ROS Burst Research Articles

Characterization of Five Meloidogyne incognita Effectors Associated with PsoRPM3.

Root-knot nematodes (RKNs) are devastating parasites that invade thousands of plants. In this study, five RKN effectors, which might interact with Prunus sogdiana resistance protein PsoRPM3, were screened and identified. In situ hybridisation results showed that MiCal, MiGST_N_4, MiEFh and MiACPS are expressed in the subventral oesophageal glands (SvG), and MiTSPc hybridization signals are found in the dorsal esophageal gland (DG) of Meloidogyne incognita in the pre-J2. RT-qPCR data indicated that the expression of MiCal, MiGST_N_4, MiEFh, and MiACPS genes are highly expressed in M. incognita of pra-J2 and J3/J4 stages. The expression of MiTSPc increased significantly in the female stage of M. incognita. Moreover, all effectors found in this study localize in the cytoplasm and nucleus when transiently expressed in plant cells. In addition, MiGST_N_4, MiEFh, MiACPS and MiTSPc can elicit the ROS burst and strong hypersensitive response (HR), as well as significant ion leakage. Our data suggest that MiGST_N_4, MiEFh, MiACPS and MiTSPc effectors may be involved in triggering the immune response of the host plant.

A rational design of copper-selenium nanoclusters that cures sepsis by consuming endogenous H2S to trigger photothermal therapy and ROS burst.

The treatment of sepsis caused by bacterial infections is still a huge clinical challenge. As sepsis causes high levels of endogenous H2S in vivo, researchers can design nanomedicines to treat sepsis by in situ sulfurization. Here, we designed and synthesized Cu2O-coated non-metallic core-shell selenium nanoparticles. To cure mice sepsis by ROS burst. Our experimental data displayed that the photothermal effect of Se@Cu9S8 produced by the reaction of Se@Cu2O and endogenous H2S is synergistically antibacterial, and Se@Cu2O has the characteristics of low side effects and high biocompatibility. In summary, our research results verified our design, that copper-selenium nanoclusters may be an efficient strategy to cure sepsis by in situ sulfurization of endogenous H2S, triggering ROS eruptions and photothermal therapy.

The receptor-like cytoplasmic kinase OsRLCK118 regulates plant development and basal immunity in rice (<i>Oryza sativa</i> L.)

Receptor-like cytoplasmic kinases (RLCKs), which belong to a large subgroup of receptor-like kinases in plants, play crucial roles in plant development and immunity. However, their functions and regulatory mechanisms in plants remain unclear. Here, we report functional characterization of OsRLCK118 from the OsRLCK34 subgroup in rice (<italic>Oryza sativa</italic> L.). Expression of <italic>OsRLCK118</italic> could be induced by infections with <italic>Xanthomonas oryzae</italic> pv. <italic>oryzae</italic> (<italic>Xoo</italic>) strains PXO68 and PXO99. Silencing of <italic>OsRLCK118</italic> altered plant height, flag-leaf angle and second-top-leaf angle. Silencing of <italic>OsRLCK118</italic> also resulted in increasing susceptibility to <italic>Xoo</italic> and<italic> Magnaporthe oryzae</italic> (<italic>M. oryzae</italic>) in rice plants. <italic>OsRLCK118</italic> knock-out plants were more sensitive to bacterial blight whereas <italic>OsRLCK118</italic> overexpressor plants exhibited increased disease resistance. Expression levels of pathogenesis-related genes of <italic>OsPAL1</italic>, <italic>OsNH1</italic>, <italic>OsICS1</italic>, <italic>OsPR1a</italic>, <italic>OsPR5</italic> and <italic>OsPR10</italic> were reduced in the <italic>rlck118</italic> mutant compared to wild-type rice (Dongjin) and knock-out of <italic>OsRLCK118</italic> compromised the production of reactive oxygen species. These results suggest that <italic>OsRLCK118</italic> may modulate basal resistance to<italic> Xoo</italic> and <italic>M. oryzae</italic>, possibly through regulation of ROS burst and hormone mediated defense signaling pathway.

