ABSTRACT
During the growing season of 2021, 201 soil samples from conventionally and organically managed fields from 10 European countries and 8 cropping systems were taken, and 192 residues of synthetic pesticides were analyzed. Pesticide residues were found in 97% of the samples, and 88% of the samples contained mixtures of at least 2 substances. A maximum of 21 substances were found in conventionally managed fields, and a maximum of 12 were found in organically managed fields. The number and concentration of pesticide residues varied significantly between conventional and organic fields in 70 and 50% of the case study sites, respectively. Application records were available for a selected number of fields (n = 82), and these records were compared to the detected substances. Residues from 52% of the applied pesticides were detected in the soils. Only 21% of the pesticide residues detected in the soil samples were applied during the 2021 growing season. From the application data, predicted environmental concentrations of residues in soil were calculated and compared to the measured concentrations. These estimates turned out not to be accurate. The results of this study show that most European agricultural soils contain mixtures of pesticide residues and that current calculation methods may not reliably estimate their presence.
Subject(s)
Pesticide Residues , Pesticides , Soil Pollutants , Pesticide Residues/analysis , Pesticide Residues/chemistry , Soil/chemistry , Agriculture , Pesticides/analysis , EuropeABSTRACT
Chemical processes taking place on ice-grain mantles are pivotal to the complex chemistry of interstellar environments. In this study, we conducted a comprehensive analysis of the catalytic effects of an amorphous solid water (ASW) surface on the reaction between ammonia (NH3) and formaldehyde (H2CO) to form aminomethanol (NH2CH2OH) using density functional theory. We identified potential catalytic sites based on the binding energy distribution of NH3 and H2CO reactants, on a set-of-clusters surface model composed of 22 water molecules and found a total of 14 reaction paths. Our results indicate that the catalytic sites can be categorized into four groups, depending on the interactions of the carbonyl oxygen and the amino group with the ice surface in the reactant complex. A detailed analysis of the reaction mechanism using Intrinsic Reaction Coordinate and reaction force analysis, revealed three distinct chemical events for this reaction: formation of the C-N bond, breaking of the N-H bond, and formation of the O-H hydroxyl bond. Depending on the type of catalytic site, these events can occur within a single, concerted, albeit asynchronous, step, or can be isolated in a step-wise mechanism, with the lowest overall transition state energy observed at 1.3 kcal mol-1. A key requirement for the low-energy mechanism is the presence of a pair of dangling OH bonds on the surface, found at 5% of the potential catalytic sites on an ASW porous surface.
ABSTRACT
The presence of pesticide residues in waterbed sediments poses a significant concern for aquatic ecosystems' health. This study examined pesticide contamination in sediments of 38 water bodies, embedded in agricultural-dominated regions, across eight European countries. Three indicators were targeted: occurrence, type, and concentrations of multiple pesticide residues in sediments. 196 pesticide residues (including degradation products) were tested in the sediment samples. The analytical results showed that only one sample was 'pesticide-free', three samples contained a single pesticide residue, and the remaining 34 samples contained mixtures of residues. Overall, 99 different residues were found in the sediments, with a maximum of 48 in a single sample. Twenty-seven out of the 99 detected residues were not approved for agricultural use at the time of sampling. The numbers of detected residues and pesticide levels varied among countries. AMPA, glyphosate and DDTs were the most common residues in sediment samples with frequencies of 76, 61, and 52%, respectively. The sediments from the Czech Republic had the highest pesticide concentrations, with total pesticide concentrations ranging between 600 and 1200 µg kg-1. The lowest total pesticide concentrations were found in Slovenia, Switzerland, Croatia, and Denmark, ranging between 80 and 120 µg kg-1. Sediments presented a mix of non-persistent and persistent compounds. Twelve of the detected pesticides are very persistent/stable in sediments, raising concerns about the long-term impacts of pesticides. Our study on the distribution of pesticide residues in European sediments provides valuable insights into the extent of pesticide contamination and possible risks of pesticides to water bodies' health. It also underlines the need for monitoring, research, and policy efforts to mitigate the impacts of pesticides, and to evaluate potential risks of re-use of dredged sediments.
