Metal Complexes Of Amino Acids Research Articles

Phenylalanine: Amino Acid Metal Non-Enzymatic Electrochemical Voltammetric Sensors

This study presents a comparative analysis of non-enzymatic electrochemical voltammetric sensors, utilizing phenylalanine amino acid metal complexes (M: Ni, Zn, and Co) Polyaniline (PANI) nanocomposites (NCs). The PANI: Zn(Phala)2 NCs-based sensor detected dopamine (DA) with a sensitivity of 101.18 μAμM−1 cm−2. The limit of detection (LOD) for the PANI: Zn(Phala)2 NCs-based sensor was calculated as 0.391 μM. This exceptional sensitivity makes the PANI: Zn(Phala)2 NCs-based sensor highly promising for potential integration into biomedical test kits. To gain deeper insights into the structural properties of the PANI NCs, scanning electron microscopy (SEM), artificial-intelligence-based SEM, and Fourier transform infrared spectroscopy (FTIR) were employed for characterization. FTIR characterization provided insights into the functional groups of the NCs. The results of this comparative investigation a significant advancement in the field of PANI-based electrochemical sensors designed for DA sensing. The PANI: Zn(Phala)2 NCs-based sensor show great promise for a range of advanced sensing applications. The Z value of the PANI: Zn(Phala)2 NCs-based sensor is the lowest among the tested materials, indicating that the conductivity of the PANI: Zn(Phala)2 layer is higher than that of other active layers. Consequently, the PANI: Zn(Phala)2 NCs-based sensor achieved higher sensitivity in DA detection.

Hydrogen bonds of a water molecule in the second coordination sphere of amino acid metal complexes: influence of amino acid types on different complex geometries

Quantum chemical calculations at the M06L-GD3/def2-TZVPP level were done to investigate hydrogen bonds between amino acid metal complexes and a free water molecule. Octahedral nickel(II) and square planar palladium(II) complexes of glycine, cysteine, phenylalanine, and serine with different charges of metal complexes (+1, 0, and −1) were investigated. The following hydrogen bonds were considered: NH/O (amino acid is a H-donor), O1/HO (coordinated O1 oxygen from amino acid is a H-acceptor), and O2/HO (non-coordinated O2 oxygen from amino acid is a H-acceptor). Amino acid type has a small influence on interaction energies, both for octahedral nickel(II) and square planar palladium(II) complexes. The influence is the largest for NH/O and the smallest for O2/HO hydrogen bonds. For NH/O interaction, palladium(II) complexes showed stronger hydrogen bonds than nickel(II), up to −11.8 kcal mol−1 for singly positively charged complexes. Nickel(II) complexes demonstrated higher O1/HO hydrogen bond strength than palladium(II) with interaction energies up to −8.9 kcal mol−1 for singly negative complexes. With up to −9.0 kcal mol−1 interaction energy for singly negative complexes, O2/HO interactions were also stronger for nickel(II) complexes than palladium(II).

Optimal density-functional theory method for zinc-amino acid complexes determined by analyzing structural and Fourier-transform infrared spectroscopy data.

Metal-amino acid complexes are important compounds for the human body. Their nutritional value and anticancer, antibacterial, and catalytic properties are the focus of several studies. Density functional theory (DFT) can be used to predict their properties by optimizing their structures and performing electron population analyses. However, conventional computational methods cannot adequately determine the parameters of polymeric metal-amino acid complexes. Therefore, intermolecular interactions of polymers must be considered to correctly predict the properties of metal-amino acid and related metal complexes. In this study, different DFT protocols were used to acquire the infrared spectra and determine interatomic distances of two zinc-amino acid complexes, Zn(Gly)2 and Zn(Met)2. The results were compared to spectroscopic and X-ray crystallographic data, revealing that the M06 and M06-L functionals and the 6-311++G(d,p) basis set produced the smallest computational errors. Our results provide a foundation for future theoretical studies on other metal-amino acid and metal-organic complexes.

