Showing: 10 from total: 2087 publications
61. Effects of Exogenously Applied Copper in Tomato Plants' Oxidative and Nitrogen Metabolisms under Organic Farming Conditions
Alves, A ; Ribeiro, R ; Azenha, M ; Cunha, M ; Teixeira, J
in HORTICULTURAE, 2023, ISSN: 2311-7524,  Volume: 9, 
Article,  Indexed in: crossref, scopus, wos 
Abstract Currently, copper is approved as an active substance among plant protection products and is considered effective against more than 50 different diseases in different crops, conventional and organic. Tomato has been cultivated for centuries, but many fungal diseases still affect it, making it necessary to control them through antifungal agents, such as copper, making it the primary form of fungal control in organic farming systems (OFS). The objective of this work was to determine whether exogenous copper applications can affect AOX mechanisms and nitrogen use efficiency in tomato plant grown in OFS. For this purpose, plants were sprayed with 'Bordeaux' mixture (SP). In addition, two sets of plants were each treated with 8 mg/L copper in the root substrate (S). Subsequently, one of these groups was also sprayed with a solution of 'Bordeaux' mixture (SSP). Leaves and roots were used to determine NR, GS and GDH activities, as well as proline, H2O2 and AsA levels. The data gathered show that even small amounts of copper in the rhizosphere and copper spraying can lead to stress responses in tomato, with increases in total ascorbate of up to 70% and a decrease in GS activity down to 49%, suggesting that excess copper application could be potentially harmful in horticultural production by OFS.

62. 2,4-dichlorophenoxyacetic acid detoxification occurs primarily in tomato leaves by the glutathione S-transferase phi members 4 and 5
Pinto, A ; Azenha, M ; Fidalgo, F ; Teixeira, J
in SCIENTIA HORTICULTURAE, 2023, ISSN: 0304-4238,  Volume: 321, 
Article,  Indexed in: crossref, scopus, unpaywall, wos 
Abstract In the last 60 years, auxinic herbicides like 2,4-dichlorophenoxyacetic acid (2,4-D) have been among the widest and successful herbicides used in agriculture because it is a selective herbicide that kills dicots and mimics the natural plant phytohormone indol-3-acetic acid (IAA) at the molecular level. In spite of industry attempts to reformulate 2,4-D-based herbicides and reduce their off-target movement, damage has been reported on sensitive plants, like tomato, at low ratesdi. Therefore, it is important to study the responses of such species to such conditions so that yield losses can be avoided or, at least, reduced. It is known that ethylene, abscisic acid (ABA) and reactive oxygen species (ROS) play a central role in 2,4-D toxicity, leading to numerous unbeneficial changes in plant tissues. Yet, how glutathione-related defense-and/or stress-related genes' expressions are affected needs to be more studied. In this study, tomato plants (Solanum lycopersicum L.) were used to determine the expression and participation of the different GST phi class gene family members, plus the plans' antioxidant system, in response to 2,4-D. When tomato plants were root-treated with 2.26 mM 2,4-D for 48 h, H2O2 and O2 & BULL; levels increased in shoots. Contrarily, in roots, 2,4-D did not provoke clear symptoms of oxidative stress, as lipid peroxidation, H2O2 and O2 & BULL; levels decreased. Despite the difference in ROS levels observed in both organs, the exposure of tomato plants to 2,4-D lead to the activation of key antioxidant enzymes in both organs, apart from superoxide dismutase (SOD), whose activity increased only in roots, while ascorbate peroxidase (APX) and catalase (CAT) activities increased in both. Also, tomato plants responded to 2.26 mM 2,4-D by increasing Ascorbate (AsA) levels in both organs while an increase in Glutathione (GSH) was only observed in shoots. The herbicide increased both the synthesis and the regeneration of GSH, as well as its usage to conjugate 2,4-D, as shoot & gamma;-glutamyl-cysteinyl synthetase (& gamma;-ECS), glutathione reductase (GR) and glutathione S-transferase (GST) activities increased. Shoot GST increased activity was due to an increased expression of SlGSTF4 and SlGSTF5, while no SlGSTFs increased their expression in roots. Shoots and roots of tomato plants were differentially affected by 2.26 mM 2,4-D, with 2,4-D detoxification occurring predominantly in leaves, with the specific participation of the GST phi class members SlGSTF4 and SlGSTF5. Also, this study reinforces the notion that the cultivation of tomato in 2,4-D-contaminated soils may result in yield reduction.

