Insights into the differential toxicological and antioxidant effects of 4-phenylchalcogenil-7-chloroquinolines in Caenorhabditis elegans

Caenorhabditis elegans as a Model for Evaluating the Toxicology of Inorganic Nanoparticles

Inorganic nanoparticles are nanomaterials with a central core composed of inorganic specimens, especially metals, which give them interesting applications but can impact the environment and human health. Their short- and long-term effects are not completely known and to investigate that, alternative models have been successfully used. Among these, the nematode Caenorhabditis elegans has been increasingly applied in nanotoxicology in recent years because of its many features and advantages for toxicological screening. This non-parasitic nematode may inhabit any environment where organic matter is available; therefore, it is interesting for ecotoxicological assessments. Moreover, this worm has a high genetic homology to humans, making the findings translatable. A notable number of published studies unraveled the level of toxicity of different nanoparticles, including the mechanisms by which their toxicity occurs. This narrative review collects and describes the most relevant toxicological data for inorganic nanoparticles obtained using C. elegans and also supports its application in safety assessments for regulatory purposes.

Thioredoxin (Trx): A redox target and modulator of cellular senescence and aging-related diseases

Thioredoxin (Trx) is a compact redox-regulatory protein that modulates cellular redox state by reducing oxidized proteins. Trx exhibits dual functionality as an antioxidant and a cofactor for diverse enzymes and transcription factors, thereby exerting influence over their activity and function. Trx has emerged as a pivotal biomarker for various diseases, particularly those associated with oxidative stress, inflammation, and aging. Recent clinical investigations have underscored the significance of Trx in disease diagnosis, treatment, and mechanistic elucidation. Despite its paramount importance, the intricate interplay between Trx and cellular senescence-a condition characterized by irreversible growth arrest induced by multiple aging stimuli-remains inadequately understood. In this review, our objective is to present a comprehensive and up-to-date overview of the structure and function of Trx, its involvement in redox signaling pathways and cellular senescence, its association with aging and age-related diseases, as well as its potential as a therapeutic target. Our review aims to elucidate the novel and extensive role of Trx in senescence while highlighting its implications for aging and age-related diseases.

In silico evidences of Mpro inhibition by a series of organochalcogen-AZT derivatives and their safety in Caenorhabditis elegans

BACKGROUND

The new coronavirus (SARS-CoV-2) pandemic emerged in 2019 causing millions of deaths. Vaccines were quickly developed and made available in 2021. Despite the availability of vaccines, some subjects refuse to take the immunizing or present comorbities, therefore developing serious cases of COVID-19, which makes necessary the development of antiviral drugs. Previous studies have demonstrated that ebselen, a selenium-containing molecule, can inhibit SARS-CoV-2 Mpro. In addition, selenium is a trace element that has antiviral and anti-inflammatory properties. Zidovudine (AZT) has been widely used against HIV infections and its action against SARS-CoV-2 may be altered by the structural modification with organochalcogen moieties, but this hypothesis still needs to be tested.

METHODS

In the present work we evaluated the Mpro inhibition capacity (in silico), the safety and antioxidant effect of six organochalcogen AZT-derivatives using the free-living nematode Caenorhabditis elegans, through acute (30 min) and chronic (48) exposure protocols.

RESULTS

We observed that the molecules were safe at a concentration range of 1-500 µM and did not alter any toxicological endpoint evaluated. Furthermore, the molecules are capable to decrease the ROS formation stimulated by hydrogen peroxide, to modulate the expression of important antioxidant enzymes such superoxide-dismutase-3 and glutathione S-transferese-4 and to stimulate the translocation of the DAF-16 to the cell nucleus. In addition, the molecules did not deplete thiol groups, which reinforces their safety and contribution to oxidative stress resistance.

CONCLUSIONS

We have found that compounds S116l (a Tellurium AZT-derivative) and S116h (a Selenium-AZT derivative) presented more promising effects both in silico and in vivo, being strong candidates for further in vivo studies.

Campomanesia adamantium O Berg. fruit, native to Brazil, can protect against oxidative stress and promote longevity

Campomanesia adamantium O. Berg. is a fruit tree species native to the Brazilian Cerrado biome whose fruits are consumed raw by the population. The present study determined the chemical composition of the C. adamantium fruit pulp (FPCA) and investigated its in vitro antioxidant potential and its biological effects in a Caenorhabditis elegans model. The chemical profile obtained by LC-DAD-MS identified 27 compounds, including phenolic compounds, flavonoids, and organic carboxylic acids, in addition to antioxidant lipophilic pigments and ascorbic acid. The in vitro antioxidant activity was analysed by the radical scavenging method. In vivo, FPCA showed no acute reproductive or locomotor toxicity. It promoted protection against thermal and oxidative stress and increased the lifespan of C. elegans. It also upregulated the antioxidant enzymes superoxide dismutase and glutathione S-transferase and activated the transcription factor DAF-16. These results provide unprecedented in vitro and in vivo evidence for the potential functional use of FPCA in the prevention of oxidative stress and promotion of longevity.

