢ Ar), 7.29 (t, 2H,
3
3J = 7.06 Hz, H-3¢ and H-5¢ Ar), 7.50 (t, 2H, J = 7.90 Hz, H-3 and
H-5 Ph), 7.62 (t, 1H, 3J = 7.42 Hz, H-4 Ph), 8.00 (d, 2H,
3J = 7.18 Hz, H-2 and H-6 Ph).
General procedure for the preparation of 2-
phenoxy-1-phenylethanones (2a–h)
A
suspension of appropriate phenol (6.18 mmol) and K2CO3
2-(3-Chlorophenoxy)-1-phenylethanone (2b)
White solid; yield, 91%; m.p, 91–93 ꢀC; IR (KBr, per cm), 1702,
1580, 1591, 1292, 1224, 1072, 977; 1H NMR (500 MHz, CDCl3) d:
(1.493 g, 10.8 mmol) in dry DMF (27 mL) was stirred at room tem-
perature for 10 min. Then, 2-bromoacetophenone (1.194 g, 6 mmol)
was added portionwise at room temperature and the stirring was
continued. After the completion of the reaction, water (25 mL) was
3
4
5.26 (s, 2H, CH2O), 6.83 (dd, 1H, J = 8.69 Hz, J = 2.5 Hz, H-6¢ Ar),
2
Chem Biol Drug Des 2012

2-Phenoxyacetophenones as Bioactive Compounds
6.93 (t, 1H, 4J = 2.17 Hz, H-2¢ Ar), 6.96 (dt, 1H, 3J = 7.91 Hz,
4J = 0.95 Hz, H-4¢ Ar), 7.19 (t, 1H, 3J = 8.14 Hz, H-5¢ Ar), 7.50 (t,
2H, 3J = 6.96 Hz, H-3 and H-5 Ph), 7.62 (tt, 1H, 3J = 7.46 Hz,
2-(3,4,5-Trimethoxyphenoxy)-1-phenylethanone
(2h)
White solid; yield, 65%; m.p, 102–104 ꢀC; IR (KBr, per cm), 2990,
1697, 1598, 1466, 1423, 1203, 1126, 1012. 1H NMR (500 MHz,
DMSO-d6) d: 3.58 (s, 3H, 4¢-OMe), 3.75 (s, 6H, 3¢-OMe and 5¢-
OMe), 5.53 (s, 2H, CH2O), 6.33 (s, 2H, H-2¢ and H-6¢ Ar), 7.57 (t, 2H,
3
4
4J = 1.19 Hz, H-4 Ph), 7.98 (dd, 2H, J = 8.25 Hz, J = 0.98 Hz, H-2
and H-6 Ph). 13C NMR (125 MHz, CDCl3) d: 70.73, 113.22, 115.35,
121.89, 128.09, 128.94, 130.32, 134.07, 134.36, 134.99, 158.71,
193.81.
3
3J = 7 Hz, H-3 and H-5 Ph), 7.69 (t, 1H, J = 7 Hz, H-4 Ph), 8.03 (d,
3
2H, J = 7 Hz, H-2 and H-6 Ph). 13C NMR (125 MHz, DMSO-d6) d:
55.87, 60.06, 70.45, 92.81, 127.85, 128.77, 131.88, 133.69, 134.50,
153.26, 154.45, 194.54. MS (m ⁄ z, %): 302 (M+, 97), 183 (41), 105
(100), 77 (49).
2-(3-Fluorophenoxy)-1-phenylethanone (2c)
White solid; yield, 66%; m.p, 82–84 ꢀC; IR (KBr, per cm), 1708,
1
1612, 1489, 1428, 1286, 1146, 983. H NMR (500 MHz, CDCl3) d:
5.26 (s, 2H, CH2O), 6.64–6.74 (m, 3H, H-2¢, H-4¢ and H-6¢ Ar), 7.19–
7.25 (m, 1H, H-5¢ Ar), 7.50 (t, 2H, 3J = 7.5 Hz, H-3 and H-5 Ph),
General procedure for the preparation of 2-
phenoxy-1-phenylethanone (Z)-oxime
derivatives [(Z)-3a-g]
3
3
7.62 (t, 1H, J = 7.4 Hz, H-4 Ph), 7.98 (d, 2H, J = 7.6 Hz, H-2 and
H-6 Ph).