Metal-amino acid complexes (Zn, Se, Cu, Fe, and Mn) enhance immune response, antioxidant capacity, liver function enzymes, and expression of cytokine genes in Nile Tilapia reared under field conditions.

In the present study, we investigated the effects of partial or total replacement of dietary inorganic trace materials (ITM) with metal-amino acid complexes (MAACs) on immune response, antioxidant capacity, cytokine genes expression, and overall health status of Nile Tilapia Oreochromis niloticus reared in in-pond hapas (mesh cages) under field conditions. All-male Nile Tilapia with an average initial weight of about 90 g fish-1 were stocked into the hapas, in quadruplicates, at a density of 60 fish per hapa (30 fish m-3 ). The fish in each hapa were acclimatized to culture conditions and test diets for 1 week. Water quality parameters, including temperature (°C), pH, dissolved oxygen (mg L-1 ), and total ammonia (mg L-1 ), were monitored regularly. The MAACs were formulated to contain the same mineral concentrations found in the inorganic premix. Metal-amino acid complexes replaced the ITM premix at 0 (control), 25, 50, 75, and 100% levels (Table 1). The diets were fed to caged Nile Tilapia twice a day, for 80 days, at a daily rate of 3% of their body weights. The fish were weighed every 10 days, and the daily rations were readjusted. At harvest, fish in each hapa were collected, counted, and weighed collectively. Five fish from each hapa were rapidly anesthetized, and used for chemical and physiological analyses, including antioxidant and immune response analyses, liver function analysis, and gene expression. The activities of lysozyme, respiratory burst (%), alternative complement (ACH50), phagocytic cells, phenoloxidase, superoxide dismutase, glutathione peroxidase, and liver function enzymes were all improved with increasing supplemental MAACs up to the 50% substitution level. The expression of cytokine genes, including interferon, tumor necrosis factor, interleukin-1, serum alkaline phosphatase, the integrated microbial genomes, chloramphenicol acetyltransferase, and transforming growth factor genes, was significantly upregulated in fish fed on MAAC-supplemented diets compared with the control group. The 50% MAAC level produced the highest upregulation of these genes, whereas gene expression decreased with increasing dietary MAAC levels to 75% and 100%. The quadratic regression analysis indicated that about 60-65% MAAC is required for maximum promotion of immunological and oxidative stress responses, gene expression, and overall health status of Nile Tilapia reared in in-pond hapas under field conditions. Replacement of the ITM premix with a MAAC premix enhanced the immune and antioxidant responses of Nile Tilapia.

Hydrogen bonds of a water molecule in the second coordination sphere of amino acid metal complexes: Influence of amino acid coordination

The hydrogen bonds of free and coordinated amino acids with water molecule were studied by analyzing data in the crystal structures from the Cambridge Structural Database (CSD) and by quantum chemical calculations. The CSD data indicate bifurcated NH/O hydrogen bonds and O1/HO hydrogen bonds of coordinated oxygen. The O/HO hydrogen bonds of free zwitterions and non-coordinated carbonyl oxygen (O2/HO) in metal complexes form primarily linear, non-bifurcated hydrogen bonds. Calculated M06L-GD3/def2-TZVPP interaction energies for free zwitterions (glycine, cysteine, phenylalanine and, serine) and water molecule are in the range from −5.1 to −9.6 kcal/mol for NH/O and from −6.9 to −7.6 kcal/mol for O/HO interactions. Coordinated amino acids in neutral octahedral cobalt(III) complexes have NH/O interaction energies ca. -7.4 kcal/mol, independent of the amino acid. The singly and doubly charged complexes have stronger NH/O interactions; the strongest has energy of −16.9 kcal/mol. In the case of O1/HO hydrogen bond, the interaction energy decreases upon coordination; interactions are quite weak for neutral complexes (−2.2 to −2.6 kcal/mol). For O2/HO hydrogen bonds, all amino acids except serine show slightly stronger interaction in singly negative complexes (−6.3 to −8.0 kcal/mol), while interactions are weaker for neutral complexes (−2.8 to −4.4 kcal/mol), comparing to zwitterions.

