Synthesis and antibacterial activity of some heterocyclic derivatives of sulfanilamide

Article abstract of DOI:10.4314/bcse.v26i3.15

Considering the promising antimicrobial potential of carbonic anhydrase inhibitors and heterocyclic compounds some heterocyclic derivatives of sulfanilamide (2a-e) were synthesized. The diazotisation of sulfanilamide followed by substitution with ethylace

Full text of DOI:10.4314/bcse.v26i3.15

Bull. Chem. Soc. Ethiop. 2012, 26(3), 455-460.
Printed in Ethiopia
DOI: http://dx.doi.org/10.4314/bcse.v26i3.15
ISSN 1011-3924
 2012 Chemical Society of Ethiopia
SHORT COMMUNICATION
SYNTHESIS AND ANTIBACTERIAL ACTIVITY OF SOME HETEROCYCLIC
DERIVATIVES OF SULFANILAMIDE
B.B. Subudhi* and G. Ghosh
School of Pharmaceutical Sciences, Siksha ‘O’ Anusandhan University,
Po-Ghatikia, At-Kalinga Nagar, Bhubaneshwar-751003, Orissa, India
(Received March 30, 2011; revised February 9, 2012)
ABSTRACT. Considering the promising antimicrobial potential of carbonic anhydrase inhibitors and
heterocyclic compounds some heterocyclic derivatives of sulfanilamide (2a-e) were synthesized. The
diazotisation of sulfanilamide followed by substitution with ethylacetoacetate and further condensation yielded
compounds 2a-c. Schiff base of sulfanilamide with salicylaldehyde on reaction with thioglycollic acid and
chloroacetyl chloride resulted in compound 2d-e. The susceptibility of Staphylococcus aureus, Enterococcus
faecalis, Escherichia coli and Pseudomonas aeruginosa to the title compounds (300 µg/disc) was investigated
and compared to that of nitrofurantoin (300 µg/disc) and ciprofloxacin (25 µg/disc). The title compounds showed
good antimicrobial activity.
KEY WORDS: Carbonic anhydrase, Sulfanilamide, Heterocyclic compounds, Antimicrobial activity
INTRODUCTION
The field of research on development of carbonic anhydrase inhibitor based antimicrobials has
shown promising results due to presence of carbonic anhydrases in a multitude of bacteria and
protozoa [1-3]. Sulfanilamide, a prototype of carbonic anhydrase inhibitor has good potential
for antibacterial action [4-5]. Conjugations of heterocyclic groups reportedly enhance
antibacterial action of the original compound [6]. Besides derivatives of azetidinone,
thiazolidinone [7], oxazoles [8] and imidazoles [9] are widely reported with antibacterial action.
It is thus envisageable that conjugation of heterocyclic compounds with sulfanilamide will be
able to enhance the antibacterial action of sulfanilamide leading to novel types of
pharmacological agents useful in the fight against infections. Keeping this in view, we have
attempted synthesis of heterocyclic derivatives of sulfanilamide, and investigated the in vitro
susceptibility of two gram-positive bacteria (S. aureus, E. faecalis) and two gram-negative
bacteria (E. coli and P. aeruginosa) to them.
EXPERIMENTAL
The synthesized compounds 2a-e (Scheme 1) were purified with repeated washing and
recrystallisation from different solvents. Purity of compounds was checked by TLC using
chloroform: methanol: DMF (100+10+05 v/v) as developing solvents and iodine as visualizing
agent. Melting points were determined in open capillary tubes (Sisco) and were uncorrected.
1
Infrared spectra were recorded on Shimadzu-8400S spectrophotometer using KBr powder. H
NMR spectra were recorded in CDCl3 on a Bruker DRX-300 NMR spectrophotometer (300
MHz) using TMS as internal standard. The CHN elemental analysis was carried out using
EURO-EA elemental analyzer.
__________
*Corresponding author. E-mail: bharatbhusans@gmail.com

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B.B. Subudhi and G. Ghosh
a. sodium nitrite, b. ethylacetoacetate, c. phenyl hydrazine, d. hydrazine hydrate, e. hydroxyl-
amine hydrochloride, f. Salycylaldehye, g. chloroacetyl chloride, h. thioglycollic acid.
Scheme 1. Synthesis of heterocyclic derivatives of sulfanilamide.
Synthesis of compound 1 and 2a-e were done as per the reported method [7-8] with little
modification.
