High anti-HIV Activity Research Articles

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.

Anti-AIDS agents. 60. Substituted 3'R,4'R-di-O-(-)-camphanoyl-2',2'-dimethyldihydropyrano[2,3-f]chromone (DCP) analogues as potent anti-HIV agents.

Synthesis of positional isomers is a commonly used technique in drug design. Accordingly, based on prior SAR studies of 3'R,4'R-di-O-(S)-camphanoyl-(+)-cis-khellactone (DCK, 1) analogues, a series of mono- and disubstituted chromone derivatives of 3'R,4'R-di-O-(-)-camphanoyl-2',2'-dimethyldihydropyrano[2,3-f]chromone (DCP, 4) were designed and synthesized. Together with 1 and 4-methyl DCK (2), all newly synthesized DCP analogues (4-21) were screened for anti-HIV-1 activity against a non-drug-resistant strain in H9 lymphocytes and a multiple reverse transcriptase (RT) inhibitor-resistant strain in the MT4 cell line. Several DCP analogues (4, 5, 7, 8, 13, and 17) exhibited extremely high anti-HIV activity in the non-drug-resistant strain assay, with EC(50) values ranging from 0.00032 to 0.0057 microM and remarkable therapeutic indexes (TI) ranging from 5.6 x 10(3) to 1.16 x 10(5), which were similar to those of 2 (EC(50) 0.0059 microM, TI > 6.6 x 10(3)) and better than those of 1 (EC(50) 0.049 microM, TI > 328). Even more promisingly, some DCP analogues also showed activity against a multi-RT inhibitor-resistant strain, HIV-1 RTMDR1, whereas most DCK analogues did not. The most significant compound was 8, with an EC(50) value of 0.06 microM and TI of 718 against the multi-RT inhibitor-resistant HIV-1 strain. Compounds 9 and 10 also showed good activity with an EC(50) value of 0.14 microM, and TIs of 272 and >111, respectively. 2-Ethyl DCP (8) exhibited the best anti-HIV activity in both assays. Further development of 8-related compounds as clinical trial candidates is warranted.

Synthesis and anti‐HIV activity of sulfated astragalus polysaccharide

AbstractSulfated astragalus polysaccharide (sulfated astragalan, SA) was prepared by chemical modification of astragalus polysaccharide abstracted from an astragalus menbranceus used as a Mongolia herbal medicine. Anti‐HIV activity of SA was assayed in vitro and the results indicated that the SA showing high anti‐HIV activity and lower cytotoxity. Sulfation of astragalan was carried out by using sulfur trioxide‐pyridine complex in a mixture of dimethylsulfoxide (DMSO) to give sulfated astragalan with degree of substitution (DS) of 1.14–1.20 and a number average molecular weight (Mn) of 1.27–1.46 × 104. Copyright © 2003 John Wiley & Sons, Ltd.

Enhancement of the T140-based pharmacophores leads to the development of more potent and bio-stable CXCR4 antagonists.

A CXCR4 antagonistic peptide, T140, and its bio-stable analogs, such as Ac-TE14011, were previously developed. These peptides inhibit the entry of T cell line-tropic strains of HIV-1 (X4-HIV-1) into T cells. Herein, a series of TE14011 analogs having modifications in the N-terminal region were synthesized to develop effective compounds with increased biostability. Among these analogs, 4F-benzoyl-TE14011 (TF14013) showed the strongest anti-HIV activity derived from CXCR4-antagonism, suggesting that a 4-fluorobenzoyl moiety at the N-terminus of T140 analogs constitutes a novel T140-based pharmacophore for CXCR4 antagonists. Structure-activity relationship (SAR) studies on TE14011 analogs with N(alpha)-acylation by several benzoic acid derivatives have disclosed a significant relationship between the anti-HIV activity and the Hammett constant (sigma) of substituted benzoic acids. TF14013 was found to be stable in mouse serum, but not completely stable in rat liver homogenate due to deletion of the C-terminal Arg14-NH2 from the parent peptide. This biodegradation was completely suppressed by N-alkyl-amidation at the C-terminus. Taken together, the enhancement of the T140-based pharmacophores led to development of a novel CXCR4 antagonist, 4F-benzoyl-TE14011-Me (TF14013-Me), which has very high anti-HIV activity and increased biostability.

