Design, Synthesis And Biological Activity Of Protein Tyrosine Phosphatase Inhibitors

Protein tyrosine phosphatases (PTPs), in conjunction with protein tyrosine kinases (PTKs), serve as key regulatory components in signal transduction pathways. Defective or inappropriate regulation of PTP activity leads to aberrant tyrosine phosphorylation, which results in many human diseases, such as caners, diabetes and immune dysfunctions. It is very necessary to develop highly efficient PTP inhibitors and probe into their interaction mechanisms between the enzymes and the inhibitors, which contributes to the development of signal transduction in organisms and new drugs against diabetes, cancer and immune dysfunctions. In this dissertation, PTP inhibitors were designed, synthesized and screened, and some results were obtained as follows:A new method has been developed for the synthesis of heterocyclic compounds containing-phosphorus. The mixture of two isomers, phosphachroman-2,4-diones and 4-hydroxyphosphacoumarins, were synthesized. Various phoshpocouamarin derivatives were obtained by acetylation, sulfonylation, phophorylation and alkylation of the isomers, respectively. And a method for construction of new C-C bonds on the cores of phosphacoumarins has been developed through the cross-coupling reactions of 4-tosylphosphacoumarins with organic zincs, arylboronic acids and terminal alkynes, respectively, under palladium and/or copper-catalysts.Several phosphacoumarins with membrane permeability have shown good inhibition activity against SHP-1. These phosphacoumarins have been tested against PTP1B and SHP-1. The results showed that most of the phosphacoumarins had moderate to good inhibition activity against SHP-1, especially, compound 61b exhibited the highest inhibition activity against SHP-1 (K_i = 10μM).3-Benzylidenepentane-2,4-diones have been designed, synthesized and screened against SHP-1 and PTP1B. The bioassay showed that the kind of compounds had good inhibition activity against SHP-1 and PTP1B, and also displayed selectivity for PTP1B. The compounds with good inhibition were docked in the catalytic pockets of SHP-1 and PTP1B on the Sybyl workstation. The docking results are consistent to thebioassay results.A new strategy has been developed for the transition of slow-binding inhibitors to fast ones. Preinhibitors were designed and synthesized by phosphorylation of slow-binding inhibitors, derivatives of (E)-β-nitrostyrene and 7-hydroxycoumarin. The prepared preinhibitors contain parts of both PTP substrates and inhibitors. The preinhibitors could quickly bind with the catalytic site of PTPs, just like the natural substrates, phosphotyrosine. Once binding with catalytic site of PTPs, the preinhibitors were dephosphorylated under the catalysis of the enzyme, which led to the release of the inhibitors in the catalytic pocket. The released inhibitors could bind with the catalytic pocket of PTP and show the inhibition activity against PTPs. The strategy can not only improve the binding rate between inhibitors and enzymes, but also enhance the inhibition activity against enzymes, which brings out a new protocol for the design and modification of enzymatic inhibitors.Electrospray ionization mass spectrometry has been used as a useful tool for the structure determination of phosphacoumarin derivatives. In the dissertation, the positive ESI-MSn spectra of phosphacoumarins derivatives were investigated. The abundant characteristic fragment ions were observed, and the characteristic fragmentation pathways were analyzed, which are useful for the structural determination of other phosphacoumarin derivatives.