Synthesis of novel coumarin substituted amide derivatives and their antibacterial activities

Article abstract of DOI:10.1007/s11696-017-0149-0

A series of novel coumarin substituted amide derivatives were synthesized and evaluated for their antibacterial activities. Result indicated that compounds 3f, 3g, 3h, 3i, 3j, 3k, 3l, 3m, 3n, 3o and 3q exhibited excellent antibacterial activities against

Full text of DOI:10.1007/s11696-017-0149-0

Chem. Pap.
DOI 10.1007/s11696-017-0149-0
ORIGINAL PAPER
Synthesis of novel coumarin substituted amide derivatives
and their antibacterial activities
Mei-Hang Chen1
Dao-Wang Lu1 Xun Zhang1 Zeng-Yan Zhou1
•
•
•
•
Xiao-Bin Wang2 Hua Shu1
•
Received: 1 July 2016 / Accepted: 17 February 2017
Ó Institute of Chemistry, Slovak Academy of Sciences 2017
Abstract A series of novel coumarin substituted amide
derivatives were synthesized and evaluated for their
antibacterial activities. Result indicated that compounds 3f,
3g, 3h, 3i, 3j, 3k, 3l, 3m, 3n, 3o and 3q exhibited excellent
antibacterial activities against Xanthomonas oryzae pv.
oryzae (Xoo) and Xanthomonas citri subsp. Citri (Xcc)
in vitro, which were better than those of commercial agri-
cultural antibacterial thiodiazole-copper. The title com-
pounds with electron-withdrawing group showed better
antibacterial activities than those of compounds with elec-
tron-donating group, and the title compounds bearing the
same substituent group exhibited better antibacterial activi-
ties against Xcc than antibacterial activities against Xoo.
species (Rudolph 1993). Among them, Xanthomonas ory-
zae pv. oryzae (Xoo) and Xanthomonas citri subsp. Citri
(Xcc) are two kinds of important Xanthomonas species
(Young et al. 2010). To date, some of traditional bacteri-
cides (thiodiazole-copper, Streptomycin and Kocide) and
control methods are insufficient to manage the diseases
caused by Xoo or Xcc (Boch and Bonas 2010; Evidente
et al. 2011; Xu et al. 2015). Therefore, development of
novel antibacterial agents remains a daunting task in pes-
ticide science.
Coumarin, a class of benzopyrone derivatives, widely
distributes in the plants and exhibit extensive pharmaco-
logical activities, such as anticoagulants (Pasciak et al.
2014), anticancer (Belluti et al. 2010; Sashidhara et al.
2010; Chen et al. 2013; Zhang et al. 2014; Rajabi et al.
2015), antioxidant (Zhang et al. 2011), anti-HIV (Olomola
et al. 2013), antimalarial (Sashidhara et al. 2012; Pingaew
et al. 2014), anti-depressant-like (Sashidhara et al. 2015),
and antimicrobial (Arshad et al. 2011) activities. Previous
studies found coumarin-6-sulfonamides with a free C4-
azidomethyl group and were used as potential antimicro-
bials (Basanagouda et al. 2010). Recent studies demon-
strated that novel iodinated-4-aryloxymethylcoumarins
derivatives exhibited antimycobacterial activities (Basa-
nagouda et al. 2014). In our previous works, a series of
Keywords Coumarin Á Amide derivatives Á Synthesis Á
Antibacterial activity
Introduction
Xanthomonas, a genus of proteobacteria, caused a number
of plant diseases and gave rise to bacterial spots and blights
of leaves, stems, and fruits on a wide variety of plant
Mei-Hang Chen and Dao-Wang Lu have contributed equally to this
work.
novel
(E)-4-(4-((arylidene)amino)phenoxy
coumarin
derivatives were synthesized and found that most of them
exhibited pronounced antibacterial activities against Xoo or
Xcc. (Chen et al. 2016).
& Mei-Hang Chen
chenmeihang0123@126.com
1
School of Material and Chemistry Engineering, Tongren
University, Bijiang District, Tongren 554300, China
Amides are important classes of nitrogen organic com-
pounds because of having extensive biological activities,
such as anticancer (Lu et al. 2010; Pradidphol et al. 2012;
Li et al. 2014; Yang et al. 2015), antibacterial (Stefanska
et al. 2015), antifungal (Wang, et al. 2014), anticonvulsant
(Tripath et al. 2012), antiviral (Huang et al. 2015), and
2
State Key Laboratory Breeding Base of Green Pesticide and
Agricultural Bioengineering, Key Laboratory of Green
Pesticide and Agricultural Bioengineering, Ministry of
Education, Guizhou University, Huaxi District,
Guiyang 550025, China
123

Chem. Pap.
