Design, Synthesis, and Evaluation of Thiazolidinone Derivatives as Antimicrobial and Anti-viral Agents

Article abstract of DOI:10.1111/j.1747-0285.2011.01149.x

A series of 1,3-thiazolidin-4-one derivatives were prepared by the reaction of respective aromatic amine, aromatic aldehyde, and thioglycolic acid in dry benzene/toluene. The newly synthesized compounds were characterized on the basis of elemental analysi

Full text of DOI:10.1111/j.1747-0285.2011.01149.x

ª 2011 John Wiley & Sons A/S
doi: 10.1111/j.1747-0285.2011.01149.x
Chem Biol Drug Des 2011; 78: 464–470
Research Letter
Design, Synthesis, and Evaluation of
Thiazolidinone Derivatives as Antimicrobial
and Anti-viral Agents
Veerasamy Ravichandran1,2,*, Abhishek
Jain2, Krishnan S. Kumar3, Harish Rajak4
and Ram K. Agrawal2
Thiazolidin-4-ones have been reported to posses a wide range of
biological activities including antibacterial (1), antitubercular (2),
antitumor (3), antihistaminic (4), anti-inflammatory (5), and anticon-
vulsant activity (6). Several 2,3-diaryl-1,3-thiazolidin-4-ones have
proved to be particularly effective against non-nucleoside HIV
reverse transcriptase inhibitors (NNRTIs) (7). These compounds may
be considered as an 'open compound model' (8) of previously
described 1H,3H-thiazolo[3,4-a]benzimidazoles (TBZs) (9) because
they contain necessary pharmacophoric elements of those HIV-1
NNRTIs, namely a benzene-fused ring, an aryl group at C-1 and
the nitrogen atom of the thiazole nucleus. Structure activity rela-
tionship (SAR) studies have shown that the anti-HIV activity
strongly depends on the nature of substituents at C-2 and N-3 of
the thiazolidinone ring. It has been demonstrated that a high anti-
viral activity was associated with the presence of a 2,6-dihalo-
substituted phenyl ring at C-2 and pyridin-2-yl or pyrimidin-2-yl rings
at N-3 (8,10).
1Faculty of Pharmacy, AIMST University, Semeling – 08100, Kedah,
Malaysia
2Department of Pharmaceutical Sciences, Dr. H. S. Gour
Vishwavidyalaya, Sagar (MP), India
3Medicinal Chemistry Research Laboratory, KMCH College of
Pharmacy, Coimbatore, India
4SLT Institute of Pharmaceutical Sciences, Guru Ghasidas University,
Bilaspur (CG), India
*Corresponding author: Veerasamy Ravichandran,
phravi75@rediffmail.com
A series of 1,3-thiazolidin-4-one derivatives were
prepared by the reaction of respective aromatic
amine, aromatic aldehyde, and thioglycolic acid in
dry benzene/toluene. The newly synthesized com-
pounds were characterized on the basis of elemen-
tal analysis, IR, 1HNMR, and mass spectra. The
newly synthesized final compounds were evalu-
ated for their in vitro antibacterial, antifungal, and
anti-viral activities. Preliminary results indicated
that some of the compounds demonstrated anti-
bacterial activity in the range of 7–13 lg/mL, anti-
fungal activity in the range of 13–17 lg/mL,
comparable with the standard drugs, ciprofloxacin
and fluconazole. Structure–activity relationship
studies revealed that the nature of the substitu-
ents at the 2 and 3 positions of the thiazolidinone
nucleus had a significant impact on the in vitro
antimicrobial and anti-viral activity of these clas-
ses of agents.
In 2002, the synthesis of diastereoisomers of trans- and cis-5-
methyl-2,3-diaryl-1,3-thizolidin-4-ones from 2,6-dihalobenzaldehyde,
heteroaromatic amine, and racemic 2-mercaptopropionic acid was
reported and the author concluded that stereochemistry has not
influenced the anti-HIV activity of the compounds. Surprisingly, the
stereoselectivity of thiazolidin-4-ones has not yet been profoundly
studied (11). Rao et al. (12) synthesized and evaluated anti-HIV
activity of new 2,3-diaryl-1,3-thiazolidin-4-ones and their results of
the in vitro tests showed that some of them were highly effective
inhibitors of HIV-1 replication at 10–40 nM concentrations with min-
imal cytotoxicity.
