Two new secolignans from the roots of Urtica fissa

Two new secolignans, 3,4-trans-3-hydroxymethyl-4-bis(4-hydroxy-3- methoxyphenyl)methyl]butyrolactone (1) and 3,4-trans-3-hydroxymethyl-4- bis(3,4-dimethoxyphenyl)methyl]butyrolactone (2) have been isolated from the roots of Urtica fissa E.Pritz. Their structures were determined on the basis of spectroscopic methods, especially ¹H NMR, ¹³C NMR, 2D NMR, and HR-ESI-MS. The inhibitory effects on N1 and N2, two subtypes of neuraminidases (NAs), of these two compounds were assayed.