Inhibition of HIV-1 nuclear import via schiff base formation with arylene bis(methylketone) compounds

Synthesis, biological evaluation of antioxidant-antibacterial activities and computational studies of novel anthracene- and pyrene-based Schiff base derivatives

Schiff base derivatives with anthracene- and pyrene-based units, A1-A6 and P1-P6 were synthesized (89%–99% yields). Schiff base derivatives were designed to possess an heterocyclic moiety on one side to enhance the coordination ability towards metals. To investigate the biological assay of the newly synthesized compounds, their DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, metal chelating, reducing power, antibacterial and DNA binding activities were tested. A6 (63.1%) showed the maximum free radical scavenging activity among all. However, compound P3 at concentration of 200 μg/mL possessed the highest metal chelating (45.8%) activity and power of reduction. In addition, P3 and A6 showed antibacterial activity against all bacteria tested and both compounds were very well bound to CT-DNA. Density functional theory method with B3LYP/6-311++G(d,p) basis set was performed to get information about the structural and electronic properties of the present compounds. In addition, the metal coordination properties of the dimers of the parent Schiff bases were investigated through interactions with Zn²⁺.

SJP-L-5, a novel small-molecule compound, inhibits HIV-1 infection by blocking viral DNA nuclear entry

Background

Small-molecule compounds that inhibit human immunodeficiency virus type 1 (HIV-1) infection can be used not only as drug candidates, but also as reagents to dissect the life cycle of the virus. Thus, it is desirable to have an arsenal of such compounds that inhibit HIV-1 infection by various mechanisms. Until now, only a few small-molecule compounds that inhibit nuclear entry of viral DNA have been documented.

Results

We identified a novel, small-molecule compound, SJP-L-5, that inhibits HIV-1 infection. SJP-L-5 is a nitrogen-containing, biphenyl compound whose synthesis was based on the dibenzocyclooctadiene lignan gomisin M2, an anti-HIV bioactive compound isolated from Schisandra micrantha A. C. Smith. SJP-L-5 displayed relatively low cytotoxicity (50 % cytoxicity concentrations were greater than 200 μg/ml) and high antiviral activity against a variety of HIV strains (50 % effective concentrations (EC₅₀)) of HIV-1 laboratory-adapted strains ranged from 0.16–0.97 μg/ml; EC₅₀s of primary isolates ranged from 1.96–5.33 μg/ml). Analyses of the viral DNA synthesis indicated that SJP-L-5 specifically blocks the entry of the HIV-1 pre-integration complex (PIC) into the nucleus. Further results implicated that SJP-L-5 inhibits the disassembly of HIV-1 particulate capsid in the cytoplasm of the infected cells.

Conclusions

SJP-L-5 is a novel small-molecule compound that inhibits HIV-1 nuclear entry by blocking the disassembly of the viral core.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-015-0605-3) contains supplementary material, which is available to authorized users.

Nuclear translocation as a novel target for anti-HIV drugs

During recent years, remarkable progress has been achieved in the treatment of patients infected with HIV. This progress involves not only the improvement of previously known drugs but also the introduction of new classes of anti-HIV agents. Currently, drugs targeting virus entry, reverse transcription, integration and maturation are either in clinical use or in the late stages of clinical development. Nonetheless, the high mutation rate of the virus and toxicity of the drugs, which become problematic during prolonged treatment regimens characteristic of anti-HIV therapy, drive the necessity to produce new drugs that will allow physicians to keep the virus at bay in patients on lifelong anti-HIV therapy. Ideally, such drugs would target a new step in the HIV life cycle, thus avoiding crossresistance with older compounds. One such new target for anti-HIV therapy is nuclear translocation--a process critical for HIV replication. In this article, the authors will review recent literature on the mechanisms of HIV nuclear import and will describe compounds that inhibit this step of HIV replication.

