Doctoral Degrees (Molecular Biology and Human Genetics)
Permanent URI for this collection
Browse
Browsing Doctoral Degrees (Molecular Biology and Human Genetics) by Subject "Anti-infective agents"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
- ItemAntimycobacterial activity of ascidian fungal symbionts(Stellenbosch : Stellenbosch University, 2022-12) Tapfuma, Kudzanai Ian; Mavumengwana, Vuyo; Malgas-Enus, Rehana; Loxton, Andre Gerhard; Allie, Nasiema; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Molecular Biology and Human Genetics.ENGLISH ABSTRACT: Tuberculosis (TB) is an infectious disease which primarily affects the lungs. Treatment of TB is complicated because the causative agent, Mycobacterium tuberculosis, is an intracellular pathogen which infects and kills cells of the innate immune system, while exhibiting intrinsic and extrinsic resistance to many of the currently available antimicrobial agents. A sizeable percentage of TB patients in the world-population are infected by M. tuberculosis strains which are resistant to currently utilized first- and second-line anti-TB drugs. Drug-discovery studies bioprospecting for compounds with novel anti-TB activities are therefore essential in order to control the spread of TB and to prevent a catastrophic pandemic. In this study, extracts from marine fungi were considered for antimycobacterial activity bioprospecting as they are largely underexplored. A total of 46 cultivable fungi were isolated from ascidians and 32 of these fungal isolates were sequenced and consequently identified. Among these fungi, the methanol crude extract from Clonostachys rogersoniana MGK33 was found to possess the highest antimycobacterial activity with minimum inhibitory concentrations of 0.125 and 0.200 µg/mL against Mycobacterium smegmatis mc2 155 and M. tuberculosis H37Rv, respectively. Untargeted metabolite profiling of the crude extract from C. rogersoniana MGK33 revealed the presence of bionectin F (among other compounds) which has previously been shown to possess antimicrobial activity in other studies. In silico molecular docking and simulation experiments in this study showed that bionectin F is a potential inhibitor of M. tuberculosis β-ketoacyl-ACP reductase (MabA). An attempt was then made to generate novel agents that would be composed of nanoparticles surface functionalized with the bioactive fungal extract from C. rogersoniana MGK33. In particular, mono-metallic SPIONs were synthesized using the co-precipitation method and then surface modified to produce bi-metallic superparamagnetic iron oxide nanoparticles (SPIONs) using nickel, zinc, gold, copper and silver, to produce Ni-SPIONs, Zn-SPIONs, Au-SPIONs, Cu-SPIONs and Ag-SPIONs. Functionalization was then performed using the MGK33 extract to produce Ni-SPIONs@MGK33, Zn-SPIONs@MGK33, Au-SPIONs@MGK33, Cu SPIONs@MGK33 and Ag-SPIONs@MGK33. Among these agents, Cu-SPIONs and Ag SPIONs were found to exhibit the strongest antimycobacterial activity, comparatively stronger than that of the counterparts, Cu-SPIONs@MGK33 and Ag-SPIONs@MGK33. In an experiment involving the treatment of RAW 264.7 macrophage cells infected with M. smegmatis mc2 155, the MGK33 extract exhibited the highest early apoptosis activity (9.61%), followed by Cu-SPIONs@MGK33 (3.34%), both agents tested at 1.96 µg/mL for 24 hours. The MGK33 extract further showed strong antimycobacterial activity against intracellular M. smegmatis mc2 155, compared with the nanoparticles synthesized in this study. Results in this study led to the conclusion that the marine fungus, C. rogersoniana MGK33 is a prolific source of compounds with antimycobacterial and immunomodulatory activity, and that further studies should be done to develop Cu-SPIONs and Ag-SPIONs into lead agents for anti-TB drug development.