Anti-HIV-1 and HIV-2 activity of naphthalenedisulfonic acid derivatives. Inhibition of cytopathogenesis, giant cell formation, and reverse transcriptase activity

Anionic Liposomes Inhibit Human Immunodeficiency Virus Type 1 (HIV-1) Infectivity in CD4+ A3.01 and H9 Cells

Immunodeficiency viruses undergo fusion with liposomes containing anionic phospholipids (Larsen etal., 1990). We have investigated the effect of liposomes composed of cardiolipin, phosphatidylserine or phosphatidylinositol, on the infectivity of three strains of HIV-1 in A3.01 and H9 cells, measured by p24 (gag) production in the medium. The infectivity of HIV-1 in A3.01 or H9 cells was inhibited by the presence of cardiolipin liposomes during a 2 h infection period, with IC50's of 23.0, 4.8, and 5.0 μM phospholipid, respectively, for the different strains. Liposomes composed of phosphatidylserine or phosphatidylinositol were ineffective under similar conditions. However, prolonged pre-incubation of the virus with these liposomes also inhibited infectivity. Inhibition of virus binding to cells could not account for the inhibition of infectivity. We propose that the fusion products of HIV-1 and anionic liposomes are impaired in their ability to fuse with the plasma membrane.

Naphthalenesulphonic Acid Derivatives as Potential anti-HIV-1 Agents. Chemistry, Biology and Molecular Modelling of Their Inhibition of Reverse Transcriptase

Activity against human immunodeficiency virus (HIV) in the naphthalenesulphonic acid series is most pronounced in the disulphonic acid series. In this class of compounds, N-acyl derivatives of 4-amino-5-hydroxy-2,7-naphthalenedisulphonic acid demonstrate significant anti-HIV activity at non-toxic doses. The most potent compounds in this group of agents are bis naphthalenedisulphonic acids. A bis derivative containing a decamethylene spacer demonstrated activity against HIV-1, HIV-2 giant cell formation and reverse transcriptase (RT). This compound also demonstrated an in vitro therapeutic index (ratio of 50% cytotoxic concentration to 50% inhibitory antiviral concentration) of 10.6. Molecular modelling analyses of this agent, suramin, and several suramin analogues were undertaken to explain the potent anti-HIV-1 RT activity. These studies were carried out using the molecular decomposition/recomposition strategy, conformational searching, energy minimization and molecular dynamics (MD) simulation. The bis naphthalenedisulphonic acid derivative compound 1, having a flexible decamethylene spacer, was shown to be able to mimic the helical twist of the B-DNA backbone as a low energy conformer state.

Selective Inhibition of Myxovirus Replication by a Novel Series of Cholesterol-Naphthalenesulfonic Acid Hybrid Molecules

A novel series of hybrid molecules with cholesterol and naphthalenesulfonic acid have been synthesized and evaluated for their inhibitory activity against myxoviruses (respiratory syncytial virus [RSV], influenza A and B virus), Naphthalenesulfonic acids (compounds 1–3) and cholesterols (compounds 4 and 5) did not inhibit myxovirus-induced cytopathic-ity. However, hybrid molecules (compounds 6 and 7) proved active against RSV and influenza A virus but not influenza B virus. The antiviral effects of the hybrid compounds 6 and 7 were comparable to those of dextran sulfate. Mixtures of naphthalenesulfonic acid and cholesteryl chloroformate (compounds 1 and 5 molecules, corresponding to the hybrid molecule 6; and compounds 2 and 5, corresponding to the hybrid molecule 7) did not show antiviral activity. The mode of action of the cholesterol-linked naphthalenesulfonic acids can be attributed to inhibition of virus-cell fusion (influenza A virus) or inhibition of both virus-cell binding and fusion (RSV).

