Structural characterization and osteoprotective effects of a novel oligo-glucomannan obtained from the rhizome of Cibotium barometz by alkali extraction

Cibotium barometz is mainly distributed in eastern, southern, and southwest China as an important industrial export crop of great economical and medicinal value. The rhizome of C. barometz is widely used in Traditional Chinese Medicine clinics to treat conditions such as lumbago, limb-ache, rheumatism, and sciatica. In this study, the results of in vivo pharmacological experiments conclusively demonstrated that crude saccharides from C. barometz (CBB) exhibited osteoprotective effects in ovariectomized rats, which significantly increased bone mineral content (BMC) and bone mineral density (BMD), and prevented damage of the trabecular bone, consequently improving its biomechanical properties. To investigate the biological active ingredient(s), a novel oligo-glucomannan (denoted CBBP-1) was isolated and purified from CBB via anion-exchange and size-exclusion chromatography. Structural analysis indicated that CBBP-1 consisted of (1 -> 4)-linked a-D-glucose, (1 -> 6) linked beta-D-glucose with (1 -> 3, 6)-linked a-D-mannose, and a terminal alpha-D-glucose. Morphological analysis revealed that CBBP-1 had an irregular sheet structure. Furthermore, osteoblastic MC3T3-E1 cells treated with CBBP-1 had significantly increased mRNA expression of runt-related transcription factor 2, osterix, osteopontin, osteocalcin, and bone sialoprotein, indicating that CBBP-1 may stimulate osteoblastic differentiation. In conclusion, this study provides evidence that CBBP-1 may have potential as an anti-osteoporosis agent in the pharmaceutical industry.