Interaction profile of diphenyl diselenide with pharmacologically significant thiols

Detection, detoxification, and removal of multiply heavy metal ions using a recyclable probe enabled by click and declick chemistry

The pollution of water with heavy metal ions has generated great concern among both the public and academics due to the high toxicity, persistence, and non-degradability of heavy metals. The detection, detoxification, and removal of heavy metal ions are critical for monitoring water quality and treating polluted water. However, these tasks remain challenging due to lack of effective detection, detoxification, and removal strategies. By combining thiol-triggered click chemistry and heavy metal ion-triggered declick chemistry, a recyclable fluorescent probe for detecting numerous heavy metal ions was successfully developed through simple addition of thiol-containing heavy metal antidote to a carefully selected Michael acceptor-type fluorophore. The probe could be regenerated by adding equal amount of antidote to the detection solution without any purification step recycled up to 10 times. The generated water-soluble heavy metal ion-antidote complexes showed weak toxicity to biological systems, indicating successful detoxification. Finally, a simple, economical, and practical device for detecting, detoxifying, and removing heavy metal ions was fabricated by loading the recyclable fluorescent probe into polymer beads. The percent of detection, and removal are 98.10% and 97.59%, respectively. And detoxification percent is as high as 65.55%. The device is a promising candidate for water quality monitoring and treatment.

Toxicology and pharmacology of synthetic organoselenium compounds: an update

Here, we addressed the pharmacology and toxicology of synthetic organoselenium compounds and some naturally occurring organoselenium amino acids. The use of selenium as a tool in organic synthesis and as a pharmacological agent goes back to the middle of the nineteenth and the beginning of the twentieth centuries. The rediscovery of ebselen and its investigation in clinical trials have motivated the search for new organoselenium molecules with pharmacological properties. Although ebselen and diselenides have some overlapping pharmacological properties, their molecular targets are not identical. However, they have similar anti-inflammatory and antioxidant activities, possibly, via activation of transcription factors, regulating the expression of antioxidant genes. In short, our knowledge about the pharmacological properties of simple organoselenium compounds is still elusive. However, contrary to our early expectations that they could imitate selenoproteins, organoselenium compounds seem to have non-specific modulatory activation of antioxidant pathways and specific inhibitory effects in some thiol-containing proteins. The thiol-oxidizing properties of organoselenium compounds are considered the molecular basis of their chronic toxicity; however, the acute use of organoselenium compounds as inhibitors of specific thiol-containing enzymes can be of therapeutic significance. In summary, the outcomes of the clinical trials of ebselen as a mimetic of lithium or as an inhibitor of SARS-CoV-2 proteases will be important to the field of organoselenium synthesis. The development of computational techniques that could predict rational modifications in the structure of organoselenium compounds to increase their specificity is required to construct a library of thiol-modifying agents with selectivity toward specific target proteins.

Effect of citrus peels-supplemented diet on longevity, memory index, redox status, cholinergic and monoaminergic enzymes in Drosophila melanogaster model

This study sought to determine the life span promoting effecof orange (Citrus sinensis), tangerine (Citrus maxima) and grapefruit (Citrus paradisi) peels in Drosophila melanogaster model. Flies (both gender, 3 to 5 days old) were divided into seven (7) groups (n = 5) containing 40 flies each; group I (control) flies were fed with basal diet, II-VII were flies were fed with basal diet containing 0.1 and 1.0% of tangerine peel (TP), orange peel (CP), and grapefruit peel (GP) respectively, for 14 days. Locomotor performance and memory index were assessed via negative geotaxis and aversive phototaxis suppression assays, respectively. Thereafter, the fly homogenates were assayed for activities of acetylcholinesterase (AChE), monoamine oxidase (MAO) and antioxidant enzymes as well as other indices of their redox. The results revealed that the citrus peels significantly improved longevity, locomotor performance, memory index, antioxidant status, and modulate cholinesterase and monoamine oxidase enzyme activities in treated flies when compared to the control. The results obtained suggest that the citrus peels offer potentials as dietary supplement with life span promoting properties in D. melanogaster model which could as well serve as a functional food additives. PRACTICAL APPLICATIONS: Citrus peels, although often considered agro-wastes, are used as food supplements and food ingredents especially in production of candies, jams and custards. This study suggests the use of orange (Citrus sinensis), tangerine (Citrus maxima), and grapefruit (Citrus paradisi) peels as dietary supplements which offers potential life span promoting properties.

