| 1. |
- Guimond, S. E., et al.
(författare)
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Synthetic Heparan Sulfate Mimetic Pixatimod (PG545) Potently Inhibits SARS-CoV-2 by Disrupting the Spike-ACE2 Interaction
- 2022
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Ingår i: ACS Central Science. - : American Chemical Society (ACS). - 2374-7943 .- 2374-7951. ; 8:5, s. 527-545
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Tidskriftsartikel (refereegranskat)abstract
- Heparan sulfate (HS) is a cell surface polysaccharide recently identified as a coreceptor with the ACE2 protein for the S1 spike protein on SARS-CoV-2 virus, providing a tractable new therapeutic target. Clinically used heparins demonstrate an inhibitory activity but have an anticoagulant activity and are supply-limited, necessitating alternative solutions. Here, we show that synthetic HS mimetic pixatimod (PG545), a cancer drug candidate, binds and destabilizes the SARS-CoV-2 spike protein receptor binding domain and directly inhibits its binding to ACE2, consistent with molecular modeling identification of multiple molecular contacts and overlapping pixatimod and ACE2 binding sites. Assays with multiple clinical isolates of SARS-CoV-2 virus show that pixatimod potently inhibits the infection of monkey Vero E6 cells and physiologically relevant human bronchial epithelial cells at safe therapeutic concentrations. Pixatimod also retained broad potency against variants of concern (VOC) including B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617.2 (Delta), and B.1.1.529 (Omicron). Furthermore, in a K18-hACE2 mouse model, pixatimod significantly reduced SARS-CoV-2 viral titers in the upper respiratory tract and virus-induced weight loss. This demonstration of potent anti-SARS-CoV-2 activity tolerant to emerging mutations establishes proof-of-concept for targeting the HS-Spike protein-ACE2 axis with synthetic HS mimetics and provides a strong rationale for clinical investigation of pixatimod as a potential multimodal therapeutic for COVID-19.
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| 2. |
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| 3. |
- Kalenga, T. M., et al.
(författare)
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Modified ent-Abietane Diterpenoids from the Leaves of Suregada zanzibariensis
- 2022
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Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 85:9, s. 2135-2141
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Tidskriftsartikel (refereegranskat)abstract
- The leaf extract of Suregada zanzibariensis gave two new modified ent-abietane diterpenoids, zanzibariolides A (1) and B (2), and two known triterpenoids, simiarenol (3) and fi-amyrin (4). The structures of the isolated compounds were elucidated based on NMR and MS data analysis. Single-crystal X-ray diffraction was used to establish the absolute configurations of compounds 1 and 2. The crude leaf extract inhibited the infectivity of herpes simplex virus 2 (HSV-2, IC50 11.5 mu g/mL) and showed toxicity on African green monkey kidney (GMK AH1) cells at CC50 52 mu g/ mL. The isolated compounds 1-3 showed no anti-HSV-2 activity and exhibited insignificant toxicity against GMK AH1 cells at >= 100 mu M.
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| 4. |
- Kiganda, Ivan, et al.
(författare)
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Antiviral Rotenoids and Isoflavones Isolated from Millettia oblata ssp. teitensis
- 2023
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Ingår i: Journal of Natural Products. - 0163-3864 .- 1520-6025. ; 87:4, s. 1003-1012
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Tidskriftsartikel (refereegranskat)abstract
- Three new (1-3) and six known rotenoids (5-10), along with three known isoflavones (11-13), were isolated from the leaves of Millettia oblata ssp. teitensis. A new glycosylated isoflavone (4), four known isoflavones (14-18), and one known chalcone (19) were isolated from the root wood extract of the same plant. The structures were elucidated by NMR and mass spectrometric analyses. The absolute configuration of the chiral compounds was established by a comparison of experimental ECD and VCD data with those calculated for the possible stereoisomers. This is the first report on the use of VCD to assign the absolute configuration of rotenoids. The crude leaves and root wood extracts displayed anti-RSV (human respiratory syncytial virus) activity with IC50 values of 0.7 and 3.4 μg/mL, respectively. Compounds 6, 8, 10, 11, and 14 showed anti-RSV activity with IC50 values of 0.4-10 μM, while compound 3 exhibited anti-HRV-2 (human rhinovirus 2) activity with an IC50 of 4.2 μM. Most of the compounds showed low cytotoxicity for laryngeal carcinoma (HEp-2) cells; however compounds 3, 11, and 14 exhibited low cytotoxicity also in primary lung fibroblasts. This is the first report on rotenoids showing antiviral activity against RSV and HRV viruses.
