Azaanalogues of ebselen as antimicrobial and antiviral agents: synthesis and properties

N-heterocyclic carbene based Bi-nuclear organoselenium compounds impart a mild biocidal potential compared to their ligands: Synthesis, characterization, computational studies

N-heterocyclic carbene (NHC) based compounds are remarkably known for astonishing biological potentials. Coordination of metal center with these compounds can substantially improve the biological potential for better efficacy. In this context, three binuclear azolium salts (L1-L3) and subsequent selenium adducts L1Se-L3Se were synthesized and assured through analytical techniques. Synthesized compounds were also simulated through computational approach and results were compared with experimental observations that also relatable with biological potentials. Synthesized compounds were screened against bacterial strains and interestingly, the studied compounds showed good antimicrobial potential with MIC values of 7.01, 10.7 and 10.5 µM for S. Aureus (gram positive bacteria) while 12.5, 11.75 and 14.5 µM against E. Coli (gram negative bacteria). The studied compounds showed good antioxidant activity to scavenge DPPH free radicals among which azolium salts were found better in antioxidant potential (IC50 5.75-6.55 µg/mL) than their respective selenium compounds (IC50 9.50-12.75 µg/mL). The hemolytic assay against red blood cells showed that ligands are least toxic comparative to their Se-adducts and can be further trialed for In Vivo studies.

Antimicrobial Coatings for Medical Textiles via Reactive Organo-Selenium Compounds

Bleached and cationized cotton fabrics were chemically modified with reactive organoselenium compounds through the nucleophilic aromatic substitution (SNAr) reaction, which allowed for organo-selenium attachment onto the surface of cotton fabrics via covalent bonds and, in the case of the cationized cotton fabric, additional ionic interactions. The resulting textiles exhibited potent bactericidal activity against S. aureus (99.99% reduction), although only moderate activity was observed against E. coli. Fabrics treated with reactive organo-selenium compounds also exhibited fungicidal activities against C. albicans, and much higher antifungal activity was observed when organo-selenium compounds were applied to the cationized cotton in comparison to the bleached cotton. The treatment was found to be durable against rigorous washing conditions (non-ionic detergent/100 °C). This paper is the first report on a novel approach integrating the reaction of cotton fabrics with an organo-selenium antimicrobial agent. This approach is attractive because it provides a method for imparting antimicrobial properties to cotton fabrics which does not disrupt the traditional production processes of a textile mill.

Exploring nanoselenium to tackle mutated SARS-CoV-2 for efficient COVID-19 management

Despite ongoing public health measures and increasing vaccination rates, deaths and disease severity caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its new emergent variants continue to threaten the health of people around the world. Therefore, there is an urgent need to develop novel strategies for research, diagnosis, treatment, and government policies to combat the variant strains of SARS-CoV-2. Since the state-of-the-art COVID-19 pandemic, the role of selenium in dealing with COVID-19 disease has been widely discussed due to its importance as an essential micronutrient. This review aims at providing all antiviral activities of nanoselenium (Nano-Se) ever explored using different methods in the literature. We systematically summarize the studied antiviral activities of Nano-Se required to project it as an efficient antiviral system as a function of shape, size, and synthesis method. The outcomes of this article not only introduce Nano-Se to the scientific community but also motivate scholars to adopt Nano-Se to tackle any serious virus such as mutated SARS-CoV-2 to achieve an effective antiviral activity in a desired manner.

A molecular modelling approach for identifying antiviral selenium-containing heterocyclic compounds that inhibit the main protease of SARS-CoV-2: an in silico investigation

