Antifungal activity of antimicrobial polymers created with peptides from the tyrothricin complex
| dc.contributor.advisor | Rautenbach, Marina | en_ZA |
| dc.contributor.author | Mitha, Priyata | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Science. Dept. of Biochemistry. | en_ZA |
| dc.date.accessioned | 2024-02-29T11:15:13Z | |
| dc.date.accessioned | 2024-04-26T15:08:24Z | |
| dc.date.available | 2024-02-29T11:15:13Z | |
| dc.date.available | 2024-04-26T15:08:24Z | |
| dc.date.issued | 2024-03 | |
| dc.description | Thesis (MSc)--Stellenbosch University, 2024. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: The global burden posed by the lack of effective antifungal agents in addressing conditions like vulvovaginal candidiasis (VVC), diaper dermatitis, and nosocomial infections, caused by Candida species, has prompted an urgent need for innovative interventions. The increasing resistance to current antifungal agents further highlights the urgency of this issue. To address these challenges, the exploration of novel solutions or modifications to existing applications is paramount. In this context, antifungal peptides (AFPs) have emerged as promising candidates. This study specifically focuses on investigating anti-Candida activity, with a particular emphasis on the tyrocidines (Trcs), a natural cyclodecapeptide antibiotic complex. These peptides are considered good potential candidates for further development due to their broad-spectrum activity against bacteria, fungi, viruses, and parasites, as well as their inherent ability to adhere to various materials. Recent studies have indicated that the peptide adopts two major self-assembly modes depending on its surrounding environment, and the potent antibacterial activity of the peptide is relatively non- selective in terms of the type of material being functionalised. This study aimed to explore the effect of different solvent systems and Trc peptide complexes on anti-Candida activity of Trc-functionalised materials, as well as the biophysical tracking of peptide self-assembly and material binding. The investigated materials include polystyrene plastic and cellulose filter paper (used as controls), viscose and polypropylene sheets/wipes. The Trc mixture, Phe-rich and Trp-rich peptide complexes were formulated in four solvents: acetonitrile (ACN), methanol (MeOH), ethanol (EtOH) and isopropanol (IPA). Optimisation studies by assessing the target cell metabolism over time revealed that EtOH promotes good material adherence and effective antifungal activity for the Trc mixture and Phe-rich complex, while MeOH and IPA have similar effects on the Phe-rich and Trp-rich peptide complexes. The robustness and stability of the functionalised materials were assessed through a series of washing steps. These findings highlighted the significance of amino acid composition in the optimal peptide deposition onto the materials. Testing an industry-derived method for material treatment led to the conclusion that the average polarity of the peptide complex, solvent system, and the material each play a role. The Trc mixture and Phe-rich peptides associated more readily with the hydrophobic polystyrene, while the more polar Trp-rich peptide complex associated readily to the more polar cellulose and viscose. Furthermore, the viscose material allows for even distribution of the peptide, resulting in potent antifungal activity. Furthermore, the link between surface-derived antifungal activity and biophysical properties of the peptides in the different ethanolic solutions during deposition on materials was assessed by observing changes in Trp and Tyr fluorescence. This provided insight into the impact of peptide conformation in solution and its binding to a specific material on antifungal activity. This study indicated that peptide oligomers, driven by hydrophobic interactions and aromatic stacking, lead to the assembly of metastable oligomers that are crucial for material association and antifungal activity. In aqueous solvents, water propelled the formation of hydrophobic interaction-driven oligomers, represented by fluorescence quenching/loss. In these types of peptide structures, the polar amino acids decorate the outside of the oligomers with the Orn⁹/Lys⁹ residues, previously found to be essential for activity, interacting with the electronegative target cell wall. Active peptide moieties, such as amphipathic dimers, are then released from the peptide layers on the material to elicit antifungal activity. After the washing steps, only peptides strongly associated to the material were retained, and if in the correct conformation, could elicit the antifungal response. Organic solvents at higher concentrations resulted in a decreased hydrophobic effect on the peptides, represented by fluorescence dequenching/gain and poor antifungal activity. Here, peptides may either be in the incorrect conformation, stacked too tightly, or deposited as inactive stable oligomers. The potential of the tyrocidines in material functionalisation and the results in this study pave way towards the development of effective antifungal materials. With little to no anticipation of resistance emergence, and by prevention of chronic fungal infections, this study shows the potential of the Trc-functionalised materials for female and baby hygiene products, as well as surface sterilisation. