Three new compounds: 2R,3R-pterosin L 3-O-β-D-glucopyranoside (>1), β-D-xylopyranosyl(1→2)-7-O-benzoyl-β-D-glucopyranoside (>2) and 4-O-benzoyl-β-D-xylo-pyranosyl(1→2)-7-O-benzoyl-β-D-glucopyranoside (>3), together with nine known compounds, were isolated from the ethyl acetate extract of Pteris ensiformis. 5-[2-Hydroxyethylidene]-2(5H)-furanone (>4), which had been synthesized, was isolated from natural sources for the first time. The structures of all isolated compounds were determined on the basis of mass and spectroscopic evidence. Compound >1 and pterosin B (>5) show cytotoxicity against HL 60 cells (human leukemia) with the IC50 values of 3.7 and 8.7 μg/mL, respectively.
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