The antioxidant and antigenotoxic properties of citrus phenolics limonene and naringin

Phenolic compounds not only contribute to the sensory qualities of fruits and vegetables but also exhibit several health protective properties. Limonene and naringin are the most popular phenolics found in Citrus plants. In this study, we investigated the antioxidant capacities of limonene and naringin by the trolox equivalent antioxidant capacity (TEAC) assay and the cytotoxic effects by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in Chinese hamster fibroblast (V79) cells. The genotoxic potentials of limonene and naringin were evaluated by micronucleus (MN) and alkaline COMET assays in human lymphocytes and V79 cells. Limonene and naringin, were found to have antioxidant activities at concentrations of 2–2000 µM and 5–2000 µM respectively. IC₅₀ values of limonene and naringin were found to be 1265 µM and 9026 µM, respectively. Limonene at the concentrations below 10,000 µM and naringin at the all concentrations studied, have not exerted genotoxic effects in lymphocytes and in V79 cells. Limonene and naringin at all concentrations revealed a reduction in the frequency of MN and DNA damage induced by H₂O₂.     

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.     

Protective role of selenium in the activities of antioxidant enzymes in piglet splenic lymphocytes exposed to deoxynivalenol

We evaluated the effects of selenium (Se) on antioxidant enzymes of piglet splenic lymphocytes exposed to deoxynivalenol (DON). We measured cell viability, the activities of several antioxidant enzymes, and lactate dehydrogenase (LDH), as well as total antioxidant capacity (T-AOC) and the levels of malonaldehyde (MDA) and hydrogen peroxide (H₂O₂). We found that DON exposure increased the concentrations of LDH, MDA, and H₂O₂ in all experimental groups in a dose-dependent manner, while the concentrations of other antioxidant enzymes were decreased. In Se-pretreated DON-exposed cells, damage to antioxidant enzymes was reduced, especially in the lower-dose DON groups over longer exposure times. These results may indicate that in piglet splenic lymphocytes, Se can alleviate DON-induced damage to antioxidant enzymes by improving glutathione peroxidase activity. Se may function as a potential antioxidative agent to alleviate DON-induced oxidative stress.     

In Vitro Studies on the Antioxidant and Protective Effect of 2-Substituted -8-Hydroxyquinoline Derivatives Against H2O2-Induced Oxidative Stress in BMSCs

Novel 2-vinyl-8-hydroxyquinoline derivatives as potential antioxidants and regulators of H₂O₂-induced oxidative stress in rat bone marrow mesenchymal stem cells (MSCs) are first reported. The antiradical properties and the reducing power of these compounds were assessed using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and auto-oxidation of pyrogallol method, respectively. The activity against lipid peroxidation was determined using ammonium thiocyanate method. The results revealed that introduction of electron-donating groups at 2nd position decreased the antioxidant activities of 8-hydroxyquinoline derivatives. In addition, compound 4 , the structure of which is similar to melatonin, exhibited superior antioxidant activities in scavenging DPPH free radical, ˙O₂ free radical, and anti-LPO activities. Except for compounds 7 , 12 , and 15 , the other compounds exhibited a stimulatory effect on MSCs growth. Using hydrogen peroxide (H₂O₂), we also investigated the protective efficacy of 2-vinyl-8-hydroxyquinoline derivatives against oxidative stress-induced cell death of MSCs. Cell viability assayed by MTT method indicated that exposure of MSCs cultures to hydrogen peroxide resulted in a concentration-dependent decrease in cell viability, and compounds 4 and 5 at given concentration (2.62 × 10⁻³ m ) could protect MSCs against H₂O₂-induced oxidative stress in bone mesenchymal stem cell (BMSCs).     

洋参抗衰合剂对H2O2诱导HepG2细胞氧化损伤的保护作用

目的 考察洋参抗衰合剂对H₂O₂致HepG2细胞氧化应激损伤的保护作用,并初步分析洋参抗衰合剂对H₂O₂诱导HepG2细胞氧化损伤的保护机制。方法 以H₂O₂诱导培养的HepG2细胞为模型,检测洋参抗衰合剂对HepG2细胞中谷胱甘肽(glutathione,GSH)含量、过氧化氢酶(catalase, CAT)活力和丙二醛(malondialdehyde, MDA)含量的变化,分析洋参抗衰合剂的抗氧化作用。结果 随着洋参抗衰合剂质量浓度的增加,H₂O₂诱导HepG2细胞的谷胱甘肽(GSH) 和过氧化氢酶(CAT)含量上升,丙二醛(MDA)的含量有所下降。结论 洋参抗衰合剂对H₂O₂诱导HepG2细胞损伤有抗氧化作用,其机理可能是通过促进还原物质的合成,增加抗氧化酶的活性进而减少脂质过氧化物。     

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.     

