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

Five sulfonated and sulfated lignans/neolignans (1-5), together with a neolignan analogue (6), were isolated from an aqueous extract of the Isatis indigotica 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, 1 and 2 are sulfonated 7,9'-epoxylignans, while 3-5 are either sulfated or sulfonated 4',7-epoxy-8,3'-neolignans. In the preliminary bioassay, 2 and 3 exhibited moderate inhibitory activities against TGF-β induced HSC-T6 cell activation.