The effect of flavone treatment on human otosclerotic ossicle organ cultures

Effect of chronic treatment with ipriflavone in postmenopausal women with low bone mass

We present the results of two multicenter, double-blind, placebo-controlled, 2-year studies to evaluate the efficacy and tolerability of ipriflavone in postmenopausal women (PMW) with low bone mass. 453 PMW (aged 50-65 years) with a vertebral (VMD) or radial (RMD) mineral density value 1 SD lower compared with age-matched controls, were randomly selected to receive oral ipriflavone (200 mg T.I.D. at meals) or matching placebo, plus 1 g oral calcium daily. Vertebral (study A, by dual X-ray absorptiometry-DXA) and radial (study B, by dual photon absorptiometry-DPA) bone density, serum bone Gla-protein (BGP), and urinary hydroxyproline/creatinine (HOP/Cr) were measured every 6 months. In both studies, the Valid Completers (VC) analysis showed a maintenance of bone mass in ipriflavone-treated women, whereas in the placebo group, bone mineral density (BMD) was significantly decreased. The final outcome was a bone-sparing effect of 1.6% in study A, and of 3.5% in study B after 2 years. The Intention to Treat (ITT) analysis confirmed the decrease in the placebo group, with no changes in ipriflavone-treated women. A significant (P < 0.05) between-treatment difference was found in both studies. Biochemical markers of bone turnover decreased in patients treated with ipriflavone, thus suggesting a reduction of bone turnover rate. Twenty-six women treated with ipriflavone and 28 receiving the placebo dropped out because of side effects, mainly gastrointestinal. The compliance to the oral long-term treatment was good. The results of these studies show that ipriflavone is able to prevent both axial and peripheral bone loss in PMW with low bone mass, and is well tolerated.

In vitro and in vivo effects of ipriflavone on bone formation and bone biomechanics

Ipriflavone (i.p.) positively affects bone density in postmenopausal osteoporosis, primarily by inhibiting bone resorption. Using in vitro models of human osteoblast differentiation, we have observed that i.p. and some of its metabolites stimulate the expression of bone sialoprotein, decorin, and type I collagen, and facilitate the deposition of mineralized matrix. This suggests that i.p. may stimulate bone formation in addition to its antiresorptive activity. To assess whether these effects translate into an improved bone "quality" in vivo, we measured biomechanical properties, mineral composition, and crystallinity of femurs of 12-week-old, male, Sprague-Dawley rats treated with i.p. for 1 month. i.p. significantly decreased vibration damping, an index of strain energy loss. Because vibration damping increases as bone porosity increases, the results indicate that i.p.-treated bones acquired a higher capacity to withstand dynamic stress. In fact, 1.5-fold higher energy was required to fracture femurs of i.p.-treated rats after a single supramaximal impact. i.p. also increased BMD, assessed by both volume displacement and ash analysis, whereas the relative contents of Ca, P, and Mg in the ashes were not affected. Thus, no gross abnormalities in mineral composition of bone occurred after i.p. administration. As a measure of bone crystallinity, X-ray diffraction analysis was performed. The broadening parameter beta 1/2 for the (310) and (002) reflections was not significantly different between i.p.-treated and control animals. Similarly, there were no differences in serum levels of Ca, Mg, alkaline phosphatase, and type I collagen telopeptides between treated and control animals at the end of the study. Therefore, 1-month treatment with i.p. increased bone density and improved the biomechanical properties of adult male rat bones without altering mineral composition or bone crystallinity.

Effects of ipriflavone and its metabolites on human articular chondrocytes cultivated in clusters

Ipriflavone (IP) is an isoflavone derivative that was suggested to have bone-sparing effects in post-menopausal and senile osteoporosis. A moderate stimulatory effect of IP and its metabolites on proliferation of osteoblastic cells was reported in rat osteoblastic osteosarcoma cell line. We investigated the effects of different concentrations (0, 1, 10 and 100 micrograms/ml) of IP and its metabolites (MET I, II, III and V) on the incorporation of [3H] thymidine and production of proteoglycans (PG) and type II collagen (COL II) by human articular chondrocytes during a 12-day period, in a three-dimensional chondrocyte culture model. [3H]thymidine uptake was measured in chondrocyte clusters, and specific PG and COL II radioimmunoassays were performed every 4 days on the culture medium and cell clusters. Incubation with IP or its metabolites did not affect [3H]thymidine uptake regardless of the dose. PG released into the culture medium and PG cluster content rose significantly (P < 0.025) in presence of IP (1, 10 and 100 micrograms/ml). MET I increased PG release in culture medium (10 and 100 micrograms/ml) and PG cluster content (100 micrograms/ml). MET II has no effect on PG production. MET III increased PG in culture medium (100 microgram/ml) but did not influence PG cluster content while MET V (100 micrograms/ml) increased both PG release in culture medium and PG cluster content. COL II release in culture medium and COL II cluster content were significantly (P < 0.025) increased in presence of IP (10 and 100 micrograms/ml), MET III (1, 10 and 100 micrograms/ml) or MET V (100 micrograms/ml). MET I and II did not significantly affect COL II production.

