Water-soluble Complexes Research Articles

A combined catalytic and kinetic study of the aqueous-biphasic hydrogenation of allylbenzenes by using a dihydride-ruthenium complex containing tri(sodium-o-sulfonatedphenylphosphine) ligands

The water-soluble complex Ru(H)2(CO)(o-TPPTS)3 was used as a catalyst precursor for the hydrogenation of naturally occurring allylbenzenes, such as eugenol, estragole, and safrole, in an aqueous biphasic system. Under the best-operating conditions, P = 900 psi (62 atm), Tθ = 90 °C (363.15 K), S/C ratio = 80/1, time = 6 h, and stirring rate = 800 rpm, this catalyst precursor showed a good activity and selectivity towards C = C bond hydrogenation. When working with eugenol, the isomerization by-product (isoeugenol) was obtained in addition to the hydrogenation product. Preliminary kinetics studies indicate that the individual reactivity order was estragole > allylbenzene > safrole > eugenol. In contrast, a quaternary olefin mixture showed that the hydrogenation rate was somewhat similar to that of individual allylbenzene. The classic Hg test confirmed the molecular nature of the Ru water-soluble complex. Finally, the catalyst recycling study indicates that this complex can be used up to three times, maintaining the same catalytic activity.

Polysaccharide content and composition analysis in the herb <i>Astragalus albicaulis</i> DC

Aim – to isolate and analyze the polysaccharides content in the herb Astragalus albicaulis.
 Material and methods. The object of the study was the herb Astragalus albicaulis harvested in the Kursk region in 2022 during the period of mass flowering. To isolate the polysaccharide complex, polyphenolic compounds were previously removed from the raw material. After drying, a water-soluble polysaccharide complex, pectin substances, hemicellulose A and hemicellulose B were sequentially isolated from the extraction cake. As extractants, purified water was used to isolate the water-soluble polysaccharide complex, a mixture of 0.5% solutions of oxalic acid and ammonium oxalate (1:1) was used for pectin substances extraction, to obtain hemicelluloses – a 10% aqueous solution of alkali followed by neutralization with acetic acid. The composition of the obtained substances was analyzed after acid hydrolysis using paper chromatography.
 Results. It was found that the yield of water-soluble polysaccharides from the herb Astragalus albicaulis was 9.41% ± 0.46%, pectin substances – 17.49% ± 0.62%, hemicellulose A – 0.86% ± 0.04%, hemicellulose B – 5.36% ± 0.25%. After acid hydrolysis, 5 monosaccharides were found in the complex of water-soluble polysaccharides: rhamnose, xylose, arabinose, galactose, and glucuronic acid, of which arabinose and galactose were predominant. The monosaccharide composition of pectin substances was represented by xylose, arabinose, glucose, galactose and galacturonic acid, galacturonic acid predominated. As a result of the identification of hydrolysis products of hemicellulose A and B, rhamnose, xylose and glucose were found, the predominant monosaccharide was xylose.
 Conclusion. For the first time, complexes of polysaccharides – water-soluble polysaccharides, pectin substances, hemicellulose A and B – were isolated and studied by fractions from the herb Astragalus albicaulis, their qualitative composition was registered. The data obtained indicates that the herb Astragalus albicaulis can be used as a source of natural polysaccharides.

A new β-cyclodextrin-based nickel as green and water-soluble supramolecular catalysts for aqueous Suzuki reaction

A water-soluble nickel complex based on amino-β-CD was developed using a facile method and exhibits excellent catalytic performance in the Suzuki reaction in water. This synthesized complex has been characterized using UV–Vis, AAS, TGA, and FT-IR techniques. The easily synthesized novel supramolecular catalysts have been applied as a green and eco-friendly catalyst in the Suzuki coupling for preparing diverse biaryls. This result indicates that using 2.5 mol% of nickel, K2CO3 as the best base, and water as the green solvent are the best reaction conditions. This new catalyst features easy handling, low-cost, mild, and simple protocol. The use of low-cost and accessibility of the reagents, modest conditions, and good yields of products are notable characteristics of this method. Using aqueous media with this catalyst as a proper catalyst makes the presented process a fascinating method compared to most reports. Under mild reaction conditions, this green Ni(II)-β-CD catalyst displayed recyclable behavior seven times with minor loss in its catalytic activity.

