Design, Synthesis And Biological Evaluation Of Anti-cancer Agents Targeting PI3K

Cancer is becoming the second disease threat to human health worldwide. Traditional anti-cancer agents, which directly interfere with mitosis, DNA synthesis, and repair systems, are often connected with drawbacks such as low efficacy and high toxicity. A number of key signaling pathways, membrane receptors, kinases and other biological macromolecules, which play an important role in tumorigenesis and cancer development, have been identified along with the further understanding of the pathogenesis of human cancer. Development of small molecular drugs specially targeting these specific macromolecules provides opportunities to overcome human cancers. Small-molecule inhibitors targeting key knots of cellular signaling pathways are new class of anti-cancer agents. Phosphoinositide 3-kianses (PI3Ks) are family of lipid kinases that regulate crucial cellular events such as proliferation, survival, growth, metastasis and apoptosis. Extensive studies have established the close connection between tumor genesis and PI3K, and a growing number of studies showed that PI3K is a promising target for cancer treatment. Consequently, development of novel small molecule PI3K inhibitors has become the hot spot in drug research for anti-cancer treatment.In this thesis, we focused on the design, synthesis and biology evaluation of novel small molecule as new potent PI3Ka inhibitors.113 compounds (112 of them were firstly reported) were designed and synthesized by the principle of rational drug design and virtual screening program. All of these compounds were charactered by 1H-NMR, MS-ESI and elemental analysis, some of them (1-4a-1-4y) were charactered by C-NMR. Additionally, the structures of 5 compounds (1-4p,3-4a, 5-7o,5-7r,5-7s) were further confirmed by X-ray diffraction. The research were summarized as followed.Based on the structures of the Wortmannin and LY294002, and their binding models with PI3Kα, chromone plays an important role in inhibitory activity. In addition, a five membered nitrogen containing heterocycle was found in BEZ235 and GDC0941, and it also takes an important role in inhibitory activity. Based on the principle of rational drug design, chromeno[4,3-c]pyrazol-4(2H)-one was defined as the so-called core region. Furthermore, benzyl and chain alkyl are introduced into the N atom and expected to gain binding affinity and selectivity. On the basis of the ideas we assumed, twenty-five chromeno[4,3-c]pyrazol-4(2H)-one derivatives were designed and synthesized. Most compounds showed the good proliferative activity, which were superior to LY294002, and the compounds containing the benzyl structure exhibited better antiproliferative activities than that of alkyl group. It was observed that compounds 1-41 and 1-4m showed the most potent antiproliferative activity (IC50= 0.08,0.19μM for HCT116, respectively). What’s more, compounds 1-41 (IC50=0.014 μM) and 1-4m (ICso=0.046 μM) showed a certain selectivity over PI3Ka. Docking simulations showed that the binding modes of compound 1-41 at the active site of PI3Ka is the similar to that of wortmannin which reported as reference (Fig.l). It indicated that the potential of developing the chromeno[4,3-c]pyrazol-4(2H)-one derivatives as a means of cancer treatment by targeting PI3Ka.Based on the result aboved, followed by structure-based drug design principles and molecular docking, a novel chromeno[4,3-c]pyrazol-4(2H)-one derivatives were designed and synthesized which contained piperazine and sulfonyl fragments. Out of the sixty-nine compounds, most compounds showed the good proliferative activity, which were also superior to LY294002, and some compounds displayed the potent inhibitory activities against PI3Kα such as compounds 2-4o (IC50:0.021 μM),3-4p (IC50:0.012μM),4-7m (IC50:0.009μM) and so on. The structure-activity relationship (SAR) indicated that the larger of the the substituent’s steric hindrance in compound, the better of the inhibitory activity, and the stronger of the substituent’s hydrophobic, the better of the inhibitory activity. And the compounds containing the benzyl structure exhibited better inhibitory activities than that of alkyl group. The result showed that these compounds could be potential PI3Kα inhibitors.In addition, in order to enhance the steric hindrance of substituent, the N-heterocyclic fragment phenylpiperazine, benzhydrylpiperazine, morpholine and piperidine were introduced into the chromeno[4,3-c]pyrazol-4(2H)-one by acetyl, and nineteen compound were designed and synthesized. It was found that the compound 5-7p and 5-7q which contained benzhydrylpiperazine fragment showed good proliferative activity, it also exhibited the potent inhibitory activity against PI3Ka (5-7p, IC50=0.074 μM; 5-7q, IC50=0.016 μM). All aboved, these results provided a reliable idea for chromeno[4,3-c]pyrazol-4(2H)-one derivatives as PI3Ka inhibitors.