Anti-inflammatory Flavonoid C-Glycosides from Piper aduncum Leaves.

Four new compounds, acacetin 8-C-[-D-apiofuranosyl-(1 → 2)--D-glucopyranoside] (), 7-methoxyacacetin 8-C-[-D-apiofuranosyl-(1 → 3)--D-glucopyranoside] (), 7-methoxyacacetin 8-C-[-D-glucopyranosyl-(1 → 2)--D-glucopyranoside] (), and 4‴-O-acetylacacetin 8-C-[-L-rhamnopyranosyl-(1 → 2)--D-glucopyranoside] (), along with ten known compounds (-), were isolated from leaves. The effects of these compounds on lipopolysaccharide-induced expression of the proinflammatory cytokines IL-12 p40, IL-6, and TNF- in bone marrow-derived dendritic cells were evaluated. Compounds , and - inhibited the production of both IL-12 p40 and IL-6, with IC values ranging from 0.35 ± 0.01 to 1.40 ± 0.04 µM and 1.22 ± 0.02 to 3.79 ± 0.10 µM, respectively. Compounds and only showed strong inhibition effects on the production of IL-12 p40, with IC values of 2.76 ± 0.08 and 0.39 ± 0.05 µM, respectively. However, all compounds showed weak activity or no activity on TNF- production at the tested concentrations.