Calcium-dependent ABA signaling functions in stomatal immunity by regulating rapid SA responses in guard cells

Stomatal immunity is mediated by ABA, an osmotic stress-responsive phytohormone that closes stomata via calcium-dependent and -independent signaling pathways. However, the functional involvement of ABA signal transducers in stomatal immunity remains poorly understood. Here, we demonstrate that stomatal immunity was compromised in mutants of the ABA signaling core. We also found that it is a subset of calcium-dependent protein kinases (CPK4/5/6), but not the calcium-independent kinase OST1, that relay the stomatal immune signaling. Surface-inoculated bacteria caused an endogenous ABA-dependent induction of local SA responses, whilst expression of the ABA biosynthetic genes and the ABA levels were not affected in leaf epidermis. Furthermore, flg22-elicited ROS burst was attenuated by mutations in CPK4 and CPK5, and pathogen-induced SA production in leaf epidermis was compromised in cpk4, cpk5, and cpk6 mutants. Our results suggest that CPKs function in stomatal immunity through fine-tuning apoplastic ROS levels as well as reinforcing the localized SA signal in guard cells. It is also envisioned that ABA mediates stomatal responses to biotic and abiotic stresses via two distinct but partially overlapping signaling modules.

Physiological, biochemical, and molecular responses of Linum album to digested cell wall of Piriformospora indica.

Plants synthesize a variety of metabolites in response to biotic elicitors. To comprehend how the digested cell wall of Piriformospora indica affects the response of ROS burst, antioxidant enzymes, amino acids profiling, and phenylpropanoid compounds such as lignans, phenolic acids, and flavonoids inLinum albumhairy roots; we accomplished a time-course analysis of metabolite production and enzyme activities in response to CDCW and evaluated the metabolic profiles. The results confirms that CDCW accelerates the H2O2 burst and increases SOD and GPX activity in hairy roots. The HPLC analysis of metabolic profiles shows that the H2O2 burst shifts the amino acids, especially Phe and Tyr, fluxes toward a pool of lignans, phenolic acids, and flavonoids through alterations in the behavior of the necessary enzymes of the phenylpropanoid pathway. CDCW changes PAL, CCR, CAD, and PLR gene expression and transiently induces PTOX and 6MPROX as the main-specific products of PAL and PLR genes expression. The production of phenolic acids (e.g., cinnamic, coumaric, caffeic, and salicylic acid) and flavonoids (e.g., catechin, diosmin, kaempferol, luteolin, naringenin, daidzein, and myricetin) show different behaviors in response to CDCW. In conclusion, our observations show that CDCW elicitation can generate H2O2 molecules in L. album hairy roots and consequently changes physiological, biochemical, and molecular responses such as antioxidant system and the specific active compounds such as lignans. Quantification of metabolic contents in response to CDCW suggests enzyme and non-enzyme defense mechanisms play a crucial role in L. album hairy root adaptation to CDCW. A summary revealed that the correlation between H2O2 generation and L. album hairy root defense system under CDCW. Increase of H2O2 generation led plant to response against oxidative conditions. SOD, and GPX modulated H2O2 content, Phe, and Tyr shifted to the phenylpropanoid compounds as a precursor ofPAL and TAL enzyme, the predominant phenylpropanoid compounds controlled oxidative conditions, and the other amino acids responsible for amino acid synthesis and development stages.

Exogenous Iron Induces NADPH Oxidases-Dependent Ferroptosis in the Conidia of Aspergillus flavus.