Scheme.1 Synthetic route of the title compounds (3a–3q)
General procedure for preparation of 4-
chlorocoumarin (1)
antimalarial (Smit and N’Da 2014) activities. A large
amount of studies devoted to the aromatic amide deriva-
tives as potential antibacterial and antifungal agents; some
of them were used in the agricultural production (Zhang
2007). Our research group is interested in aromatic amide
derivatives and synthesized a serial of novel amide
derivatives containing a triazole moiety with antibacterial
properties against plant fungi and bacteria (Tang et al.
2013).
4-chlorocoumarin (1) was synthesized by following the
procedures described in the literature (Rao and Kumar
2014).
General procedure for preparation of 4-(4-
aminophenoxy)coumarin (2)
Based on the above findings, we speculated that an
attempt was made to incorporate amides structural unit on
the backbone of coumarin might to produce a new active
molecules of antibacterial activity. Herein, a series of novel
coumarin substituted amide derivatives were designed,
synthesized (Scheme.1), and evaluated their antibacterial
activities against Xoo and Xcc in vitro.
A mixture of compound 1 (0.1 mol), 4-aminophenol
(0.1 mol), and K2CO3 (0.12 mol) was dissolved in CH3CN
(300 mL) and refluxing. After refluxing for 4 h, the reac-
tion solution was poured into 1000 mL of water to produce
a solid precipitates and filtered. Compound 2 was recrys-
tallized from ethanol. The properties and analytical data for
compound 2 are listed in Table 1, and the spectral data are
shown in Table 2.
Experimental
General procedure for preparation of title
compounds (3a–3q)1
The course of the reactions was monitored by thin-layer
chromatography (TLC) performed on silica gel GF 254
(Merck, Germany). Unless stated otherwise, all reagents
were of analytical grade or chemically pure and pur-
chased from Heowns Biochem Technologies (China)
and Aladdin Chemical (China). All anhydrous solvents
were dried and purified in accordance with the standard
A mixture of compound 2 (1.0 mmol), aromatic acid
(1.0 mmol), and 4-dimethylaminopyridine (0.1 mmol) was
dissolved in CH2Cl2 (150 mL) and stirred at room tem-
perature. After stirring for 0.5 h, 1-(3-dimethylamino-
propyl)-3-ethylcarbodi- imide hydrochloride (1.2 mmol)
was added. The resulting mixture was stirred at room
temperature for 1–2 h. The solvent was removed under
vacuum when the reaction was complete and the residue
was recrystallized from ethanol to obtain novel amide
derivatives containing coumarin (3a–3q). The properties,
analytical and spectral data of the title compounds are
listed in Table 1 and Table 2.
1
techniques immediately prior to use. H NMR and 13C
NMR spectral analyses were performed on a JEOL-
ECX 500 NMR spectrometer (Japan) at ambient tem-
perature using DMSO-d6 as solvents. TMS as an
internal standard and chemical shift is given in d rel-
ative to TMS. IR spectra were recorded on a Bruker
VECTOR 22 (Germany) spectrometer using a KBr disk
technique. Elemental analysis was performed on an
Elementar Vario-III CHN analyser (Elementar, Ger-
man). Melting points of the title compounds were
determined on an XT-4 binocular microscope (Beijing
Tech Instrument, China).
1
All of new compounds were named with IUPAC name
123

Chem. Pap.