Coronavirus disease 2019 (COVID-19), an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been declared a global pandemic by the World Health Organization, and the situation worsens daily, associated with acute increases in case fatality rates. The main protease (Mpro) enzyme produced by SARS-CoV-2 was recently demonstrated to be responsible for not only viral reproduction but also impeding host immune responses. The element selenium (Se) plays a vital role in immune functions, both directly and indirectly. Thus, we hypothesised that Se-containing heterocyclic compounds might curb the activity of SARS-CoV-2 Mpro. We performed a molecular docking analysis and found that several of the selected selenocompounds showed potential binding affinities for SARS-CoV-2 Mpro, especially ethaselen (49), which exhibited a docking score of -6.7 kcal/mol compared with the -6.5 kcal/mol score for GC376 (positive control). Drug-likeness calculations suggested that these compounds are biologically active and possess the characteristics of ideal drug candidates. Based on the binding affinity and drug-likeness results, we selected the 16 most effective selenocompounds as potential anti-COVID-19 drug candidates. We also validated the structural integrity and stability of the drug candidate through molecular dynamics simulation. Using further in vitro and in vivo experiments, we believe that the targeted compound identified in this study (ethaselen) could pave the way for the development of prospective drugs to combat SARS-CoV-2 infections and trigger specific host immune responses.

Ebselen and diphenyl diselenide against fungal pathogens: A systematic review

Fungal infections are one of the most prevalent diseases in the world and there is a lack of new antifungal drug development for these diseases. We conducted a systematic review of the literature regarding the in vitro antifungal activity of the organoselenium compounds ebselen (Eb) and diphenyl diselenide [(PhSe)2]. A systematic review was carried out based on the search for articles with data concerning Minimal Inhibitory Concentration (MIC) values, indexed in international databases and published until August 2020. A total of 2337 articles were found, and, according to the inclusion and exclusion criteria used, 22 articles were included in the study. Inhibitory activity against 96% (200/208) and 95% (312/328) of the pathogenic fungi tested was described for Eb and [(PhSe)2], respectively. Including in these 536 fungal isolates tested, organoselenium activity was highlighted against Candida spp., Cryptococcus ssp., Trichosporon spp., Aspergillus spp., Fusarium spp., Pythium spp., and Sporothrix spp., with MIC values lower than 64 μg/mL. In conclusion, Eb and [(PhSe)2] have a broad spectrum of in vitro inhibitory antifungal activity. These data added with other pharmacological properties of these organoselenium compounds suggest that both compounds are potential future antifungal drugs. Whether MICs toward the upper end of the ranges described here are compatible with efficacious therapy, and whether they may achieve such end as a result of the favorable non-antimicrobial effects of selenium on the host, requires more in vivo testing.

A connectivity map-based drug repurposing study and integrative analysis of transcriptomic profiling of SARS-CoV-2 infection

AIMS

The recent outbreak of COVID-19 has become a global health concern. There are currently no effective treatment strategies and vaccines for the treatment or prevention of this fatal disease. The current study aims to determine promising treatment options for the COVID-19 through a computational drug repurposing approach.

MATERIALS AND METHODS

In this study, we focus on differentially expressed genes (DEGs), detected in SARS-CoV-2 infected cell lines including "the primary human lung epithelial cell line NHBE" and "the transformed lung alveolar cell line A549". Next, the identified DEGs are used in the connectivity map (CMap) analysis to identify similarly acting therapeutic candidates. Furthermore, to interpret lists of DEGs, pathway enrichment and protein network analysis are performed. Genes are categorized into easily interpretable pathways based on their biological functions, and overrepresentation of each pathway is tested in comparison to what is expected randomly.

KEY FINDINGS

The results suggest the effectiveness of lansoprazole, folic acid, sulfamonomethoxine, tolnaftate, diclofenamide, halcinonide, saquinavir, metronidazole, ebselen, lidocaine and benzocaine, histone deacetylase (HDAC) inhibitors, heat shock protein 90 (HSP90) inhibitors, and many other clinically approved drugs as potent drugs against COVID-19 outbreak.

SIGNIFICANCE

Making new drugs remain a lengthy process, so the drug repurposing approach provides an insight into the therapeutics that might be helpful in this pandemic. In this study, pathway enrichment and protein network analysis are also performed, and the effectiveness of some drugs obtained from the CMap analysis has been investigated according to previous researches.