In 2007, the anti-HIV activity of 2-aryl-3-heteroaryl-1,3-thiazolidin-4-
ones was studied and concluded when one of their synthesized
compound was found to be the most promising compound and
active against HIV-1 replication exhibiting EC50 at 0.26 lM with
minimal toxicity in MT-4 cells as compared to 0.35 lM for thiazo-
benzimidazole (TBZ) (13). In 2007 and 2009, synthesis of a series of
novel thiazolidin-4-ones bearing a lipophilic adamantyl substituent
at position 2 or 3 was performed by Balzarini et al. (14,15) and
reported that majority of the compounds showed a modest anti-
HIV-1 activity, whereas 2-adamantan-1-yl-3-(4,6-dimethylpyrimidin-
2-yl)-thiazolidin-4-one was endowed with a remarkable anti-viral
potency (EC50 = 0.67 lM).
Key words: antibacterial, antifungal, anti-viral, Schiff's reaction,
thiazolidinones
Received 23 March 2010, revised 7 March 2011 and accepted for publi-
cation 17 May 2011
Viral infections caused by the rapid emergence of anti-viral drug-
resistant strains have become a serious globe threat and this has fos-
tered the search for new anti-viral agents directed against unexplored
drug targets. Various nucleoside analogs (currently used as anti-viral
agents) often inhibit viral polymerases enzyme. However, only few
non-nucleoside anti-viral agents are currently used in the market.
Three 3-substituted-2-adamantyl-4-thiazolidinones were screened
against twelve bacterial strains, and the minimal inhibitory concen-
464

Design, Synthesis, Evaluation of Thiazolidinone Derivatives
trations (MIC, 125 mg/mL) indicated that these compounds were
visualized by exposing them to iodine vapor). After completion of
the reaction, the reaction mixture was concentrated to dryness
under reduced pressure and the residue was taken up in ethyl ace-
tate. The organic layer was successively washed with 5% aqueous
citric acid, water, 5% sodium hydrogen carbonate, and then finally
with brine. The organic layer was dried over sodium sulfate and fil-
tered, and solvent was removed under reduced pressure to obtain
crude (solid or oily) product. The oily residue was made solid by
treatment with a mixture of ethanol and diethyl ether. All the com-
pounds were recrystallized from ethanol (Table 1). Each of the syn-
thesized compounds was highly soluble in DMSO, soluble in DMF,
CHCl3, ethanol and methanol, and sparingly soluble in water. The
structures of synthesized compounds were elucidated by the means
of FTIR, 1HNMR, FAB-MS, and elemental analyses. The results of
elemental analyses for C, H, and N of all the synthesized com-
pounds were within €0.4% of the theoretical values.
poor antibacterial agents (16). Antibacterial activity of some new
2,3-diaryl-1,3-thiazolidin-4-ones were reported in 2006 (17).
Prompted by the earlier observations, we designed and synthesized
a series of novel thiazolidin-4-one derivatives (1–10) bearing the
different aryl, heteroaryl substituent at position 2, and several sub-
stituents on the nitrogen atom in the thiazolidine ring.
Materials and Methods
Chemistry
Melting points were determined using an open-ended capillary
method and are uncorrected. The reaction was monitored by TLC. UV/
VIS spectra were taken in a Shimadzu UV/VIS 1700 spectrophotometer
(Kyoto, Japan). FT-IR was recorded on a Jasco FT-IR spectrophotome-
ter (Tokyo, Japan), and 1HNMR spectra were recorded at 300 MHz on
a Bruker FT-NMR spectrometer (Ettlingen, Germany) and mass spectra
on a Varian Atlas CH-7 mass spectrometer (Tokyo, Japan) at 70 eV.
The elemental analysis was obtained on a Vario-EL instrument.
2-(4-methoxyphenyl)-3-(4-sulphonamidophenyl)
thiazolidin-4-one [1]
Yield: 0.73 g (40.22%); IR (KBr, in cm)1): 3422 (N-H str. for -NH2),
1686.30 (C=O str.), 1490.32, 1358, 1275, 1152.26 (S=O str. for SO2);
1HNMR (CDCl3, d in ppm): 3.72 (s, 3H, OCH3), 3.89 (d, 1H,
J = 15.7 Hz, 5-HA), 4.15 (dd, 1H, J = 15.7 and 1.9 Hz, 5-HB), 5.94 (s,
1H, H-2), 6.93–8.01 (m, 8H, ArH), 10.02 (br s, 2H, SO2NH2); Mass:
365 (M+H)+; Anal. Cal. C, 52.73; H, 4.43; N, 7.69; Found C, 52.78;
H, 4.39; N, 7.66.
