Neuroprotective Effects of Ugonin K on Hydrogen Peroxide-Induced Cell Death in Human Neuroblastoma SH-SY5Y Cells

A review on osteoclast diseases and osteoclastogenesis inhibitors recently developed from natural resources

Natural products have been investigated as potential candidates of novel therapeutics and play a crucial role in advanced medicinal drugs. Natural resources, including local medicinal plants (especially folk medicinal plants), animals, bacteria, and fungi have been used for more than a century, and are precious gifts from nature, providing potential medicines with high safety. Osteoclast-related diseases, such as osteoporosis, rheumatoid arthritis, Paget's disease, osteoclastoma, and periprosthetic osteolysis, are currently the most common reasons for bone inflammation, pain and fractures, resulting in low quality of life. However, the curative effects of current therapeutic drugs for these osteoclast-related diseases are limited, and long-term treatment is needed. Further, in severe cases, surgical treatments are necessary, which may cause unaffordable expenses and subsequent influences such as neuralgia, mental stress, and even development of cancer. Thus, safer inhibitors and potential drugs with enhanced curative effects and quick relief are needed to treat patients with osteoclast diseases. This review aims to introduce the main osteoclast-related diseases and some of the recently developed naturally sourced inhibitors against osteoclastogenesis, also it is desired to attract people's attention on using widely available natural resources for the evolution of new types of osteoclast inhibitors with minimal or no side-effects upon long-term treatments.

Inhibitory Effect of Probenecid on Osteoclast Formation via JNK, ROS and COX-2

Probenecid is a representative drug used in the treatment of gout. A recent study showed that probenecid effectively inhibits oxidative stress in neural cells. In the present study, we investigated whether probenecid can affect osteoclast formation through the inhibition of reactive oxygen species (ROS) formation in RAW264.7 cells. Lipopolysaccharide (LPS)-induced ROS levels were dose-dependently reduced by probenecid. Fluorescence microscopy analysis clearly showed that probenecid inhibits the generation of ROS. Western blot analysis indicated that probenecid affects two downstream signaling molecules of ROS, cyclooxygenase 2 (COX-2) and c-Jun N-terminal kinase (JNK). These results indicate that probenecid inhibits ROS generation and exerts antiosteoclastogenic activity by inhibiting the COX-2 and JNK pathways. These results suggest that probenecid could potentially be used as a therapeutic agent to prevent bone resorption.

Study of Electrical Stimulation with Different Electric-Field Intensities in the Regulation of the Differentiation of PC12 Cells

The strategy of using electrical stimulation (ES) to promote the neural differentiation and regeneration of injured nerves is proven feasible. Study of the possible molecular mechanisms in relation to this ES promotion effect should be helpful for understanding the phenomenon. In this study, it was identified that the neuronal differentiation of PC12 cells was enhanced when the electric field intensity was in the range of 30-80 mV/mm, and a lower or higher electric-field intensity displayed inferior effects. Under ES, however, levels of intracellular reactive oxygen species (ROS), intracellular Ca²⁺ dynamics, and expression of TREK-1 were measured as being gradually increasing alongside higher electric-field intensity. In trying to understand the relationship between the ES enhancement on differentiation and these variations in cell activities, parallel experiments were conducted by introducing exogeneous H₂O₂ into culture systems at different concentrations. Similarly, the effects of H₂O₂ concentration on the neuronal differentiation of PC12 cells, intracellular ROS and Ca²⁺ levels, and TREK-1 expression were systematically characterized. In comparative studies, it was found in two cases that ES of 50 mV/mm for 2 h/day and H₂O₂ of 5 μM in culture medium shared comparable results for intracellular ROS and Ca²⁺ levels and TREK-1 expression. Higher H₂O₂ concentrations (e.g., 10 and 20 μM) demonstrated adverse effects on cell differentiation and caused DNA damage. A stronger ES (e.g., 100 mV/mm), being associated with a higher intracellular ROS level, also resulted in weaker enhancement of the neuronal differentiation of PC12 cells. These facts suggested that the intracellular ROS generated under ES might be an intermediate signal transducer involved in cascade reactions relative to cell differentiation.

