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Chemistry, Volume 6, Issue 2 (April 2024) – 7 articles

Cover Story (view full-size image): Global antimicrobial resistance has encouraged efforts to evaluate new drug candidates, such as ocellatins, a group of antimicrobial peptides found in the skin secretions of anurans of the Leptodactylidae family. This paper reports the isolation of a new ocellatin from the species Leptodactylus vastus. The peptide was called ocellatin-VT and especially inhibited Gram-negative bacteria growth, with the most activity against Acinetobacter baumannii and Escherichia coli. Ocellatin-VT was weakly cytotoxic to B16-F10 cancer cells and showed low-level hemolytic activity. Thus, a new ocellatin was isolated from L. vastus skin secretions that was active against non-resistant and multidrug-resistant bacteria. View this paper
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12 pages, 3837 KiB  
Article
First Report of Ocellatin-VT from the Skin Secretion of Leptodactylus vastus Lutz (Amphibia: Leptodactylidae)
by Tulíbia Laurindo Silva, Géssica Gomes Barbosa, Carlos José Correia de Santana, Patrícia Maria Guedes Paiva, Mariana S. Castro and Thiago Henrique Napoleão
Chemistry 2024, 6(2), 333-344; https://0-doi-org.brum.beds.ac.uk/10.3390/chemistry6020019 - 8 Apr 2024
Viewed by 841
Abstract
The global emergency of antimicrobial resistance has drawn several efforts to evaluate new drug candidates, such as natural defensive biomolecules. Ocellatins are a group of antimicrobial peptides found in anurans of the Leptodactylidae family. This work investigated the presence of antimicrobial peptides in [...] Read more.
The global emergency of antimicrobial resistance has drawn several efforts to evaluate new drug candidates, such as natural defensive biomolecules. Ocellatins are a group of antimicrobial peptides found in anurans of the Leptodactylidae family. This work investigated the presence of antimicrobial peptides in the skin secretion of Leptodactylus vastus from the Brazilian northeast. The secretion was fractionated by RP-HPLC, and the fractions were screened for antibacterial activity. A peptide isolated from the most active fraction was characterized for primary structure and evaluated for antibacterial activity, cytotoxicity to murine melanoma cells (B16-F10), and hemolytic activity. The RP-HPLC profile displayed 26 fractions, with fraction 25 being the most active. One of the two peptides present in this fraction had the primary structure determined, belonging to the group of ocellatins. Since it was not identical to other ocellatins previously reported, it was named ocellatin-VT. This peptide especially inhibited Gram-negative bacteria growth, with the highest activity against Acinetobacter baumannii and Escherichia coli (growth inhibition was higher than 95% at 8 and 16 µM, respectively). Ocellatin-VT was weakly cytotoxic to B16-F10 cells and showed low hemolytic activity. In conclusion, a new ocellatin was isolated from L. vastus skin secretion that was active against non-resistant and multidrug-resistant bacteria. Full article
(This article belongs to the Section Biological and Natural Products)
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10 pages, 1558 KiB  
Article
NEXAFS and XPS Studies of Co Doped Bismuth Magnesium Tantalate Pyrochlores
by Nadezhda A. Zhuk, Boris A. Makeev, Aleksandra V. Koroleva, Sergey V. Nekipelov and Olga V. Petrova
Chemistry 2024, 6(2), 323-332; https://0-doi-org.brum.beds.ac.uk/10.3390/chemistry6020018 - 3 Apr 2024
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Abstract
Co doped bismuth magnesium tantalate with a pyrochlore structure (sp. gr. Fd-3m) was synthesized for the first time using the standard ceramic method. Single phase Bi2Mg1−xCoxTa2O9 samples were found to be formed when x [...] Read more.
