Periodontal disease is an inflammatory disease that affects the destruction of the bone supporting the tooth and connective tissues surrounding it. Periodontal ligament fibroblasts (PDLFs) induce overexpression of matrix metalloproteinase (MMP) involved in periodontal diseaseʼs inflammatory destruction. Osteoclasts take part in physiological bone remodeling, but they are also involved in bone destruction in many kinds of bone diseases, including osteoporosis and periodontal disease. This study examined the effect of baicalin on proteolytic enzymesʼ production and secretion of inflammatory cytokines in PDLFs and RAW 264.7 cells under the lipopolysaccharide (LPS)-induced inflammatory conditions. Baicalin inhibited the expression of the protein, MMP-1 and MMP-2, without affecting PDLFs’ cell viability, suggesting its possibility because of the inhibition of phosphorylation activation of mitogen-activated protein kinase’s p38, and the signal transduction process of nuclear factor κB (NFκB)-related protein. Also, baicalin reduced the expression of MMP-8 and MMP-9 in RAW 264.7 cells. This reduction is thought to be due to the inhibition of the signal transduction process of NFκB-related proteins affected by inhibiting p65RelA phosphorylation. Also, baicalin inhibited the secretion of nitric oxide and interleukin-6 induced by LPS in RAW 264.7 cells. These results suggest that baicalin inhibits connective tissue destruction in periodontal disease. The inhibition of periodontal tissue destruction may be a therapeutic strategy for treating inflammatory periodontal-diseased patients.

Introduction
Materials and Methods
    1. Reagents
    2. A culture of periodontal ligament fibroblasts andRAW 264.7 cells
    3. Cell survival test using methylthiazolyldiphenyltetrazoliumbromide (MTT)
    4. Test by western blot
    5. IL-6 secretion test using ELISA
    6. Nitrite test
    7. Statistical analysis
Results
    1. Expression results of MMP-1 and MMP-2 inperiodontal ligament cells
    2. Baicalin’s effect on MAPK activation in periodontalligament cells
    3. An effect of baicalin on NFκB related activation inperiodontal ligament cells
    4. Expression result of MMP-8 and MMP-9 in RAW264.7 cells
    5. An effect of baicalin on MAPK activation in RAW264.7 cells
    6. An effect of baicalin on NFκB-related activation inRAW 264.7 cells
    7. IL-6 and NO results
Discussion
References

• Seon-Yle Ko(Department of Oral Biochemistry and Institute of Dental Science, Dankook University College of Dentistry) Correspondence to