Flavonoid glycosides from Rubus chingii Hu fruits display anti-inflammatory activity through suppressing MAPKs activation in macrophages

Rubus chingii Hu has been used as a functional food for a long time. This work was aimed to identify the anti-inflammatory ingredients from R. chingii by an activity-guided isolation. The ethanol extracts of R. chingii were partitioned into petroleum ether, ethyl acetate, butanol and water fractions, and the ethyl acetate fraction exhibited excellent anti-inflammatory activity. Five flavonoid glycosides were isolated from the ethyl acetate fraction based on anti-inflammatory assay-guided purification, which were identified as quercitrin, hyperoside, tiliroside, astragalin and kaempferol 3-rutinoside. The inhibitory effects of extract fractions and compounds on NO production in LPS-stimulated macrophage RAW 264.7 cells were evaluated. The five flavonoid glycosides displayed different degrees of anti-inflammatory activity, among which tiliroside showed stronger activity than others. Further analysis showed that the anti-inflammatory activity of tiliroside might be exerted through inhibiting the activation of ERK and JNK to decrease NO and pro-inflammatory cytokines (TNF-α, iNOS and IL-6) production.