Current methods in quantifying ROS and oxidative damage in Caenorhabditis elegans and other model organism of aging

In Vivo Nanodiamond Quantum Sensing of Free Radicals in Caenorhabditis elegans Models

Free radicals are believed to play a secondary role in the cell death cascade associated with various diseases. In Huntington's disease (HD), the aggregation of polyglutamine (PolyQ) not only contributes to the disease but also elevates free radical levels. However, measuring free radicals is difficult due to their short lifespan and limited diffusion range. Here, a quantum sensing technique (T1 relaxometry) is used that involves fluorescent nanodiamonds (FND). Nitrogen vacancy (NV) centers within these nanodiamonds change their optical properties in response to magnetic noise, which allows detecting the unpaired electron from free radicals. This method is used to monitor the production of free radicals inside Caenorhabditis elegans models of Huntington's disease in vivo and in real-time. To investigate if radical generation occurs near polyglutamine expansions, a strain expressing Q40 yellow fluorescent protein (Q40::YFP, polyglutamine expansion overexpressed in the muscle) is used. By applying T1 relaxometry on FNDs in the body wall muscle, it is found that the production of free radicals significantly increase when PolyQ is expressed there (compared to the FNDs in intestine). The technique demonstrates the submicrometer localization of free radical information in living animals and direct measurement of their level, which may reveal the relation between oxidative stress and Huntington's disease.

Calcium leakage involved in nematotoxic effects of the Conidiobolus obscurus CytCo protein on the pine wood nematode, Bursaphelenchus xylophilus

BACKGROUND

The pine wood nematode Bursaphelenchus xylophilus, a severe invasive species, is responsible for causing widespread pine wilt disease. The CytCo protein, a pore-forming toxin derived from Conidiobolus obscurus, exhibits nematotoxicity towards B. xylophilus.

RESULTS

Our present study reveals the expression variation of a range of gene products in B. xylophilus that respond to the effects of CytCo using the isobaric tags for relative and absolute quantification proteomics technology. Functional enrichment analysis indicates that many differentially expressed proteins are linked to calcium signaling system, proteasome, energy production and conversion, and the determination of adult lifespan. It suggests that the dysregulation of calcium homeostasis, energy metabolism, and apoptosis contribute to the CytCo nematotoxicity. Using the calcium ion (Ca2+)-indicator calcein, we detected changes in Ca2+ levels in B. xylophilus, with a significantly increase in fluorescence in the nematode's intestine and pseudocoelom following CytCo treatments. Meanwhile, the apoptosis and reactive oxygen species (ROS) assays showed an enhancement of fluorescence in B. xylophilus cells, with increased CytCo concentrations.

CONCLUSION

The protein toxin CytCo triggers Ca2+ leakage, disrupts Ca2+ balance in B. xylophilus, and induces apoptosis and ROS outburst, thereby intensifying its nematotoxic effects. This finding facilitates our understanding of the modes of action of nematotoxic proteins, and contributes to the development of innovative nematode control strategies. © 2024 Society of Chemical Industry.

Promising tools into oxidative stress: A review of non-rodent model organisms

Oxidative stress is a crucial concept in redox biology, and significant progress has been made in recent years. Excessive levels of reactive oxygen species (ROS) can lead to oxidative damage, heightening vulnerability to various diseases. By contrast, ROS maintained within a moderate range plays a role in regulating normal physiological metabolism. Choosing suitable animal models in a complex research context is critical for enhancing research efficacy. While rodents are frequently utilized in medical experiments, they pose challenges such as high costs and ethical considerations. Alternatively, non-rodent model organisms like zebrafish, Drosophila, and C. elegans offer promising avenues into oxidative stress research. These organisms boast advantages such as their small size, high reproduction rate, availability for live imaging, and ease of gene manipulation. This review highlights advancements in the detection of oxidative stress using non-rodent models. The oxidative homeostasis regulatory pathway, Kelch-like ECH-associated protein 1-Nuclear factor erythroid 2-related factor 2 (Keap1-Nrf2), is systematically reviewed alongside multiple regulation of Nrf2-centered pathways in different organisms. Ultimately, this review conducts a comprehensive comparative analysis of different model organisms and further explores the combination of novel techniques with non-rodents. This review aims to summarize state-of-the-art findings in oxidative stress research using non-rodents and to delineate future directions.

The effect of common paralytic agents used for fluorescence imaging on redox tone and ATP levels in Caenorhabditis elegans

One aspect of Caenorhabditis elegans that makes it a highly valuable model organism is the ease of use of in vivo genetic reporters, facilitated by its transparent cuticle and highly tractable genetics. Despite the rapid advancement of these technologies, worms must be paralyzed for most imaging applications, and few investigations have characterized the impacts of common chemical anesthetic methods on the parameters measured, in particular biochemical measurements such as cellular energetics and redox tone. Using two dynamic reporters, QUEEN-2m for relative ATP levels and reduction-oxidation sensitive GFP (roGFP) for redox tone, we assess the impact of commonly used chemical paralytics. We report that no chemical anesthetic is entirely effective at doses required for full paralysis without altering redox tone or ATP levels, and that anesthetic use alters the detected outcome of rotenone exposure on relative ATP levels and redox tone. We also assess the use of cold shock, commonly used in combination with physical restraint methods, and find that cold shock does not alter either ATP levels or redox tone. In addition to informing which paralytics are most appropriate for research in these topics, we highlight the need for tailoring the use of anesthetics to different endpoints and experimental questions. Further, we reinforce the need for developing less disruptive paralytic methods for optimal imaging of dynamic in vivo reporters.

Ganoderma lucidum methyl ganoderate E extends lifespan and modulates aging-related indicators in Caenorhabditis elegans

Methyl Ganoderate E (MGE) is a triterpenoid derived from Ganoderma lucidum (Reishi), an edible mushroom, commonly processed into food forms such as soups, drinks, culinary dishes, and supplements. MGE has been shown to inhibit 3T3-L1 murine adipocyte differentiation when combined with other G. lucidum triterpenes. However, the specific effect of MGE on biological processes remains unknown. In this study, we present the first evidence of MGE's anti-aging effect in Caenorhabditis elegans. Through our screening process using the UPRER regulation ability, we evaluated a library of 74 pure compounds isolated from G. lucidum, and MGE exhibited the most promising results. Subsequent experiments demonstrated that MGE extended the lifespan by 26% at 10 μg ml-1 through daf-16, hsf-1, and skn-1-dependent pathways. MGE also enhanced resistance to various molecular stressors, improved healthspan, increased fertility, and reduced the aggregation of alpha-synuclein and amyloid-beta. Transcriptome data revealed that MGE promoted processes associated with proteolysis and neural activity, while not promoting cell death processes. Collectively, our findings suggest that G. lucidum MGE could be considered as a potential anti-aging intervention, adding to the growing list of such interventions.

The role of Caenorhabditis elegans in the discovery of natural products for healthy aging

Covering: 2012 to 2023The human population is aging. Thus, the greatest risk factor for numerous diseases, such as diabetes, cancer and neurodegenerative disorders, is increasing worldwide. Age-related diseases do not typically occur in isolation, but as a result of multi-factorial causes, which in turn require holistic approaches to identify and decipher the mode of action of potential remedies. With the advent of C. elegans as the primary model organism for aging, researchers now have a powerful in vivo tool for identifying and studying agents that effect lifespan and health span. Natural products have been focal research subjects in this respect. This review article covers key developments of the last decade (2012-2023) that have led to the discovery of natural products with healthy aging properties in C. elegans. We (i) discuss the state of knowledge on the effects of natural products on worm aging including methods, assays and involved pathways; (ii) analyze the literature on natural compounds in terms of their molecular properties and the translatability of effects on mammals; (iii) examine the literature on multi-component mixtures with special attention to the studied organisms, extraction methods and efforts regarding the characterization of their chemical composition and their bioactive components. (iv) We further propose to combine small in vivo model organisms such as C. elegans and sophisticated analytical approaches ("wormomics") to guide the way to dissect complex natural products with anti-aging properties.

