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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

RNA plays a pivotal role in the replication of all organisms, including viral and bacterial pathogens. The development of small molecules that selectively interfere with undesired RNA activity is a promising new direction for drug design. Currently, there are no anti-HIV treatments that target nucleic acids. This article presents the HIV-1 Rev response element (RRE) as an important focus for the development of antiviral agents that target RNA. The Rev binding site on the RRE is highly conserved, even between different groups of HIV-1 isolates. Compounds that inhibit HIV replication by binding to the RRE and displacing Rev are therefore expected to retain activity across groups of genetically diverse HIV infections. Systematic evaluations of both the RRE affinity and specificity of numerous small molecule inhibitors are essential for deciphering the parameters that govern effective RRE recognition. This article discusses fluorescence-based techniques that are useful for probing a small molecule's RRE affinity and its ability to inhibit Rev-RRE binding. Rev displacement experiments can be conducted by observing the fluorescence anisotropy of a fluorescein-labeled Rev peptide, or by quantifying its displacement from a solid-phase immobilized RRE. Experiments conducted in the presence of competing nucleic acids are useful for evaluating the RRE specificity of Rev-RRE inhibitors. The discovery and characterization of new RRE ligands are described. Eilatin is a polycyclic aromatic heterocycle that has at least one binding site on the RRE (apparent Kd is approximately 0.13 microM), but it does not displace Rev upon binding the RRE (IC50 > 3 microM). In contrast, ethidium bromide and two eilatin-containing metal complexes show better consistency between their RRE affinity and their ability to displace a fluorescent Rev peptide from the RRE. These results highlight the importance of conducting orthogonal binding assays that establish both the RNA affinity of a small molecule and its ability to inhibit the function of the RNA target. Some Rev-RRE inhibitors, including ethidium bromide, Lambda-[Ru(bpy)(2)eilatin]2+, and Delta-[Ru(bpy)(2)eilatin]2+ also inhibit HIV-1 gene expression in cell cultures (IC50 = 0.2-3 microM). These (and similar) results should facilitate the future discovery and implementation of anti-HIV drugs that are targeted to viral RNA sites. In addition, a deeper general understanding of RNA-small molecule recognition will assist in the effective targeting of other therapeutically important RNA sites.
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PMID:Fluorescence-based methods for evaluating the RNA affinity and specificity of HIV-1 Rev-RRE inhibitors. 1292 96

In the present study, a series of 6-bromo-2,3-disubstitued-4(3H)-quinazolinones was synthesized by condensation of 6-bromo-2-substituted-benzoxazin-4-one with trimethoprim, pyrimethamine and lamotrigine. The chemical structures of the synthesized compounds were confirmed by means of IR, (1)H-NMR and mass spectral and elemental analysis. The antiviral activity and cytotoxicity of the compounds were tested in E(6)SM (Herpes simplex-1 KOS, Herpes simplex-1 TK-KOS ACV, Herpes simplex-2 G, Vaccinia virus, Vesicular stomatitis virus, Parainfluenza-3 virus, Reovirus-1, Sindbis virus, Coxsackie virus B4 and Punta Toro virus) and HeLa cell culture (Vesicular stomatitis virus, Coxsackie virus B4 and Respiratory syncyticla virus). Investigation of anti-HIV activity was done against replication of HIV-1 (HTLV-III B LAI) in MT-4 cells. 6-Bromo-2-phenyl-3-[(4-amino-5-(4-chlorophenyl)-6-ethylpyrimidin-2-yl]-4(3H)-quinazolinone (4) exhibited the most potent antiviral activity with a MIC of 1.92 microg/ml against vaccinia virus in E(6)SM cell culture. The other compounds did not exhibit antiviral activity nor afford significant cytoprotection to the E(6)SM and HeLa cell culture when challenged with the viruses. The study implies that 4 may possess activity against Pox viruses including variola. In the anti-HIV study, 6-bromo-2-methyl-3-[(4-amino-5-(4-chlorophenyl)-6-ethylpyrimidin-2-yl]-4(3H)-quinazolinone (3) and 6-bromo-2-phenyl-3-[(4-amino-5-(4-chlorophenyl)-6-ethylpyrimidin-2-yl]-4(3H)-quinazolinone (4) exhibited the least cytotoxic concentration (0.424, 0.461 microg/ml) which is an index of the infective viability of mock infected MT-4 cells with HIV-1. None of the compounds exhibited significant anti-HIV activity.
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PMID:Synthesis, antiviral and cytotoxic activity of 6-bromo-2,3-disubstituted-4(3H)-quinazolinones. 1295 71