To a solution of compound 2 (1 mmol,) in MeOH (4 mL), hydroxyl-
amine hydrochloride (277 mg, 4 mmol,) was added. The mixture
was stirred at room temperature for 2 days. After completing the
reaction, water (20 mL) was added and allowed to stay in refrigera-
tor overnight. The precipitated solid was separated by filtration and
washed with water (3 · 5 mL) and dried to give pure compound
(Z)-3.
2-(4-Fluorophenoxy)-1-phenylethanone (2d)
White solid; yield, 80%; m.p, 93–95 ꢀC; IR (KBr, per cm), 2925,
1
1689, 1507, 1450, 1219, 1084, 832. H NMR (500 MHz, CDCl3) d:
5.24 (s, 2H, CH2O), 6.86–6.90 (m, 2H, H-2¢ and H-6¢ Ar), 6.96 (t, 2H,
3
3J = 7.4 Hz, H-3¢ and H-5¢ Ar), 7.49 (t, 2H, J = 7.5 Hz, H-3 and H-5
3
3
Ph), 7.61 (t, 1H, J = 7.5 Hz, H-4 Ph), 7.97 (d, 2H, J = 7.4 Hz, H-2
and H-6 Ph). MS (m ⁄ z, %): 230 (M+, 45), 105 (100), 77 (77), 51 (20).
2-Phenoxy-1-phenylethanone oxime [(Z)-3a]
White solid; yield, 52%; m.p, 86–88 ꢀC; IR (KBr, per cm), 3790,
3435, 1600, 1498, 1459, 1308, 1263, 1213, 1049, 1086, 942. 1H
NMR (500 MHz, CDCl3) d: 5.29 (s, 2H, CH2O), 6.94 (d, 2H,
2-(2-Mehtoxyphenoxy)-1-phenylethanone (2e)
White solid; yield, 71%; m.p, 97–99 ꢀC; IR (KBr, per cm), 2920,
1
3
1687, 1507, 1470, 1255, 1211, 1130. H NMR (500 MHz, DMSO-d6)
3J = 7.93 Hz, H-2¢ and H-6¢ Ph), 6.96 (t, 1H, J = 7.34 Hz, H-4¢ Ph),
3
d: 3.78 (s, 3H, OCH3), 5.54 (s, 2H, CH2O), 6.80–7.05 (m, 4H, H-3¢,
H-4¢, H-5¢ and H-6¢ Ar), 7.47-7.64 (m, 2H, H-3 and H-5 Ph), 7.65–7.76
7.27 (t, 2H, J = 8.09 Hz, H-3¢ and H-5¢ Ph), 7.36–7.39 (m, 3H, H-3,
3
4
H-4 and H-5 Ph), 7.66 (dd, 2H, J = 7.82 Hz, J = 1.81 Hz, H-2 and
3
(m, 1H, H-4 Ph), 8.02 (d, 2 H, J = 6.7 Hz, H-2 and H-6 Ph). 13C NMR
H-6 Ph), 8.98 (br s, 1H, NOH).
(125 MHz, DMSO-d6) d: 55.51, 70.68, 112.42, 113.65, 120.49, 121.31,
127.84, 128.78, 133.71, 134.41, 147.38, 148.93, 194.68.
