Synthesis and investigation of antimicrobial activity of some nifuroxazide analogues

Article abstract of DOI:10.14233/ajchem.2015.18896

A series of nifuroxazide analogues [(2a-2e)-(10a-10f)] have been synthesized, structurally identified and tested for antimicrobial activity against a panel of bacteria (Gram-positive and Gram-negative) and the yeast-like pathogenic fungus Candida albicans. The most active compound in this series was 4-amino-benzoic acid (5-nitro-furan-2-ylmethylene)-hydrazide (2b) and 2-amino-benzoic acid (5-nitrofuran-2-ylmethylene)-hydrazide (2d). Furthermore, compounds (9a-9g) and (10a-10g) recorded no activity against selected species except compounds (9f) and (10f) suggesting that using furoic hydrazide and the corresponding hydrazide of thiophene did not improve the antimicrobial activities for this type of compounds. Regarding the activity against Candida albicans, all compounds showed no activity with an exception of substituted nitro furan (2a-2d).

Full text of DOI:10.14233/ajchem.2015.18896

Asian Journal of Chemistry; Vol. 27, No. 10 (2015), 3639-3646
A
SIAN
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OURNAL OF HEMISTRY
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http://dx.doi.org/10.14233/ajchem.2015.18896
Synthesis and Investigation of Antimicrobial Activity of Some Nifuroxazide Analogues
1,*
1
2
HUDA S. ALSAEEDI , NABILA A. ALJABER and ISMET ARA
1Women Students-Medical Studies and Sciences Sections, Department of Chemistry, College of Science, King Saud University, P.O. Box
22452, Riyadh 11495, Saudi Arabia
2Botany and Microbiology Department, College of Science, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia
*Corresponding author: Tel: +966 11 4755798; E-mail: hualsaeedi@hotmail.com
Received: 2 December 2014;
Accepted: 14 January 2015;
Published online: 22 June 2015;
AJC-17317
A series of nifuroxazide analogues [(2a-2e)-(10a-10f)] have been synthesized, structurally identified and tested for antimicrobial activity
against a panel of bacteria (Gram-positive and Gram-negative) and the yeast-like pathogenic fungus Candida albicans. The most active
compound in this series was 4-amino-benzoic acid (5-nitro-furan-2-ylmethylene)-hydrazide (2b) and 2-amino-benzoic acid (5-nitro-
furan-2-ylmethylene)-hydrazide (2d). Furthermore, compounds (9a-9g) and (10a-10g) recorded no activity against selected species except
compounds (9f) and (10f) suggesting that using furoic hydrazide and the corresponding hydrazide of thiophene did not improve the
antimicrobial activities for this type of compounds. Regarding the activity against Candida albicans, all compounds showed no activity
with an exception of substituted nitro furan (2a-2d).
Keywords: Nifuroxazide, Hydrazide-hydrazone, Antimicrobial activity.
Nitrofurans are a class of drugs typically used as antibiotics
or antimicrobials12. Many drugs of interest for bacteriology
have been found in this broad class of compounds. As will as
hydrazone group that is an important group that possess a
recognized antimicrobial activity. Furthermore, a number of
hydrazide-hydrazones structure have been demonstrated to
possess interesting as antimicrobial1,3, antituberculosis5,7,
antiparasitic13, anti-inflammatory14, anti-tumour15, anti-HIV16,
inhibitor of anthrax lethal factor17, anticonvulsant18, analgesic
and antiplatelet activities19.
This study was aimed to synthesize, structurally identified
and tested for antimicrobial activity of series of nifuroxazide
analogues (Fig. 2) against two Gram-positive bacteria [Staphy-
lococcus aureus (ATCC 25923); Bacillus subtilis (ATCC
6633)]; three Gram-negative bacteria [EC: Escherichia coli
(ATCC 25922); ST: Salmonella susi (ATTC 13070); PA:
Pseudomonas aeruginosa (ATCC27853)] and one Fungus
[Candida albicans (ATCC 10231)].
INTRODUCTION
Development of antimicrobial agents to treat infections
has been one of the most notable medical achievements of the
past century1. As well as the development of resistance of
bacteria against these antimicrobial agents has become a
widespread medical concern, especially with the appearance
of nosocomial pathogens1-3. Because of this critical situation,
much effort has been directed to design new drugs by molecular
modification, which considers a quite promising strategy in
the design and development of drug analogues4,5.
Nifuroxazide (NXZ, Fig. 1) is one of the synthetic anti-
microbial agents which has wide spectrum of activity2-11. It
was demonstrated that the pharmacological activity is mainly
due to its configuration and is greatly diminished if the nitro
group is shifted from position 5 to either position 4 or 39. The
antimicrobial activities of nifuroxazide are related to tow major
antimicrobial classes nitrofurans class and hydrazide-hydra-
zone class Fig. 1.
EXPERIMENTAL
Melting points (°C, uncorrected) were determined using
an electrothermal’s IA9000 series digital capillary melting
point apparatus. IR spectra (KBr disks) were recorded on a
Perkin Elmer FT spectrophotometer 1000. 1H and 13C NMR
spectra were recorded on a JEOL ECP 400 NMR spectrometer
operating at 400 MHz using DMSO-d6 as solvents with TMS
O
N
N
O2N
O
H
OH
Fig. 1. Nifuroxazide classification

3640 Alsaeedi et al.
Asian J. Chem.
O
X'
R2
X
Ar
N
X'
CO
CO
CO
CO
SO2
4-OH
4-NH2
2-OH
2-NH2
4-CH3
N
N
N
H
R1
X
H
R2
X: O, S
Ar; 4-C6H5OH, 4-C6H5NO2, 2,4-C6H4(OH)2,
2,4-C6H4(NO2)2, furan-2-yl,5-Nitro-furan-2-yl
X:O, R1: H, NO2, CH2OH, Br, 4-C6H5Br
X: S, NH R1: H
Fig. 2. Molecular modification of nifuroxazide
as internal standard, Chemical shifts are given in ppm (δ-scale)
replacing the furan ring with thiophene and pyrrole. The
compounds [(9a-9f)- (10a-10f)] were also prepared from the
reaction of furoic hydrazide and the corresponding hydrazide
of thiophene with a variety of aromatic aldehydes, furan-2-
carboxaldehyde and thiophene-2-carboxaldehyde in ethanol
absolute ethanol under reflux for 2 h. The progress of the reac-
tion was monitor by TLC. The insoluble product was filtered off.
4-Hydroxy-benzoic acid 5-nitro-furan-2-ylmethylene-
hydrazide (2a): Yellow powder; Yield 91.40 %; m.p. 280-
and the coupling constants are given in Hertz. Monitoring the
reactions and checking the purity of the final product were
carried out by thin layer chromatography using TLC pre-coated
silica gel sheets (60 F254, Merck) and ethanol-chloroform (1:9)
as eluent. The spots were detected by exposure to UV-lamp at
λ 254 nm for few seconds.
Synthesis: Substituted benzhydrazides (1a-1d) were
synthesized from respective methyl substituted benzoate (1
mmol) with hydrazine hydrate 99 % (30 mmol) under reflux
for 3-4 h. The solid product obtained after cooling was filtered
off and dried2. Benzhydrazides (1a) and p-toluenesulfonyl
hydrazide (1e) have been synthesized by adding (10 mmol) of
50 % hydrazine hydrate with benzoyl chloride (1 mmol) and
p-toluenesulfonyl chloride (1 mmol) respectively under reflux
for 0.5 h. The solid products were collected after cooling and
dried1.
