- Structural studies on bioactive compounds. 32. Oxidation of tyrphostin protein tyrosine kinase inhibitors with hypervalent iodine reagents
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Hydroxylated styrenes (tyrphostins) undergo oxidation by hypervalent iodine oxidants such as [(diacetoxy)iodo]benzene (DAIB) to give a range of products depending on the structure of the phenolic substrate, the solvent, the oxidant stoichiometry, and the purification strategy. Conditions have been developed to modify the phenolic component of the tyrphostin without affecting the appended substituted-vinyl moiety. Novel products include: unstable 2-acyloxy-2-methoxy-4-(substituted-vinyl)cyclohexadienones and their rearrangement products 2-acyloxy-4-hydroxy-3-methoxy-1-(substituted- vinyl)benzenes; phenyliodoniophenolates and their rearrangement products iodophenoxytyrphostins; and 3,3'-dialkoxy-2,2'-dihydroxy-5,5'-di(substituted- vinyl)biphenyls. None of these oxidation products displayed enhanced activity in vitro in the NCI 60-cell line panel or in a panel of human breast cancer cell lines, compared to their tyrphostin precursors. The inhibitory activity of three representative tyrphostins (3e,n, 28) was not modulated by aerobic/anaerobic conditions in MCF-7 and MDA 468 cells and was independent of EGFR status in clones of ZR75B cells transfected with this receptor. Basal growth of MCF-7 cells was unaffected by co-administration of the growth factors EGF, TGF-α, IGF-I, and IGF-II, and the new agents did not inhibit EGFR and c-erbB2 autophosphorylation in cell lysates from MDA 468 or SkBr3 cells, respectively, suggesting that receptor tyrosine kinases are not targets for these compounds. Growth stimulation by the tyrphostin 3n in the ER+ breast cell lines MCF-7, T47D, and ZR75-1 was abolished by 1 μM tamoxifen, suggesting that this compound has estrogen agonist activity.
- Wells, Geoffrey,Seaton, Angela,Steven, Malcolm F. G.
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p. 1550 - 1562
(2007/10/03)
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- New solid phase Knoevenagel catalyst
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A new solid phase Knoevenagel catalyst has been prepared and evaluated. The new resin based catalyst reduces by-product formation and has the advantage over conventional Knoevenagel catalysts of simple removal by filtration.
- Simpson, Julie,Rathbone, Daniel L.,Billington, David C.
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p. 7031 - 7033
(2007/10/03)
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- cinnamamide analogs as inhibitors of protein tyrosine kinases
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Protein tyrosine kinases (PTK) arc important signal transducing enzymes involved in the modulation of normal cellular growth and differentiation and have been associated with the etiology of various human cancers. The development of properly designed inhibitors, which block their function by interfering with the substrate binding, may therefore offer an unique target for selective anticancer chemotherapy. Here we describe synthesis and biochemical testing of a novel series of non-peptide PTK inhibitors which have as characteristic active pharmacophore the cinnamamide moiety. For testing we used an exogenous substrate kinase assay based on the phosphorylation of (Val)-angiotensin II with radiolabelled ATP by the catalytic domain of the PTK encoded by the v-abl oncogene (p45 v-abl). The most potent compounds were found in the class of 3-arylidene-2-oxindoles (II) with IC50 values in the 1μM range. Among these the 2-tetralylmethylene-, 4-quinolylmethylene-, 5-quinolylmethylene- and 3-indolylmethylene-2-oxindole compounds of formulae 16, 20, 21 and 24 respectively were selected for further investigation.
- Buzzetti,Brasca,Crugnola,Fustinoni,Longo,Penco,Dalla Zonca,Comoglio
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p. 615 - 636
(2007/10/02)
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- Tyrphostins I: Synthesis and Biological Activity of Protein Tyrosine Kinase Inhibitors
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A novel class of low molecular weight proteine kinase inhibitors is described.These compounds consitute a systematic series of molecules with a progressive increase in affinity toward the substrate site of the EGF receptor kinase domain.These competitive inhibitors also effectively block the EGF-dependent autophosphorylation of the receptor.The potent EGF receptor kinase blockers examined were found to competitively inhibit the homologous insulin receptor kinase at 102-103 higher inhibitor concentrations in spite of the significant homology between these protein tyrosine kinases.These results demonstrate the ability to synthesize selective tyrosine kinase inhibitors.The most potent EGF receptor kinase inhibitors also inhibit the EGF-dependent proliferation of A431/clone 15 cells with little or no effect on EGF independent cell growth.These results demonstrate the potential use of protein tyrosine kinase inhibitors as selective antiproliferative agents for proliferative diseases caused by the hyperactivity of protein tyrosine kinases.We have suggested the name "tyrphostins" for this class of antiproliferative compounds which act as protein tyrosine kinase blockers.
- Gazit, Aviv,Yaish, Pnina,Gilon, Chaim,Levitzki, Alexander
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p. 2344 - 2352
(2007/10/02)
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