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Design and synthesis of photoactivatable aryl diketo acid-containing HIV-1 integrase inhibitors as potential affinity probes.

Aryl diketo acids (ADKs) represent an important new class of HIV-1 integrase (IN) inhibitors. In order to facilitate examination of the structural basis underlying IN?ADK interaction, biphenyl ketone and phenyl azide photophores were incorporated into ADK structures. Of particular note is the novel dual utilization of azide and phenyketone moieties for both enzyme recognition and for crosslinking. The resulting analogues maintained low micromolar inhibitory potency against IN in recombinant in vitro assays. These potential HIV-1 integrase photoaffinity labels may provide useful tools for studying enzyme interactions of the ADK inhibitor class.

Drug Design↗

Retroviral integrase inhibitors year 2000: update and perspectives.

HIV-1 integrase is an essential enzyme for retroviral replication and a rational target for the design of anti-AIDS drugs. A number of inhibitors have been reported in the past 8 years. This review focuses on the recent developments in the past 2 years. There are now several inhibitors with known sites of actions and antiviral activity. The challenge is to convert these leads into drugs that will selectively target integrase in vivo, and can be added to our antiviral armamentarium.

Anti-HIV Agents↗

A new class of HIV-1 integrase inhibitors: the 3,3,3', 3'-tetramethyl-1,1'-spirobi(indan)-5,5',6,6'-tetrol family.

Integration is a required step in HIV replication, but as yet no inhibitors of the integration step have been developed for clinical use. Many inhibitors have been identified that are active against purified viral-encoded integrase protein; of these, many contain a catechol moiety. Though this substructure contributes potency in inhibitors, it is associated with toxicity and so the utility of catechol-containing inhibitors has been questioned. We have synthesized and tested a systematic series of derivatives of a catechol-containing inhibitor (1) with the goal of identifying catechol isosteres that support inhibition. We find that different patterns of substitution on the aromatic ring suffice for inhibition when Mn(2+) is used as a cofactor. Importantly, the efficiency is different when Mg(2+), the more likely in vivo cofactor, is used. These data emphasize the importance of assays with Mg(2+) and offer new catechol isosteres for use in integrase inhibitors.

Antiviral Agents↗

Combinations of reverse transcriptase, protease, and integrase inhibitors can be synergistic in vitro against drug-sensitive and RT inhibitor-resistant molecular clones of HIV-1.

Combinations of anti-HIV agents including one or two reverse transcriptase inhibitors with a protease inhibitor are potent and effective. However, toxicities, costs and the emergence of drug-resistant organisms have compromised their long-term efficacy in people. A next, likely, target for anti-HIV therapy is HIV-1 integrase. Viral integration, catalyzed by integrase, is absolutely required for HIV replication. L-chicoric acid is a potent and selective inhibitor of HIV-1 integrase that also inhibits HIV-1 replication in cell culture. As a first step in understanding the potential role for integrase inhibitors in clinical medicine, the activities of L-chicoric acid alone and in combination with 2', 3'-dideoxycytidine, zidovudine, and a protease inhibitor, nelfinavir, were tested in vitro against molecular clones of HIV-1 resistant to reverse transcriptase inhibitors. L-chicoric acid was equally effective against a wild-type clone of HIV-1, HIV(NL4-3), or against HIV-1 resistant to either zidovudine or dideoxycytidine. L-chicoric acid was largely synergistic with zidovudine and synergistic with both dideoxycytidine and nelfinavir.

Anti-HIV Agents↗

The use of a new in vitro reaction substrate reproducing both U3 and U5 regions of the HIV-1 3'-ends increases the correlation between the in vitro and in vivo effects of the HIV-1 integrase inhibitors.

