Phytoestrogens represent a family of plant polyphenolic compounds such as flavonoids and lignans that have been shown to have both estrogenic and antiestrogenic properties. Estrogen exerts a strong protective effect against osteoporosis, and increasing evidences suggest that phytoestrogens may also stimulate bone formation. Previously, we demonstrated that feeding diets containing oil cake of roasted safflower seeds significantly attenuated the process of osteoporosis in ovariectomized rats. In the present study, we therefore investigated effects of polyphenolic compounds extracted from roasted safflower seeds on proliferation and differentiation of osteoblastic cells to find out whether the compounds stimulate bone formation. Tested six polyphenolic compounds are flavonoids (Apigenin 7-ο-glucoside and Acacetin), lignans (Matairesinol and 2-hydroxyarctigenin) and serotonins (N-Feruloylserotonin and N-(ρ-Coumaroyl) serotonin). Like 17β-estradiol (E2) and genistein, an isoflavonoid isolated from soybean, all the tested phytoestrogens also stimulated proliferation of rat osteosarcoma cell line, ROS 17/2.8 in a dose-dependent fashion (10-15～10-6 M): especially matairesinol, acacetin and N-feruloylserotonin were more effective on osteoblast cell growth. To examine effects on differentiation, osteoblast-like cell KS483 were treated with E2 and polyphenols for 4 wks and examined mineral deposition of nodules by von Kossa staining. Lignans, flavonoids and serotonins also enhanced both nodule formation and calcium deposition. Polyphenols stimulated mRNA expression of protein markers of differentiation such as alkaline phosphatase, typeⅠcollagen and osteopontin. These data provide the first evidence that poly- phenolic compounds such as flavonoids, lignans and serotonins extracted from safflower seeds directly stimulate the proliferation and differentiation of the cultured osteoblast cells.
Source: Korean Journal of Physiology & Pharmacology.2000 Oct;4(Suppl):S18-S18
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