Anti-tubercular profile of new selenium-menadione conjugates against Mycobacterium tuberculosis H37Rv (ATCC 27294) strain and multidrug-resistant clinical isolates

Tuberculosis (TB) is one of the most fatal diseases and is responsible for the infection of millions of people around the world. Most recently, scientific frontiers have been engaged to develop new drugs that can overcome drug-resistant TB. Following this direction, using a designed scaffold based on the combination of two separate pharmacophoric groups, a series of menadione-derived selenoesters was developed with good yields. All products were evaluated for their in vitro activity against Mycobacterium tuberculosis H37Rv and attractive results were observed, especially for the compounds 8a, 8c and 8f (MICs 2.1, 8.0 and 8.1 μM, respectively). In addition, 8a, 8c and 8f demonstrated potent in vitro activity against multidrug-resistant clinical isolates (CDCT-16 and CDCT-27) with promising MIC values ranging from 0.8 to 3.1 μM. Importantly, compounds 8a and 8c were found to be non-toxic against the Vero cell line. The SI value of 8a (>23.8) was found to be comparable to that of isoniazid (>22.7), which suggests the possibility of carrying out advanced studies on this derivative. Therefore, these menadione-derived selenoesters obtained as hybrid compounds represent promising new anti-tubercular agents to overcome TB multidrug resistance.

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New menadione-derived selenoesters were synthesized.

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The compounds demonstrated excellent activity against M. tuberculosis H37Rv.

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8a, 8c and 8f showed potent activity against multidrug resistant clinical isolates.

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Compounds 8a and 8c were found to be non-toxic.

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These organoselenium compounds represent promising new anti-tubercular agents.

Green synthesis of selenium-N-heterocyclic carbene compounds: Evaluation of antimicrobial and anticancer potential

Three benzimidazolium salts (III-V) and respective selenium adducts (VI-VIII) were designed, synthesized and characterized by various analytical techniques (FT-IR and NMR ¹H, ¹³C). Selected salts and respective selenium N-Heterocyclic carbenes (selenium-NHC) adducts were tested in vitro against Cervical Cancer Cell line (Hela), Breast Adenocarcinoma cell line (MCF-7), Retinal Ganglion Cell line (RGC-5) and Mouse Melanoma Cell line (B16F10) using MTT assay and the results were compared with standard drug 5-Fluorouracil. Se-NHC compounds and azolium salts showed significant anticancer potential. Molecular docking studies of compounds (VI, VII and VIII) showed strong binding energies and ligand affinity toward following angiogenic factors: VEGF-A (vascular endothelial growth factor A), EGF (human epidermal growth factor), HIF (Hypoxia-inducible factor) and COX-1 (Cyclooxygenase-1) suggesting that the anticancer activity of adducts (VI, VII and VIII) may be due to their strong anti-angiogenic effect. In addition, compounds III-VIII were screened for their antibacterial and antifungal potential. Adduct VI was found to be potent anti-fungal agent against A. Niger with zone of inhibition (ZI) value 27.01 ± 0.251 mm which is better than standard drug Clotrimazole tested in parallel.

Synthesis and Antifungal Potential of Some Novel Benzimidazole-1,3,4-Oxadiazole Compounds

Discovery of novel anticandidal agents with clarified mechanisms of action, could be a rationalist approach against diverse pathogenic fungal strains due to the rise of resistance to existing drugs. In support to this hypothesis, in this paper, a series of benzimidazole-oxadiazole compounds were synthesized and subjected to antifungal activity evaluation. In vitro activity assays indicated that some of the compounds exhibited moderate to potent antifungal activities against tested Candida species when compared positive control amphotericin B and ketoconazole. The most active compounds 4h and 4p were evaluated in terms of inhibitory activity upon ergosterol biosynthesis by an LC-MS-MS method and it was determined that they inhibited ergosterol synthesis concentration dependently. Docking studies examining interactions between most active compounds and lanosterol 14-α-demethylase also supported the in vitro results.

3-Selenocyanate-indoles as new agents for the treatment of superficial and mucocutaneous infections

The development of resistance to the current antifungal agents is an alarming problem.

Therapeutic applications of selenium-derived compounds

Selenium is a biocompatible element and participates in several biochemical reactions occurring in the human body. Its biocompatibility and minimal toxicity has attracted researchers to develop selenium-based drugs. Hence, recent developments on biomedical applications of selenium-based compounds have been discussed. A structure activity relationship has also been interpreted.

