Antiviral stereoisomers of 3,5-bis(2-hydroxybut-3-en-1-yl)-1,2,4-thiadiazole from the roots of Isatis indigotica

Four stereoisomers of 3,5-bis(2-hydroxybut-3-en-1-yl)-1,2,4-thiadiazole, named insatindigothiadiazoles A–D (1a–1d), were isolated from the roots of Isatis indigotica. Their structures were determined by spectroscopic analysis; specifically, the absolute configurations were assigned by using the MPA determination rule based on ΔδRS values of MPA esters, and supported by electronic CD (ECD) calculations. Proposed biosynthetic pathways and preliminary investigations of the biological activities of 1a–1d against influenza virus A (H3N2), Coxsackie virus B3, and/or HSV-1 are also discussed.

Graphical abstractFour stereoisomers of 3,5-bis(2-hydroxybut-3-en-1-yl)-1,2,4-thiadiazole (1a–1d) were isolated from the roots of Isatis indigotica. Their structures including absolute configurations were determined by spectroscopic analysis combined with application of the MPA determination rule based on ΔδRS values of MPA esters. Postulated biosynthetic pathways of 1a–1d were discussed. The four stereoisomers exhibited selective antiviral activities against influenza virus A (H3N2), Coxsackie virus B3, and/or HSV-1, while selectivity was highly dependent upon the configurations.Figure optionsDownload full-size imageDownload as PowerPoint slide