Liquid chromatographic investigation of quinoxaline antibiotics and their analogues by means of ultraviolet diode-array detection.
Numerical formats for evaluation of spectral purity and for spectral comparison of ultraviolet diode-array detector data, together with library search routines, were applied to the liquid chromatographic analysis of echinomycin, triostin A and their synthetic and biosynthetic analogues. Samples of monoquinoline and bisquinoline analogues of echinomycin were found to contain echinomycin and the other respective analogue. Triostin A and its undermethylated synthetic analogues, des-N-tetramethyltriostin A (TANDEM) and [MeCys3,MeCys7]-TANDEM, were each composed of two or more components. Triostin A primarily consisted of a major chromatographic component and a minor component with very similar ultraviolet spectral features. TANDEM exhibited three chromatographic components with nearly identical ultraviolet spectral characteristics. Apparent conformational interconversion of at least two forms of the [MeCys3,MeCys7]-TANDEM analogue was observed by reversed-phase liquid chromatography. An activation energy of 15 kcal/mol was estimated for the interconversion based upon an Arrhenius plot of the data.
Alfredson
T V
TV
Department of Chemistry, University of California, Davis 95616.
Maki
A H
AH
Adaskaveg
M E
ME
Excoffier
J L
JL
Waring
M J
MJ
D000900:Anti-Bacterial Agents / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004448:Echinomycin / Q000032:analysis; D011810:Quinoxalines / Q000032:analysis*; D014466:Ultraviolet Rays
D000900:Anti-Bacterial Agents; D011810:Quinoxalines; C031945:triostin A; D004448:Echinomycin; C017738:TANDEM (quinoxaline)