Neuroprotective effects of chloroform and aqueous fractions of noni juice against t-Butyl hydroperoxide-induced oxidative damage in SH-SY5Y cells

Oxidative stress is more likely to cause damage to neuronal cells and mediates some neurodegenerative disorders. It is well known that natural antioxidants can prevent oxidative stress damage and become a potential therapeutic strategy. Noni juice obtained from the fruit of the tree Morinda citrifolia, as a folk medicine, has been used for over two thousand years. In the current study, the neuroprotective effect and mechanism of noni juice extracts against tert-Butyl hydroperoxide (TBHP)-induced SH-SY5Y cell damage were investigated. The results demonstrated that chloroform fraction (CF) and aqueous fraction (AF) of noni juice protected SH-SY5Y cells against TBHP-induced oxidative stress and the associated apoptosis effectively. CF and AF treatment significantly weakened the TBHP-induced cytotoxicity, reactive oxygen species generation, mitochondrial membrane depolarization, and apoptotic features. CF and AF restored cellular antioxidant enzyme activity; upregulated expression of heme oxygenase-1, catalase, and superoxide dismutase-1; and increased the nuclear accumulation of nuclear factor-erythroid 2 related factor 2 (Nrf2). The antioxidant and neuroprotection potential of CF may account for its high total phenolic and flavonoid content, while AF may be rich in polysaccharides. These results suggest that CF and AF exhibit antioxidant defense through the upregulation of Nrf2 along with endogenous antioxidants and reduce apoptosis via inhibiting the mitochondrial pathway to protect SH-SY5Y cells damaged by TBHP. CF and AF might be developed as agents for neurodegeneration prevention or therapy.

[Effect of miR-21 down-regulated by H 2O 2 on osteogenic differentiation of MC3T3-E1 cells]

Objective

To explore the effect and mechanism of miR-21 down-regulated which was induced by H ₂O ₂ on osteogenic differentiation of MC3T3-E1 cells.

Methods

MC3T3-E1 cells were cultured and passaged, and the 7th generation cells were harvested to use in experiment. The MC3T3-E1 cells were treated with different concentrations (0, 40, 80, 160, and 320 μmol/L) of H ₂O ₂. The expression of miR-21 was detected by real-time quantitative PCR (RT-PCR) and the cell viability was determined by MTS. Then the appropriate concentration of H ₂O ₂ was obtained. To analyze the effect of H ₂O ₂ on osteogenic differentiation of MC3T3-E1 cells, the MC3T3-E1 cells were divided into blank control group (group A), H ₂O ₂ group (group B), osteogenic induction group (group C), and H ₂O ₂+osteogenic induction group (group D). The expression of miR-21 and the osteogenesis related genes expressions of Runx2, osteopontin (OPN), and collagen type Ⅰ alpha 1 (Col1a1) were detected by RT-PCR. The expression of phosphatase and tensin homolog (PTEN) was detected by Western blot. The extracellular calcium deposition was detected by alizarin red staining. To analyze the effect on osteogenic differentiation of MC3T3-E1 cells after the transfection of miR-21 inhibitor and siRNA-PTEN, the MC3T3-E1 cells were divided into H ₂O ₂ group (group A1), H ₂O ₂+osteogenic induction group (group B1), H ₂O ₂+osteogenic induction+miR-21 inhibitor group (group C1), and H ₂O ₂+osteogenic induction+miR-21 inhibitor negative control group (group D1); and H ₂O ₂ group (group A2), H ₂O ₂+osteogenic induction group (group B2), H ₂O ₂+osteogenic induction+siRNA-PTEN negative control group (group C2), and H ₂O ₂+osteogenic induction+siRNA-PTEN group (group D2). The osteogenesis related genes were detected by RT-PCR and the extracellular calcium deposition was detected by alizarin red staining.

Results

The results of MTS and RT-PCR showed that the appropriate concentration of H ₂O ₂ was 160 μmol/L. The expression of miR-21 was significantly lower in group B than in group A at 1 and 2 weeks ( P<0.05). The expression of miR-21 was significantly lower in group D than in group C at 1 and 2 weeks ( P<0.05). The expression of PTEN protein was significantly lower in group C than in groups A and D ( P<0.05). The mRNA expressions of Runx2, OPN, and Col1a1 were significantly lower in group D than in group C at 1 and 2 weeks ( P<0.05). The extracellular calcium deposition in group D was obviously less than that in group C. The expression of PTEN protein was significantly higher in group C1 than in group D1 ( P<0.05). The mRNA expressions of Runx2 and OPN were significantly lower in group C1 than in groups B1 and D1 at 1 and 2 weeks ( P<0.05). The mRNA expression of Col1a1 was significantly lower in group C1 than in groups B1 and D1 at 2 weeks ( P<0.05). The extracellular calcium deposition in group C1 was obviously less than those in groups B1 and D1. The mRNA expressions of OPN and Col1a1 were significantly higher in group D2 than in groups B2 and C2 at 1 week ( P<0.05). The extracellular calcium deposition in group D2 was obviously more than those in groups B2 and C2.

