Molecules

Editorial

3 pages, 182 KiB

Open AccessEditorial

Special Issue “Chemical Speciation of Organic and Inorganic Components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration”

by Francesco Crea and Alberto Pettignano

Molecules 2020, 25(4), 826; https://doi.org/10.3390/molecules25040826 - 13 Feb 2020

Cited by 2 | Viewed by 1719

Abstract

Several different definitions were in the past proposed to describe the term chemical speciation, and some of them were accepted from the scientific community [...] Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

Research

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26 pages, 3233 KiB

Open AccessFeature PaperArticle

Understanding the Solution Behavior of Epinephrine in the Presence of Toxic Cations: A Thermodynamic Investigation in Different Experimental Conditions

by Francesco Crea, Concetta De Stefano, Anna Irto, Gabriele Lando, Stefano Materazzi, Demetrio Milea, Alberto Pettignano and Silvio Sammartano

Molecules 2020, 25(3), 511; https://doi.org/10.3390/molecules25030511 - 24 Jan 2020

Cited by 17 | Viewed by 4989

Abstract

The interactions of epinephrine ((R)-(−)-3,4-dihydroxy-α-(methylaminomethyl)benzyl alcohol; Eph⁻) with different toxic cations (methylmercury(II): CH₃Hg⁺; dimethyltin(IV): (CH₃)₂Sn²⁺; dioxouranium(VI): UO₂²⁺) were studied in NaCl_aq at different ionic strengths [...] Read more.

The interactions of epinephrine ((R)-(−)-3,4-dihydroxy-α-(methylaminomethyl)benzyl alcohol; Eph⁻) with different toxic cations (methylmercury(II): CH₃Hg⁺; dimethyltin(IV): (CH₃)₂Sn²⁺; dioxouranium(VI): UO₂²⁺) were studied in NaCl_aq at different ionic strengths and at T = 298.15 K (T = 310.15 K for (CH₃)₂Sn²⁺). The enthalpy changes for the protonation of epinephrine and its complex formation with UO₂²⁺ were also determined using isoperibolic titration calorimetry: ΔH_HL = −39 ± 1 kJ mol⁻¹, ΔH_H2L = −67 ± 1 kJ mol⁻¹ (overall reaction), ΔH_ML = −26 ± 4 kJ mol⁻¹, and ΔH_M2L2(OH)2 = 39 ± 2 kJ mol⁻¹. The results were that UO₂²⁺ complexation by Eph⁻ was an entropy-driven process. The dependence on the ionic strength of protonation and the complex formation constants was modeled using the extended Debye–Hückel, specific ion interaction theory (SIT), and Pitzer approaches. The sequestering ability of adrenaline toward the investigated cations was evaluated using the calculation of pL_0.5 parameters. The sequestering ability trend resulted in the following: UO₂²⁺ >> (CH₃)₂Sn²⁺ > CH₃Hg⁺. For example, at I = 0.15 mol dm⁻³ and pH = 7.4 (pH = 9.5 for CH₃Hg⁺), pL_0.5 = 7.68, 5.64, and 2.40 for UO₂²⁺, (CH₃)₂Sn²⁺, and CH₃Hg⁺, respectively. Here, the pH is with respect to ionic strength in terms of sequestration. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

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29 pages, 3165 KiB

Open AccessArticle

Speciation Studies of Bifunctional 3-Hydroxy-4-Pyridinone Ligands in the Presence of Zn²⁺ at Different Ionic Strengths and Temperatures

by Anna Irto, Paola Cardiano, Salvatore Cataldo, Karam Chand, Rosalia Maria Cigala, Francesco Crea, Concetta De Stefano, Giuseppe Gattuso, Nicola Muratore, Alberto Pettignano, Silvio Sammartano and M. Amélia Santos

Molecules 2019, 24(22), 4084; https://doi.org/10.3390/molecules24224084 - 12 Nov 2019

Cited by 13 | Viewed by 3816

Abstract

The acid–base properties of two bifunctional 3-hydroxy-4-pyridinone ligands and their chelating capacity towards Zn²⁺, an essential bio-metal cation, were investigated in NaCl aqueous solutions by potentiometric, UV-Vis spectrophotometric, and ¹H NMR spectroscopic titrations, carried out at 0.15 ≤ I/mol [...] Read more.

