Naresh K et al., PharmaScient, Volume 1, Issue 1, 2012; 1-4.

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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. *naresh4nani@gmail.com

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

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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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