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.

Inhibition of gelatinase activity of MMP-2 and MMP-9 by extracts of Bauhinia ungulata L / Inibição da atividade gelatinolítica de MMP-2 e MMP-9 a partir de extratos de Bauhinia ungulata l

Metastasis is responsible for the majority of cancer-related deaths. Tumour invasion and metastasis result from processes that include the proteolytic degradation of the extracellular matrix adjacent to the tumour. The matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9, have prognostic influence in human cancers after they cleave the main structural components of the basal membrane. These actions make MMPs an attractive target for cancer and metastasis studies. This study evaluated the inhibitory potency of extracts of Bauhinia ungulata L. (BU) on the gelatinolytic activity of MMP-2 and -9 and recognized the group of secondary compounds responsible for this property. The zymographic analysis of the BU stem revealed that the ethyl acetate partition (D) caused a higher inhibition of MMP-2 and MMP-9. The phytochemical study of D showed the presence of steroids, tannins, and coumarins and the significant presence of alkaloids and flavonoids. The phytochemical study of the fractions obtained through the column chromatography of partition D revealed a significant presence of flavonoids and alkaloids in the fractions that showed better inhibition of the gelatinolytic activity of MMPs. In conclusion, these results suggest that the stem fraction of BU has the potential to inhibit MMP-2 and MMP-9 and should be used in studies on the recognition of active biomolecules.

A metástase é a responsável pela maioria das mortes relacionadas ao câncer. Tanto a invasão tumoral quanto a metástase resultam de processos que incluem a degradação proteolítica da matriz extracelular adjacente ao tumor. As metaloproteinases de matriz (MMPs), especialmente as MMP-2 e MMP-9, têm influência direta no prognóstico dos diversos tipos de câncer humano, pois clivam os principais componentes estruturais da membrana basal. Estas ações fazem das MMPs alvos atraentes para estudos envolvendo câncer e metástase. Este trabalho teve como objetivo avaliar o potencial inibidor dos extratos de Bauhinia ungulata L. (BU) sobre a atividade gelatinolítica das MMP-2 e 9 e reconhecer o grupo de compostos secundários responsáveis por esta propriedade. Análises por zimograma do ramo de BU revelaram que a partição de acetato de etila (D) causou maior inibição de MMP-2 e MMP-9. O estudo fitoquímico de D mostrou a presença de esteróides, taninos e cumarinas e a presença significativa de alcaloides e flavonoides. As frações da coluna cromatográfica da partição D e seus estudos fitoquímicos revelaram uma grande presença de flavonoides e alcaloides nas frações que apresentaram maior inibição da atividade gelatinolítica de MMPs. Em conclusão, estes resultados sugerem que frações do ramo de BU têm o potencial inibidor de MMP-2 e MMP-9 e devem ser utilizadas em estudos envolvendo o reconhecimento de biomoléculas ativas.