Showing: 10 from total: 652 publications
1. Assessment of Surface Water Quality Using the Water Quality Index (IWQ), Multivariate Statistical Analysis (MSA) and Geographic Information System (GIS) in Oued Laou Mediterranean Watershed, Morocco
Azhari, HE ; Cherif, EK ; Sarti, O ; Azzirgue, EM ; Dakak, H ; Yachou, H ; Esteves da Silva, JCG ; Salmoun, F
in Water (Switzerland), 2023, ISSN: 2073-4441,  Volume: 15, 
Article,  Indexed in: crossref, scopus 
Abstract Surface water is used for a variety of purposes, including agriculture, drinking water, and other services. Therefore, its quality is crucial for irrigation, human welfare, and health. Thus, the main objective is to improve surface water quality assessment and geochemical analysis to evaluate anthropogenic activities’ impact on surface water quality in the Oued Laou watershed, Northern Morocco. Thirteen surface water samples were characterized for 26 physicochemical and biological parameters. In this aspect, emerging techniques such as multivariate statistical approaches (MSA), water quality indices (WQI), irrigation water quality (IWQI), and Geographic Information System (GIS) were employed to identify the sources of surface water pollution, their suitability for consumption, and the distribution of surface water quality. The results showed that the major ion concentrations were reported in the following order: Ca2+, Na+, Mg2+, and K+; and HCO3− > CO32− > Cl− > SO42− > NO3− > F− > PO43− > NO2−. It was also demonstrated that almost all parameters had concentrations lower than World Health Organization (WHO) limits, except for bicarbonate ions (HCO3−) and the biochemical oxygen demand for five days (BOD5), which exceeded the WHO limits at 120 mg/L and 3 mg/L, respectively. Furthermore, the types of Ca2+-HCO3− (Calcium-Bicarbonate) and Ca2+-Mg2+-HCO3− (Calcium-Magnesium-Bicarbonate) predominated in surface water. The Principal Component Analysis (PCA) indicates that the Oued Laou river was exposed to two forms of contamination, the first being attributed to anthropogenic activities such as agriculture, while the second reflects the water-sediment interaction. The Hierarchical Cluster Analysis (HCA), reflecting the mineralization in the study area, has classified the samples into four clusters. The Inverse Distance Weighting (IDW) of the WQI indicates that 7.69% and 38.46% of the surface water represent, respectively, excellent and good quality for drinking. At the same time, the IWQI revealed that 92.30% of the water surface is good for irrigation. As a result, the combination of WQIs, PCA, IWQI, and GIS techniques is effective in providing clear information for assessing the suitability of surface water for drinking and its controlling factors and can also support decision-making in susceptible locations such as the Oued Laou river in northern Morocco. © 2022 by the authors.

2. Phytochemical Compounds and Anticancer Activity of Cladanthus mixtus Extracts from Northern Morocco
El Mihyaoui, A ; Charfi, S ; Erbiai, EH ; Pereira, M ; Duarte, D ; Vale, N ; Candela Castillo, ME ; Badoc, A ; Lamarti, A ; Esteves da Silva, JCG ; Arnao, MB
in Cancers, 2023, ISSN: 2072-6694,  Volume: 15, 
Article,  Indexed in: crossref, scopus 
Abstract Many of the chemotherapeutic drugs for the treatment of cancer are molecules identified and isolated from plants or their synthetic derivatives. This work aimed to identify the bioactive compounds using LC-MS and GC-MS and to evaluate the anticancer activity of the methanolic extracts of roots, stems, leaves, and flowers from Cladanthus mixtus. The anticancer activity was evaluated in vitro against two cancer cell lines: human breast carcinoma (MCF-7) and human prostate carcinoma (PC-3), using the MTT assay and microscopic observation. A human normal lung fibroblast (MRC-5) was included to determine the extract’s safety for non-tumoral cells. The chemical composition results by LC-MS analysis revealed the presence of 24 phenolic compounds. Furthermore, GC-MS analysis allowed the identification of many biomolecules belonging to terpenoids, esters, alcohols, alkanes, fatty acids, organic acids, benzenes, phenols, ketones, carbonyls, amines, sterols, and other groups. The findings suggest that the majority of C. mixtus extracts have antiproliferative activity against two cancer cell lines, MCF-7 and PC-3, and one non-tumoral cell line, MRC-5. The activity was dose-dependent, and the highest effect was obtained with leaf extract in the two cancer cell lines. Moreover, these extracts demonstrated an acceptable toxicological profile against normal cells. Overall, C. mixtus extracts revealed promising antitumor properties provided by their phytochemical composition. © 2022 by the authors.