ABSTRACT
The present study characterized the filamentous and yeast-like fungal microbiota of the nasal cavity and rectum of Amazonian manatees (Trichechus inunguis) undergoing rehabilitation at the Laboratory of Aquatic Mammals, National Institute of Amazonian Research, Manaus, Amazonas, and determined the antifungal susceptibility of these organisms. Nasal and rectal swabs were collected from 22 calves and three juveniles. The samples were seeded in Sabouraud agar supplemented with chloramphenicol 10%, incubated at 26°C, and observed daily for up to 7 d. The growth of different filamentous and yeast-like fungi was observed among the two anatomical sites. Filamentous fungi were categorized by macro- and microscopic characteristics of the colonies. Representatives of each group were selected for molecular identification based on the internal transcribed spacer region. Yeast identification was performed using MALDI-TOF MS and molecular analyses. Thirteen genera of filamentous fungi and six genera of yeasts were isolated and identified. The dominant filamentous species were Fusarium spp., Aspergillus spp., and Cochliobolus lunatus in the nostril samples and Aspergillus melleus in the rectal samples. Candida was the dominant genus among the identified yeasts at both anatomical sites. In the antifungal susceptibility test, 28 isolates showed resistance to fluconazole (78%), itraconazole (39%), and nystatin (42%). The knowledge of fungal microbiota composition of Amazonian manatees provides information that assists in monitoring the health status of individuals maintained in captivity, as these organisms can behave either as opportunists or as primary pathogens. Moreover, the composition and resistance of these organisms may vary among different rehabilitation institutions or different time frames of search, reinforcing the importance of constant in loco surveillance of these microorganisms. This study provides new perspectives on the fungal diversity in the microbiota of manatees and supports future studies concerning the clinical and epidemiological aspects and the impacts of these agents on the health of Amazonian manatees undergoing rehabilitation.
Subject(s)
Mycobiome , Trichechus inunguis , Animals , Cattle , Antifungal Agents/pharmacology , Brazil/epidemiology , Rectum , Nasal Cavity , Saccharomyces cerevisiae , Trichechus , FungiABSTRACT
Freshwater cetaceans play a significant role as sentinel animals, providing important data on animal species and aquatic ecosystem health. They also may serve as potential reservoirs of emerging pathogens and host virulence genes in their microbiota. In this study, we evaluated virulence factors produced by Gram-negative bacteria recovered from individuals belonging to two populations of free-ranging Amazon river dolphins (Inia geoffrensis). A total of 132 isolates recovered from the oral cavity, blowhole, genital opening and rectum of 21 river dolphins, 13 from Negro River and 8 from Tapajós River, Brazil, were evaluated for the production of virulence factors, such as biofilms and exoproducts (proteases, hemolysins and siderophores), in planktonic and biofilm forms. In planktonic form, 81.1% (107/132) of the tested bacteria of free-ranging Amazon river dolphins were able to produce virulence factors, with 44/132 (33.4%), 65/132 (49,2%) and 54/132 (40,9%) positive for protease, hemolysin and siderophore production, respectively. Overall, 57/132 (43.2%) of the isolates produced biofilms and, under this form of growth, 66/132 (50%), 88/132 (66.7%) and 80/132 (60.6%) of the isolates were positive for protease, hemolysin and siderophore production. In general, the isolates showed a higher release of exoproducts in biofilm than in planktonic form (P < 0.001). The present findings show that Amazon river dolphins harbor potentially pathogenic bacteria in their microbiota, highlighting the importance of monitoring the micro-organisms from wild animals, as they may emerge as pathogens for humans and other animals.
