The cytoprotective effect of <Emphasis Type="Italic">Rumex Aquaticus Herba</Emphasis> extract against hydrogen peroxide-induced oxidative stress in AGS cells

The Rumex Aquaticus Herba extract containing quercetin-3-β-D-glucuronopyranoside (ECQ) has been reported to exhibit various pharmacological activities, including anti-inflammatory and anti-oxidative effects. This plant has been traditionally used for the treatment of diarrhea, disinfestation, edema and jaundice, and as an antipyretic drug. The aim of the present study was to investigate the ability of ECQ to protect against oxidative damage and to determine its signaling mechanism in AGS cells. The protein expressions of heme oxygenase-1 (HO-1) and nuclear factor-erythroid 2 related factor 2 (Nrf2) were measured by Western blots. Cell viability was measured by MTT assay. Intracellular reactive oxygen species (ROS) levels were measured using 2′,7′-dichlorofluorescein diacetate. Glutathione peroxidase levels were measured using kits. The protein expressions of HO-1 and its upstream mediator, Nrf2, increased after ECQ treatment. The HO-1 inhibitor, ZnPP, repressed the protective effect of ECQ on H₂O₂-induced cell damage. We found that LY294002, a specific PI3 K/Akt inhibitor, suppressed ECQ-induced HO-1 expression. ECQ significantly attenuated H₂O₂-induced cytotoxicity and ROS generation. Also, ECQ enhanced the antioxidant enzyme activities of glutathione peroxidase. These results suggest that ECQ exerts a cytoprotective effect against H₂O₂-induced oxidative stress by upregulation of Nrf2/HO-1 via the PI3 K/Akt pathway.     

Kurarinone attenuates hydrogen peroxide-induced oxidative stress and apoptosis through activating the PI3K/Akt signaling by upregulating IGF1 expression in human ovarian granulosa cells

Dysregulated follicular development may lead to follicular atresia, and this is associated with oxidative stress in granulosa cells. Kurarinone is a natural compound possessing multiple activities, including antioxidative ability. However, the role of kurarinone in granulosa cell damage during follicular atresia remains unknown. Human ovarian granulosa KGN cells were treated with hydrogen peroxide (H₂O₂) to induce cellular damage. Cytotoxicity was investigated by lactate dehydrogenase (LDH) release assay. Oxidative stress was evaluated by detection of reactive oxygen species (ROS) generation and oxidative biomarker levels. Cell apoptosis was evaluated by flow cytometry, a Cell Death Detection ELISA Kit, and a Caspase-3 Assay Kit. The downstream target and related signaling pathway were analyzed by western blotting. Kurarinone attenuated H₂O₂-induced LDH release in KGN cells. Kurarinone relieved H₂O₂-induced increase in ROS generation and malondialdehyde level as well as decrease in superoxide dismutase-1 activity and heme oxygenase 1 and NAD(P)H quinone dehydrogenase 1 mRNA levels. Kurarinone inhibited H₂O₂-induced apoptosis in KGN cells. Kurarinone targeted insulin-like growth factor 1 (IGF1) and upregulated IGF1 expression to activate the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling. IGF1 silencing attenuated the suppressive effects of kurarinone on H₂O₂-induced oxidative stress and apoptosis in KGN cells. In conclusion, kurarinone attenuates H₂O₂-induced oxidative stress and apoptosis in KGN cells through activating the PI3K/Akt signaling by upregulating IGF1 expression, indicating the therapeutic potential of kurarinone in follicular atresia.     

YS 51, 1-(beta-naphtylmethyl)-6,7-dihydroxy-1,2,3,4,-tetrahydroisoquinoline, protects endothelial cells against hydrogen peroxide-induced injury via carbon monoxide derived from heme oxygenase-1