Structure and Physico-Mechanical Properties of Polyelectrolyte Complexes Based on Sodium Carboxymethylcellulose Polysaccharide and Polyacrylamide

In this paper, the structure and physico-mechanical properties of films of polyelectrolyte complexes (PEC) based on sodium carboxymethylcellulose (Na-CMC) with linear polyacrylamide (PAA) have been studied. Polyelectrolyte complexes were obtained by mixing aqueous solutions of Na-CMC and PAA components in various ratios of components and pH of the medium. The structure of the obtained products was determined using IR spectroscopy and electron microscopy. IR spectra in the range 400–4000 cm-1 were recorded on NIKOLET Magna-560 IR and Specord-75IR spectrophotometers (Carl Zeiss, GDR). The mechanical properties of films of polyelectrolyte complexes were determined by stretching at a constant speed of movement of the lower clamp, 50 mm/min, on an Instron-1100 automatic dynamometer (England) at room temperature. IR spectroscopic data showed that polyelectrolyte complexes based on Na-CMC and PAA were stabilized due to the cooperative ionic bond between Na-CMC carboxylate anions (-COO-) and amine groups (-NH2) of polyacrylamide. It is shown that PEC films with an equimolar ratio of Na-CMC and PAA components have an increased value of mechanical strength (σр = 38 MPa), elastic modulus (Е = 73 MPa) and a minimum relative elongation (ε = 0.5%). And in excess of Na-CMC or PAA leads to a decrease in mechanical strength and elastic modulus, which is associated with a decrease in the frequency of intermolecular bonds. It has been ascertained that water-soluble polyelectrolyte complexes based on Na-CMC and PAA with increased strength properties can be obtained from solutions of components taken at an equimolar ratio of interacting components. By changing the ratio of components, properties such as mechanical strength, modulus of elasticity and elongation can be controlled. This can serve as one of the means of controlling the structure and properties of Na-CMC and PAA polyelectrolyte complexes. The regulation of the physico-mechanical properties of PEC films opens up wide opportunities for their use as a soil structure former in agriculture and water management and as the basis for soft drugs in pharmacy.

Simultaneous adsorption of malachite green, methyl orange, and rhodamine B with TiO2/macadamia nutshells-derived activated carbon composite

Abstract In this study, TiO2/activated carbon (TiO2/MAC) composite was synthesized from activated carbon prepared from macadamia nutshells and a water-soluble titanium complex, and it was used to simultaneously adsorb malachite green (MG), methyl orange (MO), and rhodamine B (RhB) from aqueous solutions. The kinetic studies show that the pseudo-second-order kinetic model describes the adsorption experimental data the best. The equilibrium data of the trinary system were analyzed via the ideal adsorption solution theory (IAST) and the Langmuir and P-factor-Langmuir extended models that combine the three single-component isotherms (Langmuir, Freundlich, and Sips). The AICs (Akaike Information Criterion) values indicate that IAST incorporating the Langmuir model is the most suitable to describe the removal of the dyes in the trinary solution. The TiO2/MAC composite exhibits a high dye adsorption capacity compared with those of the published adsorbents. The thermodynamic analysis reveals that the adsorption is spontaneous and endothermic. The high adsorption capacity and the recyclability through photocatalytic self-cleaning show that TiO2/MAC can be utilized as a sustainable alternative for the simultaneous elimination of textile dyes from effluents.