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。     

The effect of lovastatin on oxidative stress and antioxidant enzymes in hydrogen peroxide intoxicated rat

Oxidative stress has been linked to the development of many diseases and hastens the progression of cardiovascular diseases. Since lovastatin is used worldwide as a cholesterol lowering drug, the present study was undertaken to evaluate the antioxidant property of lovastatin against H₂O₂ induced oxidative stress in rats. Four study groups of rats of four animals each were treated with DMSO (control), H₂O₂ (OS), lovastatin (L) and H₂O₂ + lovastatin (OSL). On the 15th day the animals were sacrificed, and the liver and heart tissues were analyzed for oxidative stress biomarkers and anti-oxidant enzymes. Results of the OSL-group showed a reduction in thiobarbituric acid reactive substances in liver (42.7%) and heart tissue (8%) compared with the control group. An increase was observed in the activity of the antioxidant enzymes, catalase (34.6% in liver and 33.3% in heart) and glutathione peroxidase (50.5% in liver and 34.7% in heart). A commensurate increase in the activity of G6PDH was observed indicating an enhanced requirement of NADPH. The ratio GSH:GSSG in liver (1.05) and heart (0.84) was satisfactorily regulated compared to the control group (1.01 in liver and 0.93 in heart). These results suggest that lovastatin possesses antioxidant activity and reduces oxidative stress.     

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.     

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.     

Effects on Lipid Peroxidation and Antioxidative Enzymes of Euonymus alatus in Cultured Rat Hepatocytes

Abstract: The Euonymus alatus (Thunb.) Sieb. has long been used as a crude drug. In this paper, we investigate the effects of E. alatus on cultured hepatocyte cell system and lipid peroxidation in hydrogen peroxide (H₂O₂) treatment conditions. The study covers the physiological activity (the antioxidative activity and the nitrite‐scavenging effect) of E. alatus. H₂O₂ that can produce intracellular free radical was used for inducer of the peroxidation of cellular lipids. Treatment of E. alatus attenuated in cell killing enhanced by increasing concentrations of H₂O₂. The increased malondialdehyde level induced by H₂O₂ treatment was reduced by pre‐treatment of E. alatus. Furthermore, addition of E. alatus in cell culture medium significantly reduced cell killing and content of intracellular antioxidants. Changes in nitrite‐scavenging effect of E. alatus at various concentrations (5–25 mg/ml) and various pH levels (pH 1.2, 4.2 and 6.0) were also observed. The present study was also done to investigate the effects of E. alatus on cultured hepatocyte cell system, H₂O₂‐induced cytotoxicity and antioxidative enzyme activities, including catalase, superoxide dismutase, glutathione peroxidase and glutathione S‐transferase in H₂O₂ treatment conditions. E. alatus treatment had significant protective or elevating activities on these antioxidative enzyme activities compared to a normal group. The results indicate that E. alatus provides a strong antioxidant protection of cells against H₂O₂‐induced oxidative stress.     

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.     

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.     

Effect of Hedyotis diffusa water extract on protecting human hepatocyte cells (LO2) from H2O2-induced cytotoxicity

Context: Natural products are good sources of natural dietary antioxidants that are believed to protect the body against hepatotoxic effect induced by oxidative stress. Hedyotis diffusa Willd (Rubiaceae) (HDW) is a traditional Chinese medicinal herb that has been shown to possess a variety of antioxidant properties.

Objective: The present study examines and explains the cell protective property of HDW water extract (WEHDW).

Materials and methods: 2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH) assay was used to measure the free radical scavenging property of WEHDW (0.001–10?mg/mL). The protective effect of WEHDW (0.3–10?mg/mL 2?h pretreatment) against hydrogen peroxide (H₂O_2, 200?μM for 6?h) induced cytotoxicity in human hepatic cells, LO₂, was evaluated using cell viability assay and nuclear staining. The molecular pathway of WEHDW's effect was investigated by using Western blot assay.