Subject(s)
Dolphins , Humans , Animals , Virulence Factors/genetics , Ecosystem , Hemolysin Proteins , Siderophores , Gram-Negative Bacteria , Peptide HydrolasesABSTRACT
Notwithstanding the advances in molecular target-based drugs, chemotherapy remains the most common cancer treatment, despite its high toxicity. Consequently, effective anticancer therapies with fewer adverse effects are needed. Therefore, this study aimed to determine the anticancer activity of the dichloromethane fraction (DCMF) isolated from Arrabidae brachypoda roots, whose components are three unusual dimeric flavonoids. The toxicity of DCMF was investigated in breast (MCF-7), prostate (DU145), and cervical (HeLa) tumor cells, as well as non-tumor cells (PNT2), using sulforhodamine B (cell viability), Comet (genotoxicity), clonogenicity (reproductive capacity) and wound healing (cell migration) assays, and atomic force microscopy (AFM) for ultrastructural cell membrane alterations. Molecular docking revealed affinity between albumin and each rare flavonoid, supporting the impact of fetal bovine serum in DCMF antitumor activity. The IC50 values for MCF7, HeLa, and DU145 were 2.77, 2.46, and 2.51 µg/mL, respectively, and 4.08 µg/mL for PNT2. DCFM was not genotoxic to tumor or normal cells when exposed to twice the IC50 for up to 24 h, but it inhibited tumor cell migration and reproduction compared to normal cells. Additionally, AFM revealed alterations in the ultrastructure of tumor nuclear membrane surfaces, with a positive correlation between DCMF concentration and tumor cell roughness. Finally, we found a negative correlation between roughness and the ability of DCMF-treated tumor cells to migrate and form colonies with more than 50 cells. These findings suggest that DCFM acts by causing ultrastructural changes in tumor cell membranes while having fewer toxicological effects on normal cells.
Subject(s)
Flavonoids , Neoplasms , Male , Humans , Flavonoids/pharmacology , Flavonoids/chemistry , Molecular Docking Simulation , HeLa Cells , Cell Membrane , Cell Survival , Cell Line, TumorABSTRACT
Pyrazole and its derivatives are considered privileged N-heterocycles with immense therapeutic potential [...].
ABSTRACT
Hemotropic Mycoplasma spp. (hemoplasmas) are uncultivable bacteria that infect mammals, including humans. We detected a potentially novel hemoplasma species in blood samples from wild river dolphins in the Amazon River Basin, Brazil. Further investigation could determine pathogenicity and zoonotic potential of the detected hemoplasma.
Subject(s)
Mycoplasma Infections , Mycoplasma , Animals , Humans , Mycoplasma/genetics , Mycoplasma Infections/epidemiology , Mycoplasma Infections/veterinary , Mycoplasma Infections/microbiology , Brazil/epidemiology , Phylogeny , MammalsABSTRACT
Vinylpyrazoles, also known as pyrazolyl olefins, are interesting motifs in organic chemistry but have been overlooked. This review describes the properties and synthetic routes of vinylpyrazoles and highlights their versatility as building blocks for the construction of more complex organic molecules. Concerning the reactivity of vinylpyrazoles, the topics surveyed herein include their use in cycloaddition reactions, free-radical polymerizations, halogenation and hydrohalogenation reactions, and more recently in transition-metal-catalyzed reactions, among other transformations. The current state of the art about vinylpyrazoles is presented with an eye to future developments regarding the chemistry of these interesting compounds. Styrylpyrazoles were not considered in this review, as they were the subject of a previous review article published in 2020.
Subject(s)
Transition Elements , Cycloaddition ReactionABSTRACT
Acute myeloid leukemia (AML) comprises a heterogeneous group of hematopoietic cell neoplasms of myeloid lineage that arise from the clonal expansion of their precursors in the bone marrow, interfering with cell differentiation, leading to a syndrome of bone marrow failure. AML is a consequence of genetic and epigenetic changes (point mutations, gene rearrangements, deletions, amplifications, and arrangements in epigenetic changes that influence gene expression) in hematopoietic precursor cells, which create a clone of abnormal cells that are capable of proliferating but cannot differentiate into mature hematopoietic cells or undergo programmed cell death. The diagnosis requires more than 20% myeloid blasts in the bone marrow and certain cytogenic abnormalities. Treatment will depend on age, comorbidities, and cytogenetic risk among the most frequent.
