Reactive Oxygen Species Scavenging Effects Research Articles

Ascorbic acid addition during dehydration improves garlic shoot tip cryopreservation but does not affect viral load

Cryopreservation is known be an effective method for virus elimination in garlic. However, oxidative damage during the cryopreservation seriously affects the survival of garlic after cryopreservation. Ascorbic acid (AsA) can reduce oxidative damage and improve regrowth following cryopreservation, and its effect may be influenced by the step during which it is added. In this study, AsA was added at the osmoprotection (O) and dehydration (DE) steps of cryopreservation. By observing the dynamic changes in cell viability and reactive oxygen species (ROS) components with different AsA treatments, AsA has been linked to the reduced accumulation of ROS in the shoot tips. Increased gene expression levels of antioxidant enzymes also explained the ROS scavenging effect of AsA. The correlation analysis between cell viability, ROS, membrane lipid peroxidation-related indicators and antioxidant-related indicators showed that membrane lipid peroxidation caused by excess ROS was the main factor affecting cell viability. Ascorbic acid added during dehydration minimized the accumulation of ROS from dehydration to dilution and alleviated the oxidative damage during cryopreservation. Thus, the survival and regrowth of the garlic was significantly improved after cryopreservation. Dehydration was found to be the suitable step for the addition of AsA during garlic cryopreservation. We further evaluated the virus elimination effect under optimal AsA treatment. However, there was no significant difference in virus content in regenerated plants when compared with the control.

Oxidative stress‐mediated up‐regulation of ABC transporters in lung cancer cells

This paper aimed to evaluate the role of oxidative stress in the regulation of ABC transporters in human lung cancer (A549) cells facing substrate (doxorubicin, DOX) and nonsubstrate (ethanol, ETH and hydrogen peroxide, HP) chemicals. After 24-h treatment, all the chemicals caused significant cytotoxicity as reflected by the reduction in cell viability and the increase in reactive oxygen species (ROS) levels. Depending on the rescuing effects of ROS scavenger including glutathione (GSH) and Vitamin C, the toxicity dependence on oxidative stress were found to be HP > ETH > DOX. The addition of transporter inhibitors significantly enhanced the ROS levels and death-inducing effects of chemicals, indicating the universal detoxification function of ABC transporters. At moderate ROS levels (about 3-4-folds of control levels, caused by 10 μM DOX, 400 mM ETH, and 400 μM HP), all the three chemicals induced the gene expressions and activities of ABC transporters, but these values decreased at too high ROS levels (8.36-folds of control levels) caused by HP at LC50 (800 μM). Such induction could be attenuated by GSH and KCZ, and was completely abolished by 50 μM KCZ, indicating an important role of oxidative stress and pregnane X receptor (PXR) in the induction of ABC transporters. Finally, this paper revealed the critical role of oxidative stress in the modulation of ABC transporters by either substrate or nonsubstrate chemicals during 24-h treatment. Such information should be beneficial for overcoming ABC transporter-mediated multidrug resistance.

Polycatechol-Derived Mesoporous Polydopamine Nanoparticles for Combined ROS Scavenging and Gene Interference Therapy in Inflammatory Bowel Disease.

Benefiting from the evolution of nanotechnology, the combination therapy by gene interference and reactive oxygen species (ROS) scavenging are expected, which holds great potential in inflammatory bowel disease (IBD) therapy. However, the functional integration of different therapeutic modules through interface modification of gene vectors for safe and efficient treatment is urgently needed. Herein, we present a catechol chemistry-mediated core-shell nanoplatform for ROS scavenging-mediated oxidative stress alleviation and siRNA-mediated gene interference in a dextran sulfate sodium (DSS)-induced colitis model. The nanoplatform is constructed by employing mesoporous polydopamine nanoparticles (MPDA NPs) with surface modification of amines as the porous core for TNF-α-siRNA loading (31 wt %) and exerts an antioxidant function, while PDA-induced biomineralization of the calcium phosphate (CaP) coating is used as the pH-sensitive protective shell to prevent siRNA from premature release. The CaP layer degraded under weakly acidic subcellular conditions (lysosomes); thus, the synergistic integration of catechol and cation moieties on the exposed surface of MPDA resulted in an efficient lysosomal escape. Subsequently, effective ROS scavenging caused by the electron-donating ability of MPDA and efficient knocking down (40.5%) of tumor necrosis factor-α (TNF-α) via sufficient cytosolic gene delivery resulted in a synergistic anti-inflammation therapeutic effect both in vitro and in vivo. This work establishes the first paradigm of synergistic therapy in IBD by ROS scavenging and gene interference.

