Oxyresveratrol protects human lens epithelial cells against hydrogen peroxide-induced oxidative stress and apoptosis by activation of Akt/HO-1 pathway

Oxidative stress induced by hydrogen peroxide (H₂O₂) triggers human lens epithelial cell (HLEC) apoptosis and initiates cataract formation. Oxyresveratrol (Oxy) was reported to possess antioxidant and free radical scavenging activities. Herein, we investigated the effects of Oxy on H₂O₂-induced oxidative stress and apoptosis in HLECs and the associated mechanisms. Cell viability was detected by MTT assay. The oxidative damage was assessed by measuring the activities of superoxide dismutases-1 (SOD-1), catalase (CAT), glutathione reductase (GSH), and malondialdehyde (MDA). Apoptosis was analyzed by flow cytometry analysis. The changed expressions of heme oxygenase-1 (HO-1) and protein kinase B (Akt) pathways were evaluated by qRT-PCR and western blot. We found that exposure to H₂O₂ dose-dependently reduced cell viability, and induced oxidative stress and apoptosis in HLECs, which were reversed by pretreatment with Oxy. Oxy increased p-Akt and HO-1 expressions in H₂O₂-stimulated HLECs. Akt and HO-1 expressions form a regulatory axis and Oxy activated the Akt/HO-1 pathway in H₂O₂-stimulated HLECs. Inhibition of the Akt/HO-1 pathway by LY294002 or ZnPP attenuated the effects of Oxy on oxidative stress and apoptosis in H₂O₂-stimulated HLECs. In conclusion, Oxy protected H₂O₂-induced oxidative stress and apoptosis through activating the Akt/HO-1 pathway, suggesting the protective effect of Oxy against H₂O₂-induced cataract.     

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.     

N‐acetyl cysteine‐mediated effective attenuation of methoxychlor‐induced granulosa cell apoptosis by counteracting reactive oxygen species generation in caprine ovary

Methoxychlor (MXC), an organochloride insecticide, is a potent toxicant‐targeting female reproductive system and known to cause follicular atresia by inducing apoptosis within granulosa cells. Oxidative stress plays a pivotal role in apoptosis; thus, this study focuses on the ameliorative action of N‐acetyl cysteine (NAC) on MXC‐induced oxidative stress and apoptosis within granulosa cell of caprine ovary. Classic histology, fluorescence assay, and biochemical parameters were employed to evaluate the effect of varied concentration of NAC (1, 5, and 10 mM) on granulosa cell apoptosis after 24, 48, and 72 h exposure duration. Histomorphological studies revealed that NAC diminished the incidence of apoptotic attributes like condensed or marginated chromatin, pyknosis, crescent‐shaped nucleus, empty cell spaces, and degenerated cellular structure along with the presence of cytoplasmic processes within granulosa cells in dose‐ and time‐dependent manner. NAC significantly downregulated the percentage of MXC‐induced granulosa cell apoptosis within healthy ovarian follicle with its increasing dose, maximum at 10 mM concentration. It also significantly (p < 0.05) upregulated the activity of antioxidant enzymes, namely catalase, superoxide dismutase, and glutathione‐s‐transferase, along with ferric reducing antioxidant power further declining lipid peroxidation in the MXC‐treated caprine ovary. The results revealed a negative correlation between apoptosis frequency and antioxidant enzymes’ activity (r _CAT = ?0.67, r _SOD = ?0.56, r _GST = ?0.31; p < 0.05) while a positive correlation was observed with lipid peroxidation (r = 0.63; p < 0.05) after NAC supplementation. Thus, NAC supplementation reduces the MXC‐generated oxidative stress that perhaps declines the ROS generating signal transduction pathway of apoptosis, thereby preventing MXC‐induced granulosa cell apoptosis and follicular atresia. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 156–166, 2017.     

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.     

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.     

Water Extract of Samultang Reduces Apoptotic Cell Death by H2O2-Induced Oxidative Injury in SK-N-MC Cells

The purpose of this study was to evaluate the effects of the water extract of Samultang (SMT), a Chinese herb, on apoptotic cell death by H₂O₂-induced oxidative stress in SK-N-MC cells. A nuclear fragmentation was observed via fluorescence imaging 12 h after exposure to 30 µM H₂O₂ and DNA laddering was detected via agarose electrophoresis gel. In addition, increases in sub-G1 phase and cleavage of the PARP protein were observed. However, treatment with SMT for 2 h prior to H₂O₂ exposure significantly reduced apoptotic cell death induced by incubation with 30 µM H₂O₂ in SK-N-MC cells. Pre-incubation with water extract of SMT for 2 h prevented the H₂O₂-induced decrease in mitochondrial transmembrane potential. SMT also attenuated the increase in caspase-3 activity and the breakdown of PARP protein caused by H₂O₂-induced oxidative stress. These results suggest that the water extract of SMT provides inhibition of apoptotic cell death against oxidative injury in SK-N-MC cells.     