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Die wêreldwye las wat veroorsaak word deur die gebrek aan effektiewe antifungiese middels om toestande soos vulvovaginale kandidiasis (VVC), luierdermatitis en gesondheidsorg-verwante infeksies, veroorsaak deur Candida-spesies, aan te spreek, het 'n dringende behoefte aan innoverende intervensies veroorsaak. Die toenemende weerstand teen huidige antifungiese middels beklemtoon verder die dringendheid van hierdie kwessie. Om hierdie uitdagings aan te spreek, is die verkenning van nuwe oplossings of wysigings aan bestaande toepassings uiters belangrik. In hierdie konteks het antifungiese peptiede (AFP's) as belowende kandidate na vore gekom. Hierdie studie is spesifiek gefokus op die ondersoek van anti-Candida-aktiwiteit, met 'n besondere klem op die tirosidiene (Trcs), 'n natuurlike siklodekapeptied-antibiotikakompleks. Hierdie peptiede word as goeie potensiële kandidate vir verdere ontwikkeling beskou as gevolg van hul breëspektrum aktiwiteit teen bakterieë, swamme, virusse en parasiete, sowel as hul inherente vermoë om aan verskeie materiale te kleef. Onlangse studies het aangedui dat die peptied twee hoof self-samestelling modusse aanneem, afhangende van sy omliggende omgewing, en die kragtige antibakteriese aktiwiteit van die peptied is relatief nie-selektief in terme van tipe materiaal wat gefunksionaliseer is. Hierdie studie het ten doel gehad om die effek van verskillende oplosmiddelsisteme en Trc- peptiedkomplekse op anti-Candida-aktiwiteit van Trc-gefunksionaliseerde materiale te verken, asook die biofisiese opsporing van peptied-selfsassosiasie en materiaalbinding. Die materiale wat ondersoek is, sluit in polistireenplastiek (wat as verwysing gebruik is), sellulose filtreerpapier, viskose en polipropileen velle/doeke. Die Trc-mengsel, Phe-ryke en Trp-ryke peptiedkomplekse is in vier oplosmiddels geformuleer naamlik asetonitriel, metanol (MeOH), etanol (EtOH) en isopropanol (IPA). Optimeringstudies deur die teikenselmetabolisme oor tyd te evalueer het aan die lig gebring dat EtOH goeie materiaaladhesie en effektiewe antifungiese aktiwiteit vir die Trc-mengsel en Phe- ryke kompleks bevorder, terwyl MeOH en IPA soortgelyke effekte op die Phe-ryke en Trp-ryke peptiedkomplekse het. Die robuustheid en stabiliteit van die gefunksionaliseerde materiale is deur 'n reeks wasstappe beoordeel. Hierdie bevindinge het die belangrikheid van aminosuursamestelling in die optimale peptiedneerlegging op die materiale uitgelig. Vanuit die toetsing van 'n industrie- afgeleide metode vir materiaalbehandeling is die gevolgtrekking gemaak dat die gemiddelde polariteit van die peptiedkompleks, oplosmiddelstelsel en die materiaal 'n rol speel. Die Trc-mengsel en Phe-ryke peptiede het makliker met die hidrofobiese polistireen geassosieer, terwyl die meer polêre Trp-ryke peptiedkompleks geredelik geassosieer word met die meer polêre sellulose en viskose. Verder laat die viskose materiaal eweredige verspreiding van die peptied toe, wat lei tot potente antifungiese aktiwiteit. Verder is die verband tussen oppervlak-afgeleide antifungiese aktiwiteit en biofisiese eienskappe van die peptiede in die verskillende etanoliese oplossings tydens neerlegging op materiale beoordeel deur veranderinge in Trp en Tyr fluoressensie waar te neem. Dit het insig verskaf in die impak van peptied-konformasie in oplossing en binding aan 'n spesifieke materiaal, op antifungiese aktiwiteit. Hierdie studie het aangedui dat peptied-oligomere, gedryf deur hidrofobiese interaksies en aromatiese stapeling, lei tot die bou van metastabiele oligomere en is van kardinale belang vir materiaalassosiasie en antifungiese aktiwiteit. In waterige oplosmiddels het water die vorming van hidrofobiese interaksie-gedrewe oligomere aangedryf, verteenwoordig deur fluoressensie- blus/verlies. In hierdie tipe peptiedstrukture versier die polêre aminosure die buitekant van die oligomere met Orn9/Lys9, noodsaaklik vir aktiwiteit, in wisselwerking met die elektronegatiewe teikenselwand. Aktiewe peptieddele, soos amfipatiese dimere, word dan vrygestel van die peptiedlae op die materiaal om antifungiese aktiwiteit te ontlok. Na die wasstappe is slegs peptiede wat sterk aan die materiaal geassosieer is, behou en indien in die korrekte konformasie, het dit antifungiese aktiwiteit gewys. Organiese oplosmiddels by hoër konsentrasies het gelei tot 'n verminderde hidrofobiese effek op die peptiede, verteenwoordig deur fluoressensie- onttblussing/toename en swak antifungiese aktiwiteit. Hier kan peptiede óf in die verkeerde konformasie wees, te styf gestapel wees, óf as onaktiewe stabiele oligomere neergelê word. Die potensiaal van die tirosidiene in materiaal-funksionalisasie en die resultate in hierdie studie baan weg vir die ontwikkeling van effektiewe antifungiese materiale. Met min tot geen verwagting van weerstandigheid, in die voorkoming van kroniese swaminfeksies, toon hierdie studie die potensiaal van die Trc-gefunksionaliseerde materiale vir vroulike en baba higiëne produkte, sowel as oppervlaksterilisasie. | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.format.extent | 175 pages : illustrations (some color) | en_ZA |
| dc.identifier.uri | https://scholar.sun.ac.za/handle/10019.1/130370 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject.lcsh | Antimicrobial polymers | en_ZA |
| dc.subject.lcsh | Candidiasis, Vulvovaginal | en_ZA |
| dc.subject.lcsh | Antifungal agents | en_ZA |
| dc.subject.lcsh | Peptides | en_ZA |
| dc.subject.name | UCTD | en_ZA |
| dc.title | Antifungal activity of antimicrobial polymers created with peptides from the tyrothricin complex | en_ZA |
| dc.type | Thesis | en_ZA |
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