2-(3-Chlorophenoxy)-1-phenylethanone oxime
[(Z)-3b]
2-(3-Methoxyphenoxy)-1-phenylethanone (2f)
White solid; yield, 91%; m.p, 74–76 ꢀC; IR (KBr, per cm), 3445,
1644, 1596, 1477, 1296, 1054, 765. 1H NMR (500 MHz, CDCl3) d:
5.25 (s, 2H, CH2O), 6.8 (dd, 1H, 3J = 8.41, 4J = 1.7 Hz, H-6¢ Ar),
White solid; yield, 68%; m.p, 96–98 ꢀC; IR (KBr, per cm), 3002,
1
1697, 1582, 1499, 1193, 1158, 973. H NMR (500 MHz, DMSO-d6)
3
d: 3.73 (s, 3H, OCH3), 5.55 (s, 2H, CH2O), 6.48–6.60 (m, 3H, H-2¢,
H-4¢ and H-6¢ Ar), 7.17 (t, 1H, 3J = 7.7 Hz, H-5¢ Ar), 7.57 (t, 2H,
3J = 6.85 Hz, H-3 and H-5 Ph), 7.69 (t, 1H, 3J = 6.85 Hz, H-4 Ph),
8.03 (d, 2 H, 3J = 6.85 Hz, H-2 and H-6 Ph). 13C NMR (125 MHz,
DMSO-d6) d: 55.08, 70.09, 101.00, 106.48, 106.82, 127.84, 128.79,
129.86, 133.74, 134.38, 159.11, 160.41, 194.50.
6.91-6.95 (m, 2H, H-2¢ and H-4¢ Ar), 7.17 (t, 1H, J = 8.12 Hz, H-5¢
Ar), 7.34–7.38 (m, 3H, H-3, H-4 and H-5 Ph), 7.62 (dd, 2H,
4
3J = 7.01, J = 2.11 Hz, H-2 and H-6 Ph).
2-(3-Fluorophenoxy)-1-phenylethanone oxime
[(Z)-3c]
Light yellow; yield, 73%; m.p, 88–90 ꢀC, IR (KBr, per cm) 3236, 2938,
1608, 1596, 1489, 1292, 1265, 1138, 1051, 912. H NMR (500 MHz,
CDCl3) d: 5.25 (s, 2H, CH2O), 6.62–6.71 (m, 3H, H-2¢, H-4¢ and H-6¢ Ar),
7.15–7.21 (m, 1H, H-5¢ Ar), 7.33–7.43 (m, 3H, H-3, H-4 and H-5 Ph),
7.63 (dd, 2H, 3J = 7.94, 4J = 2.12 Hz, H-2 and H-6 Ph).
1
2-(4-Methoxyphenoxy)-1-phenylethanone (2g)
White solid; yield, 78%; m.p, 94–96 ꢀC; IR (KBr, per cm), 2833,
1691, 1507, 1448, 1216, 1187, 1029, 973. 1H NMR (500 MHz,
DMSO-d6) d: 3.69 (s, 3H, OCH3), 5.49 (s, 2H, CH2O), 6.85 (d, 2H,
3J = 8.3 Hz, H-3¢ and H-5¢ Ar), 6.91 (d, 2H, 3J = 8.1 Hz, H-2¢ and
H-6¢ Ar), 7.57 (t, 2H, 3J = 7.0 Hz, H-3 and H-5 Ph), 7.62–7.76 (m,
1H, H-4 Ph), 8.02 (d, 2H, 3J = 7.1 Hz, H-2 and H-6 Ph). 13C NMR
(125 MHz, DMSO-d6) d: 55.32, 70.64, 114.47, 115.49, 127.81,
128.78, 133.69, 134.44, 151.90, 153.55, 194.89. MS (m ⁄ z, %): 242
(M+, 100), 123 (46), 105 (99), 91 (32), 77 (94), 51 (22).
2-(4-Fluorophenoxy)-1-phenylethanone oxime
[(Z)-3d]
White solid; yield, 87%; m.p, 74–76 ꢀC; IR (KBr, per cm) 3251,
1
1595, 1474, 1506, 1310, 1219, 1029, 1011, 934. H NMR (500 MHz,
Chem Biol Drug Des 2012
3

Ansari et al.
