Effects of melatonin on inhibiting quality deterioration of postharvest water bamboo shoots.

Water bamboo shoots (Zizania latifolia) is prone to quality deterioration during cold storage after harvest, which causes the decline of commodity value. Chlorophyll synthesis and lignin deposition are the major reasons for quality degradation. This paper studied the influence of exogenous melatonin (MT) on the cold storage quality of water bamboo shoots. MT treatment could delay the increase in skin browning, hardness and weight loss rate, inhibit chlorophyll synthesis and color change of water bamboo shoots, while maintain the content of total phenols and flavonoids, and inhibit lignin deposition by inhibiting the activity and gene expression of phenylpropanoid metabolism related enzymes as PAL, C4H, 4CL, CAD, and POD. The results indicate that exogenous MT treatment can effectively inhibit the quality degradation of cold stored water bamboo shoots.

Design, Synthesis, Anti-Inflammatory Activity, DFT Modeling and Docking Study of New Ibuprofen Derivatives.

A new ibuprofen derivative, (E)-2-(4-isobutylphenyl)-N'-(4-oxopentan-2-ylidene) propane hydrazide (IA), was synthesized, along with its metal complexes with Co, Cu, Ni, Gd, and Sm, to investigate their anti-inflammatory efficacy and COX-2 inhibition potential. Comprehensive characterization, including 1H NMR, MS, FTIR, UV-vis spectroscopy, and DFT analysis, were employed to determine the structural configurations, revealing unique motifs for Gd/Sm (capped square antiprismatic/tricapped trigonal prismatic) and Cu/Ni/Co (octahedral) complexes. Molecular docking with the COX-2 enzyme (PDB code: 5IKT) and pharmacokinetic assessments through SwissADME indicated that these compounds have superior binding energies and pharmacokinetic profiles, including BBB permeability and gastrointestinal absorption, compared to the traditional ibuprofen standalone. Their significantly lower IC50 values further suggest a higher efficacy as anti-inflammatory agents and COX-2 inhibitors. These research findings not only introduce promising ibuprofen derivatives for therapeutic applications but also set the stage for future validation and exploration of this new generation of ibuprofen compounds.

Multistep pH-peak-focusing liquid chromatography with a hydrophilic polymer gel column for separation of rare earth elements.

Multistep pH-peak-focusing liquid chromatography with a column packed with a hydrophilic polymer gel (a cross-linked hydroxylated methacrylic polymer gel) was developed for separation of rare earth metal ions. Metal ions in a sample solution introduced to the column are chromatographically extracted into the stationary gel phase at the top of the column equilibrated with a basic solution used as the first mobile phase containing acetylacetone and 1,10-phenanthroline by synergistic extraction effect. After the sample solution is introduced, the mobile phases are delivered into the column by stepwise gradient elution in order of decreasing pH. Each metal ion is concentrated at a pH border formed between the zones of different pH in the column and moves toward the outlet of the column with the pH border. Mutual separation of La(III), Ce(III), Nd(III), Eu(III), Y(III), Tb(III), and Yb(III) was achieved by the present method for an 1-mL sample injection with the column of which the inner volume is 11.8 mL. The multistep pH-peak-focusing liquid chromatography with a hydrophilic polymer gel column developed in this study has great potential as a useful method for the separation of rare earth metal ions on a preparatory scale.

Mechanisms of isomerization and hydration reactions of typical ß-diketone at the air-droplet interface.

Acetylacetone (AcAc) is a typical class of ß-diketones with broad industrial applications due to the property of the keto-enol isomers, but its isomerization and chemical reactions at the air-droplet interface are still unclear. Hence, using combined molecular dynamics and quantum chemistry methods, the heterogeneous chemistry of AcAc at the air-droplet interface was investigated, including the attraction of AcAc isomers by the droplets, the distribution of isomers at the air-droplet interface, and the hydration reactions of isomers at the air-droplet interface. The results reveal that the preferential orientation of two AcAc isomers (keto- and enol-AcAc) to accumulate and accommodate at the acidic air-droplet interface. The isomerization of two AcAc isomers at the acidic air-droplet interface is more favorable than that at the neutral air-droplet interface because the "water bridge" structure is destroyed by H3O+, especially for the isomerization from keto-AcAc to enol-AcAc. At the acidic air-droplet interface, the carbonyl or hydroxyl O-atoms of two AcAc isomers display an energetical preference to hydration. Keto-diol is the dominant products to accumulate at the air-droplet interface, and excessive keto-diol can enter the droplet interior to engage in the oligomerization. The photooxidation reaction of AcAc will increase the acidity of the air-droplet interface, which indirectly facilitate the uptake and formation of more keto-diol. Our results provide an insight into the heterogeneous chemistry of ß-diketones and their influence on the environment.

