title: Optimisation of an in vitro procedure for the determination of the enzymatic inhibition potency of multifunctional polymers.
abstract: An in vitro procedure for the determination of the inhibition potency of multifunctional polymers towards the proteolytic enzyme trypsin was optimised. Carbopol((R)) 934P was used as the reference polymer. The enzymatic reaction was optimised and the HPLC method was validated. The optimal substrate concentration and enzymatic activity were determined aiming at extracting the linear or steady-state part of the metabolite concentration versus time curve of the enzymatic degradation reaction. A substrate concentration of 20 mmol/l N-alpha-benzoyl-L-arginine-ethylester and an enzymatic activity of 30 enzymatic units trypsin/ml were used. The degree of trypsin inhibition was expressed by the inhibition factor (IF), defined as the ratio of the enzymatic reaction rate without a polymer (control) to the reaction rate in the presence of a polymer. During the optimisation of the trypsin inhibition assay, formation of an ion complex between the substrate and the poly(acrylic acid) was observed. The complex formation was concentration dependent, but the influence on the enzymatic reaction was negligible as long as an excessive substrate concentration was present in the reaction medium. The optimised method allows to characterize, evaluate and compare the in vitro trypsin inhibition strength for most multifunctional polymers.
authors.affiliation: Laboratory of Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Ghent University, Harelbekestraat 72, B-9000, Gent, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Ameye
authors.forename: J
authors.initials: J
authors.lastname: Voorspoels
authors.forename: J P
authors.initials: JP
authors.lastname: Remon
authors.forename: J
authors.initials: J
authors.lastname: Demeester
authors.forename: S C
authors.initials: SC
authors.lastname: De Smedt
mesh_terms: D000180:Acrylic Resins; D001120:Arginine / Q000031:analogs & derivatives; D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005079:Excipients; D007700:Kinetics; D011108:Polymers / Q000494:pharmacology*; D014361:Trypsin Inhibitors / Q000494:pharmacology
chemical_list: D000180:Acrylic Resins; D004791:Enzyme Inhibitors; D005079:Excipients; D011108:Polymers; D014361:Trypsin Inhibitors; C006903:carbopol 940; D001120:Arginine; C009727:benzoylarginine ethyl ester