Lucas V. B. Hoelz

The clinically approved antiviral drug sofosbuvir inhibits Zika virus replication.

Zika virus (ZIKV) is a member of the Flaviviridae family, along with other agents of clinical significance such as dengue (DENV) and hepatitis C (HCV) viruses. Since ZIKV causes neurological disorders during fetal development and in adulthood, antiviral drugs are necessary. Sofosbuvir is clinically approved for use against HCV and targets the protein that is most conserved among the members of the Flaviviridae family, the viral RNA polymerase. Indeed, we found that sofosbuvir inhibits ZIKV RNA polymerase, targeting conserved amino acid residues. Sofosbuvir inhibited ZIKV replication in different cellular systems, such as hepatoma (Huh-7) cells, neuroblastoma (SH-Sy5y) cells, neural stem cells (NSC) and brain organoids. In addition to the direct inhibition of the viral RNA polymerase, we observed that sofosbuvir also induced an increase in A-to-G mutations in the viral genome. Together, our data highlight a potential secondary use of sofosbuvir, an anti-HCV drug, against ZIKV.

Structural and Functional Analysis of a Platelet-Activating Lysophosphatidylcholine of Trypanosoma cruzi

Background Trypanosoma cruzi is the causative agent of the life-threatening Chagas disease, in which increased platelet aggregation related to myocarditis is observed. Platelet-activating factor (PAF) is a potent intercellular lipid mediator and second messenger that exerts its activity through a PAF-specific receptor (PAFR). Previous data from our group suggested that T. cruzi synthesizes a phospholipid with PAF-like activity. The structure of T. cruzi PAF-like molecule, however, remains elusive. Methodology/Principal findings Here, we have purified and structurally characterized the putative T. cruzi PAF-like molecule by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Our ESI-MS/MS data demonstrated that the T. cruzi PAF-like molecule is actually a lysophosphatidylcholine (LPC), namely sn-1 C18:1(delta 9)-LPC. Similar to PAF, the platelet-aggregating activity of C18:1-LPC was abrogated by the PAFR antagonist, WEB 2086. Other major LPC species, i.e., C16:0-, C18:0-, and C18:2-LPC, were also characterized in all T. cruzi stages. These LPC species, however, failed to induce platelet aggregation. Quantification of T. cruzi LPC species by ESI-MS revealed that intracellular amastigote and trypomastigote forms have much higher levels of C18:1-LPC than epimastigote and metacyclic trypomastigote forms. C18:1-LPC was also found to be secreted by the parasite in extracellular vesicles (EV) and an EV-free fraction. A three-dimensional model of PAFR was constructed and a molecular docking study was performed to predict the interactions between the PAFR model and PAF, and each LPC species. Molecular docking data suggested that, contrary to other LPC species analyzed, C18:1-LPC is predicted to interact with the PAFR model in a fashion similar to PAF. Conclusions/Significance Taken together, our data indicate that T. cruzi synthesizes a bioactive C18:1-LPC, which aggregates platelets via PAFR. We propose that C18:1-LPC might be an important lipid mediator in the progression of Chagas disease and its biosynthesis could eventually be exploited as a potential target for new therapeutic interventions.

Dynamical behaviour of the human β1-adrenoceptor under agonist binding

The human β1-adrenoceptor (hβ1AR) is a transmembrane (TM) protein responsible for the signal transduction pathway via agonist interaction. Despite its importance, hβ1AR activation mechanism is still unclear. The most studied and widely accepted mechanism is the disruption of a salt bridge between TM3 arginine and TM6 glutamic acid, called ionic lock. In this work, we constructed a functional hβ1AR-model equilibrated in a membrane environment to study the influence of agonist binding on the dynamical behaviour of hβ1AR and on the opening of the ionic lock. The results indicate that the agonist (R-noradrenaline) disturbs the hβ1AR, causing a TM helices rotation, disrupting the ionic lock. This rotational motion occurs in opposite directions in the intercellular and extracellular domains of hβ1AR, opening the ionic lock.