Co doped bismuth magnesium tantalate with a pyrochlore structure (sp. gr. Fd-3m) was synthesized for the first time using the standard ceramic method. Single phase Bi2Mg1−xCoxTa2O9 samples were found to be formed when x < 0.7 in the X-ray phase analysis. However, with a higher cobalt content in the samples, the impurity phase β-BiTaO4 (sp. gr. P-1) is detected, and its amount is proportional to the degree of cobalt doping. The formation of solid solutions is evidenced by a uniform increase in the unit cell parameter of the Co,Mg co doped bismuth tantalate phase with an increase in the content of cobalt ions in the samples from 10.5412(8) (x = 0.3) to 10.5499(8) Å (x = 0.7). The samples exhibit a porous microstructure consisting of chaotically oriented and partially fused elongated grains measuring 1–2 μm. The dependence of the ceramic grain size on the n(Mg)/n(Co) ratio was not determined. X-ray spectroscopy (ear dge X-ray bsorption ine tructure (NEXAFS) and X-ray photoelectron spectroscopy (XPS)) was used to study the charge state of ions in Bi2Mg1−xCoxTa2O9. The NEXAFS and XPS data showed that doping with cobalt and magnesium did not change the bismuth and tantalum oxidation states in pyrochlore; in particular, the ions maintained their oxidation states of Bi(+3), Mg(+2) and Ta(+5). The energy position of the peaks of the Ta4f-, Ta5p-, Ta4d spectra had a characteristic shift towards lower energies compared to the binding energy in pentavalent tantalum oxide Ta2O5. A shift towards lower energies is characteristic of a decrease in the effective positive charge; in particular, for the Ta4f and Ta4d spectra we presented, this energy shift was ΔE = 0.65 eV, and in the region of the Ta4d edge—0.55 eV. This in turn allowed for us to assume that tantalum atoms have the same effective charge +(5-δ). The oxidation state of cobalt ions was predominantly 2+ and partially 3+, according to NEXAFS spectroscopy data. Full article
(This article belongs to the Section Inorganic and Solid State Chemistry)
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11 pages, 4082 KiB  
Communication
In-Site Growth of Efficient NiFeOOH/NiFe-LDH Electrodes: A Streamlined One-Step Methodology
by Jing Ning, Li Xu, Wei Xu, Guizhen Li and Wen Zhang
Chemistry 2024, 6(2), 312-322; https://0-doi-org.brum.beds.ac.uk/10.3390/chemistry6020017 - 31 Mar 2024
Viewed by 710
Abstract
Oxygen evolution reactions (OER) are often the decisive step in determining the water electrolysis rate. The first row of transition metals and their derivatives, represented by Ni and Fe, have attracted much attention due to their excellent OER performance. Here, we develop a [...] Read more.
Oxygen evolution reactions (OER) are often the decisive step in determining the water electrolysis rate. The first row of transition metals and their derivatives, represented by Ni and Fe, have attracted much attention due to their excellent OER performance. Here, we develop a one-step strategy for preparing oxygen-evolving electrodes, in which the NiFeOOH-modified NiFe layered double hydroxide (NiFe-LDH) nanosheet is supported by nickel foam. At 100 mA·cm−2, the overpotential of NiFeOOH-NiFe-LDH was just 227 mV, and the duration times were over 200 h in 1 mol·L−1 KOH. Furthermore, the co-existence of LDH and hydroxyl oxides helps the oxygen evolution reaction. These results suggest the potential for this synthesis strategy to provide a low-cost, highly active OER electrocatalyst for industrial water splitting. Full article
(This article belongs to the Section Electrochemistry and Photoredox Processes)
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13 pages, 1613 KiB  
Article
Hydrophobin-Coated Perfluorocarbon Microbubbles with Strong Non-Linear Acoustic Response
by Valentina Dichiarante, Giuseppina Salzano, Philippe Bussat, Emmanuel Gaud, Samir Cherkaoui and Pierangelo Metrangolo
Chemistry 2024, 6(2), 299-311; https://0-doi-org.brum.beds.ac.uk/10.3390/chemistry6020016 - 26 Mar 2024
Viewed by 911
Abstract
Gas-filled microbubbles are well-established contrast agents for ultrasound imaging and widely studied as delivery systems for theranostics. Herein, we have demonstrated the promising potential of the hydrophobin HFBII—a fungal amphiphilic protein—in stabilizing microbubbles with various fluorinated core gases. A thorough screening of several [...] Read more.