Table 1 Physical properties
and analytical data of
compounds (2, 3a–3q)
Compound Formula
Mwt
Appearance Yield (%)a M.p (°C)a wi (calc.) (%)
wi (found) (%)
C
H
N
2
C15H11NO3
253.25 Brown solid 83
163–165
141–143
–
–
–
3a
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
22H15NO4
23H17NO4
23H17NO5
23H17NO5
25H21NO4
22H14FNO4
22H14ClNO4
357.36 White solid
371.39 White solid
387.38 White solid
387.38 White solid
399.44 White solid
375.35 White solid
391.80 White solid
71
63
79
60
55
74
67
62
70
59
68
71
66
67
75
80
72
73.94
74.01
74.38
74.41
71.31
71.37
71.31
4.23
4.20
4.61
4.60
4.42
4.39
4.42
3.92
3.85
3.77
3.75
3.62
3.57
3.62
3b
3c
3d
3e
3f
147–149
153–155
157–159
146–148
151–153
159–162
177–179
193–195
197–199
188–190
180–183
176–178
180–183
160–163
169–172
169–172
71. 29 4. 45 3.67
75.17
75.22
70.40
70.47
67.44
67.41
61.99
61.89
60.57
60.72
60.57
60.60
65.67
65.49
65.67
65.55
62.59
62.52
62.59
62.67
70.40
70.57
74.38
74.33
64.94
65.02
5.30
5.24
3.76
3.69
3.60
3.64
3.07
3.15
3.23
3.19
3.23
3.13
3.51
3.60
3.51
3.63
3.20
3.30
3.20
3.13
3.76
3.63
4.61
4.50
3.32
3.19
3.51
3.45
3.75
3.79
3.57
3.71
3.29
3.35
3.21
3.09
3.21
3.05
6.96
6.78
6.96
6.80
3.17
3.09
3.17
3.02
3.75
3.63
3.77
3.69
3.29
3.18
3g
3h
3i
22H13Cl2NO4 426.25 White solid
22H14BrNO4
22H14BrNO4
22H14N2O6
22H14N2O6
23H14F3NO5
23H14F3NO5
22H14FNO4
23H17NO4
436.25 White solid
436.25 White solid
402.36 White solid
402.36 White solid
441.36 White solid
441.36 White solid
375.35 White solid
371.39 White solid
3j
3k
3l
3m
3n
3o
3p
3q
a
23H14 F3NO5 425.36 White solid
Recrystallized from ethanol
Antibacterial biological assay
the non-toxic nutrient broth (NB: 1.5 g of beef extract,
2.5 g of peptone, 0.5 g of yeast powder, 5.0 g of glucose
and 500 mL of distilled water, pH 7.0–7.2) liquid medium
in 4 mL tubes. Then, 40 lL of NB containing Xoo was
added to 5 mL of solvent NB containing the test com-
pounds or thiodiazole-copper. The inoculated test tubes
were incubated at (30 1) °C under continuous shaking
at 180 min-1 for 48 h. The culture growth was monitored
spectrophotometrically by measuring the optical density at
600 nm (OD600) and expressed as corrected turbidity. The
The title compounds (3a-3q) evaluated antibacterial
activities against Xoo and Xcc in vitro using the tur-
bidimeter test (Xu et al. 2012; Wang et al. 2013). Com-
mercial agricultural antibacterial thiodiazole-copper was
used as control. The test compounds were dissolved in
150 lL of dimethylformamide and diluted with Tween-20
(0.1 vol.%) to prepare two concentrations of 200 and 100
(all in lg mL-1). 1 mL of the liquid sample was added to
123

Chem. Pap.
Table 2 Spectral data of compounds (2, 3a–3p)
Compound Spectral data
2
1H NMR (500 MHz, DMSO-d6) d: 8.17 (1H, d, J = 7.0 Hz, coumarin-5-H), 7.60 (1H, t, J = 5.0 Hz, coumarin-7-H), 7.34–7.30
(2H, m, coumarin-6,8-H); 6.95 (2H, d, J = 8.5 Hz, Ar–H), 6.62 (2H, d, J = 8.5 Hz, Ar–H), 5.22 (2H, s, NH2), 4.95 (1H, s,
coumarin-3-H)
13C NMR (125 MHz, DMSO-d6) d: 166.37, 161.83, 153.64, 151.52, 133.86, 131.13, 125.04, 123.49, 117.14, 112.72, 107.86,
106.08, 93.06
3a
IR (KBr, cm-1) m: 3341, 1704, 1624, 1606, 1565, 1189
1H NMR (500 MHz, DMSO-d6) d: 10.52 (1H, s, CON-H), 8.08 (1H, J = 8.0 Hz, coumarin-5-H), 7.99 (2H, d, J = 7.5 Hz, Ar–H),
7.91–7.75 (2H, m, Ar–H), 7.63–7.46 (6H, m, coumarin-6,7,8-H, Ar–H), 7.13 (2H, d, J = 8.0 Hz, Ar–H), 5.31 (1H, s, coumarin-3-
H)
13C NMR (125 MHz, DMSO-d6) d: 166.39, 166.15, 161.67, 153.64, 152.59, 141.62, 135.10, 133.97, 132.34, 131.12, 128.97,
128.22, 125.09, 123.52, 118.83, 117.16, 116.64, 115.25, 113.19, 93.49
3b
3c
3d
3e
3f
