Lignan Dimers from Forsythia viridissima Roots and Their Antiviral Effects.

Six new dimeric lignans (1-6) and one new lignan glycoside (16) were isolated from Forsythia viridissima roots along with nine known lignans (7-15). Spectroscopic analyses and chemical methods were used to determine these new structures and their absolute configurations. Among these compounds, dimatairesinol (1) and viridissimaols A-E (2-6) were assigned as dimers of dibenzylbutyrolactone analogues. Furthermore, the isolated compounds were evaluated for their antiviral activities against coxsackievirus B3 (CVB3) and human rhinovirus 1B (HRV1B). In these tests, compounds 12 and 15 showed antiviral effects against CVB3 infection with IC50 values of 15.4 and 36.4 μM, respectively, while 2, 3, 8, and 9 showed activities against HRV1B with IC50 values of 45.7, 47.5, 13.0, and 43.2 μM, respectively.