Green synthesis of novel coumarin derivatives via grinding approach and their antimicrobial evaluation

Figures & data

Figure 1. ¹H NMR spectrum of compound 2.

Scheme 1. Synthesis of thiazole derivatives 2, 3.

Figure 2. ¹H NMR spectrum of compound 5a.

Scheme 2. Synthesis of thiazole derivatives 4–7.

Scheme 3. Synthesis 1,3,4-thiadiazole 9 and thiophenes 10, 12.

Table 1. In vitro preliminary antimicrobial activity of the newly synthesized compounds against pathogenic bacteria and fungi.

Compd. no	Inhibition zone diameter in mm
	B. pumilis	S. faecalis	E. coli	E. cloacae	S. cerevisiae	C. albicans
2	17	20	16	13	22	15
4a	13	10	19	17	13	18
4b	17	22	19	15	13	18
5a	20	17	15	22	18	12
5b	21	16	18	24	17	19
6	18	14	18	18	14	19
7	24	20	22	19	21	18
8	12	16	17	13	11	16
9	16	19	17	20	13	17
10	14	18	20	16	19	15
11	18	20	22	17	14	17
12	23	20	20	18	17	19
Penicillin G	26	23	–	–	–	–
Ciprofloxacin	–	–	28	26	–	–
Ketoconazole	–	–	–	–	20	24

Table 2. In vitro MIC and MBC for the newly synthesized compounds.

Compd. no	MIC (µg/ml)				MBC (µg/ml)
	B. pumilis	S. faecalis	E. coli	E. cloacae	B. pumilis	S. faecalis	E. coli	E. cloacae
2	15.6	31.3	1.95	62.5	62.5	125	15.6	250
4a	3.91	7.81	3.91	15.6	31.3	62.5	31.3	62.5
4b	7.81	15.6	3.91	31.3	31.3	31.3	31.3	125
5a	31.3	7.81	7.81	7.81	125	62.5	62.5	62.5
5b	31.3	62.5	31.3	15.6	62.5	31.3	125	125
6	15.6	15.6	15.6	31.3	62.5	62.5	62.5	62.5
7	1.95	3.91	1.95	7.81	15.6	31.3	7.81	31.3
8	3.91	7.81	7.81	31.3	31.3	31.3	31.3	125
9	15.6	31.3	31.3	7.81	62.5	125	125	62.5
10	31.3	31.3	3.91	15.6	125	62.5	31.3	31.3
11	1.95	15.6	31.3	7.81	15.6	62.5	125	125
12	7.81	31.3	15.6	3.91	31.3	125	62.5	62.5
Penicillin G	0.125	3.91	–	–	0.5	15.61	–	–
Ciprofloxacin	–	–	0.16	0.250	–	–	0.5	1

Table 3. In vitro MIC and MFC of the synthesized compounds.

Compd. no	MIC (µg/ml)		MFC (µg/ml)
	S. cerevisiae	C. albicans	S. cerevisiae	C. albicans
2	31.3	62.5	125	125
4a	62.5	62.5	250	250
4b	31.3	125	250	500
5a	7.81	31.3	62.5	125
5b	15.6	15.6	125	62.5
6	62.5	62.5	500	250
7	3.91	15.6	62.5	62.5
8	15.6	31.3	62.5	125
9	62.5	15.6	250	62.5
10	15.6	31.3	125	125
11	31.3	125	125	500
12	62.5	15.6	500	62.5
Ketoconazole	0.5	0.125	2	0.5