Investigation of inulins from the roots of Morinda officinalis for potential therapeutic application as anti-osteoporosis agent

Scope In China, the root of M . officinalis has been widely used over thousands of years against a wide range of bone disease such as lumbago, limb-ache, sciatica and rheumatic arthralgia, and has tremendous medicinal value. But the bioactive constituents responsible for the osteoprotective effects in M . officinalis remain unknown. Methods and results M . officinalis polysaccharides were extracted, isolated and purified via DEAE-cellulose 52 and Sephacryl S-100HR column to obtain two saccharides (MOP70-1 and MOP70-2). The results of osteogenic activity assays revealed that MOP70-1 and MOP70-2 significantly promoted the proliferation, differentiation and mineralization of MC3T3-E1 cells. Furthermore, MOP70-2 also upregulated gene expression of runt-related transcription factor 2, osterix, osteocalcin, osteopontin, bone sialoprotein and osteoprotegerin, which implied that MOP70-2 stimulated osteoblastic differentiation by up-regulating osteogenic differentiation-related marker genes. In addition, structural analysis indicated that MOP70-2 contained (2 → 1)-linked- β -D-Fru f residues and terminated with a glucose residue. Morphological and conformational analyses indicated that MOP70-2 exhibited spherical structure of conglomeration and had no triple helix structure. Conclusion Our studies reported the osteogenic inulins obtained from root of M . officinalis for the first time. The systematical investigation including extraction, purification, biological activities and structural characterization provide a strong evidence for future therapeutic applications as anti-osteoporosis agent.