Intracellular Catalase Activity Research Articles

Understanding the mechanisms behind the antibacterial activity of magnesium hydroxide nanoparticles against sulfate-reducing bacteria in sediments

Nanomaterials, with their small size, surface characteristics, and antibacterial properties, are extensively employed across environmental, energy, biomedical, agricultural, and other industries. This study examined the antibacterial efficacy of magnesium hydroxide (Mg(OH)2) nanoparticles (NPs) against sulfate-reducing bacteria (SRB) within sediments. The inhibitory effects of two types of Mg(OH)2 NPs with distinct particle sizes (20.3 and 29.6 nm) and concentrations (0–10.0 mg/mL) were examined under optimal treatment conditions. The antibacterial mechanisms of Mg(OH)2 NPs through direct contact and dissolution effects were determined. The results revealed a correlation between the concentration, particle size, and inhibitory activity, with the smallest NPs (20.3 nm) at the highest concentration (10.0 mg/mL) substantially reducing SRB counts from 8.77 ± 0.18 to 6.48 ± 0.13 log10 colony forming units/mL after 6 h treatment. Treatment with high concentrations of Mg(OH)2 NPs induced cellular damage, reduced intracellular lactate dehydrogenase activity, and elevated intracellular catalase activity and H2O2 content, suggesting that the contact effect of NPs stimulated SRB. This leads to oxidative stress response and structural damage to the cell membrane, which has emerged as the primary driver of the antibacterial action of Mg(OH)2 NPs. This study presents a novel nanomaterial that can inhibit and control SRB in natural sedimentary environments.

Genetic determinants of increased sodium hypochlorite and ciprofloxacin susceptibility in Pseudomonas aeruginosa PA14 biofilms

Reactive chlorine species (RCS) like sodium hypochlorite (NaOCl) are potent oxidizing agents and widely used biocides in surface disinfection, water treatment, and biofilm elimination. Moreover, RCS are also produced by the human immune system to kill invading pathogens. However, bacteria have developed mechanisms to survive the damage caused by RCS. Using the comprehensive Pseudomonas aeruginosa PA14 transposon mutant library in a genetic screen, we identified a total of 28 P. aeruginosa PA14 mutants whose biofilms showed increased susceptibility to NaOCl in comparison to PA14 WT biofilms. Of these, ten PA14 mutants with a disrupted apaH, PA0793, acsA, PA1506, PA1547, PA3728, yajC, queA, PA3869, or PA14_32840 gene presented a 4-fold increase in NaOCl susceptibility compared to wild-type biofilms. While none of these mutants showed a defect in biofilm formation or attenuated susceptibility of biofilms toward the oxidant hydrogen peroxide (H2O2), all but PA14_32840 also exhibited a 2–4-fold increase in susceptibility toward the antibiotic ciprofloxacin. Further analyses revealed attenuated levels of intracellular ROS and catalase activity only for the apaH and PA1547 mutant, providing insights into the oxidative stress response in P. aeruginosa biofilms. The findings of this paper highlight the complexity of biofilm resistance and the intricate interplay between different mechanisms to survive oxidative stress. Understanding resistance strategies adopted by biofilms is crucial for developing more effective ways to fight resistant bacteria, ultimately contributing to better management of bacterial growth and resistance in clinical and environmental settings.

Novel antioxidant peptides from sheep plasma protein hydrolysates: Purification, identification and cytoprotective effects against H2O2-induced oxidative stress.

This study sought to purify and identify antioxidant peptides from sheep (Ovis aries) plasma protein hydrolysates and assess their protective impacts on H2O2-induced Caco-2 cells. The purification process involved reversed high-performance liquid chromatography, anion-exchange chromatography, and Sephadex G-25. Three peptides, namely Trp-Glu-Glu-Pro-Ala-Met (WEEPAM), Ser-Leu-His-Phe-Met-Glu (SLHFME), and His-Cys-Thr-Thr-Phe-Met-Ile, with molecular weights of 761.84, 762.87, and 852.03Da, respectively, were identified by liquid chromatography with tandem mass spectrometry. Among the three antioxidant peptides, superoxide radical (O2 -) radical scavenging capacity of WEEPAM and SLHFME was not significantly different from glutathione (GSH) (p>0.05), while their 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity was greater than GSH (p<0.05). WEEPAM revealed increased antioxidant activity after pepsin and trypsin hydrolysis under an in vitro digestion model. In addition, WEEPAM inhibited oxidative damage in Caco-2 cells by significantly reducing reactive oxygen species accumulation, early apoptosis, malondialdehyde formation, and increasing intracellular superoxide dismutase, glutathione peroxidase, and catalase activities.