La leucemia mieloide aguda (LMA) comprende un grupo heterogéneo de neoplasias de células hematopoyéticas de linaje mieloide que surgen de la expansión clonal de sus precursores en la médula ósea, interfiriendo con la diferenciación celular, lo que conlleva a un síndrome de falla medular. La LMA es una consecuencia de cambios genéticos y epigenéticos (mutaciones puntuales, rearreglos de genes, deleciones, amplificaciones y arreglos en cambios epigenéticos que influyen en la expression del gen) en las células hematopoyéticas precursoras, la cual crea una clona de células anormales que son capaces de proliferar, pero no se pueden diferenciar en células hematopoyéticas maduras ni sufrir una muerte celular programada. El diagnostic requiere más del 20% de blastos mieloides en médula ósea y ciertas anormalidades citogénicas. El tratamiento dependerá de la edad, comorbilidades, riesgo citogenético entre las más frecuentes.
Subject(s)
Leukemia, Myeloid, Acute , Cell Differentiation , Consensus , Humans , Leukemia, Myeloid, Acute/diagnosis , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/therapy , MexicoABSTRACT
Pyrazoles and their reduced form, pyrazolines, are considered privileged scaffolds in medicinal chemistry, owing to their remarkable biological activities, physicochemical properties and occurrence in many low-molecular-weight compounds present in several marketed drugs (e [...].
ABSTRACT
Hodgkin's lymphoma is due to the clonal transformation of cells originating from B lymphocytes, generating the pathognomonic binucleate Reed-Sternberg cells. Hodgkin's lymphoma is a B cell disease with a bimodal distribution, with higher incidence in adolescence and the third decade of life, showing a second peak in people over 55 years of age. Classic Hodgkin lymphoma cells routinely undergo gene expression reprogramming, as they lose the expression of most of the typical B-cell genes and acquire the expression of multiple genes that are typical of other types of cells in the immune system. The treatment algorithm will depend on whether it is classic or predominantly lymphocytic HL, if it is early stage with unfavorable prognostic markers or not, the initial management regimen, and whether there is bulky disease, among the most relevant variables.
El linfoma de Hodgkin (LH) se debe a la transformación clonal de células originadas en los linfocitos B, lo que genera las células binucleadas patognomónicas de Reed-Sternberg. El LH es una enfermedad de células B con una distribución bimodal, con mayor incidencia en la adolescencia y la tercera década de la vida y un segundo pico en personas mayores de 55 años. Las células del LH clásico habitualmente sufren una reprogramación de la expresión génica, ya que pierden la expresión de la mayoría de los genes típicos de las células B y han adquirido la expresión de múltiples genes que son típicos de otros tipos de células del sistema inmunitario. El algoritmo de tratamiento dependerá si se trata de LH clásico o de predominio linfocítico, si es un estadio temprano con marcadores de pronóstico desfavorables o no, el esquema inicial de manejo y si existe enfermedad voluminosa, entre las variables más relevantes.