Reaction of bis[(2-chlorocarbonyl)phenyl] Diselenide with Phenols, Aminophenols, and Other Amines towards Diphenyl Diselenides with Antimicrobial and Antiviral Properties

A reaction of bis[(2-chlorocarbonyl)phenyl] diselenide with various mono and bisnucleophiles such as aminophenols, phenols, and amines have been studied as a convenient general route to a series of new antimicrobial and antiviral diphenyl diselenides. The compounds, particularly bis[2-(hydroxyphenylcarbamoyl)]phenyl diselenides and reference benzisoselenazol-3(2H)-ones, exhibited high antimicrobial activity against Gram-positive bacterial species (Enterococcus spp., Staphylococcus spp.), and some compounds were also active against Gram-negative E. coli and fungi (Candida spp., A. niger). The majority of compounds demonstrated high activity against human herpes virus type 1 (HHV-1) and moderate activity against encephalomyocarditis virus (EMCV), while they were generally inactive against vesicular stomatitis virus (VSV).

Thermal and Photoinduced Copper-Promoted C-Se Bond Formation: Synthesis of 2-Alkyl-1,2-benzisoselenazol-3(2H)-ones and Evaluation against Mycobacterium tuberculosis

2-Alkyl-1,2-benzisoselenazol-3(2H)-ones, represented by ebselen (1a), are being studied intensively for a range of medicinal applications. We describe both a new thermal and photoinduced copper-mediated cross-coupling between potassium selenocyanate (KSeCN) and N-substituted ortho-halobenzamides to form 2-alkyl-1,2-benzisoselenazol-3(2H)-ones containing a C-Se-N bond. The copper ligand (1,10-phenanthroline) facilitates C-Se bond formation during heating via a mechanism that likely involves atom transfer (AT), whereas, in the absence of ligand, photoinduced activation likely proceeds through a single electron transfer (SET) mechanism. A library of 15 2-alkyl-1,2-benzisoselenazol-3(2H)-ones was prepared. One member of the library was azide-containing derivative 1j that was competent to undergo a strain-promoted azide-alkyne cycloaddition. The library was evaluated for inhibition of Mycobacterium tuberculosis (Mtb) growth and Mtb Antigen 85C (Mtb Ag85C) activity. Compound 1f was most potent with a minimal inhibitory concentration (MIC) of 12.5 μg/mL and an Mtb Ag85C apparent IC₅₀ of 8.8 μM.

Ebselen exerts antifungal activity by regulating glutathione (GSH) and reactive oxygen species (ROS) production in fungal cells

BACKGROUND

Ebselen, an organoselenium compound and a clinically safe molecule has been reported to possess potent antifungal activity, but its antifungal mechanism of action and in vivo antifungal activity remain unclear.

METHODS

The antifungal effect of ebselen was tested against Candida albicans, C. glabrata, C. tropicalis, C. parapsilosis, Cryptococcus neoformans, and C. gattii clinical isolates. Chemogenomic profiling and biochemical assays were employed to identify the antifungal target of ebselen. Ebselen's antifungal activity in vivo was investigated in a Caenorhabditis elegans animal model.

RESULTS

Ebselen exhibits potent antifungal activity against both Candida spp. and Cryptococcus spp., at concentrations ranging from 0.5 to 2μg/ml. Ebselen rapidly eradicates a high fungal inoculum within 2h of treatment. Investigation of the drug's antifungal mechanism of action indicates that ebselen depletes intracellular glutathione (GSH) levels, leading to increased production of reactive oxygen species (ROS), and thereby disturbs the redox homeostasis in fungal cells. Examination of ebselen's in vivo antifungal activity in two Caenorhabditis elegans models of infection demonstrate that ebselen is superior to conventional antifungal drugs (fluconazole, flucytosine and amphotericin) in reducing Candida and Cryptococcus fungal load.

CONCLUSION

Ebselen possesses potent antifungal activity against clinically relevant isolates of both Candida and Cryptococcus by regulating GSH and ROS production. The potent in vivo antifungal activity of ebselen supports further investigation for repurposing it for use as an antifungal agent.

