Flavonoid Constituents from Spiranthes australis LINDL.

Chemical investigation of the whole plant of Spiranthes australis (R. BROWN) LINDL. resulted in the isolation and characterization of three new flavonoid constituents, 5-hydroxy-4'-[(2-isopentenyl)oxy]-3,7,3'-trimethoxyflavone (1), 3-O-{[O-beta-D-xylopyranosyl]-(1 -> 2)-beta-D-glucopyranosyl}-8-(p-hydroxy-benzyl)-kaempferol (2) and 3-O-{O-[2-O-(E)-p-coumaroyl-beta-D-xylopyranosyl]- (1 -> 2)-beta-D-glucopyranosyl}-8-(p-hydroxy-benzyl)-kaempferol (3), together with six known flavonoid compounds. The structures of new compounds were determined on the basis of spectroscopic analysis, including HR-ESI-MS, 1D- and 2D-NMR techniques and chemical methods.