Oxidative stress plays an important role in the pathophysiology of several vascular diseases such as atherosclerosis, and great attention has been placed on the protective role of heme oxygenase-1 (HO-1) for vasculature against oxidant-induced injury. We tested whether the protective effects of YS 51, 1-(β-naphtyl-methyl)-6,7-dihydroxy-1,2,3,4,-tetrahydroisoquinoline, against hydrogen peroxide (H₂O₂)-induced cell injury is associated with HO-1 activity in bovine aortic endothelial cells (BAEC). YS 51 increased HO-1 expression and activity in concentration-dependent manners (10-100 μM) and time-dependent manners (1, 3, 6, 18 h), which were correlated well with its protective effect against H₂O₂-induced injury. Zinc protoporphyrin IX (ZnPP IX), a HO inhibitor, significantly inhibited the effect of YS 51 (50 μM). In contrast, [Ru(CO)₃(Cl)₂]₂ (CORM-2, a CO releasing molecule) but not bilirubin protected against H₂O₂-induced injury. Oxyhemoglobin (HbO₂) used as a CO scavenger significantly inhibited the protective effect of both YS 51 and CORM-2. Furthermore, both YS 51 and CORM-2 significantly reduced H₂O₂-induced intracellular reactive oxygen species (ROS) production; however, this was counteracted by ZnPP IX, HbO₂ and deferoxamine. We found evidence for the involvement of PI3/Akt kinase and ERK1/2 pathways in HO-1 induction by YS-51. Taken together, we conclude that CO is, at least, responsible for the YS 51-mediated protective action of endothelial cells against oxidant stress via HO-1 gene induction, involving the activation of the PI3/Akt and ERK1/2 kinase pathways. Thus, YS 51 may be useful in oxidative stress-induced vascular disorders.     

淫羊藿苷对H2O2诱导的软骨细胞氧化损伤的保护作用及其机制

目的 探究淫羊藿苷（icariin，ICA）对H₂O₂诱导的软骨细胞氧化损伤的保护作用及相关机制。方法 分离SD新生大鼠软骨细胞，随机分为对照组、H₂O₂模型组、ICA低剂量组、ICA中剂量组、ICA高剂量组；采用CCK8法检测各组细胞增殖能力的变化；采用ELISA试剂盒检测各组细胞中活性氧（reactive oxygen，ROS）、超氧化物歧化酶（superoxide dismutase，SOD）、丙二醛（malondialdehyde，MDA）、过氧化氢酶（catalase，CAT）以及谷胱甘肽过氧化物酶（glutathione peroxidase，GSH-Px）的表达情况；流式细胞术检测各组细胞周期情况，并计算增殖指数（proliferation index，PI）；Hoechst染色观察各组细胞核凋亡情况；分别采用荧光定量PCR （qRT-PCR）和Western blotting检测凋亡相关因子及Nrf2/HO-1通路的表达情况。结果 与对照组相比，H₂O₂模型组细胞增殖能力降低，ROS、MDA含量升高，SOD、CAT及GSH-Px含量下降，细胞凋亡情况加重；经ICA干预后，软骨细胞的增殖能力上升，ROS、MDA含量下降，SOD、CAT及GSH-Px含量增加，并且ICA能够有效抑制软骨细胞凋亡，上调Nrf2和HO-1蛋白的表达。结论 ICA对H₂O₂诱导的软骨细胞氧化损伤具有保护作用，能够抑制软骨细胞凋亡，其机制跟Nrf2/HO-1信号通路有关。     

Honokiol inhibits H(2)O(2)-induced apoptosis in human lens epithelial cells via inhibition of the mitogen-activated protein kinase and Akt pathways

Oxidative stress-induced apoptosis in lens epithelial cells plays an important role in cataract formation, and its prevention may be of therapeutic interest. This study was performed to investigate the protective effect and mechanisms of honokiol on H₂O₂-induced apoptosis in human lens epithelial (HLE) cells. HLE cells (SRA01-04) were pretreated with honokiol at concentrations of 5 μM, 10 μM and 20 μM before 50 μM H₂O₂ treatment. The results demonstrated that pretreatment of honokiol inhibited the activation of caspase-3 and caspase-9 and downregulated the expression of Bcl-2. Mechanistically, honokiol suppressed H₂O₂-induced phosphorylation of ERK1/2, p38 mitogen-activated protein kinase (MAPK), JNK and Akt. Honokiol also inhibited H₂O₂-induced nuclear factor-κB (NF-κB)/p65 phosphorylation and translocation in HLE cells. These results demonstrate that honokiol suppresses H₂O₂-induced HLE cell apoptosis via interference with the MAPKs, Akt and NF-κB signaling, suggesting that honokiol might have a potential effect against cataract formation.     

