Study of pesticidal activity of bioactive compounds of Neowestiellopsis persica strain A1387 in improving the antioxidative and antimicrobial activity of wheat to sunn pest.

Cyanobacteria have been recognized for their advantageous impact on plant growth and development. The application of certain techniques has the potential to enhance various aspects of plant development, including growth, yield, proximate content (such as protein and carbohydrate levels), as well as the ability to withstand abiotic stresses such as herbicide exposure. The current investigation focused on examining the influence of bioactive compounds derived from the cyanobacterium Neowestiellopsis persica strain A1387 on enhancing the antioxidant and anyimicrobial activity of wheat plants in their defense against the plant pathogenic Sunn pest. The findings of the study indicate that the levels of H2O2 and GPx in wheat plants that were infected with aphids were significantly elevated compared to the treatments where aphids and cyanobacteria extract were present. The confirmation of these results was achieved through the utilization of confocal and fluorescent microscope tests, respectively. Furthermore, the findings indicated that the constituents of the cyanobacterial extract augmented the plant's capacity to withstand stress by enhancing its defense mechanisms. In a broader context, the utilization of cyanobacterial extract demonstrated the ability to regulate the generation and impact of oxygen (O2) and hydrogen peroxide (H2O2), while concurrently enhancing the functionality of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) enzymes within wheat plants. This facilitation enabled the plants to effectively manage oxidative stress. Moreover, the findings of the antibacterial activity assessment conducted on the extract derived from cyanobacteria demonstrated notable susceptibility. The bacteria that exhibited the highest sensitivity to the extract of cyanobacterium Neowestiellopsis persica strain A1387 were staphylococcus aureus and pseudomonas aeruginosa. Conversely, salmonella typhi demonstrated the greatest resistance to the aforementioned extract. The potential impact of cyanobacteria extract on the antioxidative response of wheat plants to sunn pest infestation represents a novel contribution to the existing body of knowledge on the interaction between wheat plants and aphids.

Anti-Inflammatory Activity of Cyanobacteria Pigment Extracts: Physiological Free Radical Scavenging and Modulation of iNOS and LOX Activity.

Cyanobacteria are among the oldest organisms colonizing Earth. Their great biodiversity and ability to biosynthesize secondary metabolites through a variety of routes makes them attractive resources for biotechnological applications and drug discovery. In this pioneer study, four filamentous cyanobacteria (Cephalothrix lacustris LEGE 15493, Leptolyngbya boryana LEGE 15486, Nodosilinea nodulosa LEGE 06104 and Leptothoe sp. LEGE 11479) were explored for their anti-inflammatory potential in cell and cell-free in vitro bioassays, involving different inflammatory mediators and enzymes. Extracts of different polarities were sequentially prepared and chemically characterized for their content of phycobiliproteins (PBPs) and carotenoids. HPLC-PDA analysis of the acetone extracts revealed ß-carotene to be the dominant carotenoid (18.4-44.3 mg/g) and zeaxanthin as the dominant xanthophyll (52.7-192.9 mg/g), with Leptothoe sp. LEGE 11479 and Nodosilinea nodulosa LEGE 06104, respectively, being the richest strains. The PBP profile was in accordance with the color presented by the aqueous extracts, with Leptolyngbya boryana LEGE 15486 being the richest in phycocyanin (204.5 µg/mg) and Leptothoe sp. LEGE 11479 the richest in phycoerythrin (78.5 µg/mg). Aqueous extracts were more effective in superoxide anion radical scavenging, while acetone ones were more effective in scavenging nitric oxide radical (●NO) and in inhibiting lipoxygenase. Acetone extracts also reduced ●NO production in lipopolysaccharide-stimulated RAW 264.7 macrophages, with the mechanistic study suggesting a downregulation of the inducible nitric oxide synthase expression. Nodosilinea nodulosa LEGE 06104 and Leptothoe sp. LEGE 11479 acetone extracts presented the lowest IC50 values for the mentioned assays, pointing them out as promising resources for the development of new multi-target anti-inflammatory therapies.

Molecular Dynamics Study of the Effect of Charge and Glycosyl on Superoxide Anion Distribution near Lipid Membrane.

