Sciadopitysin protects osteoblast function via its antioxidant activity in MC3T3-E1 cells

YBX1 promotes type H vessel-dependent bone formation in an m5C-dependent manner

RNA-binding proteins (RBPs) interact with RNA and ubiquitously regulate RNA transcripts during their life cycle, playing a fundamental role in the progression of angiogenesis-related diseases. In the skeletal system, endothelium-dependent angiogenesis is indispensable for bone formation. However, the role of RBPs in endothelium-dependent bone formation is unclear. Here, we show that RBP-Y-box-binding protein 1 (YBX1) was strongly reduced in the bone vasculature of ovariectomy (OVX) mice. Endothelial cell-specific deletion of Ybx1 impaired CD31-high, endomucin-high (CD31hiEMCNhi) endothelium morphology and resulted in low bone mass whereas Ybx1 overexpression promoted angiogenesis-dependent osteogenesis and ameliorated bone loss. Mechanistically, YBX1 deletion disrupted CD31, EMCN, and bone morphogenetic protein 4 (BMP4) stability in an m5C-dependent manner and blocked endothelium-derived BMP4 release, thereby inhibiting osteogenic differentiation of bone mesenchymal stromal cells. Administration of recombinant BMP4 protein restored impaired bone formation in Ybx1 deletion mice. Tail vein injection of CD31-modified polyethylene glycol-poly (lactic-co-glycolic acid) carrying sciadopitysin, a natural YBX1 agonist, pharmacologically partially reversed CD31hiEMCNhi vessels' decline and improved bone mass in both OVX and aging animals. These findings demonstrated the role of RBP-YBX1 in angiogenesis-dependent bone formation and provided a therapeutic approach for ameliorating osteoporosis.

Splicing factor YBX1 regulates bone marrow stromal cell fate during aging

Senescence and altered differentiation potential of bone marrow stromal cells (BMSCs) lead to age-related bone loss. As an important posttranscriptional regulatory pathway, alternative splicing (AS) regulates the diversity of gene expression and has been linked to induction of cellular senescence. However, the role of splicing factors in BMSCs during aging remains poorly defined. Herein, we found that the expression of the splicing factor Y-box binding protein 1 (YBX1) in BMSCs decreased with aging in mice and humans. YBX1 deficiency resulted in mis-splicing in genes linked to BMSC osteogenic differentiation and senescence, such as Fn1, Nrp2, Sirt2, Sp7, and Spp1, thus contributing to BMSC senescence and differentiation shift during aging. Deletion of Ybx1 in BMSCs accelerated bone loss in mice, while its overexpression stimulated bone formation. Finally, we identified a small compound, sciadopitysin, which attenuated the degradation of YBX1 and bone loss in old mice. Our study demonstrated that YBX1 governs cell fate of BMSCs via fine control of RNA splicing and provides a potential therapeutic target for age-related osteoporosis.

Antioxidant Activity of Natural Samwirin A: Theoretical and Experimental Insights

Samwirin A (SW), a natural compound isolated from Sambucus williamsii or Rourea harmandiana, is known to exhibit potent antiosteoporosis activity and promote cell proliferation in rat osteoblast-like UMR 106 cells. Antiosteoporosis activity suggests that the compound must also exhibit antioxidant activity but this has not been studied thus far. In the present study, the antioxidant activity of SW was examined by experimental and computational studies. It was found that SW exhibits good hydroperoxyl scavenging activity, particularly in water at physiological pH (k overall = 1.01 × 107 M-1 s-1). The single-electron transfer mechanism defines the HOO• + SW reaction in water, while the activity in the lipid medium is moderate and it follows the formal hydrogen transfer mechanism. The rate constant of the HOO• scavenging reaction in the aqueous solution is about 78 times higher than the reference compound Trolox. The computational results are in line with experimental data underscoring that SW is a promising radical scavenger in aqueous media at physiological pH.

Activation of PI3K/PKB/GSK-3β signaling by sciadopitysin protects cardiomyocytes against high glucose-induced oxidative stress and apoptosis

Diabetic cardiomyopathy (DCM), a diabetes complication, accounts for diabetes-associated morbidity, mortality, and heart failure. Biflavonoids have been demonstrated to possess extensive pharmacological properties, such as antidiabetic and antioxidant activities. Our study aimed to explore the effects of sciadopitysin, a type of biflavonoid, on DCM and the mechanism involved. An experimental cell model was established in AC16 cardiomyocytes by exposure to high glucose (HG). Cell injury was estimated by detecting cell viability and lactate dehydrogenase (LDH) release. Oxidative stress was determined by measuring malondialdehyde (MDA) level and activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT). Apoptosis was assessed by flow cytometry analysis, caspase-3/7 activity assay, and Western blot analysis of cytochrome C (Cyt C) expression. Alternation of the phosphatidylinositol-3 kinase (PI3K)/protein kinase B (PKB)/glycogen synthase kinase-3β (GSK-3β) pathway was detected by Western blot. Results showed that HG exposure reduced viability and increased LDH release in AC16 cells, which was abolished by sciadopitysin treatment. Sciadopitysin inhibited HG-induced oxidative stress, as evidenced by the reduced MDA content, and the increased activities of SOD, CAT, and GSH-Px. Sciadopitysin suppressed HG-induced apoptosis, an increase of caspase-3/7 activity, and Cyt C expression in AC16 cells. Mechanistically, sciadopitysin activated the PI3K/PKB/GSK-3β pathway under HG stimulation in AC16 cells. Inhibition of PI3K/PKB/GSK-3β pathway by LY294002 blocked the effects of sciadopitysin on HG-induced injury, oxidative stress, and apoptosis in AC16 cells. Summarily, sciadopitysin alleviated HG-caused oxidative stress and apoptosis in cardiomyocytes by activating the PI3K/PKB/GSK-3β pathway.