General procedure for synthesis of 1,3-
thiazolidin-4-ones
We followed the method reported by Rawal et al. (13) with slight
modification to synthesize 1,3-thiazolidin-4-one derivatives. The
appropriate (hetero) aromatic amine (sulphanilamide, para chloro
aniline, ortho amino pyridine, 5-chloro-2-amino pyridine, 2-amino-6-
methyl pyridine, 2-amino-4,6-dimethyl pyridine, 2-amino-6-methyl-
pyridine, phenyl ethyl amine) (1.0 mmol) and appropriate (hetero)
aromatic aldehyde (para methoxy benzaldehyde, para nitro benzalde-
hyde, 2,5-dimethoxy benzaldehyde, pyridine-2-aldehyde, 2,6-dichloro
benzaldehyde, 2,6-dimethoxy benzaldehyde) (1.0 mmol) was stirred
under reflux for 0.5–2.5 h in dry benzene/toluene (10 mL). Then,
mercaptoacetic acid (0.2 mL, 2 mmol) was added, and the mixture
was refluxed for further 3–45 h. The reaction was monitored by
TLC (Mobile phase: Cyclohexane and ethyl acetate 8:2, spots were
3-(4-chlorophenyl)-2-(4-nitrophenyl) thiazolidin-
4-one [2]
Yield: 0.68 g (38.47%); IR (KBr, in cm)1): 1688.56, 1432.80, 1373,
1
1348.78 (N=O str. for ArNO2), 872; HNMR (DMSO d6, d in ppm):
4.01 (d, 1H, J = 15.9 Hz, 5-HA), 4.25 (dd, 1H, J = 15.9 and 1.6 Hz,
5-HB), 6.08 (s, 1H, H-2), 7.04–8.13 (m, 8H, ArH); Mass: 335 (M+H)+;
Anal. Cal. C, 53.81; H, 3.31; N, 8.37; Found C, 53.95; H, 3.30; N,
8.40.
Table 1: Structure and physical constant of the synthesized compounds
R1
R2
N
3
2
1
4
S
O
5
Comp. code
R1
R2
Molecular formula
Mol. weight
Melting point (ꢀC)
Yield (%)
1
2
4-sulphonamidophenyl
4-chlorophenyl
pyridin-2-yl
5-chloropyridin-2-yl
6-methylpyridin-2-yl
4-sulphonamidophenyl
4,6-dimethylpyridin-2-yl
6-methylpyridin-2-yl
2-phenylethan-1-yl
2-phenylethan-1-yl
4-methoxyphenyl
4-nitrophenyl
2,5-dimethoxyphenyl
pyridin-2-yl
pyridin-2-yl
2-chlorophenyl
2,6-dichlorophenyl
2,6-dimethoxyphenyl
2,6-dichlorophenyl
2,5-dimethoxyphenyl
C16H16N2O4S2
C15H11ClN2O3S
C16H16N2O3S
C13H10ClN3OS
C14H13N3OS
C15H13ClN2O3S2
C16H17Cl2N2OS
C17H18N2O3S
C17H15Cl2N2OS
C19H21NO3S
364.4
334.7
316.3
291.7
271.3
368.8
353.2
330.4
352.2
343.4
Gummy
Gummy
40
38
41
42
43
40
38
44
41
40
3
130–132
155–157
163–165
85–87
128–130
146–148
210–212
179–181
4
5
6
7
8
9
10
Chem Biol Drug Des 2011; 78: 464–470
465

Ravichandran et al.
2-(2,5-dimethoxyphenyl)-3-(pyridin-2-yl)
thiazolidin-4-one [3]
2-(2,6-dichlorophenyl)-3-(4,6-dimethylpyridin-2-
yl) thiazolidin-4-one [7]
Yield: 0.65 g (41.27%); IR (KBr, in cm)1): 1694.13, 1578, 1472.70,
Yield: 0.67 g (37.68%); IR (KBr, in cm)1): 2962, 2873.36, 1697.27,
1
1
1362.86 (Ar-C-N str.), 1215.33; HNMR (DMSOd6, d in ppm): 3.71 (s,
1589.06, 1436.43, 1362.41 (Ar-C-N str.); HNMR (CDCl3, d in ppm):
6H, OCH3), 3.83 (d, 1H, J = 15.7 Hz, 5-HA), 4.12 (dd, 1H, J = 15.7
and 1.6 Hz, 5-HB), 5.95 (s, 1H, H-2), 6.47–6.56 (m, 3H, ArH), 7.18–
8.54 (m, 4H, pyridinyl); Mass: 317 (M+H)+; Anal. Cal. C, 60.74; H,
5.10; N, 8.85; Found C, 60.64; H, 5.09; N, 8.84.
