RESUMO
Regioselective oxidation of methyl beta-muricholate to give the 6-ketoderivative is described. Stereoselective reduction of this ketone with tritiated NaBH4 furnishes labeled methyl beta-muricholate. The structure of all compounds was confirmed by infrared, 1H, and 13C nuclear magnetic resonance spectroscopy. Data obtained by circular dichroism and mass spectroscopy were in agreement with the structure of the ketone 3.
Assuntos
Ácidos Cólicos/síntese química , Ácidos Cólicos/química , Cromatografia em Camada Fina , Dicroísmo Circular , Marcação por Isótopo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Oxirredução , Trítio/químicaRESUMO
Dekamycin was isolated from strain DK5 of Streptomyces fradiae, and purified by ion-exchange column chromatography. Excellent separation of N-acetylated derivatives of the antibiotic mixture was achieved by two different methods, flash chromatography and high-performance liquid chromatography. Mass spectrometry (252Cf plasma desorption mass spectrometry, fast atom bombardment) for the analysis of N-acetyldekamycins (neomycin B, neomycin C, neamine and ribostamycin) was mainly used to confirm the molecular weight of a structure deduced by 1H and 13C NMR analyses.
Assuntos
Aminoglicosídeos , Antibacterianos/análise , Acetilação , Antibacterianos/biossíntese , Cromatografia Líquida de Alta Pressão , Cromatografia por Troca Iônica , Cromatografia em Camada Fina , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Peso Molecular , Streptomyces/metabolismoRESUMO
The first chemical synthesis of 3 alpha, 7 alpha-dihydroxy-5 beta-androstan-17-one and 3 alpha-hydroxy-5 beta-androstane-7, 17-dione is reported. In this method, the 17 beta-side chain of commercial chenodesoxycholic acid was degraded in 6 steps after selective protection of the hydroxyl groups: 3 alpha-OH by a tert-butyldimethylsilyl group and 7 alpha-OH by an acetoxy group. The capacity of 3 alpha, 7 alpha-dihydroxy-5 beta-androstan-17-one and 3 alpha-hydroxy-5 beta-androstane-7, 17-dione to release a pyrogen by human leukocytes was investigated by two independent methods: supernatants from leukocytes incubated with a steroid are injected to rabbits whose fever is measured, or tested by the Limulus Test (a pyrogen detection technique). The 7-keto substituted etiocholanolone still possessed pyrogenic activity, while the 7 alpha-hydroxyl substituted one did not.
