Publications by authors named "Alessandra Valverde"

Snakebite envenomation is a public health issue that can lead to mortality and physical consequences. It is estimated that 5.4 million venomous snake bites occur annually, with 130,000 deaths and 400,000 amputations.

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Secondary metabolites from land and marine (micro)organisms have been at the focus of the drug discovery process for many years. One of the reasons for this success is nature's incredible ability to create intricate molecular scaffolds. Such structural richness, however, makes the structural elucidation, and the absolute configuration assignment in particular, a challenging process.

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The genus Clusia L. is highly diverse in Central and South America, comprising about 300 species, including trees and shrubs, hemiepiphytes, epiphytes, and lianas. This genus deserves attention due to its wide range of biological activities.

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Heliannuols are a unique class of sesquiterpenes isolated mostly from , commonly known as sunflower. The interesting allelopathic properties, combined with their unprecedented carbon skeletons, have drawn wide attention to phytochemistry and synthetic groups. So far, 14 heliannuols (heliannuols A-N) have been described in the literature, although some of them have not yet been validated by total synthesis.

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Oral squamous cell carcinoma (OSCC) is a worldwide public health problem, with high morbidity and mortality rates. The development of new drugs to treat OSCC is paramount. plant species have shown many biological activities.

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Vibrational circular dichroism (VCD) is one of the most powerful techniques to assess the stereochemistry of chiral molecules in solution state. The need for quantum chemical calculations to interpret experimental data, however, has precluded its widespread use by non-experts. Herein, we propose the search and validation of IR and VCD spectral markers to circumvent the requirement of DFT calculations allowing for absolute configuration assignments even in complex mixtures.

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The combination of computational methods and experimental data from Nuclear Magnetic Resonance (NMR) is a considerably valuable tool in the elucidation of new natural product structures and, also, in the structural revision of previously reported compounds. Until recently, only classical statistical parameters were used, for example, linear correlation coefficient (R ), mean absolute error (MAE), or root mean square deviation (RMSD), as a way to statistically "validate" the structure pointed out by experimental NMR spectra. Regarding the resolution of the relative configuration of organic molecules, novel tools were available in the last few years to assist in the NMR elucidation process.

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Porifera, commonly referred to as marine sponges, are acknowledged as major producers of marine natural products (MNPs). Sponges of the genus have attracted much attention over the years. They are widespread in all continents, and several structurally unique compounds have been identified from this species.

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Access to genetic resources (GR) and/or traditional knowledge associated with genetic resources (ATK) has been regulated in Brazil since 2001. The law 13,123 / 2015 determined a significant change in the theme, mainly on the rules of distribution of benefits obtained for conservation and sustainable use of biodiversity, the access to technology and technology transfer, the exploitation of products or reproductive material from the GR or ATK and consignment to the outside of part or all the living or dead organism shipped for GR. The implementation of international treaties on GR and ATK for research, biotechnological development and bioprospecting have been causing difficulties for Brazilian researchers, mainly due to the lack of information and dissemination available for compliance with the legislation.

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Recently, structural elucidation of natural products has undergone a revolution. The combined use of different modern spectroscopic methods has allowed obtaining a complete structural assignment of natural products using small amounts of sample. However, despite the extraordinary ongoing advances in spectroscopy, the mischaracterization of natural products has been and remains a recurrent problem, especially when the substance presents several stereogenic centers.

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The extensive marine biodiversity has proved to be a promising source of substances with biomedical potential. In this study, the cytotoxicity of the Brazilian octocoral Phyllogorgia dilatata (Gorgoniidae) was evaluated against two tumor cell lines and three bacterial strains. The methanol/dichloromethane crude extract presented no antibacterial activity up to the highest concentration tested (512 µg/mL), however it revealed a noteworthy antiproliferative effect against HCT-116 (80%) and MCF-7 (54%) cell lines at 50 μg/mL.

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Marine sponges from the Plakinidae family are well known for hosting cytotoxic secondary metabolites and the Brazilian Atlantic coast and its oceanic islands have been considered as a hotspot for the discovery of new Plakinidae species. Herein, we report the chemical profile among cytotoxic extracts obtained from four species of Plakinidae, collected in Fernando de Noronha Archipelago (PE, Northeastern Brazil). Crude organic extracts of Plakinastrella microspiculifera, Plakortis angulospiculatus, Plakortis insularis, and Plakortis petrupaulensis showed strong antiproliferative effects against two different cancer cell lines (HCT-116: 86.

