© 2021 Elsevier B.V.Sprouts enriched with selenium offer increased nutritional value and chemopreventive properties raising interest in their contribution to the human diet. The effect of selenium depends on its concentration and the chemical forms. The aims of this study were: to synthesize several novel organic selenium compounds (selenoesters), to examine how effectively they can deliver selenium to Brassica sprouts, and investigate their metabolism in sprouts. We revealed that selenium content in the fortified sprouts was several orders of magnitude higher than in the unfortified ones. There were significant differences between doses of selenium delivered to sprouts by different selenium compounds. A small percentage of supplemented selenium (<10%) was incorporated into the sprouts as seleno-L-methionine, Se(IV) and Se-methylselenocysteine, while several other low molecular weight selenium species were also identified, in different proportions, depending on the compound used in the fortification procedure. In conclusion: novel selenorganic compounds were successfully applied to fortify kale sprouts in selenium. The detection, screening, and characterization (including structure elucidation) of their low molecular weight metabolites and derivatives have previously been unreported in Brassica genus.

A series of 17 arylpiperazine derivatives of the 5-spiroimidazolidine-2,4-diones (6–22) has been explored, including variations in (i) the number of aromatic rings at position 5, (ii) the length of the linker, as well as (iii) the kind and position of the linked arylpiperazine terminal fragment. Synthesis (6–16) and X-ray crystallographic studies for representative compounds (8, 10, 14 and 18) have been performed. The ability to inhibit the tumor multidrug resistance (MDR) efflux pump P-glycoprotein (P-gp, ABCB1) overexpressed in mouse T-lymphoma cells was investigated. The cytotoxic and antiproliferative actions of the compounds on both the reference and the ABCB1-overproducing cells were also examined. The pharmacophore-based molecular modeling studies have been performed. ADMET properties in vitro of selected most active derivatives (6, 11 and 12) have been determined. All compounds, excluding 18, inhibited the cancer P-gp efflux pump with higher potency than that of reference verapamil. The spirofluorene derivatives with amine alkyl substituents at position 1, and the methyl group at position 3 (6–16), occurred the most potent P-gp inhibitors in the MDR T–lymphoma cell line. In particular, compounds 7 and 12 were 100-fold more potent than verapamil. Crystallography-supported pharmacophore-based SAR analysis has postulated specific structural properties that could explain this excellent cancer MDR-inhibitory action. © 2021 Elsevier Inc.

© 2021 Elsevier LtdAn exhaustive review on the application of different metal-based nanoparticles for the upgrading of heavy oils has been performed. Particular emphasis has been put on those catalysts used for in-situ upgrading using various thermal treatment methods aiming at extracting heavy oils in a more effective manner. Different types of catalysts have been identified, such as monometallic (Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ce, and W), non-supported bimetallic (Ti/Zr), non-supported polymetallic (various mixtures of Co, Mo, Ni, W, Al, Zn, Cu), and supported (various metals on silica, alumina, carbon, zeolite, biogenic particles, complex inorganic and organic). Due to the great diversity of nanoparticulated catalysts (type, metal content, synthesis procedure, particle size) and evaluation conditions (experimental setup, reaction conditions, type of feed), it is not possible to make a direct comparison on their performance. Some results are highlighted on the effectiveness of the catalysts for heavy oil upgrading in terms of asphaltene adsorption, viscosity reduction, increase of API gravity, and coke formation. The reviewed literature indicates the need for more research on this topic as to develop more effective catalysts not only for increasing the recovery factor but also for permanent upgrading of the quality of heavy and extra-heavy oil.