Ipriflavone improves bone density and biomechanical properties of adult male rat bones

To assess the potential impact of ipriflavone on the biomechanical properties and mineral composition of bone, we administered two doses (200 or 400 mg/kg bw) of the drug orally to adult male rats for 1 month. Bone biomechanics were evaluated by vibration damping, an index of strain energy loss, and impact strength (the amount of energy required to fracture after a single impact). At the higher dose, ipriflavone significantly decreased vibration damping of rat femurs by 23.0 +/- 9.8% compared with control, vehicle-treated animals, suggesting a higher capacity to withstand dynamic stress. This result was confirmed by the impact strength studies showing that a higher energy (49.6 +/- 21.3% above control) was required to fracture femurs of rat treated with 400 mg/kg bw ipriflavone. The high dose of ipriflavone increased bone mineral density, assessed by both volume displacement and ash analysis (4.2% and 2.5% above controls, respectively). The relative content of calcium, phosphorus, and magnesium in the ashes was not different among the treated and untreated groups, indicating that no gross abnormalities in mineral composition of bone occurred after ipriflavone administration. Similarly, there were no differences in serum calcium and magnesium levels between treated and control animals at the end of the study, whereas lower circulating phosphorus levels were detected in the latter. Ipriflavone treatment was not associated with significant changes in serum alkaline phosphatase nor type I collagen telopeptide levels, two markers of bone turnover. In summary, 1-month treatment with ipriflavone increased bone density and improved the biomechanical properties of adult rat male bones without altering mineral composition.(ABSTRACT TRUNCATED AT 250 WORDS)

Flavonoids alter bone-remodelling in auditory ossicle organ cultures

The beneficial role of bioflavonoids in an otosclerosis-like bone-remodelling process can be implicated from its interference with bone resorption induced by prostaglandin E2 (PGE2) in cultured guinea pig ossicles. Ipriflavone (7-isopropoxy-isoflavon) and quercetin reduced PGE2-elevated collagenase-like peptidase (Cl-peptidase) activity and potentiated a PGE2-induced decrease in collagen synthesis. The fact that PGE2 effects are mediated through cyclic AMP in bone turnover and flavonoids act synergistically with PGE2 in collagen synthesis confirm a cyclic AMP phosphodiesterase inhibitory role of flavonoids. It has already been attempted to use Ipriflavone medical treatment of otosclerosis. Quercetin, which has a better than Ipriflavone water-solubility seems as promising as Ipriflavone in the control of the otosclerotic bone-remodelling disturbance.

Metabolic and bone effects after administration of ipriflavone and salmon calcitonin in postmenopausal osteoporosis

Forty postmenopausal women with bone mineral density (BMD) > 2 standard deviations below the mean value for healthy age matched controls were enrolled into an open controlled study to evaluate the metabolic and bone effects of ipriflavone (IP) versus salmon calcitonin (sCT) over a 12 month period. Both treatments significantly increased BMD after 6 and 12 months. A 4.3% increase of BMD was obtained in the IP treated group and a 1.9% in the sCT treated group after 12 months (p < 0.001 between treatments). Bone metabolism markers (serum osteocalcin, alkaline phosphatase, urinary calcium and hydroxyproline/creatinine ratio) were significantly reduced in both groups (p < 0.001). The reduction of urinary hydroxyproline/creatinine ratio was significantly greater (p < 0.05) in the IP group after 12 months. Both treatments were well tolerated. Four patients in the IP group reported gastralgia while two patients in the sCT group reported pruritus and one patient epistaxis.

