Investigation of bioactive natural compounds for cardiovascular diseases and daqu fermentation, and the exploration of Beauveria bassiana as a biocontrol agent for the mountain pine beetle epidemic
Creators: Fernandez, Kleinberg Xiandrell
Publisher: name: University of Alberta Library
Year: 2024

<p>Peptide-based compounds are crucial components of current research and development efforts, namely in the field of pharmaceutical therapeutics. Peptides possess complex secondary structures, resulting in a wide array of functions (e.g., signalling, or cellular structural capabilities). Advances in the introduction of non-canonical amino acid building blocks have allowed for the synthesis of diverse analogues of naturally-derived peptides through solid phase peptide synthesis (SPPS). In this thesis, several modifications (e.g., N-methylation, homologue-substitution, etc.) were used to develop non-canonical amino acids to form highly-stable and biologically active apelin analogues.</p>

<p>Apelin is a 77-amino acid long prepropeptide, which is cleaved into the resulting active isoforms: apelin-55, apelin-36, apelin-17, and (pyr-1)-apelin-13. Apelin peptides are part of the cardioprotective hormone system (i.e., apelinergic system), alongside the G-protein coupled apelin (APJ) receptor. The apelinergic system is an influential regulator of various metabolic functions, including nitric oxide production and cardiovascular output. In addition, apelin peptides have also shown promise as biomarkers for cancer diseases and as regulatory components for age-associated sarcopenia. In this study, we probed the extension of apelin peptides at the N-terminus through the addition of head group-protected PEG chains, to determine the optimal modifications for stability against KLKB1 proteolysis. In addition, homologue substitution at the critical RPRL binding site was performed to further analyze the peptide-receptor interactions at this vital site. Furthermore, alanine scans and methylation efforts were performed on the four N-terminal residues for apelin-17 peptides to determine the importance of these amino acid substitutions and conformational restrictions on receptor binding and activation. In addition, ongoing work on retro-enantio peptides is being undertaken to determine the significance of the apelin peptide backbone. Lastly, work is being performed to explore the potential of apelin peptides as oral-based therapeutics through the synthesis of polysaccharide-based hydrogels. Through synthetic interventions, we can optimize naturally-derived and cardio-physiologically-essential apelin peptides to surmount their metabolic liability and clearance and harness such analogues as potent therapeutic drug targets for cardiovascular health.</p>

<p>Work on the determination of the effects of microbial composition on daqu fermentation will also be explored. Daqu is a saccharification starter in the fermentation process for the production of baijiu, an extremely popular Chinese liquor. In this study, a comprehensive qualitative analysis of the production of several lipopeptide congeners, produced by Bacillus spp. was performed on several fermentation conditions (i.e., LB broth, and simple and complex daqu). It is important to determine the contribution of these diverse lipopeptides on the resulting bacterial community assembly, to assess the quality of the baijiu end product.</p>

<p>In a tangential direction, work was directed towards the investigation of Beauveria bassiana as a biocontrol agent for the management of the mountain pine beetle (MPB), or Dendroctonus ponderosae, population. First, this fungal strain was tested in vitro and in planta conditions to determine their conidial stability and efficacy. A fermentation approach was also developed to produce multi-hundred-gram scale of conidial biomass. Furthermore, in natura field infection experiments were performed to determine the effects of B. bassiana on the MPB reproductive success. Lastly, analyses of the genomic and transcriptomic features of B. bassiana were performed to identify sources of virulence and secondary metabolite biosynthesis. Through cultivation and formulation, these fungal strains can withstand the conditions inhabited by the mountain pine beetle, to exert their biocontrol potential on these forest pests.</p>