GENERAL SIGNIFICANCE

The present study shows that ebselen targets glutathione and also support that glutathione as a potential target for antifungal drug development.

Protective effects of novel organic selenium compounds against oxidative stress in the nematode Caenorhabditis elegans

Organic selenium compounds possess numerous biological properties, including antioxidant activity. Yet, the high toxicity of some of them, such as diphenyl diselenide (DPDS), is a limiting factor in their current usage. Accordingly, we tested four novel organic selenium compounds in the non-parasite nematode Caenorhabditis elegans and compared their efficacy to DPDS. The novel organic selenium compounds are β-selenoamines (1-phenyl-3-(p-tolylselanyl)propan-2-amine (C1) and 1-(2-methoxyphenylselanyl)-3-phenylpropan-2-amine (C2) and analogs of DPDS (1,2-bis (2-methoxyphenyl) diselenide (C3) and 1,2-bisp-tolyldiselenide (C4). Synchronized worms at the L4 larval stage were exposed for one hour in M9 buffer to these compounds. Oxidative stress conditions were induced by juglone (200 μM) and heat shock (35 °C). Moreover, we evaluated Caenorhabditis elegans behavior, GST-4::GFP (glutathione S-transferase) expression and the activity of acetylcholinesterase (AChE). All tested compounds efficiently restored viability in juglone stressed worms. However, DPDS, C2, C3 and C4 significantly decreased the defecation cycle time. Juglone-induced GST-4::GFP expression was not attenuated in worms pretreated with the novel compounds, except with C2. Finally, AChE activity was reduced by DPDS, C2, C3 and C4. To our knowledge, this is study firstly showed the effects of C1, C2, C3 and C4 selenium-derived compounds in Caenorhabditis elegans. Low toxic effects were noted, except for reduction in the defecation cycle, which is likely associated with AChE inhibition. The juglone-induced stress (reduced viability) was fully reversed by compounds to control animal levels. C2 was also efficient in reducing the juglone-induced GST-4::GFP expression, suggesting the latter may mediate the stress induced by this compound. Future studies could be profitably directed at addressing additional molecular mechanisms that mediate the protective effects of these novel organic selenium compounds.

Advances in targeting the vacuolar proton-translocating ATPase (V-ATPase) for anti-fungal therapy

Vacuolar proton-translocating ATPase (V-ATPase) is a membrane-bound, multi-subunit enzyme that uses the energy of ATP hydrolysis to pump protons across membranes. V-ATPase activity is critical for pH homeostasis and organelle acidification as well as for generation of the membrane potential that drives secondary transporters and cellular metabolism. V-ATPase is highly conserved across species and is best characterized in the model fungus Saccharomyces cerevisiae. However, recent studies in mammals have identified significant alterations from fungi, particularly in the isoform composition of the 14 subunits and in the regulation of complex disassembly. These differences could be exploited for selectivity between fungi and humans and highlight the potential for V-ATPase as an anti-fungal drug target. Candida albicans is a major human fungal pathogen and causes fatality in 35% of systemic infections, even with anti-fungal treatment. The pathogenicity of C. albicans correlates with environmental, vacuolar, and cytoplasmic pH regulation, and V-ATPase appears to play a fundamental role in each of these processes. Genetic loss of V-ATPase in pathogenic fungi leads to defective virulence, and a comprehensive picture of the mechanisms involved is emerging. Recent studies have explored the practical utility of V-ATPase as an anti-fungal drug target in C. albicans, including pharmacological inhibition, azole therapy, and targeting of downstream pathways. This overview will discuss these studies as well as hypothetical ways to target V-ATPase and novel high-throughput methods for use in future drug discovery screens.

