Cellular properties of the fermented microalgae pavlova lutheri and its isolated active peptide in osteoblastic differentiation of MG-63 cells

Fermented microalgae Pavlova lutheri (P. lutheri), the product of Hansenula polymorpha fermentation, exhibited an increase in alkaline phosphatase (ALP) activity in MG-63 osteoblastic cells when compared to that of non-fermented P. lutheri. Fractionation of the fermented P. lutheri resulted in identification of the active peptide [peptide of P. lutheri fermentation (PPLF)] with the sequence of EPQWFL. PPLF significantly increased ALP release from MG-63 cells and mineralization in a dose-dependent manner. In addition, the intracellular levels of ALP and osteocalcin (OCN) proteins were augmented by PPLF treatment. To identify the molecular mechanism underlying the effect of PPLF on osteoblastic differentiation, the phosphorylation levels of the mitogen-activated protein kinases, p38, extracellular signal-regulated kinases 1/2 and Jun, and nuclear factor (NF)-κB were determined following PPLF treatment and the differences in expression were analyzed using p38 and NF-κB selective inhibitors. These results concluded that PPLF from fermented P. lutheri induced osteoblastic differentiation by increasing ALP and OCN release in MG-63 cells via the p38/p65 signaling pathway, indicating that PPLF supplement may be effective for therapeutic application in the field of bone health.