Novel quinolinonyl diketo acid derivatives as HIV-1 integrase inhibitors: design, synthesis, and biological activities.

Novel quinolinonyl diketo acids were designed to obtain integrase (IN) inhibitors selectively active against the strand transfer (ST) step of the HIV integration process. Those new compounds are characterized by a single aryl diketo acid (DKA) chain in comparison to 4, a bifunctional diketo acid reported by our group as an anti-IN agent highly potent against both the 3'-processing and ST steps. Compound 6d was the most potent derivative in IN enzyme assays, while 6i showed the highest potency against HIV-1 in acutely infected cells. The selective inhibition of ST suggested the newly designed monofunctional DKAs bind the IN-DNA acceptor site without affecting the DNA donor site.

Development of a human immunodeficiency virus vector-based, single-cycle assay for evaluation of anti-integrase compounds.

Therapeutic strategies aimed at inhibiting human immunodeficiency virus type 1 (HIV-1) replication employ a combination of drugs targeted to two viral enzymes (reverse transcriptase and protease) and to the viral entry/fusion step. However, the high propensity of HIV-1 to develop resistance makes the development of novel compounds targeting different steps of the HIV-1 life cycle essential. Among these, integrase (IN) inhibitors have successfully passed the early phases of clinical development. By preventing integration, IN inhibitors preclude viral replication while allowing production of extrachromosomal forms of viral DNA (E-DNA). Here, we describe an improved and standardized assay aimed at evaluating IN inhibitors by taking advantage of the transcriptional activity of E-DNA produced by HIV-derived vectors in the absence of replication-competent virus. In this context, the use of the firefly luciferase gene as a reporter gene provides a rapid and quantitative measure of viral-vector infectivity, thus making it a safe and cost-effective assay for evaluating novel IN inhibitors.

Novel bifunctional quinolonyl diketo acid derivatives as HIV-1 integrase inhibitors: design, synthesis, biological activities, and mechanism of action.

The virally encoded integrase protein is an essential enzyme in the life cycle of the HIV-1 virus and represents an attractive and validated target in the development of therapeutics against HIV infection. Drugs that selectively inhibit this enzyme, when used in combination with inhibitors of reverse transcriptase and protease, are believed to be highly effective in suppressing the viral replication. Among the HIV-1 integrase inhibitors, the beta-diketo acids (DKAs) represent a major lead for anti-HIV-1 drug development. In this study, novel bifunctional quinolonyl diketo acid derivatives were designed, synthesized, and tested for their inhibitory ability against HIV-1 integrase. The compounds are potent inhibitors of integrase activity. Particularly, derivative 8 is a potent IN inhibitor for both steps of the reaction (3'-processing and strand transfer) and exhibits both high antiviral activity against HIV-1 infected cells and low cytotoxicity. Molecular modeling studies provide a plausible mechanism of action, which is consistent with ligand SARs and enzyme photo-cross-linking experiments.

Simple but highly effective three-dimensional chemical-feature-based pharmacophore model for diketo acid derivatives as hepatitis C virus RNA-dependent RNA polymerase inhibitors.

A molecular modeling strategy using aryl diketo acid (ADK) derivatives recently reported in the literature as hepatitis C virus (HCV) polymerase inhibitors was designed. A 3D chemical-feature-based pharmacophore model was developed using Catalyst software, which produced 10 pharmacophore hypotheses. The top-ranked one (Hypo 1), characterized by a high correlation coefficient (r = 0.965), consisted of two hydrogen bond acceptors, one negative ionizable moiety, and two hydrophobic aromatics. This model was used to predict the anti-RNA-dependent RNA polymerase (anti-RdRp) activity of 6-(1-arylmethylpyrrol-2-yl)-1,4-dioxo-5-hexenoic acids and other ADK derivatives previously synthesized in our laboratories as HIV-1 integrase inhibitors. Furthermore, the experimental IC50 values of 9 compounds, tested in vitro against recombinant HCV polymerase, were compared with the corresponding values predicted using Hypo1. A good agreement between experimental and simulated data was obtained. The results demonstrate that the hypothesis derived in this study can be considered to be a useful tool in designing new leads based on ADK scaffolds as HCV RdRp inhibitors.

Design, synthesis, and biological activities of pyrrolylethanoneamine derivatives, a novel class of monoamine oxidases inhibitors.

Pyrrolylethanoneamines 1-12, 18-23 and related amino alcohols 13-15, 24-27 were synthesized and tested against monoamine oxidases A and B (MAO-A and MAO-B) enzymes. In general, aminoketones 1-12, 18-23 were found to be potent and selective MAO-A inhibitors. In particular, 18 was more potent and selective against the MAO-A isoenzyme than reference drugs. Interestingly, amino alcohol 25 selectively inhibited MAO-B enzyme and could be a lead compound for designing more potent and selective MAO-B inhibitors.

Diketo hexenoic acid derivatives are novel selective non-nucleoside inhibitors of mammalian terminal deoxynucleotidyl transferases, with potent cytotoxic effect against leukemic cells.

Mammalian terminal deoxyribonucleotidyl transferase (TDT) catalyzes the non-template-directed polymerization of deoxyribonucleoside triphosphates and has a key role in V(D)J recombination during lymphocyte and repertoire development. More than 90% of leukemic cells in acute lymphocytic leukemia and approximately 30% of leukemic cells in the chronic myelogenous leukemia crisis show elevated TDT activity. This finding is connected to a poor prognosis and response to chemotherapy and reduced survival time. On the other hand, recent data indicated that TDT is not the only terminal deoxyribonucleotidyl transferase in mammalian cells. Its close relative, DNA polymerase lambda, can synthesize DNA both in a template-dependent (polymerase) and template-independent (terminal deoxyribonucleotidyl transferase) fashion. DNA polymerase lambda might be involved in the nonhomologous end-joining recombinational repair pathway of DNA double-strand breaks. In this work, we report the characterization of the mechanism of action of three diketo hexenoic acid (DKHA) derivatives, which proved to be extremely selective for the terminal deoxyribonucleotidyl transferase activity of DNA polymerase lambda and TDT. They seem to be the first non-nucleoside-specific inhibitors of mammalian terminal transferases reported. Moreover, the DKHA analog 6-(1-phenylmethyl-1H-indol-3-yl)-2,4-dioxo-5-hexenoic acid (RDS2119) was not toxic toward HeLa cells (CC(50) > 100 muM), whereas it showed significant cytotoxicity against the TDT(+) leukemia cell line MOLT-4 (CC(50) = 14.9 muM), thus having the potential to be further developed as a novel antitumor agent.

6-aryl-2,4-dioxo-5-hexenoic acids, novel integrase inhibitors active against HIV-1 multiplication in cell-based assays.

A series of 6-aryl-2,4-dioxo-5-hexenoic acids, were synthesized and tested against HIV-1 in cell-based assays and against recombinant HIV-1 integrase (rIN) in enzyme assays. Compound 8a showed potent antiretroviral activity (EC(50)=1.5 microM) and significant inhibition against rIN (strand transfer: IC(50)=7.9 microM; 3'-processing: IC(50)=7.0 microM). A preliminary molecular modeling study was carried out to compare the spatial conformation of 8a with those of L-731988 (4) and 5CITEP (7) in the IN core.