N-(4-acetamidophenyl)-5-acetylfuran-2-carboxamide as a novel orally available diuretic that targets urea transporters with improved PD and PK properties

Urea transporters (UTs) have been identified as new targets for diuretics. Functional deletion of UTs led to urea-selective urinary concentrating defects with relative salt sparing. In our previous study, a UT inhibitor with a diarylamide scaffold, which is denoted as 11a, was demonstrated as the first orally available UT inhibitor. However, the oral bioavailability of 11a was only 4.38%, which obstructed its clinical application. In this work, by replacing the nitro group of 11a with an acetyl group, 25a was obtained. Compared with 11a, 25a showed a 10 times stronger inhibitory effect on UT-B (0.14 μM vs. 1.41 μM in rats, and 0.48 μM vs. 5.82 μM in mice) and a much higher inhibition rate on UT-A1. Moreover, the metabolic stability both in vitro and in vivo and the drug-like properties (permeability and solubility) of 25a were obviously improved compared with those of 11a. Moreover, the bioavailability of 25a was 15.18%, which was 3 times higher than that of 11a, thereby resulting in significant enhancement of the diuretic activities in rats and mice. 25a showed excellent potential for development as a promising clinical diuretic candidate for targeting UTs to treat diseases that require long-term usage of diuretics, such as hyponatremia.

Anti-influenza A virus activity of two Newtonia species and the isolated compound myricetin-3-o-rhamnoside

BACKGROUND

Some viruses play a key role in the disturbance of the digestive system. The common viruses which cause infectious diarrhoea (gastroenteritis) include astrovirus, caliciviruses, coronavirus and torovirus which are single-stranded RNA viruses. Influenza A virus (H1N1) also causes diarrhoea in addition to being associated with respiratory symptoms. In preliminary studies, Newtonia hildebrandtii and N. buchananii leaf extracts had good antibacterial activity against some bacteria implicated in causing diarrhoea. The aim of this study was to evaluate the anti-influenza activity of two Newtonia species extracts and the isolated compound (myricitrin).

METHODS

N. hildebrandtii and N. buchananii acetone, and MeOH: DCM (methanol-dichloromethane) leaf and stem extracts, and an antibacterial compound myricetin-3-o-rhamnoside (myricitrin), isolated from N. buchananii, were evaluated for their antiviral efficacy against influenza A virus (IAV) PR8/34/H1N1 as a model organism. The MTT and hemagglutination assays were used to assess the extracts and compound interference with cell viability and viral surface HA glycoprotein. The quantitative real-time PCR was performed to assess the viral load.

RESULTS

Plant extracts of N. hildebrandtii and N. buchananii were effective against IAV. The extracts in combination with H1N1 showed highly significant antiviral activity (P < 0.01) and maintained cell viabilities (P < 0.05). Myricitrin was non-cytotoxic at concentration 104 μg/ml. Myricitrin was most effective against IAV in a co-penetration combined treatment, thereby confirming the inhibitory effect of this compound in the viral attachment and entry stages. Myricitrin treatment also resulted in the highest viability of the cells in co-penetration treatment. The activity of myricitrin indicates the potential of the extracts in controlling viral infection at the attachment stage. The antiviral effect of myricitrin on IAV load in MDCK cell culture was confirmed using quantitative real-time PCR.

CONCLUSION

Data from this study support further research and development on Newtonia hildebrandtii, Newtonia buchananii and myricitrin to address diarrhoea and related conditions caused by viruses in both human and veterinary medicine. Further work needs to be conducted on the activity of the extracts and the purified compound on other viruses of importance which have similar symptoms to influenza virus such as the coronavirus which led to a recent global pandemic.

