Table 8.
Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) (mg/mL) of G. alypum, G. punctata, G. cordifolia and G. meridionalis methanolic aerial parts extracts against tested bacterial strains (mean values, n = 3).
| Bacterial Strains | G. alypum | G. punctata | G. cordifolia | G. meridionalis | Gentamicin a | Verbascoside b |
|---|---|---|---|---|---|---|
| Gram-Positive | ||||||
|
Bacillus cereus ATCC 11778 |
11.36 c 11.36 d |
2.84 c 2.84 d |
11.36 c 11.36 d |
11.36 c n.d. d |
0.0015 c 0.0015 d |
n.d. c n.d. d |
|
Bacillus subtilis ATCC 6633 |
n.d. c n.d. d |
1.89 c 2.84 d |
n.d. c n.d. d |
n.d. c n.d. d |
< 0.0001 c 0.0002 d |
n.d. c n.d. d |
|
Enterococcus faecalis ATCC 29212 |
n.d. c * n.d. d |
n.d. c * 5.68 d |
n.d. c * n.d. d |
n.d. c * n.d. d |
n.d. c * 0.0046 d |
n.d. c * n.d. d |
| Methicillin-Susceptible Staphylococcus aureus (MSSA) | ||||||
|
Staphylococcus aureus ATCC 6538 |
1.42 c 1.89 d |
1.42 c 1.42 d |
2.84 c 3.79 d |
2.84 c 2.84 d |
0.0006 c 0.0008 d |
0.2272 c n.d. d |
|
Staphylococcus aureus ATCC 29213 |
4.73 c 4.73 d |
11.36 c 11.36 d |
7.58 c 11.36 d |
11.36 c 11.36 d |
0.0003 c 0.0007 d |
0.2272 c 0.2272 c |
|
Staphylococcus aureus MFBF 505 |
2.37 c 2.37 d |
1.42 c 1.42 d |
2.84 c 2.84 d |
2.84 c 2.84 d |
n.m. n.m. |
n.m. n.m. |
|
Staphylococcus aureus MFBF 10661 |
1.42 c 1.42 d |
1.42 c 1.42 d |
1.89 c 2.37 d |
1.42 c 1.89 d |
n.m. n.m. |
n.m. n.m. |
|
Staphylococcus aureus MFBF 10666 |
1.42 c 1.42 d |
1.89 c 1.89 d |
1.89 c 1.89 d |
1.42 c 1.42 d |
n.m. n.m. |
n.m. n.m. |
| Methicillin-Resistant Staphylococcus aureus (MRSA) | ||||||
| MRSA MFBF 101 |
1.89 c 2.84 d |
1.42 c 1.42 d |
2.84 c 2.84 d |
2.84 c 2.84 d |
n.m. n.m. |
n.m. n.m. |
| MRSA MFBF 124 |
2.84 c 2.84 d |
2.84 c 2.84 d |
3.31 c 3.79 d |
2.84 c 2.84 d |
n.m. n.m. |
n.m. n.m. |
| MRSA MFBF 154 |
2.84 c 2.84 d |
1.89 c 2.37 d |
2.84 c 2.84 d |
2.84 c 2.84 d |
n.m. n.m. |
n.m. n.m. |
| MRSA MFBF 164 |
2.84 c 2.84 d |
1.42 c 1.89 d |
2.84 c 2.84 d |
3.79 c 3.79 d |
n.m. n.m. |
n.m. n.m. |
| MRSA MFBF 177 |
2.84 c 2.84 d |
2.37 c 2.84 d |
3.79 c 3.79 d |
2.84 c 2.84 d |
n.m. n.m. |
n.m. n.m. |
| Gram-Negative | ||||||
|
Escherichia coli ATCC 10536 |
n.d. c n.d. d |
1.42 c 2.84 d |
n.d. c n.d. d |
n.d. c n.d. d |
0.0001 c 0.0015 d |
0.2272 c n.d. d |
|
Klebsiella pneumoniae MFBF 10402 |
n.d. c n.d. d |
n.d. c n.d. d |
n.d. c n.d. d |
n.d. c n.d. d |
0.0003 c 0.0008 d |
n.d. c n.d. d |
|
Pseudomonas aeruginosa ATCC 27853 |
22.73 c 22.73 d |
n.d. c n.d. d |
n.d. c n.d. d |
n.d. c n.d. d |
0.0011 c 0.0030 d |
0.2272 c n.d. d |
a Positive control, broad-spectrum aminoglycoside antibiotic; b major phenylethanoid of all investigated species; c minimum inhibitory concentrations (MICs) evaluated based on the serial broth microdilution method after detection with 1% (w/v) TTC; d minimum bactericidal concentrations (MBCs) evaluated after agar sub-cultivation; n.d.—growth inhibition not detected with tested concentrations of extract (c = 0.36–22.73 mg/mL for P. aeruginosa, c = 0.18–11.36 mg/mL for other bacterial species); * color change with TTC was not observed; n.m.—not measured.