CDCl3) d: 5.24 (s, 2H, CH2O), 6.83–6.87 (m, 2H, H-2¢ and H-6¢ Ar),
6.90–6.98 (m, 2H, H-3¢ and H-5¢ Ar), 7.32–7.45 (m, 3H, H-3 H-4,
and H-5 Ph), 7.59–7.63 (m, 2H, H-2 and H-6 Ph). MS (m ⁄ z, %): 245
(M+, 100), 230 (21), 125 (22), 103 (100), 91 (86), 77 (90).
Antifungal activity assay
The antifungal activity of phenoxyacetophenones 2 and oximes
derivatives 3 was evaluated against Candida albicans ATCC 10231,
Candida glabrata ATCC 90030, Saccharomyces cerevisiae NCYC 694,
S. cerevisiae ATCC 9763 and Aspergillus niger ATCC 16404. For all
fungi, the susceptibilities were determined by micro-dilution method
using 96 U-shaped wells plates (14). Briefly, twofold serial dilution
of the compounds was prepared by mixing 100 lL of stock solution
of each compounds (in DMSO) with Sabouraud dextrose broth
(100 lL) in ten wells. Then, aliquot of 100 lL of fungal suspension
(1 · 103 CFU ⁄ mL) was added to each well to reach the final inocu-
lum size of 0.5 · 103 CFU ⁄ mL. After incubation at 35 ꢀC, the plates
were tested for the absence or presence of visible growth in com-
parison with that of control well. The MIC value was defined as
lowest concentration of the compound at which there was no visi-
ble growth. The MIC values of test compounds were determined at
24 and 48 h for Candida and Saccharomyces strains, and 48 and
72 h for A. niger.
2-(2-Methoxyphenoxy)-1-phenylethanone oxime
[(Z)-3e]
White solid; yield, 81%; m.p, 90–92 ꢀC; IR (KBr, per cm) 3244,
1
2919, 1592, 1507, 1464, 1261, 1185, 1128, 743. H NMR (500 MHz,
DMSO-d6) d: 3.67 (s, 3H, OCH3), 5.20 (s, 2H, CH2O), 6.85–7.05 (m,
4H, Ar), 7.26–7.48 (m, 3H, H-3, H-4 and H-5 Ph), 7.64–7.72 (m, 2H,
H-2 and H-6 Ph), 11.85 (br s, 1H, NOH). 13C NMR (125 MHz,
DMSO-d6) d: 55.49, 59.31, 112.44, 113.38, 120.67, 121.48, 126.33,
128.21, 128.80, 134.37, 147.49, 149.08, 152.86.
2-(4-Methoxyphenoxy)-1-phenylethanone oxime
[(Z)-3f]
White solid; yield, 88%; m.p, 87–89 ꢀC; IR (KBr, per cm) 3379,
2950, 1625, 1450, 1510, 1236, 1210, 1044, 714. H NMR (500 MHz,
1
Antileishmanial activity assay
DMSO-d6) d: 3.67 (s, 3H, OCH3), 5.18 (s, 2H, CH2O), 6.83 (d, 2H,
3J = 8.1 Hz, H-3¢ and H-5¢ Ar), 6.85 (d, 2H, 3J = 8.1 Hz, H-2¢ and
H-6¢ Ar), 7.26–7.45 (m, 3H, H-3, H-4 and H-5 Ph), 7.55–7.78 (m, 2H,
H-2 and H-6 Ph), 11.85 (br s, 1H, NOH). MS (m ⁄ z, %): 257 (M+, 79),
123 (100), 109 (25), 95 (45), 77 (46).