Designing and preparing supramolecular encapsulation systems based on fraxetin and cyclodextrins for highly selective detection of nicotine

Herein, a series of water-soluble supramolecular inclusion complexes (ICs) probes were prepared using cyclodextrins (CDs) and fraxetin (FRA) to detect nicotine (NT) with high selectivity in vitro and in vivo. The FRA/CD ICs prepared through the saturated solution method exhibited excellent water solubility, stability, and biocompatibility. A clear host-guest inclusion model was provided by the theoretical calculations. The investigation revealed that NT was able to enter into the cavities of FRA/β-CD IC and FRA/γ-CD IC, and further formed charge transfer complexes with FRA in the CD cavities, resulting in a rapid and highly selective fluorescence-enhanced response with the lowest detection limits of 1.9 × 10−6 M and 9.7 × 10−7 M, and the linear response ranged from 0.02 to 0.3 mM and 0.01–0.05 mM, respectively. The IC probes showed good anti-interference performance to common interferents or different pH environments, with satisfactory reproducibility and repeatability of response to NT. Furthermore, the potentiality of the probes was confirmed through fluorescence imaging experiments using human lung cancer cells and the lung tissue of mice. This study offers a fresh perspective for detecting NT in environmental and biomedical analysis.

Improving antioxidant activities of water-soluble lignin-carbohydrate complex isolated from wheat stalk through prolonging ball-milling pretreatment and homogeneous extraction

Water-soluble lignin-carbohydrate complex (LCC) rich in polysaccharides exhibits benign in vitro antioxidant activities and distinguishes high biocompatibility from lignin-rich LCC and lignin. However, the antioxidant activity of water-soluble LCCs remains to be improved and its structure-antioxidant relationship is still uncertain. Herein, structurally diversified water-soluble LCCs were isolated under different ball-milling pretreatment durations (4, 6, 8 h), extraction pathways (homogeneous and heterogeneous), and isolation routines (water extracts and residues after water extraction). Their structures were characterized by wet chemistry, chromatography and spectroscopies. Antioxidant activities were evaluated by ferric reducing antioxidant power and 1,1-diphenyl-2-picrylhydrazyl radicals scavenging rate (RDPPH). Results show that altering ball-milling duration and isolation procedures cause varied structures and antioxidant activities of the water-soluble LCCs. Specifically, prolonging ball-milling duration to 8 hours and homogeneous extraction can enhance their antioxidant activity through releasing more phenolic structures and promoting the extraction of high-molecular-weight LCCs via reducing mass-transfer resistance, respectively. As a result, the RDPPH of water-soluble LCCs reaches up to 97.35%, which is associated with the arabinan content with statistical significance (P < 0.05). This study provides new insights into the structure-antioxidation relationship of herbaceous LCC as potential antioxidants.

Influence of the Process Parameters on the Synthesis of Urea Phosphate and the Properties of the Obtained Product

The ever-increasing food demand associated with the growing human population poses similar challenges to both farmers and fertilizer producers. In view of climate change and the increasing area of infertile land, it is very important to use correctly balanced and highly effective fertilizers in agriculture. Water-soluble fertilizers are becoming more and more popular. It is convenient to use them together with irrigation water because this reduces the negative effects of droughts and accelerates the assimilation of nutrients needed by plants. The aim of this work was to synthesize urea phosphate (UP) (water-soluble complex nitrogen–phosphorus fertilizers NPF) through the reaction of phosphoric acid and urea. The most important moment of the work is that the synthesis was carried out using a purified wet-process phosphoric acid (PWPA) and urea by varying the stoichiometric ratio and the duration time of crystallization. Based on the results of the experiment, it was found that, in the presence of excess acid, the concentration of phosphorus pentoxide (P2O5) is too high, the concentration of amide nitrogen (Namide) is too low, and vice versa. The best ratio of P2O5 and Namide was determined when both reactants were used in a ratio of 1.0:1.0. Crystallization was carried out at 20 °C with different reaction times: 30, 60, 90 and 120 min. Analysis of the chemical composition of the synthesized urea phosphate and determination of the main components, i.e., Namide and P2O5 concentrations, were performed using standard fertilizer analysis methods. Using the optical emission spectroscopy, the concentrations of chemical elements (sulphur, aluminium, iron, calcium, magnesium, silicon, etc.) were also determined in the synthesized product. During the experiment, not only the chemical composition of the product, but also the resulting crystals of the product, and their size and shape—properties that are highly dependent on the duration of crystallization—were analysed. The thermal stability of UP crystals was investigated using simultaneous thermal analysis; the crystallinity of UP was determined using X-ray diffraction analysis; the identification of groups of chemical elements was carried out using Fourier Transform Infrared spectroscopy analysis; the shape and size of crystals were investigated using scan electron microscopy and optical microscope techniques.