Protective effects of sciadopitysin against methylglyoxal-induced degeneration in neuronal SK-N-MC cells

The accumulation of advanced glycation end products (AGEs) causes metabolic dysfunction and neuronal cell damage. Methylglyoxal (MG) is a major glycating agent that reacts with basic residues present in proteins and promotes the formation of AGEs. Sciadopitysin, a type of biflavonoid, exerts protective effects against neuronal cell damage; however, the underlying mechanisms have not been studied. This study aimed to investigate the mechanisms underlying the protective effects of sciadopitysin against MG-mediated cytotoxicity in SK-N-MC neuroblastoma cells. Our results demonstrated that pretreatment of SK-N-MC cells with sciadopitysin improved the cell viability that was inhibited by MG and inhibited the apoptosis induced by MG. Sciadopitysin attenuated intracellular Ca²⁺ , NOX4 levels, oxidative stress, and MG-protein adduct levels, and increased nuclear Nrf2 and glyoxalase 1 levels in the presence of MG. These results suggest that sciadopitysin exerts neuroprotective effects against MG-induced death of human SK-N-MC cells via its antioxidative action. This study highlights sciadopitysin as a promising candidate for antioxidant therapy and designing natural drugs against AGE-induced neurodegenerative disorders.

Black and Green Tea as Well as Specialty Teas Increase Osteoblast Mineralization with Varying Effectiveness

Many human studies suggest a benefit of tea consumption on bone health. The study objective was to compare the ability of different tea types to promote mineralization. Saos-2 cells underwent mineralization (5 days) in the presence of tea (white: WT, green: GT, black: BT, green rooibos: GR, or red rooibos: RR; 1 μg/mL of polyphenols) or control. Total polyphenol content (TPC, Folin-Ciocalteu's reagent), antioxidant capacity (2,2-diphenyl-1-picrylhydrazyl [DPPH] scavenging), mineralization (Alizarin Red staining), gene expression quantitative reverse transcription PCR (RT-qPCR), and cell activity (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay) were determined. TPC was highest in GT and BT. The ability of each tea to inhibit DPPH also differed (WT, GT > RR) after normalizing for polyphenol quantity. Each tea increased mineralization and differences were observed among types (GT/BT/GR/RR > WT, GT = BT = GR, RR > BT/GT). mRNA expression of alkaline phosphatase (ALP) and ectonucleotide pyrophosphatase/phosphodiesterase (NPP1) remained unchanged, whereas osteopontin (OPN) and sclerostin (SOST) were reduced in cells treated with tea, regardless of type. At 24- and 48-h postexposure to tea, cell activity was greater in cells receiving any of the teas compared with vehicle control. Supplementation increased mineralization regardless of tea type with both rooibos teas and black tea stimulating greater mineralization than WT, whereas green tea is similar to the others. While future study is needed to confirm in vivo effects, the results suggest that consuming any of the teas studied may benefit bone health.

Coupling Ultrasound with Heat-Reflux to Improve the Extraction of Quercetin, Kaempferol, Ginkgetin and Sciadopitysin from Mairei Yew Leaves

The coupling of ultrasound and heat–reflux extraction (UHRE) was developed for separation for quercetin (QU), kaempferol (KA), ginkgetin (GI) and sciadopitysin (SC) from Mairei Yew leaves. The Box–Behnken design was used to optimize the UHRE conditions for obtaining the maximum yield of flavonoids. The optimal extraction conditions were as follows: boiling 80% methanol (V/V) for extraction solvent, 20 min for the extraction time, 200 W for the ultrasonic power and 26 mL/g for the liquid–solid ratio. By UHRE, the yields of QU, KA, GI and SC were, respectively, 0.109, 0.406, 0.031 and 0.355 mg/g, and total yield of four flavonoids was 0.901 mg/g, which were, respectively, 1.25-fold and 1.23-fold higher than those by using ultrasonic-assisted extraction (UAE) and heating reflux extraction (HRE). Moreover, the extraction time for the equilibrium yields of flavonoids using UHRE was 83.3% and 27.8%, respectively, less than the corresponding time using UAE and HRE. Compared with HRE and UAE, UHRE showed the increase of cell disruption degree as observed by scanning electron microscopy, which may be the reason for high yield and rapid extraction of target compounds.

