Knock-out of multidrug efflux pump MexXY-OprM results in increased susceptibility to antimicrobial peptides in Pseudomonas aeruginosa.

Multidrug efflux systems of the resistance-nodulation-cell division family play a crucial role in resistance of Pseudomonas aeruginosa to a large variety of antibiotics. Here, we investigated the role of clinically relevant efflux pumps MexAB- OprM, MexCD- OprJ, and MexXY- OprM in resistance against different cationic antimicrobial peptides (AMPs). Our results indicate that a knock-out in efflux pump MexXY-OprM increased susceptibility to some AMPs by two- to eightfold. Our data suggest a contribution of MexXY-OprM in resistance to certain AMPs in P. aeruginosa, which should be considered in the future development of new and highly active antimicrobial peptides to fight multidrug resistant infections.

Virucidal antiviral activity of Maytenus quadrangulata extract against Mayaro virus: Evidence for the presence of catechins.

ETHNOPHARMACOLOGICAL RELEVANCE: Mayaro virus (MAYV) is an arbovirus endemic to the Amazon region, which comprises the states of the North and Midwest region of Brazil and encompasses the largest tropical forest in the world, the Amazon Forest. The confirmation of its potential transmission by Aedes aegypti and recent cases in Brazil, mainly in large centers in the northern region, led to the classification of Mayaro fever as an emerging disease. Traditional medicine is commonly used to treat various diseases, mainly by local riverside populations. Some species of the genus Maytenus, which have similar morphologies, are popularly used to treat infections and inflammations. In this context, our research group has studied and confirmed the antiviral activity of several plant-derived compounds. However, several species of this same genus have not been studied and therefore deserve attention. AIM OF THE STUDY: This study aimed to demonstrate the effects of ethyl acetate extracts of leaves (LAE) and branches (TAE) of Maytenus quadrangulata against MAYV. MATERIALS AND METHODS: Mammalian cells (Vero cells) were used to evaluate the cytotoxicity of the extracts. After cell infection by MAYV and the treatment with the extracts, we evaluated the selectivity index (SI), the virucidal effect, viral adsorption and internalization, and the effect on viral gene expression. The antiviral action was confirmed by quantifying the viral genome using RT-qPCR and by analyzing the effect on virus yield in infected cells. The treatment was performed based on the effective concentration protective for 50% of the infected cells (EC50). RESULTS: The leaves (LAE; EC50 12.0 µg/mL) and branches (TAE; EC50 101.0 µg/mL) extracts showed significative selectivity against the virus, with SI values of 79.21 and 9.91, respectively, which were considered safe. Phytochemical analysis revealed that the antiviral action was associated with the presence of catechins, mainly in LAE. This extract was chosen for the subsequent studies since it reduced the viral cytopathic effect and virus production, even at high viral loads [MOI (multiplicity of infection) 1 and 5]. The effects of LAE resulted in a marked reduction in viral gene expression. The viral title was drastically reduced when LAE was added to the virus before infection or during replication stages, reducing virus production up to 5-log units compared to infected and untreated cells. CONCLUSION: Through kinetic replication, MAYV was not detected in Vero cells treated with LAE throughout the viral cycle. The virucidal effect of LAE inactivates the viral particle and can intercept the virus at the end of the cycle when it gains the extracellular environment. Therefore, LAE is a promising source of antiviral agents.

NS2B-NS3 protease inhibitors as promising compounds in the development of antivirals against Zika virus: A systematic review.

Zika virus (ZIKV) infections are associated with severe neurological complications and are a global public health concern. There are no approved vaccines or antiviral drugs to inhibit ZIKV replication. NS2B-NS3 protease (NS2B-NS3 pro), which is essential for viral replication, is a promising molecular target for anti-ZIKV drugs. We conducted a systematic review to identify compounds with promising effects against ZIKV; we discussed their pharmacodynamic and pharmacophoric characteristics. The online search, performed using the PubMed/MEDLINE and SCOPUS databases, yielded 56 articles; seven relevant studies that reported nine promising compounds with inhibitory activity against ZIKV NS2B-NS3 pro were selected. Of these, five (niclosamide, nitazoxanide, bromocriptine, temoporfin, and novobiocin) are currently available on the market and have been tested for off-label use against ZIKV. The 50% inhibitory concentration values of these compounds for the inhibition of NS2B-NS3 pro ranged at 0.38-21.6 µM; most compounds exhibited noncompetitive inhibition (66%). All compounds that could inhibit the NS2B-NS3 pro complex showed potent in vitro anti-ZIKV activity with a 50% effective concentration ranging 0.024-50 µM. The 50% cytotoxic concentration of the compounds assayed using A549, Vero, and WRL-69 cell lines ranged at 0.6-1388.02 µM and the selectivity index was 3.07-1698. This review summarizes the most promising antiviral agents against ZIKV that have inhibitory activity against viral proteases.

Epilepsy in children with Congenital Zika Syndrome: A systematic review and meta-analysis.