Synthesis, Characterization, and Antibacterial Properties of mixed ligand Complexes of (L-leucine and 8-hydroxyquinoline) with Fe (III ),Cr (III) La(III)) and Ru(III ) ions

The research includes the synthesis and identification of the mixed ligands complexes of M+3 Ions in general composition ,[M(Leu)2(Q)]
 Where L-leucin (C6H13NO2)symbolized as( Leu H) as a primary ligand and
 8-hydroxyqinoline,(C9H7NO) symbolized as (8-HQ) as a secondary ligand .
 The ligands and the metal chlorides were brought in to reaction at room temperature in ethanol as solvent. The reaction required the following molar ratio [(1:1:2)(metal): Q-:2Leu-] with M(III ) ions, were 
 M(III) = Fe (III ),Cr (III) La(III)) and Ru(III )
 The reaction gave solid crystalline complexes which have been characterized us the following techniques: Thermal stability, Solubility, Molar conductivity, Determination the percentage of the metal in the complexes by (AAS). Spectroscopic Methods [FT-IR and UV-Vis], and. The proposed structure of the complexes using program, chem. office 3D(2006) .], Biological effects for some complexes were investigated .
 Numerous papers have been published on metal complexation of amino acids and derivatives during the past ten years. Metal amino acid complexes have long been of interest as models for metal –Ligand systems and interaction which may occur in nature(1)Biological importance of several amino acids their complexes with transition metals is well documented(2-3)The amino acid L- leucin and various transition metals are important in the biological functions of humans, animals, and plants. L- leucine is one of the twenty major amino acids and is considered an essential amino acid (4)
 8-hydroxyqinoline or 8-qinolineis an organic compound with the formula C9H7NO2 is the name most commonly used ,while its trivial name is (oxine),which is conventionally used for the description of chelate compounds Oxinates ,as out of seven possible hydroxyqinoles, only 8-hydroxyqinoline forms chelate with metal ions . [5-6]
 Ruthenium polypyridyl and phenanthroline complexes have been extensively investigated because of their interesting photochemical[7],catalytic [8], biological [9] and electrochemical [10,11] properties.
 Lanthanide(III) carboxylates have been widely studied in recent years due to their physico-chemical properties, variety of structural types and potential uses as fluorescent sensors. The isomers of mono-,di- and trimethoxybenzoates of rare earth elements(III) have been examined. [12-13]
 A series of ruthenium metal complexes involving mono-sulfonylated non-innocent o-phenylenediamine ligands have been characterized in detail using NMR, MS, FT-IR, X-Ray, UV-vis and electrochemical studies. [14]
 In this paper we present the synthesis and study of Cr(III),Fe(III) La(III) and Ru(III) complexes with amino acid (L-leucin) as a primary ligand and 8-hydroxyqinoline as a secondary ligand have been used, respectively.

Metal-amino acid complexes (Zn, Se, Cu, Fe and Mn) as a replacement of inorganic trace minerals in commercial diets for Nile tilapia (Oreochromis niloticus) reared under field conditions: Effects on growth, feed efficiency, gut microbiota, intestinal histology, and economic return