Certification of the Critical Importance of l-3-(2-Naphthyl)alanine at Position 3 of a Specific CXCR4 Inhibitor, T140, Leads to an Exploratory Performance of Its Downsizing Study

We have previously found that a 14-amino acid residue-peptide, T140, inhibits infection of target cells by T cell line-tropic HIV-1 (X4-HIV-1) through its specific binding to a chemokine receptor, CXCR4. Here, the importance of an l-3-(2-naphthyl)alanine (Nal) residue at position 3 in T140 for high anti-HIV activity and inhibitory activity against Ca2+ mobilization induced by stromal cell-derived factor (SDF)-1α-stimulation through CXCR4 has initially been shown by the synthesis and biological evaluation of several analogues, where Nal3 is substituted by diverse aromatic amino acids. Next, the order of the N-terminal 3 residues (Arg1-Arg2-Nal3) has been proved to be important from the structure–activity relationship (SAR) study shuffling these residues. Based on these results, we have found 10-residue peptides possessing modest anti-HIV activity by systematic antiviral evaluation of a series of synthetic, shortened analogues of T140.

Lipid-based delivery of combinations of antisense oligodeoxynucleotides for the in vitro inhibition of HIV-1 replication.

We evaluated a new approach to AIDS therapy by using combinations of oligodeoxynucleotides (ODNs), delivered with a lipid-based carrier system, that target different HIV viral genome sites. We identified some of the factors that seem to influence the effectiveness of a combination strategy in cell cultures including ODN concentrations, type of infection (acute vs chronic), backbone modification of the ODN, and the number of sequences. When delivered by the DLS carrier system, some advantages of using a combination of ODNs over treatment with only one ODN could be observed in acute infection assays but not in the chronic infection model. These results suggest that in the acute infection model, the 3 different antisense ODNs in the "cocktail" might block an early step of virus replication by combined inhibitory effects. Various combinations of phosphorothioate-modified (PS) and unmodified oligonucleotides delivered by the DLS system were compared for their antiviral activity in a long-term acute assay using HIV-1 (IIIB strain)-infected MOLT-3 cells. The most effective combination had 3 phosphorothioate antisense ODNs: Srev, SDIS, and SPac (>99% inhibition at 100 pM). However, the additive effect determined when using ODN combinations was rather low, revealing the high level of nonsequence specificity in HIV-1 cell culture models. Data illustrated the high sequence nonspecific activity of ODNs, especially when comparing activity of antisense ODNs with activity of random control sequence ODNs. The latter exhibited an inhibitory effect similar to that of antisense ODNs under our experimental conditions. Nevertheless, we demonstrated that it is possible to achieve high anti-HIV activity by using, in combination, picomolar range concentrations of antisense oligonucleotides complexed to a lipid-based carrier system such as the DLS system, without increasing cell toxicity.

Synthesis, Enzymatic Hydrolysis, and Anti-HIV Activity of AZT−Spacer−Curdlan Sulfates

An AIDS (acquired immunodeficiency syndrome) drug, azidothymidine (AZT), was bound by an ester bond onto curdlan sulfate having both anti-HIV activity and the property of accumulating in lymphoid tissues to produce a series of biodegradable AZT−aliphatic-dicarboxylate−curdlan sulfates (designated as AZT−spacer−curdlan sulfates). When the carbon number of the alkylene group was 2−12, AZT−spacer−curdlan sulfates exhibited high anti-HIV activities in the EC50 range of 0.04 − 0.21 μg/mL and low cytotoxicities of CC50 of more than 1000 μg/mL. AZT−dodecanedicarboxylate−curdlan sulfate with the highest anti-HIV activity was easily hydrolyzed by esterase−enzymatic hydrolysis to release free AZT. Furthermore, an acidically released AZT from curdlan sulfate exhibited its high anti-HIV activity. AZT−dodecanedicarboxylate−curdlan sulfate showed a low anticoagulant activity of 7 unit/mg.