The effect of common paralytic agents used for fluorescence imaging on redox tone and ATP levels in Caenorhabditis elegans

One aspect of Caenorhabditis elegans that makes it a highly valuable model organism is the ease of use of in vivo genetic reporters, facilitated by its transparent cuticle and highly tractable genetics. Despite the rapid advancement of these technologies, worms must be paralyzed for most imaging applications, and few investigations have characterized the impacts of common chemical anesthetic methods on the parameters measured, in particular biochemical measurements such as cellular energetics and redox tone. Using two dynamic reporters, QUEEN-2m for relative ATP levels and reduction-oxidation sensitive GFP (roGFP) for redox tone, we assess the impact of commonly used chemical paralytics. We report that no chemical anesthetic is entirely effective at doses required for full paralysis without altering redox tone or ATP levels, though 100 mM 2,3-Butadione monoxime appears to be the least problematic. We also assess the use of cold shock, commonly used in combination with physical restraint methods, and find that cold shock does not alter either ATP levels or redox tone. In addition to informing which paralytics are most appropriate for research in these topics, we highlight the need for tailoring the use of anesthetics to different endpoints and experimental questions. Further, we reinforce the need for developing less disruptive paralytic methods for optimal imaging of dynamic in vivo reporters.

Anti-oxidative and anti-aging effects of mannoprotein-rich yeast cell wall enzymatic hydrolysate by modulating gut microbiota and metabolites in Caenorhabditis elegans

In this study, antioxidant and anti-aging studies were carried out by mannoprotein-rich yeast cell wall enzymatic hydrolysate (MYH) obtained by enzymatic hydrolysis of yeast cell wall through the Caenorhabditis elegans (C. elegans) model. It was found that MYH could improve the lifespan and anti-stress ability of C. elegans by increasing the activity of antioxidant enzymes such as T-SOD, GSH-PX and CAT, and reducing the levels of MDA, ROS and apoptosis. At the same time, through the verification expression of corresponding mRNA, it was found that MYH exerted antioxidant and anti-aging activities by up-regulating the translation of MTL-1, DAF-16, SKN-1 and SOD-3 mRNA, and down-regulating the translation of AGE-1 and DAF-2 mRNA. In addition, it was found that MYH could improve the composition and distribution of the gut microbiota of C. elegans, and significantly improve the level of metabolites through the sequencing of gut microbiota and untargeted metabolomic studies. It has contributed to studying the antioxidant and anti-aging activities of microorganisms such as yeast through the level of gut microbiota and metabolites and the development of related functional foods.

Urolithin A Produced by Novel Microbial Fermentation Possesses Anti-aging Effects by Improving Mitophagy and Reducing Reactive Oxygen Species in Caenorhabditis elegans

Urolithin, intestinal microbiota metabolites of ellagitannin-rich foods, exhibit anti-aging activities. However, urolithin A is significantly superior to other types of urolithin with regard to this anti-aging function. This study aimed to screen edible urolithin A-producing strains of bacteria and explore the corresponding anti-aging efficacy of fermented products produced by these strains using Caenorhabditis elegans as a model. Our results showed that the Lactobacillus plantarum strains CCFM1286, CCFM1290, and CCFM1291 converted ellagitannin to produce urolithin A; the corresponding yields of urolithin A from these strains were 15.90 ± 1.46, 24.70 ± 0.82, and 32.01 ± 0.97 μM, respectively. Furthermore, it was found that the pomegranate juice extracts fermented by the CCFM1286, CCFM1290, and CCFM1291 strains of L. plantarum could extend lifespan by 26.04 ± 0.12, 32.05 ± 0.14, and 46.33 ± 0.12%, respectively, by improving mitochondrial function and/or reducing reactive oxygen species levels. These findings highlight the potential application of this fermentation in the subsequent development of anti-aging products.

Dauer larva-derived extracellular vesicles extend the life of Caenorhabditis elegans

There is growing evidence that extracellular vesicles (EVs) play a functional role in tissue repair and anti-aging by transferring the contents of donor cells to recipient cells. We hypothesized that Dauer (C. elegans), known as "ageless" nematodes, can also secrete extracellular vesicles and influence the lifespan of C. elegans. Here, we isolated EVs of dauer larvae (dauer EVs). Dauer EVs were characterized using transmission electron microscopy, nanoparticle tracking analysis (NTA), and Western blot analysis. Wild-type C. elegans were fed in the presence or absence of dauer EVs and tested for a range of phenotypes, including longevity, mobility and reproductive capacity. Results showed that dauer EVs increased the average lifespan of nematodes by 15.74%, improved mobility, slowed age-related pigmentation as well as body length, and reduced the accumulation of reactive oxygen species and lipids, while not impairing nematode reproductive capacity. These findings suggest that dauer EVs can extend the lifespan of C. elegans as well as the healthy lifespan by reducing ROS accumulation, with potential anti-aging capacity.

Effects of Vegetal Extracts and Metabolites against Oxidative Stress and Associated Diseases: Studies in Caenorhabditis elegans

Oxidative stress is a natural physiological process where the levels of oxidants, such as reactive oxygen species (ROS) and nitrogen (RNS), exceed the strategy of antioxidant defenses, culminating in the interruption of redox signaling and control. Oxidative stress is associated with multiple pathologies, including premature aging, neurodegenerative diseases, obesity, diabetes, atherosclerosis, and arthritis. It is not yet clear whether oxidative stress is the cause or consequence of these diseases; however, it has been shown that using compounds with antioxidant properties, particularly compounds of natural origin, could prevent or slow down the progress of different pathologies. Within this context, the Caenorhabditis elegans (C. elegans) model has served to study the effect of different metabolites and natural compounds, which has helped to decipher molecular targets and the effect of these compounds on premature aging and some diseases such as neurodegenerative diseases and dyslipidemia. This article lists the studies carried out on C. elegans in which metabolites and natural extracts have been tested against oxidative stress and the pathologies associated with providing an overview of the discoveries in the redox area made with this nematode.

Imaging of mitochondria/lysosomes in live cells and C. elegans

Two rhodamine-phenothiazine conjugates, RP1 and RP2, were synthesized, and their photophysical properties, subcellular localization, and photocytotoxicity were investigated. We observed robust localization of RP1 in mitochondria and dual localization in mitochondria and lysosomes with RP2 in live cells. Live cell imaging with these probes allowed us to track the dynamics of mitochondria and lysosomes during ROS-induced mitochondrial damage and the subsequent lysosomal digestion of the damaged mitochondria. The fluorophores also demonstrated preferential accumulation in cancer cells compared to normal cells and had strong photo-cytotoxicity. However, no cytotoxicity was observed in the dark. The mitochondrial staining and light-induced ROS production were not limited to mammalian cell lines, but were also observed in the animal model C. elegans. The study demonstrated the potential applications of these probes in visualizing the mitochondria-lysosome cross-talk after ROS production and for photodynamic therapy.