Subject(s)
Consensus , Hodgkin Disease , Reed-Sternberg Cells , Age Distribution , Algorithms , Antineoplastic Agents/therapeutic use , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Gene Expression , Hodgkin Disease/drug therapy , Hodgkin Disease/epidemiology , Hodgkin Disease/genetics , Hodgkin Disease/pathology , Humans , Mexico , Neoplasm Staging , Positron Emission Tomography Computed Tomography , Reed-Sternberg Cells/pathologyABSTRACT
El linfoma de Hodgkin (LH) se debe a la transformación clonal de células originadas en los linfocitos B, lo que genera las células binucleadas patognomónicas de Reed-Sternberg. El LH es una enfermedad de células B con una distribución bimodal, con mayor incidencia en la adolescencia y la tercera década de la vida y un segundo pico en personas mayores de 55 años. Las células del LH clásico habitualmente sufren una reprogramación de la expresión génica, ya que pierden la expresión de la mayoría de los genes típicos de las células B y han adquirido la expresión de múltiples genes que son típicos de otros tipos de células del sistema inmunitario. El algoritmo de tratamiento dependerá si se trata de LH clásico o de predominio linfocítico, si es un estadio temprano con marcadores de pronóstico desfavorables o no, el esquema inicial de manejo y si existe enfermedad voluminosa, entre las variables más relevantes.Hodgkin's lymphoma (HL) is due to the clonal transformation of cells originating from B lymphocytes, generating the pathognomonic binucleate Reed-Sternberg cells. HL is a B cell disease with a bimodal distribution, with higher incidence in adolescence and the third decade of life, showing a second peak in people over 55 years of age. Classic Hodgkin lymphoma cells routinely undergo gene expression reprogramming, as they lose the expression of most of the typical B-cell genes and acquire the expression of multiple genes that are typical of other types of cells in the immune system. The treatment algorithm will depend on whether it is classic or predominantly lymphocytic HL, if it is early stage with unfavorable prognostic markers or not, the initial management regimen, and whether there is bulky disease, among the most relevant variables.
Subject(s)
Consensus , Hodgkin Disease , Age Factors , Algorithms , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Cell Transformation, Neoplastic/pathology , Hodgkin Disease/genetics , Hodgkin Disease/pathology , Hodgkin Disease/therapy , Humans , Immunotherapy/methods , Lymphoma, AIDS-Related/etiology , Mexico , Neoplasm Staging , Positron Emission Tomography Computed Tomography , Prognosis , Reed-Sternberg Cells/pathologyABSTRACT
Hemophilia is a hemorrhagic disorder with a sex-linked inherited pattern, characterized by an inability to amplify coagulation due to a deficiency in coagulation factor VIII (hemophilia A or classic) or factor IX (hemophilia B). Sequencing of the genes involved in hemophilia has provided a description and record of the main mutations, as well as a correlation with the various degrees of severity. Hemorrhagic manifestations are related to levels of circulating factor, mainly affecting the musculoskeletal system and specifically the large joints (knees, ankles, and elbows). This document is a review and consensus of the main genetic aspects of hemophilia, from the inheritance pattern to the concept of women carriers, physiopathology and classification of the disorder, the basic and confirmation studies when hemophilia is suspected, the various treatment regimens based on infusion of the deficient coagulation factor as well as innovative factor-free therapies and recommendations for the management of complications associated with treatment (development of inhibitors and/or transfusion-transmitted infections), or secondary to articular hemorrhagic events (hemophilic arthropathy). Finally, relevant reviews of clinical and treatment aspects of hemorrhagic pathology characterized by acquired deficiency of FVIII secondary to neutralized antibodies named acquired hemophilia.
La hemofilia es un trastorno hemorrágico con patrón de herencia ligado al sexo, caracterizado por una incapacidad en la amplificación de la coagulación ocasionada por la deficiencia del factor VIII (hemofilia A o clásica) o del factor IX (hemofilia B). La secuenciación de los genes involucrados en la hemofilia ha permitido la descripción y registro de las principales mutaciones, así como la correlación con los diversos grados de severidad. Las manifestaciones hemorrágicas se relacionan con los niveles de factor deficiente circulante, afectando principalmente al sistema musculoesquelético y en particular a las grandes articulaciones (rodillas, tobillos y codos). El presente documento hace una revisión y consenso de los principales aspectos genéticos de la hemofilia, desde el patrón de herencia y el concepto de mujeres portadoras, la fisiopatología y clasificación de la enfermedad, los estudios básicos y de confirmación ante la sospecha de hemofilia, y de los diversos esquemas de tratamiento basados en la infusión del factor de coagulación deficiente hasta las terapias innovadoras libres de factor, así como de las recomendaciones para el manejo de las complicaciones asociadas al tratamiento (desarrollo de inhibidores y/o infecciones transmitidas por transfusión) o secundarias a los eventos hemorrágicos a nivel articular (artropatía hemofílica). La parte final del documento revisa los aspectos clínicos y de tratamiento relevantes de una patología hemorragica caracterizada por la deficiencia adquirida del FVIII mediada por anticuerpos neutralizantes denominada hemofilia adquirida.
