Publications by authors named "Gustavo Echeverria"

(Z)-3-butylamino-4,4,4-trifluoro-1-(2-hydroxyphenyl)but-2-en-1-one (1), a new β-aminoenone, has been investigated in terms of its intra- and intermolecular interactions. Vibrational, electronic and NMR spectroscopies were used for the characterization, while X-ray diffraction methods afforded the determination of the crystal structure. The compound is arranged in the crystal lattice as centre-symmetric H-bonded dimeric aggregates (C2/c monoclinic space group).

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Q fever, caused by the bacterium , is a zoonotic disease that has been largely overlooked despite presenting significant risks to both animal and public health. Although well studied in some countries, in most countries in Latin America, there's a lack of information on infection, its prevalence, and its impact on both livestock and human populations. To address this gap, we conducted a serosurvey among farm workers, cattle, sheep, and dogs on two dairy farms in Ecuador using a commercial ELISA kit.

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The 1-acyl thiourea family [RC(O)NHC(S)NRR] exhibits the flexibility to incorporate a wide variety of substituents into their structure. The structural attributes of these compounds are intricately tied to the type and extent of substitution. In the case of 3-mono-substituted thioureas (R=H), the conformational behavior is predominantly shaped by the presence of an intramolecular N-H ⋅ ⋅ ⋅ O=C hydrogen bond.

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Osteosarcoma cancers are becoming more common in children and young adults, and existing treatments have low efficacy and a very high mortality rate, making it pressing to search for new chemotherapies with high efficacy and high selectivity index. Copper complexes have shown promise in the treatment of osteosarcoma. Here, we report the synthesis, characterization, and anticancer activity of [Cu(N-N-Fur)(NO)(HO)] complex where N-N-Fur is (E)-'-(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazide.

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Although several brands of tuberculin purified protein derivatives (PPDs) are available for diagnosing bovine tuberculosis (bTB), comparative studies to determine their diagnostic accuracy are infrequent. In Ecuador we compared two different PPD brands for bTB diagnosis using skin testing and measuring skin thickness increase. Additionally, we evaluated four PPD brands, including those used for skin testing, in the Bovine Tuberculosis Interferon Gamma Test (IFN-γ test) measuring IFN-γ induction in whole blood.

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Article Synopsis
  • Monomeric cobalt complexes [Co(SDZ)phen] and [Co(SDZ)(bq)Cl] were synthesized, with SDZ acting as a bidentate ligand in both.
  • X-ray diffraction studies revealed different coordination environments: complex 1 has a CoN coordination sphere, while complex 2 has a CoNCl core with contributions from another ligand.
  • Both complexes exhibit slow magnetic relaxation under a dc field at low temperatures, with compound 2 showing long-range magnetic ordering due to spin-canted antiferromagnetism, supported by various magnetic measurements.
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Eight Schiff bases, synthesized by the reaction of 4-aminoantipyrine with different cinnamaldehydes, were studied in the solid state by using vibrational spectroscopy (IR) and X-ray diffraction techniques. The analysis was extended to the solution phase through ultraviolet-vis, fluorescence spectroscopy, and cyclic voltammetry. Finally, the crystal structures of four compounds (, , , and ) were determined and studied.

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A multiplex PCR system (m-PCR) has been developed to accurately differentiate the five most important pathogenic species, including the three species associated with infection in dairy cattle (, , and ) and the two species associated with human infections ( and ). The method is low-cost since it employs a simple "heat-shock" method in a TE buffer for DNA extraction. Furthermore, it requires only primers, a Taq polymerase, an agarose gel, and a molecular weight marker for identification.

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Favipiravir is an important selective antiviral against RNA-based viruses, and currently, it is being repurposed as a potential drug for the treatment of COVID-19. This type of chemical system presents different carboxamide-rotameric and hydroxyl-tautomeric states, which could be essential for interpreting its selective antiviral activity. Herein, the tautomeric 3-hydroxypyrazine/3-pyrazinone pair of favipiravir and its 6-substituted analogues, 6-Cl, 6-Br, 6-I, and 6-H, were fully investigated in solution and in the solid state through ultraviolet-visible, H nuclear magnetic resonance, infrared spectroscopy, and X-ray diffraction techniques.