Identification of a Hydroxygallic Acid Derivative, Zingibroside R1 and a Sterol Lipid as Potential Active Ingredients of Cuscuta chinensis Extract That Has Neuroprotective and Antioxidant Effects in Aged Caenorhabditis elegans

We examined the effects of the extracts from two traditional Chinese medicine plants, Cuscuta chinensis and Eucommia ulmoides, on the healthspan of the model organism Caenorhabditis elegans. C. chinensis increased the short-term memory and the mechanosensory response of aged C. elegans. Furthermore, both extracts improved the resistance towards oxidative stress, and decreased the intracellular level of reactive oxygen species. Chemical analyses of the extracts revealed the presence of several bioactive compounds such as chlorogenic acid, cinnamic acid, and quercetin. A fraction from the C. chinensis extract enriched in zingibroside R1 improved the lifespan, the survival after heat stress, and the locomotion in a manner similar to the full C. chinensis extract. Thus, zingibroside R1 could be (partly) responsible for the observed health benefits of C. chinensis. Furthermore, a hydroxygallic acid derivative and the sterol lipid 4-alpha-formyl-stigmasta-7,24(241)-dien-3-beta-ol are abundantly present in the C. chinensis extract and its most bioactive fraction, but hardly in E. ulmoides, making them good candidates to explain the overall healthspan benefits of C. chinensis compared to the specific positive effects on stress resistance by E. ulmoides. Our findings highlight the overall anti-aging effects of C. chinensis in C. elegans and provide first hints about the components responsible for these effects.

Structural features and antioxidant activities of polysaccharides from different parts of Codonopsis pilosula var. modesta (Nannf.) L. T. Shen

In this study, three acidic polysaccharides from different plant parts of Codonopsis pilosula var. Modesta (Nannf.) L. T. Shen were obtained by ion exchange chromatography and gel filtration chromatography, and the yields of these three polysaccharides were different. According to the preliminary experimental results, the antioxidant activities of the polysaccharides from rhizomes and fibrous roots (CLFP-1) were poor, and was thus not studied further. Due to this the structural features of polysaccharides from roots (CLRP-1) and aerial parts (CLSP-1) were the object for this study and were structurally characterized, and their antioxidant activities were evaluated. As revealed by the results, the molecular weight of CLRP-1and CLSP-1 were 15.9 kDa and 26.4 kDa, respectively. The monosaccharide composition of CLRP-1 was Ara, Rha, Fuc, Xyl, Man, Gal, GlcA, GalA in a ratio of 3.8: 8.4: 1.0: 0.8: 2.4: 7.4: 7.5: 2.0: 66.7, and Ara, Rha, Gal, GalA in a ratio of 5.8: 8.9: 8.0: 77.0 in for CLSP-1. The results of structural elucidation indicated that both CLRP-1 and CLSP-1 were pectic polysaccharides, mainly composed of 1, 4-linked galacturonic acid with long homogalacturonan regions. Arabinogalactan type I and arabinogalactan type II were presented as side chains. The antioxidant assay in IPEC-J2 cells showed that both CLRP-1 and CLSP-1 promoted cell viability and antioxidant activity, which significantly increase the level of total antioxidant capacity and the activity of superoxide dismutase, catalase, and decrease the content of malondialdehyde. Moreover, CLRP-1 and CLSP-1 also showed powerful antioxidant abilities in Caenorhabditis elegans and might regulate the nuclear localization of DAF-16 transcription factor, induced antioxidant enzymes activities, and further reduced reactive oxygen species and malondialdehyde contents to increase the antioxidant ability of Caenorhabditis elegans. Thus, these finding suggest that CLRP-1 and CLSP-1 could be used as potential antioxidants.

Copper and Chromium toxicity is mediated by oxidative stress in Caenorhabditis elegans: The use of nanoparticles as an immobilization strategy

Environmental contamination by heavy metals (HMs) has impelled searching for stabilization strategies, where the use of zero-valent iron nanoparticles (nZVI) is considered a promising option. We have evaluated the combined effect of Cu(II)-Cr(VI) on two Caenorhabditis elegans strains (N2 and RB1072 sod-2 mutant) in aqueous solutions and in a standard soil, prior and after treatment with nZVI (5% w/w). The results showed that HMs aqueous solutions had an intense toxic effect on both strains. Production of reactive oxygen species and enhanced expression of the heat shock protein Hsp-16.2 was observed, indicating increased HM-mediated oxidative stress. Toxic effects of HM-polluted soil on worms were higher for sod-2 mutant than for N2 strain. However, nZVI treatment significantly diminished all these effects. Our findings highlighted C. elegans as a sensitive indicator for HMs pollution and its usefulness to assess the efficiency of the nanoremediation strategy to decrease the toxicity of Cu(II)-Cr(VI) polluted environments.

Oxidation and Antioxidation of Natural Products in the Model Organism Caenorhabditiselegans

Natural products are small molecules naturally produced by multiple sources such as plants, animals, fungi, bacteria and archaea. They exert both beneficial and detrimental effects by modulating biological targets and pathways involved in oxidative stress and antioxidant response. Natural products’ oxidative or antioxidative properties are usually investigated in preclinical experimental models, including virtual computing simulations, cell and tissue cultures, rodent and nonhuman primate animal models, and human studies. Due to the renewal of the concept of experimental animals, especially the popularization of alternative 3R methods for reduction, replacement and refinement, many assessment experiments have been carried out in new alternative models. The model organism Caenorhabditis elegans has been used for medical research since Sydney Brenner revealed its genetics in 1974 and has been introduced into pharmacology and toxicology in the past two decades. The data from C. elegans have been satisfactorily correlated with traditional experimental models. In this review, we summarize the advantages of C. elegans in assessing oxidative and antioxidative properties of natural products and introduce methods to construct an oxidative damage model in C. elegans. The biomarkers and signaling pathways involved in the oxidative stress of C. elegans are summarized, as well as the oxidation and antioxidation in target organs of the muscle, nervous, digestive and reproductive systems. This review provides an overview of the oxidative and antioxidative properties of natural products based on the model organism C. elegans.

Current Understanding of Modes of Action of Multicomponent Bioactive Phytochemicals: Potential for Nutraceuticals and Antimicrobials

Plants produce a diversity of plant secondary metabolites (PSMs), which function as defense chemicals against herbivores and microorganisms but also as signal compounds. An individual plant produces and accumulates mixtures of PSMs with different structural features using different biosynthetic pathways. Almost all PSMs exert one or several biological activities that can be useful for nutrition and health. This review discusses the modes of action of PSMs alone and in combinations. In a mixture, most individual PSMs can modulate different molecular targets; they are thus multitarget drugs. In an extract with many multitarget chemicals, additive and synergistic effects occur. Experiments with the model system Caenorhabditis elegans show that polyphenols and carotenoids can function as powerful antioxidative and longevity-promoting PSMs. PSMs of food plants and spices often exhibit antioxidant, anti-inflammatory, and antimicrobial properties, which can be beneficial for health and the prevention of diseases. Some extracts from food plants and spices with bioactive PSMs have potential for nutraceuticals and antimicrobials.

Mechanism of Longevity Extension of Caenorhabditis elegans Induced by Schizophyllum commune Fermented Supernatant With Added Radix Puerariae

Schizophyllum commune (S. commune) fermented supernatant with added Radix Puerariae (SC-RP) showed significant antioxidant activity in our previous work. However, the possible lifespan and healthspan extending the capacity of Caenorhabditis elegans (C. elegans) and the underlying mechanism were not illuminated. In this study, the effect of SC-RP on extending the lifespan and improving stress resistance of C. elegans were examined. Additionally, the underlying lifespan extending molecular mechanisms of SC-RP were explored. Treated with SC-RP at 10 μg/mL, the lifespan of C. elegans increased by 24.89% (P < 0.01). Also, SC-RP prolonged the healthspan of the nematode, including reducing lipofuscin levels, improving mobility and enhancing resistance to oxidative stress and heat shock. Moreover, superoxide dismutase and catalase activities were increased for SC-RP treated C. elegans. Meantime the intracellular levels of thiobarbituric acid reactive substances (TBARS) and reactive oxygen species (ROS) were attenuated. Express levels of eight genes including daf-2, daf-16, sod-3, skn-1, gst-4, clk-1, age-1 and mev-1 were analyzed by RT-PCR method for possible C. elegan anti-aging mechanisms of SC-RP. Expression levels of key genes daf-2, gst-4 and sod-3 were up-regulated, while that of daf-16, skn-1, and clk-1 were down-regulated. The results suggest that SC-RP could extend the lifespan and healthspan of C. elegans significantly, and the IIS pathway, SKN-1/Nrf2 pathway and mitochondrial metabolism pathway were primarily considered associated. Thus, SC-RP is a potential component to improve aging and aging-related symptoms as new functional materials.