2.39 (s, 3H, CH3), 2.57 (s, 3H, CH3), 3.89 (d, 1H, J = 15.6 Hz, 5-HA),
4.12 (dd, 1H, J = 15.6 and 1.4 Hz, 5-HB), 5.96 (s, 1H, H-2), 6.95 (s,
1H, pyridinyl), 6.98–7.03 (m, 3H, ArH), 8.09 (s, 1H, pyridinyl);
13CNMR (CDCl3): d 167.9, 156.8, 152.6, 149.3, 147.2, 138.3, 135.9,
127.7, 123, 120.6, 115.5, 58, 36; Mass: 354 (M+H)+; Anal. Cal. C,
54.40; H, 3.99; N, 7.93; Found C, 54.35; H, 4.00; N, 7.96.
3-(5-chloropyridin-2-yl)-2-(pyridine-2-yl)
thiazolidin-4-one [4]
Yield: 0.62 g (42.47%); IR (KBr, in cm)1): 1709.59, 1584.24 (C=N
str.), 1458.89, 1363.73; 1HNMR (CDCl3, d in ppm): 3.92 (d, 1H,
J = 15.1 Hz, 5-HA), 4.14 (d, 1H, J = 15.1 Hz, 5-HB), 6.16 (s, 1H, H-2),
7.29–7.83 (m, 3H, pyridinyl), 8.14–8.78 (m, 4H, pyridinyl); 13CNMR
(CDCl3): d 166.7, 158.6, 151.3, 149.4, 147.2, 138.3, 135.9, 127.7,
123, 120.6, 115.5, 58, 36; Mass: 292 (M+H)+; Anal. Cal. C, 53.52; H,
3.45; N, 14.40; Found C, 53.72; H, 3.45; N, 14.46.
2-(2,6-dimethoxyphenyl)-3-(6-methylpyridin-2-yl)
thiazolidin-4-one [8]
Yield: 0.72 g (43.64%); IR (KBr, in cm)1): 2870.69, 1694.13, 1585.84,
1497.47, 1358.32, 1215.33; 1HNMR (DMSOd6, d in ppm): 2.49 (s,
3H, CH3), 3.72 (s, 6H, OCH3), 3.89 (d, 1H, J = 15.4 Hz, 5-HA), 4.12
(d, 1H, J = 15.4 Hz, 5-HB), 5.92 (s, 1H, H-2), 6.21–6.81 (m, 3H, ArH),
7.13–8.16 (m, 3H, pyridinyl); Mass: 331 (M+H)+; Anal. Cal. C, 61.80;
H, 5.49; N, 8.48; Found C, 61.67; H, 5.51; N, 8.46.
3-(6-methylpyridin-2-yl)-2-(pyridine-2-yl)
thiazolidin-4-one [5]
2-(2,6-dichlorophenyl)-3-phenethylthiazolidin-4-
one [9]
Yield: 0.59 g (43.25%); IR (KBr, in cm)1): 2960, 1694.16, 1586.63,
1490, 1365 (Ar-C-N str.); 1HNMR (CDCl3, d in ppm): 2.46 (s, 3H,
CH3), 3.90 (d, 1H, J = 15.9 Hz, 5-HA), 4.14 (d, 1H, J = 15.9 Hz, 5-
HB), 6.46 (s, 1H, H-2), 7.08–7.23 (m, 2H, pyridinyl), 7.58–8.64 (m,
5H, pyridinyl); 13CNMR (CDCl3): d 168.2, 158.7, 156.3, 152.1, 149.5,
135.7, 123.3, 120.6, 118.6, 111.2, 58.6, 36.1, 20.7; Mass: 272
(M+H)+; Anal. Cal. C, 61.97; H, 4.83; N, 15.49; Found C, 61.85; H,
4.82; N, 15.56.
Yield: 0.72 g (40.79%); IR (KBr, in cm)1): 2925, 2852.8, 1685.28,
1432.85, 1244.97 (Al-C-N str.); 1HNMR (CDCl3, d in ppm): 2.81 (t,
2H, CH2), 3.43 (t, 2H, CH2), 3.85 (d, 1H, J = 15.7 Hz, 5-HA), 4.01 (dd,
1H, J = 15.7 and 1.9 Hz, 5-HB), 6.10 (s, 1H, H-2), 6.81–7.28 (m, 8H,
ArH); Mass: 353 (M+H)+; Anal. Cal. C, 57.96; H, 4.29; N, 3.98; Found
C, 58.08; H, 4.40; N, 3.96.