OBJECTIVES: To estimate the overall frequency of epilepsy in children with congenital Zika syndrome (CZS) and describe the profile of seizures and the response rate to anti-epileptic treatment in this group of patients. METHODS: A systematic review and meta-analysis were conducted following the Cochrane Handbook and preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. PubMed/MEDLINE, Scopus, Cochrane Library, SciELO, and LILACS were searched until June 23, 2020. Observational studies that evaluated the frequency of epilepsy in children diagnosed with CZS according to international criteria were included in the study. RESULTS: Fourteen studies evaluating 903 patients diagnosed with CZS were pooled in a meta-analysis. All studies were conducted in Brazil, with reports published between 2016 and 2020, and included children diagnosed with CSZ from 0 to 40 months of age. The overall rate of epilepsy in children diagnosed with CZS was estimated at 60% (95% confidence interval [CI] 0.51-0.68). The studies included in this review show that the frequency of epilepsy in patients with CSZ varies with age, with higher rates in older children. Epileptic spasms was the primary type of seizure observed in this group, followed by focal and generalized crisis. The response rate to anti-epileptic drugs was considerably low, ranging from 20% of seizure control in the first year and 30% in the second year. SIGNIFICANCE: Children with CZS presented a high cumulative incidence of epilepsy episodes with increased severity and a low response to anti-epileptic therapy, which is associated with the extensive damage caused by the Zika virus on the cortical structures of patients.

Quercetin as a potential nutraceutic against coronavirus disease 2019 (COVID-19) / La Quercetina como un potencial nutracéutico contra la enfermedad por coronavirus 2019 (COVID-19)

INTRODUCTION: The coronavirus disease 2019 (COVID-19) is a viral disease that affects several human organs and sys¬tems. Preventive or prophylactic treatments are specifically useful in emerging infectious diseases such as COVID-19 because they reduce the need for hospitalization and public health spending. Although the SARS-CoV-2 preventive effect of several therapeutic agents (e.g., hydroxychloroquine/chloroquine, remdesivir, lopinavir, and ritonavir) has been extensively evaluated, none of them have demonstrated significant clinical efficacy. METHOD: We aim to address and discuss the recently published studies on the chemoprophylactic potential of quer¬cetin against SARS-CoV-2. A literature search was carried out on different databases, such as PubMed/MEDLINE, Scielo, Scopus, Web of Science, Cochrane Library, and Clinical Trials.gov. Studies that report the effect of quercetin against SARS-CoV-2 or other types of coronaviruses were included and critically evaluated. RESULTS: Studies have shown that quercetin, an FDA-approved flavonoid used as an antioxidant and anti-inflamma¬tory agent, inhibits the entry of coronavirus (SARS-CoV) into the host cell. Moreover, an in silico study showed that quercetin is a potent inhibitor of the SARS-CoV-2 main protease (Mpro), suggesting that this flavonoid is also active against COVID-19. CONCLUSIONS: Because quercetin might prevent and lessen the duration of SARS-CoV-2 infections, it is plausible to assume that the prophylactic use of this flavonoid produces several clinical benefits. However, this preliminary evidence needs to be confirmed by in vitro assays and, posteriorly, in randomized clinical trials

INTRODUCCIÓN: La enfermedad del coronavirus 2019 (COVID-19) es una enfermedad viral que afecta a varios órganosy sistemas. Los tratamientos preventivos o profilácticos son especialmente útiles en enfermedades infecciosas emergentes como COVID-19 porque reducen la necesidad de hospitalización y el gasto en salud pública. Aunque el efecto preventivo del SARS-CoV-2 de varios agentes terapéuticos (e.g., hidroxicloroquina/cloroquina, remdesivir,lopinavir y ritonavir) se ha evaluado ampliamente, ninguno de ellos ha demostrado una gran eficacia clínica. MÉTODO: Por lo tanto, aquí nuestro objetivo es abordar y discutir los estudios publicados recientemente sobre el potencial quimioprofilático de la quercetina contra el SARS-CoV-2. METODOLOGÍA: Se realizó una búsqueda de la literaturaen bases como PubMed/MEDLINE, Scielo, Scorpus, Web of Science, Cochrane Library y Clinical Trials.gov. Se incluyeron y evaluaron críticamente estudios que abordan la quercetina contra el SARS-CoV-2 u otros tipos decoronavirus. RESULTADOS: Algunos estudios han demostrado que la quercetina, un flavonoide aprobado por la FDA que se utiliza como agente antioxidante y antiinflamatorio, inhibe la entrada del coronavirus (SARS-CoV) en la célula huésped.Además, un estudio in silico mostró que la quercetina es un potente inhibidor de la proteasa principal del SARSCoV-2 (Mpro), lo que sugiere que este flavonoide también es activo contra COVID-19. CONCLUSIONES: Debido a que la quercetina podría prevenir y disminuir la duración de las infecciones por SARSCoV-2, es plausible suponer que el uso profiláctico de este flavonoide produce varios beneficios clínicos. Pero, estas pruebas preliminares deben ser confirmadas mediante ensayos in vitro y, posteriormente, en un ensayo clínico aleatorizado

Pristimerin isolated from Salacia crassifolia (Mart. Ex. Schult.) G. Don. (Celastraceae) roots as a potential antibacterial agent against Staphylococcus aureus.

