title: Neoglycoproteins as carriers for antiviral drugs: synthesis and analysis of protein-drug conjugates.
abstract: In order to investigate whether neoglycoproteins can potentially act as carriers for targeting of antiviral drugs to certain cell types in the body, various neoglycoproteins were synthesized using thiophosgene-activated p-aminophenyl sugar derivatives. These neoglycoproteins were conjugated with the 5'-monophosphate form of the antiviral drug AZT. For a proper characterization of these preparations, both protein and drug content have to be determined. Comparison of the Lowry and the Bio-Rad protein assays revealed that for both the neoglycoprotein carriers themselves and the AZTMP conjugates, the Lowry assay yielded the most reliable and reproducible results. It was demonstrated that both the reagent used for drug conjugation (ECDI) as well as the introduction of phenyl-sugar groups in the protein interfered with the analysis of bound nucleotide as based on spectral differences between protein and protein-drug conjugate. Therefore, we developed a rapid HPLC system for determination of the drug-protein coupling ratio through acid hydrolysis of the covalently bound nucleotide. With the ECDI-mediated conjugation of 5'-monophosphate drug derivatives to neoglycoproteins, products with molar ratios of drug to protein ranging from 1.2 to 5.6 were obtained. The drug-neoglycoprotein conjugates appeared to be fairly stable during storage, in lyophilized form, at -20 degrees C. The anti-HIV-1 activity of the neoglycoprotein-drug conjugates, as determined in vitro in MT-4 cells, was shown to be dependent on glycosylation of the albumin and also on the kind of sugar present in the neoglycoprotein. The anti-HIV-1 activity of the AZTMP-mannose-albumin conjugate exceeded that of the parent drug by more than 4 times.
authors.affiliation: Department of Pharmacology & Therapeutics, Groningen University, The Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Molema
authors.forename: R W
authors.initials: RW
authors.lastname: Jansen
authors.forename: J
authors.initials: J
authors.lastname: Visser
authors.forename: P
authors.initials: P
authors.lastname: Herdewijn
authors.forename: F
authors.initials: F
authors.lastname: Moolenaar
authors.forename: D K
authors.initials: DK
authors.lastname: Meijer
mesh_terms: D000998:Antiviral Agents / Q000008:administration & dosage / Q000737:chemistry* / Q000494:pharmacology; D054306:Dideoxynucleotides; D004337:Drug Carriers; D004355:Drug Stability; D006023:Glycoproteins / Q000032:analysis / Q000138:chemical synthesis* / Q000494:pharmacology; D015497:HIV-1 / Q000187:drug effects; D006868:Hydrolysis; D008358:Mannose / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D011506:Proteins / Q000032:analysis; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D013942:Thymine Nucleotides / Q000008:administration & dosage / Q000737:chemistry* / Q000494:pharmacology; D015215:Zidovudine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000998:Antiviral Agents; D054306:Dideoxynucleotides; D004337:Drug Carriers; D006023:Glycoproteins; D011506:Proteins; D012709:Serum Albumin; D013942:Thymine Nucleotides; C067831:zidovudine 5'-monophosphate-mannose-albumin conjugate; C057287:3'-azido-3'-deoxythymidine 5'phosphate; D015215:Zidovudine; D008358:Mannose