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Objective: To describe the origin, transmission, morphological and genetic characteristics of SARS-CoV-2 and its pathogenicity mechanisms. Bibliographic review: At the end of December 2019, health centers in Wuhan, Hubei-China province, observed several cases of pneumonia of unknown origin, associated with a new etiologic agent, a virus, with a similar, but distinct, genomic sequence of SARS-CoV and MERS-CoV, named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The most common symptoms at the beginning of the infection are fever, cough, fatigue, olfactory and taste disorders; on the other hand, severe cases include pulmonary impairment and hypoxia. Currently, there are no antiviral agents with proven clinical efficacy and vaccination occurs in slow steps in most countries, with symptomatic treatment and life support still being the main therapeutic interventions available. Final considerations: SARS-CoV-2 presents itself as one of the biggest public health problems in the world nowadays. The search for new drugs to treat COVID-19 is constant, however, so far no new drug is available for use with 100% proven clinical efficacy.

Context: Buchenavia tetraphylla (Aubl.) RA Howard (Combretaceae: Combretoideae) is an ethnomedicinal plant with reported antifungal action. Objective: This study evaluates the antimicrobial activity of B. tetraphylla leaf extracts against clinical isolates of Candida albicans. The morphological alterations, combinatory effects with fluconazole and the cytotoxicity of the active extract were analyzed. Materials and methods: Extracts were obtained using different solvents (hexane: BTHE; chloroform: BTCE; ethyl acetate: BTEE; and methanol: BTME). Antimicrobial activity was determined by the broth microdilution method using nine strains of C. albicans isolated from vaginal secretions and one standard strain (UFPEDA 1007). Results: All extracts showed anti-C. albicans activity, including against the azole-resistant strains. The MIC values ranged from 156 to 2500 μg/mL for the BTHE; 156 to 1250 μg/mL for the BTCE; 625 to 1250 μg/mL for the BTME and 625 μg/mL to 2500 μg/mL for the BTEE. BTME showed the best anti-C. albicans activity. This extract demonstrated additive/synergistic interactions with fluconazole. Scanning electron microscopy analysis suggested that the BTME interferes with the cell division and development of C. albicans. BTME showed IC50 values of 981 and 3935 μg/mL, against J774 macrophages and human erythrocytes, respectively. This extract also enhanced the production of nitric oxide by J774 macrophages. Discussion and conclusion: Buchenavia tetraphylla methanolic extract (BTME) is a great source of antimicrobial compounds that are able to enhance the action of fluconazole against different C. albicans strains; this action seems related to inhibition of cell division.

Objective: To review the antidepressant activity and mechanisms of action of plants that have antidepressant action. Literature Review: The use of plants for medicinal purposes has been used as an adjunct to the treatment of depression due to easy access by the population, few side effects and lower cost. Based on the studies, the plants St. John's wort, ground turmeric, anona and lavender have antidepressant potential for acting in different ways in depression, either by inhibiting the reuptake of serotonin or by modulation in the dopaminergic and serotonergic pathways. Final Considerations: From the studies of the mechanisms of action it was found that the plants studied can modulate the brain signaling pathways responsible for the patient's mood, with the reuptake of serotonin (inhibition of the serotonin transporter protein) the main mechanism of action shared between them. In addition, some of these plants can modulate not only the concentrations of serotonin in the synaptic cleft, but also dopamine. It is worth mentioning that, although these actions have been scientifically proven, much research is still needed to ensure the safe use of these agents as herbal medicines in the alternative or adjunctive treatment of depressive disorders.

Objective: To describe the importance of medicinal plants in the social and pharmacological context, demonstrating the anti-inflammatory therapeutic potential and the mechanism of action of drugs present in the chemical composition of four plants present in the Brazilian flora. Methods: A bibliographic survey on the topic was carried out, using the descriptors: Activity, Anti-inflammatory, Plants, Flora, Brazilian. In Scielo, Google Scholar and PUBMED databases. For the inclusion of works, the following criteria were used: Articles from research relevant to the topic (regardless of date) and relevant publications from the year 2007. Results: The inflammatory process is a target for the treatment of various diseases and development new treatments are needed. We discuss here the anti-inflammatory potential and the mechanism of action of the following plants: Uncaria tomentosa, Schinus terebinthifolius Raddi and Mentha piperita demonstrated through in vitro studies and murine models of diseases. The species showed anti-inflammatory action by reducing the production of inflammatory mediators and inhibiting the activity of important pro-inflammatory enzymes, such as phospholipase A2 and cycloxygenase. Final considerations: The four plant species covered in this article had significant anti-inflammatory effects, therefore, they can be suggested as a source of potential new drugs.

Several plant-derived compounds have been screened by antioxidant assays, but many of these results are questionable, since they do not evaluate the pharmacologic parameters. In fact, the development of better antioxidants stills a great challenge. In vitro cell-based assays have been employed to assess the antioxidant effect of various compounds at subcellular level. Cell-based assays can also reveal compounds able to enhance the antioxidant pathways, but without direct radical scavenging action (which could not be detected by traditional assays). These methodologies are general of easy implementation and reproducible making them suitable for the early stages of drug discovery. Hydrogen peroxide, a nonradical derivative of oxygen, can be employed as an oxidative agent in these assays due its biochemical properties (presence of all biological systems, solubility) and capacity to induce cell death. Truthfully, if their limitations are understood (such as difference on cell metabolism when in in vitro conditions), these cell-based assays can provide useful information about the pathways involved in the protective effects of phytochemicals against cell death induced by oxidative stress, which can be exploited to develop new therapeutic approaches.