Development and In Vivo Assessment of 4-Phenyltellanyl-7-chloroquinoline-loaded Polymeric Nanocapsules in Alzheimer's Disease Models

Alzheimer's disease (AD) is the most common form of dementia in older people, and available treatments are palliative and produce undesirable side effects. The 4-phenyltellanyl-7-chloroquinoline (TQ) is an organochalcogen compound studied due to its pharmacological properties, particularly its antioxidant potential. However, TQ possesses some drawbacks such as low aqueous solubility and high toxicity, thus warranting the search for tools that improve the safety and effectiveness of new compounds. Here, we developed and investigated the biological effects of TQ-loaded polymeric nanocapsules (NCTQ) in an AD model in transgenic Caenorhabditis elegans expressing human Aβ_1-42 in their body-wall muscles and Swiss mice injected with Aβ_25-35. The NCTQ displayed good physicochemical properties, including nanometer size and maximum encapsulation capacity. The treatment showed low toxicity, reduced Aβ peptide-induced paralysis, and activated an endoplasmic reticulum chaperone in the C. elegans model. The Aβ injection in mice caused memory impairment, which NCTQ mitigated by improving working, long-term, and aversive memory. Additionally, no changes in biochemical markers were evidenced in mice, demonstrating that there was no hepatotoxicity in the tested doses. Altogether, these findings provide insights into the neuroprotective effects of TQ and indicate that NCTQ is a promising candidate for AD treatment.

Elucidation of the nematicidal mode of action of grammicin on Caenorhabditis elegans

Grammicin (Gra) is derived from the endophytic fungus Xylaria grammica EL000614 and shows nematicidal activity against the devastating root-knot nematode Meloidogyne incognita in-vitro, in planta, and in-field experiments. However, the mechanism of the nematicidal action of Gra remains unclear. In this study, Gra exposure to the model genetic organism Caenorhabditis elegans affected its L1, L2/3, L4, and young adult stages. In addition, Gra treatment increased the intracellular reactive oxygen species (ROS) levels of C. elegans and M. incognita. Molecular docking interaction analysis indicated that Gra could bind and interact with GCS-1, GST-4, and DAF-16a in order of low binding energy, followed by SOD-3, SKN-1, and DAF-16b. This implies that the anthelmintic action of Gra is related to the oxidative stress response. To validate this mechanism, we examined the expression of the genes involved in the oxidative stress responses following treatment with Gra using transgenic C. elegans strains such as the TJ356 strain zIs356 [daf-16p::daf-16a/b::GFP + rol-6 (su1006)], LD1 ldIs7 [skn-1p::skn-1b/c::GFP + rol-6 (su1006)], LD1171 ldIs3 [gcs-1p::GFP + rol-6 (su1006)], CL2166 dvIs19 [(pAF15) gst-4p::GFP::NLS], and CF1553 strain muIs84 [(pAD76) sod-3p::GFP + rol-6 (su1006)]. Gra treatment caused nuclear translocation of DAF-16/FoxO and enhanced gst-4::GFP expression, but it had no change in sod-3::GFP expression. These results indicate that Gra induces oxidative stress response via phase II detoxification without reduced cellular redox machinery. Gra treatment also inhibited the nuclear localization of SKN-1::GFP in the intestine, which may lead to a condition in which oxidative stress tolerance is insufficient to protect C. elegans by the inactivation of SKN-1, thus inducing nematode lethality. Furthermore, Gra caused the mortality of two mutant strains of C. elegans, CB113 and DA1316, which are resistant to aldicarb and ivermectin, respectively. This indicates that the mode of action of Gra is different from the traditional nematicides currently in use, suggesting that it could help develop novel approaches to control plant-parasitic nematodes.

In vivo Assessment of Cold Atmospheric Pressure Plasma Technology on the Bioactivity of Spirulina

The present study challenges the in vivo assessment of cold atmospheric pressure plasma (CAPP) technology on the bioactive activity (antioxidant/antiaging and antimicrobial potential) of Spirulina powder, using Caenorhabditis elegans as an animal model. Surface microdischarge cold atmospheric pressure plasma (SMD-CAPP) treatment was 3.3 W discharge power for 7 min. C. elegans lifespan and egg laying were used as indicators of antioxidant/antiaging potential of Spirulina (1 mg/mL), when grown with Spirulina CP-treated [E_SCP] and untreated [E_S], compared with a control [E_0] (non-supplemented with Spirulina). According to our results, under both Spirulina supplemented media [E_SCP and E_S] and for the first 17 days, nematodes experienced an increase in lifespan but without significant differences (p > 0.05) between control and Spirulina CP-treated. Regarding the in vivo assay of the antimicrobial potential of Spirulina against Salmonella enterica serovar Typhimurium (infected worms), no significant differences (p > 0.05) were found between the three exposure scenarios (control [S_0]; Spirulina supplemented media [S_S]; CP-treated Spirulina supplemented media [S_SCP]). According to present results, CAPP-treatment do not influence negatively the lifespan of C. elegans but a reduction in the Spirulina antiaging potential was found. No in vivo modifications in antimicrobial activity seem to be linked to CAPP-processed Spirulina.

