Isobavachalcone suppresses expression of inducible nitric oxide synthase induced by Toll-like receptor agonists

Toll-like receptors (TLRs) play an important role by recognizing many pathogen-associated molecular patterns and inducing innate immunity. Dysregulated activation of TLR signaling pathways induces the activation of various transcription factors such as nuclear factor-κB, leading to the induction of pro-inflammatory gene products such as inducible nitric oxide synthase (iNOS). The present study investigated the effect of isobavachalcone (IBC), a natural chalcone component of Angelica keiskei, on inflammation by modulating iNOS expression induced by TLR agonists in murine macrophages. IBC suppressed iNOS expression induced by macrophage-activating lipopeptide 2-kDa, polyriboinosinic polyribocytidylic acid, or lipopolysaccharide. These results indicate the potential of IBC as a potent anti-inflammatory drug.

► Inflammation is involved in numerous diseases.
► Toll-like receptors (TLR) play a significant role in the induction of innate immune responses.
► Isobavachalcone (IBVC) suppressed iNOS expression induced by MALP-2 (TLR2 and TLR6), Poly[I:C] (TLR3), and LPS (TLR4).
► These results suggest that IBVC can regulate TLRs signaling pathways leading to decreased inflammatory gene expression.