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Chikungunya virus (CHIKV) causes a febrile disease associated with chronic arthralgia, which may progress to neurological impairment. Chikungunya fever (CF) is an ongoing public health problem in tropical and subtropical regions of the world, where control of the CHIKV vector, Aedes mosquitos, has failed. As there is no vaccine or specific treatment for CHIKV, patients receive only palliative care to alleviate pain and arthralgia. Thus, drug repurposing is necessary to identify antivirals against CHIKV. CHIKV RNA polymerase is similar to the orthologue enzyme of other positive-sense RNA viruses, such as members of the Flaviviridae family. Among the Flaviviridae, not only is hepatitis C virus RNA polymerase susceptible to sofosbuvir, a clinically approved nucleotide analogue, but so is dengue, Zika, and yellow fever virus replication. Here, we found that sofosbuvir was three times more selective in inhibiting CHIKV production in human hepatoma cells than ribavirin, a pan-antiviral drug. Although CHIKV replication in human induced pluripotent stem cell-derived astrocytes was less susceptible to sofosbuvir than were hepatoma cells, sofosbuvir nevertheless impaired virus production and cell death in a multiplicity of infection-dependent manner. Sofosbuvir also exhibited antiviral activity in vivo by preventing CHIKV-induced paw edema in adult mice at a dose of 20 mg/kg of body weight/day and prevented mortality in a neonate mouse model at 40- and 80-mg/kg/day doses. Our data demonstrate that a prototypic alphavirus, CHIKV, is also susceptible to sofosbuvir. As sofosbuvir is a clinically approved drug, our findings could pave the way to it becoming a therapeutic option against CF.

Chikungunya virus (CHIKV) causes a febrile disease associated with chronic arthralgia, which may progress to neurological impairment. Chikungunya fever (CF) is an ongoing public health problem in tropical and subtropical regions of the world, where control of the CHIKV vector, Aedes mosquitos, has failed. As there is no vaccine or specific treatment for CHIKV, patients receive only palliative care to alleviate pain and arthralgia. Thus, drug repurposing is necessary to identify antivirals against CHIKV. CHIKV RNA polymerase is similar to the orthologue enzyme of other positive-sense RNA viruses, such as members of the Flaviviridae family. Among the Flaviviridae, not only is hepatitis C virus RNA polymerase susceptible to sofosbuvir, a clinically approved nucleotide analogue, but so is dengue, Zika, and yellow fever virus replication. Here, we found that sofosbuvir was three times more selective in inhibiting CHIKV production in human hepatoma cells than ribavirin, a pan-antiviral drug. Although CHIKV replication in human induced pluripotent stem cell-derived astrocytes was less susceptible to sofosbuvir than were hepatoma cells, sofosbuvir nevertheless impaired virus production and cell death in a multiplicity of infection-dependent manner. Sofosbuvir also exhibited antiviral activity in vivo by preventing CHIKV-induced paw edema in adult mice at a dose of 20 mg/kg of body weight/day and prevented mortality in a neonate mouse model at 40- and 80-mg/kg/day doses. Our data demonstrate that a prototypic alphavirus, CHIKV, is also susceptible to sofosbuvir. As sofosbuvir is a clinically approved drug, our findings could pave the way to it becoming a therapeutic option against CF.

Scientific Reports 7: Article number: 40920; published online 18 January 2017; updated on 24 April 2017 The Competing Financial Interests section in this Article is incorrect and should read: “Dr. Karin Brüning is a member of the BMK consortium, able to produce sofosbuvir”.