Conclusion

H ₂O ₂ inhibits the osteogenic differentiation of MC3T3-E1 cells, which may be induced by down-regulating the expression of miR-21.

Hepatoprotective Effect of Ugonin M, A Helminthostachyszeylanica Constituent, on Acetaminophen-Induced Acute Liver Injury in Mice

The present study aimed to discover the possible effectiveness of Ugonin M, a unique flavonoid isolated from Helminthostachys zeylanica-a traditional Chinese medicine used as anti-inflammatory medicine-and to elucidate the potential mechanisms of Ugonin M in the acute liver injury induced by acetaminophen (APAP). In this study, Ugonin M significantly ameliorated APAP-induced histopathological changes and the typical liver function biomarkers (i.e., alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin (T-Bil)). It also affected APAP-induced abnormal lipid metabolism including total cholesterol (TC) and triglyceride (TG) in the serum. In inflammatory pharmacological action, Ugonin M suppressed the pro-inflammatory mediators such as nitric oxide (NO) and the lipid peroxidation indicator malondialdehyde (MDA). In addition, Ugonin M reinforced hemeoxygenase-1 (HO-1) protein expression and the production of antioxidant enzymes viz superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). Furthermore, inflammation-associated cytokines including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β as well as proteins such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were decreased by the pretreatment of Ugonin M. Moreover, this study found that pretreatment of Ugonin M apparently decreased nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) activation via inhibition of the degradation of NF-κB, inhibitory κB-α (IκB-α), extracellular regulated kinase (ERK), c-Jun-N-terminal (JNK), and p38 active phosphorylation. In conclusion, Ugonin M significantly showed a protective effect against APAP-induced liver injury by reducing oxidative stress and inflammation. Thus, Ugonin M could be one of the effective components of H. zeylanica that plays a major role in the treatment of inflammatory disorders.

MicroRNA‑26a protects vascular smooth muscle cells against H2O2‑induced injury through activation of the PTEN/AKT/mTOR pathway

Abdominal aortic aneurysm (AAA) is a common disease, which is characterized by the apoptosis of vascular smooth muscle cells (VSMCs). In previous years, microRNAs (miRNAs) have been associated with AAA and functionally implicated in the pathogenesis of this disease. However, the role of miRNAs in the apoptosis of VSMCs remains to be fully elucidated. The present study aimed to elucidate the role and mechanism of miRNAs in protecting against hydrogen peroxide (H₂O₂)-induced apoptosis in VSMCs. The expression of miRNAs in peripheral blood from patients diagnosed with AAA was analyzed using a microarray and reverse transcription polymerase chain reaction. A VSMC injury model induced by H₂O₂ was used to determine the potential role of miR-26a against cell injury. Cell viability, cell apoptosis and reactive oxygen species (ROS) generation were determined by a CCK8 assay, flow cytometry and a 2′,7′-DCF diacetate assay, respectively. It was observed that miRNA (miR)-26a (miR-26a-1-5p) was significantly downregulated in peripheral blood samples from patients with AAA. It was revealed that H₂O₂ treatment dose-dependently inhibited cell viability, enhanced apoptosis and induced the production of ROS, which indicated the success of the model establishment. It was also observed that miR-26a was downregulated in the VSMCs following H₂O₂ stimulation. The upregulation of miR-26a attenuated H₂O₂-induced cell injury, as evidenced by the enhancement of cell viability, and inhibition of the activity of caspase-3, apoptosis and ROS production. In addition, phosphatase and tensin homolog (PTEN), a well-known regulator of the AKT/mammalian target of rapamycin (mTOR) pathway, was found to be a direct target of miR-26a in the VSMCs and this was validated using a luciferase reporter assay. Overexpression of PTEN by pcDNA-PTEN plasmids markedly eliminated the protective effects of the overexpression of miR-26a on H₂O₂-induced cell injury. Finally, it was found that miR-26a mediated its anti-apoptotic action by reactivation of the AKT/mTOR pathway, as demonstrated by the upregulation of phosphorylated (p-)AKT and p-mTOR, and the Akt inhibitor API-2 reversing the protective effects on VSMCs mediated by miR-26a. These results indicated that miR-26a protected VSMCs against H₂O₂-induced injury through activation of the PTEN/AKT/mTOR pathway, and miR-26a may be considered as a potential prognostic biomarker and therapeutic target in the treatment of AAA.