Inhibition of HIV-1-Induced Cytopathogenicity, Syncytium Formation, and Virus-Cell Binding by Naphthalenedisulphonic Acids through Interaction with the Viral Envelope gp120 Glycoprotein

Bis-naphthalenedisulphonic acid derivatives with a biphenyl spacer, 4,4′-[4,4′-biphenyldiylbis(sulphonyl-amino)]bis(5-hydroxy-2,7-naphthalenedisulphonic acid) and 3,3′-[4,4′-biphenyldiylbis(sulphonyl-amino)]bis(1,5-naphthalenedisulphonic acid), have previously been reported as potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) replication in cell culture. These compounds have also proved inhibitory to syncytium formation in cocultures of MOLT-4 cells with HIV-1-infected HUT-78 cells. They also inhibit the binding of HIV-1 virions to MT-4 cells as determined by a flow cytometric (FACS) method. Further studies on their mechanism of action by the FACS have revealed that the compounds inhibit the binding of anti-gp120 monoclonal antibody to the viral envelope glycoprotein gp120. Binding of OKT4A/Leu3a monoclonal antibody to the cellular CD4 receptor is not affected by the compounds. These results suggest that the anti-HIV-1 activity of the naphthalenedisulphonic acid derivatives can be attributed to inhibition of the gp120-CD4 interaction through binding of the compounds to the viral gp120 antigen.

Novel furanylarylene arylsulfonylindolesulfonamides: synthesis and their antibacterial evaluation

An array of furanylarylene arylsulfonylindolesulfonamides was synthesized through multi-step synthetic protocols involving bromination, stannylation, Stille cross coupling, reduction, arylsulfonylation, chlorosulfonylation, and condensation reactions. As a preliminary evaluation, these analogs were tested for antibacterial activity against a series of bacterial strains such as Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae using a two-fold serial dilution assay. Whereas analogs possessing unsubstitution, bromosubstitution, or methyl substitution on the benzene ring of benzenesulfonyl group were less active/inactive, the methoxy and chloro substituted counterparts were demonstrated to be comparatively more active. A few of them were found to exhibit better activity than the standard, streptomycin against selective organisms.

Prevention of HIV-1 infection by platinum triazines

To identify and explore the activity of compounds which may act as anti-HIV virucidal agents, we have investigated platinum compounds, especially those containing N-donor aromatic ligands. After screening over 70 related agents, including N-donor aromatic ligands and metal precursors, we have identified a novel class of platinum(II) complexes with 2-pyridyl-1,2,4-triazine derivatives and Pt(II) formulations with these derivatives (ptt compounds) as having the highest anti-HIV activity. The maximum activity was observed when the agents were added immediately post-infection. The ptt agents did not block cell fusion activity of HIV-1 Env proteins in cells bearing CD4X4 or CD4R5 receptors, indicating a lack of interaction with the Env protein. The ptt compounds exhibit low toxicity for human epithelial cells, and are thus promising candidates for use as microbicides or antiviral agents against HIV.

Inhibition of human immunodeficiency virus replication by the sulfonated stilbene dye resobene

The anti-HIV sulfonated dye, resobene, was found to be a potent inhibitor of the attachment of HIV to target cells, the fusion of envelope- and CD4-expressing cells, and the cell-to-cell transmission of virus. Resobene inhibited the infection of phenotypically distinct, established human cell lines and fresh human peripheral blood lymphocytes and macrophages by laboratory-derived isolates of human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), and a panel of biologically diverse primary clinical isolates, including syncytium-inducing and non-syncytium-inducing viruses and strains representative of the various virus clades found worldwide. The compound was also active against all drug-resistant virus isolates tested. Cell-based and biochemical mechanism of action studies demonstrated that the compound inhibits the attachment of infectious virus and fusion of virus-infected cells to uninfected target cells by binding to the cationic V3 loop of the envelope glycoprotein. Resobene effectively inhibited the infection of cell populations which do and do not express cell surface CD4. Resobene prevented infection of the cervical epithelial cell line ME180, suggesting the compound may effectively act as a topical microbicide to prevent the sexual transmission of HIV.

