an investigation into the antibacterial activities of medicinal plants ...

The lowest MIC’s of B. frutescens and L. leonurus were higher for Gram-positive
bacterial strains than for the Gram-negative bacterial strains (Table 10). The lowest
MIC’s of M. major and Z. aethiopica were higher for the Gram-negative bacterial
strains. The highest MIC’s of all the plants were higher for the Gram-negative
bacterial strains than for the Gram-positive bacterial strains.
The highest MIC’s of the plant extracts against the Gram-negative bacterial strains
were the same as the undiluted plant extract concentrations. Therefore some Gramnegative
bacterial strains were only inhibited in the initial wells of the microtitre plates
containing undiluted plant extracts.
TABLE 10
The lowest and highest MIC’s for each medicinal plant extract in the
microtitre plate assay
Medicinal
Plants:
B. frutescens Acet
Extracts:
Undiluted
Extract
(mg/ml)
0.51
MIC’s (mg/ml) in microtitre plate assay.
Gram +ve bacteria: Gram –ve bacteria:
Low. High. Low. High.
0.13 0.13 0.06 0.51
MeOH
0.51
0.26
0.20
0.06
0.51
Aqu.
0.43
0.22
0.43
0.05
0.43
L. leonurus Acet
1.11
0.07
0.56
0.02
1.11
MeOH
1.05
0.07
1.05
0.02
1.05
Aqu
1.19
0.07
1.19
0.07
1.19
M. major Acet
2.17
0.03
0.03
0.03
2.17
MeOH
1.89
0.03
0.12
0.03
1.89
Aqu
1.66
0.03
0.21
0.05
1.66
Z. aethiopica Acet
1.00
0.02
1.00
0.03
1.00
MeOH
1.09
0.14
0.55
0.27
1.09
Aqu
0.62
0.01
0.62
0.04
0.62
Low.: Lowest;
High.: Highest; Acet: acetone; Aqu: Aqueous; MeOH: Methanol
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