The Stilbene and Catechin Content of the Spring Sprouts of Reynoutria Species

Knotweed rhizomes and young sprouts are used in a traditional Asian medicine. Because knotweed rhizomes contain large amount of stilbenes and catechins, the main objective of this study was analysis of selected phenolic compounds, including stilbenes and catechins, in young spring sprouts of the knotweed genus (Japanese knotweed (Reynoutria japonica), Giant knotweed (Reynoutria sachalinensis), and their hybrid Bohemian knotweed (Reynoutria × bohemica)). Plant material was collected in the Czech Republic. Dry sprouts were extracted with 90% methanol and phenolic compounds were analysed by HPLC–DAD. The sprouts of all three species contain large amounts of resveratrol, piceid, catechin, and epicatechin but the total quantity of these phenolic compounds was less than in the rhizomes.