Neuroprotective Potential of Thunbergia laurifolia Lindl Leaf Extracts Against Beta Amyloid-induced Neurotoxicity: An in vitroModel of Alzheimer’s Disease

Background: Beta-amyloid peptide (Aβ) induces oxidative stress, contributing to Alzheimer’s disease (AD) initiation and progression. This study aims to explore Thunbergia laurifolia ( T. laurifolia) leaf extract’s protective effects on Aβ25–35-induced oxidative stress and cell injury in SH-SY5Y cells and investigate underlying mechanisms. Materials and Methods: SH-SY5Y cells were treated with T. laurifolia leaf extract in the presence or absence of Aβ25–35. After 24 h, neuroprotective effects were assessed using cell viability and lactate dehydrogenase (LDH) assays. Caspase-3/7 activity, intracellular reactive oxygen species (ROS) levels, catalase (CAT), and superoxide dismutase (SOD) activities were measured to examine mechanisms. Total flavonoid and phenolic content assays were performed. Results: The findings showed that exposure to Aβ25–35 led to a notable rise in oxidative stress in SH-SY5Y cells, as evidenced by increased levels of ROS. Additionally, Aβ25–35 treatment increased caspase-3/7 activity and LDH release and decreased cell viability. However, T. laurifolia extract effectively suppressed ROS production, attenuated caspase-3/7 activity, and concentration-dependently reduced Aβ25–35-induced neurotoxicity. LDH release decreased, and cell viability increased. SOD and CAT activities also increased after T. laurifolia treatment. The extract had total phenolic and flavonoid contents of 178.5 ± 6.86 and 32.51 ± 1.26 mg/g, respectively. Conclusion: T. laurifolia extract demonstrated neuroprotective effects against Aβ25–35-induced injury in SH-SY5Y cells. These effects were attributed to reduced oxidative stress, elevated SOD and CAT activity, and suppressed caspase-3/7 activity. T. laurifolia extract shows potential as an alternative or therapeutic approach to AD mediated by Aβ. Nevertheless, further research is needed to elucidate the mechanism by which T. laurifolia ameliorates neuronal cell death induced by Aβ25–35.

Ultrasmall Self-Cascade AuNP@FeS Nanozyme for H2S-Amplified Ferroptosis Therapy.

Recently, nanozymes with peroxidase (POD)-like activity have shown great promise for ferroptosis-based tumor therapy, which are capable of transforming hydrogen peroxide (H2O2) to highly toxic hydroxyl radicals (•OH). However, the unsatisfactory therapeutic performance of nanozymes due to insufficient endogenous H2O2 and acidity at tumor sites has always been a conundrum. Herein, an ultrasmall gold (Au) @ ferrous sulfide (FeS) cascade nanozyme (AuNP@FeS) with H2S-releasing ability constructed with an Au nanoparticle (AuNP) and an FeS nanoparticle (FeSNP) is designed to increase the H2O2 level and acidity in tumor cells via the collaboration between cascade reactions of AuNP@FeS and the biological effects of released H2S, achieving enhanced •OH generation as well as effective ferroptosis for tumor therapy. The cascade reaction in tumor cells is activated by the glucose oxidase (GOD)-like activity of AuNP in AuNP@FeS to catalyze intratumoral glucose into H2O2 and gluconic acid; meanwhile, the released H2S from AuNP@FeS reduces H2O2 consumption by inhibiting intracellular catalase (CAT) activity and promotes lactic acid accumulation. The two pathways synergistically boost H2O2 and acidity in tumor cells, thus inducing a cascade to generate abundant •OH by catalyzing H2O2 through the POD-like activity of FeS in AuNP@FeS and ultimately causing amplified ferroptosis. In vitro and in vivo experiments demonstrated that AuNP@FeS presents a superior tumor therapeutic effect compared to that of AuNP or FeS alone. This strategy represents a simple but powerful method to amplify ferroptosis with H2S-releasing cascade nanozymes and will pave a new way for the development of tumor therapy.

