Naresh K et al., PharmaScient, Volume 1, Issue 1, 2012; 1-4.
www.pharmascient.com 1
Evaluation of Anti-Bacterial and Anti-Fungal of Novel Thiophene Derivatives
Madhukar. A, Anjali shah M, Sandeep Kumar C, Swetha M, Bharath Kumar B, Naresh K* Department of Pharmaceutical Chemistry, St.Mary’s College of Pharmacy, Secunderabad. A.P. – INDIA. *[email protected]
ABSTRACT
Thiophene nucleus has been established as the potential entity in the largely growing chemical world of
heterocyclic compounds possessing promising pharmacological characteristics. The similar compounds
synthesized through different routes bear variable magnitudes of biological activities. In the same way
compounds with azitidinone moiety possess a varied number of biological activities. In view of this it is
worthwhile to prepare different thiophene derivatives that bear an azitidinone moiety at C-2. Different 2-amino
thiophene-3-carboxylic acid ethyl esters were prepared by using Gewald’s reaction. 2-amino thiophene 3-caboxy
hydrazides were prepared by condensing Phenyl hydrazine with 2-amino thiophene-3-carboxylic acid ethyl
esters. From 2-amino thiophene 3-caboxy hydrazides different Schiff’s bases were prepared by reacting with
various aromatic aldehydes (viz. Benzaldehyde, Cinnamaldehyde, Para amino Dimethyl Benzaldehyde, Indole-3-
caboxaldehyde). Finally the Schiff’s bases thus obtained were treated with chloroacetylchloride in presence of tri-
ethyl amine to afford the title compounds. The title compounds were subjected to evaluate for their anti-
bacterial and anti-fungal activities.
Key words: Thiophene, azitidinone, anti-bacterial activity and anti-fungal activity.
INTRODUCTION
Thiophene nucleus is a biologically important
heterocyclic moiety and attracting attention in
chemistry research due to its diverse range of
biological activities. An intensive literature review
on thiophene, azitidinone and their derivatives
revealed that they were found to possesses different
biological activities such as antibacterial1,
mycolytic1 antimicrobial activity2,3, anti-mitotic4,
antidepressant activity5. Azetidinone derivatives
which contain β-lactam ring in their structure show
potent anti-cunvulsant6, atni-tubercular7, anti-
inflammatory and anti-tumor activities.8 In view of
the biological importance and the past research on
the thiophene, azitidinone and their derivatives; it is
worthwhile to synthesize some novel azatidinone
incorporated thiophene derivatives. The synthesis of
title compounds was achieved by a systematic
approach is outlined in the Scheme-I.
MATERIALS AND METHODS
Melting points of all the compounds were
determined in open capillaries using Toshniwal and
Cintex melting point apparatus and are uncorrected.
IR spectra of the compounds were recorded on
SCHIMADZU FT-IR Spectrophotometer by using KBr
discs. Progress of the each reaction in the present
investigation was monitored by TLC using E-Merck
0.25mm silica gel plates.
EXPERIMENTAL METHODS
Synthesis of 2-amino-4,5-sustituted thiophene-3-
carboxylate (Ib&Ic): An equimolar mixture of
sulphur (0.1moles), ethyl cyano acetate (0.1mole)
and ketone (cyclohexanone for I and buta-2-one for
II), (0.1mole), were taken in a conical flask
containing 10 to 15mL of ethanol. The mixture was
stirred for 5minutes and morpholine (0.1mole) was
slowly added with stirring for 15minutes. This was
irradiated at 180W for four minutes and it was
cooled to room temperature and kept in refrigerator
Naresh K et al., PharmaScient, Volume 1, Issue 1, 2012; 1-4.
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overnight. The crystals thus obtained were collected
by filtration under reduced pressure. The collected
crystals were washed with cold carbinol and
recrystallised using ethanol.
Synthesis of 4,5-substituted 2-amino thiophene-3-
carboxyphenyl hydrazides (IIb & IIc):
An equimolar mixture of phenyl hydrazine and
respective 2-amino-4, 5-sustituted thiophene-3-
carboxylate (Ib&Ic) were taken and dissolved in
20mL of ethanol and irradiated at 450W for
3minutes. The crystals were collected under
reduced pressure and washed with cold carbinol
and recrystallised using ethanol.
Synthesis of 2[(aryl)methylene amino] 4,5-
substituted thiophene-3-carboxyhydrazides (IIIa-
h):
Equimolar quantities of compound IIb & IIc were
taken separately and dissolved in required amount
of ethanol and then acidified with glacial acetic acid.
The reaction mixture further treated with various
Aromatic aldehydes (0.36gms) and irradiated at
350W for three minutes, it was allowed to cool to
room temperature. The crystals were collected by
filtration under reduced pressure and recrystallized
using ethanol.
Synthesis of 2[(3-chloro, 4-aryl azetidine-2-one)]-
4,5-substituted thiophene-3-carboxy hydrazide:
The products of the previous step 2[(aryl)methylene
amino] 4,5-substituted thiophene-3-
carboxyhydrazides (IIIa-h) were dissolved in benzene
separately. An equimolar mixture of
chloroacetylchloride and tri ethylamine was added
to above solution by keeping the conical flask in an
Ice bath. Later it was allowed to cool to room
temperature and irradiated at 600W for 4minutes.
The reaction mixture was poured on to 200gm of
crushed ice. The crude compound thus obtained was
collected by filtration and dried. All the final
compounds obtained were purified by
recrystallisation.
