Design, Synthesis And Biological Evaluation Of Nitroimidazole//N-oxide Containing EGFR Inhibitors Exerting Hypoxia Activated Cytotoxicities

Hypoxia is a common characteristic of solid tumors resulting from the insufficient blood supply which fails to meet the rapid tumor growth. On the other hand, this specific microenvironment of tumors distinguished it from physiologically normal cells and made it as an attractive and exploitable therapeutic target. Nowadays, many small molecules have been explored to specially target tumor hypoxia.Meanwhile, the expression of epidermal growth factor receptor (EGFR) is up-regulated under tumor hypoxia. As a member of HER family, EGFR plays a vital role in cellular signaling transduction processes. The over-expression of EGFR has been observed in many solid tumors, including colon, ovarian, non-small cell lung cancer (NSCLC) and so on, which plays an intimate role in the poor prognosis of patients. EGFR inhibition has been developed as one of the most efficient strategies for cancer therapy. Based on the above reports, we envision that EGFR inhibitors containing hypoxia activated pharmacophore may exert efficient antitumor activities both under normoxia and hypoxia.Four series of EGFR inhibitors were designed and synthesized through incorporating of the hypoxia activated 2-nitroimidazole moiety into the EGFR inhibitor scaffold. Firstly,45 compounds were synthesized by introducing the nitroimidazole group into the C-6 and C-7 position of the 4-anilinoquinazolines. Among them,35 compounds exhibited the IC50 values lower than 5 nM, and 8 compounds displayed more potent anti-proliferative activities than gefitinib against A549 and HT-29 cells both under normoxia and hypoxia. Compound 1-50 and 2-28 were considered to better than the others and were chosen for further evaluation. The mimic reduction activity test revealed the proposed reductive activation process of 1-50 and 2-28. The metabolic stabilities assay indicated that compound these compounds were relatively stable under normoxia and could be easily metabolic activation under hypoxia. The docking study predicted the binding modes of these compounds with EGFR kinase.21 compounds were also got by incorporating the 2-nitroimidazole moiety into the C-4 aniline position of the 4-anilinoquinazolines and 10 of them exhibited more potent anti-proliferative activities than lapatinib. The most promising compound 3-43 was taken to dock with EGFR and their proposed binding mode was exhibited.The 2-nitroimidazole containing 4-anilino-pyrrolo[3,2-d] pyrimidine derivatives were explored as EGFR inhibitors as well and 11 new compounds were synthesized. The primary SAR studies revealed that the introduction of the 2-nitroimidazole moieties into the N-5 position of the pyrrolo[3,2-d]pyrimidine scaffold was optimal for activity.We also explored the nitrogen oxide containing small molecules as hypoxia activated EGFR inhibitors. Among the exploration process, a new synthetic way to the pteridinones was found. When introducing the alkyl tertiary amine N-Oxides to the 4-anilinoquinazolines, the newly obtained compounds lost their anti-proliferative activities. Introducing the oxide to the N-1 position of the 4-anilinoquinazolines made the moles unstability. The 3-cyano-4-anilinoquinoline-1-oxides showed excellent enzymatic inhibitory and anti-proliferative activities, and they got the reductive activated properties under hypoxia as well, which accords to our expectation.