title: Fluorescein-labeled Bacitracin and Daptomycin Conjugates: Synthesis, Fluorescence Imaging and Evaluation.
abstract: BACKGROUND
  Previously, glycopeptides antibiotics such as vancomycin, ramoplanin and an antifungal antibiotic nystatin have been studied for their diagnostic and therapeutic potential.
  
  
  OBJECTIVE
  To further explore the diagnostic and chemotherapeutic potential of other antibiotics we have now employed daptomycin, a lipopetide antibiotic and bacitracin, a polypeptide antibiotic in uptake and vitality tests on human cell lines.
  
  
  METHODS
  Fluorescent conjugates of bacitracin and daptomycin were synthesized using fluorescein isothiocynate (FITC) for confocal laser scanning microscopy (CLSM) and fluorescence activated cell sorting (FACS). The cellular uptake of the synthesized daptomycin and bacitracin conjugates was studied on seven human cell lines, two healthy and five malignant using CLSM and FACS. To examine the cell membrane damage caused by the conjugates FACS experiments were carried out using propidium iodide.
  
  
  RESULTS
  The uptake pattern was different for both antibiotics for all the cell lines. The cytoplasmic uptake of daptomycin conjugate was lower than the bacitracin conjugate, resulting in decreased cell membrane damage.
  
  
  CONCLUSIONS
  No preferential uptake into malignant or healthy cells was found for the two different antibiotic conjugates and the uptake patterns were also different between the two antibiotics. However, the lower cytotoxicity and different uptake mechanism makes daptomycin conjugate a prospective candidate for further study as a diagnostic agent for various intracellular infections.
authors.affiliation: Department of Neuroradiology, University of Tübingen, Hoppe-Seyler-Str.3, 72076 Tübingen; Germany.. Germany.
authors.forename: Sumbla
authors.initials: S
authors.lastname: Sheikh
authors.forename: Alexander
authors.initials: A
authors.lastname: Sturzu
authors.forename: Hubert
authors.initials: H
authors.lastname: Kalbacher
authors.forename: Thomas
authors.initials: T
authors.lastname: Nagele
authors.forename: Christopher
authors.initials: C
authors.lastname: Weidenmaier
authors.forename: Marius
authors.initials: M
authors.lastname: Horger
authors.forename: Christian
authors.initials: C
authors.lastname: Schwentner
authors.forename: Ulrike
authors.initials: U
authors.lastname: Ernemann
authors.forename: Stefan
authors.initials: S
authors.lastname: Heckl
mesh_terms: D001414:Bacitracin / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D002469:Cell Separation; D017576:Daptomycin / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D019793:Fluorescein / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D057809:HEK293 Cells; D006801:Humans; D061986:MCF-7 Cells; D018613:Microscopy, Confocal; D015394:Molecular Structure; D061848:Optical Imaging; D014407:Tumor Cells, Cultured
chemical_list: D005456:Fluorescent Dyes; D001414:Bacitracin; D017576:Daptomycin; D019793:Fluorescein
keywords: Daptomycin; bacitracin; cytotoxicity.; fluorescence imaging; fluorescent conjugates