Results: WEHDW had a 50% scavenging concentration (SC₅₀) at 0.153?mg/mL in the DPPH assay. Exposure of LO₂ cells to H₂O₂ resulted in apoptosis which could be markedly attenuated by pre-treating WEHDW in a concentration-dependent manner (0.5, 1, 3, 5, or 10?mg/mL) (all with p?<?0.001, versus control). Moreover, Hoechst (nuclear) staining showed that 1?mg/mL WEHDW could protect LO₂ cells by attenuating apoptotic cell death mediated by H₂O₂. It was found that WEHDW reversed H₂O₂-induced activation of MEK/ERK pathway and H₂O₂-induced inhibition of P13-K/AKT/GSK3β pathway in LO₂ cells.

Discussion and conclusion: WEHDW may help to improve the antioxidant defense system, resulting in prevention of oxidative stress-related fatty liver diseases.     

Antioxidant ameliorating effects against H2O2-induced cytotoxicity in primary endometrial cells

Oxidative stress and a disrupted antioxidant system are involved in a variety of pregnancy complications. In the present study, the role of vitamin E (Vit E) and folate as radical scavengers on the GSH homeostasis in stress oxidative induced in rat endometrial cells was investigated. Primary endometrial stromal cell cultures treated with 50 and 200?µM of H₂O₂ and evaluated the cytoprotective effects of Vit E (5?µM) and folate (0.01?µM) in H₂O₂-treated cells for 24?h. Following the exposure of endometrial cells to H₂O₂ alone and in the presence of Vit E and/or folate, cell survival, glutathione peroxidase (GPx) and glutathione reductase activities and the level of reduced glutathione (GSH) were measured. Cell adhesions comprise of cell attachment and spreading on collagen were determined. Flow cytometric analysis using annexin V was used to measure apoptosis. H₂O₂ treatment showed a marked decrease in cell viability, GPx and GR activities and the level of GSH. Although Vit E or folate had some protective effect, combination therapy with Vit E and folate attenuated all the changes due to H₂O₂ toxicity. An increasing number of alive cells was showed in the cells exposed to H₂O₂ (50?µM) accompanied by co-treatment with Vit E and folic acid. The present findings indicate that co-administration of Vit E and folate before and during pregnancy may maintain a viable pregnancy and contribute to its clinical efficacy for the treatment of some idiopathic infertility.     

Nicotine induced pro-oxidant and antioxidant imbalance in rat lymphocytes: in vivo dose and time dependent approaches

The immune cells use reactive oxygen species (ROS) for carrying out their normal functions while an excess amount of ROS can attack cellular components that lead to cell damage. The present study was undertaken to determine the dose as well as time dependent effects of nicotine administration on the superoxide anion generation, lipid peroxidation and antioxidant defense systems in lymphocytes. Male Wistar rats were treated with vehicle (normal saline) and nicotine [3-(1-methyl-2-pyrrolidinyl) pyridine, C₁₀H₁₄N₂] (in physiological saline, pH was adjusted at 7.4 prior to injection) as indicated in a dose and duration fashion and the superoxide anion generation, lipid peroxidation, and antioxidant enzymes status were monitored. Superoxide anion generation, lipid peroxidation and oxidized glutathione levels were increased significantly (P < 0.05), and reduced glutathione level, activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-s-transferase were decreased significantly (P < 0.05) with the increasing dose and duration of nicotine treatment. The highest changes in lymphocytes were observed at the dose of 1.0?mg/kg/day for 7 days. It may be concluded that nicotine is able to enhance the production of ROS that produced oxidative stress in lymphocytes in a dose and time dependent manner.     