The acid–base properties of two bifunctional 3-hydroxy-4-pyridinone ligands and their chelating capacity towards Zn²⁺, an essential bio-metal cation, were investigated in NaCl aqueous solutions by potentiometric, UV-Vis spectrophotometric, and ¹H NMR spectroscopic titrations, carried out at 0.15 ≤ I/mol ⁻¹ ≤ 1.00 and 288.15 ≤ T/K ≤ 310.15. A study at I = 0.15 mol L⁻¹ and T = 298.15 K was also performed for other three Zn²⁺/L^z− systems, with ligands belonging to the same family of compounds. The processing of experimental data allowed the determination of protonation and stability constants, which showed accordance with the data obtained from the different analytical techniques used, and with those reported in the literature for the same class of compounds. ESI-MS spectrometric measurements provided support for the formation of the different Zn²⁺/ligand species, while computational molecular simulations allowed information to be gained on the metal–ligand coordination. The dependence on ionic strength and the temperature of equilibrium constants were investigated by means of the extended Debye–Hückel model, the classical specific ion interaction theory, and the van’t Hoff equations, respectively. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

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25 pages, 4772 KiB

Open AccessArticle

Trends and Exceptions in the Interaction of Hydroxamic Acid Derivatives of Common Di- and Tripeptides with Some 3d and 4d Metal Ions in Aqueous Solution

by András Ozsváth, Linda Bíró, Eszter Márta Nagy, Péter Buglyó, Daniele Sanna and Etelka Farkas

Molecules 2019, 24(21), 3941; https://doi.org/10.3390/molecules24213941 - 31 Oct 2019

Cited by 6 | Viewed by 3159

Abstract

By using various techniques (pH-potentiometry, UV-Visible spectrophotometry, ¹H and ¹⁷O-NMR, EPR, ESI-MS), first time in the literature, solution equilibrium study has been performed on complexes of dipeptide and tripeptide hydroxamic acids—AlaAlaNHOH, AlaAlaN(Me)OH, AlaGlyGlyNHOH, and AlaGlyGlyN(Me)OH—with 4d metals: the essential Mo(VI) and [...] Read more.

By using various techniques (pH-potentiometry, UV-Visible spectrophotometry, ¹H and ¹⁷O-NMR, EPR, ESI-MS), first time in the literature, solution equilibrium study has been performed on complexes of dipeptide and tripeptide hydroxamic acids—AlaAlaNHOH, AlaAlaN(Me)OH, AlaGlyGlyNHOH, and AlaGlyGlyN(Me)OH—with 4d metals: the essential Mo(VI) and two half-sandwich type cations, [(η⁶-p-cym)Ru(H₂O)₃]²⁺ as well as [(η⁵-Cp*)Rh(H₂O)₃]²⁺, the latter two having potential importance in cancer therapy. The tripeptide derivatives have also been studied with some biologically important 3d metals, such as Fe(III), Ni(II), Cu(II), and Zn(II), in order to compare these new results with the corresponding previously obtained ones on dipeptide hydroxamic acids. Based on the outcomes, the effects of the type of metal ions, the coordination number, the number and types of donor atoms, and their relative positions to each other on the complexation have been evaluated in the present work. We hope that these collected results might be used when a new peptide-based hydroxamic acid molecule is planned with some purpose, e.g. to develop a potential metalloenzyme inhibitor. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

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9 pages, 1017 KiB

Open AccessArticle

Modeling Solid State Stability for Speciation: A Ten-Year Long Study

by Roberta Risoluti, Giuseppina Gullifa, Elena Carcassi, Francesca Buiarelli, Li W. Wo and Stefano Materazzi

Molecules 2019, 24(16), 3013; https://doi.org/10.3390/molecules24163013 - 20 Aug 2019

Cited by 3 | Viewed by 2498

Abstract

Speciation studies are based on fundamental models that relate the properties of biomimetic coordination compounds to the stability of the complexes. In addition to the classic approach based on solution studies, solid state properties have been recently proposed as supporting tools to understand [...] Read more.