Objective: To describe the role of oxidative/nitrosative stresses in the pathogenesis of placental malaria and complications for the fetus. Bibliographic review: Placental malaria results from the sequestration of erythrocytes infected by Plasmodium falciparum in the blood microcirculation of the placental interventional spaces, leading to the infiltration of activated leukocytes in these sites, with subsequent production of cytokines and chemokines. These mediators, associated with phagocytosis of parasites and infected cells, activate the oxidative/nitrosative stresses pathways, producing free radicals and oxidation/nitration molecules, which act by attacking compounds of the cell structure of both the parasite and the host cells, causing damage to the integrity of the placental barrier and leading to insufficiency of the placenta to support fetal development. Final considerations: Therefore, we conclude that the immune response and oxidative/nitrosative stresses play an important role not only in the defense of the patient (reducing parasitaemia), but also in the progression of the disease and placental invasion, leading to serious changes and complications to the fetus.

Objective: To describe the anxiolytic activity and possible mechanisms of action on the central nervous system of plants found in the region known as legal Amazon in the Brazilian territory. Bibliographic Review: For this, five plants popularly used as tranquilizers and to treat insomnia in the forms of teas and extracts were selected, they are: passion fruit, valerian, chamomile, lemon grass and bay leaf. A bibliographic survey of articles, mainly original research, reporting comparative studies of the anxiolytic effects of each plant against control groups, as well as its possible mechanisms of action on the nervous system through preclinical and clinical studies, was performed. Conclusion: All the selected plants exhibited comparable and even superior anxiolytic effects when compared to classes of drugs such as benzodiazepines, with minimization or elimination of side/adverse effects. In addition, all reviewed studies indicated some involvement of gamma-aminobutyric acid (GABA) receptors activation by plant chemical constituents in anxiolytic action. Due to the minimization of adverse effects and the absence of dependence, herbal medicine appears as an important alternative therapy to treat anxiety disorders.

Severe wounds result in large lesions and/or loss of function of the affected areas. The treatment of wounds has challenged health professionals due to its complexity, especially in patients with chronic diseases (such as diabetes), and the presence of pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa. Taking this into consideration, the development of new therapies for wound healing requires immediate attention. Ethnopharmacological studies performed in different countries have shown the use of several plants from the Asteraceae family as wound-healing agents. Evidences gained from the traditional medicine have opened new ways for the development of novel and more efficient therapies based on the pharmacological properties of these plants. In this article, we discuss the literature data on the use of Asteraceae plants for the treatment of wounds, based on the ethnopharmacological relevance of each plant. Special attention was given to studies showing the mechanisms of action of Asteraceae-derived compounds and clinical trials. Ageratina pichinchensis (Kunth) R.M. King and H. Rob. and Calendula officinalis L. preparations/compounds were found to show good efficacy when assessed in clinical trials of complicated wounds, including venous leg ulcers and foot ulcers of diabetic patients. The compounds silibinin [from Silybum marianum (L.) Gaertn.] and jaceosidin (from Artemisia princeps Pamp.) were identified as promising compounds for the treatment of wounds. Overall, we suggest that Asteraceae plants represent important sources of compounds that may act as new and efficient healing products.

Plant-derived products have played a fundamental role in the development of new therapeutic agents. This study aimed to analyze antimicrobial, antibiofilm, cytotoxicity and antiproliferative potentials of the extract and fractions from leaves of Himatanthus drasticus, a plant from the Apocynaceae family. After harvesting, H. drasticus leaves were macerated and a hydroalcoholic extract (HDHE) and fractions were prepared. Antimicrobial tests, such as agar-diffusion, Minimum Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) were carried out against several bacterial species. Staphylococcus aureus, Pseudomonas aeruginosa, Listeria monocytogenes and Klebsiella pneumoniae were inhibited by at least one extract or fraction in the agar-diffusion assay (inhibition halos from 12 mm to 30 mm). However, the lowest MIC value was found for HDHE against K. pneumoniae. In addition, HDHE and its fractions were able to inhibit biofilm formation at sub-inhibitory concentrations (780 µg/mL and 1.56 µg/mL). As the best activities were found for HDHE, we selected it for further assays. HDHE was able to increase ciprofloxacin (CIP) activity against K. pneumoniae, displaying synergistic (initial concentration CIP + HDHE: 2 µg/mL + 600 µg/mL and 2.5 µg/mL + 500 µg/mL) and additive effects (CIP + HDHE: 3 µg/mL + 400 µg/mL). This action seems to be associated with the alteration in bacterial membrane permeability induced by HDHE (as seen by propidium iodide labeling). This extract was non-toxic for red blood cell or human peripheral blood mononuclear cells (PBMCs). Additionally, it inhibited the lipopolysaccharide-induced proliferation of PBMCs. The following compounds were detected in HDHE using HPLC-ESI-MS analysis: plumieride, plumericin or isoplumericin, rutin, quercetin and derivatives, and chlorogenic acid. Based on these results we suggest that compounds from H. drasticus have antimicrobial and antibiofilm activities against K. pneumoniae and display low cytotoxicity and anti-proliferative action in PBMC stimulated with lipopolysaccharide.