טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBerkov Yifat
SubjectDesign, Synthesis and Evaluation of New Derivatives of
Aminoglycosides for the Treatment of Human Genetic
Diseases
DepartmentDepartment of Chemistry
Supervisor Professor Timor Baasov
Full Thesis textFull thesis text - English Version


Abstract

Genetic disorders occur because of mutations in an individual's DNA. Nonsense mutations are single-point modifications in the DNA, where one of the three stop codons replaces an amino acid-coding codon, leading to a premature termination of the translation process, producing a shortened, nonfunctional protein. These mutations account for approximately 11.5% of the total single gene mutations, and for the majority of the diseases that they cause there is presently no effective treatment.

Aminoglycoside antibiotics are commonly used for the treatment of bacterial infections. They selectively bind to the A-site of the bacterial 16S ribosomal RNA (rRNA), and interfere with translational fidelity during protein synthesis. In the last few years, certain aminoglycosides were suggested as a possible treatment for genetic diseases resulting from nonsense mutations due to their ability to induce eukaryotic ribosomes to readthrough nonsense mutations. Despite their massive therapeutic potential, aminoglycosides frequently cause nephrotoxicity and ototoxicity in treated patients.

In 2006, our lab reported about the initial attempts for the design and synthesis of new derivatives of aminoglycosides with significantly improved activity and low toxicity. This study identified the pseudo-disaccharide paromamine as a minimal structural motive and its pseudo-trisacharide derivative with 5-aminoribose attached to C5 as a most potent readthrough inducer.

             Based on this observation and in attempts to further improve both readthrough potency and toxicity, we designed and synthesized a new series of structures which preserve the already established paromamine scaffold, but instead of a sugar ring, acyclic appendages are attached via carbamate linkage either at position C5 or at position C6. The rationale for the design of acyclic appendages was to increase the interaction of such flexible side chains with the mammalian ribosomal RNA and subsequently to increase the stop codon readthrough activity of the resulted structures.

The structures were synthesized and examined for their ability to suppress nonsense mutations and for the inhibition of protein synthesis. The compounds showed potent readthrough activity, far better than that of the paromamine scaffold.

A few compounds also retained an elevated translation level that could hint about their low toxicity.

This study indicates that the acyclic appendages have a potential for creating better scaffold than paromamine, which after appropriate tuning can lead to potent derivatives that might act as a potential drug.