To examine the effects of membrane charge, the electrolyte species and glycosyl on the distribution of negatively charged radical of superoxide anion (·O2-) around the cell membrane, different phospholipid bilayer systems containing ·O2- radicals, different electrolytes and phospholipid bilayers were constructed through Charmm-GUI and Amber16. These systems were equilibrated with molecular dynamics by using Gromacs 5.0.2 to analyze the statistical behaviors of ·O2- near the lipid membrane under different conditions. It was found that in the presence of potassium rather than sodium, the negative charge of the phospholipid membrane is more likely to rarefy the superoxide anion distribution near the membrane surface. Further, the presence of glycosyl significantly reduced the density of ·O2- near the phospholipid bilayer by 78.3% compared with that of the neutral lipid membrane, which may have a significant contribution to reducing the lipid peroxidation from decreasing the ·O2- density near the membrane.

Regulation of the generation of reactive oxygen species during photosynthetic electron transport.

Light capture by chlorophylls and photosynthetic electron transport bury the risk of the generation of reactive oxygen species (ROS) including singlet oxygen, superoxide anion radicals and hydrogen peroxide. Rapid changes in light intensity, electron fluxes and accumulation of strong oxidants and reductants increase ROS production. Superoxide is mainly generated at the level of photosystem I while photosystem II is the main source of singlet oxygen. ROS can induce oxidative damage of the photosynthetic apparatus, however, ROS are also important to tune processes inside the chloroplast and participate in retrograde signalling regulating the expression of genes involved in acclimation responses. Under most physiological conditions light harvesting and photosynthetic electron transport are regulated to keep the level of ROS at a non-destructive level. Photosystem II is most prone to photoinhibition but can be quickly repaired while photosystem I is protected in most cases. The size of the transmembrane proton gradient is central for the onset of mechanisms that protect against photoinhibition. The proton gradient allows dissipation of excess energy as heat in the antenna systems and it regulates electron transport. pH-dependent slowing down of electron donation to photosystem I protects it against ROS generation and damage. Cyclic electron transfer and photoreduction of oxygen contribute to the size of the proton gradient. The yield of singlet oxygen production in photosystem II is regulated by changes in the midpoint potential of its primary quinone acceptor. In addition, numerous antioxidants inside the photosystems, the antenna and the thylakoid membrane quench or scavenge ROS.

Tissue-Engineered Constructions in Biophysics, Neurology and Other Fields and Branches of Medicine.

This paper describes the gangliopexy method, a method for creating a new center of local neurohumoral regulation, based on the formation of new connections discovered between the nervous system and the vascular system. The prospects for the development of this method are studied. At the same time, novel concepts about the cycles of nitric oxide and the superoxide anion radical are introduced. A possible role of these cycles is examined in the protection of cells and the body as a whole against oxidative and nitrosative stress, which develops when (in 5-30% of cases) destructive changes in the displaced ganglion lead to vascular complications and an increased risk of mortality. Mechanisms that can protect nerve cells, prevent the development of destructive changes in these cells and reduce the risk of mortality are also investigated.

Synergistic properties of bioavailable phenolic compounds from olive oil: electron transfer and neuroprotective properties.

Phenolic compounds from olive oil (ArOH-EVOO) are recognized for their antioxidant and neuroprotective capacities, but are often studied individually or through a natural extract. As their reactivity towards reactive oxygen species (ROS) depends on their structure and could implicate different complementary mechanisms, we hypothesized that their effects could be enhanced by an innovative combination of some of the most abundant ArOH-EVOO. Using electrochemical methods, we have compared their reactivity towards hydrogen peroxide and the superoxide anion radical. The mixture containing oleuropein, p-coumaric acid and tyrosol (Mix1), was more efficient than the mixture containing hydroxytyrosol, the oleuropein catechol moiety, and the two monophenols (Mix2). On neuronal SK-N-SH cells challenged with H2O2 or Paraquat, low concentrations (0.1 and 1 µM) of the Mix1 improved neuronal survival. These neuroprotective effects were supported by a decrease in intracellular ROS, in the protein carbonyl levels and the prevention of the redox-sensitive factors Nrf2 and NF-κB activation. These intracellular effects were supported by the demonstration of the internalization of these ArOH-EVOO into neuronal cells, evidenced by LC-HRMS. Our results demonstrated that this combination of ArOH-EVOO could be more efficient than individual ArOH usually studied for their neuroprotective properties. These data suggest that the Mix1 could delay neuronal death in neurodegenerative diseases related to oxidative stress such as Alzheimer's (AD) and Parkinson's diseases (PD).

