Antioxidant and cytotoxic lignans from the roots of <i>Bupleurum chinense</i>

<p>In the search for biologically active compounds from the roots of <i>Bupleurum chinense</i> D C., phytochemical investigation of its ethanol extract led to the isolation and identification of a new 8-<i>O</i>-4′ neolignan glucoside, saikolignanoside A (<b>1</b>), along with eight known lignans (<b>2–9</b>). Their structures were determined on the basis of IR, UV, HRESIMS, and NMR spectroscopic analyses. The antioxidant and cytotoxic effects of isolated compounds were evaluated <i>in vitro</i>. The isolated compounds (IC₅₀ > 200 μM) did not display 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Whereas compounds <b>1–2</b>, <b>5</b>, <b>7,</b> and <b>9</b> exhibited potent 2, 2′-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging properties with IC₅₀ values ranging from 8.34 to 15.24 μM, while compounds <b>3–4</b>, <b>6</b>, <b>8</b> showed moderate properties. In addition, all compounds were evaluated for cytotoxicities against A549, HepG2, U251, Bcap-37, and MCF-7 cell lines. Compounds <b>5</b> and <b>9</b> (IC₅₀< 51.62 μM) possessed stronger cytotoxic activities against all the tested tumor cell lines, compared with the positive control 5-Fluorouracil.</p