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Nontuberculous mycobacteria (NTM) lung infections are often misdiagnosed as tuberculosis, which can lead to ineffective antibiotic treatments. In this report, we present three cases of NTM lung infections in Ecuador that were initially diagnosed and treated as tuberculosis based on the results of sputum smear microscopy. The patients, all male, included two immunocompetent individuals and one HIV-positive subject.

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Chagas' disease (American Trypanosomiasis) is an ancient and endemic illness in Latin America caused by the protozoan parasite Although there is an urgent need for more efficient and less toxic chemotherapeutics, no new drugs to treat this disease have entered the clinic in the last decades. Searching for metal-based prospective antichagasic drugs, in this work, multifunctional Re(I) tricarbonyl compounds bearing two different bioactive ligands were designed: a polypyridyl NN derivative of 1,10-phenanthroline and a monodentate azole (Clotrimazole CTZ or Ketoconazol KTZ). Five -[Re(CO)(NN)(CTZ)](PF) compounds and a -[Re(CO)(NN)(KTZ)](PF) were synthesized and fully characterized.

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The genus , a unicellular, non-photosynthetic, yeast-like microalgae, is a pathogen of concern for the dairy industry. It causes bovine mastitis that currently cannot be cured, and hence generates significant economic losses in milk production. In this study, for the first time in Ecuador, we identify as the etiologic agent of chronic mastitis in dairy cattle.

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Non-tuberculous mycobacteria that cannot be identified at the species level represent a challenge for clinical laboratories, as proper species assignment is key to implementing successful treatments or epidemiological studies. We re-identified forty-eight isolates of Ziehl-Neelsen (ZN)-staining-positive "acid-fast bacilli" (AFB), which were isolated in a clinical laboratory and previously identified as species but were unidentifiable at the species level with the hsp65 PCR restriction fragment length polymorphism analysis (PRA). As most isolates also could not be identified confidently via , , or DNA sequencing and a nBLAST search analysis, we employed a phylogenetic method for their identification using the sequences of the rDNA, which resulted in the identification of most AFB and a species diversity not found before in our laboratory.

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The crystal structures of bis[1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-ium-4-yl)-1,4-dihydroquinoline-3-carboxylato]copper(II) sulfate heptahydrate, [Cu(CHFNO)]SO·7HO or [Cu(nor)]SO·7HO (nor is norfloxacin), and bis{1-[2-(ethylsulfonyl)ethyl]-2-methyl-5-nitroimide}dinitratocopper(II), [Cu(NO)(CHNOS)] or [Cu(NO)(tnz)] (tnz is tinidazole), were solved by X-ray diffraction. Both complexes crystallize in the space group P2/c, with Z = 4 (for nor) and Z = 2 (for ntz) molecules per unit cell. In [Cu(nor)]SO·7HO, the Cu ion is at the centre of a square-planar environment, trans coordinated to two independent norfloxacin molecules in the zwitterionic form acting as bidentate ligands through one of the carboxyl (cbx) and the carbonyl (cb) O atoms.

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A series of 2-(haloalkyl)-3-azidomethyl and 6-azido chromones has been synthetized, characterized and studied by theoretical (DFT calculations) and spectroscopic methods (UV-Vis, NMR). The crystal structure of 3-azidomethyl-2-difluoromethyl chromone, determined by X-ray diffraction methods, shows a planar framework due to extended π-bond delocalization. Its molecular packing is stabilized by F···H, N···H and O···H hydrogen bonds, π···π stacking and C-O···π intermolecular interactions.