Structural Features of Cytochrome b5-Cytochrome b5 Reductase Complex Formation and Implications for the Intramolecular Dynamics of Cytochrome b5 Reductase.

Membrane cytochrome b5 reductase is a pleiotropic oxidoreductase that uses primarily soluble reduced nicotinamide adenine dinucleotide (NADH) as an electron donor to reduce multiple biological acceptors localized in cellular membranes. Some of the biological acceptors of the reductase and coupled redox proteins might eventually transfer electrons to oxygen to form reactive oxygen species. Additionally, an inefficient electron transfer to redox acceptors can lead to electron uncoupling and superoxide anion formation by the reductase. Many efforts have been made to characterize the involved catalytic domains in the electron transfer from the reduced flavoprotein to its electron acceptors, such as cytochrome b5, through a detailed description of the flavin and NADH-binding sites. This information might help to understand better the processes and modifications involved in reactive oxygen formation by the cytochrome b5 reductase. Nevertheless, more than half a century since this enzyme was first purified, the one-electron transfer process toward potential electron acceptors of the reductase is still only partially understood. New advances in computational analysis of protein structures allow predicting the intramolecular protein dynamics, identifying potential functional sites, or evaluating the effects of microenvironment changes in protein structure and dynamics. We applied this approach to characterize further the roles of amino acid domains within cytochrome b5 reductase structure, part of the catalytic domain, and several sensors and structural domains involved in the interactions with cytochrome b5 and other electron acceptors. The computational analysis results allowed us to rationalize some of the available spectroscopic data regarding ligand-induced conformational changes leading to an increase in the flavin adenine dinucleotide (FAD) solvent-exposed surface, which has been previously correlated with the formation of complexes with electron acceptors.

Rapid screening and evaluation of XOD inhibitors and O2 •- scavenger from total flavonoids of Ginkgo biloba leaves by LC-MS and multimode microplate reader.

Superoxide anion radical scavenger and xanthine oxidase inhibitor play an important role in the treatment of several relevant human diseases. In the present study, ultrafiltration liquid chromatography-mass spectrometry coupled to microplate reader was applied to screen and identify superoxide anion radical scavengers and xanthine oxidase inhibitors from total flavonoids of Ginkgo biloba leaves. As a result, four compounds (quercetin, apigenin, kaempferol and isorhamnetin) were screened as xanthine oxidase inhibitors by ultrafiltration LC-MS, and the 50% scavenging concentration values of the screened flavonoids were lower than those for allopurinol. Lineweaver-Burk plot results indicated that kaempferol was a competitive xanthine oxidase inhibitor; the other flavonoids were all anticompetitive inhibitors. Four flavonoids-rutin, quercetin, kaempferol and isorhamnetin-were screened as superoxide anion radical scavengers by LC-MS. The results demonstrate that the method for screening and evaluation of superoxide anion radical scavenger and xanthine oxidase inhibitor from a complex mixture system is feasible and efficient.

Catechin Photolysis Suppression by Aluminum Chloride under Alkaline Conditions and Assessment with Liquid Chromatography-Mass Spectrometry.

