Liquiritin, a flavone compound from licorice, inhibits IL-1β-induced inflammatory responses in SW982 human synovial cells

- Liquiritin is a flavone compound derived from the sweetening agent licorice.
- First report on anti-inflammatory effects of liquiritin in human synovial cells.
- Liquiritin reduced IL-1β-induced IL-6 and IL-8 production in SW982 cells.
- Activation of p38, JNK, AP-1, AMPK and NF-κB were inhibited by liquiritin.

Liquiritin is one of flavone compounds derived from licorice, a common flavoring and sweetening agent in food products. This study investigated the effects and mechanisms of liquiritin in interleukin (IL)-1β-stimulated SW982 human synovial cells, which is a useful tool to study the inflammatory response of rheumatoid arthritis (RA). The SW982 cells were pretreated with various concentrations (0, 10 and 40 μM) of liquiritin, followed by IL-1β (10 ng/mL) stimulation. Liquiritin significantly inhibited protein and mRNA levels of inflammatory cytokines IL-6 and IL-8 in IL-1β-stimulated SW982 cells. Liquiritin suppressed IL-1β-induced phosphorylation of p38, c-jun N-terminal kinase (JNK), and adenosine monophosphate-activated protein kinase (AMPK), inhibited p-c-Jun activation and decreased p65 protein translocation into the nucleus induced by IL-1β. These results indicate that liquiritin exerts an anti-inflammatory effect via modulating JNK, p38, activator protein-1 (AP-1), AMPK and nuclear factor-κB (NF-κB) pathways in IL-1β-induced human synovial cells.

The aim of this study is to elucidate effects and mechanisms of liquiritin, a flavone compound derived from licorice, in IL-1β-stimulated SW982 human synovial cells. Our data demonstrate that liquiritin significantly inhibits the expression of IL-6 and IL-8 via inhibition of JNK, p38 MAPK, AP-1, AMPK and NF-κB signaling in IL-1β-induced SW982 cells. These findings support the potential use of liquiritin as an effective therapeutic agent for rheumatoid arthritis treatment.81