DL0410 attenuates oxidative stress and neuroinflammation via BDNF/TrkB/ERK/CREB and Nrf2/HO-1 activation

Oxidative stress and neuroinflammation have been deeply associated with Alzheimer’s disease. DL0410 is a novel acetylcholinesterase inhibitor with potential anti-oxidative effects in AD-related animal models, while the specific mechanism has not been fully clarified. In this study, DL0410 was predicted to be related to the modification of cell apoptosis, oxidation-reduction process, inflammatory response and ERK1/ERK2 cascade by in silico target fishing and GO enrichment analysis. Then the possible protective effects of DL0410 were evaluated by hydrogen peroxide (H₂O₂)-induced oxidative stress model and lipopolysaccharides (LPS)-induced neuroinflammation model H₂O₂ decreased the viability of SH-SY5Y cells, induced malondialdehyde (MDA) accumulation, mitochondrial membrane potential (Δψm) loss and cell apoptosis, which could be reversed by DL0410 dose-dependently, indicating that DL0410 protected SH-SY5Y cells against H₂O₂-mediated oxidative stress. Western blot analysis showed that DL0410 increased the H₂O₂-triggered down-regulated TrkB, ERK and CREB phosphorylation and the expression of BDNF. In addition, TrkB inhibitor ANA-12, ERK inhibitor SCH772984 and CREB inhibitor 666-15 eliminated the inhibition of DL0410 on MDA accumulation and Δψm loss. Furthermore, DL0410 attenuates inflammatory responses and ROS production in LPS-treated BV2 cells, which is responsible for Nrf2 and HO-1 up-regulation. The present study demonstrates that DL0410 is a potential activator of the BDNF/TrkB/ERK/CREB and Nrf2/HO-1 pathway and may be a potential candidate for regulating oxidative stress and neuroinflammatory response in the brain. Together, the results showed that DL0410 is a promising drug candidate for treating AD and possibly other nervous system diseases associated with oxidative stress and neuroinflammation.     

The neuroprotective effects of Lonicera japonica THUNB. against hydrogen peroxide-induced apoptosis via phosphorylation of MAPKs and PI3K/Akt in SH-SY5Y cells

We investigated the neuroprotective effects of Lonicera japonica THUNB. (Caprifoliaceae) (LJ) extract against hydrogen peroxide (H₂O₂), a toxin created by oxidative stress and implicated in neurodegenerative diseases, in human SH-SY5Y neuroblastoma cells. We examined the effects of LJ against H₂O₂-induced cytotoxicity, apoptosis, the production of reactive oxygen species (ROS), the proteolysis of cleaved poly-ADP-ribose polymerase (PARP), and the expression of Bcl-2, Bcl-xL, and cleaved caspase-3. Moreover, we attempted to determine whether LJ suppressed the phosphorylation of Akt, c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and extracellular signal-regulated kinase 1/2 (ERK 1/2). We found that LJ improved cell viability, inhibited cytotoxicity and apoptosis, and attenuated elevations in ROS and nuclear condensation. In addition, LJ showed radical scavenging ability in 2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-(3-ethyl-benzthiazoline-6-sulfonic acid) (ABTS) assays. Western blot data revealed that LJ inhibited H₂O₂-induced up- and down-regulation of cleaved PARP, cleaved caspase-3, Bcl-2, and Bcl-xL. Furthermore, LJ significantly attenuated the H₂O₂-induced phosphorylation of Akt, JNK, p38 MAPK, and ERK1/2. These results demonstrate that LJ possesses potent neuroprotective activity. Its potential to treat neurodegenerative diseases warrants further research.     