Tea is rich in catechins and aluminum. In this study, the process of catechin photolysis was applied as a model for examining the effects of aluminum chloride (AlCl3) on the structural changes of catechin and the alteration of aluminum complexes under blue light irradiation (BLI) at pH 8 using liquid chromatography and mass spectrometry techniques. Additionally, the effects of anions on catechin upon the addition of AlCl3 and treatment with BLI were also studied. In this study, when 1 mM catechin was treated with BLI, a superoxide anion radical (O2•-) was generated in an air-saturated aqueous solution, in addition to forming a dimeric catechin (proanthocyanidin) via a photon-induced redox reaction. The relative percentage of catechin was found to be 59.0 and 95.7 for catechin treated with BLI and catechin upon the addition of 1 mM AlCl3 treated with BLI, respectively. It suggested that catechin treated with BLI could be suppressed by AlCl3, while AlCl3 did not form a complex with catechin in the photolytic system. However, under the same conditions, it was also found that the addition of AlCl3 inhibited the photolytic formation of O2•-, and reduced the generation of proanthocyanidin, suggesting that the disconnection of proanthocyanidin was achieved by AlCl3 acting as a catalyst under treatment with BLI. The influence of 1 mM fluoride (F-) and 1 mM oxalate (C2O42-) ions on the photolysis of 1 mM catechin upon the addition of 1 mM AlCl3 and treatment with BLI was found to be insignificant, implying that, during the photolysis of catechin, the Al species were either neutral or negatively charged and the aluminum species did not form a complex with anions in the photolytic system. Therefore, aluminum, which is an amphoteric species, has an inherent potential to stabilize the photolysis of catechin in an alkaline conditions, while suppressing the O2•- and proanthocyanidin generation via aluminum ion catalysis in the catechin/Al system under treatment with BLI.

Design, synthesis and photoinduced DNA cleavage studies of [1,2,4]-triazolo[4,3-a]quinoxalin-4(5H)-ones.

An expedient and eco-friendly synthesis of 1-aryl/heteroaryl-[1,2,4]-triazolo[4,3-a]quinoxalin-4(5H)-ones (4) has been accomplished via iodobenzene diacetate mediated oxidative intramolecular cyclization of 3-(2-(aryl/heteroarylidene)hydrazinyl)-quinoxalin-2(1H)-ones (3). Ten synthesized compounds 3 and 4 (10-40 µg) on irradiation with UV light at λmax 312 nm could lead to cleavage of supercoiled pMaxGFP DNA (Form I) into the relaxed DNA (Form II) without any additive. Further, DNA cleaving ability of triazoles was quantitatively evaluated and was found to be dependent on its structure, concentration, and strictly on photoirradiation time. Mechanistic investigations using several additives as potential inhibitors/activator revealed that the DNA photocleavage reaction involves Type-I pathway leading to formation of superoxide anion radicals (O2-) as the major reactive oxygen species responsible for photocleavage process.

Detection of synergistic effect of superoxide dismutase and jujubosides on scavenging superoxide anion radical by capillary electrophoresis.

A new capillary electrophoresis method was developed to study the synergistic effect of superoxide dismutase and jujuboside A or B on scavenging superoxide anion radical in serum matrix respectively, in which superoxide anion radical was generated from pyrogallol autoxidation. The electrophoresis conditions, and the factors affecting the productive rate of purpurogallin, such as pyrogallol autoxidation product and the activity of superoxide dismutase, were optimized. Under optimal conditions, the content of superoxide dismutase in Gibco newborn calf serum was 7.06 mg/L, RSD was 2.01% and the average recovery was 98.4%. The values of IC50 for jujuboside A and B in the serum matrix were 157.67 and 31.60 mg/L respectively, and they both had synergy on scavenging superoxide anion radical with superoxide dismutase, but there was no the dose-dependency on this synergy.

[Effect of essential lipophilic nutrients on free radical processes in liver mitochondrial fraction of the tumor-bearing rats].

