Category Archives: Silymarin

Silibinin Promotes Osteoblasts In Vitro


Silibinin promotes osteoblast differentiation of human bone marrow stromal cells via bone morphogenetic protein signaling.

Silibinin is the major active constituent of the natural compound silymarin; several studies suggest that silibinin possesses antihepatotoxic properties and anticancer effects against carcinoma cells. However, no study has yet investigated the effect of silibinin on osteogenic differentiation of human bone marrow stem cells (hBMSCs). The aim of this study was to evaluate the effect of silibinin on osteogenic differentiation of hBMSCs. In this study, the hBMSCs were cultured in an osteogenic medium with 0, 1, 10 or 20 μmol/l silibinin respectively. hBMSCs viability was analyzed by cell number quantification assay and cells osteogenic differentiation was evaluated by alkaline phosphatas (ALP) activity assay, Von Kossa staining and real time-polymerase chain reaction (RT-PCR). We found that silibinin promoted ALP activity in hBMSCs without affecting their proliferation. The mineralization of hBMSCs was enhanced by treatment with silibinin. Silibinin also increased the mRNA expressions of Collagen type I (COL-I), ALP, Osteocalcin (OCN), Osterix, bone morphogenetic protein-2 (BMP-2) and Runt-related transcription factor 2 (RUNX2). The BMP antagonist noggin and its receptor kinase inhibitors dorsomorphin and LDN-193189 attenuated silibinin-promoted ALP activity. Furthermore, BMP-responsive and Runx2-responsive reporters were activated by silibinin treatment. These results indicate that silibinin enhances osteoblast differentiation probably by inducing the expressions of BMPs and activating BMP and RUNX2 pathways. Thus, silibinin may play an important therapeutic role in osteoporosis patients by improving osteogenic differentiation of BMSCs.

Ying X, Sun L, Chen X, Xu H…
Eur. J. Pharmacol. Dec 2013
PMID: 24076187

Silibinin Increases Osteoblasts and Inhibits Osteoclasts in Mouse Cells


Osteoblastogenesis and osteoprotection enhanced by flavonolignan silibinin in osteoblasts and osteoclasts.

Bone-remodeling imbalance induced by decreased osteoblastogenesis and increased bone resorption is known to cause skeletal diseases such as osteoporosis. Silibinin is the major active constituent of silymarin, the mixture of flavonolignans extracted from blessed milk thistle (Silybum marianum). Numerous studies suggest that silibinin is a powerful antioxidant and has anti-hepatotoxic properties and anti-cancer effects against carcinoma cells. This study investigated that silibinin had bone-forming and osteoprotective effects in in vitro cell systems of murine osteoblastic MC3T3-E1 cells and RAW 264.7 murine macrophages. MC3T3-E1 cells were incubated in osteogenic media in the presence of 1-20 µM silibinin up to 15 days. Silibinin accelerated cell proliferation and promoted matrix mineralization by enhancing bone nodule formation by calcium deposits. In addition, silibinin furthered the induction of osteoblastogenic biomarkers of alkaline phosphatase, collagen type 1, connective tissue growth factor, and bone morphogenetic protein-2. Differentiated MC3T3-E1 cells enhanced secretion of receptor activator of nuclear factor-κB ligand (RANKL) essential for osteoclastogenesis, which was reversed by silibinin. On the other hand, RAW 264.7 cells were pre-incubated with 1-20 µM silibinin for 5 days in the presence of RANKL. Non-toxic silibinin markedly attenuated RANK transcription and intracellular adhesion molecule-1 expression elevated by RANKL, thereby suppressing the differentiation of macrophages to multi-nucleated osteoclasts. It was also found that silibinin retarded tartrate-resistant acid phosphatase and cathepsin K induction and matrix metalloproteinase-9 activity elevated by RANKL through disturbing TRAF6-c-Src signaling pathways. These results demonstrate that silibinin was a potential therapeutic agent promoting bone-forming osteoblastogenesis and encumbering osteoclastic bone resorption.

Kim JL, Kang SW, Kang MK, Gong JH…
J. Cell. Biochem. Jan 2012
PMID: 21898547

Resveratrol Stimulates Osteocalcin in Rat Cells


Estradiol and resveratrol stimulating effect on osteocalcin, but not osteonectin and collagen-1alpha gene expression in primary culture of rat calvarial osteoblast-like cells.

Evidence is available that some endocrine disruptors, acting as selective estrogen receptor modulators (SERMs), interfere with osteoblast differentiation and function. Therefore, we investigated whether 17beta-estradiol, bisphenol-A (BSP), silymarin, genistein, resveratrol, procymidone, linurone and benzophenone-3 (BP3) modulate differentiation of rat calvarial osteoblast-like (ROB) cells in primary in vitro culture. Disruptors were added at day 18 of culture and cells were harvested 48 h later. Real time-PCR revealed that estradiol and resveratrol enhanced osteocalcin mRNA expression in ROB cells, while other disruptors were ineffective. The expression of osteonectin and collagen-1alpha was not affected by any disruptor. Estradiol, resveratrol, genistein and BSP stimulated the proliferative activity of ROB cells. In contrast, procymidone and linurone inhibited the proliferative activity, and silymarin and BP3 were ineffective. The conclusion is drawn that i) only resveratrol is able, like estradiol, to stimulate the specialized functions of ROB cells, and ii) the proliferative activity of ROB cells is more sensitive to endocrine disruptors, some of which could probably act via a mechanism independent of their SERM activity.