The role of NAD-dependent isocitrate dehydrogenase 3 subunit α in AFB1 induced liver lesion

Aflatoxin B₁ (AFB₁) is a potent hepatocarcinogen that causes carcinogenesis in many animal species. In previous study, we found that isocitrate dehydrogenase 3α subunit (IDH3α) was upregulated in AFB₁-induced carcinogenesis process. In this study, the sequences of IDH3α from various species were compared and the protein expression levels in different organs were examined, and the results showed that IDH3α was a widely distributed protein and shared highly conserved sequence in various species. In the same time, IDH3α was demonstrated to accumulate in a dose-dependent manner induced by AFB1 in cells, and was also up-regulated in the process of AFB₁-induced liver lesion. Similar results were observed when H₂O₂ was used to replace AFB₁. Over-expression of IDH3α increased the phosphorylation level of Akt (Protein kinase B) and neutralized the cellular toxicity induced by AFB1 or H₂O₂ and apoptosis induced by AFB₁, while the reduced expression of IDH3α by siRNA decreased the phosphorylation, indicating that IDH3α played important roles in oxidative stress-induced PI3K/Akt pathway. Overall, the results suggested that AFB₁ treatment could increase the expression of IDH3α, and the activated PI3K/Akt pathway by IDH3α eventually neutralized the apoptosis induced by AFB₁.     

Icaritin activates Nrf2/Keap1 signaling to protect neuronal cells from oxidative stress

Our earlier study indicated that icaritin (ICT) protected mice from cerebral ischemic injury by inhibiting oxidative stress, and this study aimed to investigate its mechanism using a H₂O₂‐treated SH‐SY5Y cells model. Cell viability was assessed by cell counting kit 8 (CCK‐8). Oxidative stress parameters were detected by flow cytometry, and signaling pathways were analyzed by immunoblotting. We found that ICT alleviated apoptosis and intracellular and mitochondrial reactive oxygen species (ROS) levels, decreased the expressions of Bax and cleaved caspase‐3, and increased the expressions of Bcl‐2 compared to H₂O₂ group. ICT increased mitochondrial membrane potential (ΔΨm) and blocked the opening of mitochondrial membrane permeability transporter (MPT), and increased the activity of glutathione peroxidase (GSH‐px), catalase (CAT), and superoxide dismutase (SOD), meanwhile, decreased the activity of malondialdehyde (MDA) compared to H₂O₂ group. Further investigation revealed that ICT significantly up‐regulated the expressions of nuclear factor erythroid 2‐related factor 2 (Nrf2), heme oxygenase 1 (HO‐1) and NAD(P)H‐quinone oxidoreductase 1 (NQO‐1). The anti‐apoptosis and antioxidative effects of ICT were blocked bay ML385, a Nrf2/Keap1 signaling pathway inhibitor. These results indicate that ICT can play a neuroprotective role against oxidative stress injury by activating Nrf2/Keap1 signaling pathway.     

Cardioprotective effect of KR-33889, a novel PARP inhibitor,against oxidative stress-induced apoptosis in H9c2 cells and isolated rat hearts

Oxidative stress plays a critical role in cardiac injury during ischemia/reperfusion (I/R). Despite a potent cardioprotective activity of KR-33889, a novel poly (ADP-ribose) polymerase inhibitor, its underlying mechanism remains unresolved. This study was designed to investigate the protective effects of KR-33889 against oxidative stress-induced apoptosis in rat cardiomyocytes H9c2 cells and isolated rat hearts. H₂O₂ caused severe injury to H9c2 cells, mainly due to apoptosis, as revealed by TUNEL assay. However, KR-33889 pretreatment significantly attenuated H₂O₂-induced apoptosis of H9c2 cells, which was accompanied by decrease in expression of both cleaved caspase-3 and Bax and increase in Bcl-2 expression and the ratio of Bcl-2/Bax. KR-33889 also significantly enhanced the expression of anti-oxidant enzymes including heme oxygenase-1, Cu/Zn-superoxide dismutase (SOD), Mn-SOD, and catalase, thereby inhibiting production of intracellular ROS. Furthermore, KR-33889 reversed H₂O₂-induced decrease in phosphorylation of Akt, GSK-3β, ERK1/2, p38 MAPK, and SAPK/JNK during most H₂O₂ exposure time. In globally ischemic rat hearts, KR-33889 inhibited both I/R-induced decrease in cardiac contractility and apoptosis by increasing Bcl-2, decreasing both cleaved caspase-3 and Bax expression, and enhancing expression of anti-oxidant enzymes. Taken together, these results suggest that KR-33889 may have therapeutic potential to prevent I/R-induced heart injury in ischemic heart diseases mainly by reducing oxidative stress-mediated myocardial apoptosis.     

