In vitro anti-influenza virus activity of isoquinoline alkaloids from thalictrum species

The in vitro anti-influenza virus effects of some isoquinoline alkaloids, isolated from Thalictrum species (Ranunculaceae), growing in Mongolia and Sweden have been studied. (-)-thalimonine (Thl) and (-)-thalimonine N-oxide, isolated from the Mongolian plant T. simplex, inhibited markedly the influenza virus reproduction in vitro; thalictuberine N-oxide was less effective. The synthetic analogues of Thl as well as the rest of the tested alkaloids, isolated from T. foetidum and T. flavum, were not active. At a concentration range between 0.1 - 6.4 microM Thl inhibited viral reproduction in a selective and specific way.