BACKGROUND: Diseases caused by bacteria remain a major challenge globally and particularly in sub-Saharan Africa.
The plants used in this study have been used in South Africa to treat helminth infections in livestock and humans.
In a previous study we found a correlation between antifungal and anthelmintic activity in some cases. In this study
we examined other potential uses of these thirteen plant species by determining the antibacterial and antioxidant
activity of the leaf acetone extracts.
The antibacterial activity was determined by using a serial microdilution method against Staphylococcus aureus,
Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis. Bioautography was used to determine the
number of antibacterial compounds. The antioxidant activity was determined using the ABTS and DPPH methods.
RESULTS: Maesa lanceolata and Leucosidea sericea with an MIC of 0.02 mg/ml had excellent antibacterial activity
against Enterococcus faecalis and Pseudomonas aeruginosa. There was a poor correlation between antioxidant
activity and antibacterial activity with R2 = 0.143. This is because antibacterial activity is mainly related to non-polar
compounds and antioxidant activity to polar compounds. Maesa lanceolata extracts had a low cytotoxicity with a
selectivity index of 5.2, 2.6, 2.6 and 1.3 for P. aeruginosa, E. faecalis, E. coli and S. aureus respectively. Strychnos mitis
extracts had a therapeutic index of 1.1 for E. coli.
CONCLUSIONS: This study shows that plant extracts of some species used in ethnoveterinary medicine as
anthelmintic may also have excellent antibacterial activity.
MA participated in the design of the study, carried out field work, prepared
the extracts, participated in all assays and wrote the first draft of the
manuscript. VN participated in the design and coordination of the study,
supervised the study and revised the draft manuscript. JNE conceived the
study, participated in the design and coordination of the study, supervised
the study, analysed the data and revised the final manuscript. All authors
read and approved the final manuscript.