Synthesis and Evaluation of Some New Imidazole Derivatives for their Anti-Microbial and Anti-Inflammatory activities

 

Hemlata Bhawar1*, Nachiket  Dighe1, Pankaj Shinde1,  Ravi Lawre2 and  Sanjay Bhawar3

1Department of Pharmaceutical Chemistry, Pravara Rural College of Pharmacy, Loni, MS, India-413736.

2Department of Quality Assurance Technique, Pravara Rural College of Pharmacy, Loni, MS, India-413736.

3Department of Pharmacology, Pravara Rural College of Pharmacy, Loni, MS, India-413736.

*Corresponding Author E-mail: nachiketvirat@gmail.com

 

ABSTRACT:

The synthesis, structure and biological activity of Imidazole derivatives have long been the focus of research interests in the field of Medicinal Chemistry. A number of Imidazole derivatives have been reported to possess interesting biological activities such as Antimicrobial, Anti-inflammatory and Antifungal activities etc. Around 22 new derivatives were synthesized, with the standard chemicals and well established procedures. The synthesized compounds were tested for their preliminary tests, physical constants, TLC etc. IR, 1H-NMR Spectra and CHN analysis confirmed the structures of the final compounds. The proposed compounds were screened for their antimicrobial and anti-inflammatory activities with the standard drugs in the well-equipped microbiology and pharmacology lab by using standard methods.

 

KEYWORDS: Anti-inflammatory, Antimicrobial and Imidazole

 


INTRODUCTION:

The diverse biological activities of imidazole derivatives made an impact to direct the attention of medicinal chemist as a promising class of a heterocyclic compounds with profound biological activities. Varied bioactivities exhibited by imidazole, efforts have been made from time to time to generate libraries of these compounds and screened them for potential biological activities. Also it is well documented that imidazole nucleus is associated with a variety of pharmacological actions. It displays pronounced anticonvulsant activity, anticancer, anthelmintic activity, and antiproliferative activity. Extensive biochemical and pharmacological studies have confirmed that imidazole molecules are effective against various strains of microorganisms. Looking at the importance of imidazole nucleus, it was thought that it would be worthwhile to design and synthesize some new imidazole derivatives and screen them for potential biological activities.

 

MARERIALS AND METHODS:

EXPERIMENTAL:

Melting points were determined in open capillary method and are uncorrected. Purity of the compound was checked on Silica gel TLC plates. IR spectra were recorded on Jasco FT/IR-4100 spectrophotometer using KBr disc method. 1HNMR spectra were recorded on Bruker Advance –II 400, DMSO as internal standard. Combustion analyses were found to be within the limits of permissible errors.

 

ANTIBACTERIAL ACTIVITY:

The newly synthesized compounds were screened for their antibacterial activity against Escherichia coli (MTCC 443), Bacilus subtilis (ATCC12228) and Staphylococcus aureus (ATCC25923) bacterial strains by disc diffusion method. In all the determinations tests were performed in triplicate and the results were taken as a mean of three determinations. Ciprofloxacin was used as a standard drug1.

 

ANTI-INFLAMMATORY ACTIVITY:

In-vitro anti-inflammatory activity

Inhibition of protein denaturation

The standard drug and synthesized compounds were dissolved in minimum quantity of dimethyl formamide (DMF) and diluted with phosphate buffer (0.2 M, pH 7.4). Final concentration of DMF in all solution was less than 2.5%. Test solution (1mL) containing different concentrations of drug was mixed with 1 mL of 1mM albumin solution in phosphate buffer and incubated at 27° + 1° C in BOD incubator for 15 min. Denaturation was induced by keeping the reaction mixture at 60° + 1° C in water bath for 10 min. After cooling, the turbidity was measured at 660 nm (UV-Visible Spectrophotometer). Percentage of inhibition of denaturation was calculated from control where no drug was added. Each experiment was done in triplicate and average is taken. The Ibuprofen was use as standard drug. The percentage inhibition of denaturation was calculated by using following formula.