Speciation studies are based on fundamental models that relate the properties of biomimetic coordination compounds to the stability of the complexes. In addition to the classic approach based on solution studies, solid state properties have been recently proposed as supporting tools to understand the bioavailability of the involved metal. A ten-year long systematic study of several different complexes of imidazole substituted ligands with transition metal ions led our group to the definition of a model based on experimental evidences. This model revealed to be a useful tool to predict the stability of such coordination complexes and is based on the induced behavior under thermal stress. Several different solid state complexes were characterized by Thermally Induced Evolved Gas Analysis by Mass Spectrometry (TI-EGA-MS). This hyphenated technique provides fundamental information to determine the solid state properties and to create a model that relates stability to coordination. In this research, the model resulting from our ten-year long systematic study of complexes of transition metal ions with imidazole substituted ligands is described. In view of a systematic addition of information, new complexes of Cu(II), Zn(II), or Cd(II) with 2-propyl-4,5-imidazoledicarboxylic acid were precipitated, characterized, and studied by means of Thermally Induced Evolved Gas Analysis performed by mass spectrometry (TI-EGA-MS). The hyphenated approach was applied to enrich the information related to thermally induced steps, to confirm the supposed decomposition mechanism, and to determine the thermal stability of the studied complexes. Results, again, allowed supporting the theory that only two main characteristic and common thermally induced decomposition behaviors join the imidazole substituted complexes studied by our group. These two behaviors could be considered as typical trends and the model allowed to predict coordination behavior and to provide speciation information. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

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11 pages, 1633 KiB

Open AccessArticle

Associated Effects of Cadmium and Copper Alter the Heavy Metals Uptake by Melissa Officinalis

by Dorota Adamczyk-Szabela, Katarzyna Lisowska, Zdzisława Romanowska-Duda and Wojciech M. Wolf

Molecules 2019, 24(13), 2458; https://doi.org/10.3390/molecules24132458 - 4 Jul 2019

Cited by 8 | Viewed by 4103

Abstract

Lemon balm (Melissa officinalis) is a popular herb widely used in medicine. It is often cultivated in soils with substantial heavy metal content. Here we investigate the associated effects of cadmium and copper on the plant growth parameters augmented by the [...] Read more.

Lemon balm (Melissa officinalis) is a popular herb widely used in medicine. It is often cultivated in soils with substantial heavy metal content. Here we investigate the associated effects of cadmium and copper on the plant growth parameters augmented by the manganese, zinc, and lead uptake indicators. The concentration of all elements in soil and plants was determined by the HR-CS FAAS with the ContrAA 300 Analytik Jena spectrometer. Bioavailable and total forms calculated for all examined metals were augmented by the soil analyses. The index of chlorophyll content in leaves, the activity of net photosynthesis, stomatal conductance, transpiration rate, and intercellular concentration of CO₂ were also investigated. Either Cd or Cu acting alone at high concentrations in soil are toxic to plants as indicated by chlorophyll indices and gas exchange parameters. Surprisingly, this effect was not observed when both metals were administered together. The sole cadmium or copper supplementations hampered the plant’s growth, lowered the leaf area, and altered the plant’s stem elongation. Analysis of variance showed that cadmium and copper treatments of lemon balm significantly influenced manganese, lead, and zinc concentration in roots and above ground parts. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

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12 pages, 256 KiB

Open AccessArticle

Increased Aluminum Content in Certain Brain Structures is Correlated with Higher Silicon Concentration in Alcoholic Use Disorder

by Cezary Grochowski, Eliza Blicharska, Jacek Bogucki, Jędrzej Proch, Aleksandra Mierzwińska, Jacek Baj, Jakub Litak, Arkadiusz Podkowiński, Jolanta Flieger, Grzegorz Teresiński, Ryszard Maciejewski, Przemysław Niedzielski and Piotr Rzymski

Molecules 2019, 24(9), 1721; https://doi.org/10.3390/molecules24091721 - 3 May 2019

Cited by 26 | Viewed by 3903

Abstract

Introduction: Alcohol overuse may be related to increased aluminum (Al) exposure, the brain accumulation of which contributes to dementia. However, some reports indicate that silicon (Si) may have a protective role over Al-induced toxicity. Still, no study has ever explored the brain content [...] Read more.

Introduction: Alcohol overuse may be related to increased aluminum (Al) exposure, the brain accumulation of which contributes to dementia. However, some reports indicate that silicon (Si) may have a protective role over Al-induced toxicity. Still, no study has ever explored the brain content of Al and Si in alcoholic use disorder (AUD). Materials and methods: To fill this gap, the present study employed inductively coupled plasma optical emission spectrometry to investigate levels of Al and Si in 10 brain regions and in the liver of AUD patients (n = 31) and control (n = 32) post-mortem. Results: Al content was detected only in AUD patients at mean ± SD total brain content of 1.59 ± 1.19 mg/kg, with the highest levels in the thalamus (4.05 ± 12.7 mg/kg, FTH), inferior longitudinal fasciculus (3.48 ± 9.67 mg/kg, ILF), insula (2.41 ± 4.10 mg/kg) and superior longitudinal fasciculus (1.08 ± 2.30 mg/kg). Si content displayed no difference between AUD and control, except for FTH. Positive inter-region correlations between the content of both elements were identified in the cingulate cortex, hippocampus, and ILF. Conclusions: The findings of this study suggest that AUD patients may potentially be prone to Al-induced neurodegeneration in their brain—although this hypothesis requires further exploration. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