Ebsulfur is a benzisothiazolone cytocidal inhibitor targeting the trypanothione reductase of Trypanosoma brucei

Trypanosoma brucei is the causing agent of African trypanosomiasis. These parasites possess a unique thiol redox system required for DNA synthesis and defense against oxidative stress. It includes trypanothione and trypanothione reductase (TryR) instead of the thioredoxin and glutaredoxin systems of mammalian hosts. Here, we show that the benzisothiazolone compound ebsulfur (EbS), a sulfur analogue of ebselen, is a potent inhibitor of T. brucei growth with a favorable selectivity index over mammalian cells. EbS inhibited the TryR activity and decreased non-protein thiol levels in cultured parasites. The inhibition of TryR by EbS was irreversible and NADPH-dependent. EbS formed a complex with TryR and caused oxidation and inactivation of the enzyme. EbS was more toxic for T. brucei than for Trypanosoma cruzi, probably due to lower levels of TryR and trypanothione in T. brucei. Furthermore, inhibition of TryR produced high intracellular reactive oxygen species. Hydrogen peroxide, known to be constitutively high in T. brucei, enhanced the EbS inhibition of TryR. The elevation of reactive oxygen species production in parasites caused by EbS induced a programmed cell death. Soluble EbS analogues were synthesized and cured T. brucei brucei infection in mice when used together with nifurtimox. Altogether, EbS and EbS analogues disrupt the trypanothione system, hampering the defense against oxidative stress. Thus, EbS is a promising lead for development of drugs against African trypanosomiasis.

Diphenyl diselenide in vitro and in vivo activity against the oomycete Pythium insidiosum

This study evaluated the in vitro activity of diphenyl diselenide against 19 Pythium insidiosum isolates and the in vivo therapeutic response of rabbits with experimentally induced pythiosis. In vitro: susceptibility tests were performed using the broth macrodilution method in accordance with the CLSI document M38-A2. The criteria for interpretation were as follows: MIC-1 and MIC-2 (inhibition of 90% and 100% of mycelium growth, respectively) and the minimum fungicide concentration (MIC-3). In vivo: twenty rabbits were divided into four groups with five animals each and treated for 40 consecutive days: groups 1 and 2 (experimentally induced pythiosis) were treated with diphenyl diselenide (10mg/kg/day) and canola oil (1 mL/kg/day), respectively; groups 3 and 4 (controls) were treated with canola oil (1 mL/kg/day) and diphenyl diselenide (10mg/kg/day), respectively. Toxicity was evaluated using biochemical and haematological parameters. In vitro susceptibility tests showed that 89.4% of isolates had a MIC-1 ≤ 0.5 μg/mL, 84.2% of isolates had a MIC-2 ≤ 1.0 μg/mL and 94.7% of isolates had a MIC-3 ≤ 2.0 μg/mL. The in vivo assay suggested that this compound has a fungistatic activity, and the biochemical and haematological parameters indicated that there was no renal, hepatic or haematological toxicity. The comparison of the unsaturated iron binding capacity levels between animals with and without pythiosis suggested the involvement of iron metabolism in the pathogenesis of pythiosis. This study demonstrated the absence of detectable toxicity caused by diphenyl diselenide and the in vitro fungicidal and in vivo fungistatic activities of this drug, which makes it an option for future therapeutic approaches in the treatment of pythiosis.

Inhibition of vesicular stomatitis virus replication in the course of HIV infection in patients with different stages of immunodeficiency

The replication of vesicular stomatitis virus (VSV) in isolated human leukocytes has been used to measure the level of nonspecific antiviral immunity. However, during infection with some pathogens, the main effect observed is caused by interaction between the pathogen and VSV. This was also noted in advanced stages of HIV infection, when an inverse association between HIV viral load and VSV replication was found. The mutual effect was markedly stronger than the correlation between the VSV replication level and CD4(+) T-cell count. Since successful antiretroviral therapy is associated with a decrease in HIV viremia to undetectable levels, the effect of such therapy on VSV replication was expected and confirmed in this investigation. In fact, increased VSV titers were observed together with decreased HIV viral load, particularly in the case of efficient therapeutic schemes, for example those including lopinavir/ritonavir. The results showed that VSV replication capacity reflected the progression of HIV infection. Moreover, the presence of interferon in the plasma of AIDS patients was found to be only partially responsible for the inhibition of VSV replication. The results suggest a specific HIV-VSV interaction, whether direct or indirect. Thus the VSV replication assay may be applied in evaluating the stage of HIV infection.