 

% of Inhibition = 100 X [1- Vt / Vc]

 

Where,

Vt = Mean absorbance of test sample.

Vc = Mean absorbance of control2-4

 

PROCEDURE FOR SCHEME-I

Synthesis of 2, 4, 5- trisubstituted imidazoles (A1-A11)

0.01 mole of benzil was mixed with 0.01 mole of aromatic aldehyde along with ammonium acetate and PPA, and refluxed for 3 hrs. Cool pour the reaction mixture on ice to offer solid mass, filtered and recrystallized from hot ethanol to offer titled compounds (A1-A11).

 

PROCEDURE FOR SCHEME-II

Synthesis of 2, 4, 5- trisubstitutedimidazoles (B1-B11)

0.01 mole of ethanedione was mixed with 0.01 mole of aromatic aldehyde along with ammonium acetate and PPA, and refluxed for 3 hrs. Cool pour the reaction mixture on ice to offer solid mass, filtered and recrystallized from hot ethanol to offer titled compounds (B1-B11).


 

SCHME: I

SCHME: II

 

 


SPECTRAL DATA:

A1: IR (KBr) cm-1: 3517.67 (-OH str.), 3213.45 (-NH str.), 3063.06 (Ar-CH str.), 2885.60 (-NH str.), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 9.68 (OH, Aromatic C-OH), 13.4 (1H NH).

 

A2: IR (KBr) cm-1:1320 (-C–O str.), 3010.23 (Ar-CH str.), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 3.83(3H-OCH3), 13.4 (1H NH).

 

A3: IR (KBr) cm-1:  3213.45 (-NH str.), 3010.23 (Ar-CH str.), 1525.32 (-C=N str) 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (15 H phenyl), 13.4 (1H NH).

A4: IR (KBr) cm-1:3213.45 (-NH str.), 3010.23 (Ar-CH str.), 740 (-C –Cl str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 13.4 (1H NH).

 

A5: IR (KBr) cm-1: 3010.23 (Ar-CH str.), 1510 (- N –O str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 13.4 (1H NH).

 

A6: IR (KBr) cm-1: 3010.23 (Ar-CH str.), 1510 (- N –O str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 13.4 (1H NH).

 

A7: IR (KBr) cm-1:3213.45 (-NH str.), 3010.23 (Ar-CH str.), 740 (-C –Cl str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 13.4 (1H NH).

 

A8: IR (KBr) cm-1: 3010.23 (Ar-CH str.), 1510 (- N –O str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 13.4 (1H NH).

 

A9: IR (KBr) cm-1: 3213.45 (-NH str.), 3010.23 (Ar-CH str.), 740 (-C –Cl str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 13.4 (1H NH).

 

A10: IR (KBr) cm-1: 3517.67 (-OH str.), 3213.45 (-NH str.), 3063.06 (Ar-CH str.), 2885.60 (-NH str.), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 9.68 (OH, Aromatic C-OH), 13.4 (1H NH).

 

A11: IR (KBr) cm-1: 3213.45 (-NH str.), 3063.06 (Ar-CH str.), 2885.60 (-NH str.), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 13.4 (1H NH).

 

B1: IR (KBr) cm-1: 3517.67 (-OH str.), 3213.45 (-NH str.), 3063.06 (Ar-CH str.), 2885.60 (-NH str.), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 9.68 (OH, Aromatic C-OH), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

 

B2: IR (KBr) cm-1:1320 (-C–O str.), 3010.23 (Ar-CH str.), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 3.83(3H-OCH3), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

 

B3: IR (KBr) cm-1:3213.45 (-NH str.), 3010.23 (Ar-CH str.), 1525.32 (-C=N str) 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (15 H phenyl), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

 

B4: IR (KBr) cm-1:3213.45 (-NH str.), 3010.23 (Ar-CH str.), 740 (-C –Cl str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

 