Ipriflavone-treatment of senile osteoporosis: results of a multicenter, double-blind clinical trial of 2 years

Eighty-four out of 100 enrolled female patients affected by osteoporosis completed a double-blind, randomized trial, using ipriflavone (IP) in a dose of 3 x 200 mg/day (41 patients) or placebo (P)(43 patients). All patients received 1 g/day oral calcium supplementation. Inclusion criteria were: age over 65 years; at least one vertebral fracture in the past; bone mineral density measured at the distal tenth of the radius lower than the normal average -2 x S.D. The trial period was between June 1990 and November 1993. Patients of the IP group showed a significant increase in bone mineral density (P < 0.05) compared with the starting values during the whole study period. Pain decreased rapidly, intake of analgesics dropped, and often significant decreases in calciuria, hydroxyprolinuria, alkaline phospatase, osteocalcin and parathormone values were observed. Only two new fractures occurred during the trial in the IP group. Patients of the P group at the end of the study displayed decreased bone mineral densities (P < 0.05), increased pain, greater consumption of analgesics, and often significant increases in the bone metabolism parameters listed for the IP group. In the

Stimulation of human osteoblast differentiation and function by ipriflavone and its metabolites

Ipriflavone (IP), an isoflavone derivative, has been shown to interfere with bone remodeling by inhibiting bone resorption and perhaps stimulating bone formation. In this study, we have analyzed the effect of IP and its metabolites on the differentiation and function of human osteoblastic cells. Bone marrow stromal osteoprogenitor cells (BMC) and trabecular bone osteoblasts (HOB) were isolated from human donors. The former can be induced to differentiate by treatment with dexamethasone, whereas the latter represent a more differentiated osteoblast. Incubation of BMC with metabolite III (10(-5) M) for 1 week induced modest but significant changes of alkaline phosphatase activity. Though both IP and metabolite III stimulated the expression of bone sialoprotein mRNA, a protein involved in cell attachment to the matrix, only metabolite III increased the steady-state level of decorin mRNA, a collagen fibrillogenesis-regulating proteoglycan. Metabolites III and V, but not the other isoflavones, increased the expression of type I collagen mRNA in HOB, whereas no detectable changes were observed in BMC cells with any of the experimental compounds. In HOB, an increased abundance of osteopontin and bone sialoprotein mRNA were also obtained after 1-week treatment with IP or metabolite V. No appreciable effects of IP or its metabolites were seen on osteocalcin expression and synthesis by either cell type. Finally, IP consistently increased the amount of 45Ca incorporated into the cell layer by BMC, and stimulated mineralization of both BMC and HOB, assessed by von Kossa staining. Thus, IP and its metabolites regulate the differentiation and biosynthetic properties of human bone-forming cells by enhancing the expression of some important matrix proteins and facilitating the mineralization process.

New perspectives in the treatment of postmenopausal osteoporosis: ipriflavone

The efficacy and safety of ipriflavone, a new anti-osteoporotic agent, has been evaluated in an open study in 100 agent, has been evaluated in an open study in 100 osteoporotic women. Ipriflavone was administered as oral capsules dosed at 200 mg, 3 times a day for 12 months. Ninety women completed the study, and the results indicate that the bone mineral density was increased by 2% and 5.8% after 6 and 12 months, respectively. Pain and rachis mobility seemed to be positively influenced by ipriflavone. Only three women complained of side-effects (gastralgia and nausea) and asked to stop the therapy.

Alternatives to HRT in prevention and treatment

Oestrogen hormone replacement therapy remains the first choice for the treatment and prevention of osteoporosis in postmenopausal women, but for patients who are unsuitable for this therapy, which of course includes men, other satisfactory treatments are available. Several placebo-controlled studies have demonstrated that bisphosphonates and calcitonin prevent bone loss or perhaps increase bone density over 2-3-year periods, and reduce the rate of fracture. It is not known whether these treatments will increase bone density over longer periods of time. Cyclical etidronate has recently become licensed in the UK for use in the treatment of osteoporosis, and it is hoped that other bisphosphonates and intranasal calcitonin will soon be added to the available treatments. Fluoride appears to increase bone density but, at doses above a very narrow therapeutic window, it increases the fracture rate, either because of bone redistribution, formation of poor quality bone or a toxic effect on osteoblasts. At present, fluoride remains a treatment to be used only under expert supervision or within the context of controlled clinical trials. Anabolic steroids may be of value in selected elderly patients with osteoporosis. The patient may be able to contribute to the prevention of osteoporotic fracture by exercising, which will improve dexterity and may have a small effect to increase bone density, and by avoiding the factors that predispose to falls, such as icy paths and excess alcohol. Changes in the diet are unlikely to play a major role in the maintenance of bone density in women living in the Western world.