Oxidative stress is a universal mechanism of cellular damage of hepatocytes, leading to a decrease in the detoxification function of the liver, which is especially important during oncogenesis. An early correction of these mechanisms by lipophilic essential nutrients could increase the effectiveness of antitumor treatment and prevent the development and progress of cancer. Aim to study the effect of separate and combined use of ω-3 PUFA and vitamin D3 on the intensity of free radical processes, mitochondrial swelling and cytochrome c content in the liver mitochondrial fraction of the tumor-bearing rats during the intensive growth of the tumor has been studied. Material and methods. Studies were carried out on white outbred female rats weighing 130-150 g, which were divided into 5 groups (each n=12). Guerin's carcinoma was used as a model of malignant neoplasm. Carcinoma transplantation was carried out by subcutaneous injection of 0.5 ml of a 30% suspension of cancer cells into saline in the upper thigh region of the right limb. ω-3 PUFAs (120 mg/kg of body weight, per os) and vitamin D3 (600 IU/kg of body weight, per os) were pre-administered for 28 days before the transplantation of Guerin's carcinoma and after transplantation for the entire period of tumor growth in the body (14 days). Liver mitochondrial fraction was isolated by differential centrifugation. The intensity of lipid peroxidation was judged by using spectrophotometry by the content of primary, secondary, and tertiary products in isopropanol extracts. The rate of formation of the superoxide radical was recorded in a test with nitro-blue tetrazolium, the swelling of mitochondria was assessed by a decrease in the optical density of isolated mitochondria, the content of cytochrome c in the mitochondrial and cytosolic fractions was determined by multi-wavelength visible light spectroscopy. Results and discussion. An increase in the content of primary (diene and triene conjugates), secondary (ketodienes; conjugated trienes; TBA-active products) and terminal (Schiff bases) lipid peroxidation products with a simultaneous increase in the generation of superoxide anion-radical was found in the liver mitochondrial fraction of the tumorbearing rats. With the administration of ω-3 PUFA and vitamin D3, both separately and especially when used together, a decrease in the intensity of free radical processes in liver mitochondrial fraction of tumor-bearing rats has been observed. At the same time, mitochondrial swelling decreased, this prevented the release of cytochrome c from mitochondria into cytosol. Conclusion. The administration of the complex ω-3 PUFA and vitamin D3 reduces the processes of lipid peroxidation in the mitochondrial fraction of the liver of tumor-bearing rats while simultaneously restoring the functional ability of mitochondria.

2-(2-Nitrovinyl) furan exacerbates oxidative stress response of Escherichia coli to bacteriostatic and bactericidal antibiotics.

The influence of 2-(2-nitrovinyl) furan on the activities of selected bacteriostatic and bactericidal antibiotics was investigated. Minimum inhibitory concentration and fractional inhibitory concentration index were determined to evaluate the interaction between 2-(2-nitrovinyl) furan and the antibiotics. 2-(2-nitrovinyl) furan exhibited additive interactions with chloramphenicol, erythromycin, lincomycin and gemifloxacin. However, synergistic interaction was observed with amoxicillin, ampicillin and ciprofloxacin. Superoxide anion content of Escherichia coli exposed to antibiotics with/without 2-(2-nitrovinyl) furan increased significantly (p < .05). Furthermore, reduced glutathione decreased significantly with a corresponding increase in glutathione disulphide. In addition, malondialdehyde, a product of lipid peroxidation, increased significantly in E. coli exposed to antibiotics and 2-(2-nitrovinyl) furan. It can be deduced from this study that 2-(2-nitrovinyl) furan enhanced bacteriostatic and bactericidal antibiotics-mediated bacterial death possibly by potentiating reactive oxygen species generation and oxidative stress.

Demethoxycurcumin mediated targeting of MnSOD leading to activation of apoptotic pathway and inhibition of Akt/NF-κB survival signalling in human glioma U87 MG cells.

Earlier, we reported that Demethoxycurcumin (DMC) suppressed the growth of human glioma U87 MG cells by downregulation of Bcl-2 expression. In the present work, we investigated the DMC induced reactive oxygen species (ROS) mediated anti-proliferative and apoptotic effects in U87 MG cells. Exposure of U87 MG cells to growth-suppressive concentrations of DMC (0-50 µg/ml) resulted in ROS generation and concomitant increase in apoptosis. The major oxidative species induced by DMC was superoxide anion radical (O2-). DMC-induced anti-proliferation was mediated by Akt/NF-κB signalling inhibition and apoptosis through caspase-8 and 9 activation. In silico molecular docking analysis showed that, the amino acid residues His30, Tyr34, Asn37, Ala63, Asn67, His74, Trp123, and Asp159 in the active site of mitochondrial SOD (MnSOD) interacted with DMC. Furthermore, the complex MnSOD-DMC was found to be more stable as compared to native MnSOD in the MD simulations. In the present study, we have demonstrated for the first time using U87 MG cell line that DMC (a) establishes π-π interactions with Tyr 34 and Trp 161 in the putative active site of MnSOD to inhibit its activity, generating (O2-) to regulate survival and apoptotic proteins leading to antiproliferative and apoptotic events (b) induces antiproliferative effect via inhibition of Akt/NF-κB signalling pathway (c) contributes to the apoptosis via caspase-8 and caspase-9 activation to release the cytochrome c. In exploring the DMC induced cell death events in U 87 MG cell line, we revealed a novel mechanism of DMC-mediated inhibition of MnSOD leading to accumulation of superoxide anions to trigger the inhibition of survival pathways and induction of apoptosis.