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| 5. |
- Lundin, Anna, et al.
(författare)
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Targeting Membrane-Bound Viral RNA Synthesis Reveals Potent Inhibition of Diverse Coronaviruses Including the Middle East Respiratory Syndrome Virus
- 2014
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Ingår i: Plos Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Coronaviruses raise serious concerns as emerging zoonotic viruses without specific antiviral drugs available. Here we screened a collection of 16671 diverse compounds for anti-human coronavirus 229E activity and identified an inhibitor, designated K22, that specifically targets membrane-bound coronaviral RNA synthesis. K22 exerts most potent antiviral activity after virus entry during an early step of the viral life cycle. Specifically, the formation of double membrane vesicles (DMVs), a hallmark of coronavirus replication, was greatly impaired upon K22 treatment accompanied by near-complete inhibition of viral RNA synthesis. K22-resistant viruses contained substitutions in non-structural protein 6 (nsp6), a membrane-spanning integral component of the viral replication complex implicated in DMV formation, corroborating that K22 targets membrane bound viral RNA synthesis. Besides K22 resistance, the nsp6 mutants induced a reduced number of DMVs, displayed decreased specific infectivity, while RNA synthesis was not affected. Importantly, K22 inhibits a broad range of coronaviruses, including Middle East respiratory syndrome coronavirus (MERS-CoV), and efficient inhibition was achieved in primary human epithelia cultures representing the entry port of human coronavirus infection. Collectively, this study proposes an evolutionary conserved step in the life cycle of positive-stranded RNA viruses, the recruitment of cellular membranes for viral replication, as vulnerable and, most importantly, druggable target for antiviral intervention. We expect this mode of action to serve as a paradigm for the development of potent antiviral drugs to combat many animal and human virus infections.
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| 6. |
- Mahambo, Emanuel T, et al.
(författare)
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Crotofolane Diterpenoids and Other Constituents Isolated from Croton kilwae.
- 2023
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Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 1520-6025 .- 0163-3864. ; 86:2, s. 380-389
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Tidskriftsartikel (refereegranskat)abstract
- Six new crotofolane diterpenoids (1-6) and 13 known compounds (7-19) were isolated from the MeOH-CH2Cl2 (1:1, v/v) extracts of the leaves and stem bark of Croton kilwae. The structures of the new compounds were elucidated by extensive analysis of spectroscopic and mass spectrometric data. The structure of crotokilwaepoxide A (1) was confirmed by single-crystal X-ray diffraction, allowing for the determination of its absolute configuration. The crude extracts and the isolated compounds were investigated for antiviral activity against respiratory syncytial virus (RSV) and human rhinovirus type-2 (HRV-2) in HEp-2 and HeLa cells, respectively, for antibacterial activity against the Gram-positive Bacillus subtilis and the Gram-negative Escherichia coli, and for antimalarial activity against the Plasmodium falciparum Dd2 strain. ent-3β,19-Dihydroxykaur-16-ene (7) and ayanin (16) displayed anti-RSV activities with IC50 values of 10.2 and 6.1 μM, respectively, while exhibiting only modest cytotoxic effects on HEp-2 cells that resulted in selectivity indices of 4.9 and 16.4. Compounds 2 and 5 exhibited modest anti-HRV-2 activity (IC50 of 44.6 μM for both compounds), while compound 16 inhibited HRV-2 with an IC50 value of 1.8 μM. Compounds 1-3 showed promising antiplasmodial activities (80-100% inhibition) at a 50 μM concentration.