О возможности синтеза β-“ядра” полиоксимолибдата железа (III) в водных растворах

This work describes for the first time the conditions for synthesizing a stable form of β-"core" iron (III) polyoxymolybdate (POM) in aqueous solutions in the form of a new molecular ("nuclear") state in a monomeric state. The optimal conditions for the formation of iron (III) POMs were determined from the light absorption of the product of the interaction of molybdate with iron (III) cations in the ultraviolet region of the spectrum. The range of light absorption of POM iron (III), kinetics and optimal acidity concerning changes in acidity, molybdate ion and exposure time after its quantitative formation were established. It has been shown that POM of iron (III) is formed at pH 3.4÷5.4, with the ratio of initial amounts ν (FeIII) :ν (MoVI) = 1:6 and is stable up to 96 hours. It has been established for the first time that, under the developed optimal conditions, iron(III) POM forms a complex associate with a low water solubility with six associated crystal violet (CV) cations, forming a very low water soluble complex associate. The obtained data indicate the formation of a new “β-core” of iron(III) POM with the composition (OH)6[H3FeMo6O18].

Abatement of environmental pollution by research on electrical resistivity and conductivity mechanism of poplar dust

Under conventional processing conditions, the resistivity of wood dust is in the range of insulating materials, which can induce a dust cloud explosion when there are static sparks. This paper took the fast-growing poplar wood commonly used in Chinese wood processing and studied the effects of moisture content, temperature, and particle size on the electrical resistivity value of sanded wood dust. Orthogonal analysis was conducted on the influencing factors. The results showed that the influence of moisture content on electrical resistivity was the most significant factor, followed by temperature and particle size. Further experiments have shown that when the moisture content increased from 6% to 32%, the resistivity decreased from 109 Ω cm to 105 Ω cm, which reached the suitable resistivity range of static discharge method. The ion concentration of wood dust extracted in cold water and hot water and the resistivity of poplar dust residue after extraction were determined. Nine metal ions (a total of 105.02 mol/g) were detected in cold-water extract, and the concentrations of K+, Na+, Mg2+ and Ca2+ accounted for 99.8%. The original poplar dust and the extracted poplar dust were measured and analyzed. The changes in water-soluble ion content, functional groups, crystallinity, and complexes of the wood dust before and after ion dissolution, jointly led to changes in the electrical resistivity of the wood dust (a difference of 2–4 orders of magnitude). It was verified that the way wood dust conducts electricity is through ion conduction. There were more abundant capillary system structures between poplar dust particles, allowing water-soluble ions to move more freely with water channels. The larger specific surface area and higher temperature also promoted the dissolution of water-soluble ions, which affected the electrical resistivity.

