Bioactivity-guided fractionation has led to the successful isolation of antiosteoporotic components, i. e., osthole, imperatorin and bergapten from an ethanolic extract of the fruits of Cnidium monnieri (L.) Cusson. Among them, osthole was determined as the major compound possessing antiosteoporotic activity. Further study showed that osthole not only promoted the proliferation and activity of alkaline phosphatase of osteoblasts in neonatal calvaria cultures, but also inhibited the bone resorption by decreasing the formation, differentiation and TRAP activity of osteoclasts derived from rat marrow cells.

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The X-ray structure of bovine ribonuclease A cocrystallized with the dinucleotide deoxycytidylyl-3',5'-guanosine has been determined at 1.9 A resolution and refined by restrained least squares to R = 0.218 for 7807 reflections. The structure established that the recently observed retrobound mode of attachment of substrate analogues cytidylyl-2',5'-guanosine and deoxycytidylyl-3',5'-guanosine found in soaked RNase A crystals is also present in the cocrystallized complex. Retrobinding is thus unlikely to be the result of restrictions imposed by the crystalline environment as the ligands soak into the lattice but rather a phenomenon specific to small nucleotides containing guanine.