Solvent free, microwave assisted conversion of aldehydes into nitriles and oximes in the presence of NH2OH x HCl and TiO2.

Aromatic aldehydes bearing electron-donating groups are easily converted into their respective nitriles using NH2OH·HCl and TiO2 under microwave irradiation, while those bearing an electron-withdrawing group give the corresponding oximes.

The role of helices 5 and 6 on the human β1-adrenoceptor activation mechanism

The human β1-adrenoceptor (β1AR) is a G-protein-coupled receptor (GPCR) involved in sympathetic system regulation through agonist-induced activation. The conserved CWXP-motif in helix 6 (rotamer toggle switch) is one of the most important activation switches in Class A GPCRs. In order to investigate how the agonist binding disturbs this switch, we carried out molecular dynamics simulations of a hβ1AR model in the apo and R-noradrenaline-bound forms. The results show that the agonist binding changes the β1-angle distribution of Cys336, Trp337 and Phe341 residues and increases the helix 6 bending. Overall, we provide a functional hβ1AR model, showing how the rotamer toggle switch mechanism works at atomic level.

CoMFA/CoMSIA 3D-QSAR of pyrimidine inhibitors of Pneumocystis carinii dihydrofolate reductase

AbstractPneumocystis carinii is typically a non-pathogenic fungus found in the respiratory tract of healthy humans. However, it may cause P. carinii pneumonia (PCP) in people with immune deficiency, affecting mainly premature babies, cancer patients and transplant recipients, and people with acquired immunodeficiency syndrome (AIDS). In the latter group, PCP occurs in approximately 80% of patients, a major cause of death. Currently, there are many available therapies to treat PCP patients, including P. carinii dihydrofolate reductase (PcDHFR) inhibitors, such as trimetrexate (TMX), piritrexim (PTX), trimethoprim (TMP), and pyrimethamine (PMT). Nevertheless, the high percentage of adverse side effects and the limited therapeutic success of the current drug therapy justify the search for new drugs rationally planned against PCP. This work focuses on the study of pyrimidine inhibitors of PcDHFR, using both CoMFA and CoMSIA 3D-QSAR methods. FigureCoMFA/CoMSIA 3D-QSAR of pyrimidine inhibitors of Pneumocystis carinii dihydrofolate reductase

Quimioterapia Antileishmania: Uma Revisão da Literatura

According to the World Health Organization (WHO), leishmaniasis is one of the major tropical diseases. There are four clinical manifestations of this illness and the most severe form, sometimes lethal, is the visceral leishmaniasis (VL). To date, there is no effective vaccine available, being the chemotherapy the only way to treat this disease, although it presents serious limitations. Several strategies have been employed to improve the leishmaniasis treatment, among them, the use of drug combinations and the development of new drugs. The success in development of new antileishmanial agents depends on the knowledge of the Medicinal Chemistry related to the current treatments in use. For this reason, this review aims to analyze the current drugs, through the concepts of Medicinal Chemistry and the synthetic processes.

Corrigendum: The clinically approved antiviral drug sofosbuvir inhibits Zika virus replication

Scientific Reports 7: Article number: 40920; published online 18 January 2017; updated on 24 April 2017 The Competing Financial Interests section in this Article is incorrect and should read: “Dr. Karin Bruning is a member of the BMK consortium, able to produce sofosbuvir”.

VEGF system, a multi therapeutic target

The ability to modulate the vascular endothelial growth factor system (VEGF) is fundamental in the treatment of several pathophysiologies and in the maintenance of homeostasis. Here, some strategies of control are discussed, e.g. extracellular actions, monoclonal antibodies and aptamers acting as inhibitors of VEGF and its receptors (VEGFR). In addition, in the cytoplasm one must include inhibitors of the tyrosine kinase domain.