Interface of Aging and Acute Peripheral Neuropathy Induced by Oxaliplatin in Mice: Target-Directed Approaches for Na+, K+-ATPase, Oxidative Stress, and 7-Chloro-4-(phenylselanyl) quinoline Therapy

Almost 90% of patients develop pain immediately after oxaliplatin (OXA) treatment. Here, the impact of aging on OXA-induced acute peripheral neuropathy and the potential of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) as a new therapeutic strategy were evaluated. In Swiss mice, the oxidative damage and its influence on Mg²⁺-ATPase and Na⁺, K⁺-ATPase activities were investigated. The relationship between the reactive oxygen species (ROS) and nitrate and nitrite (NOx) levels, the activity of glutathione peroxidase (GPx), and superoxide dismutase (SOD) with the development of OXA-induced acute peripheral neuropathy was also studied. In this study, it was evidenced that OXA-induced acute peripheral neuropathy was exacerbated by aging through increased oxidative damage as well as Na⁺, K⁺-ATPase, and Mg⁺²-ATPase inhibition. 4-PSQ reversed hypersensitivity induced by OXA and aging-aggravated by reducing ROS and NOx levels, through modulation of GPx and SOD activities. 4-PSQ partially reestablish Na⁺, K⁺-ATPase activity, but not Mg ²⁺-ATPase activity. Locomotor and exploratory activities were not affected. This study is the first of its kind, providing new insight into the aging impact on mechanisms involved in OXA-induced acute peripheral neuropathy. Also, it provides evidence on promising 4-PSQ effects on this condition, mainly on aging.

Rodrigues K, Pinz MP, Biondi JV, Becker NP, Blodorn E, Domingues WB, Larroza A, Campos VF, Alves D, Wilhelm EA, Luchese C. Prospecting for a quinoline containing selenium for comorbidities depression and memory impairment induced by restriction stress in mice

RATIONALE

Depression is often associated with memory impairment, a clinical feature of Alzheimer's disease (AD), but no effective treatment is available. 7-Chloro-4-(phenylselanyl) quinoline (4-PSQ) has been studied in experimental models of diseases that affect the central nervous system.

OBJECTIVES

The pharmacological activity of 4-PSQ in depressive-like behavior associated with memory impairment induced by acute restraint stress (ARS) in male Swiss mice was evaluated.

METHODS

ARS is an unavoidable stress model that was applied for a period of 240 min. Ten minutes after ARS, animals were intragastrically treated with canola oil (10 ml/kg) or 4-PSQ (10 mg/kg) or positive controls (paroxetine or donepezil) (10 mg/kg). Then, after 30 min, mice were submitted to behavioral tests. Corticosterone levels were evaluated in plasma and oxidative stress parameters; monoamine oxidase (MAO)-A and MAO -B isoform activity; mRNA expression levels of kappa nuclear factor B (NF-κB); interleukin (IL)-1β, IL-18, and IL-33; phosphatidylinositol-se-kinase (PI3K); protein kinase B (AKT2), as well as acetylcholinesterase activity were evaluated in the prefrontal cortex and hippocampus.

RESULTS

4-PSQ attenuated the depressive-like behavior, self-care, and memory impairment caused by ARS. Based on the evidence, we believe that effects of 4-PSQ may be associated, at least in part, with the attenuation of HPA axis activation, attenuation of alterations in the monoaminergic system, modulation of oxidative stress, reestablishment of AChE activity, modulation of the PI3K/AKT2 pathway, and reduction of neuroinflammation.

CONCLUSIONS

These results suggested that 4-PSQ exhibited an antidepressant-like effect and attenuated the memory impairment induced by ARS, and it is a promising molecule to treat these comorbidities.

Synthesis of 4-Arylselanyl-1H-1,2,3-triazoles from Selenium-Containing Carbinols

In this work, we present a simple way to achieve 4-arylselanyl-1H-1,2,3-triazoles from selenium-containing carbinols in a one-pot strategy. The selenium-containing carbinols were used as starting materials to produce a range of selanyl-triazoles in moderate to good yields, including a quinoline and Zidovudine derivatives. One-pot protocols are crucial to the current concerns about waste production and solvent consumption, avoiding the isolation and purification steps of the reactive terminal selanylalkynes. We could also isolate an interesting and unprecedented by-product with one alkynylselenium moiety connected to the triazole.

Conjugates of desferrioxamine and aromatic amines improve markers of iron-dependent neurotoxicity

Alzheimer's Disease (AD) is a complex neurodegenerative disorder associated in some instances with dyshomeostasis of redox-active metal ions, such as copper and iron. In this work, we investigated whether the conjugation of various aromatic amines would improve the pharmacological efficacy of the iron chelator desferrioxamine (DFO). Conjugates of DFO with aniline (DFOANI), benzosulfanylamide (DFOBAN), 2-naphthalenamine (DFONAF) and 6-quinolinamine (DFOQUN) were obtained and their properties examined. DFOQUN had good chelating activity, promoted a significant increase in the inhibition of β-amyloid peptide aggregation when compared to DFO, and also inhibited acetylcholinesterase (AChE) activity both in vitro and in vivo (Caenorhabditis elegans). These data indicate that the covalent conjugation of a strong iron chelator to an AChE inhibitor offers a powerful approach for the amelioration of iron-induced neurotoxicity symptoms.

