In vitro antimicrobial effect of curcumin-based photodynamic therapy on Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans.

BACKGROUND: Photodynamic therapy (PDT) is a bactericidal method, which has recently been introduced in the field of dental medicine and therapy. Curcumin, a compound isolated from Curcuma longa L., exerts potent phototoxic effects at micromolar concentrations. The aim of our study was to explore the in vitro antimicrobial effect of curcumin-based PDT on two major etiological agents of periodontitis, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans. METHODS: P. gingivalis ATCC33277 and A. actinomycetemcomitans ATCC24523 suspension was irradiated with blue LED (BL) (450-470 nm, output power density 1.2 W/cm2) for 20-60 s (6-18 J/cm2), treated with curcumin (2 min), or subjected to a combination of curcumin treatment and BL irradiation (60 s, 18 J/cm2). A suspension of chlorhexidine gluconate (CHG) was used as the positive control. All bacterial suspensions used were serially diluted, plated, and incubated anaerobically or microaerobically. The numbers of colony-forming units (CFUs) were counted on day 7. One-way analysis of variance (ANOVA) and Tukey's HSD tests were used for statistical analysis. RESULTS: BL irradiation at 6, 12, and 18 J/cm2 alone reduced the number of CFUs of both P. gingivalis and A. actinomycetemcomitans, but the reduction was not statistically significant. Compared with BL irradiation alone, curcumin solution at 20 µmol/L used alone achieved a lower reduction in the number of CFUs. Combined use of BL at 18 J/cm2 20 µmol/L curcumin treatment yielded a log reduction of 0.43 and 1.51 for P. gingivalis and A. actinomycetemcomitans CFUs, respectively. Suspensions treated with 0.12 % CHG showed a log reduction of 0.29 and 0.28 for P. gingivalis and A. actinomycetemcomitans CFUs, respectively. CONCLUSIONS: Although the bactericidal and growth-inhibitory effects of BL alone on P. gingivalis and A. actinomycetemcomitans were not significant, A. actinomycetemcomitans was susceptible to photodynamic inactivation by the combination of BL and curcumin.

Response of human periodontal ligament cells to baicalin.

BACKGROUND: Periodontitis is the most common cause of tooth loss in adults. Periodontal ligament cell (PLC)-based therapy is considered one of the most promising methods in periodontal tissue regeneration. The traditional Chinese medicine baicalin has been shown to possess antimicrobial and anti-inflammatory activities and enhance cell proliferation and alkaline phosphatase activity. The aim of this study is to investigate the response of human PLCs (HPLCs) to baicalin. METHODS: The effect of baicalin on cultured HPLC proliferation was measured with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The effect of baicalin on the expression of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL), core binding factor α1 (Cbfα1), and osteocalcin (OC) was determined by quantitative real-time polymerase chain reaction and immunodetection. RESULTS: Baicalin at a concentration of 0.01 µg/mL promoted HPLC proliferation, upregulated OPG messenger RNA (mRNA) and protein expression, and downregulated RANKL mRNA and protein expression. In addition to reducing the RANKL/OPG expression ratio significantly, it also increased Cbfα1 and OC mRNA and protein expression. CONCLUSION: Baicalin showed multifaceted regulation of genes with important roles in tissue growth and differentiation, and thus it has the potential to be a promising candidate for HPLC-based periodontal regeneration therapy.

[Effect of icariin on osteoblastic differentiation gene expression of human periodontal ligament cells].

OBJECTIVE: To observe the effect of icariin on human periodontal ligament cells (hPDLCs) differentiation to osteoblast gene expression. METHODS: The fifth generation of the cultured hPDLCs was added with the concentration of 0.01 mg/L icariin, and the added osteogenic medium used as blank control group, alizarin red staining of icariin on human periodontal ligament cells was observed for 21 days; the 2, 4, and 6 days of Q-PCR quantitative analysis of icariin on human periodontal ligament cells were made for osteogenesis gene alkaline phosphatase (ALP), type I collagen and osteocalcin (OC) gene expression. RESULTS: For the 21 days, alizarin red staining icariin group formed more mineralized nodules; on the 2nd, 4th, and 6th days, the group of icariin promoted the expression of ALP and OC mRNA, reached the peak value on day 6, compared with the control group with significant difference (20.15±6.67 vs. 7.90±0.71, 4.13±0.56 vs. 3.55±0.08, P<0.01). The second day, the highest expression of type I collagen appeared, then decreased gradually after, statistically compared with the control group (P<0.05). CONCLUSION: Icariin can promote the human periodontal ligament cells differentiation to osteoblast, and promote the osteogenesis gene expression.

Effect of icariin on cell proliferation and the expression of bone resorption/formation-related markers in human periodontal ligament cells.

Periodontitis is a common destructive inflammatory disease that leads to changes in the tooth-supporting tissues. Human periodontal ligament cells are essential in periodontal tissue regeneration. The traditional Chinese medicine icariin promoted bone formation, stimulated the osteogenic differentiation of preosteoblastic cells and inhibited osteoclast differentiation and bone resorption. Thus, in the present study, the effect of icariin on cell proliferation and the expression of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL), core binding factor α1 (Cbfa1) and osteocalcin (OC) was investigated in human periodontal ligament cells, by an MTT assay, qPCR and western blot analysis. The results demonstrated that icariin promoted cell proliferation in a dose- and time-dependent manner, upregulated OPG, Cbfa1 and OC expression, and downregulated RANKL production and the RANKL/OPG expression ratio. This suggested the potential value of icariin in treating alveolar bone resorption and promoting periodontal tissue regeneration, due to its ability to stimulate the proliferation and osteogenic differentiation of human periodontal ligament cells and inhibit osteoclast differentiation.