Thermal solvent-free synthesis of chromonyl chalcones, pyrazolines and their in vitro antibacterial, antifungal activities

Figures & data

Table 1.  Antibacterial activity of compounds 3a-4f.

Compounds	Gram-positive bacteria						Gram-negative bacteria
	Staphylococcus pyogenes			MRSA*			Pseudomonas aeruginosa			Klebsiella pneumoniae			Escherichia coli
	Zone	MIC	MBC	Zone	MIC	MBC	Zone	MIC	MBC	Zone	MIC	MBC	Zone	MIC	MBC
3a	13.5 ± 0.4	25	100	13.4 ± 0.4	25	50	15.1 ± 0.6	50	100	12.6 ± 0.2	25	50	13.3 ± 0.2	25	100
3b	11.4 ± 0.5	25	50	11.1 ± 0.5	50	100	13.2 ± 0.4	25	50	10.7 ± 0.5	50	100	11.1 ± 0.5	25	50
4a	21.5 ± 0.2	25	100	20.6 ± 0.4	50	100	26.3 ± 0.6	50	100	21.5 ± 0.2	50	>100	22.4 ± 0.5	50	>100
4b	20.3 ± 0.4	25	100	19.8 ± 0.3	50	100	22.4 ± 0.2	50	>100	18.4 ± 0.5	50	>100	19.9 ± 0.4	50	100
4c	18.1 ± 0.5	25	100	17.3 ± 0.4	25	>100	20.1 ± 0.4	100	>100	16.1 ± 0.5	50	>100	17.5 ± 0.3	50	>100
4d	15.2 ± 0.4	50	100	14.5 ± 0.2	50	100	12.2 ± 0.3	50	>100	14.5 ± 0.4	100	>100	15.5 ± 0.3	100	>100
4e	10.4 ± 0.4	50	100	10.1 ± 0.3	50	>100	12.2 ± 0.2	50	>100	10.5 ± 0.3	50	>100	11.1 ± 0.4	50	>100
4f	15.2 ± 0.2	50	100	10.7 ± 0.4	50	100	15.2 ± 0.3	50	100	13.3 ± 0.2	50	100	11.8 ± 0.5	50	>100
Standard	23.0 ± 0.2	12.5	12.5	22.0 ± 0.2	6.25	12.5	32.0 ± 0.3	12.5	25	19.0 ± 0.2	6.25	25	27.0 ± 0.2	6.25	12.5
DMSO	–	–	–	–	–	–	–	–	–	–	–	–	–	–	–

Diameter of zone of inhibition (mm), MIC and MFC results of compounds 3a-4f and positive control griseofulvin.Positive control (Standard); ciprofloxacin and negative control (DMSO) measured by the Halo Zone Test (unit, mm). *Methicillin resistant S. aureus (MRSA +ve). MIC (µg/mL), minimum inhibitory concentration, i.e., the lowest concentration of the compound to inhibit the growth of bacteria completely; MBC (µg/mL), minimum bactericidal concentration, i.e., the lowest concentration of the compound for killing the bacteria completely.

Table 2.  Antifungal activity of compounds 3a-4f.

Compounds	Candida albicans			Aspergillus fumigatus			Trichophyton mentagrophytes			Penicillium marneffei
	Zone	MIC	MFC	Zone	MIC	MFC	Zone	MIC	MFC	Zone	MIC	MFC
3a	22.2 ± 0.4	12.5	50	19.7 ± 0.3	12.5	50	15.8 ± 0.9	25	100	14.3 ± 0.2	25	50
3b	21.3 ± 0.3	12.5	25	19.6 ± 0.4	25	100	15.4 ± 0.2	12.5	50	12.9 ± 0.3	25	50
4a	20.1 ± 0.3	25	100	18.1 ± 0.2	25	100	14.3 ± 0.3	25	100	11.7 ± 0.2	50	100
4b	20.1 ± 0.3	25	100	17.2 ± 0.5	50	100	13.7 ± 0.4	50	100	10.1 ± 0.4	50	100
4c	19.8 ± 0.5	50	100	17.6 ± 0.6	50	100	12.1 ± 0.3	50	100	10.3 ± 0.6	25	100
4d	18.1 ± 0.3	25	100	16.5 ± 0.4	25	100	11.7 ± 0.5	50	100	9.2 ± 0.4	50	100
4e	17.9 ± 0.3	50	100	15.5 ± 0.5	50	>100	10.4 ± 0.2	50	>100	8.9 ± 0.3	50	100
4f	19.4 ± 0.5	50	100	17.1 ± 0.6	100	>100	12.1 ± 0.4	50	100	10.3 ± 0.6	50	>100
Standard	30.0 ± 0.2	6.25	25	27.0 ± 0.2	12.5	12.5	24.0 ± 0.3	6.25	25	20.0 ± 0.5	12.5	25
DMSO	–	–	–	–	–	–	–	–	–	–	–	–

Diameter of zone of inhibition (mm), MIC and MFC results of compounds 3a-4f and positive control griseofulvin. Positive control (griseofulvin) and negative control (DMSO) measured by the Halo Zone Test (Unit, mm). MIC (µg/mL), minimum inhibitory concentration, i.e., the lowest concentration of the compound to inhibit the growth of fungi completely; MFC (µg/mL), minimum fungicidal concentration, i.e., the lowest concentration of the compound for killing the fungi completely.

Scheme 1.  Formation of chalcones 3a-b and their reaction with different hydrazines to give compounds 4a-f.