4-Hydroxy-benzoic acid hydrazide (1a): White powder;
m.p. 114 °C; IR (cm–1): 3275-3296 ν(N–H and NH2); 1669
ν(C=O); 1H NMR (DMSO-d6): 10.70 (1H, s, OH); 9.08 (1H,
s, NH); 7.71 (d, J = 8.79, 2H, H2 and H6); 6.89 (d, J = 8.79,
2H, H3 and H5); 4.78 (2H, s, NH2).
4-Amino-benzoic acid hydrazide (1b): White powder;
m.p. 225 °C; IR (cm–1): 3233-3300 ν(N–H and NH2); 1660
ν(C=O); 1H NMR (DMSO-d6): 9.15 (1H, s, NH); 7.51 (d, J =
8.79, 2H, H2 and H6); 6.56 (d, J = 8.79, 2H, H3 and H5);
5.43 (s, 2H, NH2); 4.04 (2H, s, NH2).
2-Hydroxy-benzoic acid hydrazide (1c): White powder;
m.p. 149 °C; IR (cm–1): 3200-3300 ν(N–H and NH2); 1660
ν(C=O); 1H NMR (DMSO-d6): 12.47 (s, 1H, OH); 10.04 (1H,
s, NH); 7.77 (d, 1H, H6); 7.36 (t, 1H, H4); 6.86-6.84 (m, 2H,
H5 and H3); 4.62 (2H, s, NH2).
2-Amino-benzoic acid hydrazide (1d): Beige powder;
Yield: 87.61 %; IR (cm–1): 3269-3319 ν(N–H and NH2); 1645
ν(C=O); 1H NMR (DMSO-d6): 9.46 (1H, s, NH); 7.41 (d.d, J
= 8.05, J = 1.44, 1H, H5); 7.10 (t.d, J = 8.25, J = 1.47, 1H,
H4); 6.68 (d.d, J = 8.80, J = 1.11, 1H, H6); 6.46 (t.d, J = 7.87,
J = 1.11, 1H, H3); 6.32 (s, 2H, NH2); 4.36 (2H, s, NH2).
p-Toluenesulfonyl hydrazide (1e): White powder; m.p.
106-108 °C; IR (cm–1): 3389-3260 ν(N–H and NH2); 1H NMR
(DMSO-d6): 8.32 (1H, s, NH); 7.72 (d, J = 8.79, 2H, H2 and
H6); 7.39 (d, J = 8.79, 2H, H3 and H5); 4.01 (s, 2H, NH2);
2.29 (3H, s, CH3).
Synthesis: The target compounds (2a-2e)-(6a-6f) were
synthesized by reacting equimolar proportion of substituted
benzhydrazides and benzenesulfonyl hydrazide with 5-substi-
tuted 2-furan carboxaldehyde in ethanol absolute under reflux2
for 2 h. Compounds [(7a-7e)-(8b-8e)] were synthesized by
1
282 °C; IR 3365 ν(O–H); 3245 ν(N–H); 1674 ν(C=O); H
NMR (DMSO-d6): 10.04 (s, 1H, NH); 10.24 (s, 1H, OH); 8.37
(s, 1H, CH=N); 7.82 (d, J = 8.08.2 H, H2' and H6'); 7.77 (d, J
= 3.64, 1H, H4); 7.22 (d, J = 4.4, 1H, H3); 6.88 (d, J = 8.8,
2H, H3' and H5'); 13C NMR: 163.20 (CO); 161.66 (C-4');
152.61 (C-5); 152.35 (C-2); 134 (CH); 130.52 (C-2' and C-
6'); 123.71 (C-1'); 115.70 (C-3' and C-5'); 115.38 (C-4); 115.27
(C-3); MS: C12H9N3O5+., M+ 275 (5.00 %); M+1 276.27 (100
%); C12H10N2O3+., m/z 130.27 (9 %); C7H7NO2+, m/z 137.18
(70 %); C7H5O2+, m/z 121.35 (20 %); C5H5N3O3+, m/z 155.27
(37 %); C5H2N2O3+, m/z 138 (12 %).
4-Amino-benzoic acid 5-nitro-furan-2-ylmethylene-
hydrazide (2b): Red powder; Yield 92.42 %; m.p. >300 °C;
1
IR (cm–1): 3452-3313 ν(N–H); 1664 ν(C=O); H NMR
(DMSO-d6): 11.89 (s, 1H, NH); 8.34 (s, 1H, CH=N); 7.76 (d,
J = 3.64, 1H, H4); 7.69 (d, J = 8.56.2H, H2' and H6'); 7.18 (d,
J = 3.68, 1H, H3); 6.62 (d, J = 8.56, 2H, H3' and H5'); 5.89 (s,
2H, NH2);13C NMR: 163.91 (CO); 153.32 (C-5); 152.90 (C-2);
152.25 (C-4'); 134.07 (CH); 130.27 (C-2' and C-6'); 119.15
(C-1'); 115.38 (C-4); 114.92 (C-3); 113.22 (C-3' and C-5').
2-Hydroxy-benzoic acid 5-nitro-furan-2-yl-methylene-
hydrazide (2c): Yellow fine scales;Yield 88.56 %; m.p. 257-
259 °C; IR (cm–1): 3465 ν(O–H); 3227 ν(N–H); 1630 ν(C=O);
1H NMR (DMSO-d6): 12.11 (s, 1H.NH); 11.52 (s, 1H, OH);
8.42 (s, 1H, CH=N); 7.84 (d, J = 8.08, 1H, H6'); 7.81 (d, J =
3.64, 1H, H4); 7.45 (t, J = 8.04, 1H, H4'); 7.28 (d, J = 3.68,
1H, H3); 6.98 (t, J = 8.08, 1H, H5'); 6.97 (d, J = 7.36, 1H,
H3'); 13C NMR: 165.19 (CO); 158.86 (C-2'); 152.53 (C-5);
152.15 (C-2); 136.65 (CH); 134.55 (C-4'); 129.64 (C-6');
119.72 (C-5'); 117, 73 (C-1'); 117.08 (C-4); 116.16 (C-3);
115.18 (C-3').
2-Amino-benzoic acid 5-nitro-furan-2-yl-methylene-
hydrazide (2d): Yellow powder; Yield 93.55 %; m.p. 213-
214 °C; IR (cm–1): 3395, 3306-3234 ν(N–H); 1659 ν(C=O);
1H NMR (DMSO-d6): 12.01 (s, 1H.NH); 8.33 (s, 1H, CH=N);
7.79 (d, J = 404, 1H, H4); 7.85 (d, J = 8.08, 1H, H6'); 7.23-
7.21 (m, 2H, H4' and H3); 6.78 (d, J = 8.04, 1H, H3'); 6.58 (t,
J = 7.32, 1H, H5'); 6.48 (s, 2H, NH2);13C NMR: 166.08 (CO);
152.65 (C-5); 152.35 (C-2); 150.98 (C-2'); 134.87 (CH);

Vol. 27, No. 10 (2015)
Synthesis and Investigation of Antimicrobial Activity of Some Nifuroxazide Analogues 3641
133.36 (C-4'); 128.96 (C-6'); 117.10 (C-5'); 115.31 (C-4 and
C-3'); 115.18 (C-1'); 113.01 (C-3).
2H, H2' and H6'); 6.86 (d, J = 8.084, 2H, H3' and H5'); 6.82
(d, J = 2.2, 1H, H3); 6.44 (d, J = 2.96, 1H, H4); 5.42 (s, 1H,
OH); 4.45 (s, 2H, CH2). 13C NMR: 163.20 (CO); 161.23 (C-4');
158.17 (C-5); 149.36 (C-2); 137.08 (C=NH); 130.19 (C-2' and
C-6'); 124.35 (C-1'); 115.57 (C-3' and C-5'); 114.74 (C-3);
109.72 (C-4); 56.28 (CH2).