Liposomal entrapment of suramin(II): interaction of suramin with phospholipids of various chain lengths

Previously, we reported that the entrapment of suramin in dipalmitoylphosphatidylcholine (DPPC, C16) multilamellar liposomes ranged from 25% to 65% and the addition of 30-50 mol% cholesterol (CHL) greatly reduced entrapment. Entrapment of small molecules similar to suramin, disodium 1,5-naphthalenedisulfonic acid (5.5%) and sodium 3-amino-2,7-naphthalenedisulfonic acid (1.2%), were very low. In the present study, the entrapment and interaction of suramin with dilauroylphosphatidylcholine (DLPC, C12), dimyristoylphosphatidylcholine (DMPC, C14), and distearoylphosphatidylcholine (DSPC, C18) liposomes was investigated. DLPC and DMPC showed 2-3-fold higher entrapment percentages (95.1% and 74.2%, respectively) than DPPC (37%). However, the entrapment with DSPC (29%) was about 25% lower than DPPC. Adding 50 mol% cholesterol greatly reduced suramin entrapment for all phospholipids. The entrapment of polysulfonated dyes such as Evans blue, Direct blue 1, or Trypan blue, which are structurally similar to suramin, was found to be in the same order of DLPC > DMPC > DPPC > DSPC. Differential scanning calorimetry of aqueous dispersions of DLPC and DMPC with suramin showed more apparent interaction than for DPPC and DSPC. These results suggest that a large portion of the associated suramin and other polysulfonated compounds results from binding to the surface of the phospholipid bilayer or intercalation into the liposomal bilayer. The phospholipid chain length effect on entrapment may be due to the lower net van der Waals interaction between hydrocarbon chains for shorter acyl chains which also increases the bilayer intermolecular spacing. Such effects could then increase the ability of suramin to interact with individual phospholipid molecules.

Antiviral therapy for human immunodeficiency virus infections

Depending on the stage of their intervention with the viral replicative cycle, human immunodeficiency virus inhibitors could be divided into the following groups: (i) adsorption inhibitors (i.e., CD4 constructs, polysulfates, polysulfonates, polycarboxylates, and polyoxometalates), (ii) fusion inhibitors (i.e., plant lectins, succinylated or aconitylated albumins, and betulinic acid derivatives), (iii) uncoating inhibitors (i.e., bicyclams), (iv) reverse transcription inhibitors acting either competitively with the substrate binding site (i.e., dideoxynucleoside analogs and acyclic nucleoside phosphonates) or allosterically with a nonsubstrate binding site (i.e., non-nucleoside reverse transcriptase inhibitors), (v) integration inhibitors, (vi) DNA replication inhibitors, (vii) transcription inhibitors (i.e., antisense oligodeoxynucleotides and Tat antagonists), (viii) translation inhibitors (i.e., antisense oligodeoxynucleotides and ribozymes), (ix) maturation inhibitors (i.e., protease inhibitors, myristoylation inhibitors, and glycosylation inhibitors), and finally, (x) budding (assembly/release) inhibitors. Current knowledge, including the therapeutic potential, of these various inhibitors is discussed. In view of their potential clinical the utility, the problem of virus-drug resistance and possible strategies to circumvent this problem are also addressed.

Liposomal entrapment of suramin

The liposomal entrapment of suramin and similar compounds in phospholipid vesicles was examined. For dipalmitoylphosphatidylcholine (DPPC) liposomes, entrapment percentages ranged from 25 to 65% with 3-25 mM phospholipid for aqueous solutions containing 0.07 mM of suramin. Incorporation of 30-50 mol % cholesterol (CHL) into DPPC liposomes reduced the percentage suramin entrapment. Addition of positively-charged stearylamine (5 mol %) to DPPC/CHL liposomes increased the entrapment from 2.3% to 30.3%. Entrapment was not affected by the incorporation of negatively-charged phosphatidylglycerol into DPPC/CHL liposomes. When the amount of suramin was increased from 0.07 to 0.7 mM, the entrapment percentage decreased from 37% to 11% when DPPC was held constant at 6 mM. The entrapment of 0.07 mM Evans blue, a molecule similar in structure to suramin, was 51.6% in DPPC liposomes for 6 mM phospholipid. The entrapment percentage, however, decreased by about 50% when incorporated into 7:3 (DPPC/CHL) liposomes. The liposomal entrapment of disodium 1,5-naphthalenedisulfonic acid (5.5%) and sodium 3-amino-2,7-naphthalene-disulfonic acid (1.2%) was very low compared to that of suramin or Evans blue. Differential scanning calorimetry studies of suramin and an aqueous dispersion of DPPC showed an apparent interaction between them. These observations suggest that a significant portion of the entrapped suramin results from binding of suramin to the surface of or intercalation into the liposomal bilayer. Surface binding or intercalation into the phospholipid bilayer may be attributed to both ionic and hydrophobic interactions. The ionic interaction would arise from the suramin sulfonate groups associating with the cationic choline portion of the phospholipid.(ABSTRACT TRUNCATED AT 250 WORDS)

