Beneficial regulation of vitamin D 3 -rich extract from the processing by-products of Penaeus sinensis on preosteoblastic MC3T3-E1 cells and improvement of bone health in VD-deficient mice.

Vitamin D (VD) plays an important role in preventing osteoporosis. However, knowledge of the osteogenic effect of VD from shrimp processing by-products is limited. In this study, a VD-rich extract from Penaeus sinensis processing by-products was prepared by saponification and liquid-liquid extraction combined with solid phase extraction for purification. The activity of purified VD-rich extract (PPs-VD) on MC3T3-E1, a preosteoblastic cell line, was determined. Furthermore, the improvement effect of PPs-VD on bone health of VD-deficient mice was investigated. PPs-VD stimulated the proliferation and differentiation of MC3T3-E1 cells. Compared to the same concentration of the VD standard, mineralization of MC3T3-E1 cells increased after 14 d or 21 d of PPs-VD treatment. Western blotting showed that PPs-VD significantly upregulated the protein levels of bone morphogenetic protein 2 and runt-related transcription factor 2 compared to the VD standard. Furthermore, PPs-VD treatment activated the receptor activator of nuclear factor-kappa B ligand (RANKL)/osteoprotegerin (OPG) signaling pathway in MC3T3-E1 cells, especially increased OPG expression was detected at day 3 to day 14 compared to the VD standard treatment. More than ten medium and long chain fatty acids were detected in PPs-VD, of which n-3 polyunsaturated fatty acids (PUFA) constituted 38.83 ± 8.61%, and the n-3/n-6 PUFA ratio in PPs-VD3 was 2.84 ± 0.23. The femoral trabeculae number and thickness of VD-deficient mice increased after 3 weeks of PPs-VD treatment. The changes of parameters associated with bone resorption including parathyroid hormone, bone mineral density and tartrate resistant acid phosphatase revealed the contribution of PPs-VD treatment in improving bone remodeling in VD-deficient mice. Our results suggest that PPs-VD could have potential prospects in alleviating osteoporosis or promotion of bone health.