PSII-6 Changes in Galectin Gene Expression and Secretion in Response to Gum Arabica Drench in Goats

Abstract Acacia senegal is part of the natural diet of goats. Gum Arabica (GA) is a water-soluble complex polysaccharide antimicrobial, anti-inflammatory prebiotic, derived from Acacia Senegal. Its mechanism of action has not been defined. Galectins are secreted sugar-binding animal proteins involved in the regulation of innate and adaptive immunity. They function in microbe recognition and as regulators of inflammation. This study evaluated the effect of GA on Galectin transcription. Clinically healthy Boer X Spanish goats (n = 20) were randomly assigned to two groups of 10. Goats in the treatment group received 10 mL of GA in water daily for six weeks, controls received sterile water. Blood was collected weekly from the jugular vein using acid citrate dextrose as an anticoagulant. Subsequently, the blood was centrifuged to isolate the cells and plasma. Total RNA isolation was isolated from the cell pellet using Trizol (Sigma-Aldrich). The RNA concentration (ng/μL) and purity was assessed using a Nanodrop Spectrophotometer (Thermo Scientific Inc). Galectin-1, -3 and -9 transcription was conducted using goat specific primers and housekeeping genes for real-time PCR. Fold changes were calculated using the Livak method. The Log2FC values for Galectin 1, 3, and 9 expressions were 12.47, 0.29, and 2.22 respectively. Thus, GA had varying effects on structurally distinct galectins. Galectin 1 gene (Lgals1) is an important modulator of the immune response and was highly induced. Changes in Galectin transcription can impact microbial recognition and immune activation for goat health. Further analyses are needed to evaluate the functional effects of GA for application as a prebiotic and immune modulator lain goat health.

Complexes of Ibuprofen Thiazolidin-4-One Derivatives with β-Cyclodextrin: Characterization and In Vivo Release Profile and Biological Evaluation.

Generally, NSAIDs are weakly soluble in water and contain both hydrophilic and hydrophobic groups. One of the most widely used NSAIDs is ibuprofen, which has a poor solubility and high permeability profile. By creating dynamic, non-covalent, water-soluble inclusion complexes, cyclodextrins (CDs) can increase the dissolution rate of low aqueous solubility drugs, operating as a drug delivery vehicle, additionally contributing significantly to the chemical stability of pharmaceuticals and to reducing drug-related irritability. In order to improve the pharmacological and pharmacokinetics profile of ibuprofen, new thiazolidin-4-one derivatives of ibuprofen (4b, 4g, 4k, 4m) were complexed with β-CD, using co-precipitation and freeze-drying. The new β-CD complexes (β-CD-4b, β-CD-4g, β-CD-4k, β-CD-4m) were characterized using scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction and a phase solubility test. Using the AutoDock-VINA algorithm included in YASARA-structure software, we investigated the binding conformation of ibuprofen derivatives to β-CD and measured the binding energies. We also performed an in vivo biological evaluation of the ibuprofen derivatives and corresponding β-CD complexes, using analgesic/anti-inflammatory assays, as well as a release profile. The results support the theory that β-CD complexes (β-CD-4b, β-CD-4g, β-CD-4k, β-CD-4m) have a similar effect to ibuprofen derivatives (4b, 4g, 4k, 4m). Moreover, the β-CD complexes demonstrated a delayed release profile, which provides valuable insights into the drug-delivery area, focused on ibuprofen derivatives.

Small Molecule Pytren-4QMn Metal Complex Slows down Huntington's Disease Progression in Male zQ175 Transgenic Mice.

Huntington's disease (HD) is an inherited neurodegenerative disorder considered a rare disease with a prevalence of 5.7 per 100,000 people. It is caused by an autosomal dominant mutation consisting of expansions of trinucleotide repeats that translate into poly-glutamine enlarged mutant huntingtin proteins (mHTT), which are particularly deleterious in brain tissues. Since there is no cure for this progressive fatal disease, searches for new therapeutic approaches are much needed. The small molecule pytren-4QMn (4QMn), a highly water-soluble mimic of the enzyme superoxide dismutase, has shown in vivo beneficial anti-inflammatory activity in mice and was able to remove mHTT deposits in a C. elegans model of HD. In this study, we assessed 4QMn therapeutic potential in zQ175 neo-deleted knock-in mice, a model of HD that closely mimics the heterozygosity, genetic injury, and progressive nature of the human disease. We provide evidence that 4QMn has good acute and chronic tolerability, and can cross the blood-brain barrier, and in male, but not female, zQ175 mice moderately ameliorate HD-altered gene expression, mHtt aggregation, and HD disease phenotype. Our data highlight the importance of considering sex-specific differences when testing new therapies using animal models and postulate 4QMn as a potential novel type of small water-soluble metal complex that could be worth further investigating for its therapeutic potential in HD, as well as in other polyglutamine diseases.