Anti-oxidative and mucin-compensating dual-functional nano eye drops for synergistic treatment of dry eye disease

Oxidative stress plays a central role in dry eye disease (DED), which can destroy the mucin layer on the ocular surface. The currently available eye drops are palliative and short-lived. Thus, a therapy that can continuously scavenge the overexpressed reactive oxygen species (ROS) and promote mucin production in DED is quite necessary. Thus, we have developed a synergistic nanoparticle (NP) that can treat DED by scavenging ROS and promoting mucin production. Mesoporous polydopamine (mPDA) NPs were prepared by one-pot synthesis and loaded with melatonin (Mel) and tavilermide (Tav) (mPDA@Mel-Tav). The mPDA NPs loaded with 20% Mel and 2% Tav showed good cytocompatibility. Mel and Tav were continuously released from mPDA@Mel-Tav NPs, and the release of Mel was slower than that of Tav. The ROS level and apoptosis ratio were decreased in the presence of mPDA@Mel-Tav, indicating the central role of Mel in ROS scavenging and antioxidant effect. Meanwhile, Tav promoted the production of mucins on the ocular surface. The retention time of mPDA was longer than that of normal eye drops. The corneal fluorescence staining score of mice with DED in mPDA@Mel-Tav treatment group was lower than in other treated groups, indicating the good therapeutic effect of mPDA@Mel-Tav in DED. In summary, we synthesized the mPDA@Mel-Tav NP eye drop to achieve a sustained release of Mel and Tav, which could effectively treat DED by scavenging ROS and promoting mucin production. This dual-functional NP represents a promising treatment strategy for DED and other multi-cause diseases.

H2O2-Elicitation of Black Carrot Hairy Roots Induces a Controlled Oxidative Burst Leading to Increased Anthocyanin Production.

Hairy roots (HRs) grown in vitro are a powerful platform for plant biotechnological advances and for the bio-based production of metabolites of interest. In this work, black carrot HRs able to accumulate anthocyanin as major secondary metabolite were used. Biomass and anthocyanin accumulation were improved by modulating growth medium composition—different Murashige & Skoog (MS)-based media—and H2O2-elicitation, and the level of the main antioxidant enzymes on elicited HRs was measured. Higher growth was obtained on liquid 1/2 MS medium supplemented with 60 g/L sucrose for HRs grown over 20 days. In this medium, 200 µM H2O2 applied on day 12 induced anthocyanin accumulation by 20%. The activity of superoxide dismutase (SOD)—which generates H2O2 from O2•−—increased by over 50%, whereas the activity of H2O2-scavenging enzymes was not enhanced. Elicitation in the HRs can result in a controlled oxidative burst, in which SOD activity increased H2O2 levels, whereas anthocyanins, as effective reactive oxygen species scavengers, could be induced to modulate the oxidative burst generated. Moreover, given the proven stability of the HR lines used and their remarkable productivity, this system appears as suitable for elucidating the interplay between antioxidant and secondary metabolism.