An 80-day trial was carried out to evaluate the effects of replacing dietary inorganic trace minerals (ITM), with metal-amino acid complexes (MAAC) on the growth rates, feed utilization, economic return, body composition and mineralization, gut microbiota, and intestinal histology of Nile tilapia (Oreochromis niloticus) reared in in-pond hapas, under commercial conditions. The fish (93.7 g) were stocked in 2-m3 hapas, in quadruplicates, at a density of 30 fish m−3 (60 fish hapa−1). Five isonitrogenous (30% CP), isoenergetic (17 MJ kg−1) extruded (floating) commercial tilapia diets were produced, containing 0, 25%, 50%, 75% and 100% MAAC as a replacement of the commercial ITM premix. In the beginning, the diets were fed to the fish at a daily rate of 3% of their body weight (BW), but the feeding rate was reduced to 2.7% BW at the beginning of the second month. The best growth performance and feed efficiency were achieved at 50% MAAC level, with no further improvement registered above this level. Except for lipid content, tissue proximate composition was significantly affected by MAAC supplementation. Economic analysis indicated that MAAC-based diets were more profitable than the control, ITM-supplemented diet, with 50% replacement showing the highest return (21% increase) over the control diet. Tissue Fe and Mn levels did not differ, while tissue Cu was higher in fish fed ITM than in those fed MAAC diets. Tissue Zn and Se increased with increasing MAAC up to 50% and 75% replacement and decreased with further MAAC supplementation. Bone Cu and Mn were not affected by dietary mineral premix; whereas Fe, Zn and Se were significantly altered. Bone Fe concentration significantly decreased at 75% and 100% MAAC levels, whereas bone Zn increased with increasing MAAC to 50%. Bone Se was lower in fish fed ITM than in those fed MAAC at 25% replacement, however, Se was not significantly affected by further increases in MAAC concentrations. Digestive enzyme activity was improved with increasing supplemental MAAC up to 50% substitution level. Fish fed MAAC showed significantly higher abundances of intestinal beneficial bacteria (Bacillus and Lactobacillus.) and lower abundances of putative pathogenic bacteria (Staphylococcus and Streptococcus) than the control group. The length of the intestinal folds and the number of goblet cell counts also significantly increased in fish fed MAAC up to 50% inclusion. Quadratic regression analyses revealed that about 50–55% MAAC is required for optimum performance, body mineralization, intestinal absorptive capacity, and beneficial intestinal microbiota.

Exploring the Cobalt–Histidine Complex for Wide-Ranging Colorimetric O2 Detection

Developing a robust, cost-effective, and user-friendly sensor for monitoring molecular oxygen (O2) ranging from a minute to a medically relevant level (85–100%) in a stream of flowing breathable gas is vital in various industrial domains. Here, we report an innovative application of the cobalt(l-histidine)2 complex, a bioinspired model of O2-carrying metalloproteins, for rapid and reliable sensing of O2 from 0 to 100% saturation levels under realistic conditions. We have established two distinct colorimetric O2 detection techniques, which can be executed with the use of a common smartphone camera and readily available color-detecting software. A series of spectroscopic experiments were performed to demonstrate the molecular-level alteration in cobalt(l-histidine)2 following its exposure to oxygen, leading to an exclusive pink-to-brown color change. Therefore, this study establishes a template for designing bioinspired molecular complexes for O2 sensing, leading to practical and straightforward solutions. This metal-amino acid complex’s broad-spectrum sensing of O2 has widened the scope of bioinspired model complexes for divergent applications in industrial sectors.

Tin Carboxylate Complexes of Natural Bacteriochlorin for Combined Photodynamic and Chemotherapy of Cancer è.

Photodynamic therapy (PDT) is currently one of the most promising methods of cancer treatment. However, this method has some limitations, including a small depth of penetration into biological tissues, the low selectivity of accumulation, and hypoxia of the tumor tissues. These disadvantages can be overcome by combining PDT with other methods of treatment, such as radiation therapy, neutron capture therapy, chemotherapy, etc. In this work, potential drugs were obtained for the first time, the molecules of which contain both photodynamic and chemotherapeutic pharmacophores. A derivative of natural bacteriochlorophyll a with a tin IV complex, which has chemotherapeutic activity, acts as an agent for PDT. This work presents an original method for obtaining agents of combined action, the structure of which is confirmed by various physicochemical methods of analysis. The method of molecular modeling was used to investigate the binding of the proposed drugs to DNA. In vitro biological tests were carried out on several lines of tumor cells: Hela, A549, S37, MCF7, and PC-3. It was shown that the proposed conjugates of binary action for some cell lines had a dark cytotoxicity that was significantly higher (8–10 times) than the corresponding metal complexes of amino acids, which was explained by the targeted chemotherapeutic action of the tin (IV) complex due to chlorin. The greatest increase in efficiency relative to the initial dipropoxy-BPI was found for the conjugate with lysine as a chelator of the tin cation relative to cell lines, with the following results: S-37 increased 3-fold, MCF-7 3-fold, and Hela 2.4-fold. The intracellular distribution of the obtained agents was also studied by confocal microscopy and showed a diffuse granular distribution with predominant accumulation in the near nuclear region.