Non-targeted metabolomic profiling of atrazine in Caenorhabditis elegans using UHPLC-QE Orbitrap/MS

The widespread use of the herbicides Atrazine (ATR) has been raised attention due to its ubiquitous occurrence in the environment. As an endocrine disruptor, ATR causes reproductive, immune, nervous system toxicity in biota. In this study, we aimed to investigate metabolic profile characteristics and potential metabolic biomarker that reflects specific damage in toxic effect after ATR exposure. Hence, a metabolomics study was performed to determine the significantly affected metabolites and the reproduction and locomotion of C. elegans were investigated. Mediation analysis was used to evaluate the mediating effect of metabolites on association between ATR exposure and toxic effect. ATR (≥0.04 mg/L) caused the significant dose dependent reduction of brood size and locomotion behavior, however, the body length and width were significantly decreased only in 40 mg/L group. These results suggesting that brood size, head thrashes and body bends are more sensitive indictor to assessment ATR toxicity in C. elegans. Meanwhile, metabolomics analysis revealed that ATR exposure can induce metabolic profiles significant alterations in C. elegans. We found that 9 metabolites significantly increased and 18 metabolites significantly decreased, such as phosphatidylcholine, GMP, CDP-choline, neopterin etc. Those alteration of metabolites were mainly involved in the pathways: glycerophospholipid metabolism, glycolysis/gluconeogenesis, folate biosynthesis, glycine, serine and threoninemetabolism, pyrimidine and purine metabolism. Overall, these changes are signs of possible oxidative stress and ATP synthesis disruption modification. Mediation analysis showed a significant indirect effect of ATR exposure on brood size, via 7,8-dihydroneopterin 2',3'-cyclic-p, and phosphatidylcholine might mediate association between ATR exposure and body bends, suggesting that 7,8-dihydroneopterin 2',3'-cyclic-p and phosphatidylcholine might be potentially specificity marker for brood size and body bend respectively. This preliminary analysis investigates metabolic characteristics in C. elegans after ATR exposure, helping to understand the pathways involved in the response to ATR exposure and provide potential biomarkers for the safety evaluation of ATR.

Bacteria metabolites from Peganum harmala L. polysaccharides inhibits polyQ aggregation through proteasome-mediated protein degradation in C. elegans

Huntington's disease (HD) is a relentlessly progressive neurodegenerative disease featured by the over-expanded polyglutamine (polyQ)-induced protein aggregation. Using Caenorhabditis elegans (C. elegans) as a model system, we show that water soluble polysaccharide extracted from the herb Peganum harmala L. (PS1) not only reduces polyQ aggregation but also alleviates the associated neurotoxicity. Genetic and pharmacologic analysis suggested that PS1 treatment acts though proteasome-mediated protein degradation pathway to inhibit polyQ aggregation. Notably, the efficacy of PS1 is aroused specifically by co-incubation with live Escherichia coli OP50, which is the sole food source for worms. Further UPLC-Q-TOF/MS analysis determined the bioactivity of polyQ inhibition, which is composed of several oligosaccharides, including stachyoses, verbascoses, trisaccharides and tetrasaccharides composed of galacturonic acids. Together, our study revealed a potential drug target for further HD treatment and pinpointed the possibility that the secreted metabolites produced from bacteria treated with various compounds may provide direct beneficial effect to human bodies.

Activation of SOD-3 is involved in the antioxidant effect of a new class of β-aryl-chalcogenium azide compounds in Caenorhabditis elegans

Organic selenium, tellurium and sulfur compounds have been studied due to their pharmacological properties. For instance, the β-aryl-chalcogenium azide compounds have demonstrated antitumoral action in vitro. However, yet no pharmacological actions of this class of compounds were determined in vivo. Caenorhabditis elegans is a nematode that presents innumerable advantages in relation to mammalian models, such as having a small and transparent body, which allows the visualization of its internal anatomy, besides short life and low cost. Based on that, the aim of this work was to investigate the pharmacological and toxicological properties of β-aryl-chalcogenium azide compounds in C. elegans. As well, to evaluate the capacity of organochalcogenium compounds to repair oxidative damage induced by hydrogen peroxide and the possible mechanism of action of these compounds using CF1553 transgenic strain with superoxide dismutase (SOD-3) tagged with GFP. Our results showed that β-aryl-chalcogenium azide have low toxicity in wild-type worms and the pre-treatment protected against the damage induced by hydrogen peroxide at higher tested concentration. Associated with this, we observed that this protection is due in part to the increased expression of the antioxidant enzyme SOD-3. In conclusion, β-aryl-chalcogenium azide compounds caused low toxicity and induced stress-resistance by modulating SOD-3 expression in C. elegans.

Advances in the Understanding of Oxaliplatin-Induced Peripheral Neuropathy in Mice: 7-Chloro-4-(Phenylselanyl) Quinoline as a Promising Therapeutic Agent

In this study, the deposition of platinum in oxaliplatin (OXA)-exposed mice and the effects of the oxidative damage on the central nervous system were investigated. The relationship between the reactive species (RS) levels as well as the expression and activity of enzymes, such as catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD) and acetylcholinesterase (AChE), in the development of peripheral neuropathy after OXA exposure, was evidenced. The effects of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) on OXA-induced peripheral neuropathy was also investigated. Swiss mice received OXA (10 mg kg^-1) or vehicle by intraperitoneal route (days 0 and 2). Oral administration of 4-PSQ (1 mg kg^-1) or vehicle was performed on days 2 to 14. Behavioural tasks started on day 9, after the first OXA administration. It was observed that 4-PSQ reduced the mechanical and thermal hypersensitivity induced by OXA. 4-PSQ and OXA did not affect locomotor and exploratory activities. The results revealed, for the first time, a high concentration of platinum in the spinal cord of mice exposed to OXA. 4-PSQ reversed the increased levels of RS in the spinal cord, cerebral cortex and hippocampus of mice exposed to OXA. The alterations in the activity and expression of the GPx, SOD, CAT and AChE induced by OXA exposure were normalized by 4-PSQ. Therefore, the 4-PSQ might be a good prototype for the development of a more effective drug for the treatment of OXA-induced peripheral neuropathy. The results obtained by the present study expanded the knowledge about the mechanisms involved in the physiopathology of peripheral neuropathy. Graphical abstract.