Protective effect of gigantol against hydrogen peroxide‑induced apoptosis in rat bone marrow mesenchymal stem cells through the PI3K/Akt pathway

Bone marrow mesenchymal stem cell (BMSC) transplants are promising for the treatment of certain central nervous system diseases. However, oxidative stress is one of the major factors that may limit the survival of the transplanted BMSCs. The present study investigated the effect of pretreatment with gigantol on hydrogen peroxide (H2O2)‑induced apoptosis in rat BMSCs (rBMSCs) and the potential underlying mechanisms. The results demonstrated that gigantol pretreatment significantly inhibited H2O2‑induced apoptosis of rBMSCs. rBMSCs were incubated with 600 µM H2O2 in the absence or presence of different doses of gigantol (1‑100 µM). Cell viability and apoptosis ratios were assessed by MTT assays and flow cytometry, respectively. Morphological alterations and reactive oxygen species were measured by the fluorescent‑based methods of Hoechst staining and dichlorodihydrofluorescein diacetate, respectively. Furthermore, the protein levels of phosphorylated‑protein kinase B (Akt), B‑cell lymphoma‑2 (Bcl‑2), Bcl‑2‑associated X (Bax), caspase‑3 and caspase‑9 were investigated by western blotting. Following incubation with H2O2 for 2 h, gigantol significantly inhibited the H2O2‑induced reductions in the cell viability of rBMSCs in a dose‑dependent manner. Furthermore, gigantol upregulated Akt phosphorylation and Bcl‑2 expression, downregulated Bax expression, and reduced the expression of caspase‑3 and caspase‑9 in H2O2‑treated rBMSCs, whereas an opposite effect was detected when LY294002, an inhibitor of phosphatidylinositol 3‑kinase, was administered in combination with gigantol. These results indicate that gigantol may be developed as a promising neuroprotective agent for successful MSC transplantation in ischemic diseases.

Quality Control of the Root and Rhizome of Helminthostachys zeylanica (Daodi-Ugon) by HPLC Using Quercetin and Ugonins as Markers

Daodi-Ugon is the dried root and rhizome of Helminthostachys zeylanica (L.) Hook. and has been used for centuries in the treatment of inflammation, fever, pneumonia, burns, and various disorders. However, the chromatographic methods to determine the phytochemical composition of H. zeylanica have never been reported. This study not only aims to develop a valid high-performance liquid chromatography (HPLC) method and to establish a chromatographic fingerprint for the quality control of H. zeylanica, it also establish the proposed content limits of Quercetin, Ugonin J, and Ugonin M. An HPLC method with a RP₁₈ column (250 × 4.6 mm, 5 μm) was developed for the quantitative analysis of Quercetin, Ugonin J, and Ugonin M in H. zeylanica. A simple gradient of (A) methanol/(B) phosphoric acid in water (5–45 min, 70–80% A; 50–55 min, 80–70% A) was used and 360 nm was selected as the detection wavelength. The average contents and proposed content limits for H. zeylanica were calculated with a t-test and a measurement uncertainty test based on 20 batches of authentic H. zeylanica samples. Limits of detection (LOD), quantification (LOQ), linearity, precision, repeatability, stability, and recovery of the developed method were validated. All of the validation results of quantitative determination and fingerprinting methods were satisfactory. The developed method was then applied to assay the contents of Quercetin, Ugonin J, and Ugonin M and to acquire the fingerprints of all of the collected H. zeylanica samples. At the 99% confidence level, the calculated content limits were 56.45, 112.15, and 277.98 mg/kg for Quercetin, Ugonin J, and Ugonin M, respectively. Those validated HPLC quantitative method, fingerprinting profile, and the proposed content limits of three chemical markers that could be used in the quality control of H. zeylanica in the market.