The Se…S/N interactions as a possible mechanism of δ-aminolevulinic acid dehydratase enzyme inhibition by organoselenium compounds: A computational study

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DPDS and PSA interacts with cysteine residues from AlaD active site.

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The Se…S interactions could be involved in the δ-AlaD inhibition.

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δ-AlaD from Cucumis sativus does not present cysteine residues in the active site.

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Se…N interactions could be involved in the organoselenium action.

Organoselenium compounds present many pharmacological properties and are promising drugs. However, toxicological effects associated with inhibition of thiol-containing enzymes, such as the δ-aminolevulinic acid dehydratase (δ-AlaD), have been described. The molecular mechanism(s) by which they inhibit thiol-containing enzymes at the atomic level, is still not well known. The use of computational methods to understand the physical–chemical properties and biological activity of chemicals is essential to the rational design of new drugs. In this work, we propose an in silico study to understand the δ-AlaD inhibition mechanism by diphenyl diselenide (DPDS) and its putative metabolite, phenylseleninic acid (PSA), using δ-AlaD enzymes from Homo sapiens (Hsδ-AlaD), Drosophila melanogaster (Dmδ-AlaD) and Cucumis sativus (Csδ-AlaD). Protein modeling homology, molecular docking, and DFT calculations are combined in this study. According to the molecular docking, DPDS and PSA might bind in the Hsδ-AlaD and Dmδ-AlaD active sites interacting with the cysteine residues by Se^…S interactions. On the other hand, the DPDS does not access the active site of the Csδ-AlaD (a non-thiol protein), while the PSA interacts with the amino acids residues from the active site, such as the Lys291. These interactions might lead to the formation of a covalent bond, and consequently, to the enzyme inhibition. In fact, DFT calculations (mPW1PW91/def2TZVP) demonstrated that the selenylamide bond formation is energetically favored. The in silico data showed here are in accordance with previous experimental studies, and help us to understand the reactivity and biological activity of organoselenium compounds.

Sequential oxidations of phenylchalcogenides by H2O2: insights into the redox behavior of selenium via DFT analysis

The biological activity of sulfur and selenium, despite their similarity, shows some remarkable differences that have been recognized in many different scenarios.

Programmable hydrogels

Programmable hydrogels are defined as hydrogels that are able to change their properties and functions periodically, reversibly and/or sequentially on demand. They are different from those responsive hydrogels whose changes are passive or cannot be stopped or reversed once started and vice versa. The purpose of this review is to summarize major progress in developing programmable hydrogels from the viewpoints of principles, functions and biomedical applications. The principles are first introduced in three categories including biological, chemical and physical stimulation. With the stimulation, programmable hydrogels can undergo functional changes in dimension, mechanical support, cell attachment and molecular sequestration, which are introduced in the middle of this review. The last section is focused on the introduction and discussion of four biomedical applications including mechanistic studies in mechanobiology, tissue engineering, cell separation and protein delivery.

Mechanistic Insight into the Oxidation of Organic Phenylselenides by H2 O2

The oxidation of organic phenylselenides by H₂ O₂ is investigated in model compounds, namely, n-butyl phenyl selenide (PhSe(nBu)), bis(phenylselanyl)methane (PhSeMeSePh), diphenyl diselenide (PhSeSePh), and 1,2-bis(phenylselanyl)ethane (PhSeEtSePh). Through a combined experimental (¹ H and ⁷⁷ Se NMR) and computational approach, we characterize the direct oxidation of monoselenide to selenoxide, the stepwise double oxidation of PhSeMeSePh that leads to different diastereomeric diselenoxides, the complete oxidation of the diphenyldiselenide that leads to selenium-selenium bond cleavage, and the subsequent formation of the phenylseleninic product. The oxidation of PhSeEtSePh also results in the formation of phenylseleninic acid along with 1-(vinylseleninyl)benzene, which is derived from a side elimination reaction. The evidence of a direct mechanism, in addition to an autocatalytic mechanism that emerges from kinetic studies, is discussed. By considering our observations of diselenides with chalcogen atoms that are separated by alkyl spacers of different length, a rationale for the advantage of diselenide versus monoselenide catalysts is presented.