3′,4′,7-Trihydroxyflavone prevents apoptotic cell death in neuronal cells from hydrogen peroxide-induced oxidative stress

In this study, we investigated the mechanisms of 3′,4′,7-trihydroxyflavone (THF) protection of neuronal cells from neuronal cell death induced by the oxidative stress-related neurotoxin hydrogen peroxide (H₂O₂). Pretreatment with THF significantly elevated cell viability, reduced H₂O₂-induced lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) production, glutathione (GSH) content, superoxide dismutase (SOD) activity, catalase (CAT) activity, and mitochondria membrane potential (MMP) loss. Western blot data demonstrated that THF inhibited the H₂O₂-induced up- or down-regulation of cleaved caspase-3, cleaved caspase-9, cleaved poly-ADP-ribose polymerase (PARP), Bax, Bcl-2, and Bcl-xL, and attenuated the H₂O₂-induced release of cytochrome c from the mitochondria to the cytosol. In addition, pretreatment with THF attenuated H₂O₂-induced rapid and significant phosphorylation of c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinases (PI3K)/Akt. THF also inhibited nuclear factor-κB (NF-κB) translocation to the nucleus induced by H₂O₂, down-stream of H₂O₂-induced phosphorylation of MAPKs and PI3K/Akt. These data provide the first evidence that THF protects neuronal cells against H₂O₂-induced oxidative stress, possibly through ROS reduction, mitochondria protection, and NF-κB modulation via MAPKs and PI3K/Akt pathways. The neuroprotective effects of THF make it a promising candidate as a therapeutic agent for neurodegenerative diseases.     

Butein protects human dental pulp cells from hydrogen peroxide-induced oxidative toxicity via Nrf2 pathway-dependent heme oxygenase-1 expressions

Rhus verniciflua Stokes is a plant that is native to East Asian countries, such as Korea, China, and Japan. Butein, a plant polyphenol, is one of the major active components of R. verniciflua. Reactive oxygen species (ROS), produced via dental adhesive bleaching agents and pulpal disease, can cause oxidative stress. Here, we found that butein possesses cytoprotective effects on hydrogen peroxide (H₂O₂)-induced dental cell death. H₂O₂ is a representative ROS and causes cell death through necrosis in human dental pulp (HDP) cells. H₂O₂-induced cytotoxicity and production of ROS were blocked in the presence of butein, and these effects were dose dependent. Butein also increased heme oxygenase-1 (HO-1) protein expression and HO activity. In addition, butein-dependent HO-1 expression was required for the inhibition of H₂O₂-induced cell death and ROS generation. Furthermore, butein treatment caused nuclear accumulation of nuclear factor-E2-related factor 2 (Nrf2) and increased the promoter activity of antioxidant response elements (AREs). Treatment of HDP cells with a c-Jun NH2-terminal kinase (JNK) inhibitor also reduced butein-induced HO-1 expression, and butein treatment led to increased JNK phosphorylation. These results indicate that butein may be used to prevent functional dental cell death and thus may be useful as a pulpal disease agent.     

Icaritin inhibits oxidative stress in murine astrocytes by binding to Orai1 to block store-operated calcium channel

Previous study has shown that icaritin (ICT) has meaningful protective effect on cerebral ischemic stroke, and this study aimed to investigate its mechanism from the aspect of protecting astrocytes from oxidative stress. Murine primary astrocytes were pretreated by ICT and exposed to H₂O₂ to induce oxidative stress. The results indicated that ICT inhibited H₂O₂-induced astrocytes apoptosis, decreased Bax and cleaved caspase-3, and increased Bcl-2. In addition, ICT inhibited H₂O₂-induced oxidative stress, increased mitochondrial membrane potential (ΔΨ_m), and maintained mitochondrial morphology. ICT decreased the synthesis of malondialdehyde and increased the activity of glutathione peroxidase, catalase, and superoxide dismutase. Moreover, ICT suppressed the transient and resting intracellular Ca²⁺ overload. Further investigation revealed that ICT could target the combination with Orai1 to block store-operated calcium channel induced by H₂O₂. However, ICT did not enhance the protective effect of RO2959, a selective blocker of Orai1. These results indicate that ICT can play a neuroprotective role against oxidative stress injury by binding to Orai1 to block SOCC.     

