Synthetic investigation of small-molecule probes




Bromba, Caleb

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A series of small molecules was synthesized to probe three protein targets in order to elucidate the key small molecule-protein interactions required for potency. Triclosan is an antibacterial compound that has surfaced as a potential environmental hazard and is hypothesized to cause perturbations in the thyroid hormone response of frogs. Using a C-fin assay and a GH3 cell line, our work suggests that triclosan itself may not in fact be the cause of the observed endocrine disruptions. Instead, methyl triclosan (a result of biological methylation during waste water treatment) was shown to disrupt the thyroid hormone response in tadpoles. Secondly, a set of probes was designed based on a cyclopentane scaffold derived from the known neuraminidase inhibitor peramivir. Kinetic assays using both a recombinant neuraminidase protein and an inactivated sample of influenza virus showed that the guanidine group contributes a 10 fold increase in potency while the α-hydroxyl group was observed to have little to no effect. This result suggests that future neuraminidase drug design based on a cyclopentane scaffold may forgo the use of both the guanidinium group and the hydroxyl group to potentially increase the oral availability of these drugs while sacrificing little in the way of potency. Finally, a series of truncated analogues related to the western half of the natural product didemnaketal A was synthesized. These compounds will be used as probes to better understand the mechanism of didemnaketal-mediated protease inhibition. It is hypothesized that a more rigid structure (due to molecular gearing enforced by the presence of additional methyl groups, relative to previously examined analogues) will increase the potency of these molecules toward HIV-1 protease and may lead to new information for designing next-generation dissociative inhibitors. Work was also begun toward the total synthesis of the natural product itself.



Organic Synthesis, Neuraminidase, Triclosan, Didemnaketal, Small-Molecule Probes