Rucinski M, Ziolkowska A, Hochol A, Pucher A…
Int. J. Mol. Med. Oct 2006
PMID: 16964405

Silymarin is a Beta Estrogen Agonist with Antiosteoporotic Effects in Ovariectomized Rats


Silymarin is a selective estrogen receptor beta (ERbeta) agonist and has estrogenic effects in the metaphysis of the femur but no or antiestrogenic effects in the uterus of ovariectomized (ovx) rats.

Silymarin is a widely used standardized mixture of flavonolignans and its major component Silybinin binds to cytosolic estrogen receptors. Here, we demonstrate that this binding is exclusive to the estrogen receptor beta (ERbeta). Treatment of ovariectomized (ovx) rats with silymarin or estradiol (E2) may allow differentiation of biological effects mediated by the ERalpha or ERbeta. E2 inhibited serum LH, cholesterol, LDL and HDL concentrations in the blood and increased gene expression of IGF1, HbEGF and C3 in the uterus, while silymarin was totally ineffective or antagonistic in altering these parameters. Both, E2 and silymarin inhibited expression of uterine ERbeta gene. Hence, in the pituitary, liver (where the lipoproteins are synthesized) and uterus E2 acts primarily via the ERalpha. Exclusive estrogenic effects of silymarin were observed in the metaphysis of the femur (MF), on osteoblast parameters (gene expression of IGF1, TGFbeta1, osteoprotegerin, collagen-1alpha1, osteocalcin (OC)) and on the osteoclast activity marker tartrate resistant acid phosphatase (TRAP) gene expression of adult ovx rats. Our RT-PCR method detects ERbeta gene expression in all organs including developing bones but not in the MF of adult ovx rats. We conclude therefore, that the effects of silymarin in this part of the bone cannot be exerted via the ERalpha because it does not bind to this receptor subtype. Despite the failure to detect ERbeta mRNA in the MF of our animals the possibility exists that ERbeta protein is present and may mediate the effects of silymarin. Another possibility may be that the effect of silymarin and therefore possibly also of E2 in the MF may be mediated via other possibly not yet identified receptors or via an ERbeta splice variant which is not detected by our PCR-method.

Seidlová-Wuttke D, Becker T, Christoffel V, Jarry H…
J. Steroid Biochem. Mol. Biol. Aug 2003
PMID: 14568570

Silymarin has Antiosteoporotic and SERM Activity in Rats


Evidences for antiosteoporotic and selective estrogen receptor modulator activity of silymarin compared with ethinylestradiol in ovariectomized rats.

Recently, growing multiple uses of silymarin (SIL) as a complementary and alternative medicine, for alcohol-induced liver disease, acute and chronic viral hepatitis, as well as some other nonhepatic indications have been reported. Therefore, more attention should be paid for the hormonal side effects of SIL. Since the available data on the possible estrogenic effects of SIL is rather rare, this study aimed to further elucidate the different estrogenic effects and antiosteoporotic activity of SIL in ovariectomized (OVX) rats. OVX rats were treated chronically (12 weeks) with ethinylestradiol (EE) or SIL. Uterine and body weight were measured in all animals. Biochemical markers of bone formation (total alkaline phosphatase (ALP), calcium, phosphorus and osteocalcin), endocrinological analysis (estradiol (E2), luteinizing hormone (LH), follicle stimulating hormone (FSH) and parathyroid hormone (PTH)) and serum total cholesterol and total lipids were estimated. Formalin fixed femora and uteri specimens were used for histopathological examination. In addition, the binding property of SIL to the two estrogen receptors (ER) subtypes was tested by molecular docking. EE (strong) and SIL (mild) stimulated uterine weight (increased uterus hyperplastic endometrial glands) but EE only prevented body weight gain following OVX. Treatment of OVX rats with both EE and SIL resulted in protection of trabecula thickness, decreased serum levels of ALP and increased serum levels of both calcium and phosphorus. In contrast to EE, SIL did not decrease OVX induced serum osteocalcin. EE not SIL decreased serum cholesterol, total lipids, LH and FSH and increased serum E2. Both EE and SIL increased serum PTH. The docking study revealed a high affinity of SIL towards ERbeta. In conclusion, findings derived in the present study presented an overview of SIL many estrogenic effects in OVX rats. SIL significantly prevents the bone loss in rats induced by OVX with mild proliferative effects in uterus. The observed effects may be due to additive beneficial effect of SIL on bone either due to direct interaction with ERbeta or increasing bone formation parameters including calcium, phosphorus, osteocalcin and PTH.

El-Shitany NA, Hegazy S, El-Desoky K
Phytomedicine Feb 2010
PMID: 19577454