Zika virus (ZIKV) is a member of the Flaviviridae family, along with other agents of clinical significance such as dengue (DENV) and hepatitis C (HCV) viruses. Since ZIKV causes neurological disorders during fetal development and in adulthood, antiviral drugs are necessary. Sofosbuvir is clinically approved for use against HCV and targets the protein that is most conserved among the members of the Flaviviridae family, the viral RNA polymerase. Indeed, we found that sofosbuvir inhibits ZIKV RNA polymerase, targeting conserved amino acid residues. Sofosbuvir inhibited ZIKV replication in different cellular systems, such as hepatoma (Huh-7) cells, neuroblastoma (SH-Sy5y) cells, neural stem cells (NSC) and brain organoids. In addition to the direct inhibition of the viral RNA polymerase, we observed that sofosbuvir also induced an increase in A-to-G mutations in the viral genome. Together, our data highlight a potential secondary use of sofosbuvir, an anti-HCV drug, against ZIKV.

Heterogeneous metallocene catalysts avoid reactor fouling in olefin polymerisations. For technical use the metallocene catalysts must be fixed on carriers. Silica is one of the favoured inorganic carriers. But the activities of heterogeneous metallocene catalysts on silica in ethylene and propylene polymerisation are often lower than those of comparable homogeneous catalyst systems. We tested the clay minerals kaolin and montmorillonite as inorganic carriers for the polymerisation of ethylene and propylene with commercially available titanocenes and zirconocenes and also with new types of titanocenes. The heterogeneous catalysts on kaolin were less active in ethylene polymerisation as comparable homogeneous catalysts and they were not active in propylene polymerisation. In contrast the heterogeneous catalysts on montmorillonite are often more active in ethylene or propylene polymerisation than comparable homogeneous systems. As cocatalysts trimethylaluminium (AlMe3, TMA) and triisobutylaluminium (Al(iBu3), TIBA) were used for heterogeneous polymerisations. As catalysts commercially available titanocenes and zirconocenes and also four titanocenes with unusual structures were tested which Lang et al. had synthesised. The high activities in ethylene or propylene polymerisations with montmorillonite may be due to the special structure of the montmorillonite carrier.

This review outlines the main issues concerning the production of antiretroviral (ARV) drugs in middle- and low-income countries and the relevant political, legal and technical requirements for supporting such production. The requirements for efficient local production, including the manufacture of generic and branded products and public demand, have been considered from economic, market and socio-political perspectives. A steady and consistent government policy is crucial to success. Additional crucial factors in establishing local production are adequate infrastructure, qualified human resources in technical and managerial areas, and production–distribution logistics systems. The creation or strengthening of a national drug regulatory agency is a basic requirement. Production of ARVs relies on the structure of the international market for active pharmaceutical ingredients (APIs), which are highly monopolized for inclusion in branded or patented drugs, or are concentrated in a few Asian generic companies. Countries seeking to begin local production must develop strategies to overcome the various barriers. For instance, sub-Saharan African countries may benefit from developing multilateral health agreements with neighbouring countries. Such agreements are recommended and should be complemented by technology transfers, especially for the manufacture of APIs. Achieving a production level that is sustainable in the long term is crucial to maintaining patients’ access to ARVs.

The cyclotetrasiloxane [(Me)(C6H4CH2NMe2-2)SiO]4 (2) can be synthesized by hydrolysis of the pentacoordinated silicon compounds (C6H4CH2NMe2-2)MeSiCl2 (1 )o r (C 6H4CH2NMe2-2)MeSi(OR)2 (3a ,R = CH2CHCH2; 3b ,R = CH2CCH) in quantitative yield. The solid-state structure of 2 is reported. Compound 2 crystallizes in the triclinic space group P-1 with the following cell parameters: a=9.575(2), b=15.018(3), c = 16.021(4) A ; = 94.72(12), = 90.96(2), = 103.75(2)°; V = 2228.5(9) A 3 and Z=2. Due to sterical hindrance the silicon atoms in 2 are tetra-coordinated, which differs from the starting materials 1, 3a and 3b, where hypervalent silicon centers exist. © 2001 Elsevier Science B.V. All rights reserved. Zusammenfassung

This article focuses on the preparation of water-soluble carbosiloxane dendrimers by the divergent growth method using repetitive hydrosilylation-alcoholysis cycles as well as ammonolysis and ionexchange reaction steps.

