Diarylheptanoids and flavonoids from Viscum album inhibit LPS-stimulated production of pro-inflammatory cytokines in bone marrow-derived dendritic cells

Three new diarylheptanoids, (3S,5R)-3-hydroxy-5-methoxy-1,7-bis(4- hydroxyphenyl)-6E-heptene (1), (3S,5S)-3-hydroxy-5-methoxy-1,7-bis(4- hydroxyphenyl)-6E-heptene (2), and (3S)-3-hydroxy-1,7-bis(4-hydroxyphenyl)-6E- hepten-5-one (3), four new flavonoid glycosides, 3,7,3′-tri-O- methylquercetin-4′-O-β-d-apiofuranosyl-(1→2)-O-β-d- glucopyranoside (4), 7,3′-di-O-methylquercetin-4′-O-β-d- glucopyranosyl-3-O-[6́-(3-hydroxy-3-methylglutaroyl)]-α-d- glucopyranoside (5), 7,3′-di-O-methylquercetin-4′-O-β-d- glucopyranosyl-3-O-[(6′′′′′→5′′ ′′)-O-1′′′′′-(sinap-4-yl) -β-d-glucopyranosyl-6́-(3-hydroxy-3-methylglutaroyl)] -α-d-glucopyranoside (6), and (2S)-5-hydroxy-7,3′- dimethoxyflavanone-4′-O-β-d-apiofuranosyl-(1→5) -O-β-d-apiofuranosyl-(1→2)-O-β-d-glucopyranoside (9), and 17 known compounds were isolated from the leaves and twigs of Viscum album. Compounds 1, 4, and 19 significantly inhibited LPS-stimulated production of TNF-α, IL-6, and IL-12p40 with IC₅₀ values ranging from 0.09 ± 0.01 to 8.96 ± 0.45 μM. (+)-Medioresinol (13) showed inhibitory effects on LPS-stimulated production of IL-12p40 with an IC ₅₀ value of 2.00 ± 0.15 μM.