Synthesis and antioxidant activity of new selenium-containing quinolines

Background:

Quinoline derivatives have been attracted much attention in drug discovery and synthetic derivatives of these scaffolds present a range of pharmacological activities. Therefore, organoselenium compounds are valuable scaffolds in organic synthesis because their pharmacological activities and their use as versatile building blocks for regio-, chemio-and stereoselective reactions. Thus, the synthesis of selenium-containing quinolines has great significance, and their applicability range from simple antioxidant agents, to selective DNA-binding and photocleaving agents.

Objective:

In the present study we describe the synthesis and antioxidant activity in vitro of new 7-chloroN(arylselanyl)quinolin-4-amines 5 by the reaction of 4,7-dichloroquinoline 4 with (arylselanyl)-amines 3.

Methods:

For the synthesis of 7-chloro-N(arylselanyl)quinolin-4-amines 5, we performed the reaction of (arylselanyl)- amines 3 with 4,7-dichloroquinoline 4 in the presence of Et3N at 120 °C in a sealed tube. The antioxidant activities of the compounds 5 were evaluated by the following in vitro assays: 2,2- diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric ion reducing antioxidant power (FRAP), nitric oxide (NO) scavenging and superoxide dismutase-like activity (SOD-Like).

Results:

7-Chloro-N(arylselanyl)quinolin-4-amines 5a-d has been synthesized in yields ranging from 68% to 82% by the reaction of 4,7-dichloroquinoline 4 with arylselanyl-amines 3a-d using Et3N as base, at 120 °C, in a sealed tube for 24 hours and tolerates different substituents, such as -OMe and -Cl, in the arylselanyl moiety. The obtained compounds 5a-d presented significant results with respect to the antioxidant potential, which had effect in the tests of inhibition of radical’s DPPH, ABTS+ and NO, as well as in the test that evaluates the capacity (FRAP) and in the superoxide dismutase-like activity assay (SOD-Like). It is worth mentioning that 7-chloro-N(arylselanyl)quinolin-4-amine 5b presented excellent results, demonstrating a better antioxidant capacity when compared to the others.

Conclusion:

According to the obtained results 7-chloro-N(arylselanyl)quinolin-4-amines 5 were synthesized in good yields by the reaction of 4,7-dichloroquinoline with arylselanyl-amines and tolerates different substituents in the arylselanyl moiety. The tested compounds presented significant antioxidant potential in the tests of inhibition of DPPH, ABTS+ and NO radicals, as well as in the FRAP and superoxide dismutase-like activity assays (SOD-Like).

Stability of di-butyl-dichalcogenide-capped gold nanoparticles: experimental data and theoretical insights

Metals capped with organochalcogenides have attracted considerable interest due to their practical applications, which include catalysis, sensing, and biosensing, due to their optical, magnetic, electrochemical, adhesive, lubrication, and antibacterial properties. There are numerous reports of metals capped with organothiol molecules; however, there are few studies on metals capped with organoselenium or organotellurium. Thus, there is a gap to be filled regarding the properties of organochalcogenide systems which can be improved by replacing sulfur with selenium or tellurium. In the last decade, there has been significant development in the synthesis of selenium and tellurium compounds; however, it is difficult to find commercial applications of these compounds because there are few studies showing the feasibility of their synthesis and their advantages compared to organothiol compounds. Stability against oxidation by molecular oxygen under ambient conditions is one of the properties which can be improved by choosing the correct organochalcogenide; this can confer important advantages for many more suitable applications. This paper reports the successful synthesis and characterization of gold nanoparticles functionalized with organochalcogenide molecules (dibutyl-disulfide, dibutyl-diselenide and dibutyl-ditelluride) and evaluates the oxidation stability of the organochalcogenides. Spherical gold nanoparticles with diameters of 24 nm were capped with organochalcogenides and were investigated using X-ray photoelectron spectroscopy (XPS) to show the improved stability of organoselenium compared with organothiol and organotellurium. The results suggest that the organoselenium is a promising candidate to replace organothiol because of its enhanced stability towards oxidation by molecular oxygen under ambient conditions and its slow oxidation rate. The observed difference in the oxidation processes, as discussed, is also in agreement with theoretical calculations.

Diphenyl diselenide protects a Caenorhabditis elegans model for Huntington's disease by activation of the antioxidant pathway and a decrease in protein aggregation

The effect of (PhSe)₂ in a C. elegans model for Huntington's disease. Treatment with (PhSe)₂ triggered the nuclear translocation and activation of DAF-16 transcription factor in C. elegans, inducing the expression of superoxide dismutase-3 (SOD-3) and heat shock protein-16.2 (HSP-16.2). SOD-3 acts on reactive oxygen species (ROS) detoxification, and HSP-16.2 decreases protein misfolding and aggregation, which occur in HD.

Synthesis, photophysics and biomolecule interactive studies of new hybrid benzo-2,1,3-thiadiazoles

New hybrid molecules containing benzo-2,1,3-thiadiazole, benzofuran and arylselanyl moieties were synthesized and their photophysics and biomolecule interactive studies were performed.

