In vitro antioxidant and antibacterial activity of Crude extracts of some freshwater cyanobacteria
| dc.contributor.advisor | Opoku, A.R Osunsanmi, F.O. and Mosa, R.A | |
| dc.contributor.author | Ikhane, Olufemi Akayagboke Albert | |
| dc.date.accessioned | 2024-07-16T11:06:50Z | |
| dc.date.available | 2024-07-16T11:06:50Z | |
| dc.date.issued | 2023 | |
| dc.description | A Thesis submitted to the Faculty of Science, Agriculture and Engineering in fulfilment of the requirements for the Degree of Master of Science in the Department of Biochemistry and Microbiology at the University of Zululand, South Africa [2023]. | |
| dc.description.abstract | Commonly available antibiotics are increasingly becoming ineffective due to the astronomic rise of antimicrobial resistance (AMR). As a result, there is a need for the discovery of new antibiotics and antioxidants from natural products. Cyanobacteria possess a myriad of significant secondary metabolites among which potential antibacterial and antioxidant could be found. The aim of this study was to exploit the potential metabolite reservoir of cyanobacteria towards the development of novel antimicrobial compounds. Freshwater cyanobacteria, Cylindrospermum alatosporum NR125682.1 and Loriellopsis cavenicola NR117881.1, utilized in this study were isolated from Vulindlela area, KwaZulu-Natal, SA. They were propagated on BG-11 media, identified, and characterized through 16S rRNA sequencing. The cyanobacteria were sequentially extracted with hexane, dichloromethane (DCM) and ethanol. The extracts were screened for their antioxidant capacity using DPPH, ABTS, OH* radicals and metal chelating potential. The in silico molecular docking of the major constituents of the extracts against β-lactamase was also evaluated. The in vitro antibacterial potential of the extracts was evaluated using the broth microdilution method against some selected gram-positive and gram-negative clinical bacterial isolates. The effect of the extracts on the bacterial membranes was evaluated using the lactate dehydrogenase assay. The efflux pump inhibitory potential was investigated by measuring the percentage cytoplasmic accumulation of rhodamine. Beta-lactamase inhibitory potential was investigated along with synergistic potential when combined with erythromycin. The ability of the extracts to effect DNA damage was also evaluated. The crude extracts were moderate antioxidants, scavenging free radicals with IC50 range of 6-10 μg/ml and metal chelating efficiency IC50 values ranging from 44-72 μg/ml. Despite the encouraging (-6.6, -6.3 kJmol-1) binding affinity of some of the phytochemicals in the extracts following molecular docking against beta-lactamase, the in vitro inhibition of beta-lactamase indicates that all six extracts were poor inhibitors of the enzyme with a high IC50 value of 5.6 mg/ml. The ethanol crude extract of both isolates was the most efficient with a minimum MIC value of 0.7 mg/ml against the tested resistant bacteria. The ethanol extract of Loriellopsis cavenicola NR117881.1 effectively inhibited efflux pump activity, with up to 60% rhodamine accumulation in the bacteria tested. The extracts effected cell membrane damage on the tested bacteria. The extract also exhibited synergism when combined with erythromycin against some of the tested bacteria. Only the DCM extract of Loriellopsis cavenicola NR117881.1 effected DNA damage. The various bioactivity exhibited by the extracts suggest potential for the development of antibacterial and antioxidant active agents with multiple beneficial effects. | |
| dc.identifier.uri | https://uzspace.unizulu.ac.za/handle/10530/2573 | |
| dc.language.iso | en | |
| dc.publisher | University of Zululand | |
| dc.title | In vitro antioxidant and antibacterial activity of Crude extracts of some freshwater cyanobacteria | |
| dc.title.alternative | freshwater cyanobacteria | |
| dc.type | Thesis |