HEAT STRESS MANAGEMENT STRATEGIES IN POULTRY

In recent years, the problem of rising seasonal temperatures has become more acute in Ukraine. Periods of heat, when the temperature outside in summer exceeds 30 °C, and in some regions reaches 40 °C, become longer, which negatively affects the main production indicators of farms for raising animals and poultry and leads to increased deaths due to heat stress. As a result, farms suffer significant economic losses. Under conditions of high external temperature and humidity (> 30 °C,> 60 %) in the bird stress develops rapidly, the internal body temperature rises by 0.5-1.0 °C, respiration increases from 22 to 200 cycles per minute (so-called symptom of "hyperpnea") and due to the absence of sweat glands, arterial-venous anastomoses are activated in the areas of the body through which the main heat transfer is carried out: ridges, earrings, open skin of the feet.
 There are a number of effective strategies to help minimize the negative impact of high outdoor temperatures on poultry, which can be divided into technical, technological, feed and medicinal. Technical strategies include: equipping poultry houses with evaporative cooling systems and tunnel ventilation, thermal insulation of roofs and walls to help reduce the negative effects of heat stress. Technological strategies include: reducing the density of poultry, reducing the thickness of the litter, the use of intermittent light, avoidance of feeding in the hottest period of the day; regular purification and disinfection of water and irrigation systems; water acidification; increase the watering front by 20-25 %. Feeding strategy during heat stress: increasing the proportion of fat relative to carbohydrates, reducing protein and increasing the level of easily digestible amino acids, the introduction of electrolytes, increasing the dose of vitamins C and E, limiting feed intake. Increasing the proportion of microelements by introducing into the diet of highly effective metal-amino acid complexes, especially those containing zinc, manganese and selenium. To reduce the negative impact of heat stress on poultry, veterinary drugs and feed additives, both mono - and multicomponent, are used, including veterinary drugs containing acetylsalicylic, ascorbic and citric acids and feed additives containing essential oils, menthol, micro- and macro elements in the form of sulfates and sulphates and vitamins.

Study of metal-amino acid [Cr(III)-Trp]2+ complex and ninhydrin reaction: role of gemini micellar solution on rate constant

In this article, the study of metal-amino acid complex and ninhydrin reaction was examined in gemini micellar solution using a UV-visible spectrophotometric measurement. The role of varying amounts of gemini micellar systems on rate constant of the study was investigated. Initially, rate constant (k ψ) enhances, below cmc and levelling-off areas are, then, noticed up to 400 × 10−5 mol dm−3. Later, gemini offers a third region of fast enhancement k ψ above 400 × 10−5 mol dm−3. Gemini surfactant series provided more efficient implications on the study than pure water and their monomeric traditional surfactant system. The values of rate constant, k ψ, were determined under a set of different experimental reaction situations with the help of a computer-based procedure. Such unfamiliar behaviour developed by gemini micellar solutions was treated by pseudo-phase model of micellar activity. An electrical conductometric measurement was employed to measure critical micellar concentration (cmc) of pure gemini micellar solutions and mixed systems. Several activation parameters were also determined by Eyring’s equation and different constants. Data obtained confirmed that lower values of activation enthalpy (ΔH #) with large negative activation entropy (ΔS #) were attained in gemini than aqueous. A plausible reaction mechanism of the study has been discussed and proposed.

Synthesis and characterization of geminis and implications of their micellar solution on ninhydrin and metal amino acid complex.