Aspergillus flavus is saprophytic soil fungus that contaminates seed crops with the carcinogenic secondary metabolite aflatoxin, posing a significant threat to humans and animals. Ferrous sulfate is a common iron supplement that is used to the treatment of iron-deficiency anemia. Here, we identified an unexpected inhibitory role of ferrous sulfate on A. flavus. With specific fluorescent dyes, we detected several conidial ferroptosis hallmarks in conidia under the treatment of 1 mM Fe2+, including nonapoptosis necrosis, iron-dependent, lipid peroxide accumulation, and ROS burst. However, unlike traditional ferroptosis in mammals, Fe2+ triggered conidial ferroptosis in A. flavus was regulated by NADPH oxidase (NOXs) activation instead of Fenton reaction. Transcriptomic and some other bioinformatics analyses showed that NoxA in A. flavus might be a potential target of Fe2+, and thus led to the occurrence of conidial ferroptosis. Furthermore, noxA deletion mutant was constructed, and both ROS generation and conidial ferroptosis in ΔnoxA was reduced when exposed to Fe2+. Taken together, our study revealed an exogenous Fe2+-triggered conidial ferroptosis pathway mediated by NoxA of A. flavus, which greatly contributes to the development of an alternative strategy to control this pathogen.

Neuroinflammatory Triangle Presenting Novel Pharmacological Targets for Ischemic Brain Injury.

Ischemic stroke is one of the leading causes of morbidity and mortality globally. Hundreds of clinical trials have proven ineffective in bringing forth a definitive and effective treatment for ischemic stroke, except a myopic class of thrombolytic drugs. That, too, has little to do with treating long-term post-stroke disabilities. These studies proposed diverse options to treat stroke, ranging from neurotropic interpolation to venting antioxidant activity, from blocking specific receptors to obstructing functional capacity of ion channels, and more recently the utilization of neuroprotective substances. However, state of the art knowledge suggests that more pragmatic focus in finding effective therapeutic remedy for stroke might be targeting intricate intracellular signaling pathways of the ‘neuroinflammatory triangle’: ROS burst, inflammatory cytokines, and BBB disruption. Experimental evidence reviewed here supports the notion that allowing neuroprotective mechanisms to advance, while limiting neuroinflammatory cascades, will help confine post-stroke damage and disabilities.

Green tea catechins EGCG and ECG enhance the fitness and lifespan of Caenorhabditis elegans by complex I inhibition.

Green tea catechins are associated with a delay in aging. We have designed the current study to investigate the impact and to unveil the target of the most abundant green tea catechins, epigallocatechin gallate (EGCG) and epicatechin gallate (ECG).Experiments were performed in Caenorhabditis elegans to analyze cellular metabolism, ROS homeostasis, stress resistance, physical exercise capacity, health- and lifespan, and the underlying signaling pathways. Besides, we examined the impact of EGCG and ECG in isolated murine mitochondria.A concentration of 2.5 μM EGCG and ECG enhanced health- and lifespan as well as stress resistance in C. elegans. Catechins hampered mitochondrial respiration in C. elegans after 6–12 h and the activity of complex I in isolated rodent mitochondria. The impaired mitochondrial respiration was accompanied by a transient drop in ATP production and a temporary increase in ROS levels in C. elegans. After 24 h, mitochondrial respiration and ATP levels got restored, and ROS levels even dropped below control conditions. The lifespan increases induced by EGCG and ECG were dependent on AAK-2/AMPK and SIR-2.1/SIRT1, as well as on PMK-1/p38 MAPK, SKN-1/NRF2, and DAF-16/FOXO. Long-term effects included significantly diminished fat content and enhanced SOD and CAT activities, required for the positive impact of catechins on lifespan.In summary, complex I inhibition by EGCG and ECG induced a transient drop in cellular ATP levels and a temporary ROS burst, resulting in SKN-1 and DAF-16 activation. Through adaptative responses, catechins reduced fat content, enhanced ROS defense, and improved healthspan in the long term.