Eilatin-containing ruthenium complexes bind to a broad range of different nucleic acids including: calf thymus (CT) DNA, tRNA(Phe), polymeric RNAs and DNAs, and viral RNAs including the HIV-1 RRE and TAR. The nucleic acid specificity of Lambda- and Delta-[Ru(bpy)2eilatin]2+ have been compared to that of the 'free' eilatin ligand, and to the classic intercalating agent ethidium bromide. Interestingly, all four compounds appear to bind to nucleic acids by intercalation, but the trends in nucleic acid binding specificity are highly diverse. Unlike ethidium bromide, both eilatin and the eilatin-containing coordination complexes bind to certain single-stranded RNAs with high affinity (K(d) < or = 1 microM). Eilatin itself is selective for electron-poor polymeric purines, while the eilatin-coordination complexes exhibit preference for the polypyrimidine r(U). These results show how the binding specificity of an intercalating ligand can change upon its incorporation into an octahedral metal complex.
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PMID:The DNA and RNA specificity of eilatin Ru(II) complexes as compared to eilatin and ethidium bromide. 1450 Aug 37

Semisynthetic aminoglycoside derivatives may provide a means to selectively target viral RNA sites, including the HIV-1 Rev response element (RRE). The design, synthesis, and evaluation of derivatives based upon neomycin B, kanamycin A, and tobramycin conjugates of 9-aminoacridine are presented. To evaluate the importance of the acridine moiety, a series of dimeric aminoglycosides as well as unmodified "monomeric" aminoglycosides have also been evaluated for their nucleic acid affinity and specificity. Fluorescence-based binding assays that use ethidium bromide or Rev peptide displacement are used to quantify the affinities of these compounds to various nucleic acids, including the RRE, tRNA, and duplex DNA. All the modified aminoglycosides exhibit a high affinity for the Rev binding site on the RRE (K(d) <or= 10 nM), but few compounds have a high specificity for the RRE. Compared to the acridine conjugates, the dimeric and unmodified aminoglycosides exhibit good RNA over DNA selectivity, but show little differentiation between different RNA molecules. Neomycin-based derivatives consistently have the highest RNA and DNA affinities, but the lowest RRE specificity. To optimize these derivatives for RRE specificity, a series of neomycin-acridine conjugates with variable linker lengths were synthesized and evaluated. The neo-acridine conjugate with the shortest linker length has the optimal RRE specificity. Duplex DNA, on the other hand, prefers the acridine conjugate with the longest linker length, and duplex RNA (poly r[A]-r[U]) has the highest affinity for the conjugate with an intermediate linker length. Compared to neomycin B, the derivatives based upon tobramycin and kanamycin A have slightly lower RRE affinities, but better RRE specificities. These results illustrate how the binding affinity and specificity of aminoglycoside intercalator conjugates can be tuned by optimizing the linker length and by changing the identity of the aminoglycoside moiety. These results also indicate that many aminoglycoside-based ligands are capable of high-affinity binding of RNA, but achieving high site specificity remains a challenging objective.
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PMID:RNA-ligand interactions: affinity and specificity of aminoglycoside dimers and acridine conjugates to the HIV-1 Rev response element. 1451 90

A series of substituted phenanthridine derivatives has been synthesized by converting the amines at the 3- and 8-positions of ethidium bromide into guanidine, pyrrole, urea, and various substituted ureas. The resulting derivatives exhibit unique spectral properties that change upon binding nucleic acids. The compounds were analyzed for their ability to inhibit the HIV-1 Rev-Rev Response Element (RRE) interaction, as well as for their affinity to calf thymus DNA. One derivative (3,8-bis-urea-ethylenediamine-5-ethyl-6-phenylphenanthridinium trifuroracetate) has an enhanced affinity and specificity for HIV-1 RRE as compared to ethidium bromide. These results indicate that the nucleic acid affinity and specificity of an intercalating agent can be tuned by synthetic modification of its exocyclic amines.
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PMID:Synthesis, photophysical properties, and nucleic acid binding of phenanthridinium derivatives based on ethidium. 1460 88

Investigation into the mechanism of action of vaccine adjuvants provides opportunities to define basic immune principles underlying the induction of strong immune responses and insights useful for the rational development of subunit vaccines. A novel HIV vaccine composed of plasmid DNA-encoding p55 gag formulated with poly-lactide-co-glycolide microparticles (PLG) and cetyl trimethyl ammonium bromide (CTAB) elicits both serum antibody titers and cytotoxic lymphocyte activity in mice at doses two orders of magnitude lower than those required for comparable response to plasmid DNA in saline. Using this model, we demonstrated the increase in potency requires the DNA to be complexed to the PLG-CTAB microparticles. Furthermore, the PLG-CTAB-DNA formulation increased the persistence of DNA at the injection site, recruited mononuclear phagocytes to the site of injection, and activated a population of antigen presenting cells. Intramuscular immunization with the PLG-CTAB-DNA complex induced antigen expression at both the injection site and the draining lymph node. These findings demonstrate that the PLG-CTAB-DNA formulation exhibits multiple mechanisms of immunopotentiation.
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PMID:Mechanisms of increased immunogenicity for DNA-based vaccines adsorbed onto cationic microparticles. 1464