Gas-filled microbubbles are well-established contrast agents for ultrasound imaging and widely studied as delivery systems for theranostics. Herein, we have demonstrated the promising potential of the hydrophobin HFBII—a fungal amphiphilic protein—in stabilizing microbubbles with various fluorinated core gases. A thorough screening of several experimental parameters was performed to find the optimized conditions regarding the preparation technique, type of core gas, HFBII initial concentration, and protein dissolution procedure. The best results were obtained by combining perfluorobutane (C4F10) gas with 1 mg/mL of aqueous HFBII, which afforded a total bubble concentration higher than 109 bubbles/mL, with long-term stability in solution (at least 3 h). Acoustic characterization of such microbubbles in the typical ultrasound frequency range used for diagnostic imaging showed the lower pressure resistance of HFBII microbubbles, if compared to conventional ones stabilized by phospholipid shells, but, at the same time, revealed strong non-linear behavior, with a significant harmonic response already at low acoustic pressures. These findings suggest the possibility of further improving the performance of HFBII-coated perfluorinated gas microbubbles, for instance by mixing the protein with other stabilizing agents, e.g., phospholipids, in order to tune the viscoelastic properties of the outer shell. Full article
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16 pages, 2890 KiB  
Article
Breathable Iron-Based MIL-88 Framework as Dye Adsorbent in Aqueous Solution
by Dita A. Nurani, Nabila Anisa, Irena Khatrin, Yasmine, Grandprix T. M. Kadja and Yuni K. Krisnandi
Chemistry 2024, 6(2), 283-298; https://0-doi-org.brum.beds.ac.uk/10.3390/chemistry6020015 - 14 Mar 2024
Viewed by 1603
Abstract
Metal–organic frameworks (MOFs) have been observed to exclusively eliminate dyes confined within their respective pores. In this investigation, the synthesis of a breathable MOF structure, MIL-88B(Fe), was pursued with the objective of circumventing restrictions on pore size to enhance its adsorption capabilities. The [...] Read more.
Metal–organic frameworks (MOFs) have been observed to exclusively eliminate dyes confined within their respective pores. In this investigation, the synthesis of a breathable MOF structure, MIL-88B(Fe), was pursued with the objective of circumventing restrictions on pore size to enhance its adsorption capabilities. The synthesis of MIL-88B(Fe) was carried out via the assisted solvothermal method at 373 K using inexpensive yet environmentally benign FeCl3·6H2O, 1,4-benzenedicarboxylic acid, and DMF as a metal precursor, linker, and solvent, respectively. Furthermore, the MOF was subjected to extensive analytical characterisation using XRD, FT-IR spectroscopy, N2 gas sorption, TGA, and SEM. The experimental data showed that the utilisation of MIL-88B(Fe) with a dose level of 5 mg for 180 min at a pH of 9 led to the highest levels of adsorption for both dyes, with 162.82 mg g−1 for methylene blue (MB) and 144.65 mg g−1 for rhodamine B (RhB), as a result of the contrast in the molecular size between each dye. The Langmuir and Freundlich models demonstrated a correlation with isotherms, while the thermodynamic analysis demonstrated that MIL-88B(Fe) exhibits distinct endothermic and breathable properties. The efficacy of MIL-88B(Fe) adsorbent for MB and RhB in aqueous solutions indicated exceptional performance, stability, and noteworthy reusability performance. Full article
(This article belongs to the Special Issue Low-Cost Water Treatment - New Materials and New Approaches)
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11 pages, 2248 KiB  
Article
Development and Validation of a Chromatographic Method for Ibrutinib Determination in Human and Porcine Skin
by Lucas F. F. Albuquerque, Maria Victoria Souto, Felipe Saldanha-Araujo, Juliana Lott Carvalho, Tais Gratieri, Marcilio Cunha-Filho and Guilherme M. Gelfuso
Chemistry 2024, 6(2), 272-282; https://0-doi-org.brum.beds.ac.uk/10.3390/chemistry6020014 - 27 Feb 2024
Cited by 1 | Viewed by 1251
Abstract
Ibrutinib (IBR) is a tyrosine kinase inhibitor investigated for treating solid and non-solid tumors. Considering the advantages that a topical application of IBR could generate in terms of dose reduction and side effects in skin cancer treatment, this paper presents a simple and [...] Read more.
