Substituted diaryl diselenides: cytotoxic and apoptotic effect in human colon adenocarcinoma cells

Synthesis of Thiazolidinedione- and Triazole-Linked Organoselenocyanates and Evaluation of Anticancer Activities Against Breast Cancer with Mechanistic Investigations

Organoselenocyanates are important classes of organoselenium compounds having potential pharmaceutical applications in cancer biology. In the present study, two different series of organoselenocyanates (15 a-15 c and 16 a-16 c) incorporating crucial heterocyclic pharmacophores such as 2,4-thiazolidine-1,3-dione and 1,2,3-triazole were rationally designed. The organoselenocyanates were synthesized using multi-step organic synthesis and investigated for their anticancer activities against triple-negative breast cancer cells. Based on the preliminary anti-proliferative activities and the selectivity index towards cancer cells over the normal cells, 2,4-thiazolidine-1,3-dione-based selenocyanate 15 a was identified as the lead analogue for detailed investigations. In addition to the anti-migratory activity, compound 15 a induced G1-phase arrest of the cell cycle and led to early apoptosis. Further studies on the redox balance of MDA-MB-231 cells indicated the antioxidant nature of 15 a with the quenching of ROS level and upregulation of TrxR1 expression. Detailed mechanistic investigations with the expression levels of key-cancer marker proteins revealed that the selenocyanate 15 a induced the activation of ERK pathway by upregulating p-ERK expression with the subsequent downregulation of p-Akt and c-Myc levels leading to the inhibition of cellular proliferation. Therefore, the primary outcomes of the study would be valuable in the development of chemotherapeutic agents towards the treatment of triple-negative breast cancer.

Diphenyl Diselenide Through Reduction of Inflammation, Oxidative Injury and Caspase-3 Activation Abates Doxorubicin-Induced Neurotoxicity in Rats

Neurotoxicity associated with chemotherapy is a debilitating side effect of cancer management in humans which reportedly involves inflammatory and oxidative stress responses. Diphenyl diselenide (DPDS) is an organoselenium compound which exhibits its anti-tumoral, anti-oxidant, anti-inflammatory and anti-mutagenic effects. Nevertheless, its possible effect on chemotherapy-induced neurotoxicity is not known. Using rat model, we probed the behavioral and biochemical effects accompanying administration of antineoplastic agent doxorubicin (7.5 mg/kg) and DPDS (5 and 10 mg/kg). Anxiogenic-like behavior, motor and locomotor insufficiencies associated with doxorubicin were considerably abated by both DPDS doses with concomitant enhancement in exploratory behavior as demonstrated by reduced heat maps intensity and enhanced track plot densities. Moreover, with exception of cerebral glutathione (GSH) level, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, biochemical data demonstrated reversal of doxorubicin-mediated decline in cerebral and cerebellar antioxidant status indices and the increase in acetylcholinesterase (AChE) activity by both doses of DPDS. Also, cerebellar and cerebral lipid peroxidation, hydrogen peroxide as well as reactive oxygen and nitrogen species levels were considerably diminished in rats administered doxorubicin and DPDS. In addition, DPDS administration abated myeloperoxidase activity, tumour necrosis factor alpha and nitric oxide levels along with caspase-3 activity in doxorubicin-administered rats. Chemoprotection of doxorubicin-associated neurotoxicity by DPDS was further validated by histomorphometry and histochemical staining. Taken together, DPDS through offsetting of oxido-inflammatory stress and caspase-3 activation elicited neuroprotection in doxorubicin-treated rats.

NaOAc-Assisted Aerobic Oxidation Protocol for the Synthesis of Pentacoordinate Chalcogenyl Spirophosphoranes with P-Se/P-S Bonds under Open Air

The NaOAc-assisted aerobic oxidation reaction of pentacoordinate hydrospirophosphoranes and dichalcogenyl compounds with open air as a green oxidant has been developed under mild conditions. A series of novel pentacoordinate spirophosphoranes with P-Se/P-S bonds were synthesized in excellent yields. The reaction mechanism was determined by 31P nuclear magnetic resonance tracing experiments, high-resolution mass spectrometry tracing experiments, and X-ray diffraction analysis. The method features a broad substrate scope, good functional group tolerance, and a high degree of atomic utilization and is meaningful for the synthesis of bioactive chalcogenphosphate compounds with chalcogen and phosphorus moieties.