Cellular senescence, rejuvenation and potential immortality

Ageing, death, and potential immortality lie at the heart of biology, but two seemingly incompatible paradigms coexist in different research communities and have done since the nineteenth century. The universal senescence paradigm sees senescence as inevitable in all cells. Damage accumulates. The potential immortality paradigm sees some cells as potentially immortal, especially unicellular organisms, germ cells and cancerous cells. Recent research with animal cells, yeasts and bacteria show that damaged cell constituents do in fact build up, but can be diluted by growth and cell division, especially by asymmetric cell division. By contrast, mammalian embryonic stem cells and many cancerous and 'immortalized' cell lines divide symmetrically, and yet replicate indefinitely. How do they acquire their potential immortality? I suggest they are rejuvenated by excreting damaged cell constituents in extracellular vesicles. If so, our understanding of cellular senescence, rejuvenation and potential immortality could be brought together in a new synthesis, which I call the cellular rejuvenation hypothesis: damaged cell constituents build up in all cells, but cells can be rejuvenated either by growth and cell division or, in 'immortal' cell lines, by excreting damaged cell constituents. In electronic supplementary material, appendix, I outline nine ways in which this hypothesis could be tested.

Kanglexin delays heart aging by promoting mitophagy

Heart aging is characterized by structural and diastolic dysfunction of the heart. However, there is still no effective drug to prevent and treat the abnormal changes in cardiac function caused by aging. Here, we present the preventive effects of emodin and its derivative Kanglexin (KLX) against heart aging. We found that the diastolic dysfunction and cardiac remodeling in mice with D-galactose (D-gal)-induced aging were markedly mitigated by KLX and emodin. In addition, the senescence of neonatal mouse cardiomyocytes induced by D-gal was also reversed by KLX and emodin treatment. However, KLX exhibited better anti-heart aging effects than emodin at the same dose. Dysregulated mitophagy was observed in aging hearts and in senescent neonatal mouse cardiomyocytes, and KLX produced a greater increase in mitophagy than emodin. The mitophagy-promoting effects of KLX and emodin were ascribed to their abilities to enhance the protein stability of Parkin, a key modulator in mitophagy, with different potencies. Molecular docking and SPR analysis demonstrated that KLX has a higher affinity for the ubiquitin-like (UBL) domain of Parkin than emodin. The UBL domain might contribute to the stabilizing effects of KLX on Parkin. In conclusion, this study identifies KLX and emodin as effective anti-heart aging drugs that activate Parkin-mediated mitophagy and outlines their putative therapeutic importance.

Apigenin Alleviates Intervertebral Disc Degeneration via Restoring Autophagy Flux in Nucleus Pulposus Cells

Oxidative stress–induced apoptosis and senescence of nucleus pulposus (NP) cells play a crucial role in the progression of intervertebral disc degeneration (IVDD). Accumulation of studies has shown that activated autophagy and enhanced autophagic flux can alleviate IVDD. In this study, we explored the effects of apigenin on IVDD in vitro and in vivo. Apigenin was found to inhibit tert-butyl hydroperoxide (TBHP)–induced apoptosis, senescence, and ECM degradation in NP cells. In addition, apigenin treatment can restore the autophagic flux blockage caused by TBHP. Mechanistically, we found that TBHP may induce autophagosome and lysosome fusion interruption and lysosomal dysfunction, while apigenin alleviates these phenomena by promoting the nuclear translocation of TFEB via the AMPK/mTOR signaling pathway. Furthermore, apigenin also exerts a protective effect against the progression of IVDD in the puncture-induced rat model. Taken together, these findings indicate that apigenin protects NP cells against TBHP-induced apoptosis, senescence, and ECM degradation via restoration of autophagic flux in vitro, and it also ameliorates IVDD progression in rats in vivo, demonstrating its potential for serving as an effective therapeutic agent for IVDD.

Sonneradon A Extends Lifespan of Caenorhabditis elegans by Modulating Mitochondrial and IIS Signaling Pathways

Aging is related to the lowered overall functioning and increased risk for various age-related diseases in humans. Sonneradon A (SDA), a new compound first extracted from the edible fruits of mangrove Sonneratia apetala, showed remarkable antiaging activity. However, the role of SDA in antiaging remains unclear. In this article, we studied the function of SDA in antiaging by using the animal model Caenorhabditis elegans. Results showed that SDA inhibited production of reactive oxygen species (ROS) by 53%, and reduced the accumulation of aging markers such as lipids and lipofuscins. Moreover, SDA also enhanced the innate immune response to Pseudomonas aeruginosa infection. Genetic analysis of a series of mutants showed that SDA extended the lifespan of the mutants of eat-2 and glp-1. Together, this effect may be related to the enhanced resistance to oxidative stress via mitochondrial and insulin/insulin-like growth factor-1 signaling (IIS) pathways. The results of this study provided new evidence for an antiaging effect of SDA in C. elegans, as well as insights into the implication of antiaging activity of SDA in higher organisms.

OUP accepted manuscript

Although arsenic (As) is a persistent contaminant in the environment, few studies have assessed its effects over generations, as it requires an animal model with a short lifespan and rapid development, such as the nematode Caenorhabditis elegans. Furthermore, few studies have evaluated the effects of As metabolites such as dimethylarsinic acid (DMA^V), and several authors have considered DMA as a moderately toxic intermediate of As, although recent studies have shown that this chemical form can be more toxic than inorganic arsenic (iAs) even at low concentrations. In the present study, we compared the toxic effects of arsenate (As^V) and DMA^V in C. elegans over 5 subsequent generations. We evaluated biochemical parameters such as reactive oxygen species (ROS) concentration, the activity of antioxidant defense system (ADS) enzymes such as catalase (CAT) and glutathione-S-transferase (GST), and nonenzymatic components of ADS such as reduced glutathione (GSH) and protein-sulfhydryl groups (P-SH). Exposure to 50 μg L^-1 of As^V led to an increase in ROS generation and GSH levels together with a decrease in GST activity, while exposure to DMA^V led to an increase in ROS levels, with an increase in lipid peroxidation, CAT activity, and a decrease in GSH levels. In addition, both treatments reduced animal growth from the third generation onward and caused disturbances in their reproduction throughout all 5 generations. This study shows that the accumulated effects of DMA need to be considered; it highlights the importance of this type of multigenerational approach for evaluating the effects of organic contaminants considered low or nontoxic.

Drp-1-Dependent Mitochondrial Fragmentation Contributes to Cobalt Chloride-Induced Toxicity in Caenorhabditis elegans

Excess cobalt may lead to metallosis, characterized by sensorineural hearing loss, visual, and cognitive impairment, and peripheral neuropathy. In the present study, we sought to address the molecular mechanisms of cobalt-induced neurotoxicity, using Caenorhabditis elegans as an experimental model. Exposure to cobalt chloride for 2 h significantly decreased the survival rate and lifespan in nematodes. Cobalt chloride exposure led to increased oxidative stress and upregulation of glutathione S-transferase 4. Consistently, its upstream regulator skn-1, a mammalian homolog of the nuclear factor erythroid 2-related factor 2, was activated. Among the mRNAs examined by quantitative real-time polymerase chain reactions, apoptotic activator egl-1, proapoptotic gene ced-9, autophagic (bec-1 and lgg-1), and mitochondrial fission regulator drp-1 were significantly upregulated upon cobalt exposure, concomitant with mitochondrial fragmentation, as determined by confocal microscopy. Moreover, drp-1 inhibition suppressed the cobalt chloride-induced reactive oxygen species generation, growth defects, and reduced mitochondrial fragmentation. Our novel findings suggest that the acute toxicity of cobalt is mediated by mitochondrial fragmentation and drp-1 upregulation.

