Flavonol dimers from callus cultures of Dysosma versipellis and their in vitro neuraminidase inhibitory activities

Abstract A chemical investigation of callus cultures of Dysosma versipellis led to the isolation of five new flavonol dimers, dysoverines A − E ( 1  −  5 ), together with 12 known compounds ( 6  −  17 ). The structures of new compounds were determined by the extensive spectroscopic data analyses. The biosynthetic pathway of the new compounds was proposed to involve O -methylation, prenylation, and Diels–Alder cycloaddition, which successively occurred in cultured plant cells. Compounds 1  −  17 exhibited in vitro neuraminidase inhibitory activities with the IC 50 values of 31.0 − 93.9 μM.