The halophyte gene ScVTC2 confers resistance to oxidative stress via AsA-mediated photosynthetic enhancement

Various abiotic stresses commonly cause excessive production of reactive oxygen species (ROS) and result in oxidative stress, which challenges the physiological homeostasis of plants. Maintaining a delicate balance between ROS generation and removal is critical for plants to cope with stressful environments. Suaeda corniculata is a typical euhalophyte with strong tolerance to salt stress, but its mechanism of ROS detoxification to prevent oxidative stress is unknown. Here, a combined analysis of RNA-Seq and photosynthetic assays was performed on S. corniculata under oxidative stress to uncover the underlying mechanism that modulates oxidative tolerance. Our results showed that all genes involved in the pathway of ROS scavenging, especially the AsA-GSH pathway, were highly enriched under oxidative stress. Notably, VTC2 (GGPase), which functions in the L-galactose pathway of AsA synthesis, was significantly upregulated. Arabidopsis transgenic plants with heterologous expression of ScVTC2 showed elevated AsA and increased tolerance to oxidative stress. Furthermore, ScVTC2 also established better photosynthetic capacity in these plants upon oxidative treatment. Thus, ScVTC2 not only functioned as an effective ROS scavenger but also as a protector of the photosynthetic apparatus in S. corniculata and allowed plants to respond to and tolerate oxidative stress.

Mechanism of Nitrogen-Doped Ti3C2 Quantum Dots for Free-Radical Scavenging and the Ultrasensitive H2O2 Detection Performance.

MXene quantum dots feature favorable biological compatibility and superior optical properties, offering great potential for biomedical applications such as reactive oxygen species (ROS) scavenging and fluorescence sensing. However, the ROS scavenging mechanism is still unclear and the MXene-based materials for ROS sensing are still scarce. Here, we report a nitrogen-doped titanium carbide quantum dot (N-Ti3C2 QD) antioxidant with effective ROS scavenging ability. The doped nitrogen atoms promote the electrochemical interaction between N-Ti3C2 QDs and free radicals and thus enhance their antioxidant performance. Density functional theory (DFT) simulations reveal the hydroxyl radical quenching process and confirm that the doped N element promotes the free-radical absorption ability, especially for -F and -O functional groups in N-Ti3C2 QDs. Furthermore, N-Ti3C2 QDs show rapid, accurate, and remarkable sensitivity to hydrogen peroxide in the range of 5 nM-5.5 μM with a limit of detection of 1.2 nM within 15 s, which is the lowest detection limit of the existing fluorescent probes up to now. Our results provide a new category of antioxidant materials, a real-time hydrogen peroxide sensing probe, promoting the research and development of MXene in bioscience and biotechnology.

Do Autophagy Enhancers/ROS Scavengers Alleviate Consequences of Mild Mitochondrial Dysfunction Induced in Neuronal-Derived Cells?

Mitochondrial function is at the nexus of pathways regulating synaptic-plasticity and cellular resilience. The involvement of brain mitochondrial dysfunction along with increased reactive oxygen species (ROS) levels, accumulating mtDNA mutations, and attenuated autophagy is implicated in psychiatric and neurodegenerative diseases. We have previously modeled mild mitochondrial dysfunction assumed to occur in bipolar disorder (BPD) using exposure of human neuronal cells (SH-SY5Y) to rotenone (an inhibitor of mitochondrial-respiration complex-I) for 72 and 96 h, which exhibited up- and down-regulation of mitochondrial respiration, respectively. In this study, we aimed to find out whether autophagy enhancers (lithium, trehalose, rapamycin, and resveratrol) and/or ROS scavengers [resveratrol, N-acetylcysteine (NAC), and Mn-Tbap) can ameliorate neuronal mild mitochondrial dysfunction. Only lithium (added for the last 24/48 h of the exposure to rotenone for 72/96 h, respectively) counteracted the effect of rotenone on most of the mitochondrial respiration parameters (measured as oxygen consumption rate (OCR)). Rapamycin, resveratrol, NAC, and Mn-Tbap counteracted most of rotenone’s effects on OCR parameters after 72 h, possibly via different mechanisms, which are not necessarily related to their ROS scavenging and/or autophagy enhancement effects. The effect of lithium reversing rotenone’s effect on OCR parameters is compatible with lithium’s known positive effects on mitochondrial function and is possibly mediated via its effect on autophagy. By-and-large it may be summarized that some autophagy enhancers/ROS scavengers alleviate some rotenone-induced mild mitochondrial changes in SH-SY5Y cells.