Ibrutinib (IBR) is a tyrosine kinase inhibitor investigated for treating solid and non-solid tumors. Considering the advantages that a topical application of IBR could generate in terms of dose reduction and side effects in skin cancer treatment, this paper presents a simple and selective HPLC method for determining IBR concentration in in vitro skin permeation studies to support the development of topical formulations. The method uses a reversed-phase C18 column and a mobile phase composed of acetonitrile and 0.01 mol/L phosphoric acid at pH 3.5 (35:65 v/v), flowing at 1.0 mL/min. The oven temperature was set at 35 °C, the injection volume was 20 μL, and UV drug detection was performed at 259 nm. The validation procedure certified that this method was selective for IBR determination even when extracted from human or porcine skin matrices. The method was linear over a range of 0.2 to 15.0 μg/mL, precise, robust, and accurate, with recovery rates from the skin layers higher than 89.5 ± 5.9% for the porcine skin and higher than 92.0 ± 0.2% for the human skin. The limits of detection and quantification were 0.01 and 0.02 μg/mL, respectively. The method showed, therefore, to be adequate for use in further skin permeation studies employing IBR topical formulations. Full article
(This article belongs to the Section Medicinal Chemistry)
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8 pages, 522 KiB  
Article
Chemical Composition of the Essential Oils from Goniothalamus tortilipetalus M.R.Hend. and Their Antioxidant and Antibacterial Activities
by Aknarin Anatachodwanit, Phunrawie Promnart, Suwanna Deachathai, Tharakorn Maneerat, Rawiwan Charoensup, Thidarat Duangyod and Surat Laphookhieo
Chemistry 2024, 6(2), 264-271; https://0-doi-org.brum.beds.ac.uk/10.3390/chemistry6020013 - 23 Feb 2024
Viewed by 1255
Abstract
This work was the first investigation of the essential oil composition of Goniothalamus tortilipetalus M.R.Hend. The aim of this study is to investigate the essential oil composition extracted from different parts of Goniothalamus tortilipetalus M.R.Hend., including flowers, leaves, and twigs, and to evaluate [...] Read more.
This work was the first investigation of the essential oil composition of Goniothalamus tortilipetalus M.R.Hend. The aim of this study is to investigate the essential oil composition extracted from different parts of Goniothalamus tortilipetalus M.R.Hend., including flowers, leaves, and twigs, and to evaluate their antioxidant and antibacterial activities. The Clevenger apparatus was used for hydrodistillation to prepare the essential oils. The essential oils were investigated using gas chromatography–mass spectrometry (GC-MS). The three major compounds of the flowers were bicyclogermacrene (15.81%), selin-11-en-4-α-ol (14.68%), and E-caryophyllene (7.02%), whereas the leaves were p-cymene (39.57%), ascaridole (9.39%), and α-copaene (9.12%). In the case of the twigs, α-copaene (10.34%), selin-11-en-4-α-ol (8.85%), and p-cymene (7.76%) were the major compounds. The flower essential oil showed antioxidant activities with IC50 values of 725.21 µg/mL and 123.06 µg/mL for DPPH and ABTS assays, respectively. The flower essential oil also displayed antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus, Salmonella typhimurium, and Shigella flexneri, with the same MIC value of 640 µg/mL. Full article
(This article belongs to the Section Biological and Natural Products)
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