Ferulic acid inhibits H2O2-induced oxidative stress and inflammation in rat vascular smooth muscle cells via inhibition of the NADPH oxidase and NF-κB pathway

Ferulic acid (FA) is a dietary phenolic acid and has a wide range of therapeutic effects, including anti-aging, antitumor activity and antihypertensive effects. The aim of present study was to evaluate the inhibitory effects of FA on cell inflammation and oxidative stress against hydrogen peroxide (H₂O₂)-induced injury in rat vascular smooth muscle cells (VSMCs) in vitro. VSMCs were pretreated with FA 2 h before H₂O₂ incubation. The results suggested that FA inhibited H₂O₂-induced cell injury by reducing the MDA and increasing the SOD activity and GSH content. In rat VSMCs exposed to H₂O₂, FA increased the cell viability and restored the mitochondrial membrane depolarization. The level of ROS generation was reduced by pretreatment with FA through inhibiting the expression of NADPH oxidase and down-regulating MAPK and AKT pathways. We found that H₂O₂ stimulated the production of IL-6, IL-1β, TNF-α and NO, which could be reduced by pretreatment with FA through inhibiting the p-NF-κB as well as the iNOS expression. In conclusion, our results show that FA may serve as a novel drug in the treatment of these pathologies by inhibiting NADPH oxidase and NF-κB and subsequently decreasing VSMC oxidative stress and inflammation. These suggest that the inhibitory effect of FA on VSMC inflammation and oxidative stress is partially attributed to depressing NADPH and NF-κB expressions in VSMCs, decreasing the ROS production and reducing apoptosis of VSMCs.     

EGFR-dependent ERK activation triggers hydrogen peroxide-induced apoptosis in OK renal epithelial cells

Oxidative stress induces activation of extracellular signal-regulated kinase (ERK), a member of the mitogen-activated protein kinase families. However, it is unclear in renal epithelial cells whether the ERK activation is involved in cell survival or cell death in H₂O₂-treated cells. The present study was undertaken to determine the role of the ERK activation in H₂O₂-induced apoptosis of renal epithelial cells using opossum kidney (OK) cells, an established proximal tubular epithelial cell line. H₂O₂ resulted in a time- and dose-dependent apoptosis of OK cells. H₂O₂ treatment caused marked sustained activation of ERK. The ERK activation was prevented by PD98059 and U0126, inhibitors of ERK1/2 upstream kinase MEK1/2. Apoptosis caused by H₂O₂ was prevented by U0126. Transient transfection with constitutive active MEK1 increased the H₂O₂-induced apoptosis, whereas transfection with dominant-negative mutants of MEK1 decreased the apoptosis. H₂O₂ produced hyperpolarization of mitochondrial membrane potential and activation of caspases-3. H₂O₂-induced ERK activation was inhibited by the Src family selective inhibitor PP2 and the epidermal growth factor receptor inhibitor AG1478. The presence of AG1478, but not PP2, prevented H₂O₂-induced cell death. Taken together, our findings suggest that the ERK activation mediated by epidermal growth factor receptor plays an active role in inducing H₂O₂-induced apoptosis of OK cells and functions upstream of mitochondria-dependent pathway to initiate the apoptotic signal.     

Safflor yellow B suppresses pheochromocytoma cell (PC12) injury induced by oxidative stress via antioxidant systemand Bcl-2 /Bax pathway

Our previous study demonstrates that SYB produces a neuroprotective effect in vivo. In the present study, we investigated the protective effect of safflor yellow B (SYB) on the acute oxidative injury induced by H₂O₂ and mechanisms in PC12 cells. H₂O₂ was used to mimic in vitro model of the oxidative injury and to induce apoptosis in PC12 cells. The cells were pretreated with the different concentrations of SYB. The cell viability, lactate dehydrogenase (LDH) release, malondialdehyde (MDA), and superoxide anion levels, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were measured. Caspase 3 activity, Bcl-2 and Bax expressions were also observed. The results showed that exposure of the cells to H₂O₂ significantly decreased the cell viability, SOD and GSH-Px activities and Bcl-2 expression, and increased LDH release, superoxide anion and MDA generations, caspase 3 activity and Bax expressions. Pretreatment of the cells with SYB was able to remarkably antagonize the H₂O₂-induced changes in dose-dependent way. These suggest that SYB is able to protect PC12 cells from H₂O₂-induced injury and apoptosis via antioxidant and anti-apoptotic mechanisms.     

