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|Section2= |Section3= }} Platensimycin, a metabolite of ''Streptomyces platensis'', which is an excellent example of a unique structural class of natural antibiotics, has been demonstrated to be a breakthrough in recent antibiotic research due to its unique functional pattern and significant antibacterial activity.〔J. Wang, S.M. Soisson, K .Young, S.B. Singh etc,''Nature'' 2006, ''441'', 358-61.〕〔D T. Manallack, I T. Crosby, Y. Khakham and B. Capuano, ''Current Medicinal Chemistry'' 2008, ''15'', 705-710.〕 This compound is a member of a class of antibiotics which act by blocking enzymes involved in the condensation steps in fatty acid biosynthesis,〔D. Häbich, F. Von Nussbaum, ''ChemMedChem'' 2006, ''1'', 951-954.〕 which Gram-positive bacteria need to biosynthesise cell membranes (β-ketoacyl-(acyl-carrier-protein (ACP)) synthase I/II (FabF/B)). Other enzymes in this pathway have similarly been proven antibiotic targets for example FabI, the enoyl-ACP (acyl carrier protein) reductase, that is inhibited by isoniazid and related compounds and the antiseptic agent triclosan.〔H T. Wright, and K.A Reynolds, ''Curr Opin Microbiol '' 2007, ''10'', 447-53.〕 ==History== Platensimycin was first isolated from a strain of ''Streptomyces platensis'' by the Merck group () by using two-plate system where control organisms were compared to cells expressing fabF antisense RNA. This method uses the combination of target-based whole-cell and biochemical assays. The advantage of this method is that the concentrations of compounds in these extracts is sometimes too low to be identified in whole cell assays but are easily found in this two-plate assay system. They tried to find a drug targeting condensing enzymes and can be used clinically. Therefore, they systematically screened 250,000 natural product extracts (83,000 strains in three growth conditions) led to the identification of a potent and selective small molecule from a strain of Streptomyces platensis recovered from a soil sample collected in South Africa. This molecule, platensimycin (C24H27NO7, relative molecular mass 441.47), comprises two distinct structural elements connected by an amide bond. They still showed that Platensimycin has potent, broad-spectrum Gram-positive activity ''in vitro'' (Table below) and exhibits no cross-resistance to other key antibiotic-resistant bacteria including Methicillin-resistant Staphylococcus aureus(MRSA), vancomycin-intermediate S. aureus, vancomycin-resistant Enterococci, and linezolid-resistant and macrolide-resistant pathogens. () A first total synthesis of racemic platensimycin has been published.() Its structure consists of a 3-amino-2,4-dihydroxybenzoic acid polar part linked through an amide bond to a lipophilic pentacyclic ketolide.〔K. C. Nicolaou, A. Li, D. J. Edmonds, ''Angew. Chem.'' 2006, ''118'', 7244-48.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Platensimycin」の詳細全文を読む スポンサード リンク
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