A novel carboacyclic nucleoside analogue, 9-[2-bromo-4-hydroxy-3-hydroxymethyl-2-butenyl] adenine, and its derivatives were designed and synthesized as open-chain analogues of neplanocin A. The syntheses were accomplished via the coupling of adenine or pyrimidine bases to the key intermediate allylic bromide 7. The bromide 7 was prepared from epichlorohydrin in a seven step process in a 54% overall yield. The synthesized compounds were evaluated for their antiviral activity against the polio virus, HSV and HIV.
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PMID:Synthesis of novel carboacyclic nucleosides with vinyl bromide moiety as open-chain analogues of neplanocin A. 1472 29

The conjugation of the protein transduction domain (PTD) from the HIV-1 Tat protein to shell cross-linked (SCK) nanoparticles is a method to facilitate cell surface binding and transduction. In the previous report, the preparation, derivatization, and characterization of peptide-functionalized SCK nanoparticles were reported in detail. Following assembly, the constructs were evaluated in vitro and in vivo to obtain a preliminary biocompatibility assessment. The effects of SCK exposure on cell viability were evaluated using a metabolic 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and a fluorescent apoptosis assay. Furthermore, stages of apoptosis were quantified by flow cytometry. Although higher levels of peptide functionalization resulted in decreased metabolic function as measured by MTT assay, significant apoptosis was not observed below 500 mg/L for all the samples. To evaluate the potential immunogenic response of the peptide-derivatized constructs, a real-time polymerase chain reaction (RT-PCR) system that allows for the in vitro analysis and quantification of the cellular inflammatory responses tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL1-beta) was utilized. The inflammatory response to the peptide-functionalized SCK nanoparticles as measured by RT-PCR show statistically significant increases in the levels of both TNF-alpha and IL1-beta relative to tissue culture polystyrene (TCPS). However, the measured cytokine levels did not preclude the further testing of SCKs in an in vivo mouse immunization protocol. In this limited assay, measured increases in immunoglobulin G (IgG) concentration in the sera were minimal with no specific interactions being isolated, and more importantly, none of the mice (>50) subjected to the three 100 microg immunization protocol have died. Additionally, no gross morphological changes were observed in postmortem organ histology examinations.
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PMID:Peptide-derivatized shell-cross-linked nanoparticles. 2. Biocompatibility evaluation. 1526 57

An efficient procedure has been developed for the synthesis of 3'-fluoro-2',3'-dideoxy-2',3'-didehydro-4'-ethynyl D- and L-furanosyl nucleosides (1 and 2) starting from 2,3-O-isopropylidene-d-glyceraldehyde. The key intermediate 1-O-benzoyl-3E-fluoro-3,4-unsaturated-5,6-di(tert-butyldimethylsilyloxy)-2-hexanone 8 was obtained in nine steps with the overall yield of 22%. The alpha,beta-unsaturated ketone 8 was then treated with ethynylmagnesium bromide in a typical Grignard reaction procedure to afford the two intermediates 9 and 10, which after deprotection, oxidation, and acetylation gave the corresponding 4-ethynyl-substituted D- and L-sugar moieties 15 and 16, respectively. A series of D- and L-pyrimidine and purine nucleosides were prepared by the coupling of the sugar moieties with various silylprotected bases. The anomeric mixtures were obtained after condensation. After separation, the beta-isomers were further deprotected to yield the target nucleosides. All the newly synthesized 4'-substituted nucleosides were tested for their activities against HIV, among which the D-adenine derivative showed moderate anti-HIV activity (EC(50) = 25.1 microM) without significant cytotoxicity.
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PMID:Synthesis of 3'-fluoro-2',3'-dideoxy-2',3'-didehydro-4'-ethynyl-D- and -L-furanosyl nucleosides. 1537 88

Novel 2',3',4'-triply branched carbocyclic nucleosides were synthesized in this study. The introduction of two methyl groups in the 2'- and 3'-position was accomplished by a Horner-Wadsworth-Emmons reaction and isopropenyl magnesium bromide addition, respectively. The construction of the required 4'-quaternary carbon was carried out using a [3,3]-sigmatropic rearrangement. Bis-vinyls were successfully cyclized using a Grubbs' catalyst II. The natural bases (adenine, cytosine) were efficiently coupled using a Pd(0) catalyst. The antiviral activities of the synthesized compounds were evaluated against HIV-1, HSV-1, HSV-2 and HCMV. Compound 30 displayed moderate anti-HCMV activity (EC50 = 30.1 microg/mL), without exhibiting any cytotoxicity at up to 100 microM.
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PMID:Synthesis and biological evaluation of novel 2',3',4'-triply branched carbocyclic nucleosides as potential antiviral agents. 1554 Feb 23


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