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

Four new phenolic compounds, hemerodiphenylethanes A-D (<b>1-4</b>), along with eight known compounds methyl 2,4-dihydroxy-6-[2-(4-hydroxyphenyl) ethyl] benzoate (<b>5</b>), methyl 2,4-dihydroxy-6-(4-hydroxyphenethyl)-3-methylbenzoate (<b>6</b>), neochlorogenic acid (<b>7</b>), isoquercetin (<b>8</b>), isorhamnetin-3-O-β-D-galactoside (<b>9</b>), velutin (<b>10</b>), rutin (<b>11</b>), and (+)-syringaresinol (<b>12</b>), were isolated from the stems and leaves of <i>Hemerocallis citrina</i> Baroni (Daylily). Their structures were elucidated based on HR-ESI-MS, 1D- and 2D-NMR spectra, and ECD calculations. Among them, both compounds <b>10</b> and <b>12</b> were isolated from the genus <i>Hemerocallis</i>, and compounds <b>5</b> and <b>6</b> 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.