4-Amino-benzoic acid 5-hydroxymethyl-furan-2-
ylmethylene-hydrazide (4b): Brown powder;Yield 95.79 %;
m.p.182-184 °C; IR (cm–1): 3261 ν(N–H); 1685 ν(C=O), 1H
NMR (DMSO-d6): 11.84 (1H, s, NH); 8.23 (1H, s, CH); 7.65
(d, J = 8.8, 2H, H2' and H6'); 6.78 (d, J = 2.92, 1H, H3); 6.59
(d, J = 8.8, 2H, H3' and H5'); 6.44 (d, J = 2.92, 1H, H4); 5.79
(s, 2H, NH2); 5.42 (d, J = 5.84 1H, OH); 4.45 (d, J = 5.12 2H,
CH2); 13C NMR: 157.94 (C-5); 157.73 (CO); 152.84 (C-4');
149.55 (C-2); 136.23 (CH=N); 129.88 (C-2' and C-6'); 119.95
(C-1'); 114.21 (C-3); 113.14 (C-3' and C-5'); 109.68 (C-4);
56.27 (CH2).
4-Methyl-benzenesulfonyl (5-nitro furan-2-yl-methy-
lene)hydrazide (2e): Yellow plates;Yield 55.94 %; m.p. 130-
1
131 °C; IR (cm–1): 3180 ν(N–H); 1355-1158 ν( (S=O)2); H
NMR (DMSO-d6): 12.14 (s, 1H, NH); 7.86 (s, 1H, CH=N);
7.76 (d, J = 8.04, 2H, H2' and H6'); 7.71 (d, J = 3.68, 1H,
H4); 7.43 (d, J = 8.08, 2H, H3' and H5'); 7.13 (d, J = 3.68,
1H, H3); 2.37 (s, 3H, CH3); 13C NMR: 152.37 (C-5); 151.27
(C-2); 144.45 (C-4'); 136.44 (C-1'); 135.21 (CH); 130.45 (C-
3' and C-5'); 127.68 (C-2' and C-6'); 115.90 (C-4); 114.99 (C-
3); 21 (CH3).
4-Hydroxy-benzoic acid furan-2-yl-methylene-hydra-
zide (3a): Yellowish white plates; Yield 73.39 %; m.p. 221-
223 °C; IR (cm–1): 3460 ν(O–H); 3254 ν(N–H); 1617 ν(C=O);
1H NMR (DMSO-d6): 11.59 (1H, s, NH); 10.11 (s, 1H, OH);
8.32 (1H, s, CH=N); 7.83 (s, 1H, H5); 7.79 (d, J = 8.08, 2H,
H2' and H6'); 6.89 (d, J = 2.2, 1H, H3); 6.87 (d, J = 8.8, 2H,
H3' and H5'); 6.63 (t, J = 2.2, 1H, H4);13C NMR:163.23 (CO);
161.25 (C-4'); 150.17 (C-2); 145.51 (C-5); 137.24 (CH);
130.19 (C-3' and C-5'); 124.51 (C-1'); 115.58 (C-3' and C-5');
113.54 (C-3); 112.71 (C-4).
2-Hydroxy-benzoic acid 5-hydroxymethyl-furan-2-
ylmethylene-hydrazide (4c): Yellowish white plate; Yield
93.61 %; m.p. 171-172 °C; IR (cm–1): 3470 ν(O–H); 3275
1
ν(N–H); 1630 ν(C=O); H NMR (DMSO-d6): 12.20 (s, 1H,
OH); 11.77 (1H, s, NH); 8.30 (1H, s, CH); 7.56 (d, J = 8.08,
1H, H6'); 7.44 (t, J = 8.8, 1H, H4'); 6.99-6.93 (m, 2H, H3' and
H5'). 6.89 (d, J = 2.92, 1H, H3); 6.47 (d, J = 2.92, 1H, H4);
4.59 (s, 1H, OH); 4.47 (s, 2H, CH2); 13C NMR: 165.26 (CO);
159.59 (C-2'); 158.71 (C-5); 148.96 (C-2); 138.81 (CH=N);
134.37 (C-4'); 129.60 (C-6'); 119.47 (C-5'); 117.83 (C-1');
116.41 (C-3'); 115.94 (C-3); 109.82 (C-4); 56.52 (CH2).
2-Amino-benzoic acid 5-hydroxymethyl-furan-2-
ylmethylene-hydrazide (4d): Yellowish plate;Yield 95.94 %;
m.p.177-178 °C; IR (cm–1): 3200 ν(N–H); 1620 ν(C=O), 1H
NMR (DMSO-d6): 11.53 (1H, s, NH); 8.22 (1H, s, CH); 7.53
(d, J = 8.04, 1H, H6'); 7.19 (t, J = 8.08, 1H, H4'); 6.82 (d, J =
2.96, 1H, H3); 6.76 (d, J = 8.08, 1H, H3'); 6.56 (t, J = 8.05,
1H, H5'); 6.44 (d, J = 2.92, 1H, H4); 6.37 (s, 2H, NH2); 5.42
(s, 1H, OH); 4.45 (d, J = 5.12, 2H, CH2); 13C NMR: 162.80
(CO); 158.18 (C-5); 150.56 (C-2'); 149.38 (C-2); 137.07
(CH=N); 132.82 (C-4'); 128.81 (C-6'); 116.92 (C-5'); 115.18
(C-3'); 114.66 (C-3); 113.32 (C-1'); 109.73 (C-4); 56.28 (CH2).
4-Hydroxy-benzoic acid 5-bromo-furan-2-ylmethylene-
hydrazide (5a): Beige powder; Yield 94.26 %; m.p.175-176
°C; IR (cm–1): 3484 ν(O–H); 3247 ν(N–H); 1635 ν(C=O); 1H
NMR (DMSO-d6): 11.66 (s, 1H, NH); 10.15 (s, 1H, OH); 8.23
(s, 1H, CH=N); 7.79 (d, J = 8.8, 2H, H2' and H6'); 6.94 (d, J =
3.68, 1H, H4); 6.87 (d, J = 8.8, 2H, H3' and H5'); 6.75 (d, J =
3.68, 1H, H3); 13C NMR: 163.29 (CO); 161.31 (C-4'); 152.12
(C-2); 135.97 (CH); 130.25 (C-2' andC-6'); 124.85 (C-5);
124.20 (C-1'); 116.26 (C-4); 115.74 (C-3' and C-5'); 114.73
(C-3).
4-Amino-benzoic acid furan-2-ylmethylene-hydrazide
(3b): Beige powder;Yield 75.76 %; m.p. 190-191 °C; IR (cm–1):
1
3232-3390-3300 ν(N–H); 1638 ν(C=O); H NMR (DMSO-
d6): 11.43 (1H, s, NH); 8.30 (1H, s, CH=N); 7.81 (s, 1H, H5);
7.67 (d, J = 8.8, 2H, H2' and H6'); 6.85 (d, J = 3.68, 1H, H3);
6.61 (3, J = 3.64, 1H, H4); 6.60 (d, J = 8.8, 2H, H3' and H5');
5.80 (s, 2H, NH2); 13C NMR:163.65 (CO); 152.87 (C-4');
150.38 (C-2); 145.28 (C-5); 136.43 (CH); 129.92 (C-2' and
C-6'); 119.94 (C-1'); 113.17 (C-3' and C-5'); 113.02 (C-3);
112.66 (C-4).
