Synthesis and Study of Some New 2-Imino-3-[Carboxamido o-hydroxyphenyl]-5-Arylidene-4-Thiazolidinone as Antibacterial Agents
Patel VI*, Patel RG, Patel NG, Panchal SR and Bhardia PD
Dep. of Pharmaceutical and Medicinal Chemistry, B.S. Patel Pharmacy College, Linch, Mehsana ,Gujarat, India.
*Corresponding Author E-mail: patelvimal95@yahoo.com
ABSTRACT:
Some New 2-Imino-3-[Carboxamido o-hydroxy Phenyl]-5-Arylidene-4-Thiazolidinone, unsubstituted or carrying hydroxy, nitro and chloro groups on the benzene ring, were synthesized and assayed in vitro for their antibacterial activity against Gram positive and Gram negative bacteria by the cup-plate method . The 5-arylidene derivatives showed an antibacterial efficacy considerably greater than that of the parent 2-imino-3-(carboxamido p-hydroxyphenyl)-thiazolidine-4-one, suggesting that the substituted and unsubstituted 5-arylidene moiety plays an important role in enhancing the antibacterial properties of this class of compounds. All the title compounds characterised on the basis of their IR, MASS, 1H NMR spectroscopic data analysis. The synthesized compounds were screened for their in vitro antibacterial activity against Staphylococcus aureus, B. citrus, Escherichia coli, by measuring the zone of inhibition in mm. The antibacterial activity was performed by cup plate method at concentration 20µg/ml and 50µg/ml and reported. Nutrient agar was employed as culture medium and DMF was used as solvent control. Streptomycin used as standard for antibacterial activity. From the antibacterial screening it was observed that all the compounds exhibited activity against all the organisms employed. Compound bearing -2ClC6H4, -4ClC6H4 substituents shows better anti bacterial activity than other compounds.
KEYWORDS: 2-imino-3-(carboxamido o-hydroxyphenyl)-thiazolidine-4-one; Thiazolidinone derivatives; Antibacterial activity.
The treatment of infectious diseases still remains an important and challenging problem because of a combination of factors including emerging infectious diseases and the increasing number of multi-drug resistant microbial pathogens with particular relevance for Gram positive bacteria1.
The therapeutic problem has achieved increasing importance in hospitalised patients, in immune suppressed patients with AIDS or undergoing anticancer therapy and organ transplants. In spite of a large number of antibiotics and chemotherapeutics available for medical use, at the same time the emergence of old and new antibiotic resistance created in the last decades a substantial medical need for new classes of antibacterial agents. A potential approach to overcome the resistance problem is to design innovative agents with a different mode of action so that no cross resistance with the present therapeutically can occur.
4-Thiazolidinone2,3 scaffold show remarkable antimicrobial activity4, in addition to various biological properties, such as ant proliferative, antiviral5, ant tuberculosis, antiinflammatory6, antihistaminic7. The presence of halogen substituted arylidine ring on fifth position of thiazolidinone is found to be responsible for antibacterial activity. The structure of the synthesized compounds were elucidated on the basis of their IR, MASS, 1H NMR spectroscopic data. These compounds also screened for their antibacterial activity.
EXPERIMENTAL:
Melting points of all the synthesized compounds were determined in open capillaries and are uncorrected. Thin layer chromatography was performed on microscopic slides (2×7.5cm) coated with Silica-Gel-Gf254 and spots were visualized under UV light and by exposure to iodine vapour. IR spectra of all compounds were recorded in FTIR 8400S Shimadzu Spectrophotometer using KBR. Mass spectra were obtained using 2010EV LCMS Shimadzu instrument. The 1H-NMR was recorded on Bruker Advance-II NMR 400 MHz instruments using CDCl3 / DMSO-d6 as solvent and TMS (tetramethylsilane) as internal standard, chemical shifts were expressed as δ values (ppm).
All the chemicals use for the synthesis of titled compounds was produced from S.D. Fine Chem. Ltd, Phenar Chemical Ltd, and Loba Chemicals. The chemicals were used without further purification.
Preparation of methyl O-hydroxybenzoate (2):
A mixture of O-hydroxybenzoic acid 13.8g (0.1mol) absolute methyl alcohol 32ml (1.5mol) and concentrated sulphuric acid 2ml (0.02mol) was taken in 250ml round bottom flask. Add a few small chips of porous porcelain attach a reflux condenser. The reaction mixture was refluxed for 5 hours. After cooling the mixture, add the water until white precipitate of methyl O-hydroxybenzoate were formed. Filter the precipitate and it washed with water. Dry the precipitate and crystallized form dilute alcohol yielded 10.5g (71.68%w/w) of crystalline product. M.P..: 110-114˚C. IR (KBr cm-1): 1681, 1725 (-C=O, ester), 1163 (-C-O, phenol), 3052 (Ar C-H)
Preparation of O-hydroxybenzohydrazide (3):
A reaction mixture of o-hydroxybenzoate 10g (0.065mol), hydrazine hydrate 6 ml (0.12ml) was taken in 250ml round bottom flask with reflux condenser.