Human Immunodeficiency Virus type 1 (HIV-1) integrase (IN) is an attractive target for the development of new antiviral therapies. Recently, several HIV-1 recombinant IN (rIN) in vitro inhibitors have been described. However, the great majority of them failed to block the virus replication in cell-based assays, suggesting the inadequacy of the in vitro assay systems used for inhibitor screening. To improve these systems, we designed a 40(mer) duplex DNA reaction substrate consisting of recognition sequences from both U3 and U5 HIV-1 long terminal repeat (LTR) termini. The HIV-1 rIN was able to catalyze its enzyme activities recognizing both ends of the 40(mer) dsDNA. Using this substrate we assayed the effects on rIN catalysis of different classes of compounds which inhibit the HIV-1 rIN in vitro when the reaction substrate is the standard 21(mer) U5 dsDNA, and that are either active or inactive on the HIV-1 replication. We also compared the efficacy of these compounds when added to the reaction before or after the formation of the rIN-dsDNA complex. In this system, the enzyme preincubation with the two-ended 40(mer) dsDNA before the addition of the compounds allowed a strong correlation between the effects of hydroxylated aromatics derivatives on rIN activity in cell-free assays and their effects on viral replication in cell-culture assays. This increase in drug selectivity of the rIN in vitro assay was explored by investigating whether it was due to the length of the 40(mer), longer than the standard 21(mer), or to presence of both viral ends, versus only one viral end. To this purpose we designed four 40(mer) oligonucleotides containing either only one viral end or two-repetitive ends, finding that the architecture of the rIN-dsDNA complex and its compound susceptibility is significantly influenced by the sequence of the dsDNA substrate.

Anti-HIV Agents↗

Synthesis and biological evaluation of novel 5(H)-phenanthridin-6-ones, 5(H)-phenanthridin-6-one diketo acid, and polycyclic aromatic diketo acid analogs as new HIV-1 integrase inhibitors.

A new series of phenanthridinone derivatives, and diketo acid analogs, as well as related phenanthrene and anthracene diketo acids have been synthesized and evaluated as HIV integrase (IN) inhibitors. Several new beta-diketo acid analogs with the phenanthridinone scaffold replaced by phenanthrene, anthracene or pyrene exhibited the highest IN inhibitory potency. There is a general selectivity against the integrase strand transfer step. The most potent IN was 2,4-dioxo-4-phenanthren-9-yl-butyric acid (27f) with an IC(50) of 0.38microM against integrase strand transfer. The phenanthrene diketo acids 27d-f were more potent (IC(50)=2.7-0.38microM) than the corresponding phenanthridinone diketo acid 16 (IC(50)=65microM), suggesting that the polar amide bridge in the phenanthridinone system decreases inhibitory activity relative to the more lipophilic phenanthrene system. This might have to do with the possible binding of the aryl group of the compounds binding to a lipophilic pocket at the integrase active site as suggested by the docking simulations. Molecular modeling also suggested that effectiveness of chelation of the active site Mg(2+) contributes to IN inhibitory potency. Finally, some of the potent compounds inhibited HIV-1 replication in human peripheral blood mononuclear cells (PBMC) with EC(50) down to 8microM for phenanthrene-3-(2,4-dioxo)butyric acid (27d), with a selectivity index of 10 against PBMCs.

Animals↗

2,6-Bis(3,4,5-trihydroxybenzylydene) derivatives of cyclohexanone: novel potent HIV-1 integrase inhibitors that prevent HIV-1 multiplication in cell-based assays.

A number of 2,6-bisbenzylidenecyclohexane-1-one derivatives have been synthesized and tested as HIV-1 integrase (IN) inhibitors with the aim of obtaining compounds capable to elicit antiviral activity at non-cytotoxic concentrations in cell-based assays. 3,5-Bis(3,4,5-trihydroxybenzylidene)-4-oxocyclohexaneacetic acid (20d) resulted one of the most potent and selective derivatives in acutely infected MT-4 cells (EC(50) and CC(50) values of 2 and 40 microM, respectively). In enzyme assays with recombinant HIV-1 integrase (rIN), this compound proved able to inhibit both 3'-processing and disintegration with IC(50) values of 0.2 and 0.5 microM, respectively. In order to develop a model capable to predict the anti HIV-IN activity and useful to design novel derivatives, we performed a comparative molecular field analysis (CoMFA) like 3-D-QSAR. In our model the ligands were described quantitatively in the GRID program, and the model was optimized by selecting only the most informative variables in the GOLPE program. We found the predictive ability of the model to increase significantly when the number of variables was reduced from 20,925 to 1327. A Q(2) of 0.73 was obtained with the final model, confirming the predictive ability of the model. By studying the PLS coefficients in informative 3-D contour plots, ideas for the synthesis of new compounds could be generated.

