Structural elucidation and anti-osteoporosis activities of polysaccharides obtained from Curculigo orchioides

Curculigo orchioides, is a traditional Chinese medicine, is used in strengthening tendons and bones. We evaluated the anti-osteoporosis activity of the crude polysaccharide (CO70) isolated from the rhizomes of C. orchioides in ovariectomized rats. CO70 showed excellent anti-osteoporosis activity comparable to that of 17 beta-estradiol. To explore the constituents responsible for the anti-osteoporosis activity of CO70, a novel homogeneous heteropolysaccharide, COP70-3, was isolated and purified from CO70. COP70-3 has a main backbone chain of (1.5)linked alpha-L-Araf, (1,3 -> 5)-linked alpha-L-Araf, (1 -> 6)-linked beta-D-Galp, (1 -> 4)-linked beta-D-Manp, (1,2 -> 5)-linked alpha-L-Araf, (1 -> 3)-linked beta-L-Rhap, (1,3 -> 6)-linked beta-D-Manp, (1 -> 3)-linked alpha-D-GalpA, (1,3 -> 6)-linked beta-D-Galp and (1 -> 6)-linked alpha-D-Glcp residues. Furthermore, 1.87 nM COP70-3 obviously promoted the differentiation of MC3T3-E1 cells, while 0.94 and 1.87 nM COP70-3 significantly improved the osteogenic mineralization rate. These data indicate that COP70-3 has favorable anti-osteoporosis activity in vitro.