2-Hydroxy-benzoic acid furan-2-yl-methylene-hydra-
zide (3c): Beige powder;Yield 77.55 %; m.p. 222-224 °C; IR
(cm–1): 3470 ν(O–H); 3247 ν(N–H); 1635 ν(C=O); 1H NMR
(DMSO-d6): 11.83 (1H, s, NH); 11.80 (s, 1H, OH); 8.35 (1H,
s, CH=N); 7.87 (d, J = 8.04, 1H, H6'); 7.88 (s, 1H, H5); 7.66
(d, 1H, H3); 7.44 (t, J = 8.08, 1H, H4'); 6.97 (m, 2H, H3', H5'
and H4); 13C NMR:165.29 (CO); 159.55 (C-2'); 149.79 (C-2);
146.02 (C-5); 138.93 (CH); 134.38 (C-4'); 129.02 (C-6');
119.50 (C-5'); 117.82 (C-1'); 116.45 (C-3'); 114.70 (C-3);
112.84 (C-4).
4-Methyl-benzenesulfonyl (furan-2-yl-methylene)-
hydrazide (3e): Yellowish brown cubes;Yield 84.16 %; m.p.
110-112 °C; IR (cm–1): 3154 ν(N–H); 1316-1168 ν( (S=O)2);
1350 ν(CH3); 1H NMR (DMSO-d6): 11.44 (1H, s, NH); 7.78
(1H, s, CH=N); 7.75 (d, J = 1.48, 1H, H5); 7.73 (d, J = 8.08,
2H, H2' and H6'); 7.40 (d, J = 8.08, 2H, H3' and H5'); 6, 80
(d, J = 2.92, 1H, H3); 6.55 (d.d, J = 3.28, J = 2.2, 1H, H4);
2.35 (s, 3H, CH3); 13C NMR: 147.90 (C-2); 144.38 (C-5);
142.83 (C-4'); 136.27 (C-1'); 135.43 (CH); 129.03 (C-3’and
C-5'); 126.51 (C-2'and C-6'); 113.27 (C-3); 111.34 (C-4); 20.31
(CH3).
4-Amino-benzoic acid 5-bromo-furan-2-ylmethylene-
hydrazide (5b): Orange fine needles;Yield 95.34 %; m.p. > 300
°C; IR (cm–1): 3225 ν(N–H); 1620 ν(C=O); 1H NMR (DMSO-
d6): 11.49 (1H, s, NH); 8.21 (1H, s, CH=N); 7.66 (d, J = 8.56,
2H, H2' and H6'); 6.90 (d, J = 3.68, 1H, H4); 6.74 (d, J =
3.68, 1H, H3); 6.61 (d, J = 8.56, 2H, H3' and H5'); 5.81 (s,
2H, NH2);13C NMR: 163.55 (CO); 152.96 (C-4'); 152.32 (C-2);
135.13 (CH); 129.96 (C-2' and C-6'); 124.54 (C-5); 119.76
(C-1'); 115.74 (C-4); 114.66 (C-3); 113.16 (C-3' and C-5').
4-Hydroxy-benzoic acid 5-hydroxymethyl-furan-2-
ylmethylene-hydrazide (4a): Yellowish white plate; Yield
86.15 %; m.p. 202-203 °C; IR (cm–1): 3400 ν(O–H); 3257
1
ν(N–H); 1630 ν(C=O); H NMR (DMSO-d6): 11.57 (1H, s,
NH); 10.14 (1H, s, OH); 8.25 (1H, s, N=CH); 7.79 (d, J = 8.8,

3642 Alsaeedi et al.
Asian J. Chem.
2-Hydroxy-benzoic acid 5-bromo-furan-2-ylmethylene-
hydrazide (5c): Beige powder; Yield 89.32 %; m.p.219-221
°C; IR (cm–1): 3480 ν(O–H); 3245 ν(N–H); 1624 ν(C=O).1H
NMR (DMSO-d6): 11.76 (s, 1H, OH); 11.84 (1H, s, NH); 8.27
(1H, s, CH=N); 7.85 (d, J = 7.32, 1H, H6'); 7.43 (t, J = 7.36,
1H, H4'); 6.99 (m, 3H, H3, H3' and H5'); 6.78 (d, 1H, H4);13C
NMR: 165.28 (CO); 159.41 (C-2'); 151.74 (C-2); 137.64 (CH);
134.41 (C-4'); 129.13 (C-6'); 125.48 (C-5); 119.54 (C-5');
117.80 (C-4); 117.29 (C-3'); 116.51 (C-1'); 114.86 (C-3).
2-Amino-benzoic acid 5-bromo-furan-2-ylmethylene-
hydrazide (5d): Orange powder;Yield 76.25 %; m.p.133-134
°C; IR (cm–1): 3241 ν(N–H); 1653 ν(C=O); 1H NMR (DMSO-
d6): 11.64 (1H, s, NH); 8.20 (1H, s, CH=N); 7.55 (d, J = 8.08,
1H, H6'); 7.20 (t, J = 8.08, 1H, H4'); 6.93 (d, J = 3.68, 1H,
H4); 6.77 (d, J = 9.52, 1H, H3'); 6.74 (d, J = 3.68, 1H, H3);
6.57 (t, J = 7.32, 1H, H5'); 6.41 (s, 2H, NH2);13C NMR: 165.91
(CO); 152.15 (C-2); 150.64 (C-2'); 135.94 (CH); 132.95 (C-
4'); 128.85 (C-6'); 124.83 (C-5); 116.99 (C-4); 116.20 (C-5');
115.21 (C-3'); 114.73 (C-3); 113.75 (C-1').
4-Methyl-benzenesulfonyl(5-bromofuran-2-ylmethylene)-
hydrazide (5e): Beige powder; Yield 20.27 %; m.p.116-118
°C; IR (cm–1): 3175 ν(N–H); 1342-1185 ν(S (=O)2). 1H NMR
(DMSO-d6): 11.55 (1H, s, NH); 7.73 (d, J = 8.8, 2H, H2' and
H6'); 7.70 (1H, s, CH=N); 7.42 (d, J = 7.32, 2H, H3' and H5');
6.85 (d, J = 3.64, 1H, H4); 6.69 (d, J = 2.92, 1H, H3); 2.37 (s,
3H, CH3); 13C NMR: 151.09 (C-2); 144.13 (C-4'); 136.64 (C-
1'); 136.33 (CH=N); 130.33 (C-3' and C-5'); 127.67 (C-2' and
C-6'); 125.12 (C-5); 116.94 (C-4); 114.68 (C-3); 21.57 (CH3).
4-Hydroxy-benzoic acid 5-[4-bromophenyl]-furan-2-
ylmethylene-hydrazide (6a): Beige plates; Yield 81.29 %;
m.p. 162-164 °C; IR (cm–1): 3412 ν(O–H); 3231 ν(N–H); 1615
ν(C=O); 1504 and 1469 ν(C=C). 1H NMR (DMSO-d6): 11.67
(s, 1H, NH); 10.15 (s, 1H, OH); 8.36 (s, 1H, CH=N); 7.81 (d,
J = 8.04, 2H, H2' and H6'); 7.75 (d, J = 8.04, 2H, H3" and
H5"); 7.67 (d, J = 8.04, 2H, H2" and H4"); 6.20 (d, J = 3.68,
1H, H4); 7.03 (d, J = 3.68, 1H, H3); 6.88 (d, J = 8.8, 2H, H3'
and H5'); 13C NMR: 163.21 (CO); 161.28 (C-4'); 153.97 (C-
5); 150.19 (C-2); 136.92 (CH=N); 132.56 (C-3" and C-5");
130.22 (C-2' andC-6'); 129.29 (C-1"); 126.39 (C-2" and C-
6"); 124.32 (C-1'); 121.76 (C-4"); 116.21 (C-4); 115.60 (C-3'
and C-5'); 109.67 (C-3).