Effect of antioxidant and anti-inflammatory on bioactive components of carrot (Daucus carota L.) leaves from Jeju Island

The present study evaluated the potential of carrot (Daucus carota L.) leaf, a non-edible part of carrots, which are among the most consumed vegetables worldwide. The antioxidant activities of 70% ethanol extract (EEC) and hot water extract (HEC) of carrot leaves were compared. The results revealed that the total polyphenol content, total flavonoid content, and DPPH and ABTS radical scavenging activities were higher in EEC than in HEC. Both extracts protected the cells against H2O2-induced toxicity and markedly reduced the levels of reactive oxygen species in RAW 264.7 cells. Moreover, pretreatment of RAW 264.7 cells with EEC and HEC prior to H2O2 (500 μM) exposure increased superoxide dismutase and glutathione peroxidase activities in these cells. Notably, EEC and HEC increased intracellular catalase activity by 36.77 and 6.39 times, respectively. Compared to HEC, EEC remarkably inhibited the production of lipopolysaccharide-induced nitric oxide and reduced the gene expression of IL-6, IL-1β, iNOS, COX-2, and TNF-α. Comparative analysis of the composition of the extracts using HPLC–UV suggested notably higher contents of catechin, chlorogenic acid, caffeic acid, rutin, quercetin, and cynaroside in EEC than in HEC. Collectively, these results imply that carrot leaves are a potentially beneficial natural source of antioxidants and anti-inflammatory compounds in functional foods.

Reactive oxygen metabolism in the proliferation of Korean pine embryogenic callus cells promoted by exogenous GSH

Exogenous glutathione (GSH) promotes the proliferation of embryogenic callus (EC) cells in Korean pine in the course of somatic embryogenesis, and reactive oxygen species (ROS) may play an important role in regulating the proliferation of EC cells by exogenous GSH. However, the concrete metabolic response of ROS is unclear. In this study, two cell lines of Korean pine with high proliferative potential 001#-001 (F, Fast proliferative potential cell line is abbreviated as F) and low proliferative potential 001#-010 (S, Slow proliferative potential cell line is abbreviated as S) were used as test materials. The responses of ROS-related enzymes and substances to exogenous GSH and L-Buthionine-sulfoximine (BSO) were investigated in EC cells. The results showed that the exogenous addition of GSH increased the number of early somatic embryogenesis (SEs) in EC cells of both F and S cell lines, decreased the amount of cell death in both cell lines. Exogenous addition of GSH promoted cell division in both cell lines, increased intracellular superoxide dismutase (SOD) and catalase (CAT) activities, inhibited intracellular hydrogen peroxide (H2O2), malondialdehyde (MDA) and nitric oxide (NO) production, and increased NO/ROS ratio. In conclusion, the exogenous GSH promoting the proliferation of Korean pine EC cells, the activity of intracellular antioxidant enzymes was enhanced, the ROS level was reduced, and the resistance of cells to stress was enhanced.

Mitochondria-targeting Type I AIE photosensitizer combined with H2S therapy: Uninterrupted hydroxyl radical generation for enhancing tumor therapy

Although Type I photosensitizers with aggregation-induced emission (AIE) characteristics have thrived as alternative tools for cancer photodynamic therapy (PDT) thanks to their efficient reactive oxygen species (ROS) generation and hypoxia resistance, accumulated reducing substances sinside the tumor and the short lifespan of ROS limit their therapeutic effects. How to continuously generate long-lasting ROS in tumors remains a thorny problem. Herein, we constructed an uninterrupted ROS generator by incorporating the H2S donor, (NH4)2S, and a Type I AIE photosensitizer, TDCAc, into an injectable agarose hydrogel, namely TSH. Mitochondria-targeting TDCAc exhibited excellent performance in multi-model Type I photodynamic/photothermal therapy under near-infrared laser irradiation. While (NH4)2S generates H2S gas in the acidic tumor microenvironment upon photothermal dissolution of TSH gel, which diffuses into cancer cells and effectively inhibits intracellular catalase activity. Thus, the intrinsic H2O2 consumption pathway is blocked to promote endogenous labile iron pool-mediated continuous hydroxyl radical (·OH) generation in tumors. In both in vitro and in vivo experiments, uninterrupted massive production of·OH in cancer cells after laser irradiation of TSH gels was demonstrated. Notably, H2S gas therapy is firstly combined with Type I AIE PDT, affording a novel synergistic strategy of continuous·OH generation for boosting tumor therapy.