63. Isothermal titration calorimetry
Bastos, M ; Abian, O ; Johnson, CM ; Ferreira-da-Silva, F ; Vega, S ; Jimenez-Alesanco, A ; Ortega-Alarcon, D ; Velazquez-Campoy, A
in NATURE REVIEWS METHODS PRIMERS, 2023, ISSN: 2662-8449,  Volume: 3, 
Article,  Indexed in: crossref, scopus, wos 
Abstract Isothermal titration calorimetry (ITC) has become the gold standard for studying molecular interactions in solution. Although it is increasingly being used in the soft matter and synthetic chemistry fields, ITC is most widely used for characterizing molecular interactions between ligands and macromolecules. This Primer starts by presenting the technique's foundations and instrumentation, including a brief description of the standard assay, followed by a review of common applications. Further extensions and modifications of the technique are explored. These adaptations enable key features to be studied, such as cooperative effects associated with complex biological interactions and their regulation, alongside applications to other fields, including partition to membranes, kinetics and soft matter. Advantages and caveats in ITC are discussed, with a focus on best practices, instrument calibration, experimental design, data analysis and data reporting, as well as recent and future developments.

64. Determination and Analysis of Thermodynamic Properties of Methyl Methylanthranilate Isomers
Silva, CAO ; Freitas, VLS ; da Silva, MDMCR
in MOLECULES, 2023, ISSN: 1420-3049,  Volume: 28, 
Article,  Indexed in: crossref, scopus, wos 
Abstract The enthalpies of formation in the gaseous phase of methyl 3-methylanthranilate and methyl 5-methylanthranilate were determined from experimental measurements of the corresponding standard energies of combustion, obtained from combustion calorimetry, and the standard enthalpies of vaporization and sublimation, obtained from Calvet microcalorimetry and Knudsen mass-loss effusion. A computational study, using the G3(MP2)//B3LYP composite method, has also been performed for the calculation of the gas-phase standard enthalpies of formation of those two molecules at T = 298.15 K, as well as for the remaining isomers, methyl 4-methylanthranilate and methyl 6-methylanthranilate. The results have been used to evaluate and analyze the energetic effect of the methyl substituent in different positions of the ring.

65. Preparation, Characterization, and Environmental Safety Assessment of Dithiocarbazate Loaded Mesoporous Silica Nanoparticles
Menezes, T ; Bouguerra, S ; Andreani, T ; Pereira, R ; Pereira, C
in NANOMATERIALS, 2023, Volume: 13, 
Article,  Indexed in: crossref, scopus, wos 
Abstract Dithiocarbazates comprise an important class of Schiff bases with remarkable biological applications due to the imine group present in their structure. However, full exploitation of the biological activity of 3-methyl-5-phenyl-pyrazoline-1-(S-benzyldithiocarbazate) (DTC) is limited due to its easy degradation and poor solubility in aqueous solutions. The loading of DTC into mesoporous silica nanoparticles (MSiNPs) can be an excellent strategy to improve the solubility of DTC in the aqueous medium. Therefore, the main goal of the present work was to design MSiNP-DTC and to evaluate the success of the loading process by measuring its physicochemical properties and evaluating the environmental safety of the new DTC formulation using different aquatic organisms, such as the microalgae Raphidocelis subcapitata, the macrophyte Lemna minor, and the marine bacterium Aliivibrio fischeri. DTC, MSiNP, and MSiNP-DTC concentrations ranging from 8.8 to 150 mg L-1 were tested for all the species, showing low toxicity against aquatic organisms. Loading DTC into MSiNPs caused a slight increase in the toxicity at the concentrations tested, only allowing for the estimation of the effect concentration causing a 20% reduction in bioluminescence or growth rate (EC20). Therefore, despite the potential of MSiNPs as a drug delivery system (DDS), it is of utmost importance to assess its impact on the safety of the new formulations.