Topology-Matching Design of an Influenza-Neutralizing Spiky Nanoparticle-Based Inhibitor with a Dual Mode of Action

In this study, we demonstrate the concept of "topology-matching design" for virus inhibitors. With the current knowledge of influenza A virus (IAV), we designed a nanoparticle-based inhibitor (nano-inhibitor) that has a matched nanotopology to IAV virions and shows heteromultivalent inhibitory effects on hemagglutinin and neuraminidase. The synthesized nano-inhibitor can neutralize the viral particle extracellularly and block its attachment and entry to the host cells. The virus replication was significantly reduced by 6 orders of magnitude in the presence of the reverse designed nano-inhibitors. Even when used 24 hours after the infection, more than 99.999 % inhibition is still achieved, which indicates such a nano-inhibitor might be a potent antiviral for the treatment of influenza infection.

Isocorilagin, isolated from Canarium album (Lour.) Raeusch, as a potent neuraminidase inhibitor against influenza A virus

Canarium album (Lour.) Raeusch (C. album) as a normally medicinal and edible plant has been used widely in Asian countries and is considered a source of phytochemicals that are beneficial to human health. Here, we showed at the first time isocorilagin, a polyphenolic compound isolated from C. album, displayed antiviral activity against diverse strains of influenza A virus (IAV), including A/Puerto Rico/8/34 (H1N1), A/Aichi/2/68 (H3N2) and NA-H274Y (H1N1) with IC₅₀ value of 9.19 ± 1.99, 23.72 ± 2.51 and 4.64 ± 3.01 μM, respectively. Further mechanistic studies revealed that it clearly inhibited neuraminidase activity of IAV and directly influenced the virus release. The molecular docking studies presented isocorilagin could bind to the highly conserved residues in the active sites of NA, implying that isocorilagin may be effective against various influenza strains and not susceptible to produce drug resistance. Taken together, the results strongly suggest that isocorilagin has potential to be an effective, safe and affordable neuraminidase inhibitor against a diverse panel of IAV strains. More importantly, our work expands the biological activities of C. album extracts and provide a new option for the development of anti-influenza drug.

[SELECTIVE EFFICACY OF GEORGIAN LEGUME EXTRACTS ON JURKAT AND MDCK CELLS]

The goal of our study was to establish the anti- proapoptotic activity of the common in Georgia crops on the Jurkat and MDCK cells. Extracts of various varieties of beans (Tirkmela, Batumi meadow, Shulavera, Udelebi, as well as green peas, Lens Culinaris lentils, soy beans) were added to the intact or incubated under oxidative stress conditions Jurkat and MDCK cells. Cell viability (apoptosis intensity) was determined by a cell proliferative activity test (MTT test). Correlation and statistical analysis of ANOVA was performed using the package (SPSS version 11.0). In the presented study the selective effectiveness of extracts with different antioxidant activity on intact and incubated under oxidative stress Jurkat and MDCK cells was revealed, related with different sensitivity of cells to the oxidative stress. In normal MDCK epithelial cells, resistant to redox-active factors (H2O2), inverse relationship between the intensity of apoptosis and the antiradical potential of the extract was found; in leukemia transformated Jurkat cells, characterized by high sensitivity to oxidants (H2O2), a violation of the redox-dependent anti-apoptotic cell protection mechanisms was revealed, which is manifested by the absence of regularity of the cytoprotective / cytotoxic effects of the extracts on intact and incubated cells under oxidative stress conditions. These results can be used in the development of schemes of anti-tumor and anti-inflammatory therapy.

Microtubule-Targeting 7-Deazahypoxanthines Derived from Marine Alkaloid Rigidins: Exploration of the N3 and N9 Positions and Interaction with Multidrug-Resistance Proteins

Our laboratories have been investigating synthetic analogues of marine alkaloid rigidins that possess promising anticancer activities. These analogues, based on the 7-deazahypoxanthine skeleton, are available in one- or two-step synthetic sequences and exert cytotoxicity by disrupting microtubule dynamics in cancer cells. In the present work we extended the available structure-activity relationship (SAR) data to N3- and N9-substituted derivatives. Although N3 substitution results in loss of activity, the N9-substituted compounds retain nanomolar antiproliferative activities and the anti-tubulin mode of action of the original unsubstituted compounds. Furthermore, our results also demonstrate that multidrug-resistance (MDR) proteins do not confer resistance to both N9-unsubstituted and -substituted compounds. It was found that sublines overexpressing ABCG2, ABCC1, and ABCB1 proteins are as responsive to the rigidin analogues as their parental cell lines. Thus, the study reported herein provides further impetus to investigate the rigidin-inspired 7-deazahypoxanthines as promising anticancer agents.