The antipromastigote activity of compounds 2 and 3 was evaluated
by direct counting and MTT assay according to the literature
method (15). The percentage of inhibition of compounds against
promastigote form of Leishmania major (vaccine strain
MRHO ⁄ IR ⁄ 75 ⁄ ER, obtained from Pasteur institute, Tehran, Iran) was
determined at 75 lg ⁄ mL concentration. Briefly, promastigotes
(2 · 106 ⁄ mL) from early logarithmic phase of growth were cultured
in 96-well plastic plates, containing 75 lg ⁄ mL of compounds and
phenol red-free RPMI 1640 medium, supplemented with 10% of
FBS, 2 mM glutamine, pH ꢀ7.2, and antibiotics, in a volume of
200 lL. After 24 h of incubation at 25 ꢀC, the media was renewed
with 100 lg ⁄ well of MTT solution (0.5 mg ⁄ mL) and plates were fur-
ther incubated for 4 h at 37 ꢀC. The plates were centrifuged
(400 g, 5 min) and the pellets were dissolved in DMSO (200 lL).
The absorbance of sample was determined as the optical density at
492 nm in an ELISA plate reader. Two or more independent experi-
ments in triplicate were performed for each compound.
2-(3,4,5-Trimethoxyphenoxy)-1-phenylethanone
oxime [(Z)-3g]
Brown solid; yield, 64%; m.p, 106–108 ꢀC; IR (KBr, per cm) 3420,
2939, 1597, 1465, 1227, 1129, 1002, 945. 1H NMR (500 MHz,
DMSO-d6) d: 3.56 (s, 3H, 4¢-OMe) 3.72 (s, 6H, 3¢-OMe and 5¢-
OMe), 5.22 (s, 2H, CH2O), 6.28 (s, 2H, H-2¢ and H-6¢ Ar), 7.30–
7.46 (m, 3H, H-3, H-4 and H-5 Ph), 7.66 (m, 2H, H-2 and H-6 Ph),
11.97 (br s, 1H, NOH). MS (m ⁄ z, %): 317 (M+, 25), 302 (100), 287
(53), 183 (73), 168 (32), 151 (25), 119 (47), 105 (60), 91 (68), 77
(36).
The preparation of 2-phenoxy-1-phenylethanone
(E)-oxime [(E)-3a]
Results and Discussion
2-Bromoacetophenone oxime (4, 214 mg, 1.0 mmol) was added por-
tionwise to a suspension of phenol (97 mg, 1.03 mmol) and K2CO3
(248 mg, 1.8 mmol) in dry DMF (5 mL) at room temperature and
the reaction mixture was stirred for 3 days. After completing the
reaction, water (20 mL) was added and the precipitated solid was
separated by filtration. The crude product was mixed with %5
NaOH and extracted with CHCl3 (3 · 20 mL). The organic layer
was washed with water and dried (Na2SO4). The solvent was evap-
orated under reduced pressure to give pure product (E)-3a. White
solid; yield, 52%; m.p, 80–82 ꢀC; IR (KBr, per cm) 3696, 3385,
1594, 1487, 1443, 1284, 1251, 1112, 1018, 954. 1H NMR
Chemistry
The synthetic route to phenoxyacetophenones 2 and their oximes 3
is presented in Scheme 1. Phenoxyacetophenones 2 was prepared
by the reaction of a-bromoacetophenone 1 with appropriate phe-
nols in the presence of K2CO3 in dry DMF. Compounds 2 were pre-
dominantly converted to related (Z)-oximes
3 using excess
hydroxylamine hydrochloride in methanol. This reaction was carried
out at room temperature and mild acidic conditions provided by
hydrochloride salt of hydroxylamine. No refluxing or using a base-
like pyridine is required. The alternative route to oxime was
attempted by employing a-bromoacetophenone oxime 4. Thus,
a-bromoacetophenone 1 was firstly converted to a-bromoacetophe-
none oxime 4 in the presence of excess HONH2.HCl in methanol at
room temperature (13). a-Bromoacetophenone oxime 4 was reacted
with phenol in the presence of K2CO3 in dry DMF to give (E)-oxime
3a.