Role and mechanism of microRNA-21 in H2O2-induced apoptosis in bone marrow mesenchymal stem cells

microRNA-21 (miR-21) contributes to anti-apoptosis, proliferation and migration in many cells, but its role in inhibiting apoptosis in bone marrow mesenchymal stem cells (BMSC) remains unclear. The aim of this study was to determine the role of miR-21 in H2O2-induced BMSC apoptosis. We used quantitative real time-polymerase chain reaction (RT-PCR) to demonstrate the level of miR-21 after treatment of BMSC with H2O2. BMSC apoptosis was induced by different concentrations of H2O2 and was decreased in miR-21-upregulated cells. The expression of PTEN, a functional target gene of miR-21 in BMSC, was regulated by miR-21. The RT-PCR results indicated that miR-21 was significantly up-regulated, and western blot analysis indicated that Bcl-2 was up-regulated, whereas the apoptosis-related genes caspase 3/9 and Bax were down-regulated in miR-21-up-regulated cells. The miR-21-up-regulated cells had significantly enhanced Akt phosphorylation, as measured by western blot analysis. LY294002, an inhibitor of Akt activation, abolished the protective effects of miR-21-up-regulated cells. These results suggest that miR-21 contributes to inhibition of apoptosis in BMSC by down-regulating PTEN, potentially via the PI3K/Akt pathway.

Evaluation of Anti-Inflammatory Effects of Helminthostachys zeylanica Extracts via Inhibiting Bradykinin-Induced MMP-9 Expression in Brain Astrocytes

Phytochemicals present in vegetables, fruits, and herbs are believed to reduce the risk of several major diseases including cardiovascular or neurodegenerative disorders. The roots of the fern Helminthostachys zeylanica (L.) Hook. (Ophioglossaceae) have been used for centuries in the treatment of inflammation and as a folk medicine in several countries. The plant has been shown to possess an array of medicinal properties, including antioxidants and anti-inflammatory activities. Moreover, a rising level of matrix metalloproteinase-9 (MMP-9) has been found in blood fluid of these patients suffering from brain inflammatory diseases, which may be considered an inflammatory biomarker in several inflammatory diseases including the central nervous system (CNS) inflammation. Previously, we have demonstrated the signaling mechanisms of bradykinin (BK)-induced MMP-9 expression in brain astrocytes. Herein, we evaluate the effects of H. zeylanica extracts on BK-induced MMP-9 expression in brain astrocytes and its influencing mechanism. The results showed that H. zeylanica extracts, including E0, E1, and E2 significantly reduce MMP-9 induced by BK in brain astrocytes (RBA-1 cells). These H. zeylanica extracts can inhibit BK-stimulated phosphorylation of c-Src, Pyk2, and PKC(α/δ). Moreover, BK-stimulated NADPH oxidase (Nox)-derived reactive oxygen species (ROS) generation has also been attenuated by pretreatment with these extracts, suggesting that the H. zeylanica extracts have an antioxidative activity. We further demonstrated that the H. zeylanica extracts blocked activation of MAPKs (e.g., ERK1/2 and p38 MAPK) by BK. These data indicated that the H. zeylanica extracts may be has anti-inflammatory activity by reducing BK-induced ROS-dependent MMP-9 expression via these related pathways in brain astrocytes.

Cytotoxic effects of oosporein isolated from endophytic fungus Cochliobolus kusanoi

In the present study, oosporein, a fungal toxic secondary metabolite known to be a toxic agent causing chronic disorders in animals, was isolated from fungus Cochliobolus kusanoi of Nerium oleander L. Toxic effects of oosporein and the possible mechanisms of cytotoxicity as well as the role of oxidative stress in cytotoxicity to Madin-Darby canine kidney kidney cells and RAW 264.7 splene cells were evaluated in vitro. Also to know the possible in vivo toxic effects of oosporein on kidney and spleen, Balb/C mouse were treated with different concentrations of oosporein ranging from 20 to 200 μM). After 24 h of exposure histopathological observations were made to know the effects of oosporein on target organs. Oosporein induced elevated levels of reactive oxygen species (ROS) generation and high levels of malondialdehyde, loss of mitochondrial membrane potential, induced glutathione hydroxylase (GSH) production was observed in a dose depended manner. Effects oosporein on chromosomal DNA damage was assessed by Comet assay, and increase in DNA damage were observed in both the studied cell lines by increasing the oosporein concentration. Further, oosporein treatment to studied cell lines indicated significant suppression of oxidative stress related gene (Superoxide dismutase1 and Catalase ) expression, and increased levels of mRNA expression in apoptosis or oxidative stress inducing genes HSP70, Caspase3, Caspase6, and Caspase9 as measured by quantitative real time-PCR assay. Histopathological examination of oosporein treated mouse kidney and splenocytes further revealed that, oosporein treated target mouse tissues were significantly damaged with that of untreated sam control mice and these effects were in directly proportional to the the toxin dose. Results of the present study reveals that, ROS is the principle event prompting increased oosporein toxicity in studied in vivio and in vitro animal models. The high previlance of these fungi in temperate climates further warrants the need of safe food grain storage and processing practices to control the toxic effects of oosporein to humans and live stock.