GLS1 Filament Formation Facilitates Glutamine Deprivation Induced Cell Death

GLS1 orchestrates glutamine consumption and promotes cell proliferation when glutamine is abundant. Here, we show an unexpected role of GLS1 in facilitating apoptosis when glutamine is deprived. Mechanistically, GLS1 is a sensor for glutamate and glutamate in turn inhibits the conversion of GLS1 from dimer to a kind of micrometer-scale extremely-low-Km filamentous polymer in a dose-dependent manner. Glutamine deprivation decreases glutamate below a threshold, under which glutamate loses the inhibitory effect, allowing self-assembly of GLS1 into the super-activated filament. GLS1 filaments convert the already extremely low level of intracellular glutamine to glutamate to maintain mitochondrial glutamate homeostasis, exacerbating glutamine exhaustion. Glutamine deficiency then blocks the synthesis of asparagine and mitogenome-encoded proteins, leading to impairment of electron transfer, the burst of ROS, and the initiation of TOM40 oxidation-dependent apoptosis. Physiologically, we observed glutamine insufficiency and the GLS1 filaments in solid tumors. Importantly, expression of either K320A or a natural de novo S482C mutation of GLS1, both of which exist in the constitutively super-active filamentous form, dramatically suppresses cancer cell proliferation and tumorigenesis, suggesting that manipulation of GLS1 filament formation might be a potential strategy for cancer therapy.

Extracellular vesicle-based interorgan transport of mitochondria from energetically stressed adipocytes

Adipocytes undergo intense energetic stress in obesity resulting in loss of mitochondrial mass and function. We have found that adipocytes respond to mitochondrial stress by rapidly and robustly releasing small extracellular vesicles (sEVs). These sEVs contain respiration-competent, but oxidatively damaged mitochondrial particles, which enter circulation and are taken up by cardiomyocytes, where they trigger a burst of ROS. The result is compensatory antioxidant signaling in the heart that protects cardiomyocytes from acute oxidative stress, consistent with a preconditioning paradigm. As such, a single injection of sEVs from energetically stressed adipocytes limits cardiac ischemia/reperfusion injury in mice. This study provides the first description of functional mitochondrial transfer between tissues and the first vertebrate example of "inter-organ mitohormesis." Thus, these seemingly toxic adipocyte sEVs may provide a physiological avenue of potent cardio-protection against the inevitable lipotoxic or ischemic stresses elicited by obesity.

Transcriptional Profiling and Functional Analysis of N1/N2 Neutrophils Reveal an Immunomodulatory Effect of S100A9-Blockade on the Pro-Inflammatory N1 Subpopulation.

Neutrophils have been classically viewed as a homogenous population. Recently, neutrophils were phenotypically classified into pro-inflammatory N1 and anti-inflammatory N2 sub-populations, but the functional differences between the two subtypes are not completely understood. We aimed to investigate the phenotypic and functional differences between N1 and N2 neutrophils, and to identify the potential contribution of the S100A9 alarmin in neutrophil polarization. We describe distinct transcriptomic profiles and functional differences between N1 and N2 neutrophils. Compared to N2, the N1 neutrophils exhibited: i) higher levels of ROS and oxidative burst, ii) increased activity of MPO and MMP-9, and iii) enhanced chemotactic response. N1 neutrophils were also characterized by elevated expression of NADPH oxidase subunits, as well as activation of the signaling molecules ERK and the p65 subunit of NF-kB. Moreover, we found that the S100A9 alarmin promotes the chemotactic and enzymatic activity of N1 neutrophils. S100A9 inhibition with a specific small-molecule blocker, reduced CCL2, CCL3 and CCL5 chemokine expression and decreased MPO and MMP-9 activity, by interfering with the NF-kB signaling pathway. Together, these findings reveal that N1 neutrophils are pro-inflammatory effectors of the innate immune response. Pharmacological blockade of S100A9 dampens the function of the pro-inflammatory N1 phenotype, promoting the alarmin as a novel target for therapeutic intervention in inflammatory diseases.

Method for the Production and Purification of Plant Immuno-Active Xylanase from Trichoderma.

