title: Prevention of False-Positive Results: Development of an HPTLC Autographic Assay for the Detection of Natural Tyrosinase Inhibitors.
abstract: A simple and rapid high-performance thin-layer chromatography-based autographic assay was established to screen plant extracts for the presence of tyrosinase-inhibiting substances. Three mobile phases were selected for the chromatographic separation of different types of extracts. After development, the plate was sprayed with the substrate solution Levodopa followed by a solution of the enzyme tyrosinase. Several known tyrosinase inhibitors were tested simultaneously as positive controls. They were detected as white spots with white light in remission from the plate as well as with white light transmitted through the plate. Some of the investigated extracts included spots showing a different behaviour; some lipophilic substances appeared as white spots in white light remission but were black in white light transmission. This behaviour, which could lead to false-positive results, was due to poor wettability of the corresponding spots. False-positive results were eliminated by adding Triton X-100 to the Levodopa solution and drying the plate after 10 minutes incubation with a molecular sieve. Tyrosinase inhibitors can be clearly identified as white spots against a dark background in white light remission as well as in white light transmitted through the plate. The established high-performance thin-layer chromatography autographic assay was validated and can be used as a standard method for the detection of tyrosinase inhibitors in plant extracts without causing false-positive results.
authors.affiliation: Institute of Pharmacy/Pharmacognosy, University of Innsbruck, CMBI, CCB - Center of Chemistry and Biomedicine, Innsbruck, Austria.
authors.forename: Judith
authors.initials: J
authors.lastname: Taibon
authors.affiliation: CAMAG Laboratory, Muttenz, Switzerland.
authors.forename: Anita
authors.initials: A
authors.lastname: Ankli
authors.affiliation: Institute of Pharmacy/Pharmacognosy, University of Innsbruck, CMBI, CCB - Center of Chemistry and Biomedicine, Innsbruck, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schwaiger
authors.affiliation: School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland.
authors.forename: Camille
authors.initials: C
authors.lastname: Magnenat
authors.affiliation: Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, University of Athens, Panepistimiopolis Zografou, Athens, Greece.
authors.forename: Vasilik-Ioanna
authors.initials: VI
authors.lastname: Boka
authors.affiliation: School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Simões-Pires
authors.affiliation: Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, University of Athens, Panepistimiopolis Zografou, Athens, Greece.
authors.forename: Naktarios
authors.initials: N
authors.lastname: Aligiannis
authors.affiliation: School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland.
authors.forename: Muriel
authors.initials: M
authors.lastname: Cuendet
authors.affiliation: Department of Pharmacognosy and Natural Products Chemistry, Faculty of Pharmacy, University of Athens, Panepistimiopolis Zografou, Athens, Greece.
authors.forename: Alexios-Leandros
authors.initials: AL
authors.lastname: Skaltsounis
authors.affiliation: CAMAG Laboratory, Muttenz, Switzerland.
authors.forename: Eike
authors.initials: E
authors.lastname: Reich
authors.affiliation: Institute of Pharmacy/Pharmacognosy, University of Innsbruck, CMBI, CCB - Center of Chemistry and Biomedicine, Innsbruck, Austria.
authors.forename: Hermann
authors.initials: H
authors.lastname: Stuppner
mesh_terms: D000363:Agaricales / Q000201:enzymology*; D002855:Chromatography, Thin Layer / Q000379:methods*; D005189:False Positive Reactions; D007980:Levodopa / Q000737:chemistry*; D013058:Mass Spectrometry; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors*; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry*
chemical_list: D010936:Plant Extracts; D007980:Levodopa; D014442:Monophenol Monooxygenase