Structure Based Design Synthesis and Biological Evaluation of Substituted Porphyrin Analogues as Potent G Quadruplex Binding Telomerase Inhibitors

Abstract

newline Antitumor agent targeting DNA and DNA-associated processes are widely used in the newlinetreatment of human cancers and provoke significant increases in the survival of patients. One of newlinethe most unique factors distinguishing cancer cells from normal cells is the high telomerase newlineactivity and high proliferation potency. The very basic idea of this thesis is based on this fact and newlineG-quadruplex inhibition is choosed as the target. Due to highly aromatic character and unique newlinestructural features of porphryin made it responsible for taking candidate for drug design. In this newlineresearch work structure based drug design was carried out using porphryin analogues on crystal newlinestructures of a parallel stranded human telomeric quadruplex in complex with the porphyrin newlineTMPyP4 PDB ID: 2A5R and tetra-(4-n-methylpyridyl) porphin with monomeric parallelstranded newlineDNA tetraplex of c-myc promoter PDB ID: 2HRI. The active binding site was studied newlineon these sequences. The selected ligands are posed against these oligoniceotide sequences. The newlineconformation flexibility of ligands was considered by exhaustive conformational search within newlineglide augmented by heuristic screen that removed conformations which were not suitable for newlinebinding. Using grid box docking was carried out and the resulting dock conformations were newlineanalyzed for binding score. The high scoring PYP series of compounds were selected for newlinesynthesis. After characterization in vitro biological evaluation was carried out using PCR stop newlineand MTT assay procedure. DNA polymerase primer extension reactions were carried out on four newlinerepeats of the human telomeric sequence, G-quadruplex forming (QF), Temp [TTAGGG]4. The newlineinhibition intensity of full length product is then monitored with respect to concentration of newlinecompound. The resulting values are compared against four repeats of a non-G-quadruplexforming newlinesequence (NQF), Temp[TTAGAG]4 to demonstrate the selectivity of PYP compounds newlinetowards the G-quadruplex DNA. The selected compounds evaluated for in vitro cell growth newlineinhibition, expresse