3
(500 MHz, CDCl3) d: 4.91 (s, 2H, CH2O), 6.94 (d, 2H, J = 8.56 Hz,
3
H-2¢ and H-6¢ Ph), 6.97 (t, 1H, J = 7.33 Hz, H-4¢ Ph), 7.27 (t, 2H,
3J = 7.64 Hz, H-3¢ and H-5¢ Ph), 7.40–7.45 (m, 3H, H-3, H-4 and
3
4
H-5 Ph), 7.61 (dd, 2H, J = 7.82 Hz, J = 1.39 Hz, H-2 and H-6 Ph),
8.29 (br s, 1H, NOH).
4
Chem Biol Drug Des 2012

2-Phenoxyacetophenones as Bioactive Compounds
1
The geometry of the oxime derivatives 3a-g was assigned by H
was equipotent to fluconazole with MIC values of 15.63–
NMR spectroscopy. The chemical shifts of the methylene protons
for the (E)- and (Z)-isomers of oxime derivatives 3a-g have signifi-
cant deviations. For example, compound (E)-3a showed a signal at
4.91 ppm, while (Z)-3a exhibited the corresponding signal at a
lower field, 5.29 ppm. Previous studies on oxime derivatives have
been established that proximity to the oxygen of the oxime in the
a-syn configuration will deshield the proton and cause a downfield
shift in the signals of related protons (16–20). Thus, the protons of
methylene that is syn to the oxime moiety shifted downfield in (Z)-
isomers.
31.25 lg ⁄ mL.
In general, oxime derivative 3d containing 4-fluorophenoxy moiety
showed good activity against all tested strain with the exception of
activity against A. niger. In fact, the results of antifungal evaluation
of test compounds indicated that compound 3d showed comparable
or more potent antifungal activity with respect to the reference
drug fluconazole against all tested yeasts. In contrast, ketone coun-
terpart of 3d (compound 2d) showed no inhibitory activity against
these fungi. Thus, it could be concluded that the oximation of 4-flu-
orophenoxyacetophenone improves antifungal activity. Moreover, by
comparing the activities of oximes 3a and 3d, it revealed that the
4-fluoro-substitution has a positive effect on antifungal potency.
Biological activity
The antifungal activity of compounds 2 and 3 was evaluated
against C. albicans, C. glabrata, S. cerevisiae, and A. niger. The
MIC values of compounds 2 and 3 were determined at 24 and
48 h for Candida and Saccharomyces strains, and 48 and 72 h for
A. niger by comparing with fluconazole as reference drug (Table 1).
The MIC values of the test compounds against C. albicans indicate
that oxime 3d possesses a remarkable activity with MIC values of
31.25 lg ⁄ mL. Its activity was 2–4 times more than the standard
drug fluconazole. Also, compounds 2a, 3b, and 3e showed weak
growth inhibition against C. albicans. Furthermore, compounds 3b
and 3d with MIC values of 15.63–31.25 lg ⁄ mL showed good activ-
ity against C. glabrata comparable or better than that of fluconaz-
ole. Although, compounds 2a, 2b, 2e, 2f, 2h, 3e, and 3e
exhibited some inhibitory activity against Saccharomyces strains,
but only the activity of compound 3d was respectable. Its activity
The antipromastigote activity of phenoxyacetophenones 2 and their
oximes 3 was evaluated against L. major. The percentage of inhibition
for each compound was expressed in mean values and presented in
Table 2. All compounds showed remarkable inhibition against prom-
astigotes in comparison with glucantime as a reference drug. The most
active compounds were unsubstituted phenoxyacetophenone 2a with
percentage of inhibition equal to 48% followed by 4-fluoro analog 2d
with 42 percent of inhibitory activity. A survey on the inhibitory activity
of test compounds against promastigotes revealed that substitution on
the different position of phenoxy moiety or oximation of ketone group
could not improve the antileishmanial activity. Also, by comparing the
inhibitory activity of (Z)- and (E)-stereoisomers of 3a, it could be con-
cluded that the geometry of oxime does not have a significant effect
on inhibitory activity against promastigotes.