Protective effects of protopine on hydrogen peroxide-induced oxidative injury of PC12 cells via Ca(2+) antagonism and antioxidant mechanisms

Calcium and lipid peroxidation play important roles in oxidative stress-induced cellular injury and apoptosis, which ultimately cause cell death. In this study we examined whether protopine had a neuroprotection against H₂O₂-induced injury in PC12 cells. Pretreatment of PC12 cells with protopine improved the cell viability, enhanced activities of superoxide dismutase, glutathione peroxidase and catalase, and decreased malondialdehyde level in the H₂O₂ injured cells. Protopine also reversed the increased intracellular Ca²⁺ concentration and the reduced mitochondrial membrane potential caused by H₂O₂ in the cells. Furthermore, protopine was able to inhibit caspase-3 expression and cell apoptosis induced by H₂O₂. In summary, this study demonstrates that protopine is able to relieve H₂O₂-induced oxidative stress and apoptosis in PC12 cells, at least in part, by Ca²⁺ antagonism and antioxidant mechanisms.     

Northeast Portuguese propolis protects against staurosporine and hydrogen peroxide-induced neurotoxicity in primary cortical neurons

The present work describes the protective effects of the crude Northeast Portuguese propolis enriched phenolic extract against staurosporine (STS) and hydrogen peroxide (H₂O₂)-induced neurotoxicity. These two stress inducers act through various pathways, including the production of reactive oxygen species (ROS) and the induction of apoptosis through caspases activation. STS (25 and 50 nM) and H₂O₂ (100 μM) increased intracellular ROS and diminished cellular reducing ability in cultured cortical neurons, under conditions unrelated with massive loss of plasma membrane integrity, suggesting decreased neuronal function. Moreover, 25 nM STS and 100 μM H₂O₂ increased caspase-3 activity by about 2.8- and 4.6-fold, respectively. Pre-treatment of cortical neurons with the ethanolic extract of propolis (EEP) in the range of 0.01–1 μg/ml showed no protective effect on cell reducing capacity, but decreased H₂O₂-stimulated increment in ROS production by about 17%. In addition, the EEP attenuated STS- or H₂O₂-induced activation of caspase-3 by 23–39%. Overall, the results show moderate protective effects induced by Northeast Portuguese EEP in cortical neurons subjected to stress stimuli.     

Wogonin inhibits H2O2-induced angiogenesis via suppressing PI3K/Akt/NF-κB signaling pathway

Wogonin, a natural monoflavonoid extracted from Scutellariae radix, has been reported for its ability of inhibiting tumor angiogenesis. In this study, we assessed the effect of wogonin on angiogenesis induced by low level of H₂O₂ (10 μM) in human umbilical vein endothelial cells (HUVECs). Wogonin suppressed H₂O₂-induced migration and tube formation of HUVECs as well as microvessel sprouting from rat aortic rings in vitro. Meanwhile, wogonin suppressed vessel growth in chicken chorioallantoic membrane (CAM) model in vivo. Mechanistic studies showed that wogonin suppressed H₂O₂-activated PI3K/Akt pathway and reduced the expression of vascular endothelial growth factor (VEGF) up-regulated by H₂O₂ in both protein and mRNA levels. In addition, wogonin also inhibited nuclear translocation of NF-κB, and decreased the binding ability of NF-κB with exogenous consensus DNA oligonucleotide. Then we further investigated the effect of wogonin on over-activated PI3K/Akt pathway by insulin-like growth factor-1 (IGF-1) and H₂O₂. We found that wogonin suppressed phosphorylation of Akt, up-regulation of VEGF and angiogenesis in vitro which was further induced by IGF-1 and H₂O₂. Moreover, in NF-κB overexpressed HUVECs, wogonin could also reduce the expression of VEGF and inhibited the migration and tube formation. Taken together, these results suggested that wogonin was potential in inhibiting H₂O₂-induced angiogenesis in vitro and in vivo via suppressing PI3K/Akt pathway and NF-κB signaling.