Steady-state kinetic studies with the polysulfonate U-9843, an HIV reverse transcriptase inhibitor

The tetramer of ethylenesulfonic acid (U-9843) is a potent inhibitor of HIV-1 RT* and possesses excellent antiviral activity at nontoxic doses in HIV-1 infected lymphocytes grown in tissue culture. Kinetic studies of the HIV-1 RT-catalyzed RNA-directed DNA polymerase activity were carried out in order to determine if the inhibitor interacts with the template primer or the deoxyribonucleotide triphosphate (dNTP) binding sites of the polymerase. Michaelis-Menten kinetics, which are based on the establishment of a rapid equilibrium between the enzyme and its substrates, proved inadequate for the analysis of the experimental data. The data were thus analyzed using steady-state Briggs-Haldane kinetics assuming that the template: primer binds to the enzyme first, followed by the binding of the dNTP and that the polymerase is a processive enzyme. Based on these assumptions, a velocity equation was derived which allows the calculation of all the specific forward and backward rate constants for the reactions occurring between the enzyme, its substrates and the inhibitor. The calculated rate constants are in agreement with this model and the results indicated that U-9843 acts as a noncompetitive inhibitor with respect to both the template:primer and dNTP binding sites. Hence, U-9843 exhibits the same binding affinity for the free enzyme as for the enzyme-substrate complexes and must inhibit the RT polymerase by interacting with a site distinct from the substrate binding sites. Thus, U-9843 appears to impair an event occurring after the formation of the enzyme-substrate complexes, which involves either an event leading up to the formation of the phosphoester bond, the formation of the ester bond itself or translocation of the enzyme relative to its template:primer following the formation of the ester bond.

Chemical modifications of aminonaphthalenesulfonic acid derivatives increase effectivity and specificity of reverse transcriptase inhibition and change mode of action of reverse transcriptase and DNA polymerase alpha inhibition

The reverse transcriptase (RT) inhibition and the specificity of 15 aminonaphthalenesulfonic acid derivatives were examined with RT of a simian immunodeficiency virus derived from an African green monkey (SIVagmTYO-7). The two compounds with the strongest RT inhibition (NF415) or the highest specificity (NF345), together with suramin, were evaluated against polymerase alpha-primase complex from calf thymus. We have also compared the kinetics of inhibition of the viral and the cellular polymerase by these three compounds. While RT inhibition followed a mixed competitive and non-competitive mechanism, inhibition of the DNA polymerase alpha was competitive for suramin and non-competitive for NF415 and NF345. Certain structural characteristics appeared to be common for specific RT inhibitors.

Sulfonic acid polymers are potent inhibitors of HIV-1 induced cytopathogenicity and the reverse transcriptases of both HIV-1 and HIV-2

Four novel sulfonic acid polymers were evaluated for their in vitro HIV-1 and HIV-2 reverse transcriptase (RT) inhibitory activity and found to be equipotent against both RTs. The aromatic polymers demonstrated IC50 values that were approximately 10(3)-fold lower than those observed with the aliphatic polymers. Among the aromatic polymers, poly(4-styrenesulfonic acid) (PSS) (MW 8000; IC50 = 0.02 microgram/ml) was 3-fold more potent than poly(anetholesulfonic acid) (PAS) of approximately the same molecular weight range. The activity of PSS polymers increased in proportion to the size of the polymers and, relative to suramin, activity could be enhanced over 200-fold. These polymers also inhibited the cytopathic effect of HIV-1 at concentrations that were non-toxic to MT-4 cells. The potent RT inhibitory properties of these stable sulfonic acid polymers suggest that structure-activity studies are warranted to yield agents capable of inhibiting multiple stages of the viral process.