8.49, H3" and H5"); 7.68 (d, J = 8.79, H2" and H6"); 7.47-
7.41 (t.d, J = 7.56, J = 1.38, 1H, H4'); 7.23 (d, J = 3.57, H3);
7.10 (d, J = 3.75, H4); 6.99-6.93 (m, 2H, H3' and H5').
13C NMR: 164.27 (CO); 158.53 (C-2'); 153.45 (C-5); 148.81
(C-2); 133.43 (C-4'); 131.63 (C-3" and C-5"); 128.23 (C-1");
128.12 (C-6'); 125.53 (C-2" and C-6"); 120.98 (C-4"); 118.56
(C-5'); 116.87 (C-3'); 116.34 (C-4); 115.60 (C-1'); 108.79
(C-3).
2-Amino-benzoic acid 5-[4-bromophenyl]-furan-2-
ylmethylene-hydrazide (6d): White fine plates; Yield 90.18
%; m.p.213-214 °C; IR (cm–1): 3216 ν(N–H); 1627 ν(C=O);
1H NMR (DMSO-d6): 11.67 (1H, s, NH); 8.32 (1H, s, CH=N);
7.74 (d, J = 8.8, H3" and H5"); 7.66 (d, J = 8.04, H2" and
H6"); 7.58 (d, J = 8.08, 1H, H6'); 7.21 (t, J = 8.04, 1H, H4');
7.18 (d, J = 3.68, H3); 7.02 (d, J = 3.68, H4); 6.78 (d, J =
8.04, 1H, H3'); 6.58 (t, J = 7.36, 1H, H5'); 6.42 (s, 2H, NH2);
13C NMR:165.90 (CO); 153.99 (C-5); 150.20 (C-2'); 150.65
(C-2); 136.84 (CH); 132.91 (C-4'); 132.53 (C-3" and C-5");
129.28 (C-1"); 128.86 (C-6'); 126.37 (C-2" and C-6"); 121.77
(C-4"); 116.97 (C-5'); 116.18 (C-3'); 115.20 (C-4); 113.91 (C-
1'); 109.64 (C-3).
4-Methyl-benzenesulfonyl (5-[4-bromophenyl]-furan-
2-ylmethylene)-hydrazide (6e): Brown powder;Yield 85.20
%; m.p.168-170 °C; IR (cm–1): 3179 ν(N–H); 1323-1171 ν(S
(=O)2); 1H NMR (DMSO-d6): 11.53 (1H, s, NH); 7.81 (1H, s,
CH=N); 7.78 (d, J = 8.08, 2H, H2' and H6'); 7.67 (d, J = 8.8,
H3" and H5"); 7.64 (d, J = 8.8, H2" and H6"); 7.41 (d, J =
8.04, 2H, H3' and H5'); 7.11 (d, J = 3.68, H3); 6.92 (d, J =
3.64, H4); 2.33 (s, 3H, CH3);13C NMR: 153.99 (C-5); 149.16
(C-2); 144.08 (C-4'); 137.16 (CH); 136.68 (C-1'); 132.54 (C-
3" and C-5"); 130.26 (C-3' and C-5'); 129.11 (C-1"); 127.73
(C-2" and C-6"); 126.38 (C-2' and C-6'); 121.87 (C-4"); 116.51
(C-4); 109.45 (C-3), 21.55 (CH3).
4-Hydroxy-benzoic acid thiophen-2-ylmethylene-
hydrazide (7a): Beige powder; Yield 66.91 %; m.p.254-255
°C; IR (cm–1): 3390 ν(O–H); 3252 ν(N–H); 1634 ν(C=O); 1H
NMR (DMSO-d6): 11.62 (1H, s, NH); 10.14 (s, 1H, OH); 8.65
(1H, s, CH=N); 7.80 (d, J = 8.08, 2H, H2' and H6'); 7.64 (d, J
= 5.12, 1H, H5); 7.34 (d, J = 2.92, 1H, H3); 7.12 (t, J = 4.4,
1H, H4); 6.87 (d. J = 8.04, 2H, H3' and H5');13C NMR: 163.23
(CO); 161.24 (C-4'); 142.60 (CH); 139.93 (C-2' and C-6');
131.06, 130.19 (C-3 and C-4); 129.18 (C-1'); 128.37 (C-3'
and C-5'); 124.38, 115.59 (C-2 and C5).
4-Amino-benzoic acid 5-[4-bromophenyl]-furan-2-
ylmethylene-hydrazide (6b): Yellowish white plates; Yield
77.03 %; m.p. 206-208 °C; IR (cm–1): 3219 ν(N–H); 1612
ν(C=O); 1H NMR (DMSO-d6): 11.52 (1H, s, NH); 8.35 (1H,
s, CH=N); 7.72 (d, J = 8.52, 2H, H3" and H5"); 7.69 (d, J =
8.56, 2H, H2' and H6'); 7.64 (d, J = 8.52, 2H, H2" and H6");
7.17 (d, J = 2.76, 1H, H H3); 6.98 (d, J = 2.76, 1H, H4). 6.61
(d, J = 8.56, 2H, H3' and H5'); 5.82 (s, 2H, NH2); 13C NMR:
162.85 (CO); 153.02 (C-5); 152.08 (C-4'); 149.48 (C-2);
136.10 (CH); 131.74 (C-3" and C-5"); 129.14 (C-1"); 128.47
(C-2' and C-6'); 125.54 (C-2" and C-6"); 120.90 (C-4"); 118.94
(C-1'); 115.04 (C-4); 112.40 (C-3’and C-5'); 108.80 (C-3).
2-Hydroxy-benzoic acid 5-[4-bromophenyl]-furan-2-
ylmethylene-hydrazide (6c): Yellow powder;Yield 90.12 %;
m.p. 261-263 °C; IR (cm–1): 3450 ν(O–H); 3248 ν(N–H); 1621
4-Amino-benzoic acid thiophen-2-ylmethylene-
hydrazide (7b): Beige powder; Yield 55.39 %; m.p.176-177
°C; IR (cm–1): 3205 ν(N–H); 1620 ν(C=O); 1H NMR (DMSO-
d6): 11.43 (1H, s, NH); 8.62 (1H, CH=N); 7.66 (d, J = 8.8,
2H, H2' and H6'); 7.62 (d, J = 5.16, 1H, H5); 7.40 (d, J =
5.16, 1H, H3); 7.12 (t, J = 3.64, 1H, H4); 6.60 (d, J = 8.08,
2H, H3' and H5'); 5.79 (s, 2H, NH2);13C NMR: 163.45 (CO);
152.85 (C-4'); 141.68 (CH); 140.19, 130.63 (C-3 and C-4);
129.89, 128.86 (C-2 and C-5); 128.32 (C-2' and C-3'); 119.99
(C-1'); 113.15 (C-3' and C-5').
2-Hydroxy-benzoic acid thiophen-2-ylmethylene-
hydrazide (7c): Beige powder; Yield 92.74 %; m.p.241-243
°C; IR (cm–1): 3469 ν(O–H); 3245 ν(N–H); 1622 ν(C=O); 1H
NMR (DMSO-d6): 11.82 (s, 2H, NH, OH); 7.87 (d, J = 8.08,
1H, H6'); 7.71 (d, J = 5.12, 1H, H5); 7.50 (d, J = 3.68, 1H,
1
ν(C=O); H NMR (DMSO-d6): 11.85 (s, 2H, OH and NH);
8.38 (1H, s, CH=N); 7.87 (d.d, J = 6.6, 1H, H6'); 7.76 (d, J =

Vol. 27, No. 10 (2015)
Synthesis and Investigation of Antimicrobial Activity of Some Nifuroxazide Analogues 3643
H3); 7.44 (t, J = 8.08, 1H, H4'); 7.16 (t, J = 4.4, 1H, H4); 6.98
(d, J = 8.08, 1H, H3'); 6.95 (t, J = 8.08, 1H, H5'); 13C
NMR:165.12 (CO); 159.49 (C-2'); 144.30, 131.98 (C-3 and
C-4); 139.39 (CH); 134.35 (C-4'); 129.88, 129.05 (C-2 and
C5); 128.50 (C-6'); 119.50 (C-5'); 117.82 (C-3'); 116.51 (C-1').
