Stilbenes in Carex acuta and Carex lepidocarpa .

Stilbenes in the roots of Carex acuta and Carex lepidocarpa were studied. Root samples were extracted with 100% methanol and analyzed by HPLC and LC-MS. In this way, trans -resveratrol dimers ( m / z 455 Da [M + H] + ), trimers ( m / z 681 Da [M + H] + ) and tetramers ( m / z 907 Da [M + H] + ) were identified in the extracts. Using LC-NMR in stop-flow mode, pallidol and trans -ε-viniferin as dimers were identified. After the separation of individual peaks and their measurement by 1 H NMR, cis and trans -miyabenol A as a tetramer and cis -miyabenol C as a trimer were identified. In the case of miyabenol A, it is a chromatographically inseparable mixture of cis and trans isomers in the ratio of 2:3 according to 1 H NMR measurement. In the case of cis -miyabenol C, the Z-trans-trans -miyabenol C configuration was confirmed. The remaining unidentified peak with a practically identical UV-VIS spectrum to that of cis -miyabenol C is most likely another isomer of miyabenol C.