Caenorhabditis elegans as a model for studies on quinolinic acid-induced NMDAR-dependent glutamatergic disorders

Quinolinic acid (QUIN) is an agonist of the neurotransmitter glutamate (Glu) capable of binding to N-methyl-D-aspartate receptors (NMDAR) increasing glutamatergic signaling. QUIN is known for being an endogenous neurotoxin, able to induce neurodegeneration. In Caenorhabditis elegans, the mechanism by which QUIN induces behavioral and metabolic toxicity has not been fully elucidated. The effects of QUIN on behavioral and metabolic parameters in nmr-1 and nmr-2 NMDA receptors in transgenic and wild-type (WT) worms were performed to decipher the pathway by which QUIN exerts its toxicity. QUIN increased locomotion parameters such as wavelength and movement amplitude medium, as well as speed and displacement, without modifying the number of body bends in an NMDAR-dependent-manner. QUIN increased the response time to the chemical stimulant 1-octanol, which is modulated by glutamatergic neurotransmission in the ASH neuron. Brood size increased after exposure to QUIN, dependent upon nmr-2/NMDA-receptor, with no change in lifespan. Oxygen consumption, mitochondrial membrane potential, and the flow of coupled and unbound electrons to ATP production were reduced by QUIN in wild-type animals, but did not alter citrate synthase activity, altering the functionality but the mitochondrial viability. Notably, QUIN modified fine locomotor and chemosensory behavioral parameters, as well as metabolic parameters, analogous to previously reported effects in mammals. Our results indicate that QUIN can be used as a neurotoxin to elicit glutamatergic dysfunction in C. elegans in a way analogous to other animal models.

Red Cabbage Rather Than Green Cabbage Increases Stress Resistance and Extends the Lifespan of Caenorhabditis elegans

Many studies have demonstrated that cabbages possess various biological activities, and our previous studies confirmed that cyanidin-3-diglucoside-5-glucoside (CY3D5G), the major core of red cabbage anthocyanins, exhibited in vitro antioxidant activity. This study further investigated the protective effects of CY3D5G derivative from red cabbage juice (RCJ) on oxidative stress and lifespan in cells and Caenorhabditis elegans, green cabbage juice (GCJ) was used as control. RCJ rather than GCJ significantly improved cell viability and decreased lactate dehydrogenase release in H₂O₂-induced caco-2 cells. RCJ significantly increased survival during oxidative and heat stress and mean lifespan in C. elegans by 171.63% and 31.64%, and 28.16%, respectively, while GCJ treatment showed no significant effects (p < 0.05). These results might be attributed to significantly (p < 0.05) higher contents of total phenolics, ascorbic acid, glucosinolates, and anthocyanins in RCJ compared to those in GCJ. Additionally, both of them decreased autofluorescence and reproductive capacity, increased body length, but did not alter the intracellular ROS level. Prolonged lifespan by RCJ might require heat-shock transcription factor pathway, sirtuin signaling, and calmodulin kinase II pathway, independent of insulin/insulin-like growth factor-1 signaling pathway. RCJ showed promising antioxidant properties in caco-2 cells and C. elegans, which provided more information on the health benefits of cabbage.

Downregulation of glob1 suppresses pathogenesis of human neuronal tauopathies in Drosophila by regulating tau phosphorylation and ROS generation

Human tauopathies represent a group of neurodegenerative disorders, characterized by abnormal hyperphosphorylation and aggregation of tau protein, which ultimately cause neurodegeneration. The aberrant tau hyperphosphorylation is mostly attributed to the kinases/phosphatases imbalance, which is majorly contributed by the generation of reactive oxygen species (ROS). Globin(s) represent a well-conserved group of proteins which are involved in O₂ management, regulation of cellular ROS in different cell types. Similarly, Drosophila globin1 (a homologue of human globin) with its known roles in oxygen management and development of nervous system exhibits striking similarities with the mammalian neuroglobin. Several recent evidences support the hypothesis that neuroglobins are associated with Alzheimer's disease pathogenesis. We herein noted that targeted expression of human-tau induces the cellular level of Glob1 protein in Drosophila tauopathy models. Subsequently, RNAi mediated restored level of Glob1 restricts the pathogenic effect of human-tau by minimizing its hyperphosphorylation via GSK-3β/p-Akt and p-JNK pathways. In addition, it also activates the Nrf2-keap1-ARE cascade to stabilize the tau-mediated increased level of ROS. These two parallel cellular events provide a significant rescue against human tau-mediated neurotoxicity in the fly models. For the first time we report a direct involvement of an oxygen sensing globin gene in tau etiology. In view of the fact that human genome encodes for the multiple Globin proteins including a nervous system specific neuroglobin; and therefore, our findings may pave the way to investigate if the conserved oxygen sensing globin gene(s) can be exploited in devising novel therapeutic strategies against tauopathies.

Health and longevity studies in C. elegans: the "healthy worm database" reveals strengths, weaknesses and gaps of test compound-based studies

Several biogerontology databases exist that focus on genetic or gene expression data linked to health as well as survival, subsequent to compound treatments or genetic manipulations in animal models. However, none of these has yet collected experimental results of compound-related health changes. Since quality of life is often regarded as more valuable than length of life, we aim to fill this gap with the “Healthy Worm Database” (http://healthy-worm-database.eu). Literature describing health-related compound studies in the aging model Caenorhabditis elegans was screened, and data for 440 compounds collected. The database considers 189 publications describing 89 different phenotypes measured in 2995 different conditions. Besides enabling a targeted search for promising compounds for further investigations, this database also offers insights into the research field of studies on healthy aging based on a frequently used model organism. Some weaknesses of C. elegans-based aging studies, like underrepresented phenotypes, especially concerning cognitive functions, as well as the convenience-based use of young worms as the starting point for compound treatment or phenotype measurement are discussed. In conclusion, the database provides an anchor for the search for compounds affecting health, with a link to public databases, and it further highlights some potential shortcomings in current aging research.

Comprehensive Review of Methodology to Detect Reactive Oxygen Species (ROS) in Mammalian Species and Establish Its Relationship with Antioxidants and Cancer

Evidence suggests that reactive oxygen species (ROS) mediate tissue homeostasis, cellular signaling, differentiation, and survival. ROS and antioxidants exert both beneficial and harmful effects on cancer. ROS at different concentrations exhibit different functions. This creates necessity to understand the relation between ROS, antioxidants, and cancer, and methods for detection of ROS. This review highlights various sources and types of ROS, their tumorigenic and tumor prevention effects; types of antioxidants, their tumorigenic and tumor prevention effects; and abnormal ROS detoxification in cancer; and methods to measure ROS. We conclude that improving genetic screening methods and bringing higher clarity in determination of enzymatic pathways and scale-up in cancer models profiling, using omics technology, would support in-depth understanding of antioxidant pathways and ROS complexities. Although numerous methods for ROS detection are developing very rapidly, yet further modifications are required to minimize the limitations associated with currently available methods.