66. Discovery of the Anticancer Activity for Lung and Gastric Cancer of a Brominated Coelenteramine Analog
González-Berdullas, P ; Pereira, RB ; Teixeira, C ; Silva, JP ; Magalhães, CM ; Rodríguez-Borges, JE ; Pereira, DM ; Esteves da Silva, JCG ; Pinto da Silva, L
in International Journal of Molecular Sciences, 2022, Volume: 23, 
Article,  Indexed in: crossref 
Abstract <jats:p>Cancer is still a challenging disease to treat, both in terms of harmful side effects and therapeutic efficiency of the available treatments. Herein, to develop new therapeutic molecules, we have investigated the anticancer activity of halogenated derivatives of different components of the bioluminescent system of marine Coelenterazine: Coelenterazine (Clz) itself, Coelenteramide (Clmd), and Coelenteramine (Clm). We have found that Clz derivatives possess variable anticancer activity toward gastric and lung cancer. Interestingly, we also found that both brominated Clmd (Br-Clmd) and Clm (Br-Clm) were the most potent anticancer compounds toward these cell lines, with this being the first report of the anticancer potential of these types of molecules. Interestingly, Br-Clm possessed some safety profile towards noncancer cells. Further evaluation revealed that the latter compound induced cell death via apoptosis, with evidence for crosstalk between intrinsic and extrinsic pathways. Finally, a thorough exploration of the chemical space of the studied Br-Clm helped identify the structural features responsible for its observed anticancer activity. In conclusion, a new type of compounds with anticancer activity toward gastric and lung cancer was reported and characterized, which showed interesting properties to be considered as a starting point for future optimizations towards obtaining suitable chemotherapeutic agents.</jats:p>

67. Comparative Investigation of the Chemiluminescent Properties of a Dibrominated Coelenterazine Analog
Sousa, J ; Magalhaes, CM ; Gonzalez-Berdullas, P ; da Silva, JCGE ; da Silva, LP
in INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES, 2022, ISSN: 1422-0067,  Volume: 23, 
Article,  Indexed in: crossref, scopus, wos 
Abstract Chemi- and bioluminescence are remarkable light-emitting phenomena, in which thermal energy is converted into excitation energy due to a (bio)chemical reaction. Among a wide variety of chemi-/bioluminescent systems, one of the most well-known and studied systems is that of marine imidazopyrazinones, such as Coelenterazine and Cypridina luciferin. Due to the increasing usefulness of their chemi-/bioluminescent reactions in terms of imaging and sensing applications, among others, significant effort has been made over the years by researchers to develop new derivatives with enhanced properties. Herein, we report the synthesis and chemiluminescent characterization of a novel dibrominated Coelenterazine analog. This novel compound consistently showed superior luminescence, in terms of total light output and emission lifetime, to natural imidazopyrazinones and commercially available analogs in aprotic media, while being capable of yellow light emission. Finally, this new compound showed enhanced chemiluminescence in an aqueous solution when triggered by superoxide anion, showing potential to be used as a basis for optimized probes for reactive oxygen species. In conclusion, bromination of the imidazopyrazinone scaffold appears to be a suitable strategy for obtaining Coelenterazines with enhanced properties.

68. Discovery of the Anticancer Activity for Lung and Gastric Cancer of a Brominated Coelenteramine Analog
Gonzalez Berdullas, P ; Pereira, RB ; Teixeira, C ; Silva, JP ; Magalhaes, CM ; Rodriguez Borges, JE ; Pereira, DM ; da Silva, JCGE ; da Silva, LP
in INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES, 2022, ISSN: 1422-0067,  Volume: 23, 
Article,  Indexed in: scopus, wos 
Abstract Cancer is still a challenging disease to treat, both in terms of harmful side effects and therapeutic efficiency of the available treatments. Herein, to develop new therapeutic molecules, we have investigated the anticancer activity of halogenated derivatives of different components of the bioluminescent system of marine Coelenterazine: Coelenterazine (Clz) itself, Coelenteramide (Clmd), and Coelenteramine (Clm). We have found that Clz derivatives possess variable anticancer activity toward gastric and lung cancer. Interestingly, we also found that both brominated Clmd (Br-Clmd) and Clm (Br-Clm) were the most potent anticancer compounds toward these cell lines, with this being the first report of the anticancer potential of these types of molecules. Interestingly, Br-Clm possessed some safety profile towards noncancer cells. Further evaluation revealed that the latter compound induced cell death via apoptosis, with evidence for crosstalk between intrinsic and extrinsic pathways. Finally, a thorough exploration of the chemical space of the studied Br-Clm helped identify the structural features responsible for its observed anticancer activity. In conclusion, a new type of compounds with anticancer activity toward gastric and lung cancer was reported and characterized, which showed interesting properties to be considered as a starting point for future optimizations towards obtaining suitable chemotherapeutic agents.