17 pages, 1796 KiB

Open AccessArticle

Analysis of Hazardous Elements in Children Toys: Multi-Elemental Determination by Chromatography and Spectrometry Methods

by Katarzyna Karaś and Marcin Frankowski

Molecules 2018, 23(11), 3017; https://doi.org/10.3390/molecules23113017 - 19 Nov 2018

Cited by 16 | Viewed by 5226

Abstract

This paper presents the results of determination of hazardous metal (Cd, Cu, Cr, Hg, Mn, Ni, Pb, Zn) and metalloid (As, Sb) levels in toys available in the Polish market. Two independent sample preparation methods were used to determine the concentration and content [...] Read more.

This paper presents the results of determination of hazardous metal (Cd, Cu, Cr, Hg, Mn, Ni, Pb, Zn) and metalloid (As, Sb) levels in toys available in the Polish market. Two independent sample preparation methods were used to determine the concentration and content of the metals and metalloids. The first one is defined by the guidelines of the EN-71 standard and undertook extraction in 0.07 mol/L HCl. This method was used to conduct speciation analysis of Cr(III) and Cr(VI), as well as for the determination of selected metals and metalloids. The second method conducted mineralization in a HNO₃ and H₂O₂ mixture using microwave energy to determine the content of metals and metalloids. Determination of chromium forms was made using the high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method, while those of metals and metalloids were made using the ICP-MS technique. Additionally, in order to determine total content of chromium in toys, an energy dispersive X-ray fluorescence spectrometer (EDX) was used. The results of the analyses showed that Cr(VI) was not detected in the toys. In general, the content of heavy metals and metalloids in the studied samples was below the migration limit set by the norm EN-71. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

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12 pages, 1842 KiB

Open AccessArticle

Evaluation of Highly Detectable Pesticides Sprayed in Brassica napus L.: Degradation Behavior and Risk Assessment for Honeybees

by Zhou Tong, Jinsheng Duan, Yancan Wu, Qiongqiong Liu, Qibao He, Yanhong Shi, Linsheng Yu and Haiqun Cao

Molecules 2018, 23(10), 2482; https://doi.org/10.3390/molecules23102482 - 27 Sep 2018

Cited by 11 | Viewed by 3443

Abstract

Honeybees are major pollinators of agricultural crops and many other plants in natural ecosystems alike. In recent years, managed honeybee colonies have decreased rapidly. The application of pesticides is hypothesized to be an important route leading to colony loss. Herein, a quick, easy, [...] Read more.

Honeybees are major pollinators of agricultural crops and many other plants in natural ecosystems alike. In recent years, managed honeybee colonies have decreased rapidly. The application of pesticides is hypothesized to be an important route leading to colony loss. Herein, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was used to determine eight highly detectable pesticides (carbendazim, prochloraz, pyrimethanil, fenpropathrin, chlorpyrifos, imidacloprid, thiamethoxam, and acetamiprid) in rape flowers. A field experiment was conducted at the recommended dose to evaluate the contact exposure risk posed to honeybees for 0–14 days after treatment. The initial residue deposits of neonicotinoids and fungicides among these compounds were 0.4–1.3 mg/kg and 11.7–32.3 mg/kg, respectively, and 6.4 mg/kg for fenpropathrin and 4.2 mg/kg for chlorpyrifos. The risk was quantified using the flower hazard quotient (FHQ) value. According to the data, we considered imidacloprid, thiamethoxam, chlorpyrifos, fenpropathrin, and prochloraz to pose an unacceptable risk to honeybees after spraying in fields, while fungicides (carbendazim and pyrimethanil) and acetamiprid posed moderate or acceptable risks to honeybees. Therefore, acetamiprid can be used instead of imidacloprid and thiamethoxam to protect rape from some insects in agriculture, and the application of prochloraz should be reduced. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

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Review

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20 pages, 2412 KiB

Open AccessReview

Zn²⁺ Interaction with Amyloid-B: Affinity and Speciation

by Giuseppe Arena and Enrico Rizzarelli

Molecules 2019, 24(15), 2796; https://doi.org/10.3390/molecules24152796 - 31 Jul 2019

Cited by 15 | Viewed by 3212

Abstract

Conflicting values, obtained by different techniques and often under different experimental conditions have been reported on the affinity of Zn²⁺ for amyloid-β, that is recognized as the major interaction responsible for Alzheimer’s disease. Here, we compare the approaches employed so far, i.e., [...] Read more.

