title: HPLC method development for the online-coupling of chromatographic Perilla frutescens extract separation with xanthine oxidase enzymatic assay.
abstract: Enzyme-regulatory effects of compounds contained in complex mixtures can be unveiled by coupling a continuous-flow enzyme assay to a chromatographic separation. A temperature-elevated separation was developed and the performance was tested using Perilla frutescens plant extracts of various polarity (water, methanol, ethanol/water). Owning to the need of maintaining sufficient enzymatic activity, only low organic solvent concentrations can be added to the mobile phase. Hence, to broaden the spectrum of eluting compounds, two different organic solvents and various contents were tested. The chromatographic performance and elution was further improved by the application of a moderate temperature gradient to the column. By taking the effect of eluent composition as well as calculated logD values and molecular structure of known extract compounds into account, unknown features were tentatively assigned. The method used allowed the successful observation of an enzymatic inhibition caused by P. frutescens extract.
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall, 85748 Garching, Germany.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Kaufmann
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall, 85748 Garching, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Grassmann
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall, 85748 Garching, Germany. Electronic address: T.Letzel@tum.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Letzel
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D031344:Perilla frutescens / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification*; D014969:Xanthine Oxidase / Q000378:metabolism*
chemical_list: D010936:Plant Extracts; D014969:Xanthine Oxidase
keywords: HPLC method development; Inhibition; Online coupled continuous flow system; Perilla frutescens; Temperature gradient; Xanthine oxidase