5,6-Dihydroxypyrimidine Scaffold to Target HIV-1 Nucleocapsid Protein.

The HIV-1 nucleocapsid (NC) protein is a small basic DNA and RNA binding protein that is absolutely necessary for viral replication and thus represents a target of great interest to develop new anti-HIV agents. Moreover, the highly conserved sequence offers the opportunity to escape the drug resistance (DR) that emerged following the highly active antiretroviral therapy (HAART) treatment. On the basis of our previous research, nordihydroguaiaretic acid 1 acts as a NC inhibitor showing moderate antiviral activity and suboptimal drug-like properties due to the presence of the catechol moieties. A bioisosteric catechol replacement approach led us to identify the 5-dihydroxypyrimidine-6-carboxamide substructure as a privileged scaffold of a new class of HIV-1 NC inhibitors. Hit validation efforts led to the identification of optimized analogs, as represented by compound 28, showing improved NC inhibition and antiviral activity as well as good ADME and PK properties.

Synthesis and Evaluation of Bifunctional Aminothiazoles as Antiretrovirals Targeting the HIV-1 Nucleocapsid Protein.

Small molecule inhibitors of the HIV-1 nucleocapsid protein (NC) are considered as promising agents in the treatment of HIV/AIDS. In an effort to exploit the privileged 2-amino-4-phenylthiazole moiety in NC inhibition, here we conceived, synthesized, and tested in vitro 18 NC inhibitors (NCIs) bearing a double functionalization. In these NCIs, one part of the molecule is deputed to interact noncovalently with the NC hydrophobic pocket, while the second portion is designed to interact with the N-terminal domain of NC. This binding hypothesis was verified by molecular dynamics simulations, while the linkage between these two pharmacophores was found to enhance antiretroviral activity both on the wild-type virus and on HIV-1 strains with resistance to currently licensed drugs. The two most interesting compounds 6 and 13 showed no cytotoxicity, thus becoming valuable leads for further investigations.

Structure-Based Identification of HIV-1 Nucleocapsid Protein Inhibitors Active against Wild-Type and Drug-Resistant HIV-1 Strains.

HIV/AIDS is still one of the leading causes of death worldwide. Current drugs that target the canonical steps of the HIV-1 life cycle are efficient in blocking viral replication but are unable to eradicate HIV-1 from infected patients. Moreover, drug resistance (DR) is often associated with the clinical use of these molecules, thus raising the need for novel drug candidates as well as novel putative drug targets. In this respect, pharmacological inhibition of the highly conserved and multifunctional nucleocapsid protein (NC) of HIV-1 is considered a promising alternative to current drugs, particularly to overcome DR. Here, using a multidisciplinary approach combining in silico screening, fluorescence-based molecular assays, and cellular antiviral assays, we identified nordihydroguaiaretic acid (6), as a novel natural product inhibitor of NC. By using NMR, mass spectrometry, fluorescence spectroscopy, and molecular modeling, 6 was found to act through a dual mechanism of action never highlighted before for NC inhibitors (NCIs). First, the molecule recognizes and binds NC noncovalently, which results in the inhibition of the nucleic acid chaperone properties of NC. In a second step, chemical oxidation of 6 induces a potent chemical inactivation of the protein. Overall, 6 inhibits NC and the replication of wild-type and drug-resistant HIV-1 strains in the low micromolar range with moderate cytotoxicity that makes it a profitable tool compound as well as a good starting point for the development of pharmacologically relevant NCIs.

Insights into the interaction of high potency inhibitor IRC-083864 with phosphatase CDC25.

CDC25 phosphatases play a crucial role in cell cycle regulation. They have been found to be over-expressed in various human tumours and to be valuable targets for cancer treatment. Here, we report the first model of binding of the most potent CDC25 inhibitor to date, the bis-quinone IRC-083864, into CDC25B obtained by combining molecular modeling and NMR studies. Our study provides new insights into key interactions of the catalytic site inhibitor and CDC25B in the absence of any available experimental structure of CDC25 with a bound catalytic site inhibitor. The docking model reveals that IRC-083864 occupies both the active site and the inhibitor binding pocket of the CDC25B catalytic domain. NMR saturation transfer difference and WaterLOGSY data indicate the binding zones of the inhibitor and support the docking model. Probing interactions of analogues of the two quinone units of IRC-083864 with CDC25B demonstrate that IRC-083864 competes with each monomer. Proteins 2017; 85:593-601. © 2016 Wiley Periodicals, Inc.

Development and in Vitro Evaluation of a Microbicide Gel Formulation for a Novel Non-Nucleoside Reverse Transcriptase Inhibitor Belonging to the N-Dihydroalkyloxybenzyloxopyrimidines (N-DABOs) Family.

Preventing HIV transmission by the use of a vaginal microbicide is a topic of considerable interest in the fight against AIDS. Both a potent anti-HIV agent and an efficient formulation are required to develop a successful microbicide. In this regard, molecules able to inhibit the HIV replication before the integration of the viral DNA into the genetic material of the host cells, such as entry inhibitors or reverse transcriptase inhibitors (RTIs), are ideal candidates for prevention purpose. Among RTIs, S- and N-dihydroalkyloxybenzyloxopyrimidines (S-DABOs and N-DABOs) are interesting compounds active at nanomolar concentration against wild type of RT and with a very interesting activity against RT mutations. Herein, novel N-DABOs were synthesized and tested as anti-HIV agents. Furthermore, their mode of binding was studied by molecular modeling. At the same time, a vaginal microbicide gel formulation was developed and tested for one of the most promising candidates.

Synthesis of linear and cyclic guazatine derivatives endowed with antibacterial activity.

Antibiotic resistance has reached alarming levels in many clinically-relevant human pathogens, and there is an increasing clinical need for new antibiotics active on drug-resistant Gram-negative pathogens who rapidly evolve towards pandrug resistance phenotypes. Here, we report on two related classes of guanidinic compounds endowed with antibacterial activity. The two best compounds (9a and 13d) exhibited the most potent antibacterial activity with MIC values ranging 0.12-8 µg/ml with most tested pathogens, including both Gram-positive and Gram-negative bacteria. Interestingly, MIC values were not affected (1-8 µg/ml) when measured using recent clinical isolates with various antibiotic resistance determinants. The results reported herein identify guazatine derivatives as an interesting starting point for the optimization of a potentially novel class of antibacterial agents.