Antiproliferative Effect of Inorganic and Organic Selenium Compounds in Breast Cell Lines

Triple-negative breast cancer (TNBC) is an aggressive, fast-growing tumor that is more likely to spread to distant organs. Among women diagnosed with breast cancer, the prevalence of TNBC is 20%, and treatment is currently limited to chemotherapy. Selenium (Se), an essential micronutrient, has been explored as an antiproliferative agent. Therefore, this study aimed to evaluate the effects of exposure to organic (selenomethionine, ebselen, and diphenyl diselenide) and inorganic (sodium selenate and sodium selenite) Se molecules in different breast cell lines. The compounds were tested at 1, 10, 50, and 100 μM for 48 h in the non-tumor breast cell line (MCF-10A) and TNBC derivatives cell lines (BT-549 and MDA-MB-231). The effects of Se on cell viability, apoptotic and necrotic processes, colony formation, and cell migration were analyzed. Exposure to selenomethionine and selenate did not alter the evaluated parameters. However, selenomethionine had the highest selectivity index (SI). The exposure to the highest doses of selenite, ebselen, and diphenyl diselenide resulted in antiproliferative and antimetastatic effects. Selenite had a high SI to the BT cell line; however, the SI of ebselen and diphenyl diselenide was low in both tumoral cell lines. In conclusion, the Se compounds had different effects on the breast cell lines, and additional tests are needed to reveal the antiproliferative effects of Se compounds.

Organocatalytic synthesis and antitumor activity of novel 1,2,3-triazoles derived from fatty β-ketoesters

Background:

Developing methods to synthesize highly functionalized and complex 1,2,3-triazoles from various combinations of substrates remains a significant challenge in organic synthesis. Thus, to the best of our knowledge, an organocatalytic approach to synthesize 1,2,3-triazoles derived from fatty acids has not been explored.

Objective:

In this sense, we describe here the organocatalyzed synthesis and preliminary results of antitumor and cytotoxic activity of a range of 1,2,3-triazoles derived from fatty esters.

Methods:

To synthesize 1,2,3-triazoles 3 derived from fatty β-ketoesters, we performed the reaction of appropriate aryl azides 2a-j with β-ketoesters 1a-c in the presence of 5 mol% of DBU using DMSO as a solvent at 70 °C for 24 h. The viability of 5637 cells was determined by measuring the reduction of soluble MTT to water-insoluble formazan. The IC50 concentration that inhibits 50% of cell growth and the results were obtained by at least three independent experiments in triplicate for each test.

Results:

Through enolate-mediated organocatalysis, 1,2,3-triazoles 3 derived from fatty β-ketoesters were synthesized in moderate to excellent yields by reacting fatty esters 1 with aryl azides 2 in the presence of a catalytic amount of 1,8-diazabicyclo[5.4.0]undec-7-ene (5 mol%). All compounds derived from palmitic acetoacetate 1a were evaluated regarding induced cytotoxicity in vitro in a human bladder cancer cell line, and compounds 3a, 3d, 3e, and 3g were shown to be promising alternatives for bladder cancer treatment and presented the lowest inhibitory concentration of IC50.

Conclusion:

We described a synthetic procedure to prepare 1,2,3-triazoles derived from fatty β-ketoesters by DBU-catalyzed 1,3-dipolar cycloaddition reactions of fatty esters with different aryl azides. Compounds derived from palmitic acetoacetate were screened for antitumor and cytotoxic activity in vitro in human bladder cancer cell lines, and compounds 3a, 3d, 3e, and 3g showed potential to treat bladder cancer.

Visible-Light-Induced, Graphene Oxide-Promoted C3-Chalcogenylation of Indoles Strategy under Transition-Metal-Free Conditions

An efficient and general method for the synthesis of 3-sulfenylindoles and 3-selenylindoles employing visible-light irradiation with graphene oxide as a promoter at room temperature has been achieved. The reaction features are high yields, simple operation, metal-free and iodine-free conditions, an easy-to-handle oxidant, and gram-scalable synthesis. This simple protocol allows one to access a wide range of 3-arylthioindoles, 3-arylselenylindoles, and even 3-thiocyanatoindoles with good to excellent yields.

