Food Science and Technology Department
ABILITY OF PHENOLICS IN ISOLATION, COMPONENTS PRESENT IN SUPINA TURF GRASS TO REMEDIATE CANDIDA ALBICANS (A72 and SC5314) ADHESION AND BIOFILM FORMATION
Date of this Version
Alessa,F.(2018).ABILITY OF PHENOLICS IN ISOLATION, COMPONENTS PRESENT IN SUPINA TURF GRASS TO REMEDIATE CANDIDA ALBICANS (A72 and SC5314) ADHESION AND BIOFILM FORMATION. PhD diss. University of Nebraska.
Candida albicans inhabits the gastrointestinal tract dormant commensal member but can become an opportunistic pathogen when the host microflora or immune system is compromised. Adhesion to a biological or synthetic surface, followed by a morphological change from the yeast to hyphae phenotype. Biofilm formation is becoming a common occurrence on types of medical devices. Because C. albicans resistant to commonly available anti-fungal drugs is increasing, innovative treatments are critically needed. Phenolic compounds are promising anti-fungal synergists. Supina grass was used as the complex matrix as it is abundant and highly sustainable source of phytochemicals even though grass cuttings are typically disposed. Therefore, the objective of this research is to determine the potential of phenolic compounds in isolation, as a combination and in present matrix, supina turf grass, to act synergistically in remediating C. albicans adhesion and biofilm formation from a synthetic surface. Chapter 1 of this study focused on the ability of 7 phenols (ferulic, gallic, sinapic, coumaric, epicatechin, catechin and quercetin) and 2 non-phenolic (farnesol and chlorophyll) common in natural systems to combat the cited virulent factors using different incubation times, 1, 3, 6 and 24 h, and treatment dosages (0.06-4.00 mM). The highest potency for occurred at 6 h post treatment but only chlorophyll, farnesol, and catechin were effective against adhesion while all the compounds were able to act against biofilm formation. However, percent remediation ranged from < 0 to 40% with C. albicans (A72) being more stable and G, F being the most effective phenol. Interestingly, the lower dosages resulted in the greatest effectiveness. Chapter 2 describes the ability of two phenols to act synergistically to remediate adhesion and biofilm formation. After screening combination of compounds described above, the same 6 sets were the most effective against adhesion and biofilms, and included F-G, S-Q, F-E, E-C, CAT-Q, and CAT-C. In combination, the non-phenolic compounds in combination were not as effective as in isolation. The efficacy of the phenol combination was 20-60%, which again occurred with the lower dosages, (0.03 0.25) while the higher concentration (up to 4 mM) resulted in limited or no inhibition. The phenols acted synergistically to detach bound cells as the factionary inhibitory concentrations (FIC) was less than 0.05. For the biofilm experiments, with the FIC was 0.51.0 indicating partial synergy. Lastly, Chapter 3 demonstrated that a supina grass extract (at ng levels) was able to remediate C. albicans cellular adhesion and biofilm formation (50-70%). This study therefore generated information on the ability from a readily available agricultural stream, which then is expected to facilitate the development of efficacious anti-fungal treatments capable of remediating potentially life-threatening C. albicans infections.
Advisor: Vicki Schlegel
A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Food Science and Technology, Under the Supervision of Professor Vicki Schlegel. Lincoln, Nebraska: August, 2018
Copyright (c) 2018 Fatima Alessa