A novel flavonoid C-glucoside from Ulmus wallichiana preserves bone mineral density, microarchitecture and biomechanical properties in the presence of glucocorticoid by promoting osteoblast survival: a comparative study with human parathyroid hormone.

PURPOSE: 6-C-ß-D-glucopyranosyl-(2S,3S)-(+)-5,7,3',4'-tetrahydroxydihydroflavonol (GTDF) is a novel compound isolated from Ulmus wallichiana, reported to have bone anabolic action in ovariectomized rats. Here, we studied the effect of GTDF in glucocorticoid (GC)-induced bone loss and its mode of action. METHODS: Osteoblasts were cultured from rat calvaria or bone marrow to study apoptosis and differentiation by dexamethasone (Dex), methylprednisolone (MP), GTDF, quercetin and rutin. Female Sprague Dawley rats were treated with Dex or MP with or without GTDF or PTH. Efficacy was evaluated by bone microarchitecture using microcomputed tomography, determination of new bone formation by fluorescent labeling of bone and osteoblast apoptosis by co-labeling bone sections with Runx-2 and TUNEL. Serum osteocalcin was determined by ELISA. RESULTS: GTDF preserved trabecular and cortical bones in the presence of Dex and MP and mitigated the MP-mediated suppression of serum osteocalcin. Co-administration of GTDF to MP rats increased mineral apposition, bone formation rates, bone biomechanical strength, reduced osteoblast apoptosis and increased osteogenic differentiation of bone marrow stromal cells compared to MP group, suggesting in vivo osteogenic effect of GTDF. These effects of GTDF were to a great extent comparable to PTH. GTDF prevented GC-induced osteoblast apoptosis by inhibiting p53 expression and acetylation, and activation of AKT but did not influence transactivation of GC receptor (GR). CONCLUSIONS: GTDF protects against GC-induced bone loss by promoting osteoblast survival through p53 inhibition and activation of AKT pathways but not as a GR antagonist. GTDF has the potential in the management of GC-induced osteopenia.

Isoformononetin, a methoxydaidzein present in medicinal plants, reverses bone loss in osteopenic rats and exerts bone anabolic action by preventing osteoblast apoptosis.

PURPOSE: Daidzein (Daid) has been implicated in bone health for its estrogen-'like' effects but low bioavailability, unfavorable metabolism and uterine estrogenicity impede its clinical potential. This study was aimed at assessing isoformononetin (Isoformo), a naturally occurring methoxydaidzein, for bone anabolic effect by overcoming the pitfalls associated with Daid. METHODS: Sprague-Dawley ovariectomized (OVx) rats with established osteopenia were administered Isoformo, 17ß-oestradiol (E2) or human parathyroid hormone. Efficacy was evaluated by bone microarchitecture using microcomputed tomography and determination of new bone formation by fluorescent labeling of bone. Osteoblast apoptosis was measured by co-labeling of bone sections with Runx-2 and TUNEL. Biochemical markers of bone metabolism were measured by ELISA. Plasma and bone marrow levels of Isoformo and Daid were determined by LC-MS-MS. Rat bone marrow stromal cells were harvested to study osteoblastic differentiation by Isoformo and Daid. New born rat pups were injected with Isoformo and Daid to study the effect of the compounds on the expression of osteogenic genes in the calvaria by real time PCR. RESULTS: In osteopenic rats, Isoformo treatment restored trabecular microarchitecture, increased new bone formation, increased the serum osteogenic marker (procollagen N-terminal propeptide), decreased resorptive marker (urinary C-terminal teleopeptide of type I collagen) and diminished osteoblast apoptosis in bone. At the most effective osteogenic dose of Isoformo, plasma and bone marrow levels were comprised of ~90% Isoformo and the rest, Daid. Isoformo at the concentration reaching the bone marrow achieved out of its most effective oral dosing induced stromal cell mineralization and osteogenic gene expression in the calvaria of neonatal rats. Isoformo exhibited uterine safety. CONCLUSIONS: Our study demonstrates that Isoformo reverses established osteopenia in adult OVx rats likely via its pro-survival effect on osteoblasts. Given its bone anabolic and anti-catabolic effects accompanied with safety at uterine level we propose its potential in the management of postmenopausal osteoporosis.

Positive skeletal effects of cladrin, a naturally occurring dimethoxydaidzein, in osteopenic rats that were maintained after treatment discontinuation.

UNLABELLED: Effects of cladrin treatment and withdrawal in osteopenic rats were studied. Cladrin improved trabecular microarchitecture, increased lumbar vertebral compressive strength, augmented coupled remodeling, and increased bone osteogenic genes. A significant skeletal gain was maintained 4 weeks after cladrin withdrawal. Findings suggest that cladrin has significant positive skeletal effects. INTRODUCTION: We showed that a standardized extract of Butea monosperma preserved trabecular bone mass in ovariectomized (OVx) rats. Cladrin, the most abundant bioactive compound of the extract, promoted peak bone mass achievement in growing rats by stimulating osteoblast function. Here, we studied the effects of cladrin treatment and withdrawal on the osteopenic bones. METHODS: Adult female Sprague-Dawley rats were OVx and left untreated for 12 weeks to allow for significant estrogen deficiency-induced bone loss, at which point cladrin (1 and 10 mg/kg/day) was administered orally for another 12 weeks. Half of the rats were killed at the end of the treatments and the other half at 4 weeks after treatment withdrawal. Sham-operated rats and OVx rats treated with PTH or 17ß-estradiol (E2) served as various controls. Efficacy was evaluated by bone microarchitecture using microcomputed tomographic analysis and fluorescent labeling of bone. qPCR and western blotting measured mRNA and protein levels in bone and uterus. Specific ELISA was used for measuring levels of serum PINP and urinary CTx. RESULTS: In osteopenic rats, cladrin treatment dose dependently improved trabecular microarchitecture, increased lumbar vertebral compression strength, bone formation rate (BFR), cortical thickness (Cs.Th), serum PINP levels, and expression of osteogenic genes in bones; and reduced expression of bone osteoclastogenic genes and urinary CTx levels. Cladrin had no uterine estrogenicity. Cladrin at 10 mg/kg maintained acquired skeletal gains 4 weeks after withdrawal. CONCLUSION: Cladrin had positive skeletal effects in osteopenic rats that were maintained after treatment withdrawal.