IR (KBr, cm-1) m: 3345, 1716, 1627, 1604, 1567, 1185
1H NMR (500 MHz, DMSO-d6) d: 10.52 (1H, s, CON-H), 8.36 (2H, J = 8.0 Hz, Ar–H), 8.06–7.95 (2H, m, coumarin-5-H, Ar–H),
7.83–7.79 (2H, m, Ar–H), 7.59–7.48 (4H, m, coumarin-6,7,8-H, Ar–H), 7.30 (2H, d, J = 7.5 Hz, Ar–H), 5.38 (1H, s, coumarin-3-
H), 2.36 (3H, s, CH3)
13C NMR (125 MHz, DMSO-d6) d: 166.39, 166.15, 161.67, 153.64, 152.59, 141.62, 135.10, 133.97, 132.34, 131.12, 128.97,
128.22, 125.09, 123.52, 118.83, 117.16, 116.64, 115.25, 113.19, 93.49, 22.14
IR (KBr, cm-1) m: 3349, 1717, 1627, 1607, 1558, 1186
1H NMR (500 MHz, DMSO-d6) d: 10.41 (1H, s, CON-H), 8.07 (1H, d, J = 8.0 Hz, coumarin-5-H), 7.88 (1H, d, J = 8.0 Hz, Ar–
H), 7.78–7.62 (4H, m, coumarin-6,7,8-H, Ar–H), 7.54–7.46 (4H, m, Ar–H), 7.11–7.06 (2H, m, Ar–H), 5.29 (1H, s, coumarin-3-
H), 3.90 (3H, s, OCH3)
13C NMR (125 MHz, DMSO-d6) d: 166.19, 165.49, 161.69, 156.98, 153.65, 152.70, 141.51, 133.97, 132.75, 131.20, 130.14,
125.09, 123.54, 121.02, 117.16, 116.52, 115.34, 112.62, 112.51, 93.49, 56.40
IR (KBr, cm-1) m: 3369, 1714, 1623, 1607, 1565, 1176
1H NMR (500 MHz, DMSO-d6) d: 10.37 (1H, s, CON-H), 8.07 (1H, J = 8.0 Hz, coumarin-5-H), 7.98 (2H, d, J = 9.0 Hz, Ar–H),
7.90 (1H, d, J = 7.5 Hz, Ar–H), 7.78–7.74 (2H, m, Ar–H), 7.55–7.46 (3H, m, coumarin-6,7,8-H), 7.10–7.07 (3H, m, Ar–H), 5.31
(1H, s, coumarin-3-H), 3.84 (3H, s, OCH3)
13C NMR (125 MHz, DMSO-d6) d: 166.19, 165.72, 162.62, 161.70, 153.67, 152.60, 141.86, 133.98, 131.06, 130.23, 127.06,
125.11, 123.54, 117.18, 116.37, 114.21, 113.17, 93.50, 55.99
IR (KBr, cm-1) m: 3341, 1704, 1624, 1606, 1565, 1201
1H NMR (500 MHz, DMSO-d6) d: 10.50 (1H, s, CON-H), 8.31 (2H, J = 8.0 Hz, Ar–H), 8.07 (1H, d, J = 8.0 Hz, coumarin-5-H),
7.90 (1H, d, J = 7.5 Hz, Ar–H), 7.76–7.51 (6H, m, coumarin-6,7,8-H, Ar–H), 7.39 (2H, d, J = 9.0 Hz, Ar–H), 5.35 (1H, s,
coumarin-3-H), 2.21–2.19 (1H, m, CH), 1.23 (6H, s, 2CH3)
13C NMR (125 MHz, DMSO-d6) d: 166.19, 165.90, 162.62, 161.73, 153.67, 152.67, 141.68, 133.57, 132.30, 131.20, 130.14,
125.09, 124.54, 121.02, 118.76,117.57, 115.80, 114.91, 113.19, 93.50, 33.20, 24.02
IR (KBr, cm-1) m: 3289, 1723, 1623, 1609, 1566, 1195
1H NMR (500 MHz, DMSO-d6) d: 10.56 (1H, s, CON-H), 8.07 (1H, J = 8.0 Hz, coumarin-5-H), 8.03 (1H, d, J = 8.0 Hz, Ar–H),
7.96–7.93 (3H, m, Ar–H), 7.78–7.45 (5H, m, coumarin-6,7,8-H, Ar–H), 7.36 (2H, d, J = 8.5 Hz, Ar–H), 5.24 (1H, s, coumarin-3-
H)
13C NMR (125 MHz, DMSO-d6) d: 166.55, 164.76, 161.70, 153.643, 148.24, 138.13, 137.34, 133.97, 133.76, 132.04, 131.01,
127.98, 127.08, 125.08, 123.57, 122.09, 117.16, 115.31, 113.19, 93.30
3g
3h
IR (KBr, cm-1) m: 3289, 1723, 1623, 1609, 1566, 1195
1H NMR (500 MHz, DMSO-d6) d: 10.56 (1H, s, CON-H), 8.07 (1H, J = 8.0 Hz, coumarin-5-H), 8.03 (1H, d, J = 8.0 Hz, Ar–H),
7.96–7.93 (3H, m, Ar–H), 7.78–7.45 (5H, m, coumarin-6,7,8-H, Ar–H); 7.39 (2H, d, J = 8.5 Hz, Ar–H), 5.24 (1H, s, coumarin-3-
H)
13C NMR (125 MHz, DMSO-d6) d: 166.55, 164.76, 161.70, 153.643, 148.24, 138.13, 137.34, 133.97, 133.76, 132.04, 131.01,
127.98, 127.08, 125.08, 123.57, 122.09, 117.16, 115.31, 113.19, 93.30
IR (KBr, cm-1) m: 3301, 1700, 1621, 1605, 1564, 1191
1H NMR (500 MHz, DMSO-d6) d: 10.52 (1H, s, CON-H), 8.05 (2H, J = 8.5 Hz, coumarin-5-H), 8.01 (1H, d, J = 8.0 Hz, Ar–H),
7.95–7.91 (2H, m, Ar–H), 7.82–7.47 (4H, m, coumarin-6,7,8-H, Ar–H), 7.38 (2H, d, J = 8.0 Hz, Ar–H), 5.29 (1H, s, coumarin-3-
H)
13C NMR (125 MHz, DMSO-d6) d: 166.15, 164.87, 161.67, 153.66, 152.72, 141.16, 135.87, 135.62, 133.99, 131.78, 131.40,
130.96, 128.05, 125.10, 123.54, 118.26, 117.17.03, 117.10, 115.26, 112.59, 93.53
123

Chem. Pap.
