RESUMO
ß-D-3'-Azido-2',3'-dideoxyguanosine (3'-azido-ddG) is a potent inhibitor of HIV-1 replication with a superior resistance profile to zidovudine. Recently, we identified five novel 6-modified-3'-azido-ddG analogs that exhibit similar or superior anti-HIV-1 activity compared to 3'-azido-ddG in primary cells. To gain insight into their structure-activity-resistance relationships, we synthesized their triphosphate (TP) forms and assessed their ability to inhibit HIV-1 reverse transcriptase (RT). Steady-state and pre-steady-state kinetic experiments show that the 6-modified-3'-azido-ddGTP analogs act as adenosine rather than guanosine mimetics in DNA synthesis reactions. The order of potency of the TP analogs against wild-type RT was: 3'-azido-2,6-diaminopurine >3'-azido-6-chloropurine; 3'-azido-6-N-allylaminopurine > 2-amino-6-N,N-dimethylaminopurine; 2-amino-6-methoxypurine. Molecular modeling studies reveal unique hydrogen-bonding interactions between the nucleotide analogs and the template thymine base in the active site of RT. Surprisingly, the structure-activity relationship of the analogs differed in HIV-1 RT ATP-mediated excision assays of their monophosphate forms, suggesting that it may be possible to rationally design a modified base analog that is efficiently incorporated by RT but serves as a poor substrate for ATP-mediated excision reactions. Overall, these studies identify a promising strategy to design novel nucleoside analogs that exert profound antiviral activity against both WT and drug-resistant HIV-1.
Assuntos
Fármacos Anti-HIV/química , Didesoxinucleosídeos/química , Didesoxinucleotídeos/química , Transcriptase Reversa do HIV/química , Inibidores da Transcriptase Reversa/química , Adenosina/análogos & derivados , Trifosfato de Adenosina/química , Fármacos Anti-HIV/metabolismo , Domínio Catalítico , Didesoxinucleotídeos/metabolismo , Transcriptase Reversa do HIV/genética , Transcriptase Reversa do HIV/metabolismo , Modelos Moleculares , Mimetismo Molecular , Mutação , Inibidores da Transcriptase Reversa/metabolismoRESUMO
As a rapidly growing family of 2D transition metal carbides and nitrides, MXenes are recognized as promising materials for the development of future electronics and optoelectronics. So far, the reported patterning methods for MXene films lack efficiency, resolution, and compatibility, resulting in limited device integration and performance. Here, a high-performance MXene image sensor array fabricated by a wafer-scale combination patterning method of an MXene film is reported. This method combines MXene centrifugation, spin-coating, photolithography, and dry-etching and is highly compatible with mainstream semiconductor processing, with a resolution up to 2 µm, which is at least 100 times higher than other large-area patterning methods reported previously. As a result, a high-density integrated array of 1024-pixel Ti3 C2 Tx /Si photodetectors with a detectivity of 7.73 × 1014 Jones and a light-dark current ratio (Ilight /Idark ) of 6.22 × 106 , which is the ultrahigh value among all reported MXene-based photodetectors, is fabricated. This patterning technique paves a way for large-scale high-performance MXetronics compatible with mainstream semiconductor processes.
RESUMO
We recently reported that HIV-1 resistant to 3'-azido-3'-deoxythymidine (AZT) is not cross-resistant to 3'-azido-2',3'-dideoxypurines. This finding suggested that the nucleoside base is a major determinant of HIV-1 resistance to nucleoside analogs. To further explore this hypothesis, we conducted in vitro selection experiments by serial passage of HIV-1(LAI) in MT-2 cells in increasing concentrations of 3'-azido-2',3'-dideoxyguanosine (3'-azido-ddG), 3'-azido-2',3'-dideoxycytidine (3'-azido-ddC), or 3'-azido-2',3'-dideoxyadenosine (3'-azido-ddA). 3'-Azido-ddG selected for virus that was 5.3-fold resistant to 3'-azido-ddG compared to wild-type HIV-1(LAI) passaged in the absence of drug. Population sequencing of the entire reverse transcriptase (RT) gene identified L74V, F77L, and L214F mutations in the polymerase domain and K476N and V518I mutations in the RNase H domain. However, when introduced into HIV-1 by site-directed mutagenesis, these 5 mutations only conferred â¼2.0-fold resistance. Single-genome sequencing analyses of the selected virus revealed a complex population of mutants that all contained L74V and L214F linked to other mutations, including ones not identified during population sequencing. Recombinant HIV-1 clones containing RT derived from single sequences exhibited 3.2- to 4.0-fold 3'-azido-ddG resistance. In contrast to 3'-azido-ddG, 3'-azido-ddC selected for the V75I mutation in HIV-1 RT that conferred 5.9-fold resistance, compared to the wild-type virus. Interestingly, we were unable to select HIV-1 that was resistant to 3'-azido-ddA, even at concentrations of 3'-azido-ddA that yielded high intracellular levels of 3'-azido-ddA-5'-triphosphate. Taken together, these findings show that the nucleoside base is a major determinant of HIV-1 resistance mechanisms that can be exploited in the design of novel nucleoside RT inhibitors.