Continuous presence of H2O2 induces mitochondrial-mediated,MAPK- and caspase-independent growth inhibition and cytotoxicity in human gingival fibroblasts

The continuous generation of reactive oxygen species (ROS) is one of the most important events that occur during periodontal inflammation. Hydrogen peroxide (H₂O₂) is widely used in dental clinics. Many investigators have tried to elucidate the exact effect of H₂O₂ on human gingival fibroblasts (HGFs). These studies have shown that H₂O₂ induces growth inhibition and apoptosis in cells. However, the mechanisms involved in H₂O₂-induced cell death in HGFs are not completely understood. In this study, we examine how continuously generated H₂O₂ affects the viability and proliferation of HGFs using glucose oxidase (GO). We also explored the mechanisms by which the continuous presence of H₂O₂ induces cell death. GO treatment not only inhibited HGF growth and proliferation, but it also induced cell death in HGFs without typical apoptotic features such as nuclear DNA laddering. This GO-mediated cytotoxicity was proportional to the levels of intracellular ROS that were generated, rather than proportional to changes of cellular antioxidant activities. GO treatment also resulted in the loss of mitochondrial membrane potential and the relocation of mitochondrial apoptogenic factors. There was also an acute and severe depletion of cellular ATP levels. However, none of the pharmacological inhibitors specific for mitogen-activated protein kinases (MAPKs) or pancaspase prevented GO-induced cell death. Treatment with either catalase or acteoside significantly attenuated the GO-mediated cytotoxicity in the HGFs, thereby suggesting a protective effect of antioxidants against ROS-mediated gingival damage. Here we demonstrate that continuously generated H₂O₂ not only inhibits the viability and proliferation of HGFs, but also causes pyknotic/necrotic cell death through mitochondrial stress-mediated, MAPK- and caspase-independent pathways.     

Antioxidant potential of aqueous extract of Phyllanthus amarus in rats

Objective:

Increased levels of oxidative stress may be implicated in the etiology of many pathological conditions. Protective antioxidant action imparted by many plant extracts and plant products make them promising therapeutic drugs for free radical induced pathologies. In this study we assessed the antioxidant potential of Phyllanthus amarus (Euphorbiaceae).

Materials and Methods:

Experimental rats were divided into two groups: Control and Phyllanthus amarus (P. amarus) treated. Treated rats received P. amarus aqueous extract (PAAEt) at a dose of 200 mg/kg body wt/day for 8 weeks. After the treatment period of 8 weeks lipid peroxidation (LPO), vitamin C, uric acid and reduced glutathione (GSH) were estimated in plasma and antioxidant enzymes: Glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) were also assayed. Genotoxicity of PAAEt was assessed by single cell gel electrophoresis (SCGE) of lymphocytes under both in vitro and in vivo conditions. The protective role of PAAEt against hydrogen peroxide (H₂O₂), streptozotocin (STZ) and nitric oxide generating system induced lymphocyte DNA damage was also assessed by SCGE.

Results:

PAAEt treated rats showed a significant decrease in plasma LPO and a significant increase in plasma vitamin C, uric acid, GSH levels and GPx, CAT and SOD activities. SCGE experiment reveals that PAAEt was devoid of genotoxicity and had a significant protective effect against H₂O₂, STZ and nitric oxide (NO) induced lymphocyte DNA damage.

Conclusion:

The results suggest the non-toxic nature of PAAEt and consumption of PAAEt can be linked to improved antioxidant status and reduction in the risk of oxidative stress.     

Fluroxypyr triggers oxidative damage by producing superoxide and hydrogen peroxide in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis>)

The present study has evaluated effect of fluroxypyr concentrations 0–0.8 mg l⁻¹ (a widely-used herbicide for controlling annual or perennial weeds growth) on selected metabolic and stress-related parameters in Oryza sativa plants after 6 days of exposure. Increasing concentrations decreased shoot growth and accumulation of chlorophylls but had no effect on root biomass. Increasing doses led also to increase in superoxide radical, hydrogen peroxide and proline accumulation, while malondialdehyde, an indicator of lipid peroxidation, was constitutively elevated. Histochemical staining with nitroblue tetrazolium and 3, 3-diaminobenzidine were positively correlated with the generation of superoxide radical and H₂O₂. The fluroxypyr-induced oxidative stress triggered significant changes in activities of superoxide dismutase, catalase, ascorbate peroxidase and peroxidase (POD). Activities of the antioxidant enzymes show a general increase at low fluroxypyr concentrations and a decrease at high fluroxypyr levels (except for POD). Analysis of naturing polyacrylamide gel electrophoresis confirmed these results. These data support the observation that fluroxypyr-triggered oxidative stress was responsible for the disturbance of the growth in the rice plants.     

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.