Antiviral flavonoid-type C-glycosides from the flowers of Trollius chinensis

Two new flavonoid-type C-glycosides, trollisin I (=(IS)-1,5-anhydro-1-[2-(3,4-dihydroxyphenyl)-5hydroxy-7-nietlioxy-4-oxo4H-[1]benzopyran-8-yl]-2-O-(2-methylbutanoyl)-D-glucitol; 1) and its 2-O-benzoyl congener trollisin II (2), were isolated from Trollius chinensis BUNGE, together with the two known compounds 2 ''-O-(2 '''-methylbutanoyl)isoswertisin (3) and vitexin galactoside (4). All compounds were identified by HR-ESI-MS and in-depth NMR-spectroscopic analyses. In antiviral assays, compound 3 was found to be moderately active towards influenza virus A.