Table 2 continued
Compound Spectral data
3i
IR (KBr, cm-1) m: 3359, 1717, 1623, 1606, 1564, 1173
1H NMR (500 MHz, DMSO-d6) d: 10.91 (1H, s, CON-H), 8.07 (1H, J = 8.0 Hz, coumarin-5-H), 7.84–7.75 (3H, m, Ar–H), 7.69
(1H, J = 8.0 Hz, Ar–H), 7.63–7.46 (5H, m, coumarin-6,7,8-H, Ar–H), 7.39 (2H, d, J = 8.5 Hz, Ar–H), 5.29 (1H, s, coumarin-3-
H)
13C NMR (125 MHz, DMSO-d6) d: 166.67, 165.15, 161.82, 153.65, 152.71, 151.51, 141.35, 139.25, 133.83, 133.30, 131.35,
129.45, 128.30, 125.07, 125.01, 123.52, 117.14, 116.92, 112.51, 107.86, 93.49
3j
3k
3l
IR (KBr, cm-1) m: 3382, 1699, 1622, 1609, 1564, 1192
1H NMR (500 MHz, DMSO-d6) d: 10.59 (1H, s, CON-H), 8.07 (1H, J = 8.0 Hz, coumarin-5-H), 7.93–7.89 (2H, m, Ar–H),
7.78–7.73 (3H, m, Ar–H), 7.57–7.46 (4H, m, coumarin-6,7,8-H, Ar–H), 7.14 (2H, d, J = 8.0 Hz, Ar–H), 5.30 (1H, s, coumarin-3-
H)
13C NMR (125 MHz, DMSO-d6) d: 166.16, 165.40, 161.68, 153.66, 152.62, 141.44, 134.15, 133.99, 132.01, 130.39, 126.18,
125.11, 123.54, 118.93, 116.85, 115.21, 113.32, 93.52
IR (KBr, cm-1) m: 3364, 1696, 1623, 16011, 1558, 1193
1H NMR (500 MHz, DMSO-d6) d: 10.99 (1H, s, CON-H), 8.19 (1H, J = 8.0 Hz, Ar–H), 8.07 (1H, d, J = 7.0 Hz, coumarin-5-H),
7.91–7.75 (5H, m, Ar–H), 7.58–7.46 (4H, m, coumarin-6,7,8-H, Ar–H); 7.17 (1H, d, J = 8.5 Hz, Ar–H), 5.31 (1H, s, coumarin-3-
H)
13C NMR (125 MHz, DMSO-d6) d: 166.12, 164.99, 161.67, 153.67, 152.76, 146.90, 141.23, 141.23, 134.76, 133.98, 131.75,
131.43, 129.86, 125.09, 124.89, 123.55, 118.26, 117.16, 117.07, 112.60, 93.52
IR (KBr, cm-1) m: 3325, 1701, 1623, 1610, 1564, 1192
1H NMR (500 MHz, DMSO-d6) d: 10.85 (1H, s, CON-H), 8.39 (2H, J = 8.0 Hz, Ar–H), 8.21 (2H, J = 8.0 Hz, Ar–H), 8.07 (1H,
d, J = 7.5 Hz, coumarin-5-H), 7.90–7.75 (2H, m, Ar–H), 7.59–7.48 (3H, m, coumarin-6,7,8-H), 7.17 (2H, d, J = 7.0 Hz, Ar–H),
5.31 (1H, s, coumarin-3-H)
13C NMR (125 MHz, DMSO-d6) d: 166.15, 164.76, 161.68, 153.66, 152.64, 149.79, 141.16, 140.74, 134.00, 131.28, 129.83,
125.11, 124.14, 123.54, 119.03, 117.18, 115.26, 113.44, 93.55
3m
3n
IR (KBr, cm-1) m: 3350, 1695, 1623, 1606, 1563, 1188
1H NMR (500 MHz, DMSO-d6) d: 10.49 (1H, s, CON-H), 8.07 (1H, d, J = 8.0 Hz, coumarin-5-H), 7.95 (2H, d, J = 8.0 Hz, Ar–
H), 7.86–7.74 (4H, m, Ar–H), 7.53–7.46 (3H, m, coumarin-6,7,8-H), 7.36 (2H, d, J = 8.5 Hz, Ar–H), 5.37 (1H, s, coumarin-3-H)