2-(2,5-dimethoxyphenyl)- 3-
2-(2-chlorophenyl)-3-(4-sulphonamidophenyl)
thiazolidin-4-one [6]
phenethylthiazolidin-4-one [10]
Yield: 0.69 g (40.05%); IR (KBr, in cm)1): 2925, 2852.8, 1703.56,
1434.78, 1238.83, 1024.37; 1HNMR (DMSOd6, d in ppm): 2.81 (t,
2H, CH2), 3.53 (t, 2H, CH2), 3.73 (s, 6H, OCH3), 3.89 (d, 1H,
J = 15.7 Hz, 5-HA), 4.15 (dd, 1H, J = 15.7 and 1.6 Hz, 5-HB), 5.92 (s,
1H, H-2), 6.46–6.54 (m, 3H, ArH), 7.08–7.48 (m, 5H, ArH); Mass:
344 (M+H)+; Anal. Cal. C, 66.45; H, 6.16; N, 4.08; Found C, 66.57;
H, 6.19; N, 4.05.
Yield: 0.73 g (39.57%); IR (KBr, in cm)1): 3416.17 (N-H str. for -
1
NH2), 1695.12, 1462.74, 1364.19; HNMR (CDCl3, d in ppm): 3.88 (d,
1H, J = 15.7 Hz, 5-HA), 4.12 (d, 1H, J = 15.7 Hz, 5-HB), 5.96 (s, 1H,
H-2), 6.93–8.02 (m, 8H, ArH), 10.08 (br s, 2H, SO2NH2); Mass: 369
(M+H)+; Anal. Cal. C, 48.84; H, 3.55; N, 7.59; Found C, 48.66; H,
3.56; N, 7.62.
Table 2: Antibacterial and anti-fungal activity of the compounds (MIC's in lg ⁄ mL)
Comp. code Escherichia coli Pseudomonas aeruginosa Bacillus subtilis Staphylococcus aureus Penicillium notatum Candida albicans Aspergillus niger
1
2
10
32
16
35
40
07
26
15
13
12
5
11
35
13
28
32
10
22
12
10
16
5
63
71
55
67
78
25
115
27
28
20
10
–
55
–
48
62
105
35
117
67
38
28
15
–
–
–
–
47
35
48
35
16
28
15
13
63
–
71
65
68
75
17
42
20
35
–
3
40
57
–
19
42
17
25
55
–
4
5
6
7
8
9
10
Cip
Flu
–
15
–
–
–
15
10
MIC, minimum inhibitory concentration; Cip, ciprofloxacin; Flu, fluconazole
466
Chem Biol Drug Des 2011; 78: 464–470

Design, Synthesis, Evaluation of Thiazolidinone Derivatives
Antimicrobial evaluation
humidified atmosphere of 5% CO2 in air. Five days after infection,
the viability of mock- and HIV-infected cells was examined spectro-
photometrically by the MTT method. The EC50 (effective concentra-
In vitro antibacterial activity
Synthesized compounds were evaluated for their in vitro antibacte-
rial activity against pathogenic bacteria. The agar dilution method
was carried out using Muller–Hinton agar (Hi-Media, Mumbai,
India) medium. Suspension of each micro-organism was prepared
and applied to plates with serially diluted compounds (DMF, solvent
control) to be tested and incubated (approximately 20 h) at 37 ꢀC.
The MIC was considered to be the lowest concentration that was
completely inhibited growth on agar plates. The bacteria strains
Pseudomonas aeruginosa (NCIM 2200), Staphylococcus aureus
(NCIM 2079), Escherichia coli (NCIM 2065), and Bacillus subtilis
(NCIM 2063) were used for this study (Table 2).
tion of compound (lM) achieving 50% protection in MT-2 cell lines
against the cytopathic effect of HIV-1) and CC50 (cytotoxic concen-
tration of compound (lM) required to reduce the viability of mock-
infected MT-2 cells by 50%) values (average of two experiments)
were calculated and reported.
Results and Discussion
The synthetic approach for the title compounds is shown in
Figure 1. Some 1,3-thiazolidin-4-ones were synthesized using the
methods reported by Rawal et al. (13), with slight modification. The
reaction was monitored by TLC. The structures of synthesized inter-
mediates were confirmed by IR spectra, and final compounds were
characterized by means of FTIR, 1HNMR, FAB-MS, and elemental
analyses.
In vitro antifungal activity
The compounds were evaluated for their in vitro anti-fungal activity
against pathogenic fungi using agar dilution method with Sabu-
roud's dextrose agar (Hi-Media). Suspension of each fungus was
prepared and applied to agar plates with serially diluted compounds
to be tested. The plates were incubated at 26 ꢀC for 72 h, and
MIC's were determined. The fungus strains Candida albicans (NCIM
3102), Aspergillus niger and Penicillium notatum (NCIM 742) were
used for this study (Table 2).
The investigation of antibacterial, antifungal, and anti-viral screen-
ing data revealed that all the tested compounds 1–10 showed
moderate-to-good inhibition. The compounds 1, 6, 8, 9, and 10
showed comparatively good activity against all the bacterial strains.
