Nunes Damiana Antônia de Fátima, Lopes Gabriela Francine Martins, Nizer Waleska Stephanie da Cruz, Aguilar Mariana G de, Santos Felipe Rocha da Silva, Sousa Grasiely Faria de, Ferraz Ariane Coelho, Duarte Lucienir Pains, Brandão Geraldo Célio, Vieira-Filho Sidney Augusto, Magalhães Cintia Lopes de Brito, Ferreira Jaqueline Maria Siqueira, de Magalhães José Carlos
Laboratory of Medical Microbiology, Universidade Federal de São João del-Rei, Divinópolis, MG, Brazil.
Department of Health Sciences, Carleton University, Ottawa, ON, Canada.
J Ethnopharmacol. 2023 Jul 15;311:116436. doi: 10.1016/j.jep.2023.116436. Epub 2023 Mar 30.
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.
This study aimed to demonstrate the effects of ethyl acetate extracts of leaves (LAE) and branches (TAE) of Maytenus quadrangulata against MAYV.
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 (EC).
The leaves (LAE; EC 12.0 μg/mL) and branches (TAE; EC 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.
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.
马亚罗病毒（MAYV）是一种流行于亚马逊地区的虫媒病毒，该地区包括巴西北部和中西部地区的各州，涵盖了世界上最大的热带森林——亚马逊森林。埃及伊蚊可能传播该病毒这一情况得到证实，且巴西近期出现了病例，主要集中在北部地区的大型中心城市，这使得马亚罗热被列为一种新兴疾病。传统医学常用于治疗各种疾病，主要是当地河边居民使用。形态相似的美登木属的一些物种通常被用于治疗感染和炎症。在此背景下，我们的研究小组研究并证实了几种植物源化合物的抗病毒活性。然而，该属的几个物种尚未得到研究，因此值得关注。
本研究旨在证明四角美登木叶（LAE）和枝（TAE）的乙酸乙酯提取物对MAYV的作用。
使用哺乳动物细胞（Vero细胞）评估提取物的细胞毒性。在MAYV感染细胞并用提取物处理后，我们评估了选择性指数（SI）、杀病毒作用、病毒吸附和内化以及对病毒基因表达的影响。通过使用RT-qPCR定量病毒基因组并分析对感染细胞中病毒产量的影响来确认抗病毒作用。治疗是基于对50%感染细胞具有保护作用的有效浓度（EC）进行的。
叶（LAE；EC 12.0μg/mL）和枝（TAE；EC 101.0μg/mL）提取物对病毒表现出显著的选择性，SI值分别为79.21和9.91，被认为是安全的。植物化学分析表明，抗病毒作用与儿茶素的存在有关，主要存在于LAE中。由于该提取物即使在高病毒载量[感染复数（MOI）为1和5]下也能降低病毒细胞病变效应和病毒产生，因此被选用于后续研究。LAE的作用导致病毒基因表达显著降低。当在感染前或复制阶段将LAE添加到病毒中时，病毒滴度大幅降低，与感染且未处理的细胞相比，病毒产生减少多达5个对数单位。
通过动力学复制，在整个病毒周期中，用LAE处理的Vero细胞中未检测到MAYV。LAE的杀病毒作用使病毒颗粒失活，并能在病毒获得细胞外环境的周期结束时拦截病毒。因此，LAE是一种有前景的抗病毒药物来源。