Antimicrobial and cytotoxic capacity of pyroligneous extracts films of Eucalyptus grandis and chitosan for oral applications

Chitosan films containing distilled pyroligneous extracts of Eucalyptus grandis (DPEC), characterized and developed by Brazilian Agricultural Research Corporation-Embrapa Temperate Agriculture (EMBRAPA-CPACT), were evaluated for antimicrobial activity against Candida albicans, Streptococcus mutans, and Lactobacillus acidophilus by direct contact test. Further, their capacity for the prevention of teeth enamel demineralization and cytotoxicity in vitro were also determined. The natural polymers were tested at different concentrations (1500-7500 µg mL-1) and the formulation of an experimental fluoride varnish with antimicrobial activity was evaluated by direct contact test, whereas cytotoxicity was analyzed through the colorimetric MTT assay. Preliminary data showed no statistically significant differences in cytotoxicity to NIH/3T3 cell line when DPEC is compared to the control group. On the other hand, the antimicrobial capacity and demineralization effects were found between the test groups at the different concentrations tested. Chitosan films containing distilled pyroligneous extracts of E. grandis may be an effective control strategy to prevent biofilm formation related to dental caries when applied as a protective varnish. They may inhibit the colonization of oral microorganisms and possibly control dental caries through a decrease in pH and impairment of enamel demineralization.

Small molecule selenium-containing compounds: Recent development and therapeutic applications

Selenium (Se) is an essential micronutrient of organism and has important function. It participates in the functions of selenoprotein in several manners. In recent years, Se has attracted much attention because of its therapeutic potential against several diseases. Many natural and synthetic organic Se-containing compounds were studied and explored for the treatment of cancer and other diseases. Studies have showed that incorporation of Se atom into small molecules significantly enhanced their bioactivities. In this paper, according to different applications and structural characteristics, the research progress and therapeutic application of Se-containing compounds are reviewed, and more than 110 Se-containing compounds were selected as representatives which showed potent activities such as anticancer, antioxidant, antifibrolytic, antiparasitic, antibacterial, antiviral, antifungal and central nervous system related effects. This review is expected to provide a basis for further study of new promising Se-containing compounds.

Selenium Compounds as Novel Potential Anticancer Agents

The high number of new cancer incidences and the associated mortality continue to be alarming, leading to the search for new therapies that would be more effective and less burdensome for patients. As there is evidence that Se compounds can have chemopreventive activity, studies have begun to establish whether these compounds can also affect already existing cancers. This review aims to discuss the different classes of Se-containing compounds, both organic and inorganic, natural and synthetic, and the mechanisms and molecular targets of their anticancer activity. The chemical classes discussed in this paper include inorganic (selenite, selenate) and organic compounds, such as diselenides, selenides, selenoesters, methylseleninic acid, 1,2-benzisoselenazole-3[2H]-one and selenophene-based derivatives, as well as selenoamino acids and Selol.

Design of Pegylated-Nanocapsules to Diphenyl Diselenide Administration: In Vitro Evidence of Hemocompatible and Selective Antiglioma Formulation

Diphenyl diselenide [(PhSe)₂] is a pleiotropic pharmacological agent, but it has low aqueous solubility. The nanoencapsulation of (PhSe)₂ allowed the preparation of an aqueous formulation as well as potentiated its in vitro antitumor effect and the effectiveness in a preclinical model of glioblastoma when administered by the intragastric route. Thus, aiming at maximizing the therapeutic potential of (PhSe)₂, the present study designed a pegylated-formulation intending to intravenous administration of the (PhSe)₂ as a new approach for glioma therapy. The poly(Ɛ-caprolactone) nanocapsules containing (PhSe)₂ were physically coated with polyethyleneglycol (PEG) using the preformed polymer interfacial deposition technique and evaluated through physicochemical, morphological, spectroscopic, and thermal characteristics. Hemocompatibility was determined by the in vitro hemolysis test and cytotoxicity assays were performed in astrocytes and glioma C6 cells (10-100 μM). The pegylated-nanocapsules had an average diameter of 218 ± 25 nm, polydispersity index of 0.164 ± 0.046, zeta potential of - 8.1 ± 1.6 mV, pH 6.0 ± 0.09, (PhSe)₂ content of 102.00 ± 3.57%, and encapsulation efficiency around 98%. Besides, the (PhSe)₂ pegylated-nanocapsules were spherical, presented absence of chemical interaction among the constituents, and showed higher thermal stability than the non-encapsulated materials. PEG-coated nanocapsules did not cause hemolytic effect while formulations without PEG induced a hemolysis rate above 10%. Moreover, pegylated-nanocapsules had superior in vitro antiglioma effect in comparison to free compound (IC₅₀: 24.10 μM and 74.83 μM, respectively). Therefore, the (PhSe)₂-loaded pegylated-nanocapsule suspensions can be considered a hemocompatible formulation for the glioma treatment by the intravenous route.