Crucial role of selenium in the virucidal activity of benzisoselenazol-3(2H)-ones and related diselenides

Various N-substituted benzisoselenazol-3(2H)-ones and their non-selenium-containing analogues have been synthesized and tested against selected viruses (HHV-1, EMCV and VSV) to determine the extent to which selenium plays a role in antiviral activity. The data presented here show that the presence of selenium is crucial for the antiviral properties of benzisoselenazol-3(2H)-ones since their isostructural analogues having different groups but lacking selenium either did not show any antiviral activity or their activity was substantially lower. The open-chain analogues of benzisoselenazol-3(2H)-ones--diselenides also exhibited high antiviral activity while selenides and disulfides were completely inactive towards model viruses.

Antibacterial activities of novel diselenide-bridged bis(porphyrin)s on Staphylococcus aureus investigated by microcalorimetry

The actions of two novel diselenide-bridged bis(porphyrin)s (1 and 2) on Staphylococcus aureus growth was investigated by microcalorimetry at 37.00 degrees C, compared with that of Na2SeO3. Differences in their capacities to inhibit the growth metabolism of S. aureus were observed. By analyzing the power-time curves, crucial parameters such as the rate constant of bacterial growth (k), inhibitory rate (I), and generation time (tG) were determined. The growth rate constant (k) of S. aureus (in the log phase) in the presence of the drugs decreased with increasing concentrations of the drugs regularly. The relationship of k and c is nearly linear for diselenide-bridged bis(porphyrin) 2. The sequence of the antibacterial activities of these selenium compounds tested was 2 > 1 > Na2SeO3.

New organoselenium compounds active against pathogenic bacteria, fungi and viruses

Different N-substituted benzisoselenazol-3(2H)-ones, analogues of ebselen were designed as new antiviral and antimicrobial agents. We report their synthesis, chemical properties as well as study on biological activity against broad spectrum of pathogenic microorganisms (Staphylococcus aureus, Staphylococcus simulans, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Candida albicans, Aspergillus niger) and viruses (herpes simplex virus type 1 (HSV-1), encephalomyocarditis virus (EMCV), vesicular stomatitis virus (VSV)), in vitro. Most of them exhibited high activity against viruses (HSV-1, EMCV) and gram-positive bacteria strains (S. aureus, S. simulans), while their activity against gram-negative bacteria strains (E. coli, P. aeruginosa, K. pneumoniae) was substantially lower. Some of tested compounds were active against yeast C. albicans and filamentous fungus A. niger.

Effect of oral gavage treatment with ZnAL42 and other metallo-ion formulations on influenza A H5N1 and H1N1 virus infections in mice

Avian influenza H5N1 infections can cause severe, lethal human infections. Whether influenza A virus treatments effectively ameliorate avian influenza H5N1 human infections is uncertain. The research objective was to evaluate the efficacy of novel zinc and other metallo-ion formulations in two influenza A mouse models. Mice infected with influenza A/Duck/MN/1525/81 (H5N1) virus were treated orally 48 h before virus exposure and then twice daily for 13 days with ZnAL42. The optimal dosing regimen for ZnAL42 was achieved at 17.28 mg/kg 48 h prior to virus exposure, twice daily for 7 days. The survival rate was 80% compared with 10% in the untreated control group and a 100% survival rate with ribavirin (75 mg/kg/day, twice a day for 5 days, beginning 4 h before virus exposure). ZnAL42 treatment significantly lessened the decline in arterial oxygen saturation (SaO2; P < 0.001). This regimen was also well tolerated by the mice. Manganese and selenium formulations were not inhibitory to virus replication when given therapeutically. Mice were also infected with influenza A/NWS/33 (H1N1) virus and were treated 48 h before virus exposure with three dosages of ZnAL42 (8.64, 1.46 or 0.24 mg/kg/day). Treatment was by oral gavage twice daily for 13 days. The highest dose of ZnAL42 was significantly inhibitory to the virus infection as seen by prevention of deaths and lessening of decline in SaO2. The data suggest that the prophylactic use of ZnAL42 is effective against avian influenza H5N1 or H1N1 virus infection in mice and should be further explored as an option for treating human influenza virus infections.