The good activity is attributed to the presence of pharmacologically
active sulphonamidophenyl group at R1, 2,6-dichlorophenyl, 2,5-
dimethoxyphenyl, and 2,6-dimethoxyphenyl groups attached at R2 of
the 1,3-thiazolidin-4-ones. Introduction of mono or dimethoxyphenyl
group and mono or dichlorophenyl at R2 caused enhancement in
activity. While introduction of 6-methylpyridine group at position R1
caused decrease in activity against most of the strains. The com-
pounds 3 and 4 exhibited moderate activity compared with that of
standard against all the bacterial strains.
In vitro anti-viral activity
Cytotoxicity and anti-viral activity of all compounds were evaluated
against Herpes simplex virus-1 and Herpes simplex virus-2 in HEL
cell culture. Cytotoxic concentration was measured, required to
cause a microscopically detectable alteration of normal cell mor-
phology. Cytopathogenicity was determined as a concentration
required to reduce virus-induced cytopathogenicity by 50%.
Compounds 1, 6, 9, and 10 showed good activity against E. coli,
while compounds 9 and 10 showed good activity against S. aur-
eus. The compounds 6, 7 (Figure 2), 8, and 9 showed compara-
tively good activity against all the fungal strains. The structures of
these compounds contain 2,6-dichlorophenyl, 2,5-dimethoxyphenyl,
and 2,6-dimethoxyphenyl groups attached at R2. The compounds 3
and 4 exhibited moderate activity against all fungal strains. Results
showed that aryl and heterocyclic substitution at R2 and R1 gave an
enhanced biological effect against all the tested bacterial and fun-
gal strains.
Compounds were also evaluated against influenza A H3N2 and
influenza B in Madin Darby canine kidney (MDCK) cell cultures and
50% cytotoxic concentration, as determined by measuring the cell
viability with the colorimetric formazan-based MTS assay. Similarly
50% Effective concentration, or concentration producing 50% inhibi-
tion of virus-induced cytopathic effect, was also determined by
visual scoring of the CPE, or by measuring the cell viability with the
colorimetric formazan-based MTS assay protocol.
The compounds were also tested for anti-HIV activity against repli-
cation of HIV-1 (III B) in MT-2 cells at varying concentrations from
100 nM by double dilution technique. The MT-2 cells were grown in
RPMI-1640 DM (Dutch modification) medium (Flow lab, Irvine, UK),
supplemented with 10% (v/v) heat-inactivated calf serum and 20-
mg/mL gentamicin (E. Merck, Darmstadt, Germany). HIV-1 (III B) was
obtained from the culture supernatant of HIV-1-infected MT-2 cell
lines, and the virus stocks were stored at )70 ꢀC until used.
Anti-HIV assays were carried out in microtitre plates filled with
100 mL of medium and 25 mL volumes of compounds in triplicate
so as to allow simultaneous evaluation of their effects on HIV and
mock-infected cells. Fifty microliters of HIV at 100 CCID50 medium
were added to either the HIV-infected or mock-infected part of the
microtitre tray. The cell cultures were incubated at 37 ꢀC in a
Title compounds were tested against representative members of
the virus including Herpes simplex virus-1 (KOS), Herpes simplex
virus-2 (G), Influenza A H3N2 subtype, Influenza B (Table 3) and
their cytotoxic concentration was evaluated. None of the synthe-
sized compounds are active against Herpes simplex virus-1 (KOS)
and Herpes simplex virus-2 (G). The same compound (7) showed
better anti-viral activity against Influenza A H3N2 subtype and Influ-
enza B at the concentration of 249–263 lM, where as cytotoxicity
was found to be >283 lM.
It is evident that the compound containing 2,6-dichlorophenyl group
attached at R2 of the was found to be most active compound
among the series. Interestingly, the same 2,6-dichlorophenyl group
Chem Biol Drug Des 2011; 78: 464–470
467

Ravichandran et al.
Step-1: Schiff’s base formation
R1
N
CH
R2
CHO
R1
NH2
+
-H2O
R2
Schiff's base formation
Step-2: Cyclo-condensation of Schiff’s base with thioglycolic acid
R1
OH
SH
+
N
CH
R2
O
Reflux
Dry benzene or toluene
R1
HN
R2
CH
HO
S
O
Cyclocondensation
-H2O
R1
R2
N
S
O
Where R1 and R2 is aromatic or heterocyclic ring
Figure 1: Scheme for the synthesis of 1,3-thiazolidin-4-one compounds.
at R2 and 2-phenylethane group at R1 (9) greatly reduce the spec-
trum of activity. It may be because of the increase in the distance
between the nitrogen atom (3rd position) of thiazolidinone and the
substitution ring at this position.
except 1, 2, 9, and 10 exhibited potent inhibitory activities against
HIV replication in this assay with EC50 values <1.07 lM. The most
promising 1,3-thiazolidin-4-one compound was 5 with EC50 values
of 0.078 and selectivity index (SI) of 205.