Table 1: Minimum inhibitory concentrations (MICs, lg ⁄ mL) of synthetic compounds 2a–h and 3a–g against different strains of fungi
X
O
R
Aspergillus
Candida albicans
Candida glabrata
Saccharomyces
Saccharomyces
niger ATCC
ATCC 10231
ATCC 90030
cerevisiae NCYC 694
cerevisiae ATCC 9763
16404
Compound
X
R
24 h
48 h
24 h
48 h
24 h
48 h
24 h
48 h
48 h
72 h
2a
2b
O
O
O
O
O
O
O
O
NOH
NOH
NOH
NOH
NOH
NOH
NOH
H
3-Cl
3-F
4-F
2-OMe
3-OMe
4-OMe
3,4,5-(OMe)3
H
3-Cl
3-F
4-F
2-OMe
4-OMe
3,4,5-(OMe)3
125
>125
>125
>125
>125
>125
>125
>125
>125
125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
125
125
>125
>125
125
125
>125
125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
125
125
>125
>125
>125
>125
>125
>125
>125
>125
125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
–
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
>125
–
2c
2d
15.63
2e
>125
>125
>125
125
2f
2g
2h
(Z)-3a
(Z)-3b
(Z)-3c
(Z)-3d
(Z)-3e
(Z)-3f
(Z)-3g
Fluconazole
31.25
15.63
>125
31.25
31.25
>125
31.25
>125
>125
15.63
31.25
31.25
31.25
62.5
31.25
125
>125
>125
62.5
>125
>125
>125
125
>125
>125
>125
>125
>125
>125
125
125
>125
>125
>125
>125
125
125
125
>125
>125
125
31.25
62.5
15.63
31.25
15.63
31.25
The significance of bold values in comparison with control group was less than 0.05 (P < 0.05).
Chem Biol Drug Des 2012
5

Ansari et al.
Table 2: Antipromastigote activity of compounds 2a–h and 3a–
like' based on the structural properties that affect the physicochem-
ical properties of solubility and permeability and their effect on
drug absorption.
f
X
O
To anticipate the potential use as drugs, the compounds described
here are evaluated in their drug-like properties – for example,
mutagenicity, tumorigenicity, irritating and reproductive effects,
cLogP (calculated n-octanol ⁄ water partition coefficient), LogS (solu-
bility), and MW (molecular weight) – using in silico approaches pro-
vided by Osiris Properties Explorer toolsa (Table 3). Also, from this
online properties explorer, the descriptors' drug-likeness and drug
score were estimated for target compounds. According to these
predictive tools, bioactive compounds 2a and 3d are supposed to
be non-mutagenic and non-tumorigenic, with no irritating or repro-
ductive effects (Table 3). Moreover, compound 2a showed satisfac-
tory drug-likeness and drug score, according to the classification of
the Osiris Properties Explorer tools.
R
Compounds
X
R
% Inhibition (75 lg ⁄ mL)
2a
2b
O
O
O
O
O
O
O
O
NOH
NOH
NOH
NOH
NOH
NOH
NOH
H
3-Cl
3-F
4-F
48a
22
38
42
34
30
30
33
37
33
27
35
37
30
20
50b
2c
2d
2e
2-OMe
3-OMe
4-OMe
3,4,5-(OMe)3
H
2f
2g
2h
(E)-3a
(Z)-3a
(Z)-3b
(Z)-3c
(Z)-3d
(Z)-3e
(Z)-3f
Glucantime
H
3-Cl
3-F
4-F
On the other hand, a set of simple molecular descriptors including
logP, molecular weight (MW), number of hydrogen bond acceptors
(HBA), and number of hydrogen bond donors (HBD) were used by
Lipinski in formulating his 'Rule of 5'. Accordingly, the 'Rule of 5'
defines four simple physicochemical parameter ranges (MW £ 500,
Log P £ 5, HBD £ 5, HBA £ 10) for oral absorption (22). Molecules
violating more than one of these rules may have problems with bio-
availability. The values of molecular descriptors for bioactive com-
pounds 2a and 3d reveal that these compounds are within the
range set by Lipinski's 'Rule of 5' (low molecular weight, favorable
cLogP, favorable hydrogen bond-donating and accepting capabilities)
and show no violation of these rules.
