Wang Guo-fang, Wu Zhi-fen, Wan Ling, Wang Qin-tao, Chen Fa-ming
Department of Periodontology and Oral Medicine, College of Stomatology, Fourth Military Medical University, Xi'an, China.
Pharmacology. 2006;77(2):71-7. doi: 10.1159/000092853. Epub 2006 Apr 21.
Baicalin is a flavonoid purified from the medicinal plant Scutellaria baicalensis Georgi. It has been reported that baicalin exhibits antibacterial, anti-inflammatory and analgesic effects and can inhibit nuclear factor-kappaB activation. Periodontal disease is a chronic infective disease of the periodontium caused by bacteria present in dental plaque inducing alveolar bone resorption until teeth are lost. Human periodontal ligament (HPDL) is the connective tissue between alveolar bone and tooth. Receptor activator of nuclear factor-kappaB ligand (RANKL), a member of the tumor necrosis factor (TNF) ligand family, plays an important role in osteoclastogenesis from osteoclast precursors to mature osteoclasts. In this study we investigate the effects of baicalin on RANKL protein production and messenger RNA (mRNA) expression induced by IL-1beta in cultured HPDL cells.
To induce RANKL expression, IL-1beta was added to serum-free medium HPDL cells and incubated. Various concentrations of baicalin (0, 0.001, 0.01 and 0.1 microg/ml) were added to the medium and the cells were treated for 0, 12, 24, 48 and 72 h, respectively. RANKL in the cells was detected using immunocytochemistry. The mRNA of RANKL, osteoprotegerin (OPG) and cyclooxygenase-2 (COX-2) were measured by semiquantitative reverse transcription-polymerase chain reaction.
The expression of RANKL at mRNA and protein levels in HPDL cells was stimulated by IL-1beta. Baicalin suppressed IL-1beta-induced RANKL and COX-2 production at a concentration of 0.01 microg/ml. The most prominent effect was observed with 48 h of baicalin treatment. The inhibition of baicalin on the rhIL-1beta-stimulated OPG expression was first apparent at 24 h after the start of treatment, however it did not reach significant differences.
The data suggest that baicalin may inhibit RANKL mRNA expression via the suppression of COX-2 expression induced by IL-1beta. In addition to its antibacterial and anti-inflammatory properties, baicalin was shown to be effective in periodontitis and alveolar bone resorption.
黄芩苷是从药用植物黄芩中提纯的一种黄酮类化合物。据报道，黄芩苷具有抗菌、抗炎和镇痛作用，且能抑制核因子-κB的激活。牙周病是一种由牙菌斑中的细菌引起的牙周慢性感染性疾病，可导致牙槽骨吸收直至牙齿脱落。人牙周膜（HPDL）是牙槽骨与牙齿之间的结缔组织。核因子-κB受体活化因子配体（RANKL）是肿瘤坏死因子（TNF）配体家族的一员，在破骨细胞前体向成熟破骨细胞的破骨细胞生成过程中起重要作用。在本研究中，我们调查了黄芩苷对白细胞介素-1β（IL-1β）诱导的培养人牙周膜细胞中RANKL蛋白生成及信使核糖核酸（mRNA）表达的影响。
为诱导RANKL表达，将IL-1β加入无血清培养基中的人牙周膜细胞并孵育。向培养基中加入不同浓度的黄芩苷（0、0.001、0.01和0.1微克/毫升），细胞分别处理0、12、24、48和72小时。采用免疫细胞化学法检测细胞中的RANKL。通过半定量逆转录-聚合酶链反应检测RANKL、骨保护素（OPG）和环氧化酶-2（COX-2）的mRNA。
IL-1β刺激人牙周膜细胞中RANKL在mRNA和蛋白水平的表达。黄芩苷在浓度为0.01微克/毫升时抑制IL-1β诱导的RANKL和COX-2生成。黄芩苷处理48小时时观察到最显著的效果。黄芩苷对重组人IL-1β刺激的OPG表达的抑制在处理开始后24小时首次显现，但未达到显著差异。
数据表明黄芩苷可能通过抑制IL-1β诱导的COX-2表达来抑制RANKL mRNA表达。除了其抗菌和抗炎特性外，黄芩苷在牙周炎和牙槽骨吸收方面也显示出有效性。