Plants lack a circulating adaptive immune system to protect themselves against pathogens. Therefore, they have evolved an innate immune system based upon complicated and efficient defense mechanisms, either constitutive or inducible. Plant defense responses are triggered by elicitors such as microbe-associated molecular patterns (MAMPs). These components are recognized by pattern recognition receptors (PRRs) which include plant cell surface receptors. Upon recognition, PRRs trigger pattern-triggered immunity (PTI). Ethylene Inducing Xylanase (EIX) is a fungal MAMP protein from the plant-growth-promoting fungi (PGPF)–Trichoderma. It elicits plant defense responses in tobacco (Nicotiana tabacum) and tomato (Solanum lycopersicum), making it an excellent tool in the studies of plant immunity. Xylanases such as EIX are hydrolytic enzymes that act on xylan in hemicellulose. There are two types of xylanases: the endo-1, 4-β-xylanases that hydrolyze within the xylan structure, and the β-d-xylosidases that hydrolyze the ends of the xylan chain. Xylanases are mainly synthesized by fungi and bacteria. Filamentous fungi produce xylanases in high amounts and secrete them in liquid cultures, making them an ideal system for xylanase purification. Here, we describe a method for cost- and yield-effective xylanase production from Trichoderma using wheat bran as a growth substrate. Xylanase produced by this method possessed xylanase activity and immunogenic activity, effectively inducing a hypersensitive response, ethylene biosynthesis, and ROS burst.

Smart biomimetic metal organic frameworks based on ROS-ferroptosis-glycolysis regulation for enhanced tumor chemo-immunotherapy

Antitumor immunotherapy is limited by low tumor immunogenicity and immunosuppressive microenvironment (TIME), which could be improved by “ROS-ferroptosis-glycolysis regulation” strategy. Herein, a cancer cell membrane coated metal organic framework (MOF) loading with glucose oxidase (GOx) and doxorubicin (DOX) was constructed (denoted as mFe(SS)/DG). Benefiting from the homotypic targeting of cancer cell membrane, the nanoplatform effectively accumulated in tumors. mFe(SS)/DG based on coordination between Fe3+ and disulfide-bearing ligand scavenged GSH and downregulated glutathione peroxide 4 (GPX4) to trigger ferroptosis. GOx catalyzed glucose to generate abundant H2O2 for enhancing Fenton reaction, resulting in excessive ROS in tumors. The ROS burst simultaneously promoted ferroptosis and inhibited glycolysis. Ferroptosis combined with DOX induced immunogenic cell death (ICD) and released tumor antigens to initiate antitumor immunity. Glycolysis repression remodeled TIME by decreasing lactate to solidify and boost the antitumor immunity. The smart biomimetic nanoplatform integrates tumor metabolism and immunity based on ROS-ferroptosis-glycolysis regulation, providing a potential anti-tumor strategy.

Potential Association of Reactive Oxygen Species With Male Sterility in Peach.

Male sterility is an important agronomic trait for hybrid vigor utilization and hybrid seed production, but its underlying mechanisms remain to be uncovered. Here, we investigated the mechanisms of male sterility in peach using a combined cytology, physiology, and molecular approach. Cytological features of male sterility include deformed microspores and tapetum cells along with absence of pollen grains. Microspores had smaller nucleus at the mononuclear stage and were compressed into belts and subsequently disappeared in the anther cavity, whereas tapetum cells were swollen and vacuolated, with a delayed degradation to flowering time. Male sterile anthers had an ROS burst and lower levels of major antioxidants, which may cause abnormal development of microspores and tapetum, leading to male sterility in peach. In addition, the male sterility appears to be cytoplasmic in peach, which could be due to sequence variation in the mitochondrial genome. Our results are helpful for further investigation of the genetic mechanisms underlying male sterility in peach.

