The Effects of The 57-kDa Protein Isolated from Korean Royal jelly on the Activity of Human-derived Osteoblast

Abstract

ABSTRACT Royal jelly (RJ) is a secretion product of the cephalic glands of nurse bees that has been used for centuries for its extraordinary properties and health effects. Pharmacological actions of RJ such as antitumor, antiviral, and antioxidant activity have been well noted. RJ and its 57-kDa protein were also reported to enhance the bone-forming ability of osteoblasts and the production of albumin and to have protective effect on rat liver cells. However, the impact of RJ -derived materials, particularly 57-kDa protein, on Saos-2, a human osteoblast-like cell line, is not yet fully understood. Also, no information has been done to consider potential use of RJ -derived materials to manage ultra violet (UV) induced damages. In this study, the effects of RJ and its 57-kDa protein on Saos-2 and the cytoprotective activity of the materials toward Saos-2 cells damaged by UV were evaluated. The cytoprotective activity of the materials was compared with that of N-acetyl-L-cysteine (NAC), a currently used antioxidant, for use as future commercial products with cytoprotective action using a MTS assay. Firstly, 57-kDa protein was purified from domestic RJ using fast protein liquid chromatography and gel filtration method. The 57-kDa protein at concentrations between 10 and 100 μg/mL exhibited a high correlation between protein concentration and cell viability (correlation coefficient (R2) > 0.85). Pretreatment with 0.1 mg/mL 57-kDa protein and 2 mM NAC to Saos-2 cells resulted in 79 and 77% protection against UVB, respectively, whereas 1.5 mg/mL RJ showed no statistically significant protection from radiation induced cell death. Osteoblast extracellular Ca2+-sensing receptor regulates bone development, mineralization, and turnover (Dvorak-Ewell MM et al. 2011). The mitochondria are to generate the cell energy, ATP (i.e., phosphorylation of ADP), and Changes in alkaline phosphatase level and activity are involved in a variety of physiological and pathological events, such as bone development. The effects of 57-kDa protein on the calcium sensing receptor in live cells and mitochondria were compared with cell groups pretreated with UV using confocal microscopy. The microscopic observation revealed that the cells treated with 57-kDa protein showed normal cell shapes and organelles being maintained, similar to normal cells. Pretreatment of Saos-2 cells with 0.1 mg/mL 57-kDa protein significantly resulted in the increase in ALP activity from radiation induced cells. However, 1.5 mg/mL RJ and 2 mM NAC exhibited no statistically significant increase in ALP activity. In conclusion, 57-kDa protein can be useful for the bone formation of osteoblasts and for protection from UV. For practical use of RJ and 57-kDa protein as novel anti- UV induced stress products to proceed, further research is needed to establish their human safety and whether this activity could be exerted in vivo after consumption of the product by humans. In addition, their anti-UV induced stress modes of action need to be established and detailed tests are needed to understand how to improve anti-UV induced stress potency and stability for eventual commercial development.