A review: the mechanism of plant-derived polysaccharides on osteoblasts and osteoclasts

Bone loss and deterioration of bone microarchitecture would increase the bone fragility and fracture risk, leading to the osteoporosis. More and more evidences proved that plant-derived polysaccharides could have a remarkable influence on osteoblasts and osteoclasts, exerting anti-osteoporosis effects. According to the previous research, the extract of Cibotium barumoz, Achyranthes bidentata, Curculigo orchioides, Epimedium brevicornum, Angelica sinensis, Polygonatum sibiricum, Dendrobium officinale, Morinda officinalis, Nelumbo nucifera, Diospyros kaki, Hordeum vulgare, Cistanche deserticola, Commiphora Myrrha and other plant-derived polysaccharides could benefit to the osteoblasts and osteoclasts. The essential mechanisms are mainly related to the activation or inhibition of many factors, including runt-related transcription factor 2 (Runx2), β-catenin, osterix (Osx), activator protein-1 (AP-1), osteocalcin (OCN/BGP), alkaline phosphatase (ALP), osteopontin (OPN), bone morphogenetic protein (BMP), phosphatidylinositol 3-kinase (PI3K)/C-Jun N-terminal kinase (JNK)/extracellular regulated protein kinase (ERK), osteoprotegerin (OPG), receptor activator of nuclear factor-κB (RANK), monocyte/macrophage colony-stimulating factor (M-CSF), tumor necrosis factor receptor-associated factor 6 (TRAF-6), receptor activator of nuclear factor (NF)-κB ligand (RANKL), nuclear factor of activated T cells 1 (NFATc1), c-Fos, matrix metallopeptidase-9 (MMP-9), glycogen synthase kinase 3β (GSK3β)/β-catenin, nuclear factor E2-related factor 2 (Nrf2), as well as these related pathways, such as Wnt/β-catenin, BMP-2/SMAD1/5/8, PI3K/AKT, OPG/RANKL/RANK, NF-κB, MAPKs, etc. These plant-derived polysaccharides could improve the dynamic balance of bone formation and resorption through promoting the differentiation and maturation of osteoblast or inhibiting its formation. The reviewed plant-derived polysaccharides and their regulating mechanisms on the osteoclasts and osteoblasts provide the evidences for the development of osteoporosis therapeutics.