Pterostilbene mediates neuroprotection against oxidative toxicity via oestrogen receptor α signalling pathways

Objectives

Accumulating evidence indicated protective role of phytoestrogens against neuronal damage induced by various insults, such as amyloid beta, oxygen deprivation and mitochondrial toxins. Hydrogen peroxide (H2O2) influences the mitochondrial membrane potential, which eventually results in cell apoptosis. In this study, we investigated the effects and possible mechanisms of a phytoestrogen, pterostilbene (PTER), in cell apoptosis induced by H2O2 in human neuronal SH-SY5Y cells. We also analysed the involvement of oestrogen receptors, oestrogen receptor-α and -β (ER-α and ER-β) in the protective role of PTER.

Methods

The effects of PTER on H2O2-stimulated cell were examined using MTT and FACS analysis. The signal pathways and estrogen receptors involved in PTER's effects were investigated using MTT and Western blot analysis.

Key findings

The results showed that H2O2 treatment significantly reduced cell viability in SY5Y cells, which was protected by PTER treatment. We also found that H2O2 inhibited the PI3K/AKT and MAPK/ERK signalling pathways, whereas PTER treatment restored these signalling pathways. We also found that the PTER effect could be largely blocked by an ER-α antagonist, 3-Bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP), but not by an ER-β antagonist, 4-[2-Phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a] pyrimidin-3-yl]phenol (PHTPP), suggesting that ER-α is a major player in the neuroprotective activity of PTER.

Conclusion

Our study thus demonstrates that PTER is an effective neuroprotective agent presumably through ER-α-mediated signalling pathways.

Neuroprotective effects of Cyperus rotundus on SIN-1 induced nitric oxide generation and protein nitration: ameliorative effect against apoptosis mediated neuronal cell damage

Nitrosylation of tyrosine (3-nitro tyrosine, 3-NT) has been implicated in the pathophysiology of various disorders particularly neurodegenerative conditions and aging. Cyperus rotundus rhizome is being used as a traditional folk medicine to alleviate a variety of disorders including neuronal stress. The herb has recently found applications in food and confectionary industries also. In current study, we have explored the protective effects of C. rotundus rhizome extract (CRE) through its oxido-nitrosative and anti apoptotic mechanism to attenuate peroxynitrite (ONOO(-)) induced neurotoxicity using human neuroblastoma SH-SY5Y cells. Our results elucidate that pre-treatment of neurons with CRE ameliorates the mitochondrial and plasma membrane damage induced by 500 μM SIN-1 to 80% and 24% as evidenced by MTT and LDH assays. CRE inhibited NO generation by downregulating i-NOS expression. SIN-1 induced depletion of antioxidant enzyme status was also replenished by CRE which was confirmed by immunoblot analysis of SOD and CAT. The CRE pre-treatment efficiently potentiated the SIN-1 induced apoptotic biomarkers such as bcl-2 and caspase-3 which orchestrate the proteolytic damage of the cell. The ONOO(-) induced damage to cellular, nuclear and mitochondrial integrity was also restored by CRE. Furthermore, CRE pre-treatment also regulated the 3-NT formation which shows the potential of plant extract against tyrosine nitration. Taken together, our findings suggest that CRE might be developed as a preventive agent against ONOO(-) induced apoptosis.