ETHNOPHARMACOLOGICAL RELEVANCE: Pristimerin is a triterpenoid considered the main component of Salacia crassifolia extracts. This terpene has shown promising antitumor, anti-inflammatory, and antimicrobial effects. Likewise, S. crassifolia has been used in traditional medicine to treat cancer and as an antimicrobial and anti-inflammatory agent. AIM OF THE STUDY: This study aimed to evaluate the antibacterial activity of the hexane extract of Salacia crassifolia roots (HER) and its isolate, pristimerin, against pathogenic bacteria. MATERIALS AND METHODS: First, we evaluated the spectrum of action of HER and pristimerin by the determination of the minimum inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC). Subsequently, we analyzed the time-kill curve of these plant-derived compounds against Staphylococcus aureus. Then, we examined their mode of action by three different assays: the crystal violet methodology, the release of intracellular material, and transmission electron microscopy methods (TEM). Finally, we evaluated the effect of HER and pristimerin on the pre-formed biofilm of S. aureus by the crystal violet assay, the synergistic effect by the checkerboard method, the cytotoxicity against Vero cells, and the in silico activity using the online software PASS. RESULTS: HER and pristimerin presented a narrow spectrum of action against Gram-positive bacteria (MIC 0.195-25 µg/mL), and their primary mode of action is the alteration of membrane permeability of S. aureus. Our results show that the compounds disrupted the pre-formed biofilm of S. aureus in a dose-dependent manner. Furthermore, HER and pristimerin presented a significant synergic effect after the combination with well-known antibiotics, which was associated with the ability of these phytomedicines to change membrane permeability. Regarding the cytotoxic effect, the selective index (SI) of HER ranged from 0.37 to 11.86, and the SI of pristimerin varied from 0.24 to 30.87, according to the bacteria tested. CONCLUSIONS: Overall, HER and pristimerin showed a promising antibacterial effect in vitro through the alteration of membrane permeability of S. aureus.

The potential of drug repositioning as a short-term strategy for the control and treatment of COVID-19 (SARS-CoV-2): a systematic review.

The novel human coronavirus (SARS-CoV-2), the causative agent of COVID-19, has quickly become a threat to the public health and economy worldwide. Despite the severity of some cases, there are no current pathogen-specific antivirals available to treat the disease. Therefore, many studies have focused on the evaluation of the anti-SARS-CoV-2 activity of clinically available drugs. Here, we conducted a systematic review to describe the drug repositioning strategy against SARS-CoV-2 and to discuss the clinical impact of this approach in the current pandemic context. The systematic review was performed on March 23, 2020, using PubMed/MEDLINE, Scopus, Cochrane Library, and Biblioteca Virtual de Saúde (BVS). The data were summarized in tables and critically analyzed. After the database search, 12 relevant studies were identified as eligible for the review. Among the drugs reported in these studies, 57 showed some evidence of antiviral activity. Antivirals, especially antiretrovirals, are the main class of therapeutic agents evaluated against COVID-19. Moreover, studies have reported the anti-SARS-CoV-2 activity of antitumor (16%; 9/57), antimalarial (7%, 4/57), and antibacterial (5%; 3/57) agents. Additionally, seven pharmacological agents (chloroquine, tetrandrine, umifenovir (arbidol), carrimycin, damageprevir, lopinavir/ritonavir) are in phase IV of clinical trials. Due to the evidence of the anti-SARS-CoV-2 activity of various clinically available agents, drug repositioning stands out as a promising strategy for a short-term response in the fight against the novel coronavirus.

Virucidal activity of proanthocyanidin against Mayaro virus.

Mayaro virus (MAYV) is a sublethal arbovirus transmitted by mosquitoes with possible installation of an urban cycle in the Americas. Its infection causes disabling arthralgia, and still, there is no vaccine or treatment to it. We recently investigated nearly 600 compounds by molecular docking and identified epicatechin as a potent antiviral against MAYV. The root extract of Maytenus imbricata showed anti-MAYV activity and two isolated compounds from this plant were also evaluated in vitro. Proanthocyanidin (PAC), a dimer containing epicatechin, showed an effective concentration for 50% of the cells infected by MAYV (EC50) of 37.9 ±â€¯2.4 µM and a selectivity index (SI) above 40. PAC showed significant virucidal activity, inhibiting 100% of the virus proliferation (7 log units), and caused moderate effect during adsorption and virus internalization stage. However, PAC was unable to block the infection when only the cells were pretreated. It was observed a reduction in virus yields when adding PAC at different moments after infection. The set of results indicates that PAC binds to viral and non-cellular elements and may inactivate the MAYV. The inactivation occurs before infection or when the virus reaches the extracellular environment from the 2nd cycle of infection that could block its progression cell-to-cell or to tissues not yet infected.