Antibacterial Activity
Most of the research conducted at the Phytomedicine Programme comprises stud-
ies on the antibacterial activity of plants. This is primarily a consequence of the de-
velopment of the rapid and reproducible serial dilution method [39] used for ob-
taining MIC values of plant extracts against bacterial species. As stated earlier, ace-
tone is routinely selected as a solvent to prepare extracts for the initial screening
process as this solvent among several tested was found to yield the best results with
reference to quantity and diversity of compounds extracted, number of inhibitors
extracted, toxicity in a bioassay, and ease of removal of solvent among other factors
[33]. Bioautographic techniques [41, 45] as described earlier are also employed to
estimate the number and Rf values of antibacterial constituents in a plant extract of
interest.
The test organisms we routinely employ in the preliminary screening of plant ex-
tracts for antibacterial activity are the Gram-positive Enterococcus faecalis (ATCC
29212) and Staphylococcus aureus (ATCC 29213) and the Gram-negative Escherichia
coli (ATCC 27853) and Pseudomonas aeruginosa (ATCC 25922). These ATCC refer-
ence strains are recommended by the National Committee for Clinical Laboratory
Standards (NCCLS), Villanova, Pennsylvania, USA, for antibacterial testing [46]. We
have recently included a strain of methicillin-resistant Staphylococcus aureus and
Mycobacterium smegmatis in the range of bacteria against which activity is tested.
A plethora of publications have reported the antibacterial activity of South Afri-
can plant extracts and compounds isolated from them using bioassay-directed frac-
tionation (see, for example, refs [47–56]). There is a great deal of ongoing research
in this field and much useful and interesting information is being generated.
108 5 Plant Extracts Used to Manage Bacterial, Fungal, and Parasitic Infections in Southern Africa
Most of the research conducted at the Phytomedicine Programme comprises stud-
ies on the antibacterial activity of plants. This is primarily a consequence of the de-
velopment of the rapid and reproducible serial dilution method [39] used for ob-
taining MIC values of plant extracts against bacterial species. As stated earlier, ace-
tone is routinely selected as a solvent to prepare extracts for the initial screening
process as this solvent among several tested was found to yield the best results with
reference to quantity and diversity of compounds extracted, number of inhibitors
extracted, toxicity in a bioassay, and ease of removal of solvent among other factors
[33]. Bioautographic techniques [41, 45] as described earlier are also employed to
estimate the number and Rf values of antibacterial constituents in a plant extract of
interest.
The test organisms we routinely employ in the preliminary screening of plant ex-
tracts for antibacterial activity are the Gram-positive Enterococcus faecalis (ATCC
29212) and Staphylococcus aureus (ATCC 29213) and the Gram-negative Escherichia
coli (ATCC 27853) and Pseudomonas aeruginosa (ATCC 25922). These ATCC refer-
ence strains are recommended by the National Committee for Clinical Laboratory
Standards (NCCLS), Villanova, Pennsylvania, USA, for antibacterial testing [46]. We
have recently included a strain of methicillin-resistant Staphylococcus aureus and
Mycobacterium smegmatis in the range of bacteria against which activity is tested.
A plethora of publications have reported the antibacterial activity of South Afri-
can plant extracts and compounds isolated from them using bioassay-directed frac-
tionation (see, for example, refs [47–56]). There is a great deal of ongoing research
in this field and much useful and interesting information is being generated.
108 5 Plant Extracts Used to Manage Bacterial, Fungal, and Parasitic Infections in Southern Africa
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