Scheme I
+ H2CS +
ETHANOL,MORPHOLINE
180W, 4 MIN
CN
COOC2H5
R1 C
OH2C R2
SNH2
R2
CR1
O
OC2H5
PHENYLHYDRAZINE,
ETHANOL
300W,3MIN
Ia & Ib
S
R1
R2 NH2
C
OHN
HN
S
R1
R2
N
C
OHN
HN
S
R1
R2
C
OHN
HN
HC Ar
NHC Ar
O Cl
Glacial Acetic acid
Ar-CHO
Chloroacetyl Chloride,TEA
IIa & IIb
IIIa-hIVa-h
[R1
= R2
= CH3]
[R1= R2 = -(CH2)4-]Ia, IIa, IIIa-d, IVa-dIb, IIb, IIIe-h, IVe-h
Ar = Phenyl, Cinnamyl, N,N Dimethyl amino Benzyl Indole-3-yl
Naresh K et al., PharmaScient, Volume 1, Issue 1, 2012; 1-4.
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EXPERIMENTAL SECTION Antibacterial activity: All the synthesized
compounds were screened for their possible
antibacterial activity by disc diffusion
technique9,10,11 against Escheresia coli,
Pseudomonas aeruginosa bacterial strains. The test
compounds and standard were dissolved in DMSO,
solvent and growth controls were kept for
comparison. The zone of inhibition (mm) were
measured after incubating the petri plates for 24h
at 370C and the results are given in (Table 1)
Antifungal activity: The synthesized compounds
were also screened for antifungal activity9, 10, 11
against fungal strains Sachharomyces cerevisiae,
Candida albicans. The diameter of zone of
inhibition was noted. Fluconazole was used as
standard to compare the activity of title
compounds. The results are given in (Table 2)
Table 1: Physical data table
Compound Molecular formula Melting point Yield (%) Molecular weight Ic C11H15NO2S 108-1100C 75.8 225.31 Ib C9H13NO2S 92-960C 75 199.27 IIb C13H15N3OS 125-1300C 75 261.34 IIc C15H7N3OS 182-1850C 65 287.38 IIIa C22H21N3OS 70-720C 73 375.49 IIIb C24H26N4OS 75-760C 70 418.55 IIIc C24H23N3OS 70-730C 71 401.52 IIId C24H22N4OS 90-960C 76 414.52 IIIe C20H19N3OS 73-780C 78 349.45 IIIf C22H24N4OS 76-800C 76 392.52 IIIg C22H21N3OS 90-950C 69 375.49 IIIh C22H20N4OS 110-1150C 74 388.49 IVa C24H22N3O2S 90-950C 76 451.97 IVb C26H27ClN4O2S 94-1000C 74 495.04 IVc C26H27ClN3O2S 101-1030C 76 478.01 IVd C26H23ClN4O2S 104-1100C 74 491.00 IVe C22H20ClN3O2S 120-1280C 73 425.93 IVf C24H25ClN4O2S 110-1130C 72 469.00 IVg C24H22ClN3O2S 112-1160C 72 451.97 IVh C24H21ClN4O2S 110-1150C 78 464.97
Table 2: Antibacterial and Anti-fungal data of title compounds
Compound (1000µg/mL)
Zone of inhibition(in mm) E.Coli P.aeruginosa C. albicans S. cerevisiae
IVa 12 11 13 10 IVb 12 12 12 11 IVd 16 15 16 17 IVe 12 11 12 11 IVf 17 16 15 16 IVg 11 13 11 12 IVh 15 16 17 16
Standard(100 µg/mL) 22 23 24 21
Naresh K et al., PharmaScient, Volume 1, Issue 1, 2012; 1-4.
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RESULTS AND DISCUSSION
Synthesis of seven different 2[(3-chloro, 4-aryl
azetidine-2-one)]-4, 5-substituted thiophene-3-
carboxy hydrazide was carried out by employing
microwave irradiation method by following a
systematic approach, initially the starting material
2-amino thiophene- 3-carboxylate ethyl esters were
(Ia & I b) obtained by the reaction of
ethylactoacetate with a ketone and elemental
sulphur in presence of morpholine. In the following
step compounds (Ia & Ib) were further condensed
with phenyl hydrazine to afford respective2- amino
thiophene-3-carboxyhydrazides (IIa & IIb).
The 2- amino group of resulted compounds was
condensed with a variety of aromatic aldehyde to
achieve respective schiff’s bases. Formation of the
schff’s base was confirmed by the disappearance of
-NH2 peak in the IR spectra that was observed in the
2-amino thiophene carboxy hydrazides. Finally all
the schiff’s base were again condensed with
chloroacetyl chloride in TEA afford the respective
2[(3-chloro, 4-aryl azetidine-2-one)]-4, 5-
substituted thiophene-3-carboxy hydrazide.
The results of in-vitro antibacterial activity revealed
that among the all tested compounds, compounds
IVd, IVf and IVh showed moderate antibacterial
activity. The antifungal data of title compounds
revealed that no compound is as good as standard
drug fluconazole against tested fungal strains.
However compounds IVd, IVf and IVh showed
moderate antifungal activity.
CONCLUSION
Seven thiophene derivatives have successfully been
synthesized by employing microwave irradiation
from thiophene -3- carboxylate. Azitidinone moiety
was incorporated into the thiophene moiety at
second position. At the third carbon carbonyl group
was hydrazinated. All the final compounds and
compound IIIa-h (data not shown) were screened for
their antimicrobial activity on selected strains of
bacteria and fungi. The results demonstrated the
importance of azitidinone moiety and its effect of
incorporation on its antimicrobial activity. Anti
fungal and antibacterial activity has been increased
in all the tested and compounds IVd, IVf and IVh
showed good activity among the tested compounds.
Hence this series with a substitution on azitidinone
could be considered as a lead molecule for the
design of future antimicrobial agents.
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