Dietary quercetin inhibits bone loss without effect on the uterus in ovariectomized mice.

Quercetin is a major dietary flavonoid found in onions and other vegetables, and potentially has beneficial effects on disease prevention. In the present study, we demonstrate for the first time the effects of dietary quercetin on bone loss and uterine weight loss by ovariectomy in vivo. Female mice were ovariectomized (OVX) and were randomly allocated to 3 groups: a control diet or a diet with 0.25% (LQ) or 2.5% quercetin (HQ). After 4 weeks, dietary quercetin had no effects on uterine weight in OVX mice, but bone mineral density of the lumbar spine L4 and femur measured by peripheral quantitative computed tomography (pQCT) was higher in both the sham and the HQ groups than in the OVX group. Histomorphometric analysis showed that the HQ group restored bone volume (BV/TV) completely in distal femoral cancellous bone, but did not reduce the osteoclast surface area and osteoclast number when compared with the OVX group. In in-vitro experiments using mouse monocyte/macrophage cell line RAW264.7 cells, however, quercetin and its conjugate, quercetin-3-O-beta-D: -glucuronide dose-dependently inhibited the receptor activator of nuclear factor-kappa B ligand (RANKL)-induced osteoclast differentiation, and the RANKL-stimulated expression of osteoclast related genes was also inhibited by quercetin. The luciferase reporter assay showed that quercetin did not appear to have estrogenic activity through estrogen receptors. These results suggest that dietary quercetin inhibits bone loss without effect on the uterus in OVX mice and does not act as a potent inhibitor of osteoclastogenesis or as a selective estrogen receptor modulator in vivo.

Water extract of Cordyceps sinensis (WECS) inhibits the RANKL-induced osteoclast differentiation.

It has been reported that Cordyceps sinensis, a traditional Chinese medicine, has various pharmacological effects. The aim of this study was to clarify the effect of water extract of Cordyceps sinensis (WECS) on osteoclast differentiation in vitro. In mouse bone marrow cells and monocyte/macrophage cell line RAW264.7, WECS dose-dependently inhibited the receptor activator of nuclear factor kappa B (NF-kappaB) ligand (RANKL)-induced osteoclast differentiation by tartrate-resistant acid phosphatase (TRAP) staining. In fact, cytotoxic effect was not observed in the RAW264.7 cells treated with WECS. Moreover, the mRNA expression of osteoclast related genes (calcitonin receptor, cathepsin K, matrix metalloprotease 9 and nuclear factor of activated T cells c1) was also inhibited by WECS. Investigation of inhibitory mechanism by using electrophoretic mobility shift assay (EMSA) and Western blot analysis revealed that WECS inhibited the activation of NF-kappaB through the prevention of IkappaBalpha phosphorylation. In conclusion, the present results demonstrate for the first time that WECS is a potent inhibitor of the RANKL-induced osteoclast differentiation through a mechanism involving the NF-kappaB pathway.

Peptic digestibility of raw and heat-coagulated hen's egg white proteins at acidic pH range.

Allergenicity in food proteins is generally dependent on their heat stability and resistance to digestive enzymes together with the presence of IgE-recognizing epitopes on the molecules. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting, we assessed peptic digestibility of raw and heat-coagulated hen's egg white proteins at acidic pH range (1.5-4.0). Ovalbumin in raw egg white was slightly digested by pepsin at pH 1.5 and pH 2.0, and was almost resistant to the enzyme at pH 2.5 and over, which was altered in heat-coagulated egg white at the pH range from 1.5 to 2.5 where the protein was well digestive against the enzyme. Peptic digestibility of ovomucoid in raw egg white was good at the pH range from 1.5 to 2.5, but almost non-existent at pH 3.0 and over where the improvement of the digestibility of the protein was not found even in heat-coagulated egg white. As the stomach in new born infants shows a low amount of secretary pepsin and an out of optimum pH of peptic activity, low digestibility of ovalbumin and ovomucoid in raw and heat-coagulated egg white at over pH 3.0 is supposed to be responsible for their allergenicity and delayed outgrowth from hen's egg allergy in patients with delayed maturation of stomach functions.