title: Structural elucidation of biologically active neomycin N-octyl derivatives in a regioisomeric mixture by means of liquid chromatography/ion trap time-of-flight mass spectrometry.
abstract: Structural elucidation of six regioisomers of mono-N-octyl derivatized neomycin is achieved using MS(n) (up to n = 4) on an ion trap time-of-flight (IT-TOF) instrument equipped with electrospray ionization. The mixture of six derivatized neomycin analogues was generated by reductive amination in a shotgun synthetic approach. In parallel to the liquid chromatography/mass spectrometry (LC/MS) detection, the antibacterial activity of the neomycin regioisomers was tested by post-column addition of buffer and bacterial inocula, subsequent microfractionation of the resulting mixture, incubation, and finally a chemiluminescence-based bioactivity measurement based on the production of bacterial ATP. The MS-based high-resolution screening approach described can be applied in medicinal chemistry to help in designing and producing new antibiotic substances, which is particularly challenging due to the high functionality of most antibiotic substances, therefore requiring advanced (hyphenated) separation and detection techniques for compound mixtures.
authors.affiliation: BioMolecular Analysis Group, Department of Chemistry, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands. mgiera@few.vu.nl
authors.forename: Martin
authors.initials: M
authors.lastname: Giera
authors.forename: Jon S B
authors.initials: JS
authors.lastname: de Vlieger
authors.forename: Henk
authors.initials: H
authors.lastname: Lingeman
authors.forename: Hubertus
authors.initials: H
authors.lastname: Irth
authors.forename: Wilfried M A
authors.initials: WM
authors.lastname: Niessen
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001681:Biological Assay / Q000379:methods*; D002853:Chromatography, Liquid / Q000379:methods*; D004926:Escherichia coli / Q000187:drug effects; D013058:Mass Spectrometry / Q000379:methods*; D008826:Microbial Sensitivity Tests / Q000379:methods; D009355:Neomycin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D000255:Adenosine Triphosphate; D009355:Neomycin