NMR Studies on Structure and Action Mechanism of Sulfated Dodecyl Laminaripentaoside with High Anti-Human Immunodeficiency Virus Activity

Anti-HIV (human immunodeficiency virus) active sulfated dodecyl laminaripentaosides having various degrees of sulfation were synthesized and their structures analyzed by 2D NMR spectroscopic measurements such as C-H direct, C-H long-range, H-H direct, NOESY, and HOHAHA. The 6-hydroxyl was first sulfated, followed by the sulfation of the 2-hydroxyl and the 4-hydroxyl, in the sulfation of dodecyl laminaripentaoside. Interactions between sulfated dodecyl laminaripentaoside and poly- or oligo-lysine as a virus protein model compound were analyzed. The reason why high degree of sulfation was necessary for obtaining high anti-HIV activity in vitro was strong ionic interactions existed between oligo-lysine and sulfated laminaripentaosides with high degree of sulfation. In the gel formed by the interaction the local motion of the sulfated oligosaccharide was restricted to a large extent, whereas that of the alkyl portion was not restricted so much.

A quantum chemical and statistical study of flavonoid compounds with anti-HIV activity

The molecular orbital semi-empirical method PM3 is employed to calculate a set of molecular properties (variables) of 21 flavonoid compounds with anti-HIV activity. Pattern recognition techniques, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed in order to reduce dimensionality, and investigate which subset of variables would be more effective in classifying the flavonoid compounds according to their degree of anti-HIV activity. The principal component and hierarchical cluster studies showed that the variables LUMO (the energy of the lowest unoccupied molecular orbital), χ (electronegativity), and Q2, Q3 and Q7 (charges on atoms 2, 3 and 7) are related to the compounds with higher anti-HIV activity. These variables keep the more active flavonoids clustered together and separate them from those less active when principal component analysis and hierarchical cluster analysis are employed.

Synthesis of polymethacrylate derivatives having sulfated maltoheptaose side chains with anti‐HIV activities

Anti-HIV (human immunodeficiency virus) active polymethacrylates having pendant sulfated oligosaccharides were synthesized, and the relationship between structures and biological activities of the polymethacrylates was examined. Acetylated 1-O-methacryloyl maltoheptaoside (MA-AcM7) was polymerized with AIBN as an initiator to give polymethacrylates having a pendant acetylated maltoheptaose in every repeating unit, poly(MA-AcM7)s. After hydroxyl groups were recovered by deacetylation, the polymethacrylates having maltoheptaose units, poly(MA-M7)s, were sulfated to give polymethacrylates having sulfated maltoheptaose side-chains, poly(MA-SM7)s, with degrees of sulfation of 1.1 to 2.7 (maximum, 3.0). These polymethacrylates including sulfated oligosaccharides exhibited low anti-HIV activities represented by the 50% protecting concentration (EC50) in the range of 15–62 μg/mL and low blood anticoagulant activities around 10 unit/mg (standard dextran sulfate, 22.7 unit/mg). The anti-HIV activity increased with increasing degree of sulfation to reach EC50 of 15–16 μg/mL. In addition, copolymerization of MA-AcM7 with methyl methacrylate (MMA) and subsequent sulfation gave polymethacrylates consisting of various proportions of highly sulfated maltoheptaose and MMA units. It was revealed that the anti-HIV activity increased with decreasing proportion of the sulfated oligosaccharide moiety and that a copolymethacrylate having 22 mol % of sulfated maltoheptaose units (DS = 3.0) had a high anti-HIV activity in the EC50 of 0.3 μg/mL. The blood anticoagulant activity increased slightly from 9 to 18 unit/mg with decreasing proportion of the sulfated maltoheptaose units. These results suggested that the biological activities were influenced strongly by the spatial distance between sulfated oligosaccharide substituents in the polymethacrylate main chain. Distinction and conformation of the oligosaccharide side chains also played an important role. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 789–800, 1999