Unique antioxidant effects of herbal leaf tea and stem tea from Moringa oleifera L. especially on superoxide anion radical generation systems.

This study aimed to investigate the unique antioxidative effects of Japanese moringa products, herbal leaf tea and stem tea, using established free radical assays, focusing on superoxide anion (O2-) radical generation systems. Hot-water extracts from moringa teas resulted in different but lower scavenging activities than Trolox in four synthetic free radical models. Interestingly, these extracts further showed higher O2- radical scavenging effects than Trolox in the phenazine methosulfate-NADH-nitroblue tetrazolium and xanthine oxidase assay systems. Incubating human neutrophils in the presence of these tea extracts rather than Trolox effectively suppressed cellular O2- radical generation. Among the eight known phenolic constituents of moringa leaves, caffeic acid and chlorogenic acid may be responsible for the O2-specific radical scavenging capacity stronger than that of Trolox. These results suggest that moringa herbal teas are a good source of natural antioxidants for preventing O2- radical-mediated disorders. Abbreviations: O2-: superoxide anion; ROS: reactive oxygen species; H2O2: hydrogen peroxide; XOD: xanthine oxidase; DPPH: 1,1-diphenyl-2-picrylhydrazyl; ABTS+: 2,2'-azinobis(2-ethylbenzothiazoline-6-sulfonic acid) cation; CPZ+: chlorpromazine cation; PMS: phenazine methosulfate; NBT: nitroblue tetrazolium; PMA: phorbol 12-myristate 13-acetate.

Influence of oxidative stress on the antibacterial activity of betulin, betulinic acid and ursolic acid.

Contribution of reactive oxygen species and oxidative stress in the antibacterial activities of betulin, betulinic acid and ursolic acid against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus was investigated. The minimum inhibitory concentrations of betulin, betulinic acid and ursolic acid against E. coli, P. aeruginosa and S. aureus are 1024-, 256- and 1024-µg/mL; 512-, 256- and 256 µg/mL; 256-, 256- and 64 µg/mL respectively. Cell viability of betulin-, betulinic acid- and ursolic acid-treated bacteria decrease in time dependent manner. Treatment of bacteria in the presence of 2,2'-bipyrydyl increased cell viability. Superoxide anion radical production increased significantly (p < 0.05) in bacterial cells-treated with betulin, betulinic acid and ursolic acid. Furthermore, NAD+/NADH ratio increased significantly (p < 0.05) in betulin-, betulinic acid- and ursolic acid-treated bacteria. Similarly, level of reduced glutathione in E. coli, P. aeruginosa and S. aureus decreased significantly with corresponding increase in glutathione disulphide, malondialdehyde and fragmented DNA following betulin, betulinic acid and ursolic acid treatments. It is evident from the above findings that betulin, betulinic acid and ursolic acid enhanced electron transport chain activity in E. coli, P. aeruginosa and S. aureus leading to increased ROS generation, Fenton reaction, lipid peroxidation, fragmented DNA and consequentially bacterial death.

Automated image analysis for quantification of reactive oxygen species in plant leaves.

The paper presents an image processing method for the quantitative assessment of ROS accumulation areas in leaves stained with DAB or NBT for H2O2 and O2- detection, respectively. Three types of images determined by the combination of staining method and background color are considered. The method is based on the principle of supervised machine learning with manually labeled image patterns used for training. The method's algorithm is developed as a JavaScript macro in the public domain Fiji (ImageJ) environment. It allows to select the stained regions of ROS-mediated histochemical reactions, subsequently fractionated according to the weak, medium and intense staining intensity and thus ROS accumulation. It also evaluates total leaf blade area. The precision of ROS accumulation area detection is validated by the Dice Similarity Coefficient in the case of manual patterns. The proposed framework reduces the computation complexity, once prepared, requires less image processing expertise than the competitive methods and represents a routine quantitative imaging assay for a general histochemical image classification.

