title: Extracts from Rhododendron ferrugineum do not exhibit grayanotoxin I: an analytical survey on grayanotoxin I within the genus Rhododendron.
abstract: For quantitative determination of grayanotoxin I (1) in plant material, a GC/MS method was developed after trimethylsilyl derivatisation of the analytes. Forskolin (5) was used as an internal standard for quantification. ICH-compliant method validation indicated sufficient specificity, precision, quantitation (15 µg/mL) and detection (5 µg/mL) limits. Regression analysis showed that a non-linear (polynomial) model was preferable to a linear one. For isolation of grayanotoxin I reference material from Rhododendron ponticum leaves, an efficient two-step fast centrifugal partition chromatography isolation protocol is described. A survey of 17 different plant species from the genus Rhododendron revealed high grayanotoxin I content for R. catawbiense, R. ponticum, R. degronianum subsp. yakushimanum, R. × sochadzeae, R. moupinense, R. galactinum, and R. mucronatum var. ripense. The content of this compound in leaf material from R. ponticum decreased rapidly during drying process. Grayanotoxin I was not detected in different batches of fresh leaves and fruits from R. ferrugineum. In contrast to the claims of German health authorities, this traditionally used herb therefore cannot be evaluated as toxic due to the presence of grayanotoxin I.
authors.affiliation: Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Münster, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Lechtenberg
authors.affiliation: Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Münster, Germany.
authors.forename: Frauke
authors.initials: F
authors.lastname: Dierks
authors.affiliation: Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Münster, Germany.
authors.forename: Jandirk
authors.initials: J
authors.lastname: Sendker
authors.affiliation: Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Münster, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Louis
authors.affiliation: Stiftung Bremer Rhododendronpark, Bremen, Germany.
authors.forename: Hartwig
authors.initials: H
authors.lastname: Schepker
authors.affiliation: Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Münster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hensel
mesh_terms: D004224:Diterpenes / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D012044:Regression Analysis; D015203:Reproducibility of Results; D029793:Rhododendron / Q000737:chemistry*
chemical_list: D004224:Diterpenes; D010936:Plant Extracts; C001311:grayanotoxin I