Chitosan Nanococktails Containing Both Ceria and Superparamagnetic Iron Oxide Nanoparticles for Reactive Oxygen Species-Related Theranostics

Reactive oxygen species (ROS) play an essential role in the progression of many chronic diseases like atherosclerosis and rheumatoid arthritis. For decades, antioxidant compounds have always been considered as potential treatments for these ROS-related diseases. Concomitantly, noninvasive imaging systems such as magnetic resonance imaging (MRI) have also been widely used in the diagnosis of diseases, especially atherosclerosis. In this study, we investigated the feasibility to develop chitosan nanococktails containing both nanoceria and superparamagnetic iron oxide nanoparticles for ROS-related theranostics. Nanoceria utilized as therapeutic modules capable of ROS scavenging and iron-oxide nanoparticles utilized as imaging agents for MRI have been synthesized separately. Subsequently, two versions of theranostic chitosan nanococktails containing both nanoceria and iron oxide nanoparticles (Chit-IOCO and Chit-TPP-IOCO) were successfully synthesized via two different mechanisms, electrostatic self-assembly, and ionic gelation. In vitro studies such as cytotoxicity, MRI, and ROS scavenging were performed. These theranostic nanococktails demonstrated effective ROS scavenging and MRI contrast as a potential platform for treatment and diagnosis of ROS-related diseases. Results indicated that both Chit-IOCO and Chit-TPP-IOCO can reduce the ROS level of the lipopolysaccharide-stimulated macrophage J774A.1 to the baseline level. Chit-IOCO was less toxic to the cells than Chit-TPP-IOCO. In addition, Chit-IOCO exhibited higher MRI relaxivity than Chi-TPP-IOCO (308 and 150 mM-1 s-1, respectively), indicating that Chi-IOCO was more effective than Chit-TPP-IOCO as an MRI contrast agent in macrophages. Taken together, Chit-IOCO nanococktail demonstrates outstanding potential for treatment and diagnosis of ROS-related diseases. Potentially, this nanococktail can be easily modified to include new modules, allowing future application of personalized medicine.

Protective effect of ethyl pyruvate on gut barrier function through regulations of ROS-related NETs formation during sepsis

BackgroundSepsis impairs the function of the intestinal barrier through neutrophil extracellular traps (NETs). Reactive oxygen species (ROS)-induced activation of mitogen-activated protein kinase (MAPK) is involved in NET formation. Ethyl pyruvate (EP), a potent and effective ROS scavenger, ameliorates sepsis-associated intestinal barrier dysfunction, but the detailed mechanism is unknown. The current study aimed to explore the eff ;ects of EP on sepsis-induced intestinal barrier dysfunction and whether ROS and NETs were involved. MethodsA sepsis model was induced in mice by intraperitoneal injection of LPS (10 mg/kg). The mice were divided into 4 groups: (1) sham group; (2) LPS group; (3) DNase-1 + LPS group; and (4) EP + LPS group. EP or DNase-1 was intraperitoneally injected after the LPS model was established. After 24 h, the small intestine and blood were collected for analysis. Human neutrophils were harvested and incubated with phorbol-12-myristate-13-acetate (PMA) or PMA + EP, and ROS and NET generation was measured. ResultsEP significantly decreased proinflammatory cytokines and MPO-DNA in the LPS model. In addition, EP suppressed NET formation in the intestines of endotoxemic mice. The decrease in NETs induced by EP or DNase-1 alleviated histopathological damage, intestinal cell apoptosis and increased tight junction expression. In vitro, the treatment of EP abolished PMA-induced ROS production and NET formation which could be reversed by H2O2 treatment. Meanwhile, EP also abolished MAPK ERK1/2 and p38 activation during PMA-induced NET formation. ConclusionThis study was the first to demonstrate that EP alleviated NET formation and sepsis-induced intestinal damage through blockage of ROS mediated MAPK ERK1/2 and p38 activation.

Poly(acrylic acid)-mediated synthesis of cerium oxide nanoparticles with variable oxidation states and their effect on regulating the intracellular ROS level.