Subject(s)
Hemophilia A , Algorithms , Hemophilia A/diagnosis , Hemophilia A/etiology , Hemophilia A/therapy , MexicoABSTRACT
Several epidemiological studies indicate that neutrophils, under hyperglycemic conditions, are involved in the perpetuation of the inflammatory status, a characteristic of diabetes mellitus, leading to the production of prodigious quantities of reactive species and the release of neutrophil extracellular traps (NETs). Accordingly, our aim was to study the ability of a panel of 25 structurally related chalcones to modulate human neutrophil oxidative burst and the production of NETs under physiological and high glucose conditions. In general, all chalcones presented similar effects under physiological and high glucose conditions. 2',4-Dihydroxy-3-methoxychalcone (3), here studied for the first time, was the most active (IC50 ≤ 5 µM) on the inhibition of neutrophil oxidative burst, showing the importance of the presence of hydroxy substituents at the C-2' and C-4 positions of the A and B rings, respectively, and a 3-methoxy substituent at B ring of the chalcone scaffold. In the present experimental conditions, NETs release only occurred under high glucose levels. The pentahydroxylated chalcone 1 was the only one that was able to modulate the NETs release. This study provided important considerations about the chalcones' scaffold and their modulatory effect on human neutrophil activities at physiological and high glucose conditions, evidencing their potential use as complementary antidiabetic agents.
Subject(s)
Chalcones/pharmacology , Glucose/pharmacology , Neutrophils/drug effects , Neutrophils/metabolism , Respiratory Burst/drug effects , Adolescent , Adult , Aged , Cell Survival/drug effects , Extracellular Traps/drug effects , Extracellular Traps/metabolism , Female , Humans , Hypoglycemic Agents/pharmacology , Male , Middle Aged , Molecular Structure , Reactive Oxygen Species/metabolism , Spectrophotometry, Ultraviolet , Structure-Activity Relationship , Young AdultABSTRACT
In order to meet the increasing demand for environmentally benign chemical processes, we developed a Suzuki-Miyaura reaction protocol based on the combination of ohmic heating (ΩH) and supported ionic liquid phase catalysis (SILPC) in aqueous media. This methodology was applied to the synthesis of a series of flavonoid derivatives, including isoflavones, styrylisoflavones, and diarylalkenylisoflavones.
Subject(s)
Ionic Liquids/chemistry , Isoflavones/chemical synthesis , Palladium/chemistry , Water/chemistry , Boronic Acids/chemistry , Catalysis , Chromones/chemistry , Green Chemistry Technology , HeatingABSTRACT
The need for increasingly personalized medicine solutions (precision medicine) and quality medical treatments, has led to a growing demand and research for image-guided therapeutic solutions. Positron emission tomography (PET) is a powerful imaging technique that can be established using complementary imaging systems and selective imaging agents-chemical probes or radiotracers-which are drugs labeled with a radionuclide, also called radiopharmaceuticals. PET has two complementary purposes: selective imaging for diagnosis and monitoring of disease progression and response to treatment. The development of selective imaging agents is a growing research area, with a high number of diverse drugs, labeled with different radionuclides, being reported nowadays. This review article is focused on the use of pyrazoles as suitable scaffolds for the development of 18F-labeled radiotracers for PET imaging. A brief introduction to PET and pyrazoles, as key scaffolds in medicinal chemistry, is presented, followed by a description of the most important [18F]pyrazole-derived radiotracers (PET tracers) that have been developed in the last 20 years for selective PET imaging, grouped according to their specific targets.