Assessment of yield and profitability of Indian mustard (Brassica juncea) with foliar fertilization under rainfed condition

A field experiment was conducted during the winter (rabi) season of 2018–19, 2019–20 and 2020–21 at Dryland Agriculture Research Farm of the Chaudhary Charan Singh, Haryana Agricultural University, Hisar, to study the effect of various foliar sprays on yield and profitability of rainfed Indian mustard [Brassica juncea (L.) Czernj.]. The experiment was laid out in a randomized block design with 3 replications, comprising 7 foliar nutrition treatments, viz. control (no spray), water-spray, urea @ 1%, urea @ 2%, water-soluble complex fertilizer (18: 18: 18) @ 0.5%, 0.5% ZnSO4 spray, water-soluble complex fertilizer (18: 18: 18) @ 0.5% + 0.5% ZnSO4 . The experimental results revealed that, the growth and yield attributes, viz. plant height at harvesting, dry-matter accumulation at harvesting, number of siliquae/plants, number of branches/plant and number of seeds/siliqua, were significantly influenced by different foliar nutrition treatments except water spray. Among different foliar spray treatments, foliar spray of water-soluble complex fertilizer (18: 18: 18) @ 0.5% + 0.5% ZnSO4 resulted in significantly higher plant height at harvesting (226.1 cm), dry-matter accumulation at harvesting (99.3 g/plant), siliquae/plant (426.0), branches/plant (32.6) and seeds/siliqua (15.2). Further, the data showed that, foliar spray of water-soluble complex fertilizer (18: 18: 18) @ 0.5% + 0.5% ZnSO4 increased the seed and stover yield of Indian mustard by 30.6 and 21.1% compared with the control with higher net returns (`121,300/ha), benefit: cost ratio (4.98) and rainwater-use efficiency (75.6 kg/ha-mm).

The Blue Molybdenum Reaction for the Determination of Phosphate in Natural Water and Detergent Samples

Background:&#x0D; The ideal reaction conditions for the quantitative detection of phosphate in various natural water and detergent samples were carefully researched in order to produce and preserve the colored complex product. The blue complex was identified using a simple and accurate UV-VIS spectrophotometer with a maximum wavelength of 870 nm.&#x0D; Even though phosphate is an essential ingredient for the development of aquatic species, it is important to know exactly how much is present because an excess amount of phosphate can eutrophic water. Since detergents are one of the sources of phosphate in natural water, determining the concentration of phosphate in detergent samples is also essential.&#x0D; Materials and Methods:&#x0D; The method is based on the addition of sodium molybdate, which causes the interaction of orthophosphate with molybdate to produce an intense, stable, and water-soluble phosphomolybdate blue complex. Then, this combination is reduced using hydrazine hydrate in a sulfuric acid solution.&#x0D; Results:&#x0D; With a correlation coefficient of 0.9944, the system complies with Lambert-Beer's law at 870 nm in a concentration range of (0.05-9) ppm. Molar absorptivity was determined to be 12.16x103 L mol-1 cm-1 and Sandell's sensitivity was found to be 0.0156 g cm-2. Water samples were collected from Warte, Choman, Jundeyan, and Bexal in Kurdistan's vicinity of Soran. Further, detergent samples that were obtained from the market and their phosphate level were examined. The Bexal waterfall had the lowest concentration of phosphate, 0.18 ppm, while the Warte and Jundeyan water samples had the highest concentrations, 3.31 ppm, and 3.04 ppm, respectively. Moreover, similar phosphate concentrations in the two detergent samples were discovered to be at 20.43 and 24.76 ppm.&#x0D; Conclusion:&#x0D; The molybdenum blue reaction has been successfully employed to provide a sensitive and quick measuring method to quantify the phosphate content in various water and detergent samples using UV-VIS spectrophotometry by applying the right reaction conditions and reagent quantities.