The potential toxicological insights about the anti-HIV drug azidothymidine-derived monoselenides in human leukocytes: Toxicological insights of new selenium-azidothymidine analogs

Acquired immunodeficiency syndrome (AIDS) is a worldwide disease characterized by impairments of immune function. AIDS can be associated with oxidative stress (OS) that can be linked to selenium (Se) deficiency. Se is fundamental for the synthesis of selenoproteins, such as glutathione peroxidase and thioredoxin reductase. These enzymes catalyze the decomposition of reactive oxygen species and contribute to maintain equilibrium in cell redox status. Literature data indicate that organoselenium compounds, such as ebselen and diphenyl diselenide, have antioxidant properties in vitro and in vivo models associated with OS. Nevertheless, selenocompounds can also react and oxidize thiols groups, inducing toxicity in mammals. Here, we tested the potential cytotoxic and genotoxic properties of six analogs of the prototypal anti-HIV drug azidothymidine (AZT) containing Se (5′-Se-(phenyl)zidovudine; 5′-Se-(1,3,5-trimethylphenyl)zidovudine; 5′-Se-(1-naphtyl)zidovudine; 5′-Se-(4-chlorophenyl)zidovudine) (C4); 5′-Se-(4-methylphenyl)zidovudine (C5); and 5′-(4-methylbenzoselenoate)zidovudine). C5 increased the rate of dithiothreitol oxidation (thiol oxidase activity) and C2-C4 and C6 (at 100 µM) increased DNA damage index (DI) in human leukocytes. Moreover, C5 (200 µM) decreased human leukocyte viability to about 50%. Taken together, these results indicated the low in vitro toxicity in human leukocytes of some Se-containing analogs of AZT.

Hepatic and renal toxicological evaluations of an industrial ovotoxic chemical, 4-vinylcyclohexene diepoxide, in both sexes of Wistar rats

4-Vinylcyclohexene diepoxide (VCD) is an industrial occupational health hazard chemical because it induces ovotoxicity in rodents. The current study investigated the impacts of VCD on selected hepatic and renal markers of oxidative stress and inflammation in both sexes of Wistar rats. Thus, male and female rats were randomly distributed into four groups of ten rats per group, and dosed orally with VCD for 28days. The control male and female groups of rats received corn oil only, while each of the three remaining groups of both sexes of rats received VCD (100, 250 and 500mg/kg BW) respectively. Thereafter, biomarkers of hepatic and renal oxidative damage, inflammation and immunohistochemical expressions of iNOS, COX-2, caspase-9 and caspase-3 were evaluated. The results revealed that VCD increased markers of liver and kidney functions, oxidative damage and inflammation, and disrupted the antioxidant homeostasis of the rats (p<0.05). Lastly, VCD enhanced the immunohistochemical expressions of iNOS, COX-2, caspase-9 and caspase-3 in the liver of the rats. Thus, our data imply that VCD induced toxicity in the liver and kidney of rats via the combined impacts of oxidative damage and inflammation.

Differential genotoxicity of diphenyl diselenide (PhSe)2 and diphenyl ditelluride (PhTe)2

Organoselenium compounds have been pointed out as therapeutic agents. In contrast, the potential therapeutic aspects of tellurides have not yet been demonstrated. The present study evaluated the comparative toxicological effects of diphenyl diselenide (PhSe)₂ and diphenyl ditelluride (PhTe)₂ in mice after in vivo administration. Genotoxicity (as determined by comet assay) and mutagenicicity were used as end-points of toxicity. Subcutaneous administration of high doses of (PhSe)₂ or (PhTe)₂ (500 µmol/kg) caused distinct genotoxicity in mice. (PhSe)₂ significantly decreased the DNA damage index after 48 and 96 h of its injection (p < 0.05). In contrast, (PhTe) caused a significant increase in DNA damage (p < 0.05) after 48 and 96 h of intoxication. (PhSe)₂ did not cause mutagenicity but (PhTe)₂ increased the micronuclei frequency, indicating its mutagenic potential. The present study demonstrated that acute in vivo exposure to ditelluride caused genotoxicity in mice, which may be associated with pro-oxidant effects of diphenyl ditelluride. In addition, the use of this compound and possibly other related tellurides must be carefully controlled.