Synthesis of ethyl-3-oxo-2-(2-(4-sulfamoylphenyl)hydrazono)butanoate (1). Sulfanilamide (0.01
mol) was taken as the starting material in a mixture of HCl (8 mL) and water (6 mL). It was
o
cooled to 0 C in an ice bath and a cold aqueous solution of sodium nitrite (0.03 mol) was
added. The diazonium salt solution was filtered directly into a cold solution of ethylacetoacetate
(0.01 mol) and sodium acetate (0.122 mol) in ethanol (50 mL). The resulting solid was washed
with water and recrystallised from alcohol to yield ethyl-3-oxo-2-(2-(4-sulfamoylphenyl)
hydrazono) butanoate (1).
Synthesis of 4-(2-(3-methyl-5-oxo-1H-pyrazol-4(5H)-ylidine) hydrazinyl) benzene sulfonamide
(2a). Compound 1 (0.002 mol) was dissolved in glacial acetic acid (20 mL) and phenyl
hydrazine (0.002 mol). The mixture was refluxed for 4 h, cooled and allowed to stand overnight.
The product so formed was filtered, dried and recrystallised from aqueous ethanol to produce 4-
(2-(3-methyl-5-oxo-1H-pyrazol-4(5H)-ylidine) hydrazinyl) benzene sulfonamide. The
compound 4-(2-(3-methyl-5-oxo-1H-pyrazol-phenyl ylidine) hydrazinyl) benzene sulfonamide
(2b) was prepared using hydrazine hydrate.
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457
Synthesis of 4-(2-(3-methyl-5-oxoisoxazol-4(5H)-ylidine) hydrazinyl)benzene sulfonamide (2c).
To the compound 1 (0.001 mol) in ethanol a solution of sodium acetate (1 g) and hydroxylamine
hydrochloride (0.001 mol) in water was added and the solution was refluxed for 4 h. On cooling
the solid obtained was recrystallised from ethanol to yield 4-(2-(3-methyl-5-oxoisoxazol-4(5H)-
ylidine) hydrazinyl) benzene sulfonamide (2c).
Synthesis of 4-(2-(2-hydroxyphenyl)-4-oxothiazolidin-3-yl) benzene sulfonamide (2d). Schiff
base of sulfanilamide with salicylaldehyde (2) was prepared by laboratory method. It (0.01 mol)
was refluxed with thioglycollic acid (0.01 mol) in presence of anhydrous aluminium chloride
(0.05 g) at 120 ºC for 12 h. The reaction mixture was then cooled and triturated with an excess
of 10% sodium bicarbonate solution. The product formed was filtered, washed repeatedly with
water, dried and recrystallised from aqueous ethanol to give 4-(2-(2-hydroxyphenyl)-4-
oxothiazolidin-3-yl)benzene sulfonamide (2d).
Synthesis of 4-(3-chloro-2-(2-hydroxyphenyl)-4-oxoazetidin-1-yl) benzene sulfonamide (2e).
The Schiff base (0.01 mol) was dissolved in DMF (40 mL) and triethylamine (2.8 mL) was
added to it. Chloroacetylchloride (0.01 mol) was added drop wise over a period of 30 min and
then refluxed for 5 h. The reaction mixture was concentrated to half of its initial volume and
then poured on to crushed ice. The product obtained was filtered, washed, dried and
recrystallised from ethanol to yield 4-(3-chloro-2-(2-hydroxyphenyl)-4-oxoazetidin-1-yl)
benzene sulfonamide.
Ethyl-3-oxo-2-(2-(4-sulfamoylphenyl)hydrazono)butanoate (1). Yellow color solid. Yield 54%.
m.p. 145 ºC, IR (cm-1, KBr): 3201.12 (N-H str.), 3011.42 (Ar-H str.), 1712.12 (C=O str), 1631.2
(C=N str), 1341.49 [(S=O)2 asymmetric str], 1148.56 [(S=O)2 symmetric str]. Mol. wt. anal.
found = 312.4. Cacld. for C12H15O5N3S = 313.
4-(2 –Hydroxy pheyl)imno benzenesulfonamide (2). Yellow color solid. Yield 75%. m.p. 212
ºC, IR (cm-1, KBr): 3412.21 (O-H str.), 3223.65(N-H str.), 3035.97(Ar-H str.), 1652.21(C=N
1
str), 1344.53 [(S=O)2 asymmetric str], 1155.96 [(S=O)2 symmetric str], 603.89 (C-S str). H
NMR (δppm, CDCl3): 6.9-7.89 (m, Ar-H), 2 (s, 2H, -NH2), 5.1 (s, 1H, - OH). Mol. wt. anal.
found = 275.7. Cacld. for C13H12O3N2S = 276.