Anti-HIV Agents↗

Three-dimensional quantitative structure: activity relationship studies on diverse structural classes of HIV-1 integrase inhibitors using CoMFA and CoMSIA.

Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA), three-dimensional quantitative structure-activity relationship (3D-QSAR) techniques, were applied to a set of 89 HIV-1 integrase (IN) inhibitors (training set=61, test set=28), belonging to 11 structurally different classes. The biological data for 3' processing mechanism were used. For CoMFA calculations, three different fitting methods for alignment process were investigated. The best CoMFA model yielded the cross-validated r(2) r(2)(cv) =0.698 and the non-cross-validated r(2) (r(2))=0.947. The derived model indicated the importance of steric (60.8%) as well as electrostatic (39.2%) contributions. For CoMSIA calculations, different combinations of the fields were tested. The best CoMSIA model gave r(2)(cv) =0.724 and r(2)=0.864. This model showed that steric (30.3%), hydrogen bond donor (43.4%) and hydrogen bond acceptor (26.3%) properties played major roles in HIV-1 IN inhibition. The mapping of hydrogen bond interaction fields with the HIV-1 IN active site gave details on hydrogen bond forming between ligands and enzyme. These obtained results agree well with the experimental observations that there should be hydrogen bond interactions between ligands and Glu152, Lys156 and Lys159 residues. The results not only lead to a better understanding of structural requirements of HIV-1 IN inhibitors but also can help in the design of new IN inhibitors.

HIV Integrase Inhibitors↗

Human immunodeficiency virus type 1 (HIV-1) integrase: resistance to diketo acid integrase inhibitors impairs HIV-1 replication and integration and confers cross-resistance to L-chicoric acid.

The diketo acids are potent inhibitors of human immunodeficiency virus (HIV) integrase (IN). Mutations in IN, T66I, S153Y, and M154I, as well as T66I-S153Y and T66I-M154I double mutations, confer resistance to diketo acids (D. J. Hazuda et al., Science 287:646-650, 2000). The effects of these IN mutations on viral replication, enzymatic activity, and susceptibility to other HIV inhibitors are reported herein. By immunofluorescence assay and real-time PCR, all mutant viruses demonstrated a modest delay in viral spread compared to that of reference HIV. These viruses also showed a statistically significant defect in integration without defects in reverse transcription. Recombinant IN containing S153Y, T66I, and M154I-T66I mutations had an approximately twofold decrease in both disintegration and 3'-end-processing-strand transfer activities in vitro. In contrast, IN containing M154I demonstrated a greater than twofold increase in specific activity in both reactions. All mutant HIVs were resistant to l-chicoric acid, a dicaffeoyltartaric acid IN inhibitor, both in tissue culture and in biochemical assays, yet remained susceptible to the reverse transcriptase inhibitors zidovudine and nevirapine. Thus, IN mutations conferring resistance to the diketo acids can yield integration defects, attenuated catalysis in vitro, and cross-resistance to l-chicoric acid.

Caffeic Acids↗

Styrylquinazoline derivatives as HIV-1 integrase inhibitors.

Styrylquinazoline derivatives were prepared by Perkin condensation and evaluated for inhibitory activity against HIV-1 integrase. Among them, compound 5c containing a free catechol ring was the most potent (IC(50)=0.8 +/- 1.9 microM)and showed 6-fold more potency than the corresponding styrylquinoline compound (IC(50) = 130.7 +/- 8.6 microM).