Controlling Specific Growth Rate for Recombinant Protein Production by Pichia pastoris Under Oxidation Stress in Fed-batch Fermentation.

Methanol can be used by Pichia pastoris as the carbon source and inducer to produce recombinant proteins in high-cell-density fermentations. However, methanol oxidation at high specific growth rates can lead to the reactive oxygen species (ROS) accumulation, resulting in cell damage. Here, we study the relationship between methanol feeding and ROS accumulation by controlling specific growth rate during the induction phase. A higher specific growth rate increased the level of ROS accumulation caused by methanol oxidation. While the cell growth rate was proportional to specific growth rate, maximum total protein production and highest enzyme activity were achieved at a specific growth rate of 0.05 1/h as compared to that of 0.065 1/h. Moreover, oxidative damage induced by over-accumulation of ROS in P. pastoris during the methanol induction phase caused cell death and reduced protein expression ability. ROS scavenging system analysis revealed that the higher specific growth rate, especially 0.065 1/h, resulted in increased intracellular catalase activity and decreased glutathione content significantly. Finally, Spearman's correlation analysis further revealed that the reduced glutathione might be beneficial for maintaining cell viability and increasing protein production under oxidative stress caused by ROS toxic accumulation. Our findings suggest an integrated strategy to control the feeding of the essential substrate based on analyzing its response to oxidative stress caused by ROS toxic accumulation, as well as develop a strategy to optimize fed-batch fermentation.

Plasma Transport Proteins in Patients with Tuberculosis and COVID-19 at the Stages of Treatment

The objective: to assess changes in the level of lactoferrin and ferritin in patients with pulmonary tuberculosis and COVID-19 during treatment, to determine their correlation with parameters of free radical oxidation and antioxidant protection.Subjects and methods. Levels of lactoferrin and erythrocyte catalase ferritin, neutrophil myeloperoxidase were studied against the background of successful treatment in the group of pulmonary tuberculosis patients (n = 80) and the group of COVID-19 patients (n = 75). Their correlation with parameters of free radical oxidation and antioxidant protection was assessed.Results. Before treatment, the median level of lactoferrin and ferritin increased in both groups, but in the COVID-19 Group, it was significantly more pronounced. At the end of the intensive phase in the Tuberculosis Group and when clinical improvement was achieved in the COVID-19 Group, the median ferritin level decreased. Increased myeloperoxidase activity and decreased level of erythrocyte catalase were also noted in both groups before treatment start; in the COVID-19 Group, the median level of myeloperoxidase was higher versus the Tuberculosis Group, which correlated with a higher median level of ferritin and lactoferrin in this group. After the end of the intensive phase of tuberculosis treatment and achievement of clinical improvement in COVID-19, there was a decrease in the median levels of myeloperoxidase, which coincided with a decrease in the levels of lactoferrin and ferritin. There was a direct strong correlation between myeloperoxidase-ferritin levels (r = 0.80; p &lt; 0.01) and myeloperoxidase-lactoferrin levels (r = 0.73; p &lt; 0.01). Against the background of treatment, intracellular catalase activity increased in both groups, almost reaching the normal value. Also, there is a strong inverse correlation between catalase and ferritin (r = -0.79; p &lt; 0.01).

Synergistic effect of docosahexaenoic acid or conjugated linoleic acid with caffeic acid on ameliorating oxidative stress of HepG2 cells.

Exploring the synergistic effect of docosahexaenoic acid (DHA) or conjugated linoleic acid (CLA) with caffeic acid (CA) on ameliorating oxidative stress, thereby introducing CA to DHA or CLA will contribute significantly to enhance the bioactivity. We observed that DHA or CLA with CA promoted the recovery of intact individual morphology and the decline of cavities inside the nucleus and apoptosis under the observation of confocal laser scanning microscopy and fluorescent inverted microscope. The activity of intracellular antioxidant enzymes catalase (CAT) and glutathione peroxidase (GSH-Px), lactate dehydrogenase (LDH) leakage, pyruvate and malondialdehyde and reactive oxygen species (ROS), cellular morphology, and cell cycle were analyzed. Our results showed that DHA or CLA with CA enhanced the activity of CAT and GSH-Px, decreased LDH leakage and the number of apoptotic, significantly inhibited (ROS-induced cellular injury. Cell arrest in G1 and G2 phase during cell mitosis was reduced by the measurement of flow cytometry. DHA or CLA combined with CA could markedly strengthen the free radical scavenging and endogenous antioxidant defense capacity on HepG2 cells. This study provides a new direction in the application of synergies to antioxidant compounds. PRACTICAL APPLICATION: Caffeic acid (CA) can synergize with docosahexaenoic acid (DHA) or conjugated linoleic acid (CLA) to enhance antioxidant capacity. This study highlighted an effect of ameliorating oxidative stress injury DHA or CLA with CA on HepG2 cells. The data indicated that DHA or CLA with CA might be used to relieve oxidative stress damage.