4-(2-(3-Methyl-5-oxo-1H-pyrazol-4(5H)-ylidine) hydrazinyl) benzene sulfonamide (2a). Red
color solid. Yield 58 %. m.p. 238 ºC. IR (cm-1, KBr): 3210.54 (N-H str.), 3015.23 (Ar-H str.),
1703.3 (C=O str), 1638.21(C=N str), 1462.12 (C=C str ), 1344.23 [(S=O) 2 asymmetric str],
1159.26 [(S=O) 2 symmetric str], 607.22 (C-S str). 1H NMR (δppm, CDCl3): 6.8-7.6 (m, 4H,
Ar-H), 2 (s, 2H, -NH2), 2.33 (s, 3H, -CH3). Anal. found: C, 53.5;H, 4.87; N, 18.98%. Cacld. for
C16H15O3N5S: C, 53.78; H, 4.2; N, 19.6%.. Mol. wt. anal. found = 356.7. Cacld. for
C16H15O3N5S = 357.
4-(2-(3-Methyl-5-oxo-1H-pyrazol-phenyl-ylidine) hydrazinyl)benzene sulfonamide (2b). Yellow
color solid. Yield 56 %. m.p. 232 ºC. IR (cm-1, KBr): 3210.39 (N-H str.), 3023.52 (Ar-H str.),
1703.89(C=O str), 1623.72(C=N str), 1456.62 (C=C str ), 1341.43 [(S=O) 2 asymmetric str],
1155.96 [(S=O) 2 symmetric str], 604.32 (C-S str). 1H NMR (δppm, CDCl3): 6.8-7.9 (m, 4H,
Ar-H), 2 (s, 2H, -NH2), 2.31 (s, 3H, -CH3). Mol. wt. anal. found = 280.29. Cacld. for
C10H11O3N5S = 281.
4-(2-(3-Methyl-5-oxoisoxazol-4(5H)-ylidine) hydrazinyl) benzene sulfonamide (2c). Cream
color solid. Yield 62 %. m.p. 201 ºC. IR (cm-1, KBr): 3215.45 (N-H str.), 3023.33 (Ar-H str.),
1730.21 (C=O str), 1651.21(C=N str), 1462.09 (C=C str ), 1344.43 [(S=O) 2 asymmetric str],
Bull. Chem. Soc. Ethiop. 2012, 26(3)

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B.B. Subudhi and G. Ghosh
1
1159.26 [(S=O) 2 symmetric str], 603.74 (C-S str). H NMR (δppm, CDCl3): 6.9-7.6 (m, 4H,
Ar-H), 2.2 (s, 2H, -NH2), 3.1 (s, 3H, - CH3). Anal. found: C,43.1;H, 3.4; N, 19.3%. Cacld. for
C10H10O4N4S: C, 42.55; H, 3.54; N, 19.85%. Mol. wt. anal. found = 282.4. Cacld. for
C10H10O4N4S = 282.
4-(2-(2-Hydroxyphenyl)-4-oxothiazolidin-3-yl) benzene sulfonamide (2d). Brown color solid.
Yield 54 %. m.p. 320 ºC. IR (cm-1, KBr): 3439.86(O-H str.), 3221.39 (N-H str.), 3022.43 (Ar-H
str.), 1712.87(C=O str), 1633.54(C=N str), 1344.43 [(S=O) 2 asymmetric str], 1155.32 [(S=O) 2
symmetric str], 607.82 (C-S str). 1H NMR (δppm, CDCl3): 6.7-7.9 (m, Ar-H), 6.3(s, 1H-
OH),5.1 (s,1H-CH-), 4.1 2 (s, 2H, -CH2-), 2. 1(s, 2H, -NH2). Anal. found: C, 51.2;H, 4.7; N,
8.11%. Cacld. for C15H14O4N2S2: C, 51.42; H, 4; N, 8.2%. Mol.wt. anal. found = 349.61. Cacld.
for C15H14O4N2S2 = 350.