2-OMe
4-OMe
aThe IC50 value of compound 2a was 80 lg ⁄ mL.
bGlucantime was tested at the dose of 25 mg ⁄ mL.
In silico study
Toxicity studies were traditionally conducted during the drug devel-
opment; however, it has been a major cause of drug candidate
attrition during preclinical and clinical phases. Thus, the early
knowledge about the toxicity of lead compounds allows us to suc-
cessful achieving to the drugs (21). On the other hand, appropriate
drug-like properties of lead compounds also allow us to convert
them into successful drugs. Lipinski (22) introduced the term 'drug-
Conclusion
In summary, to find new bioactive compounds, we designed a ser-
ies of phenoxyacetophenone derivatives 2 and their related oximes
Table 3: Predicted toxicity risks and drug-like properties estimated by Osiris Property Explorer tools
Toxicity risksa
Drug-like properties
Compound
M
T
I
R
cLogP
LogS
MW
Drug-likeness
Drug score
2a
2b
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
())
(€)
())
())
())
())
())
())
())
())
())
())
())
(€)
())
())
(+)
())
())
())
())
(€)
())
())
())
())
2.84
3.45
2.9
)3.25
)3.99
)3.56
)3.56
)3.27
)3.27
)3.27
)3.3
)3.62
)4.36
)3.94
)3.94
)3.64
)3.64
)3.68
212
246
230
230
242
242
242
302
227
261
245
245
257
257
317
0.89
0.22
)2.45
)0.34
1.51
0.09
0.88
2.4
0.06
)0.35
)3.04
)0.87
1.02
0.36
1.92
0.74
0.6
2c
2d
0.36
0.59
0.78
0.32
0.74
0.81
0.63
0.51
0.33
0.51
0.71
0.65
0.76
2.9
2e
2.73
2.73
2.73
2.52
3.07
3.69
3.13
3.13
2.97
2.97
2.76
2f
2g
2h
(Z)-3a
(Z)-3b
(Z)-3c
(Z)-3d
(Z)-3e
(Z)-3f
(Z)-3g
aRanked according to: ()) no bad effect, (€) medium bad effect, (+) bad effect.
M, mutagenic effect; T, tumorigenic effect; I, irritating effect; R, reproductive effect.
6
Chem Biol Drug Des 2012

2-Phenoxyacetophenones as Bioactive Compounds
3 as analogs of dihydrochalcones. The in vitro antifungal evaluation
of target compounds revealed the oxime derivative 3d containing
4-fluorophenoxy moiety possessing comparable or more potent anti-
fungal activity with respect to the reference drug fluconazole
against all tested yeasts. Moreover, all compounds showed remark-
able growth inhibitory activity against promastigotes of L. major in
MTT assay. The most active compound was unsubstituted phenoxy-
acetophenone 2a. In silico molecular properties calculations and
SAR study confirmed that compounds 2a and 3d are promising
lead compounds for further development without great risk of toxic-
ity in diverse fields of antileishmanial and antifungal activities.
9. Narender T., Shweta, Gupta S. (2004) A convenient and bioge-
netic type synthesis of few naturally occurring chromenodihydr-
ochalcones and their in vitro antileishmanial activity. Bioorg
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10. Kayser O., Kiderlen A.F., Folkens U., Kolodziej H. (1998) Antile-
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This work was supported by a grant from the Research Council of
Mazandaran University of Medical Sciences, Sari, Iran.
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