Regulation of the Escherichia coli AtoSC two component system by synthetic biologically active 5;7;8-trimethyl-1;4-benzoxazine analogues
摘要:
The Escherichia coli AtoSC two component system; upon acetoacetate induction; regulates the expression of the atoDAEB operon; through His -> Asp phopshotransfer; thus modulating important cellular processes. In this report the effect of seven 5,7,8-trimethyl-1,4-benzoxazine derivatives on the regulation of the E. coli AtoSC system was studied. The new compounds were tested for their effectiveness on the expression of the atoC and the regulated atoDAEB operon. The non-substituted 5,7,8-trimethyl-1,4-benzoxazine (4a), was the most potent inducer on atoC transcription; resulting in accumulation of AtoC protein. The induction of atoC by 4a was specific; since no effect was observed on the other genes of the system (atoS and atoDAEB). Moreover; compound 4a was shown to significantly up-regulate the in vitro kinase activity of the histidine kinase AtoS without altering the protein levels in the cell. Interestingly; this compound appeared to modulate the acetoacetate-mediated induction of the atoDAEB promoter by the AtoSC system. These data provide the first evidence for a differential modulator role of 5,7,8-trimethyl-1,4-benzoxazine; on the AtoSC two component system mediated signaling. (C) 2011 Elsevier Ltd. All rights reserved.
Divergent synthesis of 2,6-diaryl-substituted 5,7,8-trimethyl-1,4-benzoxazines via microwave-promoted palladium-catalyzed Suzuki–Miyaura cross coupling and biological evaluation
作者:Eftychia N. Koini、Nicolaos Avlonitis、Erica S. Martins-Duarte、Wanderley de Souza、Rossiane C. Vommaro、Theodora Calogeropoulou
DOI:10.1016/j.tet.2012.10.009
日期:2012.12
An efficient palladium-catalyzed Suzuki-Miyaura cross-coupling protocol effected in a mixture of DME/water (2:1) enables the reaction of sterically hindered and electron rich 6-chloro or 6-bromo-1,4-benzoxazines(ones) with a variety of aryl, vinyl or alkylboronic acids. Coupling is effected with catalyst loading of 5 mol % using sealed-vessel microwave processing. The resulting compounds exhibit potent activity against Toxoplasma gondii tachyzoite proliferation. (C) 2012 Elsevier Ltd. All rights reserved.