https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:10352 Wed 12 May 2021 17:28:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10346 Thu 13 May 2021 00:51:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:64249 100 μg/ml) while the LC50 for Z. mucronata subsp. mucronata equaled 90.27 µg/ml indicated a low level of toxicity. The effects of combining the crude extracts of these plants with eight antibiotics were investigated by means of checkerboard and agar diffusion methods. On using the methanol extract of A. mearnsii, the agar diffusion assay showed that extract-kanamycin combination had zones of inhibition ≥ 20 ± 1.0 mm in all the bacteria tested (100percent), followed by extract chloramphenicol (90percent) > extract-ciprofloxacin = extract-tetracycline (70percent) > extract amoxicillin (60percent) > extract-nalidixic acid (50percent) > extract-erythromycin (40percent) > extract metronidazole (20percent). The checkerboard showed synergistic interaction (61.25percent), additivity/indifference (23.75percent) and antagonistic (15percent) effects. I, therefore, concluded that the antibacterial potentials of the antibiotics were improved and combining natural products with antibiotic could be a potential source of resistance-modifying agents useful against multi-drug resistant bacteria. The influences of these extracts on the ultrastructures, elemental components, protein and lipid leakages of five different bacteria were determined as the possible mechanisms of action of the extracts investigated. The scanning electron microscopy indicated varied ultrastructural changes in the morphology of bacterial cells treated with the extracts. The X-ray microanalysis showed significant differences between the elemental contents of extract-treated and untreated bacteria while lipids and proteins were leaked to a great extent from the extract-treated bacterial strains in comparison with the untreated ones. The possible mechanisms of action of the extracts may include inhibition of a significant step in peptidoglycan assembly, inhibition of metabolic processes, disruption of cell wall and cell membranes resulting in the efflux of lipid and protein in all the bacteria tested. The possible mechanism of action involved in the lipid and protein leakages in the bacterial cells could be attributed to lipid peroxidation and protein oxidation owing to the antioxidant activities of the extracts that were active beyond the protective levels. I concluded that the morphological changes and the observed leakages showed rapid killing, significant membrane depolarization resulting in leakages and efflux of disintegrated cellular materials. In general, this study has justified the ethnotherapeutic importance of A. mearnsii and Z. mucronata subsp. mucronata in the treatment of microbial infections by indicating the possible mechanisms of action of the crude extracts on the tested bacteria.]]> Fri 12 May 2023 15:13:04 SAST ]]>