Melatonin-loaded lipid-core nanocapsules protect against lipid peroxidation caused by paraquat through increased SOD expression in Caenorhabditis elegans

BACKGROUND

Melatonin has been described in the literature as a potent antioxidant. However, melatonin presents variable, low bioavailability and a short half-life. The use of polymeric nanoparticulated systems has been proposed for controlled release. Thus, the purpose of this study was to investigate the action of melatonin-loaded lipid-core nanocapsules (Mel-LNC) in the antioxidant system of Caenorhabditis elegans, and the possible protective effect of this formulation against lipid peroxidation caused by paraquat (PQ).

METHODS

The suspensions were prepared by interfacial deposition of the polymer and were physiochemically characterized. C. elegans N2 wild type and transgenic worm CF1553, muls84 [sod-3p::gfp; rol6(su1006)] were obtained from the Caenorhabditis Genetics Center (CGC). The worms were divided into 5 groups: Control, PQ 0.5 mM, PQ 0.5 mM + Mel-LNC 10 μg/mL, PQ + unloaded lipid-core nanocapsules (LNC), and PQ + free melatonin (Mel) 10 μg/mL. The lipid peroxidation was assessed through thiobarbituric acid (TBARS) levels and the fluorescence levels of the transgenic worms expressing GFP were measured.

RESULTS

The LNC and Mel-LNC presented a bluish-white liquid, with pH values of 5.56 and 5.69, respectively. The zeta potential was - 6.4 ± 0.6 and - 5.2 ± 0.2, respectively. The mean particle diameter was 205 ± 4 nm and 203 ± 3 nm, respectively. The total melatonin content was 0.967 mg/ml. The TBARS levels were significantly higher in the PQ group when compared to the control group (p < 0.001). Mel-LNC reduced TBARS levels to similar levels found in the control group. Moreover, only Mel-LNC significantly enhanced the SOD-3 expression (p < 0.05). Mel-LNC was capable of protecting C. elegans from lipid peroxidation caused by PQ and this was not observed when free melatonin was used. Moreover, Mel-LNC increased the fluorescence intensity of the transgenic strain that encodes the antioxidant enzyme SOD-3, demonstrating a possible mechanism of protection from PQ-induced damage.

CONCLUSION

These findings demonstrated that melatonin, when associated with nanocapsules, had improved antioxidant properties and the protective activity against PQ-induced lipid peroxidation could be associated with the activation of antioxidant enzymes by Mel-LNC in C. elegans.

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.

Treatment of Caenorhabditis elegans with Small Selenium Species Enhances Antioxidant Defense Systems

SCOPE

Small selenium (Se) species play a key role in Se metabolism and act as dietary sources of the essential trace element. However, they are redox-active and trigger pro- and antioxidant responses. As health outcomes are strongly species-dependent, species-specific characteristics of Se compounds are tested in vivo.

METHODS AND RESULTS

In the model organism Caenorhabditis elegans (C. elegans), immediate and sustained effects of selenite, selenomethionine (SeMet), and Se-methylselenocysteine (MeSeCys) are studied regarding their bioavailability, incorporation into proteins, as well as modulation of the cellular redox status. While all tested Se compounds are bioavailable, only SeMet persistently accumulates and is non-specifically incorporated into proteins. However, the protection toward chemically-induced formation of reactive species is independent of the applied Se compound. Increased thioredoxin reductase (TXNRD) activity and changes in mRNA expression levels of antioxidant proteins indicate the activation of cellular defense mechanisms. However, in txnrd-1 deletion mutants, no protective effects of the Se species are observed anymore, which is also reflected by differential gene expression data.

CONCLUSION

Se species protect against chemically-induced reactive species formation. The identified immediate and sustained systemic effects of Se species give rise to speculations on possible benefits facing subsequent periods of inadequate Se intake.

The glutathione system and the related thiol network in Caenorhabditis elegans

Advances in the field of redox biology have contributed to the understanding of the complexity of the thiol-based system in mediating signal transduction. The redox environment is the overall spatiotemporal balance of oxidation-reduction systems within the integrated compartments of the cell, tissues and whole organisms. The ratio of the reduced to disulfide glutathione redox couple (GSH:GSSG) is a key indicator of the redox environment and its associated cellular health. The reaction mechanisms of glutathione-dependent and related thiol-based enzymes play a fundamental role in the function of GSH as a redox regulator. Glutathione homeostasis is maintained by the balance of GSH synthesis (de novo and salvage pathways) and its utilization through its detoxification, thiol signalling, and antioxidant defence functions via GSH-dependent enzymes and free radical scavenging. As such, GSH acts in concert with the entire redox network to maintain reducing conditions in the cell. Caenorhabditis elegans offers a simple model to facilitate further understanding at the multicellular level of the physiological functions of GSH and the GSH-dependent redox network. This review discusses the C. elegans studies that have investigated glutathione and related systems of the redox network including; orthologs to the protein-encoding genes of GSH synthesis; glutathione peroxidases; glutathione-S-transferases; and the glutaredoxin, thioredoxin and peroxiredoxin systems.