B5: IR (KBr) cm-1:3010.23 (Ar-CH str.), 1510 (- N –O str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

 

B6: IR (KBr) cm-1:3010.23 (Ar-CH str.), 1510 (- N –O str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

 

B7: IR (KBr) cm-1:3213.45 (-NH str.), 3010.23 (Ar-CH str.), 740 (-C –Cl str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR:ppm): 6.8-7.2 (14 H phenyl), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

B8: IR (KBr) cm-1:3010.23 (Ar-CH str.), 1510 (- N –O str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

 

B9: IR (KBr) cm-1:3213.45 (-NH str.), 3010.23 (Ar-CH str.), 740 (-C –Cl str), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

 

B10: IR (KBr) cm-1:3517.67 (-OH str.), 3213.45 (-NH str.), 3063.06 (Ar-CH str.), 2885.60 (-NH str.), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 9.68 (OH, Aromatic C-OH), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

B11: IR (KBr) cm-1:3213.45 (-NH str.), 3063.06 (Ar-CH str.), 2885.60 (-NH str.), 1525.32 (-C=N str), 1245.36 (-C-N str). 1H NMR: (δ ppm): 6.8-7.2 (14 H phenyl), 3.07 (2H CH2), 1.25 (3H CH3), 13.4 (1H NH).

 

 


 

Table no. 1: Analytical and Physicochemical data of the synthesized compounds (A1-A11)

Comp.

Mol. Formula

Mol. Wt.

M.P.

° C

Yield

%

Elemental analyses

Calcd. (found)

C

H

N

A1

C21H16 N2O

312

445-450

68

80.71

5.11

8.93

A2

C22H18N2O

326

380-384

65

80.94

5.52

8.53

A3

C21H16N2

296

334-344

67

85.5

5.40

9.40

A4

C21H15ClN2

330

376-385

56

76.19

4.52

8.42

A5

C21H15N3O2

341

410-415

58

73.85

4.39

12.30

A6

C21H15N3O2

341

425-435

69

73.59

4.39

12.30

A7

C21H15ClN2

330

376-384

72

76.20

4.52

8.42

A8

C21H15N3O2

341

430-440

58

73.85

4.39

12.31

A9

C21H15ClN2

330

376-386

71

76.20

7.52

8.42

A10

C21H16N2O

312

445-455

72

80.70

5.11

8.93

A11

C23H21N3

339

401-410

67

81.32

6.20

12.35

 

 

Table no. 2: Analytical and Physicochemical data of the synthesized compounds (B1-B11)

Comp.

Mol. Formula

Mol. Wt.

M.P.

° C

Yield

%

Elemental analyses

Calcd. (found)

C

H

N

B1

C13H16 N2O

216

302-310

68

72.16

7.43

12.91

B2

C14H18N2O

230

273-283

65

73.01

7.84

12.13

B3

C13H16N2

200

191-200

67

77.93

8.01

13.96

B4

C13H15ClN2

234

320-330

56

66.48

6.40

11.90

B5

C13H15N3O2

245

325-330

58

63.62

6.13

17.09

B6

C13H15N3O2

245

340-350

69

63.62

6.13

17.09

B7

C13H15ClN2

234

233-240

72

66.48

6.40

11.90

B8

C13H15N3O2

245

325-330

58

63.62

6.13

17.09

B9

C13H15ClN2

234

320-330

71

66.48

6.40

11.90

B10

C13H16N2O

216

302-310

72

72.16

7.43

12.91

B11

C15H21N3

243

310-320

67

74.03

8.65

17.23

 

 

Table no: 3 Antibacterial activity of synthesized compounds (A1-A11) (Scheme-I)

Compd.

Zone of inhibition at 200µcg/mL (in mm.)