Synthesis of polymethacrylate derivatives having sulfated maltoheptaose side chains with anti-HIV activities

Anti-HIV (human immunodeficiency virus) active polymethacrylates having pendant sulfated oligosaccharides were synthesized, and the relationship between structures and biological activities of the polymethacrylates was examined. Acetylated 1-O-methacryloyl maltoheptaoside (MA-AcM7) was polymerized with AIBN as an initiator to give polymethacrylates having a pendant acetylated maltoheptaose in every repeating unit, poly(MA-AcM7)s. After hydroxyl groups were recovered by deacetylation, the polymethacrylates having maltoheptaose units, poly(MA-M7)s, were sulfated to give polymethacrylates having sulfated maltoheptaose side-chains, poly(MA-SM7)s, with degrees of sulfation of 1.1 to 2.7 (maximum, 3.0). These polymethacrylates including sulfated oligosaccharides exhibited low anti-HIV activities represented by the 50% protecting concentration (EC 50 ) in the range of 15-62 μg/mL and low blood anticoagulant activities around 10 unit/mg (standard dextran sulfate, 22.7 unit/mg). The anti-HIV activity increased with increasing degree of sulfation to reach EC 50 of 15-16 μg/mL. In addition, copolymerization of MA-AcM7 with methyl methacrylate (MMA) and subsequent sulfation gave polymethacrylates consisting of various proportions of highly sulfated maltoheptaose and MMA units. It was revealed that the anti-HIV activity increased with decreasing proportion of the sulfated oligosaccharide moiety and that a copolymethacrylate having 22 mol % of sulfated maltoheptaose units (DS = 3.0) had a high anti-HIV activity in the EC 50 of 0.3 μg/mL. The blood anticoagulant activity increased slightly from 9 to 18 unit/mg with decreasing proportion of the sulfated maltoheptaose units. These results suggested that the biological activities were influenced strongly by the spatial distance between sulfated oligosaccharide substituents in the polymethacrylate main chain. Distinction and conformation of the oligosaccharide side chains also played an important role.

Synthesis of sulfated oligosaccharide glycosides having high anti-HIV activity and the relationship between activity and chemical structure

Sulfated laminara-oligosaccharide glycosides having high anti-human immunodeficiency virus (HIV) activities were synthesized from laminara-tetraose, -pentaose and -hexaose. The oligosaccharide glycosides were synthesized by treating peracetylated β-oligosaccharides with various alcohols and Lewis acid catalysts. The effects of the number of glucose residues and the alkyl chain-length on anti-HIV activity were examined. The anti-HIV activity of sulfated dodecyl laminara-pentaosides and -hexaosides increased with increasing degree of sulfation (DS) and the pentaoside having an almost fully-sulfated saccharide portion had the highest activity, whereas for the hexaoside a somewhat lower DS manifested the highest activity. Sulfated laminara-oligosaccharide glycosides having fluoroalkyl-containing aglycons of high hydrophobicity showed potent inhibitory effects against HIV infection. In contrast, hydrophilic substituents containing oligo(ethyleneoxy) groups as aglycons in the sulfated oligosaccharides did not show high anti-HIV activity.

Synthesis and anti-HIV activity of catanionic analogs of galactosylceramide

Two-chain and gemini catanionic analogs of galactosylceramide were easily prepared in quantitative yields, affording high anti-HIV activities with low cytotoxicities on human cells (e.g. for gemini 4b an EC50 of 0.5 µM with a CC50 of >100 µM were obtained).