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.     

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.     

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.     

Ghrelin protects H9c2 cells from hydrogen peroxide-induced apoptosis through NF-κB and mitochondria-mediated signaling

Oxidative stress is a major mechanism underlying the pathogenesis of cardiovascular disease. Herein we investigate the protective effects of ghrelin in H₂O₂-induced apoptosis of H9c2 cells, as well as the possible molecular mechanisms involved. To study apoptosis, the cells were assessed by morphologic examination, MTS assay, Annexin V–propidium iodide dual staining and TUNEL analysis. Intracellular reactive oxygen species (ROS) production and mitochondrial membrane potential were also measured. To investigate the underlying molecular mechanisms, the expression of Bcl-2, Bax, active caspase-9 and NF-κB were assessed by Western blotting, and caspase-3 activity was determined by a colorimetric activity assay kit. After stimulation with H₂O₂ for 18 h, H9c2 cells viability decreased significantly; a large fraction of cells underwent apoptosis. We observed a dose-dependent rescue of H9c2 cells from H₂O₂-induced apoptosis in the presence of different ghrelin concentrations. Preincubation with ghrelin also restored the ROS and mitochondrial membrane potential levels that had been altered by H₂O₂ treatment. Moreover, ghrelin decreased H₂O₂-induced Bax production and caspase-9 activation, and increased Bcl-2 levels. NF-κB phosphorylation was also significantly inhibited by ghrelin in H₂O₂-treated cells. Caspase-3 activation was suppressed by ghrelin in H₂O₂-treated H9c2 cells in a dose-dependent manner. In summary, ghrelin protects H9c2 cells from oxidative stress-induced apoptosis through downregulation of Bax expression, caspase-9 activation and NF-κB phosphorylation, and upregulation of Bcl-2 expression. Caspase-3 activation was also reduced in a dose-dependent manner. These data suggest that ghrelin might protect against cardiovascular disease by protecting the mitochondria.     

Angiotensin II type 1 receptor blockade suppresses H2O2-induced retinal degeneration in photoreceptor cells

Exposure to reactive oxygen species (ROS) leads to the development and progression of retinal degenerative diseases. However, the exact mechanisms are not fully understood. In this article, the role of angiotensin II type 1 receptor (AT1R) signaling in H₂O₂-induced retinal damage was examined. Mouse photoreceptor-derived 661?W cells were treated with the AT1R blockers valsartan, losartan and candesartan before exposure to H₂O₂. Cell viability, intracellular ROS level, mitochondrial membrane potential (MMP), cytochrome-c level, DNA fragmentation, caspase activity and gene expression were detected. Pre-treatment of 661?W cells with AT1R blockers significantly decreased H₂O₂-mediated toxicity and reduced the ROS level. In addition, apoptosis-related biochemical indicators showed that pre-incubation of AT1R blockers would elevate the MMP, decrease the release of cytochrome-c and formation of DNA fragmentation, and inhibit activities of caspase-3 and caspase-9 in exogenous H₂O₂-treated 661?W cells. Moreover, treatment with AT1R blockers suppressed the expression of Egr1, Fosl1 and Lox12. These results suggest that AT1R signaling mediates H₂O₂-induced apoptosis, at least partially through generating the ROS and increasing the levels of proapoptotic molecules in 661?W cells. AT1R blockade may provide a new therapeutic approach for preventing oxidative stress-induced retinal neural damage.     

Diarylheptanoid 7-(3,4 dihydroxyphenyl)-5-hydroxy-1-phenyl-(1E)-1-heptene from Curcuma comosa Roxb. protects retinal pigment epithelial cells against oxidative stress-induced cell death

Chronic exposure to oxidative stress causes damage to retinal pigment epithelial cells which may lead to the development of age-related macular degeneration, the major cause of vision loss in humans. Anti-oxidants provide a natural defense against retinal cell damage. The present study was designed to evaluate the potential anti-oxidant activity and protective effect of two diarylheptanoids isolated from a medicinal herb Curcuma comosa; 7-(3,4 dihydroxyphenyl)-5-hydroxy-1-phenyl-(1E)-1-heptene (compound A), and 1,7-diphenyl-4(E),6(E)-heptadien-3-ol (compound B) against oxidative stress (H₂O₂)-induced human retinal pigment epithelial (APRE-19) cell death. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay indicated that the anti-oxidant activity (IC₅₀) of compound A was similar to that of vitamin C. Pre-treatment of ARPE-19 cells with 20 μM compound A for 4 h afforded greater protection against the insult from 500 μM H₂O₂, compared to a similar protection period for compound B. Compound A lowered H₂O₂-induced lipid peroxidation, malondialdehyde formation and intracellular reactive oxygen species. Furthermore, compound A ameliorated the H₂O₂-induced decrease in anti-oxidant enzyme activities and subsequent apoptotic cell death in ARPE-19 cells in a dose and time-dependent manner. These results suggest that compound A protects ARPE-19 cells against oxidative stress, in part, by enhancing several anti-oxidant defense mechanisms. Therefore, compound A may have therapeutic potential for diseases associated with oxidative stress, particularly degenerative retinal diseases.     

