Synthesis, characterization and in vitro antimicrobial evaluation of new compounds incorporating oxindole nucleus

Figures & data

Table 1.  Antimicrobial screening results of the tested compounds.

Compounds (50 µg/mL)	Inhibition zone diameter (mm)
	E. coli	S. dysenterie	S. aureus	B. cereus	A. flavus	C. albicans
2a	21	20	20	21	19	20
3	23	25	22	23	19	20
4a	27	27	31	25	19	21
4b	23	23	31	32	20	22
5	32	30	29	25	19	21
6a	20	19	16	20	17	19
6b	21	23	17	23	18	18
7b	17	20	19	19	16	18
9b	25	25	26	22	18	19
11a	23	28	21	19	20	21
11b	21	28	18	19	18	20
11c	20	25	18	18	18	19
12a	24	27	23	23	21	23
12b	22	25	25	19	22	23
13	19	20	15	18	15	17
Sulphamethoxazole (10 µg/mL)	38	35	30	38	^a	^a
Fluconazole (10 µg/mL)	^a	^a	^a	^a	25	27

^aNot tested.

Table 2.  MIC (µg/mL) results of the tested compounds.

Compounds	MIC values (µg/mL)
	E. coli	S. dysenterie	S. aureus	B. cereus	A. flavus	C. albicans
2a	10	10	10	10	15	15
3	10	10	10	10	15	15
4a	5	5	5	1	15	15
4b	5	10	10	5	10	5
5	5	5	5	10	10	10
6a	10	15	15	15	10	5
6b	10	15	15	15	20	15
7b	15	10	15	10	20	15
9b	10	15	15	10	20	15
11a	10	5	10	10	10	10
11b	10	5	10	10	10	10
11c	15	1	15	15	10	15
12a	10	10	10	10	15	10
12b	10	10	10	10	15	10
13	10	15	10	10	15	10
Sulphamethoxazole (10 µg/mL)	2.5	2.5	2.5	2.5	^a	^a
Fluconazole (10 µg/mL)	^a	^a	^a	^a	2.5	2.5

Scheme 1.  Synthesis of the target compounds 2_a,b, 3 and 4_a–c. (i) N-Aminophthalimide, (ii) 1H-benzoimidazol-2-amine and (iii) 4-amino-N-(5-methylisoxazol-3-yl) benzenesulphonamide.

Scheme 2.  Synthetic pathway for target compounds 5, 6_a,b and 7_a,b. (i) Benzylamine, (ii) n-propylamine and (iii) piperidine.

Scheme 3.  Synthetic pathway for target compounds 9_b,c, 10, 11_a–c, 12_a,b and 13. (i) Phenacyl chloride, (ii) acetylacetone, (iii) 4-hydroxy-3-methoxybenzaldehyde (vanillin) and (iv) thiosemicarbazide.

Scheme 4.  Mechanism for the synthesis of target compound 13.