In our study, three gemini dicationic surfactants with different methylene group spacer (16-6-16, 16-5-16 and 16-4-16) have been synthesized and characterized in solution by 1H NMR spectroscopic technique. The implications of gemini micellar solution on ninhydrin and metal amino acid complex ([Cu(II)-Trp]+) were performed by the means of single-beam UV–visible spectroscopy. The absorbance was noted at regular time intervals and values of rate constant (kψ) were determined by using a computer-based program. Synthesized surfactants proved as an efficient catalyst on the interaction of ninhydrin with metal amino acid complex as compared with conventional surfactant and aqueous systems. The required description regarding the implications of gemini dicationic surfactants are provided in the text in detail. The conductivity technique was applied in order to get critical micelle concentration (cmc) of geminis in the presence and absence of reactants. Catalytic results developed in gemini dicationic surfactant system were explained effectively by pseudo-phase model. Various thermodynamic quantities, viz., activation energy, Ea, activation enthalpy, ΔH#, and activation entropy, ΔS#, were obtained on interaction of ninhydrin with [Cu(II)-Trp]+ in gemini systems by applying Eyring equation. A detailed explanation about these evaluated parameters was also made.

Soybean protein isolate-based microgels bounding amino acid metal complexes for scavenging superoxide anion radicals

Superoxide anion radical (O 2 •− ) is a noxious reactive oxygen species (ROS). Transition metal ion complexes have been generally used as antioxidants to eliminate ROS. In this work, the soybean protein isolate (SPI), a biodegradable vegetable protein, was first combined with polyvinyl alcohol through hydrogen bonding for the synthesis of SPI-based polymer microgel (SPI-PmG) carrier. Furthermore, a kind of novel water-soluble biopolymer/metal complex conjugate (SCM@SPI-PmG) was prepared by binding the 4-hydroxy salicylaldehyde amino acid Schiff-base metal complexes (HOSalCysM, M = Cu, Zn) with the SPI-PmG. The structure, morphology and stability of SPI-PmG were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, X-ray diffraction pattern and thermogravimetric analysis. The result revealed that the diameter of the obtained SPI-PmG ranged from 150 to 400 nm. Besides, the scavenging superoxide anion free radical activity of biopolymer–metal complexes was determined by nitroblue tetrazolium light reduction assay method. Compared with the carrier SPI-PmG, the scavenging activity of the SCM@SPI-PmG was greatly improved. Remarkably, the superoxide dismutase (SOD) simulation of the SCCu@SPI-PmG reached 297.10%, and the SCZn@SPI-PmG simulation reached 35.13%. As a consequence, SCCu@SPI-PmG could be considered as a biofunctional mimic of enzyme SOD and has a promising application prospect in antioxidant drug field.

Synthesis, Characterization, and Biological Evaluation of Chromium(III) Complexes of Alanine and Valine

Two metal-amino acid complexes, Cr(III)-alanine and Cr(III)-valine, were synthesized and characterized by IR spectroscopy, powder X-ray diffraction (XRD) analysis, magnetic susceptibility, and molar conductivity measurements. Molar conductivity measurements indicated that the composition of the metal complexes corresponds to a metal-amino acid ligand ratio of 1:3. The IR spectra indicated that the amino acids act as bidentate ligands with coordination involving the carboxyl oxygen and the nitrogen of the amino group. Magnetic susceptibility measurements revealed a six-coordinate local symmetry around the Cr(III) ions which depicted that the complexes were paramagnetic with magnetic moment values ranging from 5.10 to 6.00 BM. Powder XRD studies confirmed that the amino acid complexes were crystalline with monoclinic crystal structure. The in vitro biological activity of the investigated chromium(III) complexes with alanine and valine was tested against Bacillus subtilis, Staphylococcus aureus, Salmonella typhi, Pseudomonas aeruginosa, and Escherichia coli. All the microorganisms were standardized using 0.5 McFarland standard. The antimicrobial studies showed that the ligands were biologically active with an inhibition zone range of 10-17 mm and their metal complexes showed significantly enhanced antimicrobial sensitivity with an inhibition zone range of 12-21 mm. The standard drug showed slightly better activity with an inhibition zone range of 24-38 mm.