2-Amino-benzoic acid thiophen-2-ylmethylene-
hydrazide (7d): Beige powder; Yield 51.02 %; m.p.174-175
°C; IR (cm–1): 3176 ν(N–H); 1635 ν(C=O); 1H NMR (DMSO-
d6): 11.59 (1H, s, NH); 8.59 (1H, s, CH=N); 7.65 (d, J = 5.16,
1H, H5); 7.55 (d, J = 8.04, 1H, H6'); 7.43 (d, J = 3.68, 1H,
H3); 7.20 (t, J = 8.08, 1H, H4'); 6.77 (d, J = 8.08, 1H, H3');
7.14-7.12 (d.d, J = 5.14, J = 3.68, 1H, H4); 6.57 (t, J = 8.08,
1H, H5'); 6.37 (s, 2H, NH2); 13C NMR:165.72 (CO); 150.56
(C-2'); 142.48, 139.94 (C-3 and C-4); 132.82 (C-4'); 131.05
(CH), 129.20, 128.83 (C-2 and C-5); 128.38 (C-6'); 116.93
(C-5'); 115.18 (C-3'); 114.01 (C-1').
4-Methyl-benzenesulfonyl(thiophen-2-ylmethylene)-
hydrazide (7e):Beige powder; Yield 78.75 %; m.p.144-146
°C; IR (cm–1): 3163 ν(N–H); 1341-1168 ν(S (=O)2); 1H NMR
(DMSO-d6): 11.39 (1H, s, NH); 8.10 (1H, s, CH=N); 7.85 (d,
J = 5.12, 1H, H5); 7.75 (d, J = 8.8, 2H, H2' and H6'); 7.40 (d,
J = 8.04, 2H, H3' and H5'); 7.35 (d, J = 3.68, 1H, H3); 7.06
(d.d, J = 5.12, J = 3.68, 1H, H4) 2.34 (s, 3H, CH3);13C NMR:
142.78 (C-4'); 138.83 (CH); 136.57 (C-1'); 144.05, 131.30
(C-3 and C-4); 130.19 (C-3' and C-5'); 129.26, 128.34 (C-2
and C-5); 127.76 (C-2' and C-6'); 21.55 (CH3).
(CH); 147.36 (C-2); 146.15 (C-5); 129.44 (C-2' and C-6'); 125.78
(C-1'); 116.29 (C-3' and C-5'); 115.15 (C-3); 112.58 (C-4).
Furan-2-carboxylic acid (4-nitro-benzylidene)hydra-
zide (9b): Yellow powder; Yield 96.24 %; m.p.184-176 °C;
1
IR (cm–1): 3278 ν(N–H); 1675 ν(C=O); H NMR (DMSO-
d6): 12.15 (1H, s, NH); 8.54 (1H, s, CH=N); 8.31 (d, J = 8.8,
2H, H3' and H5'); 7.98 (s, 1H, H5); 7.96 (d, J = 8.8, 2H, H2'
and H6'); 7.36 (s, 1H, H3); 6.73 (d.d, J = 3.68, J = 1.48, 1H,
H4); 13C NMR:154.89 (CO); 150.10 (C-4'); 148.38 (CH);
146.79 (C-2); 145.85 (C-5); 141.09 (C-1'); 128.56 (C-2' and
C-6'); 124.65 (C-3' and C-5'); 116.15 (C-3); 112.78 (C-4).
Furan-2-carboxylic acid (2,4-dihydroxy-benzylidene)-
hydrazide (9c): Brown powder;Yield 85.29 %; m.p.173-175
°C; IR (cm–1): 3453 ν(O–H); 3117 ν(N–H); 1630 ν(C=O); 1H
NMR (DMSO-d6): 11.95 (1H, s, NH); 11.36 (s, 1H, OH); 9.98
(s, 1H, OH); 8.52 (1H, s, CH=N); 7.93 (s, 1H, H5); 7.27
(d, 1H, H3); 7.31 (d, J = 9.52, 1H, H6'); 6.37 (d, J = 8.08,
1H, H5'); 6.69 (t, J = 1.44, 1H, H4); 6.33 (s, 1H, H3');
13C NMR: 161.31 (C-4'); 159.98 (C-2'); 154.31 (CO); 149.76
(CH); 146.99 (C-2); 146.35 (C-5); 131.80 (C-6'); 115.46 (C-3);
112.67 (C-4); 111.12 (C-1'); 108.31 (C-5'); 103.22 (C-3').
Furan-2-carboxylic acid (2,4-dinitro-benzylidene)-
hydrazide (9d): Yellow powder; Yield 39.54 %; m.p.147-
1
149 °C; IR (cm–1): 3100 ν(N–H); 1660 ν(C=O); H NMR
(DMSO-d6): 12.47 (1H, s, NH); 8.90 (1H, s, CH=N); 8.60
(d.d, J = 8.08, J = 2.2, 1H, H5'); 8.38 (d, J = 8.8, 1H, H6');
8.01 (s, 1H, H5); 7.41 (s, 1H, H3); 7.80 (d, J = 2.2, 1H, H3');
6.75-6.73 (d.d, J = 3.28, J = 2.2, H4).
4-Amino-benzoic acid (1H-pyrrol-2-ylmethylene)-
hydrazide (8b): Brown powder; Yield 94.26 %; m.p.175-
1
176 °C; IR (cm–1): 3225 ν(N–H); 1612 ν(C=O); H NMR
Furan-2-carboxylic acid furan-2-ylmethylene-hydra-
zide (9e): Beige powder; Yield 77.73 %; m.p.110-111 °C; IR
(DMSO-d6): 11.46 (1H, s, NH); 11.25 (NHpyrrole); 7.69 (d, J =
8.56, 2H, H2' and H6'); 6.90 (s, 1H, H5); 6.44 (s, 1H, H3);
6.13 (s, 1H, H4); 6.63 (d, J = 8.56, 2H, H3' and H5'); 5.75 (s,
2H, NH2).
1
(cm–1): 3106 ν(N–H); 1642 ν(C=O); H NMR (DMSO-d6):
11.83 (1H, s, NH); 8.39 (1H, s, CH=N); 7.94 (s, 1H, H5); 7.85
(s, 1H, H5'); 7.27 (s, 1H, H3); 6.93 (d, J = 3.64, 1H, H3');
6.70 (d, J = 1.44, 1H, H4); 6.63 (t, J = 1.48, 1H, H4'); 13C
NMR: 154.67 (CO); 149.94 (C-2'); 147.15 (C-2); 146.37 (C-5);
145.76 (C-5'); 138.15 (CH); 115.58 (C-3); 114.12 (C-3');
112.78 (C-4'); 112.68 (C-4).
2-Hydroxy-benzoic acid (1H-pyrrol-2-ylmethylene)-
hydrazide (8c): m.p. 222-224C; IR (cm–1): 3384 ν(O–H); 3268
ν(N–H); 1618 ν(C=O); 1H NMR (DMSO-d6):12.11 (s, 1H,
OH); 11.59 (2H, s, NH and NHpyrrole); 6.96 (m, 1H, H5); 7.89
(d, J = 8.07, 1H, H6'); 7.44 (t, J = 7.71, 1H, H4'); 6.96-6.91
(m, 2H, H3' and H5'); 6.52 (s, 1H, H3); 6.15 (s, 1H, H4).
