Sulfonated and sulfated lignans/neolignans from an aqueous extract of <i>Isatis indigotica</i> roots

Five sulfonated and sulfated lignans/neolignans (<b>1</b>–<b>5</b>), together with a neolignan analogue (<b>6</b>), were isolated from an aqueous extract of the <i>Isatis indigotica</i> roots (ban lan gen). Their structures were determined by spectral data analysis in combination with electronic circular dichroism (ECD) and NMR calculations. Among the isolates, <b>1</b> and <b>2</b> are sulfonated 7,9′-epoxylignans, while <b>3</b>–<b>5</b> are either sulfated or sulfonated 4′,7-epoxy-8,3′-neolignans. In the preliminary bioassay, <b>2</b> and <b>3</b> exhibited moderate inhibitory activities against TGF-<i>β</i> induced HSC-T6 cell activation.