 

E. coli

B. Subtilis

S. aureus

A. niger

C. albicans

A1

24

25

26

15

22

A2

20

23

25

16

21

A3

20

24

25

19

22

A4

25

26

23

20

21

A5

24

23

26

21

22

A6

20

22

24

18

23

A7

21

23

22

20

21

A8

22

24

25

20

22

A9

23

22

20

18

22

A10

24

26

23

19

21

A11

21

23

22

20

21

Ciprofloxacin

26

25

26

-

-

Griseofulvin

-

-

-

22

23

 

 

Table no: 4 Antibacterial activities of synthesized compounds (B1-B11) (Scheme-II)

Compd.

Zone of inhibition at 200µcg/mL (in mm.)

 

E. coli

B. Subtilis

S. aureus

A. niger

C. albicans

B1

24

26

23

19

21

B2

25

23

24

21

23

B3

26

22

24

20

22

B4

24

25

26

21

23

B5

23

25

26

20

22

B6

26

23

26

20

21

B7

26

23

25

19

21

B8

25

24

26

20

21

B9

25

26

26

21

20

B10

21

22

23

19

21

B11

23

26

22

19

21

Ciprofloxacin

26

25

26

-

-

Griseofulvin

-

-

-

22

23

 

 

Table no. 5: Anti-inflammatory activity of synthesized compounds (A1-A11) (Scheme-I)

Treatment

Mean increase in paw volume (ml)±SEM

Time in minute

0

% inhi.

30

% inhi.

60

% inhi.

90

% inhi.

120

% inhi.

Carrageenan

(Control)

0.24±0.01

 

0.48±0.03

 

0.78±0.09

 

0.85±0.12

 

0.89±0.14

 

Ibuprofen

0.24±0.03

0

0.31±0.07

35.41

0.30±0.07

61.53

0.27±0.06

68.23

0.26±0.13

70.78

A1

0.24±0.01

0

0.34±0.03

29.16

0.35±0.01

55.12

0.33±0.01

61.17

0.30±0.01

66.29

A2

0.24±0.02

0

0.33±0.03

31.25

0.32±0.01

58.97

0.30±0.01

64.70

0.28±0.02

68.53

A3

0.23±0.01

4.16

0.34±0.01

29.16

0.38±0.01

51.28

0.38±0.02

55.29

0.32±0.02

64.04

A4

0.24±0.02

0

0.33±0.01

31.25

0.33±0.02

57.69

0.31±0.02

63.52

0.29±0.01

67.41

A5

0.23±0.01

4.16

0.32±0.01

33.33

0.34±0.01

56.41

0.32±0.01

62.35

0.30±0.02

66.29

A6

0.24±0.02

0

0.35±0.01

27.08

0.39±0.02

50

0.38±0.01

55.29

0.32±0.03

64.04

A7

0.23±0.02

4.16

0.33±0.01

31.25

0.35±0.02

55.12

0.34±0.02

60

0.30±0.01

66.29

A8

0.24±0.02

0

0.33±0.02

31.25

0.35±0.03

55.12

0.31±0.02

63.52

0.30±0.02

66.29

A9

0.23±0.03

4.16

0.33±0.02

31.25

0.34±0.01

56.41

0.32±0.02

62.35

0.30±0.02

66.29

A10

0.24±0.01

0

0.32±0.02

33.33

0.34±0.02

56.41

0.33±0.01

61.17

0.29±0.01

67.41

A11

0.24±0.02

0

0.34±0.03

29.16

0.34±0.03

56.41

0.35±0.01

58.82

0.31±0.02

65.16

% inhi.= % inhibition

 

 

Table no. 6: Anti-inflammatory activity of synthesized compounds (B1-B11) (Scheme-II)

Treatment

Mean increase in paw volume (ml)±SEM

Time in minute

0

% inhi.

30

% inhi.

60

% inhi.

90

% inhi.

120

% inhi.