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Phorbas is a widely studied genus of marine sponge and produce structurally rich cytotoxic metabolites. Still, only few studies have assessed metabolites present in Brazilian species. To circumvent redundancy, in this work, we applied and herein report the use of a scouting liquid chromatographic system associate to the design of experiment produced by the DryLab® software to obtain a fast and efficient chromatographic separation of the active hexane fraction, further enabling untargeted high-resolution mass spectrometry (HRMS) data.

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Bovine mastitis is an infectious disease that affects the mammary gland of dairy cattle with considerable economic losses. Staphylococcus aureus is the main microorganism involved in this highly contagious process, and the treatment is only using antibiotics. Currently, the search for new treatment and/or compounds is still in need due to microbial resistance.

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In T. cruzi, a causative agent of Chagas disease, phosphoenolpyruvate carboxykinase (TcPEPCK) is associated with carbohydrate catabolism. Due to its importance in the metabolism of the parasite, it has become a promising target for the development of new drugs against Chagas disease.

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Functionalized micro- and nano-sized magnetic beads (MBs) have been widely used as versatile supports for proteins, enzymes, and drugs. Immobilized protein on MB surfaces has been successfully applied for ligand fishing assays allowing for direct identification of active ligands from complex mixtures, such as natural products and synthetic libraries. MBs with different properties such as different core compositions, sizes, coatings, and surface modifications are available commercially.

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Stereochemical determinations based solely on the comparison of optical rotation (OR) measured at a single wavelength may commonly result in misassignments. Herein, we use vibrational and electronic CD, NMR, OR, and DFT calculations, to confirm the absolute configuration (AC) of the cytotoxic marine polyketides spongosoritin A (1) and 9,10-dihydrospongosoritin A (2) as (-)-(6R,8R) and (-)-(6R,8S), respectively. The AC of natural 1 and 2 has so far relied upon comparisons of OR values only.

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Blue and yellow light affected metabolism and the morphology. Blue and red promote the DOXP/MEP pathway. ADS gene expression was increased in plants cultivated under blue, promoting artemisinin content.

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Background: In Brazil, the Bothrops genus accounts for 87% of registered snakebites, which are characterized by hemorrhage, tissue necrosis, hemostatic disturbances, and death. The treatment recommended by governments is the administration of specific antivenoms. Although antivenom efficiently prevents venom-induced lethality, it has limited efficacy in terms of preventing local tissue damage.

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Background: Oral squamous cell carcinoma (OSCC) is one of the ten most common types of cancer worldwide. Plants of the genusPiper are used in traditional medicine to treat cancer, and they have a vast diversity of phytochemicals with cytotoxic potential. Purpose and Study Design: In this work, we analyzed the cytotoxic and selective potential of extracts and semipurified fractions of Piper mollicomum (PM), Piper truncatum (PT), Piper cernuum (PC), Piper arboreum (PA), and Piper cabralanum (PCa) using three different OSCC cell lines (SCC4, SCC9 and SCC25), and we measured their in vivo toxicities and conducted chemical analyses of their active fractions.

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Article Synopsis
  • The Aedes aegypti mosquito is a primary carrier of arboviruses, and current insecticides are not only toxic to mammals and the environment, but they also have limited effectiveness.
  • Natural products from the Piper genus, particularly the n-hexanic extract of Piper solmsianum and its component eupomatenoid-6, show potential as alternatives for larvicidal treatments.
  • The study found that the extract was highly effective in killing mosquito larvae and identified eupomatenoid-6 as a promising insecticide with low toxicity to human cells.
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This study aims the anatomical description and chemical characterization of aerial parts of Clusia criuva Cambess., Clusiaceae in addition to the evaluation of the antioxidant activity of crude extracts, correlated to the flavonoid content. The morphological characterization was performed using traditional techniques of plant anatomy.

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Background: The genus Piper L. has the shikimic acid pathway predominantly expressed, biosynthesizing many cinnamic acid derivatives (CAD).

Objective: Neolignans comprise an important class of CAD that exhibit a wide range of pharmacological properties such as antibacterial, antitumor, insecticidal, anti-inflammatory, antioxidant, smooth muscle relaxant, neuroprotective, antiprotozoal and against platelet aggregation factor.

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Article Synopsis
  • Approximately 3.3 billion people are at risk of malaria, leading to nearly 700,000 deaths annually, highlighting the need for new anti-malarial drugs.
  • Researchers developed new 2-(trifluoromethyl)[1,2,4]triazolo[1,5-a]pyrimidine derivatives to improve drug efficacy against malaria by modifying existing compounds like mefloquine and amodiaquine.
  • The study found that these new compounds significantly enhanced activity against the malaria-causing parasite P. falciparum, with some derivatives showing very low IC₅₀ values and high selectivity, indicating promising potential in malaria treatment.
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