Studies on natural products that can alleviate the inflammatory response of macrophages caused by endotoxin (lipopolysaccharide) continue. This study investigated the anti-inflammatory activity of baicalin related to macrophage activation caused by lipopolysaccharide (LPS). Baicalin is a flavone glycoside found in plants such as Scutellaria baicalensis and Scutellaria lateriflora belonging to the genus Scutellaria. The multiplex cytokine assay (MCA), Griess reagent assay, fluo-4 calcium assay, dihydrorhodamine 123 (DHR123) assay, quantitative RT-PCR, and flow cytometry were performed using RAW 264.7 mouse macrophages. The MCA revealed that baicalin significantly decreased the production of interleukin (IL)-6, granulocyte colony-stimulating factor (G-CSF), vascular endothelial growth factor (VEGF), macrophage inflammatory protein (MIP)-1α, MIP-1β, MIP-2, and RANTES in LPS-stimulated RAW 264.7 macrophages at concentrations of 10, 25, and 50 μM. The DHR123 assay showed that baicalin significantly inhibited reactive oxygen species generation in LPS-stimulated RAW 264.7 macrophages. Flow cytometry revealed that baicalin significantly reduced the levels of phosphorylated p38 MAPK and Fas in LPS-stimulated RAW 264.7 macrophages. Baicalin also inhibited the mRNA expression levels of inflammatory genes such as Chop, Fas, Nos2, Ptgs2, Stat1, c-Jun, c-Fos, and At1a. The IC50 values of baicalin for IL-6, TNF-α, G-CSF, VEGF, interferon gamma-induced protein 10 (IP-10), leukemia inhibitory factor (LIF), lipopolysaccharide-induced CXC chemokine (LIX), MIP-1α, MIP-1β, MIP-2, RANTES, nitric oxide, intracellular calcium, and hydrogen peroxide were 591.3, 450, 1719, 27.68, 369.4, 256.6, 230.7, 856.9, 1326, 1524, 378.1, 26.76, 345.1, and 32.95 μM, respectively. Baicalin modulated the inflammatory response of macrophages activated by LPS via the calcium-CHOP pathway.
Keywords: anti-inflammation; baicalin; calcium; chop; cytokine; lipopolysaccharide; macrophage; nitric oxide; p38 MAPK.