Mass spectrometry guided isolation of chlorinated aromatic glycosides from the tubers of Hypoxis aurea

Abstract

Twelve chlorinated aromatic glycosides were isolated from Hypoxis aurea by mass spectrometry guided isolation. • Twelve chlorinated aromatic glycosides were isolated from Hypoxis aurea tubers. • The chlorine containing fractions were detected by using HR-ESI-TOF mass spectrometry. • This study added the typical profile of the secondary metabolites to the genus Hypoxis. High resolution electrospray time-of-flight mass spectrometric analysis was applied as a guiding tool for selection of the chlorine containing fractions by their characteristic clusters of isotopic molecular ion peaks in mass spectra. Twelve target-compounds, chlorinated aromatic glycosides were carried out and identified from the methanolic extract of Hypoxis aurea tubers by chromatographic methods. Hypoxichlorosides A–F ( 3 , 6 , 9−12 ) were found to be undescribed compounds. Curculigine A ( 1 ), curculigine B ( 2 ), curculigine E ( 4 ), curculigine J ( 5 ), 2,4,6-trichloro-3-methoxy-5-methylphenyl 1- O -β- d -glucopyranosyl-(1→6)-β- d -glucopyranoside ( 7 ) and curculigine C ( 8 ) were isolated for the first time from this species. The structure determinations were considered based on the spectroscopic evidence including 1D and 2D NMR experiments.