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Two new transition metal complexes with 1-methylimidazole (1-MeIm) and azide as ligands, namely, [Co(1-MeIm)(N)] (1) and [Ni(1-MeIm)(N)] (2), have been synthesized and characterized by IR, Raman, UV-Vis and XPS spectroscopy. Their crystal structures were solved by single-crystal X-ray diffraction. The supramolecular self-assembly of the two complexes is governed by non-classical C-H⋯N hydrogen bonds and C-Hπ interactions.

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Diverse models of intramolecular charge transfer (ICT) have been proposed for interpreting the origin of the charge-transfer (CT) state in donor-acceptor (D-A) dyes. However, a large variety of fused-heterocyclic dyes containing a pseudo-aromatic ring in the rigid structure have shown to be incompatible with them. To approximate a solution within the ICT concept, we reported a novel ICT model called partially aromatized intramolecular charge transfer (PAICT).

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Article Synopsis
  • The study investigates a copper(ii)-hydrazone complex (CuHL) for its synthesis, crystal structure, and anticancer activity against human breast cancer cells in both 2D and 3D models.
  • CuHL has been shown to have greater antitumor activity compared to cisplatin, exhibiting IC50 values of approximately 1.7 μM for MCF7 and 1.6 μM for MDA-MB-231 cells, and significantly reducing mammosphere formation.
  • The complex interacts with DNA, generates reactive oxygen species (ROS), induces programmed cell death, and lowers the levels of breast cancer stem cells, indicating its potential as an effective anticancer agent.
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Background: Studies of T-cell immune responses against SARS-CoV-2 are important in understanding the immune status of individuals or populations. Here, we use a simple, cheap, and rapid whole blood stimulation assay - an Interferon-Gamma Release Assay (IGRA) - to study T-cell immunity to SARS-CoV-2 in convalescent COVID-19 patients and in unexposed healthy contacts from Quito, Ecuador.

Methods: Interferon-gamma (INF-γ) production was measured in the heparinized blood of convalescent and unexposed subjects after stimulation for 24 h with the SARS-CoV-2 Spike S1 protein, the Receptor Binding Domain (RBD) protein or the Nucleocapsid (NP) protein, respectively.

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The compound 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-9-ol (9-hydroxyeucaliptol) has been prepared and characterized by single-crystal X-ray diffraction analysis, infrared, Raman, and UV-visible spectroscopies.

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Three cases of severe odontogenic infections due to nontuberculous mycobacteria (NTM) in Venezuela that were directly associated with dental procedures and the finding of dental unit waterlines (DUWLs) in dental offices that were colonized with mycobacteria species was the reason for assessing the water quality of DUWLs in dental offices in two capital cities in South America, namely, Quito and Caracas. The main water supplies and the water from 143 DUWLs in both cities were sampled and especially checked for contamination with NTM. To measure the overall bacteriological quality of the water also the presence of heterotrophic bacteria, coliform bacteria, and was determined.

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The reaction of -phenyl-1-(pyridin-2-yl)methanimine with copper chloride dihydrate produced the title neutral complex, [CuCl(CHN)(HO)]·HO. The Cu ion is five-coordinated in a distorted square-pyramidal geometry, in which the two N atoms of the bidentate Schiff base, as well as one chloro and a water mol-ecule, form the irregular base of the pyramidal structure. Meanwhile, the apical chloride ligand inter-acts through a strong hydrogen bond with a water mol-ecule of crystallization.

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We report the synthesis and biological evaluation of a ternary copper complex, [Cu(5HTP)(phen)(HO)](NO).2HO, with the antioxidant agent 5-hydroxytryptophan (5-HTP) and phenanthroline (phen, added to improve its lipophilicity and membrane transport). The crystal structure of the complex was determined by X-ray diffraction methods.

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Background: Magnesium is an essential element related with biochemistry of the brain and different types of depression have been associated with its deficiency.

Methods: The structure of a novel magnesium bis(DL-pyroglutamate) (Mg(DL-pGlu)) was elucidated by X-ray crystallography. Wistar rats were used in the in vivo experiments.

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