Effect of ipriflavone on bone mass in elderly osteoporotic women

A study in elderly osteoporotic women was performed to assess the effect of one year treatment with ipriflavone (IP) on bone mass and bone biomarkers. Twenty-eight women aged over 65, with diagnosis of osteoporosis and X-ray evidence of at least one vertebral fracture, were treated with IP tablets (600 mg/day) or placebo (PL), according to a randomized, double-blind, parallel-group design. One g/day calcium supplementation was given to all patients. After 12 months a significant increase (+6%, P < 0.05) of bone mineral density (BMD) at the distal radius (DPA) was obtained in the IP-group. Serum osteocalcin (BGP) and urinary HO-proline/creatinine (HOP/Cr) values were reduced in the same group. BMD values did not change (-0.3%) in the placebo group. One woman of the PL-group was withdrawn from treatment because of worsening of pain, due to new vertebral crushes. Side effects (mainly gastrointestinal) arose in 8 IP- and in 5 PL-treated women. The compliance to the oral administration was good.

Ipriflavone inhibits phosphoinositide hydrolysis and Ca2+ uptake in the osteoblast-like UMR-106 cells

The mechanism of action of ipriflavone, an isoflavone derivative, was studied in the osteoblastic-like UMR-106 cell line. Ipriflavone affected both phosphoinositide hydrolysis and 45Ca2+ uptake. A repeated treatment of UMR-106 cells (once a day, for 3 days) with ipriflavone decreased, in a concentration-dependent manner, [3H]inositol monophosphate accumulation. This effect was also achieved after single addition of high concentrations of ipriflavone or 100 nM [Asu1,7]eel-calcitonin, a semi-synthetic analog of eel calcitonin. When repeatedly added to UMR-106 cells, 17 beta-estradiol produced a marked inhibition of [3H]inositol monophosphate accumulation, an effect which appeared significant only at a concentration of 1 microM and which was accompanied by a reduced incorporation of [3H]inositol into membrane phospholipids. A repeated treatment with ipriflavone reduced 45Ca2+ uptake as well. This effect was observed also after a single addition of [Asu1,7]eel-calcitonin but not following single or repeated treatment with 17 beta-estradiol. The present data indicate the osteoblast as a direct and specific target for ipriflavone and suggest that this compound may share intracellular transducing mechanisms with other antiosteoporotic hormones such as estrogen and calcitonin.

Histochemical and fine structural study of bone of ipriflavone-treated rats

Bone labeling, histochemical, and fine structural studies were performed in order to clarify the effects of ipriflavone (IP) on rat bone tissue in vivo and in vitro. Labeling experiments showed a slight increase in bone formation during 3 days' administration. It was also noted that many osteoclasts detached from the bone surface at 1, 2, and 6 hours after administration in vivo. In addition, irregular localization of tartrate-resistant acid phosphatase (TRACPase) activity was observed in osteoclasts. Fine structurally, IP-treated osteoclasts exhibited irregularity in their ruffled borders, as reported in calcitonin administration, and many enlarged rough endoplasmic reticuli and vacuoles were observed. However, osteoclasts at 12 hours after administration, as well as the control, indicated recovery features from the effect of IP. Osteoblast proliferation and differentiation led to increasing alkaline phosphatase activity (ALPase) with time as well as the development of rough endoplasmic reticuli and Golgi apparatus with well-developed fine structure. These findings imply active synthesis of bone matrix. In our in vitro experiment, osteoclasts and osteoblasts displayed histochemical and fine structural characteristics similar to those observed in our in vivo experiment. Moreover, fewer TRACP-positive mononuclear cells were observed after 24-hour culture with IP than with the control. These results suggest that IP inhibits directly and/or indirectly differentiation and activity of osteoclasts and also promotes differentiation of osteoblast-lineage cells and their bone-forming activity.

Effects of ipriflavone and its metabolites on a clonal osteoblastic cell line

Protective effects of ipriflavone, an isoflavone derivative, in osteoporosis are believed to be caused by the inhibitory action on bone resorption. A direct effect of ipriflavone on bone formation is as yet unknown. Ipriflavone and four of its metabolites (I, II, III, and V) were examined for their effects on parathyroid hormone response, collagen synthesis, alkaline phosphatase activity, and cell proliferation in a clonal cell population of rat osteoblastic cells. Pretreatment of osteoblasts with high concentrations of ipriflavone for 48 h significantly inhibited the cAMP response to parathyroid hormone, producing a shift in the dose-response curve; at lower concentrations metabolites II and III potentiated the cAMP accumulation induced by low doses of parathyroid hormone. The 48 h treatment with metabolite V at the 1 nM dose significantly stimulated collagen synthesis in osteoblastic cells. Ipriflavone and metabolite I showed a biphasic stimulatory action on the alkaline phosphatase activity of osteoblasts, with a maximal effect at the 0.1 and 1 nM doses, respectively. A similar biphasic response was observed with ipriflavone and metabolite I on osteoblastic cell growth, with a maximal effect at the 0.1 nM concentration. These results suggest a direct role of ipriflavone in modulating the synthetic and growth properties of osteoblast-like cells.