Silver Nanoparticles Impair Retinoic Acid-Inducible Gene I-Mediated Mitochondrial Antiviral Immunity by Blocking the Autophagic Flux in Lung Epithelial Cells

Silver nanoparticles (AgNPs) are microbicidal agents which could be potentially used as an alternative to antivirals to treat human infectious diseases, especially influenza virus infections where antivirals have generally proven unsuccessful. However, concerns about the use of AgNPs on humans arise from their potential toxicity, although mechanisms are not well-understood. We show here, in the context of an influenza virus infection of lung epithelial cells, that AgNPs down-regulated influenza induced CCL-5 and -IFN-β release (two cytokines important in antiviral immunity) through RIG-I inhibition, while enhancing IL-8 production, a cytokine important for mobilizing host antibacterial responses. AgNPs activity was independent of coating and was not observed with gold nanoparticles. Down-stream analysis indicated that AgNPs disorganized the mitochondrial network and prevented the antiviral IRF-7 transcription factor influx into the nucleus. Importantly, we showed that the modulation of RIG-I-IRF-7 pathway was concomitant with inhibition of either classical or alternative autophagy (ATG-5- and Rab-9 dependent, respectively), depending on the epithelial cell type used. Altogether, this demonstration of a AgNPs-mediated functional dichotomy (down-regulation of IFN-dependent antiviral responses and up-regulation of IL-8-dependent antibacterial responses) may have practical implications for their use in the clinic.

Bismuth antimicrobial drugs serve as broad-spectrum metallo-β-lactamase inhibitors

Drug-resistant superbugs pose a huge threat to human health. Infections by Enterobacteriaceae producing metallo-β-lactamases (MBLs), e.g., New Delhi metallo-β-lactamase 1 (NDM-1) are very difficult to treat. Development of effective MBL inhibitors to revive the efficacy of existing antibiotics is highly desirable. However, such inhibitors are not clinically available till now. Here we show that an anti-Helicobacter pylori drug, colloidal bismuth subcitrate (CBS), and related Bi(III) compounds irreversibly inhibit different types of MBLs via the mechanism, with one Bi(III) displacing two Zn(II) ions as revealed by X-ray crystallography, leading to the release of Zn(II) cofactors. CBS restores meropenem (MER) efficacy against MBL-positive bacteria in vitro, and in mice infection model, importantly, also slows down the development of higher-level resistance in NDM-1-positive bacteria. This study demonstrates a high potential of Bi(III) compounds as the first broad-spectrum B1 MBL inhibitors to treat MBL-positive bacterial infection in conjunction with existing carbapenems.

Facile functionalization at the C4 position of pyrimidine nucleosides via amide group activation with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and biological evaluations of the products

Reactions of O-t-butyldimethylsilyl-protected thymidine, 2'-deoxyuridine, and 3'-azidothymidine (AZT) with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) leads to activation of the C4 amide carbonyl by formation of putative O4-(benzotriazol-1-yl) derivatives. Subsequent substitution with alkyl and aryl amines, thiols, and alcohols leads to facile functionalization at this position. Reactions with amines and thiols were conducted either as a two-step, one-pot transformation, or as a one-step conversion. Reactions with alcohols were conducted as two-step, one-pot transformations. In the course of these investigations, the formation of 1-(4-pyrimidinyl)-1H-benzotriazole-3-oxide derivatives from the pyrimidine nucleosides was identified. However, these too underwent conversion to the desired products. Products obtained from AZT were converted to the 3'-amino derivatives by catalytic reduction. All products were assayed for their abilities to inhibit cancer cell proliferation and for antiviral activities. Many were seen to be active against HIV-1 and HIV-2, and one was active against herpes simplex virus-1 (HSV-1).

