Studies on the phenylethanoid glycosides with anti-complement activity from Paulownia tomentosa var. tomentosa wood

Four epimeric phenylethanoid glycosides, including a new one, R,S--ethoxy--(3,4-dihydroxyphenyl)-ethyl-O--l-rhamnopyranosyl(13)--d-(6-O-E-caffeoyl)-glucopyranoside named isoilicifolioside A (1), and three known compounds, ilicifolioside A (2), campneoside II (3), and isocampneoside II (4), were isolated from Paulownia tomentosa var. tomentosa wood. The structures of the four compounds were elucidated by the interpretation of 1D and 2D NMR and MS spectra. This is the first report of the chemical profile of this tree. Compounds 1-4 exhibited excellent anti-complement activity with IC50 values less than 74M, compared with tiliroside (IC50=104M) and rosmarinic acid (IC50=182M) that were used as positive controls.