Nb2O5-graphene heterojunction composite with ultrahigh photocatalytic activity for solar light driven photodegradation of ciprofloxacin

Poor visible light absorption capacity and intrinsic conductivity restrict many applications of Nb2O5 in photocatalysis. The paper describes one solution for synthesizing Nb2O5-graphene photocatalyst with functional graphene quantum dot (GQD). Firstly, Nb(V) was coordinated with GQD to form water-soluble complex. Then, it was bound to graphene sheet via π-π stacking, reduced with ascorbic acid to produce graphene oxide gel and annealed in N2 at 900 °C. The resultant Nb2O5 nanocrystals offer ultrasmall size of 8.8 ± 0.6 nm and good crystallinity. The introduction of GQD realizes the construction of heterojunction. This narrows bandgap energy of Nb2O5 and optimizes the band structure. The narrowed bandgap energy leads to an enhanced visible light absorption, and more negative conduction band potential and more positive valence band potential promote production of superoxide (•O2–) and hydroxyl radicals (•OH). Combination of graphene with GQD improves adsorption of ciprofloxacin, separation of generated electrons and holes and light absorption capacity. G-Nb2O5-900 exhibits an excellent photocatalytic performance for solar light driven photodegradation of ciprofloxacin. The photodegradation efficiency is more than 3.58 times under ultraviolet light radiation and 12.4 times under visible light radiation over pristine Nb2O5. G-Nb2O5-900 shows a broad application prospect in antibiotic treatment in environmental water.

Biological activity of two water-soluble amino acid-Pt complexes: Synthesis, characterization, cytotoxicity, DNA interaction, and theoretical studies

In the present work, two water-soluble amino acid–Pt complexes, [Pt(phd)(AA)]ClO4, (phd = 1,10-phenanthroline-5,6-dione; 1, AA = L-isoleucine and 2, AA = L-leucine) have been introduced. The preparation and characterization of two novel water-soluble platinum complexes were performed. Molecular docking, ADME, and DFT were used to study these complexes theoretically. The mechanism of DNA binding was studied using fluorescence, UV–Vis, and CD spectroscopy. Fluorescence data indicated a static mechanism for quenching DNA. According to thermodynamic parameters, DNA and Pt(II) complexes interact via groove binding and intercalation. CD spectra indicated that both complexes show an increase in intensity across all bands. Experimental data agree with docking studies and DFT calculations. In sum, groove binding and intercalation are the mechanisms of binding to DNA. Based on cytotoxicity studies, both complexes showed higher anticancer activity against A2780SP cell line than cisplatin. Moreover, complex 2 is more active than complex 1 according to all theoretical and experimental evidence.

Anti-stokes fluorescence of phycobilisome and its complex with the orange carotenoid protein

Phycobilisomes (PBSs) are giant water-soluble light-harvesting complexes of cyanobacteria and red algae, consisting of hundreds of phycobiliproteins precisely organized to deliver the energy of absorbed light to chlorophyll chromophores of the photosynthetic electron-transport chain. Quenching the excess of excitation energy is necessary for the photoprotection of photosynthetic apparatus. In cyanobacteria, quenching of PBS excitation is provided by the Orange Carotenoid Protein (OCP), which is activated under high light conditions. In this work, we describe parameters of anti-Stokes fluorescence of cyanobacterial PBSs in quenched and unquenched states. We compare the fluorescence readout from entire phycobilisomes and their fragments. The obtained results revealed the heterogeneity of conformations of chromophores in isolated phycobiliproteins, while such heterogeneity was not observed in the entire PBS. Under excitation by low-energy quanta, we did not detect a significant uphill energy transfer from the core to the peripheral rods of PBS, while the one from the terminal emitters to the bulk allophycocyanin chromophores is highly probable. We show that this direction of energy migration does not eliminate fluorescence quenching in the complex with OCP. Thus, long-wave excitation provides new insights into the pathways of energy conversion in the phycobilisome.

