Salvianolic acid A suppress lipopolysaccharide-induced NF-κB signaling pathway by targeting IKKβ.

Salvianolic acid A, an active compound present in Salvia miltiorrhiza, is a phenolic carboxylic acid derivative, ((2R)-3-(3,4-Dihydroxyphenyl)-2-[(E)-3-[2-[(E)-2-(3,4-dihydroxyphenyl) ethenyl]-3,4-dihydroxyphenyl] prop-2-enoyl]oxypropanoic acid). The present study was performed to investigate the underlying mechanisms of anti-inflammatory effects with salvianolic acid A, specially focused on nuclear factor κB (NF-κB) signaling pathway by targeting the IκB kinase β (IKKβ). The effect of salvianolic acid A for IKKβ activity was analyzed using an immobilized metal affinity for phosphochemicals (IMAP)-based time-resolved fluorescence resonance energy transfer (TR-FRET) assay. The underlying mechanisms of salvianolic acid A were examined using lipopolysaccharide (LPS)-stimulated RAW264.7 cells. IKKβ studies based on IMAP-TR-FRET showed that salvianolic acid A possesses a potent IKKβ inhibitory activity with Ki value of 3.63 μM in an ATP-noncompetitive manner. Pretreatment with salvianolic acid A (10, 30 μM) decreased LPS-induced expression of iNOS and COX-2, thereby inhibiting production of nitric oxide and prostaglandin E(2), respectively. In addition, salvianolic acid A (10, 30 μM) also attenuated the LPS-induced IκBα phosphorylation and degradation, and NF-κB translocation. These results suggest that salvianolic acid A modulates NF-κB-dependent inflammatory pathways through IKKβ inhibition and these anti-inflammatory effects will aid in understanding the pharmacology and mode of action of salvianolic acid A.