Effect of Moisture Content on the Diverse Structure State of the Octanoyl Alanine Metal (Mg, Ca) Complexes

Octanoyl alanine ligands and metal ions (Mg2+, Ca2+) form metal complexes of octanoyl alanine through chemical coordination bonds [1]. According to the acid base reaction and the Lewis acid-base theory[2], the molecule or ion of the central atom or ion (collectively called the central atom) and the ligand (called ligand) around it, completely or partially by the coordination bond to form metal complex. These octanoyl alanine complexes are soluble in water and easily ionize into internal coordination ions and external ions, while the ligands and central atoms do not ionize in the inner boundary. The octanoyl alanine magnesium and calcium complexes belongs to the amino acid metal complexes, which can be widely used in daily life, industrial production and life science in the future application. Recently, with the rapid development of amino acid metal complexes [3-7], it is not only associated with inorganic compounds and organometallic compounds, but also overlaps with the chemistry, coordination catalysis and molecular biology of the current chemical frontiers [8-10]. In this paper, [C10H20NCO3]2M type metal complexes prepared by combining octanoyl alanine ligand with metal ions containing functional group COOH, the influence of water content on the DSC curve and surface morphology of metal complexes was studied, and the information of the diversified structure state of the materials complex can be obtained.

Synthesis, Characterization, And Antifungal Studies of Four Novel Benzilic Acid Amino Acid Metal Complexes

Synthesis, Characterization, And Antifungal Studies of Four Novel Benzilic Acid Amino Acid Metal Complexes

SYNTHESIS AND ANALYSIS OF ZINC METHIONINE, ZINC GLYCINE, COPPER LEUCINE, AND COPPER GLYCINE COMPLEXES USING ATOMIC ABSORPTION SPECTROPHOTOMETRY

Objective: The aim of this study was to perform metal-amino acid synthesis and to analyze the free and bonded mineral concentrations.Methods: In this study, the synthesis of amino acid metal complexes was carried out by reacting free metal ions, derived from a water-soluble metalsalt, with amino acids in a 1:2 molar ratio.Results: The respective yields of this synthesis process were 95.38%, 95.95%, 76.31%, and 93.91% for zinc (Zn)-methionine (Zn(Met)2), Zn-glycine(Zn(gli)2), copper-leucine (Cu(leu)2), and Cu-glycine (Cu(gli)2) complexes, respectively. The metal-amino acid complexes were then separated usingcolumn chromatography and further analyzed by atomic absorption spectrophotometry (AAS). The bonded metal concentrations of the Zn(Met)2,Zn(gli)2, Cu(leu)2, and Cu(gli)2 complexes were 189.32 mg/g, 353.78 mg/g, 180.89 mg/g, and 275.11 mg/g, respectively. The free metal concentrationsof the Zn(Met)2, Zn(gli)2, Cu(leu)2, and Cu(gli)2 complexes were 13.57 mg/g, 12.92 mg/g, 0.19 mg/g, and 2.12 mg/g, respectively.Conclusion: In this study, Zn(Met)2, Zn(gli)2, Cu(leu)2, and Cu(gli)2 complexes were successfully formed and analyzed. The mineral concentration ineach complex differed depending on the type of mineral and ligand.

