In vitro antibacterial activity and in vivo therapeutic effect of Sesbania grandiflora in bacterial infected silkworms

Figures & data

Table 1. Bacteria used in in vitro antibacterial study.

Bacterial strains	Gram stain	Drug sensitivity	Type
Staphylococcus aureus (MSSA1)	Positive	Sensitive	Facultative
S. aureus (MRSA3)	Positive	Resistant (methicillin)	Facultative
S. aureus (MRSA4)	Positive	Resistant (methicillin)	Facultative
S. aureus (MRSA6)	Positive	Resistant (methicillin)	Facultative
S. aureus (MRSA8)	Positive	Resistant (methicillin)	Facultative
S. aureus (MRSA9)	Positive	Resistant (methicillin)	Facultative
S. aureus (MRSA11)	Positive	Resistant (methicillin)	Facultative
S. aureus (MRSA12)	Positive	Resistant (methicillin)	Facultative
Bacillus subtilis JCM2499	Positive	Sensitive	Facultative
B. cereus JCM 20037	Positive	Sensitive	Aerobic
Streptococcus sanguinis	Positive	Sensitive	Facultative^a
Strep. pneumoniae	Positive	Sensitive	Facultative^a
Strep. agalactiae	Positive	Sensitive	Facultative^a
Strep. pyogenes	Positive	Sensitive	Aerobic^a
Listeria monocytogenes	Positive	Sensitive	Facultative^a
Enterococcus faecalis EF1	Positive	Sensitive	Facultative^a
E. faecalis EF5 (VRE)	Positive	Resistant (vancomycin)	Facultative^a
Escherichia coli w3110	Negative	Sensitive	Facultative
Pseudomonas aeruginosa PA01	Negative	Sensitive	Facultative

^a Fastidious bacteria.

Table 2. MIC of the extracts and the standard drugs.

	MIC
Bacterial strains	HXF (mg/mL)	CFF (mg/mL)	EAF (mg/mL)	Vancomycin (μg/mL)	Gentamicin (μg/mL)
MSSA1	50	100	1.6	0.5	1
MRSA3	25	25	1.6	1	128
MRSA4	50	50	1.6	1	128
MRSA6	25	25	1.6	1	128
MRSA8	50	50	1.6	1	128
MRSA9	100	25	1.6	1	128
MRSA11	50	25	1.6	1	128
MRSA12	50	50	1.6	1	0.1
B. subtilis JCM2499	50	50	0.8	0.3	0.1
B. cereus JCM 20037	25	25	0.8	0.3	0.5
Strep. sanguinis	3.1	1.6	1.6	1	4
Strep. pneumoniae	100	100	1.6	1	4
Strep. agalactiae	100	50	1.6	1	4
Strep. pyogenes	1.6	6.2	1.6	1	4
L. monocytogenes	100	50	3.1	2	0.3
E. faecalis EF1	25	100	1.6	1	16
VRE	25	50	0.4	128	128
E. coli w3110	100	200	6.2	>128	0.5
P. aeruginosa PA01	100	200	3.1	>128	8

Figure 1. Survival of silkworms injected with the sequentially fractionated extracts of S. grandiflora bark from hexane (HXF) (▪), chloroform (CFF) (▴), and ethyl acetate (EAF) (•). After injection, all silkworms were kept at 27 °C for 24 h. Numbers of surviving silkworms were counted.

Figure 2. Survival curve of silkworms infected with S. aureus and injected with saline (▪), 95 μg of EAF (•), and 5 μg of vancomycin (▴). Significant difference was determined by log-rank test (p < 0.05).

Figure 3. Qualitative HPLC chromatogram of EAF (A) and standard gallic acid (B), detected at 280 nm.

Figure 4. Preparative HPLC consequences of the EAF detected at 210 nm and antibacterial activity of each 2-min eluent fraction. The line represents the intensity of peaks (left axis) whereas the column represents antibacterial activity (right axis).

Figure 5. Antibacterial activity of EAF (unseparated extract), whole fraction (total of eluent fractions which were separated from EAF), and different active fractions from the preparative HPLC; fraction 9 (Fr.9), fraction 16 (Fr.16), fraction 17 (Fr.17), and fraction 18 (Fr.18) (getting individually each 2 min eluent fractions which separated from EAF).