Helena de Souza Pereira

Synthesis of novel nucleosides of 4‐oxoquinoline‐3‐carboxylic acid analogues

A series of new ribonucleosides 1a–d having 4-oxoquinoline-3-carboxylic acid substituted with a chloro or bromo atom in the aromatic ring, as the nitrogen base, was synthesized and examined for anti-HIV activity. Compounds 1a and 1c showed a modest inhibition activity on HIV-1 reverse transcriptase, inhibiting 10% of the enzyme activity at the concentration of 100 μM.

Development of a New Methodology for Screening of Human Immunodeficiency Virus Type 1 Microbicides Based on Real-Time PCR Quantification

ABSTRACT Potential topical retrovirucides or vaginal microbicides against human immunodeficiency virus type 1 (HIV-1) include nonnucleoside reverse transcriptase inhibitors (NNRTIs). To be successful, such agents have to be highly active against cell-free virions. In the present study, we developed a new real-time PCR-based assay to measure the natural endogenous reverse transcription (NERT) activity directly on intact HIV-1 particles in the presence of reverse transcriptase (RT) inhibitors. We further evaluated the permeability to nevirapine (NVP) and efavirenz (EFV) and their retention within nascent viral particles. We also demonstrated the NVP and EFV inhibitory effects on NERT activity and the impact of resistance mutations measured directly by this new strategy. Furthermore, the results showed a clear correlation between NERT activity and classical infectivity assays. The 50% inhibitory concentrations (IC50s) of NVP and EFV were demonstrated to be up to 100-fold higher for cell-free than for cell-associated virions, suggesting that cell-free virions are less permeable to these drugs. Our results suggest that NVP and EFV penetrate both the envelope and the capsid of HIV-1 particles and readily inactivate cell-free virions. However, the characteristics of these NNRTIs, such as lower permeability and lower retention during washing procedures, in cell-free virions reduce their efficacies as microbicides. Here, we demonstrate the usefulness of the NERT real-time PCR as an assay for screening novel antiretroviral compounds with unique mechanisms of action.

Anti-HIV-1 activity in human primary cells and Anti-HIV-1 RT inhibitory activity of extracts from the red seaweed Acanthophora spicifera

First generation drugs such as zidovudine have been extensively used in clinical practice, resulting in the development of HIV resistance to these nucleoside analogs. Several studies have demonstrated the effective anti-HIV activity of natural products derived from seaweeds, suggesting promising sources of substances for the development of novel antiviral drugs. In this paper, the antiviral effect of extracts from the red seaweed Acanthophora spicifera on HIV-1 replication was evaluated in vitro. Peripheral blood mononuclear cells obtained using the Ficoll-Hypaque gradient were used for cytotoxicity and antiviral activity testing. The dichloromethane extracts, ethyl acetate, acetone, and methanol were found to have CC50 values of 31±7.4, 45±11, 38±3.5, and 179±25 µg/mL, respectively. With the control, the extract prepared in ethyl acetate inhibited approximately 60% of the viral load, which is the best result among the extracts. This same extract showed an IC50 value of 33.17±4.84 μg/mL for the reverse transcriptase. The EtOAc extract from A. spicifera showed to be an efficient HIV antiviral due to its phenolic compounds, as evaluated by nuclear magnetic resonance. Key words: Marine natural products, red seaweed, Acanthophora spicifera, HIV-1, Antiviral activity, Anti-HIV-1 RT.