Effects of cranberry extract on prevention of urinary tract infection in dogs and on adhesion of Escherichia coli to Madin-Darby canine kidney cells

OBJECTIVE

To determine effects of cranberry extract on development of urinary tract infection (UTI) in dogs and on adherence of Escherichia coli to Madin-Darby canine kidney (MDCK) cells.

ANIMALS

12 client-owned dogs (in vivo experiment) and 6 client-owned dogs (in vitro experiment).

PROCEDURES

12 dogs with a history of recurrent UTI received an antimicrobial (n = 6) or cranberry extract (6) orally for 6 months. Dogs were monitored for a UTI. For the in vitro experiment, cranberry extract was orally administered to 6 dogs for 60 days. Voided urine samples were collected from each dog before and 30 and 60 days after onset of extract administration. Urine was evaluated by use of a bacteriostasis assay. An antiadhesion assay and microscopic examination were used to determine inhibition of bacterial adherence to MDCK cells.

RESULTS

None of the 12 dogs developed a UTI. The bacteriostasis assay revealed no zone of inhibition for any urine samples. Bacterial adhesion was significantly reduced after culture with urine samples obtained at 30 and 60 days, compared with results for urine samples obtained before extract administration. Microscopic examination revealed that bacterial adherence to MDCK cells was significantly reduced after culture with urine samples obtained at 30 and 60 days, compared with results after culture with urine samples obtained before extract administration.

CONCLUSIONS AND CLINICAL RELEVANCE

Oral administration of cranberry extract prevented development of a UTI and prevented E coli adherence to MDCK cells, which may indicate it has benefit for preventing UTIs in dogs.

1,6-Bis[(benzyloxy)methyl]uracil derivatives-Novel antivirals with activity against HIV-1 and influenza H1N1 virus

A series of 1,6-bis[(benzyloxy)methyl]uracil derivatives combining structural features of both diphenyl ether and pyridone types of NNRTIs were synthesized. Target compounds were found to inhibit HIV-1 reverse transcriptase at micro- and submicromolar levels of concentrations and exhibited anti-HIV-1 activity in MT-4 cell culture, demonstrating resistance profile similar to first generation NNRTIs. The synthesized compounds also showed profound activity against influenza virus (H1N1) in MDCK cell culture without detectable cytotoxicity. The lead compound of this assay appeared to exceed rimantadine, amantadine, ribavirin and oseltamivir carboxylate in activity. The mechanism of action of 1,6-bis[(benzyloxy)methyl]uracils against influenza virus is currently under investigation.

Characterization of Neuraminidase Inhibitors in Korean Papaver rhoeas Bee Pollen Contributing to Anti-Influenza Activities In Vitro

The active constituents of Korean Papaver rhoeas bee pollen conferring neuraminidase inhibitory activities (H1N1, H3N2, and H5N1) were investigated. Six flavonoids and one alkaloid were isolated and characterized by nuclear magnetic resonance and mass spectrometry data. These included kaempferol-3-sophoroside (1), kaempferol-3-neohesperidoside (2), kaempferol-3-sambubioside (3), kaempferol-3-glucoside (4), quercetin-3-sophoroside (5), luteolin (6), and chelianthifoline (7). All compounds showed neuraminidase inhibitory activities with IC50 values ranging from 10.7 to 151.1 µM. The most potent neuraminidase inhibitor was luteolin, which was the dominant content in the ethyl acetate fraction. All tested compounds displayed noncompetitive inhibition of H3N2 neuraminidase. Furthermore, compounds 1-7 all reduced the severity of virally induced cytopathic effects as determined by the Madin-Darby canine kidney cell-based assay showing antiviral activity with IC50 values ranging from 10.7 to 33.4 µM (zanamivir: 58.3 µM). The active compounds were quantified by high-performance liquid chromatography, and the total amount of compounds 1-7 made up about 0.592 g/100 g bee pollen, contributing a rich resource of a natural antiviral product.