Carrageenan

(Control)

0.24±0.01

 

0.48±0.03

 

0.78±0.09

 

0.85±0.12

 

0.89±0.14

 

Ibuprofen

0.24±0.03

0

0.31±0.07

35.41

0.30±0.07

61.53

0.27±0.06

68.23

0.26±0.13

70.78

B1

0.24±0.01

0

0.34±0.02

29.16

0.34±0.02

56.41

0.31±0.01

63.52

0.30±0.01

66.29

B2

0.24±0.02

0

0.34±0.03

29.16

0.35±0.03

55.12

0.31±0.01

63.52

0.30±0.02

66.29

B3

0.23±0.03

4.16

0.31±0.04

35.41

0.30±0.01

61.53

0.30±0.02

64.70

0.28±0.03

68.53

B4

0.24±0.01

0

0.33±0.01

31.25

0.34±0.02

56.41

0.32±0.02

62.35

0.30±0.02

66.29

B5

0.24±0.01

0

0.32±0.01

33.33

0.30±0.01

61.53

0.29±0.02

65.88

0.28±0.01

68.53

B6

0.23±0.01

4.16

0.33±0.02

31.25

0.34±0.02

56.41

0.33±0.01

61.17

0.32±0.02

64.04

B7

0.23±0.01

4.16

0.31±0.02

35.41

0.31±0.02

60.25

0.28±0.02

67.05

0.27±0.01

69.66

B8

0.24±0.02

0

0.33±0.03

31.25

0.34±0.03

56.41

0.33±0.03

61.17

0.32±0.03

64.04

B9

0.24±0.02

0

0.31±0.02

35.41

0.30±0.02

61.53

0.28±0.03

67.05

0.28±0.02

68.53

B10

0.24±0.02

0

0.33±0.03

31.25

0.34±0.03

56.41

0.33±0.03

61.17

0.32±0.03

64.04

B11

0.24±0.02

0

0.34±0.03

29.16

0.35±0.03

55.12

0.31±0.01

63.52

0.30±0.02

66.29

 

 

 


Result and discussion:

Antibacterial activity:

The compounds A1, A2,  A3, A5, A8, B4, B5 ,B6, B7, B8, B9 has  excellent Antibacterial activity against S. aureus, the compounds A1, B4, B5 have shown Antibacterial activity against B. subtilis, while A4, B2, B3, B6, B­7, B8, B9 shows Antibacterial activity against E.coli. when compared with standard Ciprofloxacin.

 

Anti-Inflammatory Activity:

All the compounds were evaluated for Anti-inflammatory activity by Carrageenan Induced Rat hind Paw method. The synthesized compounds A2, A4, A5, A6, A8, B1, B3, B7,and B8 showed better anti-inflammatory activity found comparable with standard drug Ibuprofen (70.78% inhibition)  at the same dose (100µg/kg).

 

REFERENCES:

1.        Maria C. S. Lourenco, Marcus V. N deSouza, Alessandra C Pinheiro, Marcelle de L. Ferreira, Rasnisb B, Goncalves, Thais Cristina M Nogneira, Monica A Peralta, Evaluation of anti-Tubercular activity of nicotinic and isoniazid analogues. ARKIVOC 2007 (xv), 181-191.

2.        Jagtap V. A., Agasimundin Y. S., Jayachandran E. and Sathe B. S. In-Vitro Anti-Inflammatory Activity of 2-Amino-3-(Substituted Benzylidine carbohydrazide) 4,5,6,7 Tetrahydrobenzothiophenes. J. Pharm. Research 2011; 4(2):378-379

3.        Elias G., Rao M N A., Inhibition of albumin denaturation and anti-inflammatory activity of dehydrozingerone and its analogs  Indian J. Exp. Biol; 26: 1988, 540.

4.        Vogel HG, Vogel WH. Drug Discovery and Evaluation Pharmacological Assays. 2nd ed. Berlin: Springer Verlag; 2002: p. 401-55.

 

 


 

 

 

Received on 10.11.2014          Accepted on 12.12.2014        

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Asian J. Pharm. Tech.  2014; Vol. 4: Issue 4, Oct.-Dec., Pg 189-194