title: Coupling of a high-resolution monoamine oxidase-A inhibitor assay and HPLC-SPE-NMR for advanced bioactivity profiling of plant extracts.
abstract: BACKGROUND
  Depression is a mental disease causing large personal and socio-economic problems, and new improved drugs are therefore needed. Selective monoamine oxidase A (MAO-A) inhibitors are potential anti-depressants, but discovering new MAO-A inhibitors from natural sources by bioassay-guided approaches are a lengthy and time-consuming process. New analytical technologies that allow simultaneously chemical and biological screening of extracts are therefore urgently needed.
  
  
  METHODS
  In the present study we describe coupling of a photometric microplate-based high-resolution MAO-A inhibitor assay with a hyphenated system consisting of high-performance liquid chromatography, solid-phase extraction and tube transfer nuclear magnetic resonance (HPLC-SPE-ttNMR). The standard compound clorgyline, and an extract of black pepper (Piper nigrum L.), representing a complex plant matrix, were used for proof-of-concept.
  
  
  RESULTS
  The work with clorgyline showed that the microplate-based high-resolution assay produced MAO-A inhibition profiles that easily allowed detection of submicrogram amounts of this selective MAO-A inhibitor. Furthermore, the HPLC-SPE-ttNMR/high-resolution MAO-A inhibition assay platform allowed identification of piperine and two piperine analogues as the main MAO-A inhibitors in the black pepper petroleum ether extract.
  
  
  CONCLUSIONS
  The HPLC-SPE-ttNMR/high-resolution MAO-A inhibition assay platform is a powerful tool for fast and efficient identification of new MAO-A inhibitors from complex extracts, and promise future advancement in the search for new anti-depressants from natural sources.
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
authors.forename: Clara
authors.initials: C
authors.lastname: Grosso
authors.forename: Anna K
authors.initials: AK
authors.lastname: Jäger
authors.forename: Dan
authors.initials: D
authors.lastname: Staerk
mesh_terms: D000470:Alkaloids / Q000737:chemistry / Q000494:pharmacology / Q000592:standards; D052117:Benzodioxoles / Q000737:chemistry / Q000494:pharmacology / Q000592:standards; D055162:Biocatalysis / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002863:Chromogenic Compounds / Q000378:metabolism; D003010:Clorgyline / Q000737:chemistry / Q000494:pharmacology / Q000592:standards; D004305:Dose-Response Relationship, Drug; D057075:Enzyme Assays / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D008995:Monoamine Oxidase / Q000378:metabolism; D008996:Monoamine Oxidase Inhibitors / Q000032:analysis* / Q000302:isolation & purification / Q000494:pharmacology; D010783:Photometry / Q000379:methods; D029222:Piper nigrum / Q000737:chemistry; D010880:Piperidines / Q000737:chemistry / Q000494:pharmacology / Q000592:standards; D010936:Plant Extracts / Q000737:chemistry*; D053284:Polyunsaturated Alkamides / Q000737:chemistry / Q000494:pharmacology / Q000592:standards; D015203:Reproducibility of Results; D052616:Solid Phase Extraction / Q000379:methods*; D014439:Tyramine / Q000378:metabolism
chemical_list: D000470:Alkaloids; D052117:Benzodioxoles; D002863:Chromogenic Compounds; D008996:Monoamine Oxidase Inhibitors; D010880:Piperidines; D010936:Plant Extracts; D053284:Polyunsaturated Alkamides; D008995:Monoamine Oxidase; D003010:Clorgyline; C008922:piperine; D014439:Tyramine