Title

Evaluation of human liver metabolism of compounds that reactivate mutant p53 in human cancer cells.

Date of Award

5-1-2016

Document Type

Thesis

School

College of Liberal Arts

Degree Name

Bachelor in Arts

Abstract

A recent approach for a cancer therapy is the reactivation of the mutant p53, tumor suppressor protein that is mutated in about 50% of all human cancers. The Doll Lab has identified compounds of the benzimidazole class that reactivate mutant p53 in human cancer cells. Drug discovery is concerned with the optimization of lead structures that show biological activity towards targeted diseases. This involves optimization of compounds that have improved potency, selectivity and drug-like properties. Two critical drug-like properties are the ability of a compound to cross biological membranes and to possess human metabolic stability. Metabolic stability is important for patient compliance and lower dose/toxicity of compounds. Thus, as part of the optimization of such lead structures, the metabolic profile has to be evaluated - which in this context includes metabolic rate and the identity of metabolites. This research focuses on improving metabolic profiles of candidate drugs by establishing a structural activity relationship for the in vitro human metabolism. We determined the benzimidazole class of compounds undergo hydroxylation by CYP450 in the Phase I metabolism by human liver microsomes. In order to improve metabolic stability, structural changes were made to the lead benzimidazole compounds. We report here that addition of electron with drawing groups - like fluorine - to the benzimidazole ring portion of the lead structures slowed down the metabolic rate. Furthermore, addition of electron-donating groups - such as methyl - to the benzimidazole ring portion accelerated the metabolic rate by CYP450. All synthesized and studied compounds undergo at least single hydroxylation by CYP450 at the benzimidazole ring portion. Amide benzimizaole analogues were found to be less metabolically stable than urea benzimidazole analogues prior to fluorination. Once fluorinated, amide and urea benzimidazoles were closer in metabolic rates - which indicates that the effect of fluorination on amide benzimidazoles is larger than in urea benzimidazoles. We find the fluorinated benzimidazole analogues have metabolic rates that are similar to metabolic rates of some marketed drugs. This indicates the benzimidazole class of compounds is a reasonable structural class for drug discovery. Newly synthetized compounds still have to be evaluated for membrane transport rate for the GI and BBB membranes, as well as the reactivation of mutant p53 and toxicity in human cancer cells.