The preparation of the first-generation dendrimers Si(OCH 2 CH 2 CH 2 SiMe 2 OCH 2 CCH) 4 ( 5 ) as well as Si(OCH 2 CH 2 CH 2 SiMe 2 CCSiMe 3 ) 4 ( 7 ) from Si(OCH 2 CH 2 CH 2 SiMe 2 Cl) 4 ( 4 ) is described. While 5 can be synthesized by the reaction of 4 with HOCH 2 CCH ( 2 ) and NEt 3 in 80% yield, 7 is accessible by treatment of 4 with LiCCSiMe 3 ( 6 ) in 70% yield. When Si(OCH 2 CCH) 4 ( 3 ), 5 and 7 were reacted with four equivalents of Co 2 (CO) 8 ( 8 ), dendrimers Si(OCH 2 [(η 2 -CCH)Co 2 (CO) 6 ]) 4 ( 9 ), Si(OCH 2 CH 2 CH 2 SiMe 2 OCH 2 [(η 2 -CCH)Co 2 (CO) 6 ]) 4 ( 10 ) and Si(OCH 2 CH 2 CH 2 SiMe 2 [(η 2 -CCSiMe 3 )Co 2 (CO) 6 ]) 4 ( 11 ) were formed. These dendritic molecules possess as end-grafted entities hexacarbonyldicobalt-tetrahedrane fragments on their surface. Dendrimers 5 , 7 and 9 – 11 were fully characterized by elemental analysis, spectroscopic studies (IR, 1 H-, 13 C{ 1 H}-NMR) as well as gel-permeation chromatography.

The preparation of the first and second generation carbosiloxane dendrimers Si[OCH2- CH2CH2 SiMe(OCH2C=CH)2]4 (3) and Si{OCH2H2CH2SiMe[OCH2CH2CH2SiMe(OCH2 - C=CH)2]2}4 (5) by the reaction o f Si(OCH2CH2CH2SiMeCl2)4 (1) or Si[OCH2CH2CH2SiMe- (OCH2CH2CH2SiMeCl2)2]4 (4) with HOCH2C =CH (2) in the presence o f NEt3 is described. Dendrimers 3 and 5 contain propargyloxy units as terminal groups, which can be transferred to Co2((CO)8 (6) to give the hexacarbonyldicobalt functionalized dendritic molecules Si{OCH2CH2CH2[(η-OCH2C=CH)CO2(CO)6]2}4 (7) and Si{OCH2CH2CH2SiMe-(OCH2CH2CH2SiMe[(η-OCH2C=CH)CO2(CO)6]2)2}4 (8). All compounds were characterized by elemental analyses, spectroscopic studies (IR,1H-, 13C{1H }-, 29Si{1H} NMR) as well as GPC investigations

The divergent synthesis of the second generation carbosiloxane dendrimer Si(OCH 2 CH 2 CH 2 SiMe(OCH 2 CH 2 CH 2 SiMe(OCH 2 CHCH 2 ) 2 ) 2 ) 4 ( 5 ) is described. Hydrosilation of Si(OCH 2 CHCH 2 ) 4 ( 1 ) with HSiMeCl 2 in the presence of catalytic amounts of H 2 PtCl 6 produces Si(OCH 2 CH 2 CH 2 SiMeCl 2 ) 4 ( 2 ) in high yield. Treatment of 2 with HOCH 2 CHCH 2 and NEt 3 affords Si(OCH 2 CH 2 CH 2 SiMe(OCH 2 CHCH 2 ) 2 ) 4 ( 3 ). The sequential reaction of the latter molecule with HSiMeCl 2 /H 2 PtCl 6 and HOCH 2 CHCH 2 /NEt 3 affords the dendrimer 5 , which can be further functionalized with organometallic building blocks via hydrosilation reactions.