Structural elucidation and osteogenic activities of two novel heteropolysaccharides obtained from water extraction residues of Cibotium barometz

Cibotium barometz is a tropical and subtropical plant, mainly distributed in the Malaysian Peninsula and southern China. In China, C. barometz has tremendous commercial value in horticultural and medicinal applications. In the present study, alkaline soluble crude polysaccharides (CBBs) were extracted from water extraction residues of C. barometz with sodium hydroxide solution. After deproteinization and dialysis, CBBs were isolated and purified via DEAE-52 cellulose and Sephadex G-75 gel filtration chromatography to obtain two polysaccharide fractions (CBBP-2 and CBBP-3), with relative molecular weights of 10.7 kDa and 1.23 × 10 2  kDa, respectively. Chemical methods and nuclear magnetic resonance (NMR) studies indicated that CBBP-2 was composed of →4)- α - d -Glc p -(1→, →3)- α - l - R ha p -(1→, →3)- α - l -Ara f -(1→, →6)- β - d -Gal p -(1→, →3,6)- α - d -Man p -(1→ and α - d -GalA p -(1→, and CBBP-3 was composed of →6)- β - d -Gal p -(1→, →3)- α - l - R ha p -(1→, →3)- α - l -Fuc p -(1→, →3)- α - l -Ara f -(1→, →3,6)- α - d -Man p -(1→, β - d -GalA p -(1→ and α - d -Gal p -(1→. Morphological and conformational analyses indicated that CBBP-2 had a fragmented and sawdust-like structure. CBBP-3 had a neuron-like morphology, with a number of dendritic branches. Neither CBBP-2 nor CBBP-3 had a triple helix structure. Furthermore, MC3T3-E1 cells were selected to evaluate the osteogenic activities of CBBP-2 and CBBP-3 in an in vitro anti-osteoporosis assay, and the results revealed that CBBP-2 significantly promoted the differentiation of MC3T3-E1 cells at concentrations of 9.4 μM and 18.8 μM and promoted osteogenic mineralization at a low concentration at 4.7 μM. Overall, the systematic extraction, purification, structure identification and bioactivity assays of CBBP-2 and CBBP-3 showed that CBBP-2 could potentially be used as an anti-osteoporotic activity ingredient, with applications in health care and pharmaceutical industries.