13C NMR (125 MHz, DMSO-d6) d: 166.36, 166.82, 161.69, 153.63, 155.55, 15271, 151.52, 14130, 133.84, 131.37, 131.13, 128.12,
125.01, 123.48, 118.24, 117.12, 117.01, 115.37, 112.73, 93.05
IR (KBr, cm-1) m: 3375, 1696, 1623, 1609, 1564, 1192
1H NMR (500 MHz, DMSO-d6) d: 10.59 (1H, s, CON-H), 8.07 (1H, J = 7.0 Hz, coumarin-5-H), 8.00 (2H, d, J = 8.0 Hz, Ar–H),
7.89 (1H, s, Ar–H), 7.78–7.73 (2H, m, Ar–H), 7.64–7.46 (5H, m, coumarin-6,7,8-H, Ar–H), 7.14 (2H, d, J = 8.0 Hz, Ar–H), 5.30
(1H, s, coumarin-3-H)
13C NMR (125 MHz, DMSO-d6) d: 166.16, 165.28, 161.69, 153.66, 152.62, 141.45, 137.20, 134.00, 133.79, 131.18, 130.23,
129.09, 125.12, 123.54, 118.93, 117.18, 116.85, 115.27, 113.32, 93.53
3o
3p
3q
IR (KBr, cm-1) m: 3351, 1709, 1625, 1604, 1564, 1188
1H NMR (500 MHz, DMSO-d6) d: 10.56 (1H, s, CON-H), 8.07 (1H, J = 8.0 Hz, coumarin-5-H), 7.96–7.93 (2H, m, Ar–H),
7.79–7.75 (3H, m, Ar–H), 7.63–7.52 (4H, m, coumarin-6,7,8-H, Ar–H), 7.17 (2H, d, J = 8.0 Hz, Ar–H), 5.33 (1H, s, coumarin-3-
H)
13C NMR (125 MHz, DMSO-d6) d: 166.39, 166.15, 161.67, 153.64, 152.59, 141.62, 135.10, 133.97, 132.34, 131.12, 128.97,
128.22, 125.09, 123.52, 118.83, 117.16, 116.64, 115.25, 113.19, 93.49
IR (KBr, cm-1) m: 3352, 1706, 1621, 1604, 1564, 1189
1H NMR (500 MHz, DMSO-d6) d: 10.51 (1H, s, CON-H), 8.07 (1H, J = 8.0 Hz, coumarin-5-H), 7.95 (2H, d, J = 7.5 Hz, Ar–H),
7.83–7.75 (4H, m, Ar–H), 7.59–7.43 (3H, m, coumarin-6,7,8-H, Ar–H), 7.39 (2H, d, J = 8.5 Hz, Ar–H), 5.35 (1H, s, coumarin-3-
H), 2.25 (3H, s, CH3)
13C NMR (125 MHz, DMSO-d6) d: 166.51, 166.15, 161.87, 154.01, 152.51, 141.69, 135.17, 133.99, 132.51, 132.01, 128.98,
128.24, 125.34, 122.84, 119.12, 117.18, 116.64, 115.25, 112.99, 93.52, 22.13
IR (KBr, cm-1) m: 3351, 1708, 1625, 1605, 1564, 1187
1H NMR (500 MHz, DMSO-d6) d: 10.52 (1H, s, CON-H), 8.07 (1H, d, J = 8.0 Hz, coumarin-5-H), 7.95 (1H, d, J = 7.5 Hz, Ar–
H), 7.83–7.75 (4H, m, Ar–H), 7.59–7.43 (4H, m, coumarin-6,7,8-H, Ar–H), 7.39 (2H, d, J = 8.0 Hz, Ar–H), 5.32 (1H, s,
coumarin-3-H)
13C NMR (125 MHz, DMSO-d6) d: 166.39, 166.15, 161.67, 153.64, 152.59, 141.62, 135.10, 133.97, 132.34, 131.12, 128.97,
128.22, 125.09, 123.52, 118.83, 117.16, 116.64, 115.25, 113.19, 93.49
123

Chem. Pap.