Selective inhibition of human cytomegalovirus replication by naphthalenedisulfonic acid derivatives

Several naphthalenedisulfonic acid derivatives were found to be selective inhibitors of human cytomegalovirus (CMV) replication in MRC-5 cells. Among the test compounds, the bis-naphthalenedisulfonic acid derivative having an hexamethylene spacer emerged as the most potent inhibitor of CMV replication. Its 50% antivirally effective concentration (EC50) for AD-169 strain was 12 microM, whereas the compound did not affect the growth of mock-infected MRC-5 cells at concentrations up to 500 microM. The naphthalenedisulfonic acid derivatives were also inhibitory to CMV clinical isolates. Virus yield reduction assay revealed that the compounds significantly reduced virus growth in CMV-infected MRC-5 cells. The bis-naphthalenedisulfonic acid derivatives with an hexamethylene spacer suppressed the expression of CMV-induced immediate early, and early antigens at a concentration of 20 microM, whereas the anti-CMV nucleoside ganciclovir did not do so even at the concentration that was 10-fold higher than its EC50 for CMV-induced plaque formation. Furthermore, naphthalenedisulfonic acid derivatives had to be present at the time of virus infection to exert their anti-CMV activity. These results suggest that the compounds are targeted at an early event in the virus replicative cycle, presumably, virus adsorption.

Quinobene, a new potent anti-HIV agent

A simple synthesis of the sulfonated azo dye Quinobene (3) and its derivatives, as well as the results of their evaluation in anti-HIV screening have been described. Thus, reacting the diazonium salt of 4,4'-diaminostilbene-2,2'-disulfonic acid with 8-hydroxyquinoline-5-sulfonic acid yielded the readily isolable title compound. The lithium and tetramethylammonium salts of Quinobene and its complexes with Cu(II), Zn(II), Mg(II) were also prepared. In vitro tests showed considerable activity of these compounds against HIV-1.

Sulfonic acid polymers as a new class of human immunodeficiency virus inhibitors

Four sulfonic acid polymers [poly(4-styrenesulfonic acid)(PSS), poly(anetholesulfonic acid)(PAS), poly(vinylsulfonic acid)(PVS), poly(2-acrylamido-2-methyl-1-propanesulfonic acid)(PAMPS)] have been found to inhibit the cytopathicity of HIV-1 and HIV-2 in MT-4 cells at concentrations that are not toxic to the host cells. The sulfonic acid polymers also inhibited syncytium formation in co-cultures of MOLT-4 cells with HIV-1- or HIV-2-infected HUT-78 cells. They also inhibited binding of anti-gp120 mAb to HIV-1 gp120 and blocked adsorption of HIV-1 virions to MT-4 cells. PSS and PAS, but not PVS and PAMPS, interfered with the binding of OKT4A/Leu3a to the CD4 receptor. The anti-HIV activity of these polyanionic compounds can be ascribed to inhibition of the gp120-CD4 interaction. Sulfonic acid polymers represent a lead of anti-HIV compounds that warrant further evaluation of their therapeutic potential.

Anti-AIDS drug development: challenges and strategies

A myriad of chemical derivatives has been shown to inhibit in vitro replication of the AIDS virus at concentrations that are nontoxic to the host cells. The majority of these agents acts by either (i) inhibiting enzymes such as reverse transcriptase (RT), protease, or glucosidase, (ii) arresting expression of genes or gene products, or (iii) inhibiting viral processes such as giant cell (syncytia) formation or viral binding to the target cell. The nucleoside RT inhibitors are the most widely studied agents at both the preclinical and the clinical levels. Their inability to cure AIDS has stimulated the discovery of several novel nonnucleoside RT inhibitors, possessing varied structures and demonstrating activity at nanomolar concentrations. These agents demonstrate a unique mode of binding to RT and show a high specificity for HIV-1. Protease inhibitors, soluble CD4 derivatives, oligonucleotides, and many anionic derivatives also demonstrate potent anti-HIV-1 activities. These derivatives possess mechanisms of action different to the nucleosides and exhibit selectivity as exemplified by their high in vitro therapeutic indices. This article discusses the structural parameters that govern activity in these agents, the pros and cons regarding the development of these compounds as putative anti-AIDS agents, and the future promise of searching for newer agents directed at novel targets to inhibit the AIDS virus.