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| 7. |
- Trybala, E, et al.
(författare)
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Interaction between pseudorabies virus and heparin/heparan sulfate : Pseudorabies virus mutants differ in their interaction with heparin/heparan sulfate when altered for specific glycoprotein C heparin-binding domain
- 1998
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Ingår i: Journal of Biological Chemistry. - : Elsevier BV. - 0021-9258 .- 1083-351X. ; 273:9, s. 5047-5052
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Tidskriftsartikel (refereegranskat)abstract
- Cell surface heparan sulfate serves as an initial receptor for a number of herpesviruses including pseudorabies virus (PrV). It has been demonstrated that the heparan sulfate-binding domain of PrV glycoprotein C is composed of three discrete clusters of basic residues corresponding to amino acids 76-RRKPPR-81, 96-HGRKR-100, and 133-RFYRRGRFR-141, respectively, and that these clusters are functionally redundant, i.e. each of them could independently support PrV attachment to cells (Flynn, S. J., and Ryan, P. (1996) J. Virol. 70, 1355-1364). To evaluate the functional significance of each of these clusters we have used PrV mutants in which, owing to specific alterations in glycoprotein C, the heparan sulfate-binding site is dominated by a single specific cluster. These mutants exhibited different patterns of susceptibility to selectively N-, 2-O-, and 6-O-desulfated heparin preparations in virus attachment/infectivity assay. Moreover PrV mutants differed as regard to efficiency of their attachment to and infection of cells pretreated with relatively low amounts of heparan sulfate-degrading enzymes. Furthermore glycoprotein C species, purified from respective mutants, bound heparin oligosaccharide fragments of different minimum size. These differences suggest that specific clusters of basic amino acids of the heparan sulfate-binding domain of glycoprotein C may support PrV binding to different structural features/stretches within the heparan sulfate chain.
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| 8. |
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| 9. |
- Trybala, E, et al.
(författare)
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Mode of Interaction Between Pseudorabies Virus and Heparan Sulfate/Heparin
- 1996
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Ingår i: Virology. - : Elsevier BV. - 0042-6822 .- 1096-0341. ; 218:1, s. 35-42
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Tidskriftsartikel (refereegranskat)abstract
- It has been demonstrated that the efficient attachment of pseudorabies virus (PrV) is mediated by an interaction between glycoprotein C (gC) and a cellular heparin-like substance (T. C. Mettenleiter, L. Zsak, F. Zuckermann, N. Sugg, H. Kern, and T. Ben-Porat, J. Virol. 64, 278–286, 1990). According to the prevalent concept, this interaction is likely to occur between clusters of basic residues of PrV gC and the negatively charged sulfate esters and carboxylate groups of heparan sulfate/heparin. To elucidate which of the three major types of sulfate groups of heparan sulfate/heparin are involved in the interaction with PrV, we used selectively N-, 2-O-, and 6-O-desulfated samples and other modified heparins as competitors in virus-attachment assays. PrV exhibited limited preference for the specific sulfate groups of heparan sulfate/heparin in accordance with a hierarchy of 6-O- > 2-O- >N-sulfates. In addition, since selective removal of any of the specific sulfates had only a slight effect on the competition capacity of heparin, it is likely that the combination of any two of three types of sulfate groups could contribute to an interaction with PrV with an efficiency nearly equal to native, fully sulfated heparin. When tested on different cell lines the pattern of PrV requirement for the specificO-sulfate groups, i.e., 6-O-sulfates > 2-O-sulfates, remained the same. However, different minimum lengths of heparin fragments were required to inhibit PrV attachment to different cell lines, suggesting a relative virus flexibility in accommodation to different forms of heparan sulfate.
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