Lignans and a neolignan from an aqueous extract of Isatis indigotica roots

Four new lignans (1-4) and one new neolignan (5), along with two known lignan derivatives (6 and 7), were isolated from an aqueous extract of the Isatis indigotica root (ban lan gen). Their structures were determined by spectroscopic data analysis, chemical method, and theoretical calculation, for which 1 was proved by single-crystal X-ray diffraction. Compound 2 exhibited antiviral activity against influenza virus A/Hanfang/359/95 (H3N2) with an IC50 value of 11.1 mu M and a selective index (SI) > 9, while 1 and 5 are the first examples of sulfonated lignan and neolignan from nature.

Automated summary

In this study, four new lignans and one new neolignan were isolated from the aqueous extract of Isatis indigotica root, along with two known lignan derivatives. Compound 2 showed antiviral activity against influenza virus and exhibited good selectivity.