Synthesized compounds were also screened for their anti-HIV activ-
ity. The anti-HIV activity and cytotoxicity of synthesized compounds
against multiplication of wt HIV-1 (wild-type HIV-1) in acutely
infected MT-2 cell line and mock-infected MT-2 cell line, respec-
tively, were screened by MTT methods. The results are given in
Table 3. Azidothymidine (AZT), Nevirapine, was considered as refer-
ence drugs. All the synthesized 1,3-thiazolidin-4-ones compounds
The compounds 4, 5, and 7 (Figure 2) (EC50 = 0.078 to 0.108 lM)
were more potent than nevirapine (EC50 = 0.150 lM) in the same
assay, but all the thiazolidinone compounds were less potent than
AZT (EC50 = 0.007 lM). The compounds 1, 2, 9, and 10 were
found to be very less potent. 1,3-thiazolidin-4-one compounds
substituted with heterocyclic moiety at R2 and R1 by 2,6- dichlor-
phenyl and 2,5-dimethoxyphenyl substituent at R2 were found to be
468
Chem Biol Drug Des 2011; 78: 464–470

Design, Synthesis, Evaluation of Thiazolidinone Derivatives
N
Cl
N
S
N
N
N
N
S
H3C
O
O
Compound 4
Compound 5
CH3
H3C
CH3
N
N
H3C
S
O
Compound 7
Figure 2: Structure of some synthesized 1,3-thiazolidin-4-ones.
Table 3: Anti-viral activity of the synthesized compounds
Herpes simplex virus-1
Herpes simplex virus-2
Influenza A
Influenza B
HIV-1(IIIB)
H3N2 subtype
(in lM)
(in lM)
(in lM)
Comp. code
CC50
EC50
EC50
CC50
EC50
EC50
CC50
EC50
1
–
–
–
–
–
–
>274.42
–
–
–
>274.42
–
–
–
>274.42
–
–
–
‡181.65
‡154.60
>3
>10
>16
21 € 8.76
>65
>25
>228.15
>302.73
–
‡181.65
‡154.60
2
3
‡316.15
–
–
>271.15
‡184.03
>302.66
>283.93
>218.40
>391.80
–
>316.15
–
–
>271.15
130.24 € 4.86
296.61 € 15.55
>283.93
>316.15
–
–
>271.15
161.38 € 8.75
>302.66
>283.93
1.064 € 0.42
4
0.108 € 0.08
0.078 € 0.03
8.153 € 0.04
0.082 € 0.05
21.10 € 5.40
228.15 € 9.57
302.73 € 24.81
5
–
–
–
6
>271.15
>283.13
–
–
–
–
>409.48
–
–
>271.15
249.15 € 8.32
–
–
–
–
>271.15
263.31 € 12.17
–
–
–
–
7
8
9
10
>218.40
>218.40
Ganciclovir
Ribavirin
Azidothymidin
Nevirapine
0.196 € 0.070
0.196 € 0.058
–
–
–
–
–
–
–
–
32.76 € 1.40
24.57 € 0.55
–
–
–
–
–
–
–
70 € 3.03
50 € 2.53
0.007 € 0.002
0.150 € 0.003
EC50, effective concentration of compound (lM) achieving 50% protection in MT-2 cell lines against the cytopathic effect of HIV-1; CC50, cytotoxic concentration
of compound (lM) required to reduce the viability of mock-infected MT-2 cells by 50%.
more potent for their anti-HIV activity than the aromatic substitu-
tions at the aforementioned positions. The extrapolation of the dis-
tance between the nitrogen atom (3rd position) of thiazolidinone
and the substitution ring at this position (compounds 9) is not
favorable for anti-HIV activity. Highly electronegative substituents in
this position (compounds 10) are also not favorable for anti-HIV
activity. The results of the present study show that our approach
has led to the development of potent anti-HIV agents, more active
Chem Biol Drug Des 2011; 78: 464–470
469

Ravichandran et al.
than nevirapine. This is in conformity with the earlier observation
(13) namely, nature of the substituent at C-2 and N-3 of the thiaz-
olidin-4-one ring and butterfly conformation collectively facilitate
better interaction with the allosteric binding pocket residues of HIV-
1 RT enzyme. This has a direct bearing on the anti-HIV activity.
5. Look G.C., Schullek J.R., Holmes C.P., Chinn J.P., Gordon E.M.,
Gallop M.A. (1996) The identification of cyclooxygenase-1 inhibi-
tors from 4-thiazolidinone combinatorial libraries. Bioorg Med
Chem Lett;6:707–712.