Mitochondria are essential for antibacterial extracellular trap formation mediated by zymosan in hemocytes of Ruditapes philippinarum

The formation of extracellular traps (ETs) is an important innate immune mechanism that serves to combat different invading pathogens. In this study, zymosan significantly induced the formation of ETs in the hemocytes of Ruditapes philippinarum, and this effect was accompanied by translocation of the mitochondria to the cell surface. Zymosan stimulation clearly induced an increase in intracellular ROS and MPO production and an overexpression of ROS-related genes (PI3K, AKT and HIF). In response to the ROS burst, the mitochondrial membrane potential decreased, and the mitochondrial permeability transition pore opened. Conversely, mitochondrial superoxide inhibitor (Mito-TEMPO) significantly inhibited the formation of ETs, suggesting that mitochondrial ROS were necessary for the formation of ETs. In addition, we found that zymosan-induced ETs showed antibacterial activities against gram-negative and gram-positive bacteria, such as Vibrio anguillarum, Vibrio harveyi, Escherichia coli and Micrococcus luteus. Taken together, these findings elucidated a new antibacterial approach for R. philippinarum and highlighted the role of mitochondria in the formation of zymosan-induced ETs.

VDAC1 promotes cardiomyocyteautophagy in anoxia/reoxygenation injury via the PINK1/Parkin pathway.

Ischemia/reperfusion (I/R) is a well-known injury to the myocardium, but the mechanism involved remains elusive. In addition to the well-accepted apoptosis theory, autophagy was recently found to be involved in the process, exerting a dual role as protection in ischemia and detriment in reperfusion. Activation of autophagy is mediated by mitochondrial permeability transition pore (MPTP) opening during reperfusion. In our previous study, we showed that MPTP opening is regulated by VDAC1, a channel protein located in the outer membrane of mitochondria. Thus, upregulation of VDAC1 expression is a possible trigger to cardiomyocyte autophagy via an unclear pathway. Here, we established an anoxia/reoxygenation (A/R) model in vitro to simulate the I/R process in vivo. At the end of A/R treatment, VDAC1, Beclin 1, and LC3-II/I were upregulated, and autophagic vacuoles were increased in cardiomyocytes, which showed a connection of VDAC1 and autophagy development. These variations also led to ROS burst, mitochondrial dysfunction, and aggravated apoptosis. Knockdown of VDAC1 by RNAi could alleviate the above-mentioned cellular damages. Additionally, the expression of PINK1 and Parkin was enhanced after A/R injury. Furthermore, Parkin was recruited to mitochondria from the cytosol, which suggested that the PINK1/Parkin autophagic pathway was activated during A/R. Nevertheless, the PINK1/Parkin pathway was effectively inhibited when VDAC1 was knocked-down. Taken together, the A/R-induced cardiomyocyte injury was mediated by VDAC1 upregulation, which led to cell autophagy via the PINK1/Parkin pathway, and finally aggravated apoptosis.

The Cutinase Bdo_10846 Play an Important Role in the Virulence of Botryosphaeria dothidea and in Inducing the Wart Symptom on Apple Plant.

Botryosphaeria dothidea is a pathogen with worldwide distribution, infecting hundreds of species of economically important woody plants. It infects and causes various symptoms on apple plants, including wart and canker on branches, twigs, and stems. However, the mechanism of warts formation is unclear. In this study, we investigated the mechanism of wart formation by observing the transection ultrastructure of the inoculated cortical tissues at various time points of the infection process and detecting the expression of genes related to the pathogen pathogenicity and plant defense response. Results revealed that wart induced by B. dothidea consisted of proliferous of phelloderm cells, the newly formed secondary phellem, and the suberized phelloderm cells surrounding the invading mycelia. The qRT-PCR analysis revealed the significant upregulation of apple pathogenesis-related and suberification-related genes and a pathogen cutinase gene Bdo_10846. The Bdo_10846 knockout transformants showed reduced cutinase activity and decreased virulence. Transient expression of Bdo_10846 in Nicotiana benthamiana induced ROS burst, callose formation, the resistance of N. benthamiana to Botrytis cinerea, and significant upregulation of the plant pathogenesis-related and suberification-related genes. Additionally, the enzyme activity is essential for the induction. Virus-induced gene silencing demonstrated that the NbBAK1 and NbSOBIR1 expression were required for the Bdo_10846 induced defense response in N. benthamiana. These results revealed the mechanism of wart formation induced by B. dothidea invasion and the important roles of the cutinase Bdo_10846 in pathogen virulence and in inducing plant immunity.

