Quinolinonyl derivatives as dual inhibitors of the HIV-1 integrase catalytic site and integrase-RNA interactions.

Over the past three decades, the outcome of HIV infection has been revolutionized by considerable progress in the therapeutic options available, as a result of the introduction of effective multi-pills regimens (ART). Although ART is purposely devised to overcome the high viral genetic variability and the subsequent emergence of resistance, multi-drug resistant strains can still be detected in some patients and long-term drug toxicities still represent an unresolved concern in HIV management. HIV integrase (IN) is vital for viral replication and it is an important therapeutic target. In this regard, integrase strand transfer inhibitors (INSTIs) which bind to the active site of the viral enzyme, have proven to be highly effective, becoming a potent first-line therapy to treat infected patients. However, despite the effectiveness of INSTIs as therapeutic options and the high barriers with the second-generation FDA- approved INSTIs, the pharmacological therapy selects for drug resistance and mutations responsible for multiple INSTIs resistance have been described in clinical practice, underscoring the need for the development of novel and more effective antiretroviral compounds. The development of small molecule protein-protein interaction inhibitors is a new attractive strategy for discovering anti-HIV agents. In this field of research, allosteric IN inhibitors (ALLINIs), are a promising new class of antiretroviral agents. These inhibitors act differently in respect to INSTIs, in fact, they alter the functional IN multimerization. Recently, it was unraveled that aberrant IN multimerization underlies the inhibition of IN-vRNA interactions by ALLINIs. In doing so, ALLINIs indirectly disrupt the IN-vRNA binding leading, as a result, to the formation of defective viral particles with greatly reduced infective potential with mis-localization of the vRNA outside the viral capsid. While the indirect disruption of IN-vRNA binding (caused by the impairment of functional IN multimerization) has been described with the treatment of virus-producing cells with ALLINIs, the direct disruption of this binding (without affecting IN multimerization properties) by small molecules has not been reported so far. We describe a series of compounds identified as inhibitors of the IN-vRNA binding via a direct mechanism. In particular, we deepened the mechanism of action of some compounds previously described by us as INSTIs. Indeed, we speculated that these quinolinonyl derivatives, being endowed with two DKA chains, could also act as protein-nucleic acid interaction inhibitors. To verify our hypothesis, we decided to test a set of derivatives and their analogues endowed with a variable “base-like” functional group. We assessed the capability of our derivatives of inhibiting at low micromolar concentrations both the IN 3’-processing (3’-P) and strand transfer (ST) reactions in a LEDGF/p75 independent assay. In addition, we performed in vitro binding assays, and we found that our quinolinonyl derivatives are able to disrupt the IN-vRNA interaction, that is vital for a correct generation of a functional infective virion. The data coming from the biological assays will be shown and discussed.