Cerium oxide nanoparticles (CeNPs) possess multiple redox enzyme mimetic activities in scavenging reactive oxygen species (ROS) as a potential biomedicine. These enzymatic activities of CeNPs are closely related to their surface oxidation state. Here we have reported a synthetic method to modify CeNPs' surface oxidation state by changing the conformation of the poly(acrylic acid) (PAA) polymers adsorbed onto the CeNP surface. The synthesized PAA-CeNPs exhibited the same core size, morphology, crystal structure, and colloidal stability, with the only variation being their surface oxidation state (Ce3+ percentage). The modification mechanism can be attributed to the polymers chemisorbed onto the metal oxide surface forming a metal complexation structure. Such adsorption further modified CeNPs' surface oxidation state in a temperature-dependent manner. The series of PAA-CeNPs exhibited multiple redox enzyme mimetic activities (superoxide dismutase, catalase, peroxidase, and oxidase) directly related to their surface oxidation state. In vitro experiments showed no cytotoxic effect of these PAA-CeNPs on the osteoblastic cell line SAOS-2 at high loadings. Microscopic images confirmed the internalization of PAA-CeNPs in the cells. All tested PAA-CeNPs can reduce the basal and hydrogen peroxide-induced intracellular ROS level in the cells, indicating their effective intracellular ROS scavenging effect. However, we did not observe a positive correlation between the CeNP surface oxidation state and their capacities to reduce the intracellular ROS levels. We propose that CeNPs can maintain a dynamic state of Ce3+/Ce4+ during their catalytic activities, exhibiting a non-linear correlation between the CeNP surface oxidation state and their effect on regulating the intracellular ROS level.

Inhibition of oxidative stress induced-cytotoxicity by coptisine in V79-4 Chinese hamster lung fibroblasts through the induction of Nrf-2 mediated HO-1 expression.

Coptisine is a natural alkaloid compound and is known to have multiple beneficial effects including antioxidant activity. However, whether it can protect lung fibroblasts from oxidative damage has not been studied yet. To investigate the potential inhibitory effect of coptisine against oxidative stress in V79-4 lung fibroblast cells. V79-4 cells were treated with H2O2 (1mM) in the presence or absence of coptisine (50 µg/ml), N-acetyl cysteine (NAC, 10mM) or zinc protoporphyrin IX (ZnPP, 10 µM) for the indicated times. The alleviating effects of coptisine on cytotoxicity, cell cycle arrest, apoptosis, reactive oxygen species (ROS) production, DNA damage, mitochondrial dynamics, and inhibition of ATP production against H2O2 were investigated. Western blot analysis was used to analyze the expression levels of specific proteins. Coptisine inhibited H2O2-induced cytotoxicity and DNA damage by blocking abnormal ROS generation. H2O2 treatment caused cell cycle arrest at the G2/M phase accompanied by increased expression of cyclin-dependent kinase (Cdk) inhibitor p21WAF1/CIP1 and decreased expression of cyclin B1 and cyclin A. However, these effects were attenuated in the presence of coptisine or NAC. Coptisine also prevented apoptosis by decreasing the rate of Bax/Bcl-2 expression in H2O2-stimulated cells and suppressing the loss of mitochondrial membrane potential and the cytosolic release of cytochrome c. In addition, the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was markedly promoted by coptisine in the presence of H2O2. However, zinc protoporphyrin IX, a potent inhibitor of HO-1, attenuated the ROS scavenging and anti-apoptotic effects of coptisine. Based on current data, we suggest that coptisine can be used as a potential treatment for oxidative stress-related lung disease.

ROS-Scavenging Nanomaterials to Treat Periodontitis.

The incidence of periodontitis is very high, and up to 45–50% of people are suffering from periodontitis. Periodontitis is caused by pathogens that invade teeth-supporting tissues such as gingiva, periodontal ligament, and alveolar bone. Pathogens trigger host immune responses characterized by the overproduction of reactive oxygen species (ROS). The development of effective ROS scavengers through nanotechnology has been emerging as a promising strategy for the treatment of periodontitis. Nanomaterial-based antioxidants can effectively scavenge ROS, prevent ROS-mediated tissue damage, and relieve inflammation in periodontitis. This mini-review focuses on the generation of ROS in periodontitis and its molecular mechanism of destroying periodontal tissue. Meanwhile, we summarize the research progress of ROS-scavenging nanomaterials in the treatment of periodontitis and discuss the challenges and prospects of its application.

