Synthesis And Biological Activity Of Novel Phthalazinones As Aurora B Kinase Inhibitors

The phthalazinone,as an effective pharmacophore,is widely used in drugs including antitumor,analgesic,anti-inflammatory,antibacterial and antiviral,such as Olaparib,Talazoparib and Azelastine.Aurora kinases are a member of the serine/threonine kinase family that play an important role in the regulation of mitosis.The overexpression of Aurora kinases has been found in a variety of tumors and is positively correlated with poor prognosis.As one of the popular targets for antitumor,a large number of Aurora kinase inhibitors have been discovered and entered into clinical research including SNS-314,AMG900,VX680,AZD1152 and AT-9283.In this thesis,we designed and synthesized some 2,4-disubstituted and 4-substituted phthalazinones targeting Aurora kinases and evaluated their biological activities.Firstly,intermediate 7b was synthesized by substitution of 4-bromophthalazin-1（2H）-one with 4-fluoronitrobenzene or p-nitrobenzyl chloride.Following,2,4-disubstituted phthalazinones were prepared through Suzuki coupling reaction or palladium-catalyzed carbon-nitrogen cross coupling reaction,iron powder reduction reaction,and the reaction of amino groups with isocyanates.Simultaneously,1,4-dibromophthalazine was used to synthesize compounds 17a?b in ethanol.Then the laters were refluxed in glacial acetic acid to form a ketone,and reduction with iron powder or removing Boc group,finally reacting with isocyanate provided4-substituted phthalazinones.We evaluated the anti-proliferative activity of the target compounds against A549,HCT116,MCF-7 and HepG2 tumor cellss by MTT assay.We found that compounds 22h and 25a could effectively inhibit the proliferation of four tumor cells with IC₅₀ values ranging from 0.30μM to 4.88μM and 4.36μM to11.97μM,respectively.Kinase inhibition assay showed that compound 25a possessed strong selective inhibitory activity against Aurora B kinase with the IC₅₀ value of 142nM.Western Blot suggested that the expression of p-Aurora B was significantly decreased in a dose-dependent manner in HCT116 cell treated with compound 25a.Meanwhile,compound 25a arrested cell cycle at G2/M phase by down-regulating the expression of CyclinB1 and Cdc2,and induced the cell apoptosis by up-regulating the expression of BAD and Bax in HCT116 cells.Molecular docking revealed that compound 25a could form key hydrogen bonds with Ala173,Glu171 and GlU177 in Aurora B kinase.In summary,two series of novel phthalazinones were synthesized and evaluated for their antitumor activity in this thesis.We found that 2,4-disubstituted phthalazinones showed potent antiproliferative activity against tumor cell lines although their mechanism need to further clarify.And 4-substituted phthalazinones were strong Aurora B kinase inhibitors as antitumor drugs.All the findings provided a solid foundation for finding novel phthalazinones as Aurora kinase inhibitors.