The Effect of Foliar-Applied Manganese in Mineral and Complex Forms with Amino Acids on Certain Defense Mechanisms of Cucumber (Cucumis sativus L.) Against Powdery Mildew

Manganese (Mn) is an essential micronutrient with positive effects on enhancing plant tolerance against fungal diseases. On the other hand, it has been suggested that metal–amino acid complexes are more effective than mineral sources in supplying Mn and improving the translocation and distribution of these metal nutrients in plants. Meanwhile, certain amino acids, that is, lysine and methionine, play an important role in crop resistance to biotic stresses. Little information is, however, available regarding the effect of foliar-applied Mn in mineral and complex forms with amino acids on crop tolerance to powdery mildew caused by Podosphaera fuliginea. In this nutrient solution experiment, the effect of foliar-applied Mn, in the form of MnSO4, Mn-methionine (Mn-Met) and Mn-lysine (Mn-Lys), on certain defense mechanisms of cucumber (Cucumis sativus L. cv. Espadana RZ) against powdery mildew was investigated. Different Mn sources were applied as foliar spray 4 days before and 6 days after inoculation with P. fuliginea. The results revealed that Mn application prior to pathogen inoculation decreased the disease in the treated and newly growing leaves; however, the efficiency of Mn–amino acid complexes in disease suppression was greater than that of MnSO4. Post-inoculation spray of Mn had no effect on the disease reduction of the newly growing leaves, but all Mn sources diminished disease severity equally in the treated leaves. In such leaves, regardless of the application time, the higher content of cell wall lignin was found in the plants treated with MnSO4, in comparison with those treated with Mn–amino acid complexes. In the newly growing leaves, the foliar application of Mn–amino acid complexes before inoculation resulted in a significant increase of leaf cell wall lignin content, whereas MnSO4 was ineffective. Pre-inoculation spray of MnSO4 led to increasing PO and PPO activities in the treated leaves, whereas Mn–amino acid complexes had no significant effect on the activity of these enzymes in the same leaves. Application of Mn-Met and Mn-Lys after pathogen inoculation led to a significant decrease of PPO activity in the treated leaves. In general, the results of the present study revealed that the time of Mn foliar application could have a considerable effect on controlling cucumber powdery mildew. Foliar application of Mn before infection with P. fuliginea could strengthen the defensive structures of the plant and help to prevent the disease incidence.

A Metal-Amino Acid Complex-Derived Bifunctional Oxygen Electrocatalyst for Rechargeable Zinc-Air Batteries.

Bifunctional oxygen electrocatalyst: A metal-amino acid complex is developed to prepare high-performance mesoporous carbon electrocatalyst for both oxygen reduction and oxygen evolution reactions. Such prepared catalyst can be used to assemble rechargeable zinc-air batteries with excellent durability. This work represents a new route toward low-cost, highly active, and durable bifunctional electrocatalysts for cutting-edge energy conversion devices.

Thermal studies and mass loss inhibition for some new mixed amino acid metal complexes with their applications

A thermal gravimetric analysis was studied for the new metal mixed-ligand complexes of copper(II), nickel(II), cobalt(II), and zinc(II) metals formed with glutamic acid as a primary ligand and nitrilotriacetic acid (H3NTA) as a secondary ligand which have been characterized by their elemental analysis, magneto-chemical measurements, Fourier transform infrared (FTIR), UV–Vis spectrophotometer, thermal gravimetric analysis, and mass spectroscopy studies. Glutamic acid in these complexes acts as a bidentate ligand, coordinating through the one nitrogen of the amino group and one oxygen of the carboxylate group, whereas nitrilotriacetic acid shows a tridentate nature, and the coordination occurs through two carboxylate oxygen and one nitrogen of the amino group. Water molecules satisfy the remaining coordination positions. The complexes have been suggested to show geometry of an octahedral symmetry. The results were indicated that the mixed complexes were isolated in 1:1:1 molar ratio (metal–glutamic–HNTA), and the molecular structures were suggested to be [M(glutamic)(HNTA) (H2O)]·(2–1.5)H2O. The antimicrobial activities of our prepared complexes evaluated against Escherichia coli, Staphylococcus aureus, Candida albicans, and Aspergillus flavus (isolates from Micro-analytical Center, Faculty of Science, Cairo University) were investigated. Also, our prepared complexes were evaluated for their in vitro anticancer activity against hepatocellular carcinoma. In addition, the mass loss inhibition effects for copper and aluminum metal plates by our prepared complexes in 1 M HCl were studied.