Selenolesterase enzyme activity of carbonic anhydrases

Carbonic anhydrases (CAs, E.C. 4.2.1.1) are metalloenzymes expressed on a variety of cell types. Their overexpression leads to serious pathologies, including cancer. The discovery of a series of selenolesters with high structural diversity as novel CA inhibitors is reported here. These compounds show remarkable in vitro inhibition against a panel of human CA isoforms such as hCA I, II, IX and XII. We observed that they undergo a CA mediated hydrolysis, releasing different active selenol fragments, which act as CA inhibitors. Notably, to the best of our knowledge, this is the first example of an enzyme with selenolesterase activity. In addition, X-ray crystallographic data support the proposed mechanism, proving selenolesters as novel pro-drug inhibitors with potential pharmacological applications.

Selenium and selenoproteins: it's role in regulation of inflammation

Abstract

Selenium is an essential immunonutrient which holds the human’s metabolic activity with its chemical bonds. The organic forms of selenium naturally present in human body are selenocysteine and selenoproteins. These forms have a unique way of synthesis and translational coding. Selenoproteins act as antioxidant warriors for thyroid regulation, male-fertility enhancement, and anti-inflammatory actions. They also participate indirectly in the mechanism of wound healing as oxidative stress reducers. Glutathione peroxidase (GPX) is the major selenoprotein present in the human body, which assists in the control of excessive production of free radical at the site of inflammation. Other than GPX, other selenoproteins include selenoprotein-S that regulates the inflammatory cytokines and selenoprotein-P that serves as an inducer of homeostasis. Previously, reports were mainly focused on the cellular and molecular mechanism of wound healing with reference to various animal models and cell lines. In this review, the role of selenium and its possible routes in translational decoding of selenocysteine, synthesis of selenoproteins, systemic action of selenoproteins and their indirect assimilation in the process of wound healing are explained in detail. Some of the selenium containing compounds which can acts as cancer preventive and therapeutics are also discussed. These compounds directly or indirectly exhibit antioxidant properties which can sustain the intracellular redox status and these activities protect the healthy cells from reactive oxygen species induced oxidative damage. Although the review covers the importance of selenium/selenoproteins in wound healing process, still some unresolved mystery persists which may be resolved in near future.

Graphic abstract

The direct C3 chalcogenylation of indolines using a graphene-oxide-promoted and visible-light-induced synergistic effect

A green methodology for the construction of carbon–chalcogen (S and Se) bonds via a GO-promoted and metal-free light-induced synergistic effect is demonstrated.

Antitumor action of diphenyl diselenide nanocapsules: In vitro assessments and preclinical evidence in an animal model of glioblastoma multiforme

BACKGROUND

Gliomas are the most aggressive malignant tumors of the central nervous system. The diphenyl diselenide [(PhSe)₂] is an organoselenium compound that has multiple pharmacological properties. Previous reports showed that (PhSe)₂ nanoencapsulation potentiates its in vitro antitumoral action and reduces its toxicity.

OBJECTIVE

In this sense, the current study was designed to further evaluate the (PhSe)₂ antitumoral effect by a set of in vitro techniques using a glioma cell line as well as by an animal model of gliobastoma.

METHODS

For the in vitro tests, the cell viability, propidium iodide uptake and nitrite levels of rat glioma C6 cells were determined after incubation with free (PhSe)₂ or (PhSe)₂-loaded nanocapsules (NC). The glioblastoma model was induced by implantation of C6 glioma cells in the right striatum of rats. Following, animals were submitted to a repeated intragastric administration treatment with (PhSe)₂ or NC (PhSe)₂ (1 mg/kg/day for 15 days) to assess the possible antitumor effect.

MAIN FINDINGS

Both compound forms decreased the C6 glioma cells viability without causing any effect in astrocytes cells (healthy control). Importantly, the NC (PhSe)₂ had superior cytotoxic effect than its free form and increased the nitrite content. Independent of the (PhSe)₂ forms, the intragastric treatment reduced brain tumor size and caused neither alteration in the plasma renal and hepatic markers of function nor in the parameters of oxidative balance in brain, liver and kidneys.