Pharmacological inhibition of feline immunodeficiency virus (FIV)

Feline immunodeficiency virus (FIV) is a member of the retroviridae family of viruses and causes an acquired immunodeficiency syndrome (AIDS) in domestic and non-domestic cats worldwide. Genome organization of FIV and clinical characteristics of the disease caused by the virus are similar to those of human immunodeficiency virus (HIV). Both viruses infect T lymphocytes, monocytes and macrophages, and their replication cycle in infected cells is analogous. Due to marked similarity in genomic organization, virus structure, virus replication and disease pathogenesis of FIV and HIV, infection of cats with FIV is a useful tool to study and develop novel drugs and vaccines for HIV. Anti-retroviral drugs studied extensively in HIV infection have targeted different steps of the virus replication cycle: (1) inhibition of virus entry into susceptible cells at the level of attachment to host cell surface receptors and co-receptors; (2) inhibition of fusion of the virus membrane with the cell membrane; (3) blockade of reverse transcription of viral genomic RNA; (4) interruption of nuclear translocation and viral DNA integration into host genomes; (5) prevention of viral transcript processing and nuclear export; and (6) inhibition of virion assembly and maturation. Despite much success of anti-retroviral therapy slowing disease progression in people, similar therapy has not been thoroughly investigated in cats. In this article we review current pharmacological approaches and novel targets for anti-lentiviral therapy, and critically assess potentially suitable applications against FIV infection in cats.

Strategies to inhibit viral protein nuclear import: HIV-1 as a target

Nuclear import is a critical step in the life cycle of HIV-1. During the early (preintegration) stages of infection, HIV-1 has to transport its preintegration complex into the nucleus for integration into the host cell chromatin, while at the later (postintegration) stages viral regulatory proteins Tat and Rev need to get into the nucleus to stimulate transcription and regulate splicing and nuclear export of subgenomic and genomic RNAs. Given such important role of nuclear import in HIV-1 life cycle, this step presents an attractive target for antiviral therapeutic intervention. In this review, we describe the current state of our understanding of the interactions regulating nuclear import of the HIV-1 preintegration complex and describe current approaches to inhibit it. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import.

Interactions of human cytomegalovirus proteins with the nuclear transport machinery

Accurate cellular localization is crucial for the effective function of most viral macromolecules and nuclear translocation is central to the function of herpesviral proteins that are involved in processes such as transcription and DNA replication. The passage of large molecules between the cytoplasm and nucleus, however, is restricted, and this restriction affords specific mechanisms that control nucleocytoplasmic exchange. In this review, we focus on two cytomegalovirus-encoded proteins, pUL69 and pUL84, that are able to shuttle between the nucleus and the cytoplasm. Both viral proteins use unconventional interactions with components of the cellular transport machinery: pUL69 binds to the mRNA export factor UAP56, and this interaction is crucial for pUL69-mediated nuclear export of unspliced RNA; pUL84 docks to importin-alpha proteins via an unusually large protein domain that contains functional leucine-rich nuclear export signals, thus serving as a complex bidirectional transport domain. Selective interference with these unconventional interactions, which disturbs the intracellular trafficking of important viral regulatory proteins, may constitute a novel and attractive principle for antiviral therapy.

Oxadiazols: a new class of rationally designed anti-human immunodeficiency virus compounds targeting the nuclear localization signal of the viral matrix protein

Despite recent progress in anti-human immunodeficiency virus (HIV) therapy, drug toxicity and emergence of drug-resistant isolates during long-term treatment of HIV-infected patients necessitate the search for new targets that can be used to develop novel antiviral agents. One such target is the process of nuclear translocation of the HIV preintegration complex. Previously we described a class of arylene bis(methylketone) compounds that inhibit HIV-1 nuclear import by targeting the nuclear localization signal (NLS) in the matrix protein (MA). Here we report a different class of MA NLS-targeting compounds that was selected using computer-assisted drug design. The leading compound from this group, ITI-367, showed potent anti-HIV activity in cultures of T lymphocytes and macrophages and also inhibited HIV-1 replication in ex vivo cultured lymphoid tissue. The virus carrying inactivating mutations in MA NLS was resistant to ITI-367. Analysis by real-time PCR demonstrated that the compound specifically inhibited nuclear import of viral DNA, measured by two-long terminal repeat circle formation. Evidence of the existence of this mechanism was provided by immunofluorescent microscopy, using fluorescently labeled HIV-1, which demonstrated retention of the viral DNA in the cytoplasm of drug-treated macrophages. Compounds inhibiting HIV-1 nuclear import may be attractive candidates for further development.