Assuntos
Fármacos Anti-HIV/farmacologia , Didesoxinucleosídeos/farmacologia , Transcriptase Reversa do HIV/antagonistas & inibidores , HIV-1/efeitos dos fármacos , Inibidores da Transcriptase Reversa/farmacologia , Azidas/farmacologia , Sequência de Bases , Didesoxiadenosina/análogos & derivados , Didesoxiadenosina/farmacologia , Farmacorresistência Viral , Transcriptase Reversa do HIV/metabolismo , HIV-1/genética , Mutagênese Sítio-Dirigida , Análise de Sequência de RNA , Zalcitabina/análogos & derivados , Zalcitabina/farmacologia , Zidovudina/farmacologiaRESUMO
Based on the anti-hepatitis C activity of 2'-C-methyl-adenosine and 2'-C-methyl-guanosine, a series of new modified purine 2'-C-methyl nucleosides was prepared as potential anti-hepatitis C virus agents. Herein, we report the synthesis of both 6-modified and 2-modified purine 2'-C-methyl-nucleosides along with their anti-HCV replication activity and cytotoxicity in different cells.
Assuntos
Antivirais/química , Antivirais/farmacologia , Hepacivirus/efeitos dos fármacos , Nucleosídeos de Purina/química , Nucleosídeos de Purina/farmacologia , Animais , Antivirais/síntese química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Hepatite C/tratamento farmacológico , Humanos , Nucleosídeos de Purina/síntese químicaRESUMO
Based on the promising drug resistance profile and potent anti-HIV activity of beta-d-3'-azido-2',3'-dideoxyguanosine, a series of purine modified nucleosides were synthesized by a chemical transglycosylation reaction and evaluated for their antiviral activity, cytotoxicity, and intracellular metabolism. Among the synthesized compounds, several show potent and selective anti-HIV activity in primary lymphocytes.
Assuntos
Fármacos Anti-HIV/síntese química , Didesoxinucleosídeos/síntese química , Transcriptase Reversa do HIV/antagonistas & inibidores , Fármacos Anti-HIV/química , Fármacos Anti-HIV/toxicidade , Didesoxinucleosídeos/química , Didesoxinucleosídeos/toxicidade , Glicosilação , Transcriptase Reversa do HIV/metabolismo , Humanos , Linfócitos/efeitos dos fármacos , Linfócitos/imunologiaRESUMO
The conversion of selected ß-D-2,6-diaminopurine nucleosides (DAPNs) to their phosphoramidate prodrug (PD) substantially blocks the conversion to the G-analog allowing for the generation of two bioactive nucleoside triphosphates (NTPs) in human hepatocytes. A variety of 2'-C-methyl DAPN-PDs were prepared and evaluated for inhibition of HCV viral replication in Huh-7 cells, cytotoxicity in various cell lines, and cellular pharmacology in both Huh-7 and primary human liver cells. The DAPN-PDs were pan-genotypic, effective against various HCV resistant mutants, and resistant variants could not be selected. 2'-C-Me-DAPN-TP and 2'-C-Me-GTP were chain terminators for genotype 1b HCV-pol, and single nucleotide incorporation assays revealed that 2'-C-Me-DAPN-TP was incorporated opposite U. No cytotoxicity was observed with our DAPN-PD when tested up to 50 µM. A novel, DAPN-PD, 15c, has been selected for further evaluation because of its good virologic and toxicologic profile and its ability to deliver two active metabolites, potentially simplifying HCV treatment.