Then just enough absolute ethanol was added through condenser, to produce clear solution. The reaction mixture was refluxed for 4 hours. Distilled off the ethanol by distillation. On cooling the mixture white crystal of O-hydroxybenzohydrazide was formed. The product was dried and recrystalized from dilute alcohol yielded 6.8g (68%w/w) crystalline Product. m.p.: 180-184˚C. I.R (KBr cm-1): ~1650 (C=O), ~3324 (-N-H), 1174(-C-O, phenol), ~3012 (Ar C-H).
Preparation of O-hydroxybenzonoyl Thiosemicarbazide (4):
A reaction mixture of O-hydroxybenzohydrazide 6g (0.039mol), potassium thiocynate 7.84g (0.08mol), concentrated HCl 3ml and water 20ml was taken in 100ml round bottom flask with reflux condenser. Then it was refluxed for 4 hours until solid separated. The resulting solid that separated was washed with hot water and crystallized from methanol yielded 4.5 g (67.36%w/w) of crystalline product. M.P.: 210-212.
I.R (KBr cm-1): ~1649 (C=O), ~3524 (-N-H), 1174(-C-O, phenol), ~3131 (Ar C-H).
|
Compd. code |
Ar |
Mol. Formulae |
M.P. |
Yield (%w/w) |
Rf a |
Composition C, H, N (%) |
|
6a |
C6H5 |
C17H13N3O3S |
248-2520 |
50.00 |
0.50 |
C-60.17, H-3.86, N-12.58 |
|
6b |
2-ClC6H4 |
C17H12ClN3O3S |
252-254 |
41.23 |
0.52 |
C-54.62, H-3.24, N-11.24 |
|
6c |
4-ClC6H4 |
C17H12ClN3O3S |
250-252 |
43.94 |
0.56 |
C-54.62, H-3.24, N-11.24 |
|
6d |
3-NO2C6H4 |
C17H12N4O5S |
256-260 |
45.36 |
0.58 |
C-53.12, H-3.15, N-14.58 |
|
6e |
4-NO2C6H4 |
C17H12N4O5S |
265-267 |
49.29 |
0.51 |
C-53.12, H-3.15, N-14.58 |
|
6f |
4-OHC6H4 |
C17H13N3O2S |
258-260 |
30.71 |
0.44 |
C-57.46, H-11.82, N-11.82 |
Table- 1. Physicochemical data of the compounds (6a-f):
a Mobile phase Toluene: Methanol (8:2)
Table -2. Spectral data of the compounds (6a-f):
|
Compd. Code |
Mol. Wt. (g/mol) |
I.R (cm-1 , KBr) |
Mass (m/e) |
1H NMR (DMSO-d6, ppm) |
|
6a |
339.36 |
~3460 (-N-H), ~1646 (C=O), ~3250 (O-H), 1506,1580 (-N-H amide), 1456 (C=N imino), 1240 (C-N), 1160(-C-O phenol), 3051 (Ar C-H) |
339.9 (M+) 341.9 (M+2) |
7.98(d,5H,phenyl),6.84(d,2H,Ar), 7.52(d,2H,Ar), 7.8(s,1H,-CONH), 8.0(s,1H,-C=NH), 1H (-OH) deuterium exchangeable
|
|
6b |
373.81 |
~3390 (-N-H), ~1650 (C=O), 1519,1558 (-N-H amide), ~1460 (C=N imino), 1250 (C-N), 1160 (-C-O phenol) |
373.1 (M+) 375.1 (M+2) |
6.9(d,2H,Ar),7.4(d,2H,Ar),7.6(d,2H,Ar), 7.9(d,2H,Ar), 7.8(s,1H,-CONH), 8.1(s,1H,-C=NH), 1H (-OH) deuterium exchangeable
|
|
6c |
373.81 |
~3420(-N-H),1646 (C=O), 1520,1580 (-N-H amide), 1456 (C=N imino), 1305 (C-N),1160 (-C-O phenol),3024 (Ar C-H) |
373.1 (M+) 375.1 (M+2) |
6.8(d,2H,Ar),7.4(d,2H,Ar), 6.95(d,2H,Ar), 7.6(d,2H,Ar), 7.8(s,1H,-CONH), 8.1(s,1H,-C=NH), 1H (-OH) deuterium exchangeable
|
|
6d |
384.36 |
~3385 (-N-H), ~1646 (C=O), 1510,1570 (-N-H amide), ~1460 ( C=N imino), 1240 (C-N), 1160 (-C-O phenol),1336 (-N=O nitro), 3024 (Ar C-H) |
385.1 (M+) 387.1 (M+2) |
7.98(d,5H,phenyl),6.84(d,2H,Ar), 7.52(d,2H,Ar), 7.8(s,1H,-CONH), 8.0(s,1H,-C=NH), 1H (-OH) deuterium exchangeable
|
|
6e |
384.36 |
~3350 (-N-H),~1640(C=O), 1500,1580 (-N-H amide), 1460 (C=N imino), 1160 (-C-O phenol), 1336 (-N=O nitro), 3052 (Ar C-H) |
385(M+) 387 (M+2)
|
6.8(d,2H,Ar),7.4(d,2H,Ar), 7.7(d,2H,Ar), 8.2(d,2H,Ar), 7.8(s,1H,-CONH), 8.01(s,1H,-C=NH), 1H (-OH) deuterium exchangeable |
|
6f |
355.36 |
~3360 (-N-H), ~1640 (C=O), 1500,1580 (-N-H amide), ~1460 (C=N imino),1160 (-C-O phenol), 3050 (Ar C-H) |
355.1 (M+) 357.1 (M+2) |
6.87(d,2H,Ar),7.43(d,2H,Ar), 6.95(d,2H,Ar), 7.56(d,2H,Ar), .8(s,1H,-CONH), 8.2(s,1H,-C=NH), 1H (-OH) deuterium exchangeable |
