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

The extracts of L. leonurus inhibited four [no.’s 1 – 4] of the five K. pneumoniae
strains. All the strains of P. aeruginosa were inhibited by the extracts of L. leonurus
except strain [no. 1] with the aqueous extract and strain [no. 2] with the methanol and
acetone extracts. Only A. baumanii strain [no. 2] was inhibited by all three extracts of
L. leonurus and strain [no. 4] was inhibited by the methanol & acetone extracts
(Table 9b).
M. major was the only plant that displayed antibacterial activity in all three extracts
against all the Gram-positive and Gram-negative bacterial strains (Table 9b).
The lowest MIC value of M. major for Gram-positive bacterial strains was 0.03 mg/ml
in the aqueous extract against S. aureus strains [no.’s 1, 2 & 4] and MRSA strains [1
– 4]. The MIC of 0.12 mg/ml in the methanol extract of M. major was the highest MIC
against the Gram-positive bacterial strains, S. aureus strains [no.’s 3 & 4].
The lowest MIC value (0.03 mg/ml) of M. major against P. aeruginosa strains was in
the acetone extract against strain [no. 2] and the highest MIC value (1.89 mg/ml) was
in the methanol extract against strain [no. 3]. The lowest MIC value of the methanol
extract of M. major was 0.03 mg/ml against A. baumanii strain [no. 1]. The highest
MIC (1.66 mg/ml) of M. major against A. baumanii strains was in the aqueous extract
against strain [no. 3]. The strains of K. pneumoniae displayed the highest (1.66
mg/ml) and lowest (0.05 mg/ml) MIC values of M. major against strain [no. 1] and
strain [no. 4], respectively.
The methanol extracts of Z. aethiopica inhibited all the S. aureus strains [no.’s 1 – 4]
and none of the MRSA strains. The aqueous extracts of Z. aethiopica only inhibited
S. aureus [no. 3] and MRSA [no. 1] with MIC’s of 0.01 mg/ml and 0.62 mg/ml,
respectively. In comparison to the other plants, the aqueous extract of Z. aethiopica
had the lowest MIC of 0.01 mg /ml.
Only one [no. 2] of the three P. aeruginosa strains was inhibited by the methanol
(1.09 mg/ml) and aqueous (0.62 mg/ml) extracts. The acetone extracts of Z.
aethiopica inhibited two P. aeruginosa strains [no.’s 2 & 3] with MIC’s of 1.00 mg/ml
and 0.25 mg/ml, respectively. Only one [strain no. 1] of the five A. baumanii strains
was inhibited by the extracts of Z. aethiopica (Table 9a & 9b). The lowest and
highest MIC’s of Z. aethiopica against Gram-negative bacterial strains were 0.03
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