Assuntos
2-Aminopurina/análogos & derivados , Antivirais/química , Antivirais/farmacologia , Guanosina Trifosfato/química , Guanosina Trifosfato/farmacologia , Hepacivirus/efeitos dos fármacos , 2-Aminopurina/química , 2-Aminopurina/metabolismo , 2-Aminopurina/farmacologia , Amidas/química , Amidas/metabolismo , Amidas/farmacologia , Antivirais/metabolismo , Linhagem Celular , Células Cultivadas , Guanosina Trifosfato/metabolismo , Hepacivirus/genética , Hepatite C/tratamento farmacológico , Humanos , Metilação , Ácidos Fosfóricos/química , Ácidos Fosfóricos/metabolismo , Ácidos Fosfóricos/farmacologia , Pró-Fármacos/química , Pró-Fármacos/metabolismo , Pró-Fármacos/farmacologia , Ribonucleosídeos/química , Ribonucleosídeos/metabolismo , Ribonucleosídeos/farmacologiaRESUMO
A series of hitherto unknown 3'-α-[1,2,3]-substituted triazolo-2',3'-dideoxypyrimidine nucleoside analogues of the anti-HIV 3'-azido-3'-deoxythymidine (AZT) were synthesized through catalyzed alkyne-azide 1,3-dipolar cycloaddition (Huisgen reaction). Those 3'-[1,2,3]-triazolo analogues bearing an azido alkyl chain were evaluated for their anti-HIV activity against HIV-1 in primary human lymphocytes as well as for their cytotoxicity in different cells. None of them inhibit HIV replication (EC(50) > 20 µM); two of them were converted to their triphosphate form to evaluate their HIV-RT inhibition.
Assuntos
Fármacos Anti-HIV/síntese química , Fármacos Anti-HIV/farmacologia , HIV-1/efeitos dos fármacos , Nucleosídeos/síntese química , Nucleosídeos/farmacologia , Triazóis/química , Animais , Fármacos Anti-HIV/química , Fármacos Anti-HIV/toxicidade , Azidas/química , Linhagem Celular , Transcriptase Reversa do HIV/antagonistas & inibidores , HIV-1/enzimologia , Humanos , Nucleosídeos/química , Nucleosídeos/toxicidade , Relação Estrutura-AtividadeRESUMO
Microwave-assisted optimized transglycosylation reactions were used to prepare eleven modified l-3'-azido-2',3'-dideoxypurine nucleosides. These l-nucleoside analogs were evaluated against HIV and hepatitis B virus. The l-3'-azido-2',3'-dideoxypurines nucleosides were metabolized to nucleoside 5'-triphosphates in primary human lymphocytes, but exhibited weak or no antiviral activity against HIV-1. The nucleosides were also inactive against HBV in HepG2 cells. Pre-steady state kinetic experiments demonstrated that the l-3'-azido-2',3'-dideoxypurine triphosphates could be incorporated by purified HIV-1 reverse transcriptase, although their catalytic efficiency (k(pol)/K(d)) of incorporation was low. Interestingly, a phosphoramidate prodrug of l-3'-azido-2',3'-dideoxyadenosine exhibited anti-HIV-1 activity without significant toxicity.
Assuntos
Antivirais/síntese química , Antivirais/farmacologia , Nucleosídeos/síntese química , Nucleosídeos/farmacologia , Linhagem Celular , Glicosilação , HIV-1/efeitos dos fármacos , Vírus da Hepatite B/efeitos dos fármacos , Humanos , Cinética , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Micro-Ondas , Modelos Moleculares , Inibidores da Transcriptase Reversa/síntese química , Inibidores da Transcriptase Reversa/farmacologia , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
A new efficient synthesis of (2S,3R)-3-hydroxy-3-methylproline (3) is reported. During the course of a recent study on the Lewis acid promoted intramolecular opening of an epoxide by a carbamate NH, a highly concerted rearrangement was unexpectedly observed. Further investigations of substrate generality show that delta-carbamate-alpha,beta-epoxide esters commonly underwent similar rearrangements with the aid of Lewis acids. Retrosynthetic analysis of such a C(2)-N disconnection can lead to an efficient synthesis of (2S,3R)-3-hydroxy-3-methylproline (3) in high enantio purity. Stereochemistries were established by a Sharpless asymmetric dihydroxylation and a diastereoselective reductive amination.