Seasonal Variation in Essential Oils Composition and the Biological and Pharmaceutical Protective Effects of Mentha longifolia Leaves Grown in Tunisia
Table 4
Season variation in antibacterial activity of M. longifolia essential oils against the bacterial strains tested. E: essential oil extracted at winter season; E: spring essential oil.
(a)
Bacterial strains
Extracts
Ml EtOcF
Ml EtOH-H2OE
E
E
Genta
Diameter of inhibition zone (mm)
Gram +
B. subtilis ATCC 6633
27±0.1
14±0.2
26.3±0.0
11±0.5
20±0.2
B. cereus ATCC 14579
17±0.3
12±0.8
26±0.2
14±0.6
20±0.4
S. aureus ATCC 25923
25±0.0
13±0.6
24.9±0.3
14.6±0.5
25±0.8
S. epidemis ATCC 12228
24±0.6
20±0.3
14±0.4
13±0.0
20±0.5
E. faecalis ATCC 29212
18±0.1
0
20±0.3
12±0.1
12±0.2
M. luteus ATCC 1880
21±0.4
18±0.5
15±0.6
15±0.6
20±0.7
L. monocytogenes (food isolate 2132)
19±0.2
18±0.1
13.16 ±0.4
12.60 ±0.9
15±0.0
Gram-
S. enteritidis (food isolate)
24±0.2
14±0.3
10±0.12
11.3±0.1
18±0.8
K. pneumoniae ATCC 10031
18±0.2
15±0.1
16.6±0.3
16±0.5
12±0.5
(b)
Minimum inhibitory concentrations (MIC) and Minimum bactericidal concentration (MBC) (mg/ml)
MIC
MBC
MIC
MBC
MIC
MBC
MIC
MBC
Gram +
B. subtilis ATCC 6633
0.039
0.078
0.078
0.156
0.078
5.0
0.156
5.0
-
B. cereus ATCC 14579
0.039
0.625
0.156
5.0
0.156
0.156
0.312
5.0
-
S. aureus ATCC 25923
0.625
1.25
2.5
5.0
0.312
0.625
0.625
0.625
-
S. epidemis ATCC 12228
0.156
0.312
2.5
2.5
5.0
10
5.0
10
-
E. faecalis ATCC 29212
1.25
1.25
2.5
2.5
0.078
1.25
0.625
10
-
M. luteus ATCC 1880
0.312
1.25
2.5
5.0
5.0
10
5.0
10
-
L. monocytogenes (food isolate 2132)
0.156
0.625
2.5
5.0
1.25
5.0
1.25
5.0
-
Gram-
S. enteritidis (food isolate)
0.078
0.625
0.312
5.0
2.5
5.0
2.5
5.0
-
K. pneumoniae ATCC 10031
0.312
1.25
0.312
5.0
2.5
2.5
2.5
2.5
-
Genta: gentamicin was used as a standard antibiotic at a concentration of 15 μg/well; essential oil concentration: 15 μl/well; extract concentration: 2.5 mg/ml. (-): not active (0 mm). Values in the same line with different subscript (a > b > c>d) are significantly different within season ( <0.05).