The Effects of Triclosan on Physiological and Photosynthetic Characteristics of Chlorella vulgaris

Triclosan has been widely used as addition ingredient in personal care and medical antibacterial products, and the increasing amounts of triclosan discharged in aquatic environments pose a potential risk to aquatic ecological systems. In this study, we investigated the effects of exposure to varying triclosan concentrations on the growth, chlorophyll fluorescence and antioxidant enzyme activity of Chlorella vulgaris. The results showed that low-concentration triclosan (&lt;0.75 mg/L) can stimulate the growth of Chlorella vulgaris, whereas 1.05 mg/L triclosan exhibited significant inhibition. Low-concentration triclosan (&lt;0.75 mg/L) could improve the tolerance and utilization ability of Chlorella vulgaris in relation to strong light. We observed a significant increase in the malondialdehyde content of Chlorella vulgaris exposed to 1.05 mg/L triclosan. The intracellular superoxide dismutase and catalase (CAT) activities of Chlorella vulgaris exposed to triclosan were higher than the control groups, and the increase in this activity was positively correlated with the concentration of triclosan. The results also showed that excessive H2O2 may in turn damage the CAT structure and eventually inactivate CAT activity when Chlorella vulgaris is exposed to 1.05 mg/L triclosan. This study provided a theoretical basis which can be used to evaluate the ecological risk of triclosan in the aquatic environment.

An in vitro and in silico study to explore the response of catalase to 4-chlorophenol and their interacting mechanisms

The present study conducted a novel strategy combining cellular and molecular methods to explore whether catalase (CAT) response is involved in 4-chlorophenol (4-CP) induced cytotoxicity and to investigate the detailed mechanism of CAT response to 4-CP. The results showed that the inhibition of CAT activity was not the primary cause of oxidative stress and cytotoxicity under 4-CP exposure. The decrease of intracellular CAT activity was contributed by the modulation of reactive oxygen species and the activity inhibition of CAT molecule. Isothermal titration calorimetry and molecular docking studies found that 4-CP binds to CAT with one binding site at the cavity between helical domain and threading arm majorly through van der Waals forces and hydrogen bonding. UV–vis absorption spectra showed that the binding unfolded the polypeptide chains of CAT and did not exhibit direct interruptions to heme groups around the active sites. Circular dichroism spectra found that the interaction caused secondary structure changes in CAT with a loss of α-helix content, which could be explained by the interaction of 4-CP with the residue HIS 62 in the binding site. Resonance light scattering spectra found that the aggregation state of CAT reduced under 4-CP exposure. These structural changes could influence the conformation around the active sites and then lead to the inhibition of molecular activity.

β-Glucan from Saccharomyces cerevisiae alleviates oxidative stress in LPS-stimulated RAW264.7 cells via Dectin-1/Nrf2/HO-1 signaling pathway.

β-Glucan from Saccharomyces cerevisiae has been described to be effective antioxidants, but the specific antioxidation mechanism of β-glucan is unclear. The objectives of this research were to determine whether the β-glucan from Saccharomyces cerevisiae could regulate oxidative stress through the Dectin-1/Nrf2/HO-1 signaling pathway in lipopolysaccharides (LPS)-stimulated RAW264.7 cells. In this study, we examined the effects of β-glucan on the enzyme activity or production of oxidative stress indicators in LPS-stimulated RAW264.7 cells by biochemical analysis and the protein expression of key factors of Dectin-1/Nrf2/HO-1 signaling pathway by immunofluorescence and western blot. The biochemical analysis results showed that β-glucan increased the LPS-induced downregulation of enzyme activity of intracellular heme oxygenase (HO), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) while decreasing the production of reactive oxygen species (ROS) and malondialdehyde (MDA). Furthermore, immunofluorescence results showed that β-glucan can activate the nuclear factor erythroid 2-related factor 2 (Nrf2). The antioxidant mechanism study indicated that β-glucan activated dendritic-cell-associated C-type lectin 1 (Dectin-1) receptors mediated Nrf2/HO-1 signaling pathway, thereby downregulating the production of ROS and thus produced the antioxidant effects in LPS-stimulated RAW 264.7 cells. In conclusion, these results indicate that β-glucan potently alleviated oxidative stress via Dectin-1/Nrf2/HO-1 in LPS-stimulated RAW 264.7 cells.