Fifteen selenocompounds, comprising of eight ketone-containing selenoesters (K1–K8, also known as oxoselenoesters) and seven cyano-containing selenoesters (N1–N7, known also as cyanoselenoesters), have been designed, synthesized, and evaluated as novel anticancer agents. These compounds are derivatives of previously reported active selenoesters and were prepared following a three-step one-pot synthetic route. The following evaluations were performed in their biological assessment: cytotoxicity determination, selectivity towards cancer cells in respect to non-cancer cells, checkerboard combination assay, ABCB1 inhibition and inhibition of ABCB1 ATPase activity, apoptosis induction, and wound healing assay. As key results, all the compounds showed cytotoxicity against cancer cells at low micromolar concentrations, with cyanoselenoesters being strongly selective. All of the oxoselenoesters, except K4, were potent ABCB1 inhibitors, and two of them, namely K5 and K6, enhanced the activity of doxorubicin in a synergistic manner. The majority of these ketone derivatives modulated the ATPase activity, showed wound healing activity, and induced apoptosis, with K3 being the most potent, with a potency close to that of the reference compound. To summarize, these novel derivatives have promising multi-target activity, and are worthy to be studied more in-depth in future works to gain a greater understanding of their potential applications against cancer. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Infections caused by Salmonella species and Staphylococcus aureus represent major health and food industry problems. Bacteria have developed many strategies to resist the antibacterial activity of antibiotics, leading to multidrug resistance (MDR). The over-expression of drug efflux pumps and the formation of biofilms based on quorum sensing (QS) can contribute the emergence of MDR. For this reason, the development of novel effective compounds to overcome resistance is urgently needed. This study focused on the antibacterial activity of nine symmetrical selenoesters (Se-esters) containing additional functional groups including oxygen esters, ketones, and nitriles against Gram-positive and Gram-negative bacteria. Firstly, the minimum inhibitory concentrations of the compounds were determined. Secondly, the interaction of compounds with reference antibiotics was examined. The efflux pump (EP) inhibitory properties of the compounds were assessed using real-time fluorimetry. Finally, the anti-biofilm and quorum sensing inhibiting effects of selenocompounds were determined. The methylketone and methyloxycarbonyl selenoesters were the more effective antibacterials compared to cyano selenoesters. The methyloxycarbonyl selenoesters (Se-E2 and Se-E3) showed significant biofilm and efflux pump inhibition, and a methyloxycarbonyl selenoester (Se-E1) exerted strong QS inhibiting effect. Based on results selenoesters could be promising compounds to overcome bacterial MDR. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Multidrug resistance of cancer cells to cytotoxic drugs still remains a major obstacle to the success of chemotherapy in cancer treatment. The development of new drug candidates which may serve as P-glycoprotein (P-gp) efflux pump inhibitors is a promising strategy. Selenium analogues of natural products, such as flavonoids, offer an interesting motif from the perspective of drug design. Herein, we report the biological evaluation of novel hybrid compounds, bearing both the flavone core (compounds 1–3) or a bioisosteric analogue core (compounds 4–6) and the triflyl functional group against Gram-positive and Gram-negative bacteria, yeasts, nematodes, and human colonic adenocarcinoma cells. Results show that these flavones and analogues of flavones inhibited the activity of multidrug resistance (MDR) efflux pump ABCB1 (P-glycoprotein, P-gp). Moreover, the results of the rhodamine 123 accumulation assay demonstrated a dose-dependent inhibition of the abovementioned efflux pump. Three compounds (4, 5, and 6) exhibited potent inhibitory activity, much stronger than the positive control, verapamil. Thus, these chalcogen bioisosteric analogues of flavones become an interesting class of compounds which could be considered as P-gp efflux pump inhibitors in the therapy of MDR cancer. Moreover, all the compounds served as promising adjuvants in the cancer treatment, since they exhibited the P-gp efflux pump modulating activity. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

The emergence of drug‐resistant pathogens leads to a gradual decline in the efficacy of many antibacterial agents, which poses a serious problem for proper therapy. Multidrug resistance (MDR) mechanisms allow resistant bacteria to have limited uptake of drugs, modification of their target molecules, drug inactivation, or release of the drug into the extracellular space by efflux pumps (EPs). In previous studies, selenoesters have proved to be promising derivatives with a noteworthy antimicrobial activity. On the basis of these results, two series of novel selenoesters were synthesized to achieve more potent antibacterial activity on Gram‐positive and Gram‐negative bacteria. Fifteen selenoesters (eight ketone‐selenoesters and seven cyano‐selenoesters) were investigated with regards to their efflux pump‐inhibiting, anti‐quorum‐sensing (QS), and antibiofilm effects in vitro. According to the results of the antibacterial activity, the ketone‐selenoesters proved to be more potent antibacterial compounds than the cyano‐selenoesters. With regard to efflux pump inhibition, one cyano‐selenoester on methicillin‐resistant S. aureus and one ketoneselenoester on Salmonella Typhimurium were potent inhibitors. The biofilm inhibitory capacity and the ability of the derivatives to disrupt mature biofilms were noteworthy in all the experimental systems applied. Regarding QS inhibition, four ketone‐selenoesters and three cyano‐selenoesters exerted a noteworthy effect on Vibrio campbellii strains. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