6. Chimirri A., Grasso S., Monforte A.M., Zappala M., De Sarro A.,
De Sarro G.B. (1991) Synthesis, anticonvulsant properties of 3-
(1,3,4-thiadiazol-2-yl)thiazolidin-4-ones. Farmaco;46:935–943.
7. Barreca M.L., Chimirri A., De Luca L., Monforte A.M., Monforte
P., Rao A., Zappala M., Balzarini J., De Clercq E., Pannecouque
C., Witvrouw M. (2001) Discovery of 2,3-diaryl-1,3-thiazolidin-4-
ones as potent anti-HIV-1 agents. Bioorg Med Chem
Lett;11:1793–1796.
8. Barreca M.L., Balzarini J., Chimirri A., De Clercq E., De Luca L.,
Ho H.D., Ho H., Monforte A.M., Monforte P., Pannecouque C.,
Rao A., Zappala M. (2002) Design, synthesis, structure–activity
relationships, molecular modeling studies of 2,3-diaryl-1,3-thiaz-
olidin-4-ones as potent anti-HIV agents. J Med Chem;45:5410–
5413.
9. Chimirri A., Grasso S., Monforte A.M., Zappala M. (1991) Anti-
HIV agents Synthesis II., in vitro anti-HIV activity of novel
1H,3H-thiazolo[3,4-a]benzimidazoles. Farmaco;46:925–933.
10. Rao A., Balzarini J., Carbone A., Chimirri A., De Clercq E.,
Monforte A.M., Monforte P., Pannecouque C., Zapalla M. (2004)
In terms of SARs, we can say that the anti-HIV activity was strongly
enhanced by introducing a 2-pyridinyl substituent at R1 of the thia-
zolidinone ring and in particular by 2-pyridinyl, two chlorine atoms
at 2¢ and 6¢ positions of the phenyl ring at C-2: in fact, derivative
5 was more active than its analogues 4 and 7, while compound 7
was more active than 9 and 10. As suggested by molecular model-
ing studies (18), the introduction of a lipophilic substituent in the
hetero-aromatic ring led to a substantial increase in the anti-viral
activity. Moreover, we learned that the introduction of a methyl
group at the 6 position of the pyridin-2-yl group led to a substantial
increase in potency thus confirming that increasing the steric bulk
of this aromatic part led to improved anti-viral activity, our findings
are consistent with the report of Rao et al. (10).
Conclusion
The research study reports the successful synthesis, antibacterial,
antifungal, and anti-viral activity of new 1,3-thiazolidin-4-ones carry-
ing biologically active groups at C-2 (position 2) and N (position 3).
Their antimicrobial activity study revealed that all of the tested
compounds showed moderate-to-good antibacterial and antifungal
activities against pathogenic strains. Only few of the synthesized
compounds showed better anti-HIV activity than nevirapine. It can
be concluded that a combination of two different heterocyclic sys-
tems namely 1,3-thiazolidin-4-one and 2-pyridinyl ring (substituted)
with an aromatic system namely 2,6-disustituted phenyl or 2-pyridi-
nyl ring has enhanced the antimicrobial and anti-viral effect and
hence, they are ideally suited for further modifications to obtain
more efficacious antimicrobial compounds.
2-(2,6-Dihalophenyl)-3-(pyrimidin-2-yl)-1,3-thiazolidin-4-ones
non-nucleoside HIV-1 reverse transcriptase inhibitors. Antiviral
Res;63:79–84.
as
11. Rao A., Carbone A., Chimirri A., De Clercq E., Monforte A.M.,
Monforte P., Pannecouque C., Zapalla M. (2002) Synthesis, anti-
HIV activity of 2,3-diaryl-1,3-thiazolidin-4-(thi)one derivatives. Far-
maco;57:747–751.
12. Rao A., Balzarini J., Carbone A., Chimirri A., De Clercq E., Mon-
forte A.M., Monforte P., Pannecouque C., Zapalla M. (2004) Syn-
thesis of new 2,3-diaryl-1,3-thiazolidin-4-ones as anti-HIV
agents. Farmaco;59:33–39.
13. Rawal R.K., Tripathi R., Katti S.B., Pannecouque C., De Clercq E.
(2007) Design, synthesis, evaluation of 2-aryl-3-heteroaryl-
1,3-thiazolidin-4-ones as anti-HIV agents. Bioorg Med
Chem;4:1725–1731.
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