Synthesis of sulfonated amino-polysaccharides having anti-HIV and blood anticoagulant activities

Sulfonated 3-amino-3-deoxy-( 1 → 6)- α- d-allopyranans were synthesized to elucidate the relationship between structure and such specific biological activities as anti-HIV and blood anticoagulant activities. Ring-opening copolymerization of 1,6-anhydro-3-azido-2,4-di- O-benzyl-3-deoxy- β- d-allopyranose 1 with 1,6-anhydro- 2,3,4-tri- O-benzyl- β- d-allopyranose 2 with PF 5 catalyst gave copolymers having various proportions of the 1 unit. 13C NMR spectroscopy showed the resulting copolymers to have α-( 1 → 6)-stereoregularity, and the monomer reactivity ratios were calculated to be r 1 =0.92 and r 2 =1.11 by the Kelen–Tüdös method. Reduction of the azido groups and subsequent debenzylation of the copolymers afforded new amino-polysaccharides consisting of 3-amino-3-deoxy-allose and allose units. Sulfonation of 3-amino-3-deoxy-( 1 → 6)- α- d-allopyranan and copolysaccharides consisting of 3-amino-allose and allose or glucose units was performed with piperidine- N-sulfonic acid to give polysaccharides containing sulfoamido and sulfonate groups in good yields. The sulfoamido-copolysaccharides containing of 3-amino-3-deoxy-allose and glucose units exhibited high anti-HIV activities manifested by the 50% protecting concentration (EC 50) of 0.2–0.5 mg/mL and low cytotoxicity shown by a 50% cytotoxic concentration (CC 50) of >1000 μg/mL. The sulfoamido-copolysaccharides containing 3-amino-allose and allose units had somewhat lower anti-HIV activities (EC 50=0.8–0.9 μg/mL) and slightly higher cytotoxicities (CC 50=740∼797 μg/mL). In addition, it was found that the blood anticoagulant activity increased, with increasing proportion of the amino-allose unit, from 30 to 58 unit/mg (standard dextran sulfate, 22.7 unit/mg). These results suggest that the sulfonated 3-amino-3-deoxyallose unit plays important roles on both anti-HIV and blood anticoagulant activities.

Synthesis of Azidothymidine-Bound Sulfated Alkyl Oligosaccharides and Their Inhibitory Effects on AIDS Virus Infection in vitro

In order to sustain an acquired immunodeficiency syndrome (AIDS) drug azidothymidine (AZT) in high level in the blood, novel AZT prodrugs, i.e., AZT-bound sulfated laminaripentaose and AZT-bound sulfated alkyl laminaripentaosides, were synthesized. AZT was introduced into the backbone of laminaripentaose and alkyl laminaripentaoside through biodegradable ester bond to give AZT-bound laminaripentaose and AZT-bound alkyl laminaripentaoside, respectively. Subsequently, they were sulfated with SO3-pyridine complex to produce AZT-bound sulfated laminaripentaose and AZT-bound sulfated alkyl laminaripentaoside. Their anti-Human Immunodeficiency Virus (HIV) activities were assayed in vitro by use of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) method. It was revealed that AZT-bound sulfated laminaripentaose exhibited much higher anti-HIV activity (EC50=0.20 μg ml−1) than AZT-free sulfated laminaripentaose (EC50=160 μg ml−1) even when AZT was not released from sulfated laminaripentaose, and a low cytotoxicity of CC50 above 1000 μg ml−1. Moreover, an alkyl group combined to the reducing end of AZT-bound sulfated alkyl laminaripentaoside increased the anti-HIV activity further (EC50=0.04–0.23 μg ml−1). In addition, AZT-bound sulfated alkyl laminaripentaoside possessed a very low or undetectable anticoagulant activity.

First synthesis of the antimalarial naphthylisoquinoline alkaloid dioncophylline C, and its unnatural anti-HIV dimer, jozimine C

The first total synthesis of dioncophylline C, a new antimalarial lead structure, is described. For the directed construction of the stereogenic biaryl axis, the ‘lactone methodology’ is applied, despite the lack of a ‘bridgehead oxygen’ function in the target molecule. Furthermore, the novel dimer of dioncophylline C, ‘jozimine C’, is prepared, by oxidative phenolic coupling of the protected natural monomer. Jozimine C displays good antimalarial activity ( Plasmodium falciparum; IC 50 = 0.445 μg/ml), and, in particular, represents the first unnatural dimer of a naphthylisoquinoline alkaloid with a high anti-HIV activity (HIV-1; EC 50 = 27 μg/ml).