A series of 33 novel (thio)urea-containing compounds were initially designed and synthesized as potential ligands for the histamine H4 receptor (H4R). However, only 3 compounds showed a statistically significant affinity towards H4R (Ki<10 μM). Considering the structural analogy of these thioureas to previously described seleno/thiourea compounds with anticancer and/or reversal multidrug resistance action in cancer cells, selected thioureas were evaluated in in vitro cytotoxicity- and cancer multidrug resistance assays. The thiourea derivatives showed a good cytotoxic activity, being the compound 13 d (4-methyl-N-(p-phenylphenyl)-piperazine-1-carbothiamide) the most active (IC50= 11.9 μM). They also enhanced the cytotoxicity of the topoisomerase inhibitors topotecan and doxorubicin in a checkerboard combination assay. Compound 13 d showed the strongest synergistic effect on topotecan activity, whereas 13 c (4-methyl-N-(p-tolyl)-piperazine-1-carbothiamide) was the best in combination with doxorubicin. These results can be a good starting point to design more potent and effective (thio)urea derivatives with anticancer activity. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Background/Aim: Selenium-containing compounds are becoming new alternatives in experimental chemotherapy in order to overcome multidrug resistance in cancer. The main goal of this study was to determine whether combined treatment with new Se-compounds would increase the effect of conventional doxorubicin chemotherapy in breast cancer cell lines. Materials and Methods: Se-compounds were evaluated regarding their cytotoxic and apoptosis-inducing effect on MCF-7 and ATP-binding cassette subfamily B member 1 (ABCB1)-overexpressing KCR breast cancer cell lines. Moreover, the interaction of Se-compounds with doxorubicin was assessed using the MTT assay. Results: Selenoanhydride exerted a selective activity towards the doxorubicin-resistant KCR cell line overexpressing ABCB1. Among the selenoesters, only ketone-containing selenoesters exerted significant cytotoxic activity against MCF-7 and KCR cell lines and the Se-compounds acted synergistically with doxorubicin on the KCR cell line. Conclusion: The importance of the COSeCH2COCH3 and COSeCH2CO(CH3)3 moieties for the cytotoxic and adjuvant role of Se-compounds was highlighted. © 2019 International Institute of Anticancer Research. All rights reserved.

In this study, the hydrothermal upgrading (HTU) of high sulfur-content heavy oil was investigated at sub-critical (Sub-CW), near-critical (NCW) and supercritical water (SCW) conditions. Products obtained after HTU, including gases, liquid, and coke (if formed), were analyzed to understand the upgrading performance at different conditions. At Sub-CW (200, 250, and 300 °C), 250 °C is the optimum temperature where a viscosity reduction from 2073 to 1758 mPa s was achieved with a slight removal of sulfur (mainly sulfur) and the generation of a small amount of light and non-condensable hydrocarbons in gas phase (C1–C4, isoalkanes and alkenes, H2S, CO2 and H2, etc.). At NCW (350 °C) and SCW (400 °C), heavy oil was upgraded into light oil with a significant removal of heteroatoms, an increase of saturates content, a reduction of aromatics, resins and asphaltenes contents, and a high yield of light gaseous hydrocarbons (mainly methane). Simultaneously, each SARA fraction was also greatly ameliorated: the content of light alkanes with low molecular weight in saturates was increased, diaromatics content in aromatics was increased with a reduction of polyaromatics content, aromatics-type carbon atoms in resins was increased with a decrease in aliphatic hydrocarbons. Moreover, MALDI-TOF measurements of asphaltenes show that the molecular weights of asphaltenes were reduced. All these results indicated that HTU at Sub-CW can be used for heavy oil pre-treatment (in-situ or ex-situ upgrading) considering its main effect of viscosity reduction with a small removal of heteroatoms, while HTU at NCW and SWC has a great potential in in-situ and ex-situ upgrading and oil refining as it can convert heavy oil into light oil. © 2019 Elsevier B.V.

Malignant diseases present a serious public health burden and their treatment with traditional chemotherapy cannot be considered an all-round solution, due to toxic side effects. Selenium compounds (Se-compounds) have received substantial attention in medicinal chemistry, especially in experimental chemotherapy, both as cytotoxic agents and adjuvants in chemotherapy. A checkerboard microplate method was applied to study the drug interactions of Se-compounds and clinically relevant chemotherapeutic drugs against the multidrug-resistant (MDR) subtype of mouse T-lymphoma cells overexpressing the ABCB1 transporter. Se-compounds showed synergistic interactions with chemotherapeutic agents targeting the topoisomerase enzymes or the microtubule apparatus. The ketone-containing selenoesters showed synergism at lower concentrations (1.25 µM). Most of the tested compounds interacted antagonistically with alkylating agents and verapamil. A thiophene-containing Se-compound showed synergism with all tested drugs, except cisplatin. While the exact mechanism of drug interactions is yet unknown, the potency of the selenocompounds as efflux pump inhibitors or the potentiation of their efficacy as reactive oxygen species modulators may play a role in their complementary activity against the tested MDR lymphoma cell line. © 2019 by the authors.

