Synthesis, antimicrobial and antimycobacterial evaluation of [2-(substituted phenyl)-imidazol-1-yl]-pyridin-3-yl-methanones

Figures & data

Table 1.  Physicochemical characteristics and antimycobacterial activities of synthesized [2-(substituted phenyl)-imidazol-1-yl/benzimidazole-1-yl]-pyridin-3-yl-methanones.

Comp.	R1	R2	R3	R4	Mol. formula	M. wt.	m.p. (°C)	Rf value*	% yield	MIC (µg/ml)
1	H	H	H	H	C15H11N3O	249.27	79–81	0.83	50.76	>25.0
2	CH3	CH3	H	H	C17H15N3O	277.33	219–221	0.32	42.50	25.0
3	CH3	H	H	CH3	C17H15N3O	277.33	209–211	0.15	56.80	25.0
4	Cl	H	H	H	C15H10ClN3O	283.72	94–96	0.15	68.75	12.5
5	H	H	Cl	H	C15H10ClN3O	283.72	119–121	0.80	54.76	6.25
6	H	Cl	H	H	C15H10ClN3O	283.72	99–101	0.74	36.80	12.5
7	H	H	Br	H	C15H10BrN3O	328.17	>260	0.32	35.78	6.25
8	H	H	NO2	H	C15H10N4O3	294.27	49–51	0.58	45.98	3.13
9	NO2	H	H	H	C15H10N4O3	294.27	189–191	0.53	65.70	6.25
10	H	NO2	H	H	C15H10N4O3	294.27	219–221	0.18	43.76	6.25
11	COOH	H	H	H	C16H11N3O3	293.28	145–147	0.15	56.30	>25.0
12	Cl	H	H	H	C19H12N3OCl	333.83	84–86	0.95	39.13	3.13
13	H	H	Cl	H	C19H12N3OCl	333.83	224–226	0.48	47.82	3.13
14	H	Cl	H	H	C19H12N3OCl	333.83	149–151	0.59	73.91	6.25
15	H	H	OH	H	C19H13N3O2	315.37	64–66	0.15	11.20	25
16	H	H	NO2	H	C19H12N4O3	344.30	244–246	0.22	48.59	1.56
17	H	NO2	H	H	C19H12N4O3	344.30	239–241	0.31	70.09	3.13
18	NO2	H	H	H	C19H12N4O3	344.30	49–51	0.90	14.95	3.13
19	COOH	H	H	H	C20H13N3O3	343.41	139–141	0.13	45.08	25
20	OCH3	H	H	H	C20H15N3O2	329.39	99–101	0.90	14.20	25
Isoniazid										0.10
Ethambutol										1.56
Ciprofloxacin										3.13

MIC, minimum inhibitory concentration.

*Toluene:Chloroform (7:3).

^aReported in Reference 16.

Scheme 1.  Synthetic route followed to obtain target compounds

Table 2.  Antimicrobial activity of synthesized [2-(substituted phenyl)-imidazol-1-yl]-pyridin-3-yl-methanones.

Comp.	MIC (µM/ml)
	S. aureus	B. subtilis	E. coli	C. albicans	A. niger
1	0.012	0.003	0.003	0.025	0.050
2	ND	ND	ND	0.022	0.005
3	ND	ND	ND	0.005	0.005
4	0.044	0.044	0.044	0.022	0.044
5	0.022	0.044	0.006	0.022	0.044
6	0.044	0.044	0.011	0.342	0.044
7	ND	ND	ND	0.004	0.019
8	0.010	0.010	0.040	0.020	0.040
9	0.040	0.002	0.040	0.020	0.040
10	0.013	0.005	0.002	0.025	0.025
11	0.002	0.002	0.002	0.020	0.040
Ciprofloxacin	0.004	0.004	0.004	—	—
Fluconazole	—	—	—	0.005	0.005

MIC, minimum inhibitory concentration; ND, not detected.

Figure 1.  Structural requirements for the antimicrobial and antimycobacterial activity of [2-(substituted phenyl)-imidazol-1-yl]-pyridin-3-yl-methanones.

Table 3.  MBC/MFC of [2-(substituted phenyl)-imidazol-1-yl]-pyridin-3-yl-methanones.

Comp.	MBC/MFC(µM/ml)
	S. aureus	B. subtilis	E. coli	C. albicans	A. niger
1	0.025	0.025	0.025	0.100	0.400
2	ND	ND	ND	0.090	0.360
3	ND	ND	ND	0.045	ND
4	0.352	0.352	0.352	0.352	ND
5	0.176	0.352	0.044	0.088	0.176
6	0.352	0.352	0.088	ND	ND
7	ND	ND	ND	0.076	0.019
8	ND	ND	0.169	0.169	0.169
9	0.169	0.169	0.084	0.169	ND
10	0.338	0.006	0.003	0.169	ND
11	0.021	0.021	0.021	0.09	ND

MBC/MFC, minimum bactericidal/fungicidal concentration; ND, not detected.