7-Chloro-4-(Phenylselanyl) Quinoline with Memory Enhancer Action in Aging Rats: Modulation of Neuroplasticity, Acetylcholinesterase Activity, and Cholesterol Levels

This study investigated the effect of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) to restore the cognitive impairment caused by aging in male Wistar rats. Moreover, modulation of neuroplasticity markers, acetylcholinesterase (AChE) activity, and cholesterol levels was performed. Aged rats were intragastrically treated with 4-PSQ (5 mg/kg) for 7 days. Animals were tested in behavioral tasks, and then plasma (to determine cholesterol levels), hippocampus, and cerebral cortex (to determine neural cell adhesion molecule (NCAM) and polysialyltransferase (PST) levels, and AChE activity) were removed. Our findings demonstrated that treatment of aged rats with 4-PSQ restored short-term and long-term memories in the object recognition tests. 4-PSQ treatment did not restore exploratory activity (rearings) but partially restored locomotor activity (crossings) reduced by aging in the open-field test. Moreover, the compound restored the reduction in the NCAM and PST levels, and AChE activity in cerebral structures, as well as the increase in the plasma cholesterol levels, caused by aging in rats. In conclusion, 4-PSQ restored cognitive impairment caused by aging in rats by modulating synaptic plasticity, cholinergic system, and cholesterol levels.

Neurotoxicity of nonylphenol exposure on Caenorhabditis elegans induced by reactive oxidative species and disturbance synthesis of serotonin

The present study was performed to evaluate the neurobehavioural deficit induced by nonylphenol (NP), a well-known xenobiotic chemical. The neurotoxic mechanism from oxidative stress and serotonin-related progress was also investigated. Caenorhabditis elegans was exposed at different levels of NP ranging from 0 to 200 μg L^-1 for 10 days. The results revealed that from a relatively low concentration (i.e., 10 μg L^-1), significant effects including decreased head thrashes, body bends and forging behaviour could be observed, along with impaired learning and memory behaviour plasticity. The level of reactive oxygen species (ROS) in head was significantly elevated with the increase of NP concentrations from 10 to 200 μg L^-1. Through antioxidant experiment, the oxidative damage caused by NP restored to some extent. At a NP concentration of 200 μg L^-1, the significant increased expression of stress-related genes, including sod-1, sod-3, ctl-2, ctl-3 and cyp-35A2 gene, was observed from integrated gene expression profiles. In addition, in comparison with wild-type N2 worms, the ROS accumulation was increased significantly with the mutation of sod-3. Tryptophan hydroxylase (TPH) in ADF and NSM neurons sharply decreased at the concentrations of 10-200 μg L^-1. The transcription of TPH synthesis-related genes and serotonin-related genes were both suppressed, including tph-1, cat-1, cat-4, ser-1, and mod-5. Overall, these results indicated that NP could induce neurotoxicity on Caenorhabditis elegans through excessive induction of ROS and disturbance synthesis of serotonin. The conducted research opened up new avenues for more effective exploration of neurotoxicity caused by NP.

Ilex paraguariensis modulates fat metabolism in Caenorhabditis elegans through purinergic system (ADOR-1) and nuclear hormone receptor (NHR-49) pathways

Ilex paraguariensis is a well-known plant that is widely consumed in South America, primarily as a drink called mate. Mate is described to have stimulant and medicinal properties. Considering the potential anti-lipid effects of I. paraguariensis infusion, we used an extract of this plant as a possible modulator of fat storage to control lipid metabolism in worms. Herein, the I. paraguariensis-dependent modulation of fat metabolism in Caenorhabditis elegans was investigated. C. elegans were treated with I. paraguariensis aqueous extract (1 mg/ml) from L1 larvae stage until adulthood, to simulate the primary form of consumption. Expression of adipocyte triglyceride lipase 1 (ATGL-1) and heat shock protein 16.2, lipid accumulation through C1-BODIPY-C12 (BODIPY) lipid staining, behavioral parameters, body length, total body energy expenditure and overall survival were analyzed. Total body energy expenditure was determined by the oxygen consumption rate in N2, nuclear hormone receptor knockout, nhr-49(nr2041), and adenosine receptor knockout, ador-1(ox489) strains. Ilex paraguariensis extract increased ATGL-1 expression 20.06% and decreased intestinal BODIPY fat staining 63.36%, compared with the respective control group, without affecting bacterial growth and energetic balance, while nhr-49(nr2041) and ador-1(ox489) strains blocked the worm fat loss. In addition, I. paraguariensis increased the oxygen consumption in N2 worms, but not in mutant strains, increased N2 worm survival following juglone exposure, and did not alter hsp-16.2 expression. We demonstrate for the first time that I. paraguariensis can decrease fat storage and increase body energy expenditure in worms. These effects depend on the purinergic system (ADOR-1) and NHR-49 pathways. Ilex paraguariensis upregulated the expression of ATGL-1 to modulate fat metabolism. Furthermore, our data corroborates with other studies that demonstrate that C. elegans is a useful tool for studies of fat metabolism and energy consumption.

Evaluation of antioxidant and neuroprotective activities of Cassia fistula (L.) using the Caenorhabditis elegans model

Background

Cassia fistula (L.) (Fabaceae) is a medicinal plant from tropical Asia. It is known for its marked antioxidant activity, which is attributed to its high phenolic content. The present study aims at testing both the antioxidant and neuroprotective effects of a hydroalcoholic extract from the aerial parts of Cassia fistula using the Caenorhabditis elegans model, which is widely used in this context.

Methods

Chemical profiling of secondary metabolites that seem to be responsible for both antioxidant and neuroprotective capacities was carried out by HPLC/PDA/ESI-MSⁿ. Antioxidant activity was tested in vitro by CUPRAC and DPPH assays. In vivo antioxidant and neuroprotective activities were investigated using the C. elegans model.