Subject(s)
Fluorine Radioisotopes/chemistry , Positron-Emission Tomography , Pyrazoles/chemistry , Radioactive Tracers , Radiopharmaceuticals/chemistry , Animals , Drug Development , Humans , Ligands , Positron-Emission Tomography/methods , Protein Binding , Structure-Activity RelationshipABSTRACT
The pyrazole nucleus and its reduced forms, pyrazolines and pyrazolidine, are privileged scaffolds in medicinal chemistry due to their remarkable biological activities. A huge number of pyrazole derivatives have been studied and reported over time. This review article gives an overview of pyrazole derivatives that contain a styryl (2-arylvinyl) group linked in different positions of the pyrazole backbone. Although there are studies on the synthesis of styrylpyrazoles dating back to the 1970s and even earlier, this type of compound has rarely been studied. This timely review intends to summarize the properties, biological activity, methods of synthesis and transformation of styrylpyrazoles; thus, highlighting the interest and huge potential for application of this kind of compound.
Subject(s)
Pyrazoles/chemistry , Animals , Humans , Molecular Structure , Pyrazoles/chemical synthesis , Pyrazoles/pharmacologyABSTRACT
The present review presents an overview of antitumor pyrazoles of natural or bioinspired origins. Pyrazole compounds are relatively rare in nature, the first ones having been reported in 1966 and being essentially used as somniferous drugs. Cytotoxic pyrazoles of natural sources were first isolated in 1969, and a few others have been reported since then, most of them in the last decade. This paper presents a perspective on the current knowledge on antitumor natural pyrazoles, organized into two sections. The first focuses on the three known families of cytotoxic pyrazoles that were directly isolated from plants, for which the knowledge of the medicinal properties is in its infancy. The second section describes pyrazole derivatives of natural products, discussing their structure-activity relationships.
Subject(s)
Antineoplastic Agents/pharmacology , Biological Products/pharmacology , Biomimetic Materials/pharmacology , Pyrazoles/pharmacology , Animals , Antineoplastic Agents/chemistry , Biological Products/chemistry , Biomimetic Materials/chemistry , Humans , Pyrazoles/chemistryABSTRACT
A series of pyridyl analogues of rosamines was prepared by employing two methodologies: (i)â the conventional-heating condensation of a pyridinecarboxaldehyde with 3-(diethylamino)phenol in propionic acid, and (ii)â the novel ohmic-heating assisted condensation under "on water" conditions, followed by oxidation. The 4-pyridyl substituted rosamine was further converted into the N-methylpyridinium derivative through N-alkylation using methyl iodide. The influence of the position and cationization of the nitrogen atom of the pyridyl ring in the physicochemical properties of fluorophores was investigated by 1 H, 13 C, 15 Nâ NMR spectral analysis, UV/Vis and fluorescence spectroscopy, single-crystal X-ray diffraction (4-pyridyl and N-methylpyridinium derivatives) and thermal-behavior analysis. Curiously, for ethanolic solutions of 4-pyridyl and N-methylpyridinium derivatives an extinction of color and fluorescence over time was observed. This phenomenon was further studied and the data revealed that it is the result of nucleophilic addition of ethoxide ion to the central 9-position of the xanthene. The kinetics of the process is slower for the 4-pyridyl rosamine, which emphasizes the importance of the charge in the N-methylpyridinium analogue in the reactivity of the molecule towards a nucleophile agent. This phenomenon is reversible, meaning that the compounds can be rapidly recovered by decreasing the pH, opening new avenues in the sensing applications of this class of rosamines.