Four new phenolic compounds from stems and leaves of <i>Hemerocallis citrina</i> (Daylily)

Four new phenolic compounds, hemerodiphenylethanes A–D (1–4), along with eight known compounds methyl 2,4-dihydroxy-6-[2-(4-hydroxyphenyl) ethyl] benzoate (5), methyl 2,4-dihydroxy-6-(4-hydroxyphenethyl)-3-methylbenzoate (6), neochlorogenic acid (7), isoquercetin (8), isorhamnetin-3-O-β-D-galactoside (9), velutin (10), rutin (11), and (+)-syringaresinol (12), were isolated from the stems and leaves of Hemerocallis citrina Baroni (Daylily). Their structures were elucidated based on HR-ESI-MS, 1D- and 2D-NMR spectra, and ECD calculations. Among them, both compounds 10 and 12 were isolated from the genus Hemerocallis, and compounds 5 and 6 were isolated from this plant species for the first time. These compounds showed antioxidant activity as determined by IC50 values of DPPH and ABTS+ in a radical scavenging experiment.