Supernatants of Bifidobacterium longum and Lactobacillus plantarum Strains Exhibited Antioxidative Effects on A7R5 Cells.

Vascular reactive oxygen species (ROS) play an essential role in cardiovascular diseases and the antioxidative effects of probiotics have been widely reported. To screen the probiotic strains that may prevent cardiovascular diseases, we tested the antioxidative effects of supernatants of different Bifidobacterium and Lactobacillus strains on A7R5 cells. Preincubation with supernatants of B. longum CCFM752, L. plantarum CCFM1149, or L. plantarum CCFM10 significantly suppressed the angiotensin II-induced increases in ROS levels and increased catalase (CAT) activity in A7R5, whereas CCFM752 inhibited NADPH oxidase activation and CCFM1149 enhanced the intracellular superoxide dismutase (SOD) activity simultaneously. Treatment with CCFM752, CCFM1149, or CCFM10 supernatants had no significant impact on transcriptional levels of Cat, Sod1, Sod2, Nox1, p22phox, or p47phox, but altered the overall transcriptomic profile and the expression of genes relevant to protein biosynthesis, and up-regulated the 60S ribosomal protein L7a (Rpl7a). A positive correlation between Rpl7a expression and intracellular CAT activity implied that Rpl7a may participate in CAT synthesis in A7R5. Supernatant of CCFM752 could also down-regulate the expression of NADPH oxidase activator 1 (Noxa1) and angiotensinogen in A7R5. Collectively, the probiotic strains CCFM752, CCFM1149, and CCFM10 exhibited antioxidative attributes on A7R5 cells and might help to reduce the risk of cardiovascular diseases.

Casein-maltodextrin Maillard conjugates encapsulation enhances the antioxidative potential of proanthocyanidins: An in vitro and in vivo evaluation

Practical application of proanthocyanidins (PAs) as antioxidants is limited because of their hard-to-maintained activities during the processes and storage and in severe gastrointestinal environments. To overcome this challenge, we have developed an easy and green method to encapsulate PAs based on casein-maltodextrin Maillard conjugates. The current work entails the systematic study on the antioxidative potentials of fabricated casein-maltodextrin-PAs nanoparticles (CMPNs). In vitro antioxidant activities of CMPNs remained well during storage in 28 days and treatments under 40–80 °C. In vivo Caenorhabditis elegans (C. elegans) model further showed that the CMPNs could prolong the lifespan of nematodes and protected nematodes from oxidative stress and heat shock. Analyses of intracellular superoxide dismutase and catalase activities also confirmed the existence of an antioxidant protective effect. Besides, in vitro release test showed that the encapsulation enhanced the bioaccessibility of PAs. These results have important implications for the development of novel antioxidants in nutraceutical industries.

Selenoprotein T protects against cisplatin-induced acute kidney injury through suppression of oxidative stress and apoptosis.

Previously, selenoprotein T (SelT) expression was shown to be induced in nervous, endocrine, and metabolic tissues during ontogeneticand regenerative processes. However, whether SelT plays a critical role in renal diseases remains unclear. Here, we explored the role of SelT in cisplatin-induced acute kidney injury (AKI). Results revealed that SelT was highly expressed in renal tubules, but its expression was significantly reduced in cisplatin-induced AKI. Importantly, knocking down of SelT expression in kidney cells in vitro resulted in cisplatin-induced cell apoptosis, as indicated by the elevation of cleaved-PARP and Bax expression, Caspase-3 activity, and number of TUNEL-positive cells. Moreover, SelT silencing-induced reactive oxygen species (ROS) production, accompanied by a decrease in intracellular superoxide dismutase (SOD) and catalase (CAT) activity and increase in malondialdehyde (MDA) content. Notably, the protein and mRNA levels of Nox4 were increased in response to SelT downregulation. Furthermore, suppression of Nox4 expression by GKT137831 partially alleviated SelT knockdown-induced ROS generation and cell apoptosis in cisplatin-treated kidney cells. Taken together, our findings provide the first evidence that SelT protects against cisplatin-induced AKI by suppression of oxidative stress and apoptosis.