Modulation of CYPs, P-gp, and PXR by Eschscholzia californica (California Poppy) and Its Alkaloids

Eschscholzia californica, a native US plant, is traditionally used as a sedative, analgesic, and anxiolytic herb. With the rapid rise in the use of herbal supplements together with over-the-counter and prescription drugs, the risk for potential herb-drug interactions is also increasing. Most of the clinically relevant pharmacokinetic drug interactions occur due to modulation of cytochrome P450 enzymes (CYPs), P-glycoprotein, and the pregnane X receptor by concomitantly used herbs. This study aimed to determine the effects of an EtOH extract, aqueous extract (tea), basic CHCl3 fractions, and isolated major alkaloids, namely protopine (1), escholtzine (2), allocryptopine (3), and californidine (4), of E. californica on the activity of cytochrome P450s, P-glycoprotein and the pregnane X receptor. The EtOH extract and fractions showed strong time-dependent inhibition of CYP 3A4, CYP 2C9, and CYP 2C19, and reversible inhibition of CYP 2D6. Among the alkaloids, escholtzine (2) and allocryptopine (3) exhibited time-dependent inhibition of CYP 3A4, CYP 2C9, and CYP 2C19 (IC50 shift ratio > 2), while protopine (1) and allocryptopine (3) showed reversible inhibition of CYP 2D6 enzyme. A significant activation of the pregnane X receptor (> 2-fold) was observed with the EtOH extract, basic CHCl3 fraction, and alkaloids (except protopine), which resulted into an increased expression of mRNA and the activity of CYP 3A4 and CYP 1A2. The expression of P-glycoprotein was unaffected. However, aqueous extract (tea) and its main alkaloid californidine (4) did not affect cytochrome P450s, P-glycoprotein, or the pregnane X receptor. This data suggests that EtOH extract of E. californica and its major alkaloids have a potential of causing interactions with drugs that are metabolized by cytochrome P450s, while the tea seems to be safer.

Differential Sensitivity of Madin-darby Canine Kidney (MDCK) Cells to Epinephrine

Catecholamines regulate a variety of cellular functions in the mammalian kidney. The present study was aimed to investigate the differential sensitivity of Madin-Darby Kidney Cells (MDCK cells) to epinephrine in a dose-dependent manner. The loss of adhesion and altered cell shape were observed in MDCK cells. The presence of apoptosis and necrosis were studied by the fluorescence microscope and Confocal Laser Scanning Microscope (CLSM). Scanning Electron Microscope (SEM) analysis showed several surface microvilli, and cells were rounded having ruffled and crenated surface. Agarose gel electrophoresis study showed the presence of smearing, which further confirms the occurrence of necrosis. The fluorescence staining study showed the increased reactive oxygen species (ROS) level. Up-regulation of p53, bax, and caspase 3 mRNA expressions was evidenced by quantitative PCR (qPCR). Caspase 3 activity was also increased in epinephrine treated cells. Our experimental results do not imply that the epinephrine should not be used in the clinical treatments. However, our results add a research note of caution on the possible cytotoxic effect of maximal doses of epinephrine over a prolonged time.

Bioactive Sesquiterpenes and Lignans from the Fruits of Xanthium sibiricum

Seven new sesquiterpenes (1, 3-8), a new sesquiterpene natural product (2), and two new lignans (9 and 10), together with 15 known compounds, were isolated from the fruits of Xanthium sibiricum. The structures of the new compounds were established by NMR spectroscopic analysis, ECD calculations, and Mo2(OAc)4-induced circular dichroism, with the structures of 1 and 4 confirmed by single-crystal X-ray diffraction. Compound 1 is the first example of a 3/5/6/5 tetracyclic eudesmane sesquiterpene lactone formed at C-6 and C-7. In turn, compound 4 is the first example of a natural xanthane tetranorsesquiterpene, while compounds 5-8 are the first xanthane trinorsesquiterpenes found to date. Compounds 8, 11-15, 17, and 24 exhibited indirect anti-inflammatory activity by suppressing the lipopolysaccharide-induced proinflammatory factors in BV2 microglial cells, with IC50 values between 1.6 and 8.5 μM. Furthermore, compounds 13 and 17 exhibited anti-inflammatory activity against ear edema in mice produced by croton oil, with inhibition rates of 46.9% and 37.7%, respectively. Compounds 8, 11, 12, 23, and 24 exhibited potent activity against influenza A virus (A/FM/1/47, H1N1) with IC50 values between 3.7 and 8.4 μM.