A promising synthetic citric crosslinked β-cyclodextrin derivative for antifungal drugs: Solubilization, cytotoxicity, and antifungal activity

Effective antifungal therapy for the treatment of fungal keratitis requires a high drug concentration at the corneal surface. However, the use of natural β-cyclodextrin (βCD) in the preparation of aqueous eye drop formulations for treating fungal keratitis is limited by its low aqueous solubility. Here, we synthesized water-soluble anionic βCD derivatives capable of forming water-soluble complexes and evaluated the solubility, cytotoxicity, and antifungal efficacy of drug prepared using the βCD derivative. To achieve this, a citric acid crosslinked βCD (polyCTR-βCD) was successfully synthesized, and the aqueous solubilities of selected antifungal drugs, including voriconazole, miconazole (MCZ), itraconazole, and amphotericin B, in polyCTR-βCD and analogous βCD solutions were evaluated. Among the drugs tested, complexation of MCZ with polyCTR-βCD (MCZ/polyCTR-βCD) increased MCZ aqueous solubility by 95-fold compared with that of MCZ/βCD. The inclusion complex formation of MCZ/βCD and MCZ/polyCTR-βCD was confirmed by spectroscopic techniques. Additionally, the nanoaggregates of saturated MCZ/polyCTR-βCD and MCZ/βCD solutions were observed using dynamic light scattering and transmission electron microscopy. Moreover, MCZ/polyCTR-βCD solution exhibited good mucoadhesion, sustained drug release, and high drug permeation of porcine cornea ex vivo. Hen’s Egg test-chorioallantoic membrane assay and cell viability study using Statens Seruminstitut Rabbit Cornea cell line showed that both MCZ/polyCTR-βCD and MCZ/βCD exhibited no sign of irritation and non-toxic to cell line. Additionally, antifungal activity evaluation demonstrated that all isolated fungi, including Candida albicans, Aspergillus flavus, and Fusarium solani, were susceptible to MCZ/polyCTR-βCD. Overall, the results showed that polyCTR-βCD could be a promising nanocarrier for the ocular delivery of MCZ.

Synthesis and study of composite materials based on apple pectin and copper cations

The paper presents the results of synthesis the metal-composite materials based on apple pectin and divalent metal cations - Cu2+; determining the degree of esterification and the content of free carboxyl groups of the native pectin by acid-base titration, determining the degree of inclusion of the specified cation in the polysaccharide macromolecule and studying by IR spectroscopy and fungicidal activity of native pectin and copper complexes against Penicillum sp According to the results of titration, it was found that apple pectin has a high degree of esterification (DE = 50.7%) and a low content of carboxyl groups (Kc = 2.79%), which suggests its low gelling activity. It was found that the increase in salt concentration is above 0.005 g-eq/l. leads to a decrease in the proportion of the resulting water-soluble complex. The optimal concentration of CuSO4 5H2O, at which the largest mass of the water-soluble complex is formed, is 0.005 g-eq/l. According to IR spectroscopy, the degree of substitution of sodium cations for copper cations was calculated, which amounted to 18%. It was shown that the native apple pectin does not have fungicidal activity, while the copper complex based on it is able to suppress the growth of the culture already under the action of 10 µl of the substance, and with an increase in volume to 50 µl, an even more active fungicidal activity of the copper complex appears.