Ugonin K promotes osteoblastic differentiation and mineralization by activation of p38 MAPK- and ERK-mediated expression of Runx2 and osterix

Ugonin K is a flavonoid isolated from the roots of Helminthostachys zeylanica, a folk medicine used to strengthen bone mass and cure bone fracture. It is of interest to determine whether ugonin K has beneficial effect on osteoblast maturation. In this study, MC3T3-E1 osteoblasts were treated with ugonin K. Cell differentiation and mineralization were identified by alkaline phosphatase (ALP) activity and Alizarin red S staining, respectively. RT-PCR and Western blot were used to analyze osteoblast-associated gene expression and signaling pathways. Our results showed that ugonin K significantly induced the increase of ALP activity, expressions of bone sialoprotein (BSP) and osteocalcin (OCN), and mineralization. The mRNA expressions of the transcription factors Runx2 and osterix were also up-regulated by ugonin K. Ugonin K increased the phosphorylated level of p38 and ERK, respectively. In the presence of SB203580, ugonin K induced expressions of Runx2 and osterix, ALP activity, BSP level and bone nodule formation were all completely inhibited, but ugonin K induced OCN expression was not affected. On the other hand, ugonin K-induced ALP activity and mineralization were mildly attenuated by PD98059, but the over-expressed Runx2, osterix, BSP and OCN also were significantly repressed by PD98059. These suggested that both p38 and ERK participate in regulating ugonin K evoked osteogenesis but p38 seemed to play a more important role. Take together, the potential anabolic effect of ugonin K on bone might act through activations of p38- and ERK-mediated Runx2 and osterix expressions to induce the synthesis of osteoids and formation of bone nodule.

Myricetin protects cells against oxidative stress-induced apoptosis via regulation of PI3K/Akt and MAPK signaling pathways

Recently, we demonstrated that myricetin exhibits cytoprotective effects against H₂O₂-induced cell damage via its antioxidant properties. In the present study, myricetin was found to inhibit H₂O₂-induced apoptosis in Chinese hamster lung fibroblast (V79-4) cells, as shown by decreased apoptotic bodies, nuclear fragmentation, sub-G₁ cell population, and disruption of mitochondrial membrane potential (Δψ_m), which are increased in H₂O₂-treated cells. Western blot data showed that in H₂O₂-treated cells, myricetin increased the level of Bcl-2, which is an anti-apoptotic factor, and decreased the levels of Bax, active caspase-9 and -3, which are pro-apoptotic factors. And myricetin inhibited release of cytochrome c from mitochondria to cytosol in H₂O₂-treated cells. Myricetin-induced survival correlated with Akt activity, and the rescue of cells by myricetin treatment against H₂O₂-induced apoptosis was inhibited by the specific PI3K (phosphoinositol-3-kinase) inhibitor. Myricetin-mediated survival also inhibited the activation of p38 mitogen activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK), which are members of MAPK. Our studies suggest that myricetin prevents oxidative stress-induced apoptosis via regulation of PI3K/Akt and MAPK signaling pathways.

Mixed monolayers of ferrocenylalkanethiol and encapsulated horseradish peroxidase for sensitive and durable electrochemical detection of hydrogen peroxide

This paper describes the construction of a mixed monolayer of ferrocenylalkanethiol and encapsulated horseradish peroxidase (HRP) at a gold electrode for amperometric detection of H(2)O(2) at trace levels. By tuning the alkanethiol chain lengths that tether the HRP enzyme and the ferrocenylalkanethiol (FcC(11)SH) mediator, facile electron transfer between FcC(11)SH and HRP can be achieved. Unlike most HRP-based electrochemical sensors, which rely on HRP-facilitated H(2)O(2) reduction (to H(2)O), the electrocatalytic current is resulted from an HRP-catalyzed oxidation reaction of H(2)O(2) (to O(2)). Upon optimizing other experimental conditions (surface coverage ratio, pH, and flow rate), the electrocatalytic reaction proceeding at the electrode was used to attain a low amperometric detection level (0.64 nM) and a dynamic range spanning over 3 orders of magnitude. Not only does the thin hydrophilic porous HRP capsule allow facile electron transfer, it also enables H(2)O(2) to permeate. More significantly, the enzymatic activity of the encapsulated HRP is retained for a considerably longer period (>3 weeks) than naked HRP molecules attached to an electrode or those wired to a redox polymer thin film. By comparing to electrodes modified with denatured HRP that are subsequently encapsulated or embedded in a poly-L-lysine matrix, it is concluded that the encapsulation has significantly preserved the native structure of HRP and therefore its enzymatic activity. The electrode covered with FcC(11)SH and encapsulated HRP is shown to be capable of rapidly and reproducibly detecting H(2)O(2) present in complex sample media.