Date of Award:
Doctor of Philosophy (PhD)
Chemistry and Biochemistry
Cheng-Wei Tom Chang
This dissertation is composed of two research projects. The first research project is aimed at using synthetic fluorogenic probes to study the possible or dominant linkages in biomass. These probes that mimic the linkages found in lignin-cellulosic biomass are designed to select the optimal fungi from direct evaluation process or could be tested against other microbials to screen candidates which can break ligno-hemicellulose bonds. For the first stage, these probes would be tested against white rot fungi extract. The white rot fungi are used for the first stage to see if releasing or degrading carbohydrates while keeping lignin largely intact is possible or not.
These probes can help to answer fundamental questions, such as what could be the dominant linkages between lignin and hemicellulose, and what are the possible mechanisms for the cleavage of carbohydrates in biomasses. Understanding the linkages in these biomass will enable high efficient degradation or release of carbohydrates, primarily hemicelluloses, from biomass. The second project is focused on synthesizing new aminoglycoside analogs and exploring the potential to revive traditional antibacterial kanamycin as new types of antifungal agents. Aminoglycosides are widely used broad spectrum antibiotics. Although mainly used as antibacterial agents, there have been studies to show amphiphilic aminoglycoside derivatives could be possibly employed as antifungal agents. A concise and novel method for site-selective alkylation of tetra-azidokanamycin has been developed that leads to the divergent synthesis of three classes of kanamycin derivatives. These new amphiphilic kanamycin derivatives bearing alkyl chains length of 4, 6, 7, 8, 9, 10, 12, 14，16 have been synthesized and tested against bacteria and fungi. Surprisingly, the antibacterial effect of the synthesized kanamycin derivatives decline or disappear compared with the original kanamycin A, but some of the compounds show very strong activity as antifungal agents.
Zhang, Qian, "Synthesis of Flouronogenic Probes for Studying Biomass Degradation and Synthesis of New Antifungal Aminoglycosides" (2015). All Graduate Theses and Dissertations. 4472.
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