Facilitating Drug Discovery in Human Disease Models Using Insects

Drugs are developed through basic studies and clinical trials. In basic studies, researchers seek drug candidates using in vitro evaluation systems and subsequently examine their effectiveness in animal experiments as in vivo evaluations. Drug candidates identified in basic studies are tested to determine whether they are effective against human diseases in clinical trials. However, most drug candidates identified in in vitro evaluation systems do not show therapeutic effects in animal experiments due to pharmacokinetics and toxicity problems in the in vivo evaluations. This review outlines drug discovery using insect disease models that allow us to perform in vivo screening. Since insects have various advantages as experimental animals such as low cost for rearing and few ethical concerns, researchers can perform large-scale in vivo screening to find drug candidates. Silkworms are insects frequently used for studies of drug efficacy, pharmacokinetics, and toxicity. Based on silkworm research, I describe the benefits of using insect disease models for drug discovery. The use of insect disease models for in vivo screening is expected to facilitate drug discovery.

Comprehensive phenotyping and multi-omic profiling in the toxicity assessment of nanopolystyrene with different surface properties

There is a growing concern regarding the toxic effects of terrestrial nanoplastic contaminants. However, an all-encompassing phenotyping- and omics-based strategy for the toxicity assessment of nanoplastics with different surface properties on soil living organisms remains to be established. Herein, we devised a comprehensive phenotyping and multi-omic profiling method to examine the molecular disturbance of nanopolystyrene (PS)-exposed Caenorhabditis elegans. The exposure time was 24 h with either 1 μg/mL or 10 μg/mL of PS. We found that PS considerably affected the reproduction and locomotion, as well as increased the oxidative stress of worms regardless of their surface properties. Nevertheless, each type of PS affected the metabolome and lipidome of the nematodes differently. Uncharged PS (PS-N) triggered significant metabolic disturbances, whereas the metabolic influences from PS-NH₂ and PS-COOH were subtle. The dysregulated transcriptome profiles of PS-N were strongly associated with the metabolic pathways. Besides, the altered expression of several genes associated with autophagy and longevity was observed. Collectively, we demonstrated that comprehensive phenotyping and omics-based profiling establish a practical framework that allows us to gain deeper insights into the maladaptive consequences of PS in nematodes. It can be utilized for the evaluation of other environmental contaminants in the terrestrial ecosystem.

Influence of a combination of triptolide and ferulic acid on the activities of CYP450 enzymes and oxidative stress in HaCaT cells

Topical administration of triptolide (TP) is effective in the treatment of rheumatoid arthritis (RA), but it can also induce skin irritation. Previous studies have used data mining strategies to analyze the application of Tripterygium wilfordii in the treatment of RA and have shown that TP and ferulic acid (FA) can be used in combination due to their component compatibility. The aims of the present study were to investigate the mechanisms underlying the effects of TP treatment and to identify its effects on metabolism and oxidative damage in the skin. MTT assay results suggested that the HaCaT cell survival rate was significantly increased when the compatibility ratio of TP to FA was 1:100. Moreover, the combination of TP with FA (TP + FA) did not significantly affect the activities of the cytochrome P40 (CYP) enzymes CYP family 1 subfamily A member 2 (CYP1A2), CYP2E1 and CYP3A4, when used as a 'cocktail'. It was found that TP + FA significantly decreased the production levels of reactive oxygen species (ROS), superoxide dismutase and malondialdehyde in HaCaT cells, while significantly increasing levels of glutathione and catalase. In addition, TP + FA significantly increased nuclear factor erythroid 2-related factor 2 protein expression, compared with TP alone. Thus, the present results indicated that the underlying mechanism of TP + FA efficacy may be related to decreased ROS production level in HaCaT cells, increased production levels of key antioxidant factors and increased antioxidant activity of the epidermis, all of which were correlated with a protective effect against oxidative damage.

Piquiá Shells (Caryocar villosum): A Fruit by-Product with Antioxidant and Antiaging Properties in Caenorhabditis elegans

In a context of rising demand for sustainable antiaging interventions, fruit processing by-products are a promising source of bioactive compounds for the production of antiaging dietary supplements. Piquiá (Caryocar villosum) is a native Amazonian fruit consisting of 65% nonedible shells. In the present study, the phytochemical profile of a hydroalcoholic extract of piquiá shells (CV) was characterized by LC-MS/MS analysis. Its antioxidant and antiaging activities were investigated using the nematode Caenorhabditis elegans as an in vivo model. CV is mainly composed by hydrolysable tannins and triterpenoid saponins. The extract enhanced stress resistance of wild-type and mutant worms by reducing the intracellular levels of reactive oxygen species (ROS) and by increasing their survival against a lethal dose of the prooxidant juglone. These effects involved the upregulation of sod-3 and downregulation of gst-4 and hsp-16.2, studied through the GFP fluorescent reporter intensity and at the transcriptional level by qRT-PCR analysis. CV extended the lifespan of wild-type worms in a DAF-16/FoxO- and SKN-1/Nrf-dependent manner. Taken together, our findings indicate piquiá shells as potential candidates for nutraceutical applications. Further studies are needed to validate the relevance of our findings to antiaging interventions in humans.

An Understudied Dimension: Why Age Needs to Be Considered When Studying Epigenetic-Environment Interactions

We live in a complex chemical environment where there are an estimated 350 000 chemical compounds or mixtures commercially produced. A strong body of literature shows that there are time points during early development when an organism’s epigenome is particularly sensitive to chemicals in its environment. What is less understood is how gene-environment and epigenetic-environment interactions change with age. This question is bidirectional: (1) how do chemicals in the environment affect the aging process and (2) how does aging affect an organism’s response to its chemical environment? The study of gene-environment interactions with age is especially important because, in many parts of the world, older individuals are a large and rapidly growing proportion of the population and because aging is a process universal to most of the animal kingdom. Epigenetics has emerged as a crucial framework for studying aging as epigenetic pathways, often triggered by environmental stimuli, have been shown to be essential regulators of the aging process. In this perspective article, we delineate the connection between aging, epigenetics, and environmental exposures. We discuss why it is essential to consider age when researching how an organism interacts with its environment. We describe recent advances in understanding how the chemical environment affects aging and the gap in research on how age affects an organism’s response to the environment. Finally, we highlight how model organisms and network approaches can help fill this crucial gap. Taken together, systemic changes that occur in the epigenome with age indicate that adult organisms cannot be treated as a homogeneous population and that there are discrete mechanisms modulating the aging epigenome that we do not yet understand.

5'-Hydroxy-6, 7, 8, 3', 4'-pentamethoxyflavone extends longevity mediated by DR-induced autophagy and oxidative stress resistance in C. elegans

5'-Hydroxy-6, 7, 8, 3', 4'-pentamethoxyflavone (5-HPF), a polymethoxyflavone compound found in dikamali gum, has been shown to exert a range of beneficial effects on health. We have previously reported that 5-HPF improves the cholinergic dysfunction and also possesses antioxidant properties in Caenorhabditis elegans. In this study, we have identified the effect of 5-HPF on the worm lifespan and its underlying molecular mechanisms. Out of the five tested pharmacological doses of 5-HPF, viz. 6.25, 12.5, 25, 50, and 100 μM, the 50 μM dose maximally extended the mean life of C. elegans by 28%. The present study revealed that 5-HPF supplementation leads to dietary restriction (DR)-like effects in the worms without altering bacterial metabolism. The analysis of mutant animals fed with 5-HPF suggested that the extended lifespan of C. elegans depends upon multiple DR-related signaling pathways, with NRF2 and FOXA being critical factors. Further investigation into the mechanistic aspects indicated that 5-HPF utilizes autophagy pathway induced by DR through the upregulation of autophagy genes bec-1 and lgg-1, evident from the increase in autophagic puncta in the seam cells of lgg-1::gfp tagged worms. This study identifies the longevity-promoting activity of 5-HPF in C. elegans regulated by oxidative stress-resistance genes and DR-induced autophagy pathway.