Conflicting values, obtained by different techniques and often under different experimental conditions have been reported on the affinity of Zn²⁺ for amyloid-β, that is recognized as the major interaction responsible for Alzheimer’s disease. Here, we compare the approaches employed so far, i.e., the evaluation of K_d and the determination of the stability constants to quantitatively express the affinity of Zn²⁺ for the amyloid-β peptide, evidencing the pros and cons of the two approaches. We also comment on the different techniques and conditions employed that may lead to divergent data. Through the analysis of the species distribution obtained for two selected examples, we show the implications that the speciation, based on stoichiometric constants rather than on K_d, may have on data interpretation. The paper also demonstrates that the problem is further complicated by the occurrence of multiple equilibria over a relatively narrow pH range. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

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14 pages, 252 KiB

Open AccessReview

Serum iron, Magnesium, Copper, and Manganese Levels in Alcoholism: A Systematic Review

by Cezary Grochowski, Eliza Blicharska, Jacek Baj, Aleksandra Mierzwińska, Karolina Brzozowska, Alicja Forma and Ryszard Maciejewski

Molecules 2019, 24(7), 1361; https://doi.org/10.3390/molecules24071361 - 7 Apr 2019

Cited by 60 | Viewed by 9722

Abstract

The aim of this paper was to review recent literature (from 2000 onwards) and summarize the newest findings on fluctuations in the concentration of some essential macro- and microelements in those patients with a history of chronic alcohol abuse. The focus was mainly [...] Read more.

The aim of this paper was to review recent literature (from 2000 onwards) and summarize the newest findings on fluctuations in the concentration of some essential macro- and microelements in those patients with a history of chronic alcohol abuse. The focus was mainly on four elements which the authors found of particular interest: Iron, magnesium, copper, and manganese. After independently reviewing over 50 articles, the results were consistent with regard to iron and magnesium. On the other hand, data were limited, and in some cases contradictory, as far as copper and manganese were concerned. Iron overload and magnesium deficiency are two common results of an excessive and prolonged consumption of alcohol. An increase in the levels of iron can be seen both in the serum and within the cells, hepatocytes in particular. This is due to a number of factors: Increased ferritin levels, lower hepcidin levels, as well as some fluctuations in the concentration of the TfR receptor for transferrin, among others. Hypomagnesemia is universally observed among those suffering from alcoholism. Again, the causes for this are numerous and include malnutrition, drug abuse, respiratory alkalosis, and gastrointestinal problems, apart from the direct influence of excessive alcohol intake. Unfortunately, studies regarding the levels of both copper and manganese in the case of (alcoholic) liver disease are scarce and often contradictory. Still, the authors have attempted to summarize and give a thorough insight into the literature available, bearing in mind the difficulties involved in the studies. Frequent comorbidities and mutual relationships between the elements in question are just some of the complications in the study of this topic. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

23 pages, 1711 KiB

Open AccessReview

Speciation Analysis of Trace Arsenic, Mercury, Selenium and Antimony in Environmental and Biological Samples Based on Hyphenated Techniques

by Xiaoping Yu, Chenglong Liu, Yafei Guo and Tianlong Deng

Molecules 2019, 24(5), 926; https://doi.org/10.3390/molecules24050926 - 7 Mar 2019

Cited by 46 | Viewed by 6362

Abstract

In order to obtain a well understanding of the toxicity and ecological effects of trace elements in the environment, it is necessary to determine not only the total amount, but also their existing species. Speciation analysis has become increasingly important in making risk [...] Read more.

In order to obtain a well understanding of the toxicity and ecological effects of trace elements in the environment, it is necessary to determine not only the total amount, but also their existing species. Speciation analysis has become increasingly important in making risk assessments of toxic elements since the toxicity and bioavailability strongly depend on their chemical forms. Effective separation of different species in combination with highly sensitive detectors to quantify these particular species is indispensable to meet this requirement. In this paper, we present the recent progresses on the speciation analysis of trace arsenic, mercury, selenium and antimony in environmental and biological samples with an emphasis on the separation and detection techniques, especially the recent applications of high performance liquid chromatography (HPLC) hyphenated to atomic spectrometry or mass spectrometry. Full article

(This article belongs to the Special Issue Chemical Speciation of Organic and Inorganic components of Environmental and Biological Interest in Natural Fluids: Behaviour, Interaction and Sequestration)

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