2-Amino-benzoic acid (1H-pyrrol-2-ylmethylene)-
hydrazide (8d): m.p. 145-147 °C; 1H NMR (DMSO-d6): 11.47
(1H, s, NH); 11.30 (1H, s, NHpyrrole): 8.80 (1H, s, CH=N); 7.52
(d, 1H, H6'); 7.17 (t, J = 7.71, 1H, H4'); 6.88-6.13 (m, 5H,
H3', H5', H3, H4 andH5); 5.83 (s, 2H, NH2).
4-Methyl-benzenesulfonyl(1H-pyrrol-2-ylmethylene)-
hydrazide (8e): Brown powder,Yield 84.56 %; m.p. 188-189
°C; IR (cm–1): 3171 ν(N–H); 1332-1180 ν(S (=O)2). 1H NMR
(DMSO-d6): 11.27 (1H, s, NH); 10.93 (NHpyrrole); 6.85 (s, 1H,
H5); 6.35 (d, J = 1.11, 1H, H3); 6.08 (t, J = 1.47, 1H, H4);
7.80 (d, J = 8.08, 2H, H2' and H6'); 7.38 (d, J = 8.04, 2H, H3'
and H5'); 2.35 (s, 3H, CH3).
Furan-2-carboxylic acid (5-nitro-furan-2-ylmethylene)-
hydrazide (9f): Yellow powder;Yield 68.22 %; m.p. 149-151
°C; IR (cm–1): 3129 ν(N–H); 1668 ν(C=O);1H NMR (DMSO-
d6): 12.27 (1H, s, NH); 8.39 (CH=N); 7.98 (s, 1H, H5); 7.79
(d, J = 3.68, 1H, H4'); 7.35 (s, 1H, H3); 7.26 (d, J = 4.4, 1H,
H3'); 6.73-6.72 (d.d, J = 3.68, J = 1.48, 1H, H4); 13C NMR:
154.82 (CO); 152.44 (C-5'); 152.24 (C-2'); 146.92 (C-2);
146.63 (C-5); 136.03 (CH); 116.51 (C-3); 115.19 (C-3');
115.80 (C-4'); 112.87 (C-4).
Thiophene-2-carboxylic acid (4-hydroxy-benzylidene)-
hydrazide (10a): Beige powder; Yield 65.52 %; m.p. 278-
282 °C; IR (cm–1): 3654 ν(O–H); 3267 ν(N–H); 1625 ν(C=O);
1H NMR (DMSO-d6):11.69 (1H, s, NH); 9.97 (1H, s, OH);
7.64 (d, J = 8.8, 2H, H2' and H6'); 8.06 (m, 2H, H3 and H5);
7.21 (t, J = 3.64, 1H, H4); 6.86 (d, J = 8.08, 2H, H3' and H5').
Thiophene-2-carboxylic acid (4-nitro-benzylidene)-
hydrazide (10b): Yellow powder; Yield 92.60 %; m.p. 247-
Furan-2-carboxylic acid (4-hydroxy-benzylidene)-
hydrazide (9a): Brown powder,Yield 68.24 %; m.p. 113-121
°C; IR (cm–1): 3394 ν(O–H); 3161 ν(N–H); 1596 ν(C=O); 1H
NMR (DMSO-d6): 11.67 (1H, s, NH); 9.95 (s, 1H, OH); 8.35
(1H, s, CH=N); 7.91 (s, 1H, H5); 7.56 (d, J = 8.8, 2H, H2' and
H6'); 7.27 (s, 1H, H3); 6.85 (d, J = 8.08, 2H, H3' and H5').6.68
(s, 1H, H4); 13C NMR:160.02 (C-4'); 154.62 (CO); 148.80
1
248 °C; IR (cm–1): 3163 ν(N–H); 1648 ν(C=O); H NMR
(DMSO-d6): 12.15 (1H, s, NH); 8.30 (d, J = 8.76, 2H, H3' and
H5'); 8.15 (1H, s, CH=N); 8.06 (m, 4H, H2', H6', H5 and H3);
7.24 (t, J = 3.64, 1H, H4); 13C NMR: 158 (CO); 145.49 (C-4');

3644 Alsaeedi et al.
Asian J. Chem.
142.37 (C-5); 138.33 (CH); 135.73 (C-4); 133.02 (C-2); 130.06
(C-1'); 128.61 (C-2' and C-6'); 127.40 (C-3); 124.66 (C-3' and
C-5').
Thiophene-2-carboxylic acid (5-nitro-furan-2-yl-
methylene)-hydrazide (10f); Yellow powder;Yield 96.79 %;
m.p.259-260 °C; IR (cm–1): 3146 ν(N–H); 1651 ν(C=O); 1H
NMR (DMSO-d6): 12.24 (1H, s, NH); 8.36 (1H, s, CH=N);
7.78 (d, J = 3.68, 1H, H4'); 7.26 (d, J = 4.4, 1H, H3'); 7.24-
7.22 (m, 3H, H3, H4 and H5); 13C NMR: 158.50 (CO); 152.40
(C-5'); 152.24 (C-2'); 138.05 (C-2); 135.71 (C-3); 132.00 (C-
5); 130.29 (C-4); 127.63 (C-4); 115.89 (C-4'); 115.22 (C-3').
Inhibition zone (IZ): Preliminary experiments were
carried out to determine antimicrobial activities of all compounds
in vitro against two Gram-positive bacteria [Staphylococcus
aureus (ATCC 25923); Bacillus subtilis (ATCC 6633)]; three
Gram-negative bacteria [EC: Escherichia coli (ATCC 25922);
ST: Salmonella susi (ATTC 13070); PA: Pseudomonas aeruginosa
(ATCC27853)] and one Fungus [Candida albicans (ATCC
10231)], using wells diffusion method according to National
Committee for Clinical Laboratory Standards. Petri plates
containing 20 mL of nutrient agar. Wells (6 mm in diameter)
were divided into agar and all compound were tested in a
concentration of 100 µg/mL and incubated at 37°C (bacterial
strains) and at 25 °C (fungal strains) for 24 h. The antimicrobial
activities were determined based on measurement of the
diameter of inhibition zone formed around the well using
gentamicin as reference drug. The compounds were dissolved
in DMSO that did not interfere in the microorganism’s growth.
Thiophene-2-carboxylic acid (2,4-dihydroxy-benzyli-
dene)hydrazide (10c): Beige powder; Yield 82.26 %; m.p.
252-253 °C; IR (cm–1): 3682 ν(O–H); 3120 ν(N–H); 1636
ν(C=O); 1H NMR (DMSO-d6): 11.94 (1H, s, NH); 11.30 (s,
1H, OH); 9.97 (s, 1H; OH); 7.89 (d, J = 3.68, 1H, H5); 7.86
(d, J = 5.12, 1H, H3); 7.33 (d, J = 8.76, 1H, H6'); 6.36 (s, 1H,
H3'); 6.34 (d, J = 8.8, 1H, H5').7.22 (t, J = 4.4, 1H, H4);
13C NMR: 161.32 (C-4'); 159.92 (C-2'); 157.81 (CO);
149.23 (C-2); 138.43 (CH); 132.35 (C-3); 131.66 (C-5); 129.42
(C-6'); 128.70 (C-4); 111.15 (C-1'); 108.30 (C-5'); 103.20
(C-3').
Thiophene-2-carboxylic acid (2,4-dinitro-benzyli-
dene)hydrazide (10d): Yellow powder; Yield 96.26 %; m.p.
