|M.Sc Student||Shtenberg Yarden|
|Subject||Synthesis and Evaluation of New Derivatives of|
Aminoglycosides for Treatment of Genetic Diseases
|Department||Department of Chemistry||Supervisor||Professor Timor Baasov|
|Full Thesis text|
Aminoglycosides (AGs) are broad spectrum antibacterial agents that were proved to interact with the A-site of the prokaryotic ribosome and interfere with the proofreading process. Studies have shown the ability of certain AGs to participate in the eukaryotic translation process, which enables the ribosome to readthrough the nonsense codon, resulting in full-length functional proteins. However, the use of AGs for systematic treatment of genetic diseases suffers from serious disadvantages, e.g., nephrotoxicity and ototoxicity in treated patients, multi-variables affecting the readthrough process, and lack of selectivity to the eukaryotic ribosome. Thus, the objective of this research is to design, synthesize and evaluate the activity of new AG-based molecules with improved permeability and binding affinity, possessing sufficient readthrough activity, low toxicity and high selectivity to the eukaryotic ribosome.
Initial attempts to increase cell membrane permeability of the target scaffold included selective substitution of a guanidinium moiety on N-1 position (NB150) or 5’’ position (NB151, NB152) of our known lead compounds NB82, NB74 and NB84, respectively. The synthesis originated from the commercial G418 as a starting material, which is the strongest readthrough inducer tested to date. The target structures NB150, NB151 and NB152 were synthesized by multiple steps and the final homogeneously pure materials were biologically evaluated. Both, in-vitro and ex-vivo suppression tests of NB150, NB151 and NB152 have shown significantly reduced readthrough activity in comparison to our lead compounds.
On the next step, we attempted to redesign the pseudo-disaccharide scaffolds of paromamine and NB82 into more advanced scaffolds by using rational design. Based on recently reported x-ray structures of AGs bound to various ribosomal particles and whole eukaryotic ribosome, and subsequent modelling study we designed and synthesized two new scaffolds containing 6’,7’-diol (NB153) and unsaturated ring I (NB154), which were then biologically evaluated. Preliminary in-vitro suppression tests demonstrated high readthrough activity of NB153 compared to that of NB82, and significantly higher than paromamine. NB154 that exhibits unsaturated ring I showed significantly higher readthrough activity than that of its parent paromamine and a similar activity to NB82.
In conclusion, by discovering the benefits gained with these two new scaffolds, we have opened a new direction for the construction of AG-based new readthrough inducers that may act as potential drug for the treatment of human genetic diseases.