69. Boosting caffeic acid performance as antioxidant and monoamine oxidase B/catechol-O-methyltransferase inhibitor
Chavarria, D ; Benfeito, S ; Soares, P ; Lima, C ; Garrido, J ; Serra, P ; Soares da Silva, P ; Remia, F ; Oliveira, PJ ; Borges, F
in EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY, 2022, ISSN: 0223-5234,  Volume: 243, 
Article,  Indexed in: crossref, scopus, wos 
Abstract Increased oxidative stress (OS) and depletion of nigrostriatal dopamine (DA) are closely linked to the neuro-degeneration observed in Parkinson's Disease (PD). Caffeic acid (CA)-based antioxidants were developed, and their inhibitory activities towards monoamine oxidases (MAOs) and catechol O-methyltransferases (COMT) were screened. The results showed that the incorporation of an extra double bond maintained or even boosted the antioxidant properties of CA. alpha-CN derivatives displayed redox potentials (Ep) similar to CA (1) and inhibited hMAO-B with low mu M IC50 values. Moreover, catechol amides acted as MB-COMT inhibitors, showing IC50 values within the low mu M range. In general, CA derivatives presented safe cytotoxicity profiles at concentrations up to 10 mu M. The formation of reactive oxygen species (ROS) induced by CA derivatives may be underlying the cytotoxic effects observed at higher concentrations. Catechol amides 3-6, 8-11 at 10 mu M protected cells against oxidative damage. Compounds 3 and 8 were predicted to cross the blood-brain barrier (BBB) by passive diffu-sion. In summary, we report for the first time BBB-permeant CA-based multitarget lead compounds that may restore DAergic neurotransmission (dual hMAO-B/MB-COMT inhibition) and prevent oxidative damage. The data represents a groundbreaking advancement towards the discovery of the next generation of new drugs for PD.

70. Tuning the Intramolecular Chemiexcitation of Neutral Dioxetanones by Interaction with Ionic Species
Magalhães, CM ; da Silva, JCGE ; da Silva, LP
in Molecules, 2022, ISSN: 1420-3049,  Volume: 27, 
Article,  Indexed in: crossref, scopus 
Abstract The intramolecular chemiexcitation of high-energy peroxide intermediates, such as dioxe-tanones, is an essential step in different chemi-and bioluminescent reactions. Here, we employed the Time-Dependent Density Functional Theory (TD-DFT) methodology to evaluate if and how external stimuli tune the intramolecular chemiexcitation of model dioxetanones. More specifically, we evaluated whether the strategic placement of ionic species near a neutral dioxetanone model could tune its thermolysis and chemiexcitation profile. We found that these ionic species allow for the “dark” catalysis of the thermolysis reaction by reducing the activation barrier to values low enough to be compatible with efficient chemi-and bioluminescent reactions. Furthermore, while the inclusion of these species negatively affected the chemiexcitation profile compared with neutral dioxetanones, these profiles appear to be at least as efficient as anionic dioxetanones. Thus, our results demonstrated that the intramolecular chemiexcitation of neutral dioxetanones can be tuned by external stimuli in such a way that their activation barriers are decreased. Thus, these results could help to reconcile findings that neutral dioxetanones could be responsible for efficient chemi-/bioluminescence, while being typically associated with high activation parameters. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.