Trans-Cinnamaldehyde Prevents Oxidative Stress-Induced Apoptosis in V79-4 Chinese Hamster Lung Fibroblasts through the Nrf2-Mediated HO-1 Activation.

Oxidative stress, which is characterized by overproduction of reactive oxygen species (ROS), is considered a major risk factor associated with fibroblast death in severe lung diseases such as idiopathic pulmonary fibrosis. trans-Cinnamaldehyde (tCA), the major phytochemical constituent in cinnamon, is known to possess strong anti-oxidant activity. However, whether tCA can defend lung fibroblasts against oxidative injury remains to be elucidated. Therefore, this study was conducted to investigate the protective effects of tCA on oxidative stress in V79-4 Chinese hamster lung fibroblasts. The current results showed that tCA inhibited hydrogen peroxide (H2O2)-induced cytotoxicity by blocking abnormal accumulation of ROS in V79-4 Chinese hamster lung fibroblasts. tCA attenuated apoptosis by suppressing of mitochondrial dysfunction and cytosolic release of cytochrome c, increasing the rate of Bcl-2/Bax expression and reducing the activity of caspase-9 and caspase-3 in H2O2-stimulated V79-4 cells, suggesting that tCA protected V79-4 cells from the induction of mitochondria-mediated apoptosis by H2O2. Additionally, the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2) was markedly promoted by tCA in the presence of H2O2, which was associated with the enhanced expression of heme oxygenase-1 (HO-1). However, inhibiting the activity of HO-1 by zinc protoporphyrin IX, a potent inhibitor of HO-1, eliminated the ROS scavenging and protective effects of tCA, indicating that tCA was able to protect V79-4 lung fibroblasts from H2O2-induced oxidative stress by activating the Nrf2 signaling pathway. Therefore, it is suggested that tCA may be useful as a candidate for the treatment of oxidative stress-mediated lung injuries in the future.

Indole-6-Carboxaldehyde Isolated from Sargassum thunbergii (Mertens) Kuntze Prevents Oxidative Stress-Induced Cellular Damage in V79-4 Chinese Hamster Lung Fibroblasts through the Activation of the Nrf2/HO-1 Signaling Pathway.

The disruption of redox equilibrium by oxidative stress, which is characterized by an overproduction of reactive oxygen species (ROS), is considered to be associated with fibroblast death in severe lung diseases. Indole-6-carboxaldehyde (I6CA) is a natural indole derivative isolated from Sargassum thunbergii, which a type of brown algae. However, the antioxidative effects of I6CA, and their mechanisms, have not been identified. This study was conducted to investigate the potential protective effects of I6CA against oxidative stress in V79-4 Chinese hamster lung fibroblasts. Cell viability and mechanisms related to antioxidant activity of I6CA (ROS production, cell cycle, DNA damage, mitochondrial membrane potential (MMP) and apoptosis) were studied. Western blot analysis was carried out to understand the involvement of various genes at protein level. Our results demonstrated that I6CA inhibited hydrogen peroxide (H2O2)-induced cytotoxicity by blocking abnormal ROS accumulation. H2O2 treatment of V79-4 fibroblasts caused cell cycle arrest at the G2/M phase, which was accompanied by increased expression of the cyclin-dependent kinase (Cdk) inhibitor p21WAF1/CIP1 and decreased expression of cyclin B1 and cyclin A. However, these effects were attenuated by treatment with I6CA. I6CA also effectively protected V79-4 cells against H2O2-induced apoptosis by increasing the Bcl-2/Bax ratio and suppressing the loss of MMP and the cytosolic release of cytochrome c. In addition, the activation of nuclear factor-erythroid-2-related factor 2 (Nrf2) was markedly promoted by I6CA, which was associated with enhanced expression and activity of heme oxygenase-1 (HO-1). However, inhibiting the activity of HO-1 by zinc protoporphyrin IX, a potent inhibitor of HO-1, eliminated the ROS scavenging and anti-apoptotic effects of I6CA, indicating that I6CA was able to protect V79-4 lung fibroblasts from H2O2-induced oxidative stress by activating the Nrf2 signaling pathway. We suggest that I6CA may be useful as a candidate therapeutic agent for the treatment of oxidative stress-related lung diseases.