Redox and respiratory chain related alterations in the lophirones B and C-mediated bacterial lethality.

The influence of chalcone dimers, lophirones B and C on redox status and respiratory chain activity of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa was investigated. Minimum inhibitory concentrations (MIC) of lophirones B and C against E. coli, P. aeruginosa and S. aureus are 200-; 100-; 200- and 150-µg/mL respectively. Similarly, the minimum bactericidal concentrations (MBC) of lophirones B and C are 250; 200; 300 and 200-µg/mL respectively. The optical densities and colony forming units of lophirones B and C-treated bacteria decreased in time-dependent manner. Superoxide anion content of E. coli, P. aeruginosa and S. aureus exposed to lophirones B and C (4× MIC) increased significantly. Superoxide dismutase and catalase in the chalcone dimers-treated bacteria increased significantly. Conversely, reduced glutathione in lophirones B and C-treated bacteria decrease significantly with corresponding increase in glutathione disulfide. Furthermore, malondialdehyde and fragmented DNA increased significantly following exposure to the chalcone dimers. The respiratory complex I and II decreased significantly in the chalcone dimers-treated bacteria. From the findings, lophirones B and C altered intracellular redox status via enhanced oxidant generation possibly by autoxidation, Fenton chemistry and inhibiting electron transport chain resulting to lipid peroxidation and DNA fragmentation and consequentially bacterial cell death.

Fabrication of photo-induced molecular superoxide radical generator for highly efficient therapy against bacterial wound infection.

The pressing need for highly efficient antibacterial strategies arises from the prevalence of microbial biofilm infections and the emergence of rapidly evolving antibiotic-resistant strains of pathogenic bacteria. Photodynamic therapy represents a highly efficient and compelling antibacterial approach, offering promising prospects for effective control of the development of bacterial resistance. However, the effectiveness of many photosensitizers is limited due to the reduced generation of reactive oxygen species (ROS) in hypoxic microenvironment, which commonly occur in pathological conditions such as inflammatory and bacteria-infected wounds. Herein, we designed and prepared two phenothiazine-derived photosensitizers (NB-1 and NB-2), which can effectively generate superoxide anion radicals (O2●-) through the type I process. Both photosensitizers demonstrate significant efficacy in vitro for the eradication of broad-spectrum bacteria. Moreover, NB-2 possesses distinct advantages including strong membrane binding and strong generation of O2●-, rendering it an exceptionally efficient antibacterial agent against mature biofilms. In addition, laser activated NB-2 could be applied to treat MRSA-infected wound in vivo, which offers new opportunities for potential practical applications.

Evaluation of nanoplastics-induced redox imbalance in cells, larval zebrafish, and daphnia magna with a superoxide anion radical fluorescent probe.

Nanoplastics (NPs) is a novel plastic contaminant that could be taken up by cells and lead to severe biotoxicity toxicity, NPs in cells can cause oxidant damage by inducing reactive oxygen species (ROS) production and lead to acute inflammation. As a major ROS which related to many kinds of physiological and pathological processes, superoxide anion radical (O2•-) could be utilized as a signal of oxidant damage effected by NPs exposure in vivo. To detect the toxic damage mechanism of NPs, a fluorescence probe Bcy-OTf has been developed to monitor O2•- fluctuations content in cells and aquatic organisms after exposure to NPs. The probe has a high sensitivity (LOD = 20 nM) and a rapid responsive time (within 6 min), and it has high selectivity and low cytotoxicity to analysis the levels of the endogenous O2•-. Endogenous O2•- induced by NPs in living cells, Daphnia magna and larval zebrafish were analyzed. Moreover, the results confirmed the key role of MAPK and NF-κB pathway in NPs stimulation mechanisms in cells. This study indicated that Bcy-OTf can precisely assess the fluctuations of endogenous O2•-, which has potential for applying in further analysis mechanisms of NPs biological risks.