Eremostachiin: a new furanolabdane diterpene glycoside from Eremostachys glabra

Abstract

The reversed-phase preparative HPLC analysis of the methanol extract of the rhizomes of Eremostachys glabra (Lamiaceae) led to the isolation of two furanolabdane diterpene glycosides, phlomisoside II, and β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl ester of phlomisoic acid (named eremostachiin), the latter being a novel natural product. The structure of the new compound has been elucidated unambiguously by HRMS and a series of 1D- and 2D-NMR spectroscopic techniques. The free radical scavenging activity of these compounds was assessed using the DPPH assay.

Keywords:

• Eremostachys glabra
• Labiatae
• Lamiaceae
• Eremostachiin
• Furanolabdane
• Diterpene
• DPPH
• Antioxidant

Acknowledgements

We thank EPSRC National Mass Spectrometry Service Centre (Department of Chemistry, University of Wales Swansea, Swansea, Wales, UK) for MS analyses. One of us (AD) thanks the Ministry of Health and Medical Education, Iran, and the Tabriz University of Medical Sciences, Tabriz, Iran, for a postdoctoral award.