244-246 °C; IR (cm–1): 3171 ν(N–H); 1645 ν(C=O).1H NMR
(DMSO-d6): 12.43 (1H, s, NH); 8.80 (s, 1H, H3'); 8.79 (1H, s,
CH=N); 8.62 (d, J = 8.8, 1H, H5'); 8.41 (d, J = 8.8. 1H, H6');
8.01 (s, 1H, H5); 7.97 (d, J = 4.4, 1H, H3); 7.25 (t, J = 4.4,
1H, H4).
Thiophene-2-carboxylic acid furan-2-ylmethylene-
hydrazide (10e): Beige powder, Yield 70.02 %; m.p. 163-
1
165 °C; IR (cm–1): 3160 ν(N–H); 1658 ν(C=O); H NMR
(DMSO-d6): 11.82 (1H, s, NH); 8.32 (1H, s, CH=N); 8.08 (s,
1H, H5); 7.99 (s, 1H, H3); 7.87 (s, 1H, H5'); 7.21 (s, 1H, H4);
6.95 (d, J = 2.92, 1H, H3'); 6.64 (s, 1H, H4'); 13C NMR: 158.24
(CO); 149.88 (C-2); 145.80 (C-2'); 145.43 (C-5'); 138.71 (CH);
137.88 (C-3); 134.21 (C-5); 129.50 (C-4); 114.21 (C-3');
112.80 (C-4').
RESULTS AND DISCUSSION
Synthesis of nifuroxazide analogues: Total of 44 hydrazide-
hydrazone derivatives have been synthesized, some among
them were novel and some were new. Nifuroxazide itself (2a)
O
R
1
1
a
b
c
d
e
X
R1
X
CO
CO 4-NH2
CO 2-OH
CO 2-NH2
SO2 CH3
R1
4-OH
O
CO 4-OH
CO 4-NH2
CO 2-OH
CO 2-NH2
SO2 CH3
X
a
b
c
d
e
R1
N2H4
NHNH2
R1
X
Cl
I(a-e)
CHO
O
R2
CHO
2-6
R2
NO2.
X'
7-8
EtOH/ heat
2
X
S
3
4
5
6
H
7
8
CH2OH
Br.
4-C6H4Br.
NH
X
R1
X
R1
O
X'
NHN
R2
NHN
(2a-2e); (3a-3c,3e); (4a-4d);
(5a-5e); (6a-6e)
(7a-7e) -(8b-8e)
Scheme-I: Synthetic pathway for compounds (1a-1d)-(8b-8e)

Vol. 27, No. 10 (2015)
Synthesis and Investigation of Antimicrobial Activity of Some Nifuroxazide Analogues 3645
R
R
O
a
b
c
4-OH
4-NO2
2,4-OH
2,4-NO2
R
H
NHN
d
X
O
a-d
(9a-9d)-(10a-10d)
NHNH2
X
O
X
O
S
9
10
R
O
NHN
R
H
X
e
CHO
O
O
R
f
NO2
(9e-9f) -(10e-10f)
Scheme-II: Synthetic pathway for compounds (9a-9f)-(10a-10f)
TABLE-1
INHIBITION ZONE VALUES (mm) OF COMPOUNDS 1(a-e)-8(a-e), 9(a-f) AND 10(a-f)
Gram-positive
Gram-negative
Fungous
Gram-positive
Gram-negative
Fungous
Compd.
No.
Compd.
No.
6c**
6d**
6e
7a
7b
7c
7d
SA
0
BS
0
EC
0
0
0
10
0
15
22
0
20
15
0
12
0
NT
0
0
0
0
0
NT
10
0
0
12
0
SS
12
12
0
10
20
12
16
15
18
10
15
0
PA
13
15
0
10
0
16
0
15
0
18
15
15
15
NT
12
12
12
17
0
NT
10
10
16
15
10
10
0
CA
0
0
0
0
SA
0
BS
0
EC
0
14
0
0
0
SS
15
14
15
12
14
0
PA
10
15
10
15
15
15
14
20
NT
0
15
NT
0
0
0
CA
0
0
0
0
0
0
0
0
NT
0
0
NT
0
0
0
0
0
0
0
0
0
0
0
0
0
NT
–
1a
1b
1c
1d
1e
2a
2b
2c
2d
2e
3a
3b
3c
3d
3e
0
0
0
0
0
0
0
0
0
0
15
0
0
0
0
10
0
0
0
16
25
15
30
20
0
20
27
20
20
20
0
13
30
15
30
15
0
0
0
NT
0
0
0
0
0
NT
0
0
0
0
0
0
0
0
12
20
NT
0
0
NT
0
0
0
0
13
0
19
0
0
11
10
0
15
23
–
0
0
NT
0
10
NT
0
10
NT
16
15
NT
15
15
12
20
10
13
20
12
14
12
15
15
15
NT
–
7e
8a
8b**
8c
0
0
10
0
0
0
NT
0
NT
0
8d
0
8e
9a**
9b
NT
0
NT
0
NT
15
12
9
0
0
0
0
4a**
4b**
4c
9c
0
0
0
0
0
0
0
13
0
9d**
9e
0
0
0
0
13
0
0
0
15
15
NT
12
12
12
14
20
17
15
4d*
4e
9f
0
0
20
0
26
0
NT
0
NT
0
10a
10b**
10c
10d**
10e
10f
Gen
–
5a**
5b*
5c
0
0
12
0
0
10
0
0
0
10
15
0
11
36
–
0
0
5d**
5e*
6a
0
0
0
0
0
0
25
27
–
22
34
–
0
16
12
15
10
10
0
0
6b*
NT = Not tested; Gentamicin. SA = Staphylococcus aureus (ATCC 25923); BS = Bacillus subtilis (ATCC 6633); EC = Escherichia coli (ATCC
25922); ST = Salmonella susi (ATTC 13070); PA = Pseudomonas aeruginosa (ATCC27853); CA = Candida albicans (ATCC 10231); *Novel
compounds; ** New compounds.
and other representative analogues of the same structural type
[(2a-2e)-(6a-6e)] were synthesized by condensation of 5-
substituted furfural with substituted benzene hydrazide and
benzenesulfonyl hydrazide. Other nifuroxazide analogues
series [(7a-7e)-(8b-8e)] were synthesized by replacing the furan
ring with thiophene and pyrrole. Unfortunately, compounds
(3d, 4e and 8a) have not been synthesized due to inadequacy
of starting materials. Furthermore, other modeling nifuroxazide
structures [9(a-f)-(10a-10f)] were also prepared from the
reaction of furoic hydrazide and the corresponding hydrazide
of thiophene with a variety of aromatic aldehydes, furan-2-
carboxaldehyde and thiophene-2-carboxaldehyde. The

3646 Alsaeedi et al.
Asian J. Chem.
compounds were structurally identified through IR, 1H NMR
and 13C NMR spectra. The synthesis of target compounds is
outlined in Schemes I and II.
Regarding the activity against Candida albicans, all com-
pounds showed no activity with an exception of substituted
nitro furan (2a-2e).
Antimicrobial activity determination: Inhibition zone
(IZ), was determined for all compounds, hydrazide analogues
and hydrazide-hydrazones analogues, by well diffusion
method, using gentamycin as reference drug against two Gram-
positive bacteria [Staphylococcus aureus (ATCC 25923);
Bacillus subtilis (ATCC 6633)]; three Gram-negative bacteria
[EC: Escherichia coli (ATCC 25922); ST: Salmonella susi
(ATTC 13070); PA: Pseudomonas aeruginosa (ATCC27853)]
and one Fungus [Candida albicans (ATCC 10231)].
ACKNOWLEDGEMENTS
This research project was supported by a grant from the
Research Center of the Female Scientific and Medical Colleges,
Deanship of Scientific Research, King Saud University.
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