Bioactive substances from invasive knotweed species.
Knotweed is in Europe and America a highly invasive plant, originating from Asia. Three different taxons are identified in Europe, namely Japanese knotweed (Fallopia japonica), Sakhalin knotweed (Fallopia sachalinensis) and Bohemian knotweed (Fallopia × bohemica). The best-known among them is F. japonica that has been since ancient times used in traditional Chinese medicine for treatment of different kind of diseases (e.g. inflammatory diseases, hepatitis, tumors, burns and hyperlipidemia). Several studies have recently been performed to confirm that the Japanese knotweed extract possess several different bioactivities, namely antioxidant, antidiabetic, antiviral, antibacterial, and antimycotic activity. It was shown that many different bioactive components are responsible for this. However, much less studies have been performed on the other two knotweed species, particularly on the Bohemian knotweed, which is the most widely spread due to its highest invasiveness among the three taxons. The results of our study confirmed antioxidant and antimicrobial activities of extracts obtained from different tissues (rhizomes, leaves, stalks and flowers) of all three knotweed species.