Table 3 Antibacterial activities of compounds (3a–3q) against Xoo and Xcc in vitro
Compd.
Xoo
Xcc
R
200 (lg mL-1
)
100 (lg mL-1
)
200 (lg mL-1
)
100 (lg mL-1
)
3a
3b
3c
3d
3e
3f
H
61.2 1.1
52.1 2.3
49.0 2.5
50.4 2.0
48.1 2.1
92.7 2.6
88.1 2.3
90.5 1.5
84.2 2.0
88.6 1.3
97.3 1.4
98.6 1.7
94.1 2.4
95.2 1.3
92.4 3.3
43.5 2.1
96.0 1.2
68.7 2.1a
30.4 2.1
23.5 1.2
24.3 1.3
27.2 1.6
26.4 2.1
54.3 1.2
52.3 1.2
49.6 3.1
45.0 1.4
49.9 1.5
55.7 1.5
57.8 1.7
53.4 4.3
55.6 1.4
52.68 2.2
22.3 1.7
56.3 1.2
33.5 1.7a
67.2 1.6
57.4 1.3
55.2 1.2
55.7 3.5
56.1 3.2
93.8 3.4
89.6 1.2
93.1 1.3
85.2 3.9
87.3 1.2
98.1 1.2
99.2 2.2
96.1 1.8
97.3 3.6
93.2 1.4
61.9 2.3
97.1 2.1
76.2 1.3a
30.6 1.3
33.2 1.6
30.2 1.4
31.0 2.7
28.1 2.3
40.1 2.7
45.3 2.8
52.4 1.4
48.6 2.5
50.7 1.0
63.2 2.5
65.2 1.2
60.1 1.1
62.6 2.5
54.4 2.8
33.0 2.3
60.7 2.2
51.2 1.2a
2-Me
2-OMe
4-OMe
4-CH(CH3)2
3-F
3g
3h
3i
3-Cl
2,4-diCl
2-Br
3j
4-Br
3k
3 l
3m
3n
3o
3p
3q
2-NO2
4-NO2
2-OCF3
4-OCF3
4-F
4-Me
4-CF3
Thiodiazole-copper
a
(Chen et al. 2016)
relative inhibitory rate (I, %) compared with a blank assay
was calculated as follows:
data, absorption bands at 3341 cm-1are assigned to N–H of
amide, and absorption bands of the –OC=O– and –
NHC=O– of the skeleton-stretching frequency appeared at
I (%) = (Ctur - Ttur)/Ctur 9 100.
1
Ctur is the corrected turbidity value of bacterial growth
on untreated NB and Ttur is the corrected turbidity value of
bacterial growth on treated NB.
1704 and 1624 (all in cm-1), respectively. In H NMR
spectra, a singlet ranging from d 10.52 ppm belonged to
the –NHC=O– proton of compound 3a, the 3 position
proton of coumarin yielding singlet peak and appeared at d
5.31 ppm. The chemical shifts at d 93.49 ppm confirmed
the existences of 3-C of coumarin ring in 13C NMR.
Similarly, the solvent of Xoo was SM (10.0 g of pep-
tone, 5.0 g of glucose, 1.0 g of casein acid hydrolysate,
1000 mL of distilled water, pH 7.0–7.2), and thiodiazole-
copper was used as a positive control. Finally, the title
compounds were tested against Xoo and Xoo at five double-
declining concentration [200, 100, 50, 25, and 12.5 (all in
lg mL-1)], and EC50 of the test compounds was calculated
with SPSS 17.0.
Antibacterial activity
The preliminary bioassays result indicated that most of the
title compounds exhibited significant antibacterial activi-
ties against Xoo and Xcc in vitro (Table 3). Out of the title
compounds, 3f, 3h, 3k, 3l, 3m, 3n, 3o and 3q showed
excellent antibacterial activities against Xoo at
200 lg mL-1, with inhibition rates of 92.7, 90.5, 97.3,
98.6, 94.1, 95.2, 92.4 and 96.0%, respectively, which were
better than that of the commercial bactericide thiodiazole-
copper (63.1%). Meanwhile, the antibacterial activities of
compounds 3f, 3h, 3k, 3l, 3m, 3n, 3o and 3q against Xoo at
100 lg mL-1 were 55.1, 52.3, 55.7, 57.8, 52.1, 55.0, 52.6
and 56.3%, respectively, which were exceeding than that of
thiodiazole-copper (30.2%). Additionally, antibacterial
activities of compounds 3a, 3b, 3c, 3d, 3e and 3p were less
Results and discussion
Synthesis
The title compounds were synthesized from 4-hydroxy-
coumarin, 4-aminophenol, and aromatic acid in three steps
including chlorination, etherification, and condensation
reactions. The structures of the title compounds were
1
characterized by IR, H NMR, 13C NMR and elemental
analyses. Compound 3a as examples, in the IR spectral
123

Chem. Pap.
