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Date of Award

2013

Document Type

Dissertation - Pacific Access Restricted

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Pharmaceutical and Chemical Sciences

First Advisor

Liang Xue

First Committee Member

Andreas Franz

Second Committee Member

Jianhua Ren

Third Committee Member

Wade Russu

Fourth Committee Member

Vyachslav Samoshin

Abstract

It has long been known that the efficiency of anticancer drugs is limited by the emergence of resistance due to the evolving repair of such DNA lesions in malignant cells. Therefore, development of pharmaceutical agents, which can interfere with the DNA repair pathways, may represent a novel approach to enhance the cytotoxic effects of chemotherapy by reducing drug resistance. Abasic sites (AP sites) are the key intermediates in the BER pathway and promising targets for BER inhibition. In chapter 2, we report the synthesis of two small molecules specifically targeting at AP sites and the evaluation of their activity in terms of interstrand crosslinking formation. Our results show no covalent adduct is induced, which is due to the weak DNA binding affinity. In chapter 3, we try to use TFOs to deliver the interstrand crosslinking moiety to the AP site in a sequence specific manner. Two modified phosphoramidites were synthesized and incorporated into the 5' end of TFOs. The activity was evaluated by using various biophysical and biochemical experiments. The work reported in chapter 4 is focused on the G-quadruplex structure formed in the guanine rich telomeric sequence. Many studies have shown G4 ligands can induce and stabilize G-quadruplex within telomere region and inhibit the activity of telomerase that is overexpressed in 80-90% of cancer cells. Our results indicate that phenanthroline based metal complexes, Ni(Phen) 2 , have strong binding affinity and selectivity towards G-quadruplex over duplex DNA. The effect of Ni(Phen) 2 on telomerase activity and cytotoxicity towards cancer cells was also investigated. Calixarenes containing DNA building units such as nucleotides, nucleosides, and nucleobases have recently aroused much interest because of their versatile applications. In chapter 5, we report the synthesis of calix[4]arenes ( 5.11-5.14 ) functionalized with a single nucleobase (thymine, adenine, guanine, or cytosine) at the upper rim via click chemistry. Their complexation with alkali metal ions was examined using MALDI-TOF mass spectrometry and their molecular interactions were determined using 1 H NMR. All calix[4]arene derivatives show good complexation with alkali metal ions with apparent selectivity. The results also reveal that nucleobase-calix[4]arenes are capable of self-association in CDC1 3 and calix[4]arenes bearing complementary nucleobases can bind to each other via base pairing.

Pages

347

ISBN

9781303533952

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