ROS activates JNK-mediated autophagy to counteract apoptosis in mouse mesenchymal stem cells in vitro

Aim:

Transplantation of mesenchymal stem cells (MSCs) for the treatment of diabetic erectile dysfunction (ED) is hampered by apoptosis of the transplanted cells. In diabetic ED, there is increased oxidative stress and decreased NO in the corpora cavernosa, and reactive oxygen species (ROS) induce apoptosis of the transplanted cells. In this study we examined whether and how autophagy was involved in ROS-induced apoptosis of MSCs.

Methods:

Mouse C3H10 MSCs were treated with H₂O₂ to simulate the high oxidative condition in diabetic ED. Cell viability was measured using MTT assay. Apoptosis was analyzed by flow cytometry. Apoptosis- and autophagy-related proteins were detected with Western blot assays. Intracellular autophagosome accumulation was studied using transmission electron microscopy.

Results:

Treatment of MSCs with H₂O₂ (50–400 μmol/L) inhibited the cell viability in concentration- and time-dependent manners. Furthermore, H₂O₂ (300 μmol/L) induced apoptosis, as well as activated autophagy in MSCs. Pretreatment with lysosome inhibitor chloroquine (10 μmol/L) or PI3K inhibitor 3-methyladenine (5 mmol/L) significantly enhanced H₂O₂-induced cell death. Pretreatment with JNK inhibitor SP600125 (10 μmol/L) abrogated H₂O₂-induced accumulation of LC3-II, and attenuated H₂O₂-induced reduction of Bcl-2 levels in MSCs.

Conclusion:

ROS induce autophagy to counteract apoptosis in MSCs by activation of JNK. Thus, augmentation of autophagy may reduce apoptosis, prolonging MSC survival and improving MSC-based therapeutic efficacy for diabetic ED.     

Metabolism of kurarinone by human liver microsomes and its effect on cytotoxicity

Context: Kurarinone, the most abundant prenylated flavonoid in Sophora flavescens Aiton (Leguminosae), is a promising antitumor therapeutic. However, it shows significant hepatotoxicity. Furthermore, how kurarinone is metabolized in humans remains unclear.

Objective: The objective of this study is to investigate kurarinone metabolism in human liver microsomes (HLMs) and the role of metabolism in kurarinone-induced cytotoxicity.

Materials and methods: The UDP-glucuronosyltransferase isoforms (UGTs) involved in kurarinone glucuronidation were identified using chemical inhibitors (100–1000?µM phenylbutazone; 10–100?µM β-estradiol; 10–100?µM 1-naphthol; 10–500?µM propofol; and 100–1000?µM fluconazole) and recombinant human UGTs. Kurarinone (2–500?µM) was incubated with HLMs and UGTs (0.5?mg/mL) for 15?min to determine enzyme kinetic parameters. The IC₅₀ value of kurarinone (10–200?µM) was evaluated in a HLMs/3T3 cell co-culture system.

Results: Kurarinone is extensively converted to two glucuronides (M3 and M4) in HLMs. M3 formation was catalyzed by multiple UGT1As, with UGT1A3 showing the highest intrinsic clearance (120.60?mL/min/mg). M4 formation was catalyzed by UGT1A1, UGT2B4, and UGT2B7. UGT1A1 showed the highest intrinsic clearance (60.61?mL/min/mg). The kinetic profiles of the five main UGTs and HLMs fit substrate inhibition kinetics, with K_m values ranging from 5.20 to 46.52?µM, V_max values ranging from 0.20 to 3.06?µmol/min/mg, and K_si values ranging from 25.58 to 230.30?µM. The kurarinone IC₅₀ value was 93?μM in the control group, 102?μM in HLMs with NADPH, and 160?μM in HLMs with UDPGA.

Discussion and conclusion: Kurarinone glucuronidation is a detoxification pathway. This information may help to elucidate the risk factors regulating kurarinone toxicity.     

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.     

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.     