Preparation and anti-HIV activity of low-molecular-weight carrageenans and their sulfated derivatives

Lambda-, kappa-, and iota-carrageenan were depolymerized in the presence of ferrous ions or ferrous ions plus ascorbic acid at room temperature. Tetrabutyl-ammonium salts of lambda-, kappa- and iota-carrageenan were dissolved in N,N-dimethylformamide and sulfated by the addition of pyridine-sulfur trioxide in N,N-dimethylformamide. Then, the sulfated carrageenans were depolymerized by the incubation with ferrous ions and ascorbic acid. The anti-HIV activities of the various preparations were determined in a system in which MT-4 cells were infected with HTLV-IIIB. The activity of lambda-carrageenan was similar to that of dextran sulfate and the depolymerized lambda-carrageenan retained high activity. The activities of kappa- and iota-carrageenan and their depolymerized forms were about 6% of that of lambda-carrageenan. The sulfation of kappa-and iota-carrageenan increased the activities of these compounds to the same level as that of lambda-carrageenan. However, the sulfation of lambda-carrageenan did not affect its activity. Depolymerized sulfated kappa- and iota-carrageenan with mean molecular weights of 50,000 (81,000-46,000) had higher anti-HIV activity than dextran sulfate and all other preparations of carrageenan tested.

The Relationship between Conformation and Biological Activity of 8-substituted Analogues of 2′,5′-Oligoadenylates

Analogues of the 2′,5′-linked adenylate trimer 5′-monophosphates, p5′A2′p5′A2′p5′A (pA3) (1a), containing 8-hydroxyadenosine and 8-mercaptoadenosine in the first, second, and third nucleotide positions were tested for their ability to bind to and activate RNase L of mouse L cells. The oligomer, p5′ASH2′p5′ASH2′p5′ASH(pASH3) (1c) had little capacity to bind to RNase L. On the other hand, an analogue of the p5′AOH2′p5′AOH2′p5′AOH(pAOH3) (1b) bound almost as well as the parent 2-5A [pppA(2′p5′A)2] (P3A3) (1d) to RNase L. The 8-substituted analogues of 2-5A were more resistant to degradation by (2′,5′) phosphodiesterase. Finally, the monophosphate, pASH3(1c) which possessed higher anti-HIV activity than pAg (1a) or pAOH3(1b).

Anticoagulant Activity of Sulfated Schizophyllan

Sulfated schizophylians with lower anticoagulant activity and higher anti-HIV activity were prepared. Those with sulfur contents above 6% showed anticoagulant activity irrespective of molecular weight. The activity was correlated with sulfur content. The triple helical structure of sulfated schizophylians did not affect their anticoagulant activity. A sulfated schizophyllan with a sulfur content of 5.0% showed low anticoagulant activity and good anti-HIV activity. These results indicate that the latter sulfated schizophyllan (sulfur content, 5%) would be useful as an anti-HIV agent for treatment of HIV-infected hemophiliacs.

A novel anti-HIV synthetic peptide, T-22 ([Tyr 5,12,Lys 7]-polyphemusin II)

Tachyplesin and polyphemusin are antimicrobial peptides recently isolated from the hemocytes of horseshoe crabs ( Tachypleus tridentatus and Limulus polyphemus). We synthesized them and their analogs and examined their antiviral activity against human immunodeficiency virus (HIV) type 1 in vitro. The infection of human T cells with the virus was markedly inhibited by some of them at low concentrations. In this structure-activity study, we found that [Tyr 5,12, Lys 7]-polyphemusin II, which was designated as T22, had extremely high anti-HIV activity. Its 50% inhibitory concentration (EC 50) was 0.008 μg/ml, while its 50% cytotoxic concentration (CC 50) was 54 μg/ml and these values were comparable to those of AZT. This result indicates that T22 would be a potential candidate for the therapy of HIV infection.