Caernohabditis elegans as a Model Organism to Evaluate the Antioxidant Effects of Phytochemicals

The nematode Caernohabditis elegans was introduced as a model organism in biological research by Sydney Brenner in the 1970s. Since then, it has been increasingly used for investigating processes such as ageing, oxidative stress, neurodegeneration, or inflammation, for which there is a high degree of homology between C. elegans and human pathways, so that the worm offers promising possibilities to study mechanisms of action and effects of phytochemicals of foods and plants. In this paper, the genes and pathways regulating oxidative stress in C. elegans are discussed, as well as the methodological approaches used for their evaluation in the worm. In particular, the following aspects are reviewed: the use of stress assays, determination of chemical and biochemical markers (e.g., ROS, carbonylated proteins, lipid peroxides or altered DNA), influence on gene expression and the employment of mutant worm strains, either carrying loss-of-function mutations or fluorescent reporters, such as the GFP.

The Implication of Oxidative Stress and AMPK-Nrf2 Antioxidative Signaling in Pneumonia Pathogenesis

It is widely recognized that chemical, physical, and biological factors can singly or synergistically evoke the excessive production of oxidative stress in pulmonary tissue that followed by pulmonary lesions and pneumonia. In addition, metabolic and endocrine disorder-induced diseases such as diabetes and obesity often expressed higher susceptibility to pulmonary infections, and presented severe symptoms which increasing the mortality rate. Therefore, the connection between the lesion of the lungs and the metabolic/endocrine disorders is an interesting and essential issue to be addressed. Studies have noticed a similar pathological feature in both infectious pneumonia and metabolic disease-intercurrent pulmonary lesions, that is, from the view of molecular pathology, the accumulation of excessive reactive oxygen species (ROS) in pulmonary tissue accompanying with activated pro-inflammatory signals. Meanwhile, Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) and nuclear factor erythroid-2-related factor 2 (Nrf2) signaling plays important role in metabolic/endocrine homeostasis and infection response, and it's closely associated with the anti-oxidative capacity of the body. For this reason, this review will start from the summary upon the implication of ROS accumulation, and to discuss how AMPK-Nrf2 signaling contributes to maintaining the metabolic/endocrine homeostasis and attenuates the susceptibility of pulmonary infections.

A naphthalimide-based turn-on fluorescence probe for peroxynitrite detection and imaging in living cells

Peroxynitrite (ONOO⁻) is a potent biological oxidant that plays a significant role in diverse physiological and pathological processes. A novel fluorescent probe HCA-OH was developed for specific and sensitive detection of peroxynitrite, and displayed a significant fluorescence turn-on signal. With low cytotoxicity and good photostability, the probe HCA-OH could be applied in imaging ONOO⁻ distribution in HepG2 cells and live C. elegans in real time. Therefore, the probe can be a promising tool for imaging in vivo.

A novel fluorescent probe HCA-OH was designed for selective detection of peroxynitrite and imaging in HepG2 cells and C. elegans.

Mitochondrial superoxide anions induced by exogenous oxidative stress determine tumor cell fate: an individual cell-based study

OBJECTIVE

Reactive oxygen species (ROS) are involved in a variety of biological phenomena and serve both deleterious and beneficial roles. ROS quantification and assessment of reaction networks are desirable but difficult because of their short half-life and high reactivity. Here, we describe a pro-oxidative model in a single human lung carcinoma SPC-A-1 cell that was created by application of extracellular H₂O₂ stimuli.

METHODS

Modified microfluidics and imaging techniques were used to determine O₂ ^•- levels and construct an O₂ ^•- reaction network. To elucidate the consequences of increased O₂ ^•- input, the mitochondria were given a central role in the oxidative stress mode, by manipulating mitochondria-interrelated cytosolic Ca²⁺ levels, mitochondrial Ca²⁺ uptake, auto-amplification of intracellular ROS and the intrinsic apoptotic pathway.

RESULTS AND CONCLUSIONS

Results from a modified microchip demonstrated that 1 mmol/L H₂O₂ induced a rapid increase in cellular O₂ ^•- levels (>27 vs. >406 amol in 20 min), leading to increased cellular oxidizing power (evaluated by ROS levels) and decreased reducing power (evaluated by glutathione (GSH) levels). In addition, we examined the dynamics of cytosolic Ca²⁺ and mitochondrial Ca²⁺ by confocal laser scanning microscopy and confirmed that Ca²⁺ stores in the endoplasmic reticulum were the primary source of H₂O₂-induced cytosolic Ca²⁺ bursts. It is clear that mitochondria have pivotal roles in determining how exogenous oxidative stress affects cell fate. The stress response involves the transfer of Ca²⁺ signals between organelles, ROS auto-amplification, mitochondrial dysfunction, and a caspase-dependent apoptotic pathway.

Purification and structural characterization of a novel natural pigment: cordycepene from edible and medicinal mushroom Cordyceps militaris

In the present work, a novel cordycepic pigment was successfully isolated and identified from Cordyceps militaris, as well as named as cordycepene (C₁₄H₁₇N₁O₄), according to the long unsaturated conjugated polyene structural characteristic. Cordycepene is sensitive to light, high temperature (≥ 60 °C), and acidic condition (pH ≤ 3), but possesses high stability against metal ions, and under alkaline and neutral conditions. Cordycepene shows a comparable DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging activity at higher concentration (≥ 2 mg/mL) to vitamin C. Cordycepene promotes the growth of HSF (human skin fibroblast cell) after incubation for 72 h, and has an ability to repair the UV light-treated HSF cells. In addition, cordycepene increases the antioxidant activity (SOD, superoxide dismutase; GSH-Px, glutathione peroxidase; CAT, catalase) and decreases MDA (malondialdehyde) level, indicating that cordycepene inhibits the photochemical senescence of HSF by enhancing the antioxidant defense system. The discovery of cordycepene can provide a basis for research on light incubation and the accumulation of yellow pigment (carotenoids) from C. militaris.

Organoselenotriazoles attenuate oxidative damage induced by mitochondrial dysfunction in mev-1 Caenorhabditis elegans mutants

Organic selenium compounds have several pharmacological activities already described, as anti-inflammatory and antitumor activities, which have been attributed to their antioxidant effects. Because they are promising in pharmacology, the synthesis of these compounds has increased significantly. As many new molecules are synthesized the use of a simple model like Caenorhabditis elegans is highly advantageous for initial evaluation of the toxicity and therapeutic potential of these molecules. The objective of this study was to evaluate the toxicity and antioxidant capacity of a series of selenotriazoles compounds in C. elegans. The animals were exposed to the compounds in liquid medium for only 30 min at the first larval stage (L1). The compounds had no toxic effects at the concentrations tested. Treatment with selenotriazoles (10 μM) partially reversed the stress induced by the pesticide paraquat (1 mM). Se-Tz Ia compound partially increased the survival of worms treated with H₂O₂ (0.5 mM). The compounds also increased the longevity of mev-1 mutants, which have a reduced life span by the production of excessive reactive oxygen species (ROS) in the mitochondria caused by a mutation in complex II of the electron transport chain. In addition, the compounds reduced the levels of ROS determined by the fluorescent probe DCF-DA as well as also reduced catalase enzyme activity in these animals. Based on the results found, it is possible to conclude that the compounds have antioxidant activity mainly in oxidative stress condition generated by a mitochondrial dysfunction in C. elegans.

