Icariin is more potent than genistein in promoting osteoblast differentiation and mineralization in vitro

Abstract

There has been a strong interest in searching for natural therapies for osteoporosis. Genistein, an isoflavone abundant in soy, and icariin, a prenylated flavonol glycoside isolated from Epimedium Herb, have both been identified to exert beneficial effects in preventing postmenopausal bone loss. However, the relative potency in osteogenesis between the individual phytoestrogen flavonoids remains unknown. The present study compared ability of genistein and icariin in enhancing differentiation and mineralization of cultured rat calvarial osteoblasts in vitro. Dose-dependent studies in osteoblast differentiation measuring alkaline phosphatase (ALP) activity revealed optimal concentrations of genistein and icarrin for stimulating osteogenesis to be both at 10(-5) M. Time course studies comparing the two compounds both at 10(-5) M demonstrated that icariin treatment always produced higher ALP activity, more and larger areas of CFU-F(ALP) colonies and mineralized nodules, more osteocalcin secretion, and calcium deposition, and a higher level of mRNA expression of osteogenesis-related genes COL1α2, BMP-2, OSX, and RUNX-2. However, they inhibited the proliferation of osteoblasts to a similar degree. In conclusion, although future in vivo studies are required to investigate whether icariin is more efficient in improving bone mass and/or preventing bone loss, our in vitro studies have demonstrated that icariin has a stronger osteogenic activity than genistein. In addition, while the prenyl group on C-8 of icariin could be the active group that takes part in osteoblastic differentiation and explains its greater potency in osteogenesis, mechanisms of action, and reasons for the relative potency of icariin versus genistein need to be further studied.

Quantitative kinetics analysis of BMP2 uptake into cells and its modulation by BMP antagonists

“…Using chlorpromazine to block clathrin and genistein or nystatin to block caveolin-mediated uptake, we could clearly identify clathrin-mediated endocytosis as the major route of BMP2 internalization. Genistein reduced BMP2 internalization at later time points, which could be explained by complementary routes of clathrin-and caveolinmediated endocytosis, as suggested in the model of Hartung et al (Hartung et al, 2006), but may be better explained by other mechanisms resulting from inhibition of tyrosine kinases by genistein (Aoki et al, 1999;Sharma et al, 2004;Ma et al, 2011). In fact, nystatin, which is also commonly used to block caveolinmediated internalization (Rothberg et al, 1992;Di Guglielmo et al, 2003;Chen, 2009), did not inhibit BMP2 uptake.…”

“…8A). Chlorpromazine reduced FL-BMP2 uptake at all time points, to a lesser extent at 3 h and more clearly after 6 and 12 h. Upon treatment with genistein, reduced uptake was only clearly visible after 12 h. At this time point the inhibition of uptake by genistein could be a secondary effect not related to caveolin-mediated internalization but rather result from the tyrosine kinase inhibitor activity of genistein (Aoki et al, 1999;Ma et al, 2011). Co-incubation with both inhibitors showed an additive effect on FL-BMP2 internalization at the 12 h time point, indicating complementary activity after this extended incubation (Fig.…”

“…To identify which of these mechanisms mediated the observed BMP2 ligand internalization, we pre-incubated cells for 30 min with chlorpromazine, a pharmacological compound blocking clathrin-mediated endocytosis, or alternatively with genistein, which prevents caveolin-mediated uptake by blocking cav-1 phosphorylation (Aoki et al, 1999;Sharma et al, 2004;Ma et al, 2011). Both inhibitors differently reduced FL-BMP2 internalization (Fig.…”

Chinese single herbs and active ingredients for postmenopausal osteoporosis: From preclinical evidence to action mechanism

“…Total flavones of Epimedium (TFE) inhibited reduction of procollagen type I N-terminal propeptide (PINP), and increased serum osteocalcin and type I collagen in OVX rats (13,14). Icariin, one of the major components of Herba Epimedium, decreased activities of serum tartrate-resistant acid phosphatase (TRAP) and bioactive components could stimulate the proliferation, differentiation and mineralization of osteoblasts (12,(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40), suppress the adipogenesis of bone marrow-derived mesenchymal stem cells (BMSCs) (41)(42)(43)(44), inhibit the proliferation and differentiation of osteoclasts (45)(46)(47), and induce apoptosis and cell cycle arrest and suppress bone resorption of osteoclasts (48). In addition, icariin was found to significantly attenuate oxidative stress and apoptosis and preserve viability and osteogenic potential of osteoblasts exposed to hypoxia, which indicated that its anti-osteoporotic effect might be attributed to its anti-hypoxic activity (49).…”

A systematic review on biological activities of prenylated flavonoids

“…Prenylated flavonoids generally showed greater binding energies than those of the non-prenylated flavonoids. It was concluded that the prenylated flavonoids from Lonchocarpus possibly owe the cytotoxic activity by suppressing the activity of some enzymes: aromatase (CYP 19), fatty acid synthase (FAS), xanthine oxidase (XO), cyclooxygenases (COX-1 and COX-2), lipoxygenase (LOX-3), ornithine decarboxylase (ODC), protein tyrosine kinase (PTK), phosphoinositide 3-kinase (PI3K), protein kinase C (PKC), topoisomerase II (ATP-binding site), ATPbinding cassette (ABC) transporter and phospholipase A(2) (PLA) (Ma et al, 2011).…”