3. 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 
Abstract <jats:p>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.</jats:p>

4. Nanoporous anodic alumina layers obtained from novel deep eutectic solvent formulations
Fernandes, PMV ; Brincoveanu, O ; Pantazi, A ; Petica, A ; Pereira, CM ; Silva, AF ; Enachescu, M ; Anicai, L
in TRANSACTIONS OF THE INSTITUTE OF METAL FINISHING, 2022, ISSN: 0020-2967, 
Article in Press,  Indexed in: crossref, scopus, unpaywall, wos 
Abstract The possible fabrication of porous anodic oxide films on aluminium in ionic liquids based on choline dihydrogen citrate eutectic mixtures both with oxalic acid and isopropyl alcohol and ethylene glycol, has been investigated. The anodisation has been carried out in either potentiostatic or galvanostatic regime, at temperatures of 45-80 degrees C, for different process durations. Quite compact, uniform anodic alumina layers have been obtained. Based on AFM and SEM investigations, pore diameters between 50 and 80 nm and interpore distances in the range of 160-200 nm have been estimated, with values influenced by the electrolyte type and anodisation conditions. The highest anodisation rate of about 0.4 mu m min(-1) has been determined by applying operation temperatures of 60 degrees C. The recorded EIS spectra showed a pure capacitive behaviour and high anodic oxide resistances of 10(6)-10(7) omega cm(2) order.

5. 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>

6. 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.

7. 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.

8. 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.

9. Rationalizing the role of electron/charge transfer in the intramolecular chemiexcitation of dioxetanone-based chemi-/bioluminescent systems
da Silva, LP ; da Silva, JE
in JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY, 2022, ISSN: 1010-6030,  Volume: 429, 
Article,  Indexed in: crossref, scopus, wos 
Abstract The thermolysis of dioxetanones is a key process in the intramolecular chemiexcitation step of several chemi-and bioluminescent reactions. This step is generally explained with mechanisms based on either electron transfer (ET), such as the Chemically Initiated Electron-Exchange Luminescence (CIEEL) mechanism, or charge transfer (CT), such as the Charge Transfer-Initiated Luminescence (CTIL) mechanism. Here, we have used a TD-DFT approach to characterize the thermolysis and chemiexcitation steps of model dioxetanones, to rationalize the role of ET/CT in those intramolecular processes. Our results showed that ET/CT can reduce the activation barrier of the thermolysis reaction, by reducing the repulsion between the reacting fragments (ketone and CO2 moieties) that originate during peroxide bond breaking. However, in terms of singlet chemiexcitation profiles, those of non-CIEEL/CTIL-based dioxetanones appear to be more efficient than of CIEEL/CTIL-based ones. Furthermore, the ground state to singlet excited state transitions were found to be local excitations, without CT between the peroxide ring and the electron-rich moiety. So, ET/CT appear to be responsible for tuning the activation barrier of the thermolysis reaction, without playing a role in efficient singlet chemiexcitation itself.

10. Theoretical Study of the Thermolysis Reaction and Chemiexcitation of Coelenterazine Dioxetanes
Magalhaes, CM ; da Silva, JCGE ; da Silva, LP
in JOURNAL OF PHYSICAL CHEMISTRY A, 2022, ISSN: 1089-5639,  Volume: 126, 
Article,  Indexed in: crossref, scopus, wos 
Abstract Coelenterazine and other imidazopyrazinones are important bioluminescent substrates widespread in marine species and can be found in eight phyla of luminescent organisms. Light emission from these systems is caused by the formation and subsequent thermolysis of a dioxetanone intermediate, whose decomposition allows for efficient chemiexcitation to singlet excited states. Interestingly, some studies have also reported the involvement of unexpected dioxetane intermediates in the chemiand bioluminescent reactions of Coelenterazine, albeit with little information on the underlying mechanisms of these new species. Herein, we have employed a theoretical approach based on density functional theory to study for the first time the thermolysis reaction and chemiexcitation profile of two Coelenterazine dioxetanes. We have found that the thermolysis reactions of these species are feasible but with relevant energetic differences. More importantly, we found that the singlet chemiexcitation profiles of these dioxetanes are significantly less efficient than the corresponding dioxetanones. Furthermore, we identified triplet chemiexcitation pathways for the Coelenterazine dioxetanes. Given this, the chemiexcitation of these dioxetanes should lead only to minimal luminescence. Thus, our theoretical investigation of these systems indicates that the thermolysis of these dioxetanes should only provide dark pathways for the formation of nonluminescent degradation products of the chemi- and bioluminescent reactions of Coelenterazine and other imidazopyrazinones.