The in-vitro antibacterial activity of Annona senegalensis, Securidacca longipendiculata and Steganotaenia araliacea - Ugandan medicinal plants.

Background: Nearly all cultures from ancient times to the present day have used plants as a source of medicines. As a result, different remedies tended to develop in different parts of the world. Current strategies to overcome the global problem of antimicrobial resistance include research in finding new and innovative antimicrobials from plants.

Objectives: To determine the antibacterial activity of extracts of Annona senegalensis, Securidacca longipendiculata and Steganotaenia araliacea, plants which are used in Eastern Uganda for the treatment of diarrhea and wound infections.

Methods: The root barks of these plants were collected, sun-dried, pounded using pestles and wooden mortars. Water and methanol extracts were derived and screened. Standard cultures of E. coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 25923 were used in the study. The antibacterial tests used were the agar well diffusion assays. The minimum inhibitory concentrations (MIC) were determined by cylinder plate technique.

Results: Extracts of Annona senegalensis, Steganotaenia araliacea and Securidaca longipendiculata showed activity against Staphylococcus aureus. The methanol extract of Securidaca longipediculata was not inhibitory to S.aureus. Steganotaenia araliacea and Securidaca longipediculata (water) extracts were active against all the bacteria tested. The water and methanol extracts of Annona senegalensis did not show inhibitory activity against E. coli. Of the three bacteria studied, Staphylococcus aureus was the most susceptible to the extracts followed by P. aeruginosa. E. coli was least sensitive to the plant extracts. Annona senegalensis had the lowest MIC against Staphylococcus aureus (62.5 mg/ml); while Steganotaenia araliacea had the highest MIC (250 mg/ml) signifying lower activity.

Conclusions: The root bark extracts of the three plants showed antibacterial activity, justifying their continued use in treatment of bacterial infections.

Recommendations: Further studies are required to isolate and characterise the active phytochemical constituents in the plants. Toxicity studies should be done to determine their safety.