Intracellular reactive oxygen species scavenging effect of fucosterol isolated from the brown alga <i>Sargassum crassifolium</i> in Vietnam

Sargassum is a widely distributed marine brown algal genus in Vietnam and has been considered a source of diverse bioactive metabolites. In this study, S. crassifolium collected from South Central region of Vietnam was chemically studied and bioactively evaluated. Fucosterol was isolated and identified from the methanolic extract of the alga by means of chemical fractionation and spectral analysis and showed no cytotoxic effect in Hep-G2 cells at the observed concentrations. In vitro assay for intracellular reactive oxygen species by dichlorofluorescein method revealed a potent scavenging effect of the isolated compound. Accordingly, the level of intracellular reactive oxygen species induced by hydrogen peroxide (H2O2) was reduced by 71.66% with the treatment of fucosterol at 10 µg.ml-1. The results indicated the ability of algal fucosterol in diffusing into cells and preventing the production of different ROS compounds and further suggested the therapeutic potential against diseases caused by oxidative stress of natural metabolites from S. crassifolium in Vietnam.

Trolox is more successful than allopurinol to reduce degenerative effects of testicular ischemia/reperfusion injury in rats

Reperfusion surgery following testicular ischemia is a reproductive health threatening status and may result with organ dysfunction in men. The high level of reactive oxygen species (ROS) and cease of blood flow to the testis are the most important reasons of this testicular injury. Until today, numerous experimental studies reported that antioxidants might be efficient to alleviate oxidative stress induced organ dysfunction. For this purpose, in this study, we have investigated the protective effects of xanthine oxidase (XO) inhibitor, allopurinol, and ROS scavenger, trolox, in a comparative perspective in testicular ischemia reperfusion injury subjected rats. Twenty-eight adult male Sprague Dawley rats were divided into four groups of seven animals in each; control, ischemia/reperfusion (I/R), allopurinol and trolox. The rats in control group did not receive any application. Animals in I/R, allopurinol and trolox groups were subjected to 2h testicular reperfusion injury following 5h ischemia. Intraperitoneally (i.p.) 1ml isotonic, 200mg/kg allopurinol and 50mg/kg trolox were administered to the animals in these groups 30min prior reperfusion. At the end of experiment, all animals were sacrificed and blood serum malondialdehyde (MDA) levels were measured. Histological sections were obtained from the testis and stained with hematoxylin and eosin (H&E), proliferating cell nuclear antigen (PCNA) and cleaved caspase-3. Apoptotic index was evaluated with TUNEL Assay. Severe morphological degenerations, increased serum MDA, cleaved caspase-3 and TUNEL Assay positivity rate, but reduced PCNA positivity rate was observed in ischemia and reperfusion group. Morphological degenerations, MDA level, apoptotic index and PCNA positive cell rate were slightly alleviated in allopurinol administered animals compared with ischemia and reperfusion group. Protection with trolox was more successful and the results of the analysis were similar to the control group. Ischemia that leading to testicular torsion is a reproductive health affecting problem and current surgical treatment methods might be insufficient to recover testis. Various types of ROS generating mechanisms in cell are limiting protective potency of allopurinol, and cocktail administration of different ROS inhibitors might be more effective. However, our results indicate that free radical scavenger trolox might be a candidate drug to alleviate degenerative effects of testicular ischemia reperfusion injury. This is the first study that demonstrates antioxidant trolox was more successful than XO inhibitor allopurinol to protect testis against ischemia and reperfusion injury in rats.

AOP1, a New Live Cell Assay for the Direct and Quantitative Measure of Intracellular Antioxidant Effects.