Preparation of 2-imino-3-(carboxamido O-hydroxyphenyl)-4-thiazolidinones (5):
A reaction mixture of O-hydroxybenzonoyl Thiosemicarbazide 4gm (0.015mol), monochloroacetic acid 2.42g (0.015mol) and anhydrous sodium acetate 2.46g (0.03mol) and glacial acetic acid 20ml was taken into 100 round bottom flask with reflux condenser. The reaction mixture was refluxed for 6 hours. After cooling, the reaction mixture was poured on crushed ice and resulting yellowish solid was separated. It was washed with hot water and crystallized from methanol yielded 1.2 g (41.95%w/w) of crystalline product. m.p.: 236-240.
I .R (KBr cm-1): 1648, 1699 (C=O), ~3424 (-N-H), 1456 (C=N imino), 1160(-C-O, phenol), ~3042 (Ar C-H).
Preparation of 2-imino-3-(carboxamido O-hydroxyphenyl)-5-(phenyl)-4-thiazolidinones (6a):
A reaction mixture of 2-imino-3-(carboxamido O-hydroxyphenyl)-4-thiazolidinones 0.5g (0.002mol), benzaldehyde 0.2ml (0.002mol) and anhydrous sodium acetate 0.164g (0.002mol) in glacial acetic acid (10ml) was taken into 50ml round bottom flask with reflux condenser. The reaction mixture was refluxed for 6 hours. After cooling, the reaction mixture was poured on crushed ice and resulting solid was washed with hot water and crystallized from methanol yielded 0.35g (52.23%w/w) of crystalline product. M.P.: 250-252˚C. Similarly remaining compounds was prepared by above method. The characterization data of these compounds is described in Table-1 and 2.
ANTIBACTERIAL ACTIVITY:
The synthesized compounds (6a-f) were screened for their in vitro antibacterial activity against Staphylococcus aureus,B. citrus, Escherichia coli, by measuring the zone of inhibition in mm. The antibacterial activity was performed by cup plate method8,9 at concentration 20µg/ml and 50µg/ml and reported in Table-3. Nutrient agar was employed as culture medium and DMF was used as solvent control. Streptomycin were used as standard for antibacterial activities.
Table- 3. Antibacterial data of compounds (6a-f):
|
Compd. Code |
Antibacterial |
|||||
|
S. aureus |
B. citrus |
E. coli |
||||
|
20 (µg/ml) |
50 (µg/ml) |
20 (µg/ml) |
50 (µg/ml) |
20 (µg/ml) |
50 (µg/ml) |
|
|
5 |
- |
6 |
- |
4 |
- |
3 |
|
6a |
4 |
12 |
5 |
12 |
2 |
7 |
|
6b |
9 |
20 |
7 |
18 |
6 |
15 |
|
6c |
9 |
19 |
7 |
17 |
6 |
14 |
|
6d |
7 |
17 |
6 |
15 |
5 |
13 |
|
6e |
8 |
18 |
6 |
16 |
5 |
13 |
|
6f |
6 |
15 |
4 |
14 |
3 |
12 |
|
Streptomycin |
12 |
23 |
10 |
21 |
9 |
20 |
|
DMF |
-- |
-- |
-- |
-- |
-- |
-- |
a zone of inhibition in mm
CONCLUSION:
From the antibacterial screening it was observed that all the compounds exhibited activity against all the organisms employed. Looking at the structure activity relationship marked inhibition in bacteria was observed the compound bearing Ar = 2-Cl C6H4, 4-ClC6H4 substituent’s where as other compounds showed moderate to good activity. All the compounds showed moderate to less activity as compared to standard.
ACKNOWELEDGEMENT:
The authors are thankful to Department of Pharmaceutical and Medicinal Chemistry of B. S. Patel Pharmacy College, Linch, Mehsana, Gujarat, India and Shri Sarvajanik Pharmacy College, Mehsana, Gujarat, India to fulfill the project work successfully.
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Received on 22.12.2009 Modified on 08.02.2010
Accepted on 27.03.2010 © AJRC All right reserved
Asian J. Research Chem. 3(2): April- June 2010; Page 468-471