Bacterial multidrug resistance is becoming a growing problem for public health, due to the development and spreading of bacterial strains resistant to antimicrobials. In this study, the antibacterial and multidrug resistance reversing activity of a series of seleno-carbonyl compounds has been evaluated. The effects of eleven selenocompounds on bacterial growth were evaluated in Staphylococcus aureus, methicillin resistant S. aureus (MRSA), Enterococcus faecalis, Escherichia coli, and Chlamydia trachomatis D. The combination effect of compounds with antibiotics was examined by the minimum inhibitory concentration reduction assay. Their efflux pump (EP) inhibitory properties were assessed using real-time fluorimetry. Relative expressions of EP and quorum-sensing genes were studied by quantitative PCR. Results showed that a methylketone selenoester had remarkable antibacterial activity against Gram-positive bacteria and potentiated the activity of oxacillin in MRSA. Most of the selenocompounds showed significant anti-chlamydial effects. The selenoanhydride and the diselenodiester were active inhibitors of the AcrAB-TolC system. Based on these results it can be concluded that this group of selenocompounds can be attractive potential antibacterials and EP inhibitors. The discovery of new derivatives with a significant antibacterial activity as novel selenocompounds, is of high impact in the fight against resistant pathogens. © 2019 by the authors.

Polysulfides (H2Sx) represent a class of reactive sulfur species (RSS) which includes molecules such as H2S2, H2S3, H2S4, and H2S5, and whose presence and impact in biological systems, when compared to other sulfur compounds, has only recently attracted the wider attention of researchers. Studies in this field have revealed a facet-rich chemistry and biological activity associated with such chemically simple, still unusual inorganic molecules. Despite their chemical simplicity, these inorganic species, as reductants and oxidants, metal binders, surfactant-like 'cork screws' for membranes, components of perthiol signalling and reservoirs for inorganic hydrogen sulfide (H2S), are at the centre of complicated formation and transformation pathways which affect numerous cellular processes. Starting from their chemistry, the hidden presence and various roles of polysulfides in biology may become more apparent, despite their lack of clear analytical fingerprints and often murky biochemical footprints. Indeed, the biological chemistry of H2Sx follows many unexplored paths and today, the relationship between H2S and its oxidized H2Sx species needs to be clarified as a matter of 'unmistaken identity'. Simultaneously, emerging species, such as HSSeSH and SenS8-n, also need to be considered in earnest. © 2019 by the authors.

Metabolic stability, mutagenicity, antimutagenicity, and the ability to scavenge free radicals of four novel 8-methoxy-purine-2,6-dione derivatives (compounds 1–4) demonstrating analgesic and anti-inflammatory properties were determined. Metabolic stability was evaluated in Cunninghamella and microsomal models, mutagenic and antimutagenic properties were assessed using the Ames and the Vibrio harveyi tests, and free radical scavenging activity was evaluated with 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. In the Cunninghamella model, compound 2 did not undergo any biotransformation; whereas 3 and 4 showed less metabolic stability: 1–9 and 53–88\% of the parental compound, respectively, underwent biotransformation reactions in different Cunninghamella strains. The metabolites detected after the biotransformation of 3 and 4 were aromatic hydroxylation and N-dealkylation products. On the other hand, the N-dealkylation product was the only metabolite formed in microsome assay. Additionally, these derivatives do not possess mutagenic potential in microbiological models (Vibrio harveyi and Salmonella typhimurium) considered. Moreover, all compounds showed a strong chemopreventive activity in the modified Vibrio harveyi strains BB7X and BB7M. However, radical scavenging activity was not the mechanism which explained the observed chemopreventive activity. © 2017, The Author(s).