Semisynthetic teicoplanin derivatives as new influenza virus binding inhibitors: synthesis and antiviral studies

In order to obtain new, cluster-forming antibiotic compounds, teicoplanin pseudoaglycone derivatives containing two lipophilic n-octyl chains have been synthesized. The compounds proved to be poor antibacterials, but, surprisingly, they exhibited potent anti-influenza virus activity against influenza A strains. This antiviral action was related to inhibition of the binding interaction between the virus and the host cell. Related analogs bearing methyl substituents in lieu of the octyl chains, displayed no anti-influenza virus activity. Hence, an interaction between the active, dually n-octylated compounds and the lipid bilayer of the host cell can be postulated, to explain the observed inhibition of influenza virus attachment.

Relationship between polyphenol content and anti-influenza viral effects of berries

BACKGROUND

Berries are known to have many kinds of biological activities. We focused on their antiviral effect, which has not yet been well evaluated.

RESULTS

We compared the anti-influenza viral effects of berries belonging to the genus Vaccinium - 35 species of blueberry (Vaccinium cyanococcus), the Natsuhaze (Vaccinium oldhamii), bilberry (Vaccinium myrtillus) and cranberry (Vaccinium oxycoccos)- with those belonging to the genus Ribes, i.e. blackcurrant (Ribes nigrum). Only Elliott and Legacy among Northern Highbush varieties but many Rabbiteye varieties such as Austin, Baldwin, Brightblue, Festival, T-100 and Tifblue showed anti-influenza viral activity. Natsuhaze, bilberry, cranberry and blackcurrant had high antiviral effects. A relationship was observed between the antiviral effect and total polyphenol content.

CONCLUSIONS

Antiviral effects were found to differ markedly between berry species. Rabbiteye varieties tended to have higher antiviral effects than Northern, Southern and Half Highbush blueberry varieties. We also found that Natsuhaze, which has recently been harvested in Japan as a potential functional food, had an antiviral effect comparable to that of bilberry, cranberry and blackcurrant. There was a positive relationship between antiviral activity and polyphenol content, indicating the possibility that polyphenol is one of the key factors in the antiviral effects of berries.

[Design of deoxyribozymes for inhibition of influenza A virus]

Influenza A viruses take a significant place in human and animal pathology causing epidemics and epizootics. Therefore, the development of new antiflu drugs has become more and more urgent. Deoxyribozymes can be considered as promising antiviral agents due to their ability to efficiently and highly specifically cleave RNA molecules. In this study, a number ofgenomic sequences of the most relevant influenza A virus subtypes, H5N1, H3N2, and H1N1, were analyzed. Conservative regions were revealed in five the least variable segments of the fragmented viral RNA genome, and potential sites of their cleavage with "10-23" deoxyribozymes were determined. 46 virus-specific 33-mer deoxyribozymes with the general structure of 5'N8AGGCTAGCTACAACGAN9 were designed and synthesized. Screening of the antiviral activity of these agents in conjugation with lipofectin on the Madin-Darby Canine Kidney cells infected with highly pathogenic avian influenza virus A/chicken/Kurgan/05/2005 (H5N1) revealed 17 deoxyribozymes, which suppressed the titer of virus cytopathicity by more than 2.5 IgTCID50/mL (i.e. the virus neutralization index was more than 300), with five of them suppressing the virus titer by a factor of 1000 and more. The most active deoxyribozymes appeared to be specific to segment 5 of the influenza A virus genome, which encoded nucleoprotein (NP).