PRINCIPAL CONCLUSIONS

The (PhSe)₂ nanoencapsulation improved its cytotoxic effect against C6 glioma cells and both compound forms attenuated the tumor development.

A Novel Lactate Dehydrogenase Inhibitor, 1-(Phenylseleno)-4-(Trifluoromethyl) Benzene, Suppresses Tumor Growth through Apoptotic Cell Death

The Warburg effect, wherein cancer cells prefer glycolysis rather than oxidative phosphorylation even under normoxic conditions, is a major characteristic of malignant tumors. Lactate dehydrogenase A (LDHA) is the main enzyme regulating the Warburg effect, and is thus, a major target for novel anti-cancer drug development. Through our ongoing screening of novel inhibitors, we found that several selenobenzene compounds have inhibitory effects on LDHA activity. Among them, 1-(phenylseleno)-4-(trifluoromethyl) benzene (PSTMB) had the most potent inhibitory effect on the enzymatic activity of LDHA. The results from biochemical assays and computational modeling showed that PSTMB inhibited LDHA activity. In addition, PSTMB inhibited the growth of several tumor cell lines, including NCI-H460, MCF-7, Hep3B, A375, HT29, and LLC. In HT29 human colon cancer cells, PSTMB dose-dependently inhibited the viability of the cells and activity of LDHA, without affecting the expression of LDHA. Under both normoxic and hypoxic conditions, PSTMB effectively reduced LDHA activity and lactate production. Furthermore, PSTMB induced mitochondria-mediated apoptosis of HT29 cells via production of reactive oxygen species. These results suggest that PSTMB may be a novel candidate for development of anti-cancer drugs by targeting cancer metabolism.

Revitalizing the AZT Through of the Selenium: An Approach in Human Triple Negative Breast Cancer Cell Line

Triple-negative breast cancer represents about 15% of all cases of breast cancer, and still represents a therapeutic challenge. 3′-Azido-3′-deoxythymidine (AZT) is a nucleoside reverse transcriptase inhibitor with antitumor activity. Chalcogenides compounds, such as selenium, are very important intermediates applied in organic synthesis. Our objective was to investigate the effect and the underlying cell death mechanisms of AZT and its derivatives, in human breast cancer cell lines. The inhibitory effect of AZT and derivatives (1072, 1073, and 1079) was determined by MTT assay (0.1, 1, 10, 50, and 100 μM for concentrations and times 4, 24, 48, and 72 h) and Live/Dead in tumor cell lines MCF-7, MDA-MB 231 and also in non-tumor cell line CHO. Gene expression profiles related to apoptosis were investigated by qRT-PCR and induction of apoptosis was investigated by flow cytometry. MTT and Live/Dead assays showed that AZT derivatives decreased the rate of cell proliferation at concentrations of 50 and 100 μM in tumor cell lines MCF-7 and MDA-MB 231 while the commercial AZT presented a low antitumoral potential in all strains tested. In flow cytometry analysis we demonstrated that derivatives of AZT induced apoptosis, with an increase in both initial and late stages in both tumor cell lines evaluated, especially in MDA-MB 231. Our data show that the AZT derivative 1072 increased the expression of transcripts of the genes caspase 3 and 8 in MDA-MB 231 cell line when compared to control, suggesting that the extrinsic pathway of apoptosis was activated. In conclusion, derivatives of AZT, especially 1072, induce cytotoxicity in vitro in the triple negative breast cancer cell line through activation of the extrinsic pathway of apoptosis. These compounds containing selenium in its formulation are potential therapeutic agents for breast cancer.

Organic selenium compounds as potential chemotherapeutic agents for improved cancer treatment

Selenium(Se)-containing compounds have attracted a growing interest as anticancer agents over recent decades, with mounting reports demonstrating their high efficacy and selectivity against cancer cells. Typically, Se compounds exert their cytotoxic effects by acting as pro-oxidants that alter cellular redox homeostasis. However, the precise intracellular targets, signalling pathways affected and mechanisms of cell death engaged following treatment vary with the chemical properties of the selenocompound and its metabolites, as well as the cancer model that is used. Naturally occurring organic Se compounds, besides encompassing a significant antitumor activity with an apparent ability to prevent metastasis, also seem to have fewer side effects and less systemic effects as reported for many inorganic Se compounds. On this basis, many novel organoselenium compounds have also been synthesized and examined as potential chemotherapeutic agents. This review aims to summarize the most well studied natural and synthetic organoselenium compounds and provide the most recent developments in our understanding of the molecular mechanisms that underlie their potential anticancer effects.