Taking advantage of Light Up Cell System (LUCS) technology, which allows for fine monitoring of reactive oxygen species (ROS) production inside live cells, a new assay called Anti Oxidant Power 1 (AOP1) was developed to specifically measure ROS and/or free-radical scavenging effects inside living cells. This method is quantitative and EC50s obtained from AOP1 dose-response experiments were determined in order to classify the intracellular antioxidant efficacy of 15 well known antioxidant compounds with different hydrophilic properties. Six of them (epigallocatechin gallate, quercetin, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), ethoxyquin, resveratrol) gave EC50s in the range of 7–64 μM, four (Trolox, catechin, epicatechin, EUK134) in the range of 0.14 to 1 mM, and 5 (sulforaphane, astaxanthin, α- and γ-tocopherols, vitamin E acetate) showed only partial or no effect. Interestingly, effects with measurable EC50s were observed for compounds with hydrophilic properties (LogP ≤ 5.3), while all antioxidants known to act at the plasma membrane level (LogP ≥ 10.3) had partial or no effect. Sulforaphane, a hydrophilic but strict Keap1/Nrf2 pathway enhancer, did not show any effect either. Importantly, AOP1 assay captures both antioxidant and prooxidant effects. Taken together, these results led us to the conclusion that AOP1 assay measures antioxidant effect of compounds that selectively enter the cell, and act as free radical scavengers in the cytosol and/or nucleus level.

Effects of reactive oxygen species scavengers on thermophilic micro-aerobic digestion for sludge stabilization

In thermophilic digestion systems, sludge stabilization may be adversely impacted by high concentrations of ammonia nitrogen or the rapid accumulation of fatty acids; however, few studies have focused on the mitigation of the inhibition of reactive oxygen species (ROS). In this study, fulvic acids or tea polyphenols were introduced to a thermophilic digestion system and the effects of ROS scavengers on sludge stabilization were investigated. As fulvic acids or tea polyphenols were added to sludge, they reacted with metal cations, such as Cu2+ and Zn2+, to form stable complexes that enabled active metal ions to be transported into cells to enhance the oxidase activities. Therefore, the digestion systems presented a lower O2•- content compared with that of a control group with no additive. Both fulvic acids and tea polyphenols mitigated the adverse effects of the ROS and enhanced the reduction of volatile solids (VS), however, fulvic acids better facilitated the sludge stabilization. The optimal dosage was 0.3% of the total solids as fulvic acids were added to the sludge every 48 h. The VS reduction in the digester reached 38.2% at 14 d, which was clearly higher than that in the control group. The pathway of ROS scavengers affecting sludge stabilization was proposed, and it may be helpful to gain deeper insight into the characteristics of thermophilic digestion processes as well as the mechanism of sludge stabilization.

Photocatalytic degradation of organic micropollutants: Inhibition mechanisms by different fractions of natural organic matter

Natural organic matter (NOM) can inhibit the photocatalytic degradation of organic micropollutants (OMPs) through inner filter effect, reactive oxygen species (ROS) scavenging, and competitive adsorption. However, previous studies have focused solely on the bulk properties of NOM and our understanding of the inhibition mechanism by NOM fractions during photocatalytic degradation of OMP is still fragmentary. In this study, five well-characterized different NOM samples (i.e., secondary treated wastewater, river water, and three standard NOM surrogates) were used to elucidate the inhibition mechanisms during photocatalytic degradation of carbamazepine (a model OMP) using TiO2 and its composites with carbon nanotubes (CNT-TiO2) under UVC and solar-light irradiation. The results indicated that terrestrially derived NOM with high aromaticity, a low oxygen/carbon atom ratio, and large molecular weight is the major fraction that participates in ROS scavenging, competitive adsorption, and inner filter effect. Furthermore, the modeling analysis suggested that inner filter effect due to NOM and ROS scavenging was the most influential inhibitory mechanism. In the case of secondary treated wastewater, the presence of high concentrations of inorganic species (e.g., PO43−, Cl−, and NO3−) together with NOM significantly reduced the photocatalytic degradation of carbamazepine. Overall, the methods and the results of this study provide a comprehensive understanding of the effects of NOM fractions on photocatalysis and highlight the need to further consider the interplay between NOM and background inorganic constituents in photocatalytic degradation of OMP.