Validated LC-MS/MS method for the quantification of sciadopitysin in rat plasma and its application to pharmacokinetic and bioavailability studies in vivo

A sensitive and rapid LC-MS/MS method was developed and validated for quantitation of sciadopitysin in rat plasma using amentoflavone as an internal standard. Sample processing was accomplished after deproteinization with 150 μL aliquot of acetonitrile. Chromatographic separation was achieved using an Agela C₁₈ column with an isocratic mobile phase comprising 2 mm ammonium acetate-acetonitrile (35:65, v/v) at a flow rate of 0.4 mL/min. Detection was performed by selection reaction monitoring on a triple-quadrupole mass spectrometer following the transitions m/z 579 → 547 and 537 → 375 for sciadopitysin and internal standard, respectively, in the negative ionization mode. The calibration curve was linear from 2.90 to 1160 ng/mL for sciadopitysin. Intra- and inter-day precisions were in the ranges 4.1-11.4 and 5.7-9.1% for sciadopitysin. Sciadopitysin was stable under different stability conditions. The validated assay was applied to pharmacokinetic and bioavailability studies in rats.

Antioxidant and Anti-Osteoporotic Activities of Aromatic Compounds and Sterols from Hericium erinaceum

Hericium erinaceum, commonly called lion's mane mushroom, is a traditional edible mushroom widely used in culinary applications and herbal medicines in East Asian countries. In this study, a new sterol, cerevisterol 6-cinnamate (6), was isolated from the fruiting bodies of H. erinaceum together with five aromatic compounds 1-5 and five sterols 7-11. The chemical structures of these compounds were elucidated using chemical and physical methods and comparison of HRESIMS, ¹D-NMR (¹H, 13C, and DEPT) and 2D-NMR (COSY, HMQC, HMBC, and NOESY) spectra with previously reported data. The antioxidant and anti-osteoporotic activities of extracts and the isolated compounds 1-11 were investigated. All compounds exhibited peroxyl radical-scavenging capacity but only compounds 1, 3, and 4 showed potent reducing capacity. Moreover, compounds 1, 2, 4, and 5 showed moderate effects on cellular antioxidant activity and inhibited the receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclastic differentiation. These results suggested that H. erinaceum could be utilized in the development of natural antioxidant and anti-osteoporotic nutraceuticals and functional foods.

Pinacidil protects osteoblastic cells against antimycin A-induced oxidative damage

The present study aimed to investigate the protective effect of a non-selective mitochondrial adenosine triphosphate (ATP)-sensitive potassium channel (mito-KATP) opener, pinacidil, on antimycin A-induced oxidative damage in osteoblastic MC3T3-E1 cells. Antimycin A inhibits mitochondrial electron transport by binding to complex III. Osteoblastic MC3T3-E1 cells were treated with antimycin A in the presence or absence of pinacidil and markers of mitochondrial function and oxidative stress were subsequently examined. The effects of pinacidil on the activation of phosphoinositide 3-kinase (PI3K), Akt and cyclic adenosine monophosphate‑responsive element-binding protein (CREB) were also examined. In osteoblastic MC3T3-E1 cells exposed to antimycin A, pinacidil inhibited antimycin A-induced cell death. The protective effects of pinacidil on cell survival were prevented by the addition of LY294002 (a PI3K inhibitor), an Akt inhibitor or auranofin [a thioredoxin reductase (TrxR) inhibitor], but not by KATP channel inhibitor glibenclamide. Pinacidil inhibited antimycin A-induced inactivation of PI3K and Akt as well as phosphorylation of CREB and TrxR. Furthermore, pinacidil prevented antimycin A-induced mitochondrial superoxide release, mitochondrial membrane potential dissipation, reduced ATP synthesis and intracellular [Ca2+] elevation. In conclusion, these results suggested that pinacidil may rescue osteoblastic cells from antimycin A-induced cellular damage, potentially via antioxidant activity and restoration of mitochondrial function, which are mediated in part by the PI3K/Akt/CREB signaling pathway.

Evaluation of the antioxidant and anti-osteoporosis activities of chemical constituents of the fruits of Prunus mume

The present study investigated the antioxidant and anti-osteoporosis activities of phytochemicals in the fruits of Prunus mume. From the methanol extract, three new acylated sucroses, mumeoses P-R (1-3), were isolated together with 20 known compounds (4-23). Compounds 1-3 showed potent peroxyl radical-scavenging activities and 12-19 showed both potent peroxyl radical-scavenging and reducing activities. The anti-osteoporosis activity was evaluated using murine pre-osteoblastic MC3T3-E1 cells and pre-osteoclastic RAW 264.7 cells. Compounds 2 and 3 (cis-trans isomers), 5, 7, 8, and 10 significantly stimulated the differentiation of pre-osteoblastic MC3T3-E1 cells to increase collagen synthesis or mineralization functions of osteoblasts, while compounds 5, 6, 9, 10, 12, 14-16, 18, 20, and 22 significantly suppressed tartrate-resistant acid phosphatase activity in receptor activator of nuclear factor-κB ligand-induced osteoclastic RAW 264.7 cells. These results indicated that the fruits of P. mume are an excellent source of antioxidant and anti-osteoporosis phytochemicals.