Selenides and Diselenides: A Review of Their Anticancer and Chemopreventive Activity

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.

Melatonin delivery by nanocapsules during in vitro bovine oocyte maturation decreased the reactive oxygen species of oocytes and embryos

In this work, a promising approach to increase the advantageous properties of melatonin through its encapsulation into lipid-core nanocapsules (LNC) was examined. Oocytes were treated during in vitro maturation with non-encapsulated melatonin (Mel), melatonin-loaded lipid-core nanocapsules (Mel-LNC), and unloaded LNC. Cytotoxicity, meiotic maturation rate, development to the blastocyst stage, reactive oxygen species (ROS) and glutathione levels, mean cell number and apoptotic cell/blastocyst, and mRNA quantification were evaluated. Both Mel and Mel-LNC enhanced in vitro embryo production, however, Mel-LNC proved to be more effective at decreasing ROS levels and the apoptotic cell number/blastocyst, increasing the cleavage and blastocyst rates, up-regulating the GPX1 and SOD2 genes, and down-regulating the CASP3 and BAX genes. Mel-LNC could penetrate into oocytes and remain inside the cells until they reach the blastocyst stage. In conclusion, when melatonin was encapsulated in LNC and applied during in vitro oocyte maturation, some quality aspects of the blastocysts were improved.

(7-Chloroquinolin-4-yl)arylhydrazones: Candida albicans enzymatic repression and cytotoxicity evaluation, Part 2

OBJECTIVE

This work describes the anti-enzymatic activity of (7-chloroquinolin-4-yl)arylhydrazones against Candida albicans and examines their cytotoxicity.

MATERIAL AND METHODS

Ten C. albicans strains [nine isolates and one azole-resistant standard strain (ATCC 62342)] were used to assess the anti-enzymatic activity. Fifteen compounds at sub-antifungal concentrations ranging from 12.5 to 100 µg/ml were assessed after a 30-min exposure. The strains were seeded onto petri dishes with selective agar media for aspartyl proteases (Saps) and phospholipases (PLs). Enzymatic inhibition was measured by the reduction of the precipitation zone (Pz) against untreated strains (positive control). A colorimetric MTT assay was used with 3T3/NIH mouse fibroblasts to evaluate cytotoxicity. Cells were exposed to 15 compounds in concentrations from 6.25 to 100 µg/ml for 24 and 48 h.

RESULTS

Four hydrazones showed enzymatic repression values over 40% to Pl and three over 20% to Saps. The cell viability was over 50% at hydrazone concentrations of 25-100 µg/ml.

CONCLUSION

These results revealed that select (7-chloroquinolin-4-yl)arylhydrazones may be potential antifungal agents for the control of C. albicans infections.

In vitro radical scavenging and cytotoxic activities of novel hybrid selenocarbamates

Novel selenocyanate and diselenide derivatives containing a carbamate moiety were synthesised and evaluated in vitro to determine their cytotoxic and radical scavenging properties. Cytotoxic activity was tested against a panel of human cell lines including CCRF-CEM (lymphoblastic leukaemia), HT-29 (colon carcinoma), HTB-54 (lung carcinoma), PC-3 (prostate carcinoma), MCF-7 (breast adenocarcinoma), 184B5 (non-malignant, mammary gland derived) and BEAS-2B (non-malignant, derived from bronchial epithelium). Most of the compounds displayed high antiproliferative activity with GI50 values below 10μM in MCF-7, CCRF-CEM and PC-3 cells. Radical scavenging properties of the new selenocompounds were confirmed testing their ability to scavenge DPPH and ABTS radicals. Based on the activity of selenium-based glutathione peroxidases (GPxs), compounds 1a, 2e and 2h were further screened for their capacity to reduce hydrogen peroxide under thiol presence. Results suggest that compound 1a mimics GPxs activity. Cytotoxic parameters, radical scavenging activity and ADME profile point to 1a as promising drug candidate.

