Flavonoids from <i>Lindera glauca</i> Blume as low-density lipoprotein oxidation inhibitors

<div><p>In order to identify antioxidant flavonoids from <i>Lindera glauca</i> Blume, we performed phytochemical analysis of <i>L</i>. <i>glauca</i> Blume heartwood and isolated eight flavonoids – lindeglaucol (<b>1</b>), lindeglaucone (<b>2</b>), cilicicone B (<b>3</b>), tamarixetin 3-<i>O</i>-α-L-rhamnoside (<b>4</b>), procyanidin A2 (<b>5</b>), cinnamtannin B1 (<b>6</b>), cinnamtannin D1 (<b>7</b>), and procyanidin A1 (<b>8</b>) – through repeated column chromatography over silica gel (SiO<sub>2</sub>), octadecyl silica gel (ODS) and Sephadex LH-20. The chemical structures of compounds <b>1</b>–<b>8</b> were elucidated from spectroscopic data (NMR, IR and MS). The low-density lipoprotein oxidation inhibitory activities of the isolated compounds were evaluated <i>in vitro</i> by using the thiobarbituric acid reactive substances assay. Compounds <b>5</b>–<b>8</b> exhibited high inhibition activity, comparable to the positive control butyl hydroxyl toluene. Compounds <b>2</b> and <b>3</b> were slightly less active, while <b>1</b> and <b>4</b> expressed low activity.</p></div>