Amplex Red Assay for Measuring Hydrogen Peroxide Production from Caenorhabditis elegans

Reagents such as Amplex^® Red have been developed for detecting hydrogen peroxide (H₂O₂) and are used to measure the release of H₂O₂ from biological samples such as mammalian leukocytes undergoing the oxidative burst. Caenorhabditis elegans is commonly used as a model host in the study of interactions with microbial pathogens and releases reactive oxygen species (ROS) as a component of its defense response. We adapted the Amplex^® Red Hydrogen Peroxide/Peroxidase Assay Kit to measure H₂O₂ output from live Caenorhabditis elegans exposed to microbial pathogens. The assay differs from other forms of ROS detection in the worm, like dihydrofluorescein dyes and genetically encoded probes such as HyPer, in that it generally detects released, extracellular ROS rather than intracellular ROS, though the distinction between the two is blurred by the fact that certain species of ROS, including H₂O₂, can cross membranes. The protocol involves feeding C. elegans on a lawn of the pathogen of interest for a period of time. The animals are then rinsed off the plates in buffer and washed to remove any microbes on their cuticle. Finally, the animals in buffer are distributed into 96-well plates and Amplex^® Red and horseradish peroxidase (HRP) are added. Any H₂O₂ released into the buffer by the worms will react with the Amplex^® Red reagent in a 1:1 ratio in the presence of HRP to produce the red fluorescent excitation product resorufin that can be measured fluorometrically or spectrophotometrically, and the amount of H₂O₂ released can be calculated by comparison to a standard curve. The assay is most appropriate for studies focused on released ROS, and its advantages include ease of use, the ability to use small numbers of animals in a plate reader assay in which measurements can be taken either fluorometrically or spectrophotometrically.

Genetic analysis of KillerRed in C. elegans identifies a shared role of calcium genes in ROS-mediated neurodegeneration

In C. elegans, neurodegeneration induced by excitotoxicity or aggregation of misfolded proteins is dependent on genes involved in calcium release from the endoplasmic reticulum. Reactive oxygen species (ROS) can also induce neurodegeneration, but the relationship between ROS-mediated neurodegeneration and calcium has not been established. We activated KillerRed in the GABA neurons of C. elegans to produce ROS that leads to functional loss and structural degeneration of these neurons and demonstrated that the severity of neurodegeneration was dependent on extent of KillerRed activation. To genetically examine the role of calcium in ROS-mediated neurodegeneration, we measured functional neurodegeneration in itr-1 (inositol trisphosphate receptor), crt-1 (caltreticulin), and unc-68 (ryanodine receptor) mutants. Similar to other neurotoxic conditions, neurodegeneration triggered by KillerRed was reduced in itr-1 and crt-1 mutants. Somewhat unexpectedly, genetic or pharmacological disruption of unc-68 had a minimal effect on neurodegeneration. Our results indicate ROS-mediated neurodegeneration occurs through a conserved calcium regulated mechanism and suggest that components of the degeneration process have different sensitivities to ROS.

Possible Involvement of Mitochondrial Dysfunction and Oxidative Stress in a Cellular Model of NAFLD Progression Induced by Benzo[a]pyrene/Ethanol CoExposure

Exposure to xenobiotics could favor the transition of nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis in obese patients. Recently, we showed in different models of NAFL that benzo[a]pyrene (B[a]P) and ethanol coexposure induced a steatohepatitis-like state. One model was HepaRG cells incubated with stearate and oleate for 2 weeks. In the present study, we wished to determine in this model whether mitochondrial dysfunction and reactive oxygen species (ROS) overproduction could be involved in the occurrence of this steatohepatitis-like state. CRISPR/Cas9-modified cells were also used to specify the role of aryl hydrocarbon receptor (AhR), which is potently activated by B[a]P. Thus, nonsteatotic and steatotic HepaRG cells were treated with B[a]P, ethanol, or both molecules for 2 weeks. B[a]P/ethanol coexposure reduced mitochondrial respiratory chain activity, mitochondrial respiration, and mitochondrial DNA levels and induced ROS overproduction in steatotic HepaRG cells. These deleterious effects were less marked or absent in steatotic cells treated with B[a]P alone or ethanol alone and in nonsteatotic cells treated with B[a]P/ethanol. Our study also disclosed that B[a]P/ethanol-induced impairment of mitochondrial respiration was dependent on AhR activation. Hence, mitochondrial dysfunction and ROS generation could explain the occurrence of a steatohepatitis-like state in steatotic HepaRG cells exposed to B[a]P and ethanol.

Reactive oxygen species and glutathione antioxidants in the testis of the soil biosentinel Podarcis sicula (Rafinesque 1810)

Important toxicological achievements have been made during the last decades using reptiles. We focus our investigation on gonadal reproductive health of the soil biosentinel Podarcis sicula which is very sensitive to endocrine-disrupting chemicals. The aim of this study is to quantitatively detect, by sensitive microassays, reactive oxygen species and the glutathione antioxidants in the testis and investigate if they are differentially expressed before and after remediation of a site of the "Land of Fires" (Campania, Italy) subject to illicit dumping of unknown material. The oxidative stress level was evaluated by electron spin resonance spectroscopy applying a spin-trapping procedure able to detect products of lipid peroxidation, DNA damage and repair by relative mobility shift, and poly(ADP-ribose) polymerase enzymatic activity, respectively, the expression of glutathione peroxidase 4 transcript by real-time quantitative PCR analysis, the antioxidant glutathione S-transferase, a well-assessed pollution index, by enzymatic assay and the total soluble antioxidant capacity. Experimental evidences from the different techniques qualitatively agree, thus confirming the robustness of the combined experimental approach. Collected data, compared to those from a reference unpolluted site constitute evidence that the reproductive health of this lizard is impacted by pollution exposure. Remediation caused significant reduction of reactive oxygen species and downregulation of glutathione peroxidase 4 mRNAs in correspondence of reduced levels of glutathione S-transferase, increase of antioxidant capacity, and repair of DNA integrity. Taken together, our results indicate directions to define new screening approaches in remediation assessment.

Novel procedures for whole organism detection and quantification of fluorescence as a measurement for oxidative stress in zebrafish (Danio rerio) larvae

The modes of action of pollutants are diverse, and a common consequences to pollutant exposure is oxidative stress. This phenomenon is caused by an imbalance or disurption in the control of Reactive Oxygen Species (ROS) resulting in an accumulation of free radicals. Oxidative stress may cause damages to the DNA, phospholipids and proteins, and lead to cell death. Due to the possible contribution of oxidative stress to pollutant toxicity, it is valuable to assess its occurrence, role and mechanism. Detection of oxidative stress at low concentrations soon after the onset of exposure can be a sensitive, general marker for contamination. This study aimed at developing and benchmarking a set of novel fluorescence-based procedures to assess the occurrence of oxidative stress in zebrafish larvae (96 hpf) by measuring the antioxidant glutathione (GSH) and general ROS. Zebrafish larvae were exposed to tert-butyl hydroperoxide (t-BHP). ROS and GSH were made visible by means of specific fluorescent molecular probes in different experimental scenarios. The induction was qualified using microscopy and quantified through photometric measurement. For quantitative assessment, an approach based on homogenized larvae and a non-invasive plate assay were developed. The novel procedures proved suitable for oxidative stress detection. Comparisons of qualitative to quantitative data showed that the orientation of the larvae in the well can influence fluorescence data evaluation. The non-invasive quantitative assay proved robust against any influence of the orientation of the larvae. The developed protocols promise to be useful tools for the detection of oxidative stress in zebrafish larvae.

Measurement of Intracellular ROS in Caenorhabditis elegans Using 2',7'-Dichlorodihydrofluorescein Diacetate

Reactive oxygen species (ROS) are generated during normal metabolic processes under aerobic conditions. Since ROS production initiates harmful radical chain reactions on cellular macromolecules, including lipid peroxidation, DNA mutation, and protein denaturation, it has been implicated in a wide spectrum of diseases such as cancer, cardiovascular disease, ischemia-reperfusion and aging. Over the past several decades, antioxidants have received explosive attention regarding their protective potential against these deleterious reactions. Accordingly, many analytical methodologies have been developed for the evaluation of the antioxidant capacity of compounds or complex biological samples. Herein, we introduce a simple and convenient method to detect in vivo intracellular ROS levels photometrically in Caenorhabditis elegans using 2',7'-dichlorofluorescein diacetate (H₂DCFDA), a cell permeant tracer.