Quantitation of phenylpropanoids and iridoids in insulin-sensitising extracts of Leonurus sibiricus L. (Lamiaceae).
BACKGROUND
Leonurus sibiricus L. is regularly used in traditional Mongolian medicine including for the treatment of symptoms of diabetes mellitus.


OBJECTIVE
To provide a validated quantitation method for the quality control of Leonurus sibiricus and to prove in vitro insulin-sensitisation, thereby supporting the traditional use of Leonurus sibiricus.


METHODS
Pulverised Leonurus sibiricus material was either extracted with methanol or methanol:water (25:75, v/v). HPLC-CAD (charged aerosol detector) separations were performed on a Luna Phenyl-Hexyl column with water and acetonitrile (both modified with 0.1% formic acid) as mobile phase. Gradient elution was employed using theophylline as internal standard. Tentative peak identification was facilitated by HPLC-MS. Validation was carried out according to ICH (International Conference on Harmonisation) guidelines. Potential insulin-sensitisation of accordant extracts was assessed in glucose uptake experiments in C2C12 myocytes and protein tyrosine phosphatase 1B (PTP1B) enzyme assays.


RESULTS
Thirty-six compounds were tentatively identified based on their retention times, UV spectra, MS fragments and data from literature. They comprise phenolcarboxylic acids, flavonoids, iridoid glycosides, and phenylpropanoids, among which acetylharpagide, ajugoside, lavandulifolioside, and verbascoside were selected for quantitation. The methanol extract contained 0.42% combined iridoids, and 1.58% combined phenylpropanoids. Validation showed good accuracy, intermediate precision and robustness. The methanol extract of Leonurus sibiricus led to a 1.5 fold increase in insulin-stimulated cellular glucose uptake and inhibition of PTP1B by 40% at a concentration of 10 µg/mL.


CONCLUSIONS
HPLC-CAD analysis allowed sensitive quantitation of the selected marker compounds in Leonurus sibiricus, thereby providing a reliable tool for its quality control.
Department of Pharmacognosy, University of Vienna, Althanstraße 14, A-1090, Vienna, Austria.
Anna
A
Pitschmann
Department of Pharmacognosy, University of Vienna, Althanstraße 14, A-1090, Vienna, Austria.|Department of Pharmaceutical Chemistry, University of Vienna, Althanstraße 14, A-1090, Vienna, Austria.
Martin
M
Zehl
Department of Pharmacognosy, University of Vienna, Althanstraße 14, A-1090, Vienna, Austria.
Elke
E
Heiss
School of Pharmacy and Biomedicine, Mongolian National University of Medical Science, Ulaanbaatar, PO 48 Box 111, Mongolia.
Sodnomtseren
S
Purevsuren
Department of Pharmaceutical Chemistry, University of Vienna, Althanstraße 14, A-1090, Vienna, Austria.
Ernst
E
Urban
Department of Pharmacognosy, University of Vienna, Althanstraße 14, A-1090, Vienna, Austria.
Verena M
VM
Dirsch
Department of Pharmacognosy, University of Vienna, Althanstraße 14, A-1090, Vienna, Austria.
Sabine
S
Glasl
D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005947:Glucose / Q000378:metabolism; D005960:Glucosides / Q000032:analysis; D007004:Hypoglycemic Agents / Q000032:analysis / Q000494:pharmacology*; D039823:Iridoids / Q000032:analysis*; D031332:Leonurus / Q000737:chemistry*; D013058:Mass Spectrometry; D056785:Medicine, Mongolian Traditional; D051379:Mice; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D009844:Oligosaccharides / Q000032:analysis; D010636:Phenols / Q000032:analysis; D010936:Plant Extracts / Q000032:analysis* / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry; D011422:Propionates / Q000032:analysis / Q000737:chemistry; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D011714:Pyrans / Q000032:analysis; D015203:Reproducibility of Results; D059808:Polyphenols
D005947:Glucose; D005960:Glucosides; D007004:Hypoglycemic Agents; D039823:Iridoids; D009844:Oligosaccharides; D010636:Phenols; D010936:Plant Extracts; D011422:Propionates; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D011714:Pyrans; C424543:lavandulifolioside; C058956:acteoside; D059808:Polyphenols; C477173:ajugoside; C077626:8-O-acetylharpagide; C516609:Ptpn1 protein, mouse
Leonurus sibiricus L; PTP1B inhibition; charged aerosol detector; iridoids; phenylpropanoids; validation