Pramipexole protects against H2O2-induced PC12 cell death

Pramipexole, a novel non-ergot dopamine (DA) agonist, has been successfully applied to the treatment of Parkinson’s disease (PD). Although the specific cause of PD remains unknown, recent studies have provided evidence that oxidative stress plays a role in the parthenogenesis of the disease. In the present study, we examined the effect of pramipexole on hydrogen peroxide (H₂O₂, 100 μM)-induced PC12 cell death, and the intracellular mechanism of this effect. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay revealed that pretreatment of PC12 cells with pramipexole (1–100 μM) resulted in significant protection against H₂O₂-induced cell death in a concentration-dependent manner. The protective effect of pramipexole was not affected by pretreatment with the DA receptor antagonists sulpiride, spiperone or domperidone, suggesting that the effect of pramipexole is not mediated by DA receptors. In PC12 cells, pramipexole inhibited H₂O₂-induced lactate dehydrogenase (LDH) leakage, as well as H₂O₂-induced cytochrome c release and caspase-3 activation with the resultant apoptosis. It was also observed in PC12 cells that H₂O₂ stimulated phosphorylation of mitogen-activated protein (MAP) kinases, i.e., extracellular signal-regulated kinase1/2 (ERK1/2), c-Jun NH₂-terminal kinase (JNK) and p38 MAP kinase. Pramipexole inhibited H₂O₂-induced JNK and p38 MAP kinase, but not ERK1/2 phosphorylation. Furthermore, in these cells experiments with a fluorescent probe, 2-[6-(4'-amino)phenoxy-3H-xanthen-3-on-9-yl]benzoic acid, revealed that pramipexole, the JNK inhibitor SP600125 and the p38 MAP kinase inhibitor SB203580 inhibited the generation of H₂O₂-induced reactive oxygen species. Caspase inhibitors Z-DEVD-FMK and Z-IETD-FMK, as well as SP600125 and SB203580, inhibited H₂O₂-induced PC12 cell death to a similar extent as pramipexole. These results suggest that pramipexole exerts a protective effect against oxidative stress-induced PC12 cell death in part through an inhibition of JNK and p38 MAP kinase.     

Functionalised collagen spheres reduce H2O2 mediated apoptosis by scavenging overexpressed ROS

Excess reactive oxygen species (ROS) has been implicated in numerous diseases including cancer, cardiovascular and neurodegenerative diseases. Overexpression of ROS can lead to oxidative stress and subsequently to H₂O₂-mediated cell apoptosis. In this study, it was demonstrated that biodegradable PLGA microspheres coated with collagen type I and decorated with MnO₂ nanoparticles acted as ROS scavengers controlling the H₂O₂-mediated apoptosis of cells undergoing oxidative stress. The results showed that the functionalized collagen spheres can protect cells even under very harsh conditions of oxidative stress.     

Salvianolic acid B protects human endothelial progenitor cells against oxidative stress-mediated dysfunction by modulating Akt/mTOR/4EBP1, p38 MAPK/ATF2, and ERK1/2 signaling pathways

The vascular endothelium is specifically sensitive to oxidative stress, and this is one of the mechanisms that causes widespread endothelial dysfunction in most cardiovascular diseases and disorders. Protection against reactive oxygen species (ROS)-mediated oxidative damage via antioxidant mechanisms is essential for tissue maintenance and shows therapeutic potential for patients suffering from cardiovascular and metabolic disorders. Salvianolic acid B (SalB), a natural bioactive component known from Traditional Chinese Medicine, has been reported to exert cellular protection in various types of cells. However, the underlying mechanisms involved are not fully understood. Here, we showed that SalB significantly promoted the migratory and tube formation abilities of human bone marrow derived-endothelial progenitor cells (BM-EPCs) in vitro, and substantially abrogated hydrogen peroxide (H₂O₂)-induced cell damage. SalB down-regulated Nox4 and eNOS, as well as nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase expression upon H₂O₂ induction that in turn prevents oxidative-induced endothelial dysfunction. Moreover, SalB suppressed the Bax/Bcl-xL ratio and caspase-3 activation after H₂O₂ induction. Furthermore, our results provide mechanistic evidence that activation of the mTOR/p70S6K/4EBP1 pathways is required for both SalB-mediated angiogenic and protective effects against oxidative stress-induced cell injury in BM-EPCs. Suppression of MKK3/6-p38 MAPK-ATF2 and ERK1/2 signaling pathways by SalB significantly protected BM-EPCs against cell injury caused by oxidative stress via reduction of intracellular ROS levels and apoptosis. Taken together, by providing a mechanistic insight into the modulation of redox states in BM-EPCs by SalB, we suggest that SalB has a strong potential of being a new proangiogenic and cytoprotective therapeutic agent with applications in the field of endothelial injury-mediated vascular diseases.     

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.