Purpose of the Review: The aim of this work is to review systematically the selenocyanate-containing compounds reported so far with potential applications in cancer prevention and in cancer treatment, attempting to focus on the most active selenocyanate derivatives. Recent Findings: The chemopreventive and anticancer activity of selenocyanate-containing compounds as p-xylene selenocyanate and benzyl selenocyanate was found long time ago and has been deeply studied, revealing that this functional group can affect to very different cellular and metabolic targets. In the last years, novel active compounds that combine the selenocyanate moiety with different heterocycles, quinones, or steroids have been reported, renewing the interest in this selenium-containing functional group and discovering compounds with promising properties. Generally, these compounds show antiproliferative or cytotoxic activity, although certain ones are potent antioxidant agents. The novel heterocyclic compounds are mostly substituted with a –CH2SeCN moiety but longer aliphatic linkers between the ring core and the –SeCN group can be also found. Isatins, quinazolines, oxadiazoles, pyrimidinones, and tacrines can be highlighted among the heterocycles found in novel active compounds, whereas certain derivatives of diosgenin and cholestane are active steroid-containing selenocyanates. Summary: Selenocyanates are a promising class of selenocompounds that generally show interesting properties as chemopreventive or as anticancer agents. © 2018, Springer Nature Switzerland AG.

Selenium and selenocompounds have attracted the attention and the efforts of scientists worldwide due to their promising potential applications in cancer prevention and/or treatment. Different organic selenocompounds, with diverse functional groups that contain selenium, have been reported to exhibit anticancer and/or chemopreventive activity. Among them, selenocyanates, selenoureas, selenoesters, selenium-containing heterocycles, selenium nanoparticles, selenides and diselenides have been considered in the search for efficiency in prevention and treatment of cancer and other related diseases. In this review, we focus our attention on the potential applications of selenides and diselenides in cancer prevention and treatment that have been reported so far. The around 80 selenides and diselenides selected herein as representative compounds include promising antioxidant, prooxidant, redox-modulating, chemopreventive, anticancer, cytotoxic and radioprotective compounds, among other activities. The aim of this work is to highlight the possibilities that these novel organic selenocompounds can offer in an effort to contribute to inspire medicinal chemists in their search of new promising derivatives. © 2018 by the authors.

Aim and Objective: Selenium (Se) compounds are often associated with good reactivity and selectivity due to specific modifications of thiol groups in peptides, proteins and enzymes. Among them, selenazolinium salts are of particular interest, as they react readily with their thiol targets. This study was undertaken to verify whether this reactivity translates into biological activity against a few selected organisms. Materials and Methods: To screen the activity of selenazolinium salts, we performed nematicidal activity assay using Steinernema feltiae. To determine their impact on microbial proliferation, viability of Escherichia coli and Saccharomyces cerevisiae cells was monitored. For a chemical genetic phenotyping focused on a redox link, 32 redox-related S. cerevisiae mutants were used. DNA double-strand breakage caused by selenazolinium salts was investigated using pulsed-field gel electrophoresis and their physico-chemical properties were assessed using nuclear magnetic resonance (NMR). Results: Some of selenazolinium salts are toxic against S. feltiae at a concentration of 100-500 μM. In E. coli, selenazolium salts display no toxicity at a concentration of 100 μM; however, at a concentration of 500 μM some of them show a statistically relevant toxicity. Similar findings were obtained in wild-type S. cerevisiae cells. Only a few redox-related mutants show higher sensitivity to selenazolinium salts compared to wild-type cells. Selenazolinium salts induce DNA double-strand breaks at moderate doses (10-100 μM).77 Se-NMR shifts reflect some of the trends observed in the biological assays. Conclusion: Our results confirmed that several of selenazolinium salts show a significant biological activity that is executed via an electrophilic attack. © 2017 Bentham Science Publishers.

In the present work, three flavonoids (Fls) namely, quercetin (quer), morin (mor), and primuletin (prim) as well as their metal; (Cu(II) and Fe(III)) complexes (M-Fls) were deposited on APTES-FTO ((3-aminopropyl)triethoxysilane-fluorine doped tin oxide) electrodes. The formation of the (M-)Fls-APTES-FTO surface was verified and characterized through AT-FTIR. These surfaces were found to detect the OH radical at a concentration as low as 2 nM using cyclic and square wave voltammetry and the decrease in the anodic peak currents of (M-)Fls-APTES-FTO working electrodes could be taken as a measure of the OH[rad] radical concentration in the sample. Furthermore, a comparison of the decrease in the peak currents of (M-)Fls-APTES-FTO caused by OH[rad] to the decrease noted in the presence of 100-fold higher concentrations of other reactive oxygen species (ROS including superoxide anion, alkylperoxide anion, singlet oxygen, chlorine monoxide, and hydrogen peroxide), confirmed a high selectivity and rather insignificant interference by other ROS of no more than 4\%. Thus, this method provides significant selectivity in the electrochemical detection of the OH[rad] radical. Among the (M-)Fls tested for hydroxyl radical detection, the most sensitive ones were Fe-quer, Cu-quer and Fe-mor deposited on APTES-FTO. © 2017 Elsevier Ltd