Brazilian red propolis induces apoptosis-like cell death and decreases migration potential in bladder cancer cells

Natural products continue to be an invaluable resource of anticancer drug discovery in recent years. Propolis is known for its biological activities such as antimicrobial and antitumor effects. This study assessed the effects of Brazilian red propolis (BRP) on apoptosis and migration potential in human bladder cancer cells. The effect of BRP ethanolic extract (25, 50, and 100 μg/mL) on 5637 cells was determined by MTT, LIVE/DEAD, and migration (scratch assay) assays. Apoptosis induction was investigated through flow cytometry and gene expression profile was investigated by qRT-PCR. Results showed cytotoxicity on MTT and LIVE/DEAD assays, with IC₅₀ values of 95 μg/mL in 24 h of treatment. Cellular migration of 5637 cells was significantly inhibited through lower doses of BRP ethanolic extract (25 and 50 μg/mL). Flow cytometry analyses showed that BRP induced cytotoxicity through apoptosis-like mechanisms in 5637 cells and qRT-PCR revealed increased levels of Bax/Bcl-2 ratio, p53, AIF, and antioxidant enzymes genes. Data suggest that BRP may be a potential source of drugs to bladder cancer treatment.

Selenium compounds as therapeutic agents in cancer

BACKGROUND

With cancer cells encompassing consistently higher production of reactive oxygen species (ROS) and with an induced antioxidant defense to counteract the increased basal ROS production, tumors have a limited reserve capacity resulting in an increased vulnerability of some cancer cells to ROS. Based on this, oxidative stress has been recognized as a tumor-specific target for the rational design of new anticancer agents. Among redox modulating compounds, selenium compounds have gained substantial attention due to their promising chemotherapeutic potential.

SCOPE OF REVIEW

This review aims in summarizing and providing the recent developments of our understanding of the molecular mechanisms that underlie the potential anticancer effects of selenium compounds.

MAJOR CONCLUSIONS

It is well established that selenium at higher doses readily can turn into a prooxidant and thereby exert its potential anticancer properties. However, the biological activity of selenium compounds and the mechanism behind these effects are highly dependent on its speciation and the specific metabolic pathways of cells and tissues. Conversely, the chemical properties and the main molecular mechanisms of the most relevant inorganic and organic selenium compounds as well as selenium-based nanoparticles must be taken into account and are discussed herein.

GENERAL SIGNIFICANCE

Elucidating and deepening our mechanistic knowledge of selenium compounds will help in designing and optimizing compounds with more specific antitumor properties for possible future application of selenium compounds in the treatment of cancer. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.

Synthesis of new diorganodiselenides from organic halides: their antiproliferative effects against human breast cancer MCF-7 cells

A new series of bis(aryl or aralkyl) diselenides 5a-5q was synthesized by selenylation from aryl halide (or aralkyl halide) for development of new anticancer agents. The process involves the reaction of aryl halides (or aralkyl halides) with selenium, hydrazine hydrate under atmospheric pressure in the presence of sodium hydroxide, to afford diorganodiselenides. These new compounds showed antiproliferative activities against breast cancer (MCF-7) cells in CCK-8 assays, and could be promising candidates for chemotherapy of carcinomas. Among 17 synthesized compounds for inhibiting the growth of these cell lines, 1,2-bis(chloropyridazinyl) diselenide 5a showed the highest potency. This result suggests the potential anticancer activity of compound 5a.

Antifungal susceptibility, exoenzyme production and cytotoxicity of novel oximes against Candida

Novel oximes were synthesized, their in vitro antifungal activity against Candida was evaluated and their cytotoxicity was determined. The procedure used for the synthesis of the oximes is aligned with the current green chemistry trend; water is employed as the solvent in this reaction. The minimum inhibitory and minimum fungicidal concentrations of the oximes were evaluated using the CLSI M27-A3 method. The influence of these compounds on the inhibition of the production of hydrolytic enzymes, phospholipase and proteinase by Candida was also investigated. The compounds showed a good ability to inhibit phospholipase, with a 50 % reduction in most cases. However, the tested compounds did not affect proteinase. The current results showed a substantial reduction in the phospholipase production, which suggests that compounds of this class may interfere with host infection and disease progression. The oximes examined showed lower fungicidal activities than fluconazole but interfered significantly with the expression of phospholipase. Some of the oximes included in this study could be a suitable matrix for the development of novel antifungal compounds.