Two new phenolic acids from Drynariae Rhizoma

To study the chemical constituents of Drynariae Rhizoma, nine phenolic acids were isolated  from a 70% ethanol extract by using a combination of various chromatographic techniques including column chromatography over silica gel, ODS, Sephadex LH-20, and semi-preparative HPLC.  By spectroscopic techniques including ¹H NMR, ¹³C NMR, 2D NMR, and HR-ESI-MS, these compounds were identified as 4, 4'-dihydroxy-3, 3'-imino-di-benzoic acid (1), protocatechuic acid (2), gallic acid (3), p-hydroxybenzoic acid (4), (E)-caffeic acid (5), ethyl trans-3, 4-dihydroxycinnamate (6), caffeic acid 4-O-β-D-glucopyranoside (7), p-coumaric acid 4-O-β-D-glucopyranoside (8), and 23(S)-12-O-caffeoyl-12-hydroxyllauric acid glycerol ester (9), separately.  Among them, 1 and 9 are new compounds, and 3, 4, and 6 were isolated from Drynaria species for the first time.