4-(3-Chloro-2-(2-hydroxyphenyl)-4-oxoazetidin-1-yl) benzene sulfonamide (2e). Brown color
solid. Yield 48 %. m.p. 264 ºC. IR (cm-1, KBr): 3431.55(O-H str.), 3232.11 (N-H str.), 3041.62
(Ar-H str.), 1694.11(C=O str), 1334.74 [(S=O) 2 asymmetric str], 1163.52 [(S=O) 2 symmetric
str], 608.78 (C-S str). 1H NMR (δppm, CDCl3): 6.9-7.9 (m, Ar-H), 5.8 (s, 1H-OH), 5.16 (s,1H-
CH-), 5.42 (s, 1H, -CH-), 2 (s, 2H, -NH2). Mol. wt. anal. found = 352.94. Cacld. for
C15H13ClN2O4S = 352.5.
RESULTS AND DISCUSSION
The physico-chemical data were used to characterize the compounds. The synthesized
compounds exhibited characteristic IR (KBr, ν cm-1) peaks in the region of 3319.60 (N-H str),
1680.05 (C=O str), 1344.43 [(S=O) 2 asymmetric str], 1159.26 [(S=O) 2 symmetric str], 603.74
(C-S str) 3057.27 [C-H str (aromatic)], 1663 (C=N str) and 1433.16 (C=C str). The title
1
compounds exhibited characteristic H NMR peaks. The molecular weights determined by
Rast’s procedure and the elemental proportions of compounds were close to the theoretical
values.
For the in vitro screening pure strains were obtained from Post Graduate Department of
Microbiology, Orissa University of Agricultural Technology, Bhubaneswar, India. The
organisms were identified [7] and screened using disc diffusion method [11-12]. The
compounds were dissolved in dimethyl formamide (6%), which was previously tested for
antibacterial activity against all test bacteria and found to have no antibacterial activity. A
solution of concentration 30 mg/mL was made for each test compounds and finally sterilized by
filtration using 0.45 µm millipore filters. The sterile discs (Hi-media, 6mm) were impregnated
with 10 µL of the test solutions (300 µg/disc) and placed in inoculated agar. The density of the
bacterial suspension was standardized by using McFarland standard method [8-9].
Nitrofurantoin (300 µg/disc) and ciprofloxacin (25 µg/disc) were used as standard drugs. The
o
control was prepared using dimethyl fomamide. The inoculated plates were incubated at 37 C
for 24 h. The antibacterial activity of test compounds against the bacterial strains is given in
Table 1 as zone of inhibition (mm).
The control did not show any zone of inhibition. Compounds 2a-e exhibited significant (p <
0.001) antimicrobial action compared to control. Compound 2d showed highest zones of
inhibition against E. coli and P. aureginosa. Activity was better for 2b, 2c and 2d, against S.
aureus. Compared to nitrofurantoin, most of the compounds exhibited comparable or better
antimicrobial activity against all the strains (Table 1). The zone of inhibition against E. faecalis
was highest for compound 2c.All the compounds exhibited better zones of inhibition than that
of sulfanilamide against all microbial strains. Analysis of structural features reveals that
substitution with heterocyclic group has increased the antimicrobial potential of sulfanilamide
and the increment was more pronounced for the thiazolidinone derivative.
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Short Communication
Table 1. Antimicrobial activity of test compounds.
459
Compound
Zones of inhibition (mm)
µg/disc
E. coli
P. aeruginosa
S. aureus
E. faecalis
Sulfanilamide
300
13.4±0.55
12.3±1.21
11±2.1
10.5±1.4
17±0.47
19±1.45
23.4±2.16
2a
2b
2c
300
300
300
17.2±1.41
17.6±0.34
18.4±1.06
16.45±0.32
18.2±0.43
17.7±2.07
14.4±2.14
17.1±1.52
18.4±1.34
2d
300
21.7±0.84
22.4±1.41
17.6±1.55
16.3±1.21
2e
Control
300
-
14.7±2.15
-
16.1±0.74
-
14.8±1.53
-
19.7±0.87
-
Ciprofloxacin
Nitofurantoin
25
300
28±0.15
18.4±0.45
26.4±0.45
12.6±0.65
25.3±0.15
11.8±0.75
26.4±0.45
15.3±0.37
CONCLUSIONS
The successful syntheses of some heterocyclic derivatives of sulfanilamide were reported. It is
noticeable that derivatisation of sulfanilamide, a carbonic ahydrase inhibitor potentiates its
antimicrobial action. From the results of the antimicrobial screening, it can be concluded that
the new synthesized compounds (2b, 2c and 2d) have good potential for antimicrobial property
and hence can be used as leads for further development.
ACKNOWLEDGEMENTS
The authors wish to extend thanks to HOD, Post Graduate Department of Microbiology, Orissa
University of Agricultural Technology, Bhubaneswar for providing the microbial strains.
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