Chitosan-Functionalized Graphene Nanocomposite Films: Interfacial Interplay and Biological Activity.

Graphene oxide (GO) has recently captured tremendous attention, but only few functionalized graphene derivatives were used as fillers, and insightful studies dealing with the thermal, mechanical, and biological effects of graphene surface functionalization are currently missing in the literature. Herein, reduced graphene oxide (rGO), phosphorylated graphene oxide (PGO), and trimethylsilylated graphene oxide (SiMe3GO) were prepared by the post-modification of GO. The electrostatic interactions of these fillers with chitosan afforded colloidal solutions that provide, after water evaporation, transparent and flexible chitosan-modified graphene films. All reinforced chitosan–graphene films displayed improved mechanical, thermal, and antibacterial (S. aureus, E. coli) properties compared to native chitosan films. Hemolysis, intracellular catalase activity, and hemoglobin oxidation were also observed for these materials. This study shows that graphene functionalization provides a handle for tuning the properties of graphene-reinforced nanocomposite films and customizing their functionalities.

In vitro toxicity and molecular interacting mechanisms of chloroacetic acid to catalase.

Chloroacetic acid (CAA), one of typical disinfection by-products (DBPs), has attracted considerable concerns for its biological safety. Antioxidant enzyme catalase (CAT) plays a crucial part in the regulation of redox state balance. Herein, CAA was used to test its adverse effects on CAT and explore the underlying mechanism. The cell viability of mouse primary hepatocytes decreased under CAA exposure. A bell-shaped response to CAA exposure was observed in intracellular CAT activity, whose change was partly influenced by molecular CAT activity. CAA binds to CAT mainly via van der Waals forces and hydrogen bonds with a stoichiometry of 9.2. The binding caused structural changes in CAT with the unfolding of polypeptide chains and the decrease of α-helical content. CAA interacts with the amino acid residues surrounding the active sites and substrate channel of CAT. These interactions result in the decrease of molecular CAT activity, which could be restored by high ionic strength. This study has provided a combined molecular and cellular tactics for studying the adverse effects of DBPs on biomarkers and the underlying mechanisms.

184 Effects of cyanidin supplementation on invitro maturation of pig oocytes

Oxidative stress can have a negative effect on oocyte maturation during invitro production of pig embryos. Imbalance of reactive oxygen species and antioxidant levels can affect the progression of oocyte maturation up to the point of fertilization. Antioxidants are effective in maintaining more ideal reactive oxygen species levels, which help to protect oocytes from potential harmful effects of oxidative stress. Berries from the elder plant (Sambucus sp.) contain high levels of a broad spectrum of antioxidants. One of these antioxidants, cyanidin, when supplemented to maturation medium at 100μM concentrations, reduces reactive oxygen species formation and improves IVF and early embryonic development in pigs. However, changes in the enzyme mechanisms of action during oocyte maturation due to cyanidin supplementation are unknown. Therefore, the objective of this study was to characterise the intracellular oocyte enzyme mechanisms between oocytes supplemented with 100μM cyanidin during 40 to 44h of maturation (n=600) and oocytes without supplementation of cyanidin during maturation (n=558). At the end of maturation, oocytes were evaluated for either glutathione peroxidase (n=300), catalase (n=564), or superoxide dismutase (n=294) activities. Glutathione peroxidase activity was determined by following the rate of NADPH oxidation, catalase activity was determined by following the rate of hydrogen peroxide decomposition, and superoxide dismutase activity was determined by following the reduction rate of cytochrome c, utilising the xanthine-xanthine oxidase system. Data were analysed using ANOVA and Tukey's test. There were no significant differences between oocytes matured with 100μM cyanidin and those that were not when comparing glutathione peroxidase and superoxide dismutase activities. Supplementation of 100μM cyanidin to maturation medium increased (P&amp;lt;0.05) catalase activity in oocytes (0.78±0.15 units/oocyte) compared with no cyanidin supplementation (0.14±0.11 units/oocyte). These results indicate that supplementing 100μM cyanidin to the maturation medium of pig oocytes could reduce the negative effects of oxidative stress by increasing intracellular catalase activity during oocyte maturation.