Effects of icariin on the alkline phosphatase activity of human periodontal ligament cells inhibited by lipopolysaccharide.

Icariin (ICA), a flavanoid isolated from herbal Epimedium, has multiple biological activities. The present study investigated the effects of ICA on the proliferation and alkaline phosphatase (ALP) activity (an index for PDLC differentiation) of human periodontal ligament cells (hPDLCs) inhibited by lipopolysaccharide (LPS). hPDLCs were cultured in vitro and stimulated with various concentrations of ICA. The proliferation ability of hPDLCs was detected by an MTT assay. The activity of ALP was determined by the p-Nitrophenyl phosphate method, and the expression of ALP was analyzed by reverse transcription polymerase chain reaction and western blot analysis. ICA exhibited a dose-dependent effect on the proliferation of hPDLCs in a suitable concentration range, from 10-6 to 10-8 mol/l, and with a mediate optimal concentration (10-6 mol/l). The alkaline phosphatase activity was markedly inhibited in 10 µg/ml LPS-treated PDLCs and this inhibition was suppressed in the presence of icariin at a concentration of 10-6 mol/L following prolonged treatment (96 h). Therefore, this study provided insight into the use of ICA for periapical tissue regeneration.