The role of antioxidant mechanism in photosynthesis under heavy metals Cd or Zn exposure in tobacco leaves

ABSTRACT We examined the effects of Cd and Zn exposure on the photosynthetic function and the tolerant mechanisms of ROS metabolism in tobacco leaves. The results showed that the photosynthesis inhibition caused by Cd exposure was due to the limitation of both stomatal and non-stomatal factors, while Zn exposure only showed a significant effect on the Gs of tobacco leaves. Cd increased the generation rate of O2•– and the content of H2O2, but Zn did not lead to the ROS burst. Cd enhanced the POD activity, but inhibited SOD and CAT activities. The activities of SOD and POD significantly increased under Zn exposure. Cd inhibited the activity and expression of APX. The up regulation of GPX, GR and GST expression and the increase of their activities also play a positive role in the adaptation to Cd. Although Zn inhibited the activities of APX and GPX, it had little effect on other enzyme activities and protein expression in AsA-GSH cycle. TPX and TrxR activities, Trx-Prx pathway-related proteins are very sensitive to Cd. However, only PrxQ and 2-Cys Prx BAS1, which are located in chloroplast, and Trx-HFC164 were significantly down-regulated in Trx-Prx pathway under Zn exposure.

Piezo-photocatalytic effect mediating reactive oxygen species burst for cancer catalytic therapy.

A piezo-photocatalytic therapy based on thermally treated natural sphalerite nanosheet (NSH700 NS) heterojunction was applied to efficiently induce intracellular ROS burst and apoptosis of cancer cells. Upon ultrasound and laser irradiation, the formation of a polarized electric field and band bending of NSH700 NSs allow the directional separation of charges both in the bulk and their interface, thereby minimizing the probability of charge recombination. The piezo-photocatalytic effect leads to an efficient catalytic performance, exhibiting high-performance superoxide radical (˙O2-) and hydroxyl radical (˙OH) generation and glutathione (GSH) depletion, which results in a intracellular ROS burst-triggered apoptosis of cancer cells both in vitro and in vivo.

Synthesis of mitochondria-targeted coumarin-3-carboxamide fluorescent derivatives: Inhibiting mitochondrial TrxR2 and cell proliferation on breast cancer cells

Targeting specific mitochondrial alterations to kill cancer cells without affecting their normal counterparts emerges as a feasible strategy. Coumarin derivatives have demonstrated the potential anti-breast cancer activities. By coupling coumarin-3-carboxamide derivatives with mitochondria carrier triphenylphosphonium, mitocoumarins 15a-c were produced and tested as the anti-breast cancer fluorescence agents. Among them, 15b as the amide-based drug potently suppressed the cell growth in MCF-7, MDA-231, SK-BR-3 breast cancer cells with the IC50 values from 3.0 to 4.1 μM, including the lower cytotoxicity to normal MCF-10A cells with the IC50 value around 45.30 ± 2.45 μM. In mechanistic study for 15b in MDA-MB-231 cells, it could localize in mitochondria to elicit ROS burst and collapse Δψm. Besides, it could deplete GSH by an irreversible alkylation process and moderately inhibit mitochondrial thioredoxin reductase TrxR2, thus leading to aggravate cellular oxidative stress. This study reported 15b might be useful for the further development into a mitochondria-targeted anti-triple negative breast cancer drug.