title: Ramoplanin imaging conjugates--synthesis and evaluation.
abstract: In a previous study we found that fluorescence-marked vancomycin--a glycopeptide antibiotic--is taken up into human tumor cells. To expand on these investigations we now used the lipoglycodepsipeptide antibiotic ramoplanin. Compared to vancomycin it is not only a bigger molecule, but it also has two potential binding sites for coupling to the imaging agents. Three different ramoplanin imaging conjugates were synthesized, two used for fluorescence imaging and one for magnetic resonance imaging. The two fluorescent dyes used in confocal laser scanning microscopy (CLSM) and fluorescence activated cell sorting (FACS) were fluorescein isothiocyanate (FITC) and rhodamine isothiocyanate (RITC). The third was the magnetic resonance imaging (MRI) contrast agent gadolinium-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (GdDOTA). The uptake of ramoplanin conjugates, their specificity for different cell lines and the accessibility of the conjugates by imaging methods were evaluated on 8 human cell lines (two benign, six malignant) by CLSM, FACS and MRI experiments. Cytotoxicity of the ramoplanin conjugates was determined in the FACS experiments with the propidium iodide and Annexin-V-Fluos indicating any disruption in the cell membranes. Cytoplasmic uptake of the ramoplanin conjugates was observed in confocal laser scanning images and was measured using FACS and MRI experiments. Compared to the vancomycin conjugates the ramoplanin conjugates showed much weaker and slower uptake. Additionally, uptake of the ramoplanin conjugates led to strong membrane disruption and cell death.
authors: Sumbla
authors: S
authors: Sheikh
authors: Alexander
authors: A
authors: Sturzu
authors: Hubert
authors: H
authors: Kalbacher
authors: Uwe
authors: U
authors: Klose
authors: Thomas
authors: T
authors: Nagele
authors: Bushra
authors: B
authors: Amin
authors: Martin
authors: M
authors: Deeg
authors: Marius
authors: M
authors: Horger
authors: Ulrike
authors: U
authors: Ernemann
authors: Department of Neuroradiology, University of Tübingen, Hoppe-Seyler-Str.3, 72076 Tübingen, Germany. sumblafarooq@yahoo.com.
authors: Stefan
authors: S
authors: Heckl
mesh_terms: D045744:Cell Line, Tumor; D047630:Depsipeptides / Q000138:chemical synthesis / Q000737:chemistry*; D003952:Diagnostic Imaging; D005434:Flow Cytometry; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D006801:Humans; D018613:Microscopy, Confocal
chemical_list: D047630:Depsipeptides; D005456:Fluorescent Dyes; C041438:ramoplanin