with different type aryl groups were deduced on the basis
of the antibacterial activities. When R was substituted with
electron-withdrawing group (F, Cl, Br, NO2, CF3, and
OCF3), corresponding title compounds showed excellent
antibacterial activities against Xoo and Xcc. Meanwhile,
when R was substituted with electron-donating group (Me,
OMe, and i-Pr), corresponding title compounds showed
poor antibacterial activities against Xoo and Xcc. More-
over, the title compounds bearing the same R showed
better antibacterial activities against Xcc than that of
antibacterial activities against Xoo. Lastly, it was found
that most of amide derivatives containing coumarin moiety
exhibited better antibacterial activities against Xoo and Xcc
than those of corresponding imine derivatives containing
same coumarin moiety when R was the same group (Chen
et al. 2016).
Table 4 EC50 of the compounds (3a–3q) against Xoo and Xcc
Compound
EC50 (lg mL-1
)
Xoo
Xcc
3a
233.2 2.1
268.3 1.5
283.7 2.7
279.4 1.9
294.3 2.3
135.8 2.2
156.0 2.9
145.7 1.5
178.5 1.1
160.2 2.3
103.6 1.8
96.4 2.6
221.5 1.7
216.2 2.3
229.7 2.6
226.3 1.5
237.9 1.2
115.0 2.7
138.1 2.5
101.2 1.8
142.4 1.3
136.8 1.1
79.4 2.5
73.2 1.5
119.0 2.0
112.4 1.2
107.4 2.0
218.3 1.8
83.1 2.3
138.3 1.3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
126.8 1.3
119.0 1.5
127.3 1.7
271.2 1.2
117.5 2.3
203.6 1.2a
3n
Conclusion
3o
3p
In summary, a series of novel amide derivatives containing
coumarin have been synthesized in appreciable yield and
spectral data were found in agreement with the assigned
molecular structures. Bioassay results indicated that com-
pounds 3f, 3g, 3h, 3i, 3j, 3k, 3l, 3m, 3n, 3o and 3q
exhibited excellent antibacterial activities against Xoo and
Xcc in vitro, which were better than thiodiazole-copper. To
the best of our knowledge, this is the first report on the
synthesis, antibacterial and antiviral activities of novel
amide derivatives containing coumarin.
3q
Thiodiazole-copper
a
(Chen et al. 2016)
than that of thiodiazole-copper at 200 and 100 (all in
lg mL-1). Similarly, compounds 3f, 3h, 3k, 3l, 3m, 3n, 3o
and 3q showed satisfactory antibacterial activities against
Xcc, with the inhibition rates of 93.8, 93.7, 98.1, 99.2, 96.1,
97.3, 93.2, and 97.0%, respectively, which were close to
that of thiodiazole-copper (86.2%) at 200 lg mL-1
.
Compounds 3f, 3h, 3k, 3l, 3m, 3n, 3o and 3q showed good
antibacterial activities against Xcc (52.4, 50.7, 63.2, 65.2,
Acknowledgements This work was financially supported by the
Science and Technology Fund of Guizhou Province (No.
[2011]2080), Natural Science Fund of Guizhou Province Education
(No. 2010079) and Dr. Fund of Tongren University (No.
trxyDH1618).
60.1, 62.6, 54.4 and 60.7%, respectively) at 100 lg mL-1
which compared with thiodiazole-copper (57.3%).
,
Based on the preliminary bioassays, EC50 of the title
compounds as well as thiodiazole-copper is listed in
Table 4. Notably, compounds 3f, 3g, 3h, 3i, 3j, 3k, 3l, 3m,
3n, 3o and 3q exhibited excellent antibacterial activities
against Xoo, with EC50: 135.8, 156.0, 145.7, 178.5, 160.2,
103.6, 96.4, 126.8, 119.0, 127.3, and 117.5 (all in
lg mL-1), respectively, which were better than that of
thiodiazole-copper (203.6 lg mL-1). Meanwhile, com-
pounds 3f, 3g, 3h, 3i, 3j, 3k, 3l, 3m, 3n, 3o and 3q showed
good activities against Xcc in vitro, with EC50 115.0, 138.1,
101.2, 142.4, 136.8, 79.4, 73.2, 119.0, 112.4, 107.4, and
83.1 (all in lg mL-1), respectively, which were better than
that of thiodiazole-copper (138.3 lg mL-1).
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