Effect of Polyphenols on Calcium Content and Alkaline Phosphatase Activity in Rat Femoral Tissues in Vitro.

Abstract

This loss may be due to increased bone resorption and decreased bone formation. Osteoporosis with a decrease in bone mass is widely recognized as a major public health problem.4) The most dramatic expression of this disease is represented by fractures of the proximal femur. Pharmacological and nutritional factors may prevent bone loss with increasing age. 5,6) The chemical compounds in food that act on bone metabolism, however, are poorly understood.Genistein is a natural isoflavonoid phytoestrogen found in Leguminosae. The isoflavonoid has been shown to have a strong inhibitory effect on protein tyrosine kinase, 7,8) and it can produce cell cycle arrest and apoptosis in leukemic cells. 8,9) The biological effect of genistein, however, has not been fully clarified. Recently, genistein has been demonstrated to have an anabolic effect on bone metabolism, suggesting its role in the prevention of osteoporosis. [10][11][12][13][14] Genistein has a stimulatory effect on bone formation and mineralization in tissue culture systems in vitro, [15][16][17] and it can stimulate protein synthesis in osteoblastic cells. [18][19][20] Moreover, genistein has been shown to inhibit osteoclastic bone resorption by preventing the formation and differentiation of osteoclast-like cells from bone marrow cells, 21,22) and the apoptosis of mature osteoclasts is induced by genistein through the Ca 2ϩ signaling mechanism. 23,24) Thus genistein may be of significance in the prevention of bone loss with increasing age.The effect of various polyphenols found in food and plants on bone metabolism, however, has not yet been clarified. The present study was undertaken to determine the effect of polyphenols (glycitein, resveratrol, quercetin, catechin, and (Ϫ)-epigallocatechin gallate (EGCg) on bone calcification in vitro. Of various polyphenols used, genistein was found to have a unique anabolic effect on bone calcification. MATERIALS AND METHODSChemicals Dulbecco's modified Eagle's medium (MEM) (high glucose) and a penicillin-streptomycin solution (5000 units/mg penicillin and 5000 mg/ml streptomycin) were obtained from Gibco Laboratories (Grand Island, NY, U.S.A.). Bovine serum albumin (BSA), genistein, glycitein, resveratrol, quercetin, (ϩ)catechin, and EGCg were obtained from Sigma Chemical (St. Louis, MO, U.S.A.). All other chemicals were reagent grade from Wako Pure Chemical Industries (Osaka, Japan). All water used was glass-distilled.Animals Male Wistar rats (4 weeks old) were obtained from Japan SLC (Hamamatsu, Japan). For 7 d the animals were fed commercial laboratory chow (solid) containing 57.4% carbohydrate, 1.1% Ca, and 1.1% P at a room temperature of 25°C, and were given distilled water freely.Bone Culture The femurs were removed aseptically after exsanguination and soaked in ice-cold 0.25 M sucrose solution. The femur was cleaned of soft tissue and marrow, and the diaphysis and metaphysis (not containing epiphyseal tissue) were separated. The femoral-diaphyseal and -metaphyseal tissues were cut into small pieces. Femoral-diaphys...

Whey Protein Complexes with Green Tea Polyphenols: Antimicrobial, Osteoblast-Stimulatory, and Antioxidant Activities

“…On the other hand, GTE caused a decrease in ALP activity, often reducing the activity levels by ≥50% in wells with no GTE added. This is in agreement with Yamaguchi and Ma [2001] concerning the effect of polyphenols on ALP activity in rat femoral tissues; they concluded that EGCG (0.1 mM) significantly inhibited ALP activity.…”

Moderate alcohol consumption and increased bone mineral density: potential ethanol and non-ethanol mechanisms

“…5 mM-EGCG. In contrast to all these studies Yamaguchi & Jie (2001) have observed no positive effects of either catechin or EGCG (0 . 1-100 mM) on either bone calcification or alkaline phosphatase activity in femoral diaphyseal and metaphyseal tissues of rats in vitro.…”

Isoflavone and Bone Metabolism: Its Cellular Mechanism and Preventive Role in Bone Loss.

“…We determined the effect of polyphenols [glycitein, resveratol, quercetin, catechin, and (-)-epigallocatechin gallate (EGCg)] on bone calcification in vitro. 20) Of various polyphenols used, genistein was found to have a unique anabolic effect on bone calcification as shown in Fig. 2.…”

“…20) Resveratol, catechin, and (-1)-epigallocatechin gallate, which are polyphenols in food, do not have an anabolic effect on bone calcification. 20) A phytoestrogen genistein has a unique anabolic effect on bone metabolism.…”