Results

The Cassia extract improved the survival rate of the nematodes and protected them against oxidative stress. In addition, a decrease in the accumulation of reactive oxygen species (ROS) was observed. The important role of DAF-16/FOXO pathway was confirmed through an increased nuclear localization of the DAF-16 transcription factor, increased expression of SOD-3 stress response gene and decreased expression of HSP-16.2. Furthermore, the putative involvement of SKN-1/NRF2 pathway was demonstrated by a decrease in GST-4 levels. A neuroprotective activity of the Cassia extract was shown by a decline in polyglutamine (polyQ40) aggregate formation and a delay in paralysis caused by amyloid beta (Aβ_1-42) accumulation.

Discussion

The Cassia extract exhibits substantial antioxidant and neuroprotective activities in vivo, which might provide a rich and novel source of natural antioxidants and neuroprotective compounds to be further studied for the use in various food and cosmetic industrial fields.

Effect of N-1 arylation of monastrol on kinesin Eg5 inhibition in glioma cell lines

An original and focused library of two sets of dihydropyrimidin-2-thiones (DHPMs) substituted with N-1 aryl groups derived from monastrol was designed and synthesized in order to discover a more effective Eg5 ligand than the template. Based on molecular docking studies, four ligands were selected to perform pharmacological investigations against two glioma cell lines. The results led to the discovery of two original compounds, called 20h and 20e, with an anti-proliferative effects, achieving IC50 values of about half that of the IC50 of monastrol in both cell lines. As with monastrol, flow cytometry analyses showed that the 20e and 20h compounds induced cell cycle arrest in the G2/M phase, and immunocytochemistry essays revealed the formation of monopolar spindles due to Eg5 inhibition without any toxicity to Caenorhabditis elegans.

S-allylmercapto-N-acetylcysteine protects against oxidative stress and extends lifespan in Caenorhabditis elegans

S-allylmercapto-N-acetylcysteine (ASSNAC) was shown in our previous study to activate Nrf2-mediated processes and increase glutathione level and resistance to oxidative stress in cultured endothelial cells. In this study, we explored the antioxidant protective effect of ASSNAC in Caenorhabditis elegans (C. elegans). Treatment of gst-4 reporter strain (CL2166) with increasing concentrations of ASSNAC (0.2 to 20 mM) for 24 hours and with ASSNAC (10 mM) for various time periods demonstrated a significant concentration- and time-dependent increase in Glutathione S-transferase (GST) gene expression (up to 60-fold at 20 mM after 24 hours). In addition, ASSNAC (2 mM; 24 hours) treatment of C. elegans strains N2 (wild type strain), gst-4 reporter (CL2166) and temperature sensitive sterile strain (CF512) significantly increased GST enzyme activity by 1.9-, 1.5- and 1.8-fold, respectively. ASSNAC (2.0 mM; 24 hours) increased the reduced glutathione content in N2 and CF512 strains by 5.9- and 4.9-fold, respectively. Exposure of C. elegans (N2 strain) to a lethal concentration of H₂O₂ (3.5 mM; 120 min) resulted in death of 88% of the nematodes while pretreatment with ASSNAC (24 hours) reduced nematodes death in a concentration-dependent manner down to 8% at 2.0 mM. C. elegans nematodes (strain CF512) cultured on agar plates containing ASSNAC (0.5 to 5.0 mM) demonstrated a significant increase in lifespan compared to control (mean lifespan 26.45 ± 0.64 versus 22.90 ± 0.59 days; log-rank p ≤ 0.001 at 2.0 mM) with a maximal lifespan of 40 versus 36 days. In conclusion, ASSNAC up-regulates the GST gene expression and enzyme activity as well as the glutathione content in C. elegans nematodes and thereby increases their resistance to oxidative stress and extends their lifespan.

Synthesis of symmetrical and unsymmetrical tellurides via silver catalysis

The cross-coupling reaction of diaryl ditellurides with aryl boronic acids is described using AgNO₃ as a catalyst.

Organoselenium compounds as mimics of selenoproteins and thiol modifier agents

Selenium is an essential trace element for animals and its role in the chemistry of life relies on a unique functional group: the selenol (-SeH) group. The selenol group participates in critical redox reactions. The antioxidant enzymes glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) exemplify important selenoproteins. The selenol group shares several chemical properties with the thiol group (-SH), but it is much more reactive than the sulfur analogue. The substitution of S by Se has been exploited in organic synthesis for a long time, but in the last 4 decades the re-discovery of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) and the demonstration that it has antioxidant and therapeutic properties has renovated interest in the field. The ability of ebselen to mimic the reaction catalyzed by GPx has been viewed as the most important molecular mechanism of action of this class of compound. The term GPx-like or thiol peroxidase-like reaction was previously coined in the field and it is now accepted as the most important chemical attribute of organoselenium compounds. Here, we will critically review the literature on the capacity of organoselenium compounds to mimic selenoproteins (particularly GPx) and discuss some of the bottlenecks in the field. Although the GPx-like activity of organoselenium compounds contributes to their pharmacological effects, the superestimation of the GPx-like activity has to be questioned. The ability of these compounds to oxidize the thiol groups of proteins (the thiol modifier effects of organoselenium compounds) and to spare selenoproteins from inactivation by soft-electrophiles (MeHg⁺, Hg²⁺, Cd²⁺, etc.) might be more relevant for the explanation of their pharmacological effects than their GPx-like activity. In our view, the exploitation of the thiol modifier properties of organoselenium compounds can be harnessed more rationally than the use of low mass molecular structures to mimic the activity of high mass macromolecules that have been shaped by millions to billions of years of evolution.