HIV Integrase Inhibitors↗

4,5-dihydroxypyrimidine carboxamides and N-alkyl-5-hydroxypyrimidinone carboxamides are potent, selective HIV integrase inhibitors with good pharmacokinetic profiles in preclinical species.

The dihydroxypyrimidine carboxamide 4a was discovered as a potent and selective HIV integrase strand transfer inhibitor. The optimization of physicochemical properties, pharmacokinetic profiles, and potency led to the identification of 13 in the dihydroxypyrimidine series and 18 in the N-methylpyrimidinone series having low nanomolar activity in the cellular HIV spread assay in the presence of 50% normal human serum and very good pharmacokinetics in preclinical species.

Administration, Oral↗

Inhibition of human immunodeficiency virus type 1 isolates by the integrase inhibitor L-731,988, a diketo Acid.

L-731,988 inhibits human immunodeficiency virus (HIV) replication through integrase. In this study, approximately 600 nM L-731,988 inhibited the replication of 12 HIV type 1 isolates from multiple clades, including primary isolates and cloned viruses. These data suggest that diketo acids or their derivatives may prove useful on a worldwide basis in treating HIV infection.

Acetoacetates↗

The hunt for HIV-1 integrase inhibitors.

Currently, there are three distinct mechanistic classes of antiretrovirals: inhibitors of the HIV- 1 reverse transcriptase and protease enzymes and inhibitors of HIV entry, including receptor and coreceptor binding and cell fusion. A new drug class that inhibits the HIV-1 integrase enzyme (IN) is in development and may soon be available in the clinic. IN is an attractive drug target because it is essential for a stable and productive HIV-1 infection and there is no mammalian homologue of IN. Inhibitors of integrase enzyme (INI) block the integration of viral double-stranded DNA into the host cell's chromosomal DNA. HIV-1 integration has many potential steps that can be inhibited and several new compounds that target specific integration steps have been identified by drug developers. Recently, two INIs, GS-9137 and MK-0518, demonstrated promising early clinical trial results and have been advanced into later stage trials. In this review, we describe how IN facilitates HIV-1 integration, the needed enzyme cofactors, and the resultant byproducts created during integration. Furthermore, we review the different INIs under development, their mechanism of actions, site of IN inhibition, potency, resistance patterns, and discuss the early clinical trial results.

Drug Design↗

Design, synthesis and biological evaluation of heteroaryl diketohexenoic and diketobutanoic acids as HIV-1 integrase inhibitors endowed with antiretroviral activity.

Highly active anti-retroviral therapy (HAART) using reverse transcriptase (RT) and protease (PR) inhibitors and, more recently, inhibitors of the fusion is currently the best clinical approach in combating acquired immunodeficiency syndrome (AIDS), caused by infection from human immunodeficiency virus type 1 (HIV-1). However, this therapy does not completely eradicate the virus, so that resistant strains easily emerge. The above problem calls urgently for research on inhibitors of further viral targets such as integrase (IN), the third enzyme produced by HIV. Recently, our research group was engaged in studies on conformationally restrained cinnamoyl compounds related to curcumin as anti-IN agents. Compounds containing both a 3,4,5-trihydroxyphenyl group and a carboxylic acid function were potent IN inhibitors active against viral replication. More recently, a promising new class of inhibitors synthesized by Merck Company has emerged, which contain aryldiketoacid (ADK) functionality. The ADKs selectively inhibited the stand transfer (ST) step of integration and were proven to be effective IN inhibitors in vivo. Our interest in the field of IN inhibitors led us to design pyrrole and indole derivatives containing both a cinnamoyl moiety and a diketoacid group. A number of the cited derivatives were proven potent IN inhibitors, which selectively inhibited the ST step at submicromolar concentrations and were effective against virus replication in HIV-1 infected cells.

Anti-Retroviral Agents↗