Baicalein inhibits inflammatory and catabolic gene expression in interleukin-1beta-induced human chondrocytes

Baicalein is a flavone compound isolated from Scutellaria baicalensis Georgi (Huang Qin) which exerts multiple biological effects including anti-inflammatory, anti-apoptotic and anti-tumor. However, there is little known about the effects of baicalein on cathepsins and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) in osteoarthritis (OA). In the present study, we investigated whether baicalein exerts inhibitory effects on ADAMTS and cathepsins. Chondrocytes were cultured in the absence or in the presence of interleukin-1beta (IL-1β) (10 ng/ml) and with or without baicalein (5-50 μM). Nitric oxide (NO) production was determined by Griess reaction. Gene expressions of ADAMTS and cathepsins, inducible nitric oxide synthase (iNOS) were detected by real-time quantitative PCR. We found that baicalein inhibited the IL-1β-induced gene expression of ADAMTS-4, ADAMTS-5, cathepsin K and cathepsin B. In addition, baicalein also suppressed NO production as well as iNOS mRNA level. Our results indicate that baicalein may be considered a possible agent in the treatment of OA.