title: Evaluation of the inhibition effect of thiolated poly(acrylates) on vaginal membrane bound aminopeptidase N and release of the model drug LH-RH.
abstract: The purpose of this study was to evaluate the inhibitory effect of thiolated carbopol 974P (carb-cys) on the enzymatic activity of vaginal aminopeptidase N in-vitro. Mediated by a carbodiimide, L-cysteine was covalently linked to carbopol 974P. Depending on the weight ratio of polymer to cysteine during the coupling reaction, resulting conjugates displayed 31.3-54.4 micromol thiol groups per g polymer. The inhibitory effect of carb-cys conjugates was evaluated towards isolated aminopeptidase N and aminopeptidase-N-like activity of excised vaginal mucosa covered with native mucus, respectively. Enzymatic activity was assayed spectrophotometrically using L-leucine-p-nitroanilide (L-leu-pNA) as a synthetic substrate. Carb-cys thereby showed a significantly higher inhibitory effect than unmodified polymer towards both isolated enzyme and vaginal mucosa. Moreover, enzyme inhibition was strongly dependent on the amount of thiol groups being immobilised. The more thiol groups available the higher was the inhibitory effect. Due to its additional high cohesive properties and the possibility of a sustained drug release, which could be shown for the model drug LH-RH, carb-cys appears interesting for the development of vaginal peptide drug-delivery systems.
authors: Institute of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Austria. Claudia.Valenta@univie.ac.at
authors: Claudia
authors: C
authors: Valenta
authors: Michaela
authors: M
authors: Marschütz
authors: Christiane
authors: C
authors: Egyed
authors: Andreas
authors: A
authors: Bernkop-Schnürch
mesh_terms: D000179:Acrylates / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D018826:CD13 Antigens / Q000037:antagonists & inhibitors*; D002417:Cattle; D003545:Cysteine / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D004337:Drug Carriers / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000737:chemistry*; D066298:In Vitro Techniques; D009092:Mucous Membrane / Q000201:enzymology / Q000378:metabolism; D014621:Vagina / Q000201:enzymology* / Q000378:metabolism; D014622:Vaginal Creams, Foams, and Jellies
chemical_list: D000179:Acrylates; D004337:Drug Carriers; D004791:Enzyme Inhibitors; D014622:Vaginal Creams, Foams, and Jellies; C117167:carbopol 974P NF; D007987:Gonadotropin-Releasing Hormone; D018826:CD13 Antigens; D003545:Cysteine