Unleashing the power of acetylacetone: Effective control of harmful cyanobacterial blooms with ecological safety.

Harmful algal blooms resulting from eutrophication pose a severe threat to human health. Acetylacetone (AA) has emerged as a potential chemical for combatting cyanobacterial blooms, but its real-world application remains limited. In this study, we conducted a 42-day evaluation of AA's effectiveness in controlling blooms in river water, with a focus on the interplay between ecological community structure, organism functional traits, and water quality. At a concentration of 0.2 mM, AA effectively suppressed the growth of Cyanobacteria (88 %), Bacteroidia (49 %), and Alphaproteobacteria (52 %), while promoting the abundance of Gammaproteobacteria (5.0 times) and Actinobacteria (7.2 times) that are associated with the degradation of organic matter. Notably, after dosing of AA, the OD680 (0.07 ± 0.02) and turbidity (8.6 ± 2.1) remained at a satisfactory level. AA induced significant disruptions in two photosynthesis and two biosynthesis pathways (P < 0.05), while simultaneously enriching eight pathways of xenobiotics biodegradation and metabolism. This enrichment facilitated the reduction of organic pollutants and supported improved water quality. Importantly, AA treatment decreased the abundance of two macrolide-related antibiotic resistance genes (ARGs), ereA and vatE, while slightly increased the abundance of two aminoglycoside-related ARGs, aacA and strB. Overall, our findings establish AA as an efficient and durable algicide with favorable ecological safety. Moreover, this work contributes to the development of effective strategies for maintaining and restoring the health and resilience of aquatic ecosystems impacted by harmful algal blooms.

Selenite-Catalyzed Reaction between Benzoquinone and Acetylacetone Deciphered the Enhanced Inhibition on Microcystis aeruginosa Growth.

The coexistence of selenite (Se(IV)) and acetylacetone (AA) generated a synergistic effect on the growth inhibition of a bloom-forming cyanobacterium, Microcystis aeruginosa. The mechanism behind this phenomenon is of great significance in the control of harmful algal blooms. To elucidate the role of Se(IV) in this effect, the reactions in ternary solutions composed of Se(IV), AA (or two other similar hydrogen donors), and quinones, especially benzoquinone (BQ), were investigated. The transformation kinetic results demonstrate that Se(IV) played a catalytic role in the reactions between AA (or ascorbic acid) and quinones. By comparison with five other oxyanions (sulfite, sulfate, nitrite, nitrate, and phosphate) and two AA derivatives, the formation of an AA-Se(IV) complexation intermediate was confirmed as a key step in the accelerated reactions between BQ and AA. To our knowledge, this is the first report on Se(IV) as a catalyst for quinone-involved reactions. Since both quinones and Se are essential in cells and there are many other chemicals of similar electron-donating properties to that of AA, the finding here shed light on the regulation of electron transport chains in a variety of processes, especially the redox balances that are tuned by quinones and glutathione.

Multifunctional Cd-CP for fluorescence sensing of Cr(VI), MnO4-, acetylacetone and ascorbic acid in aqueous solutions.

The development of multifunctional fluorescent chemosensors for the detection of multiple targets remains challenging but of great importance. In this paper, one novel coordination polymer (CP), denoted as [Cd2(edda)(phen)2]∙H2O (compound 1, H4edda = 5,5' (ethane-1,2-diylbis(oxy)) diisophthalic acid, phen = 1,10-phenanthroline) is successfully designed and prepared under hydrothermal conditions. Structural analysis indicates that compound 1 possesses a one-dimensional (1D) double chain structure, then self-assembles into a three-dimensional (3D) supramolecular framework via π…π interactions between phen molecules. Interestingly, compound 1 is found to be tolerant in wide range of acidic to alkaline aqueous solutions (pH = 2-13). Fluorescent spectral investigations reveal that compound 1 exhibits highly selective and sensitive fluorescence responses toward MnO4-, Cr(VI) ions, acetylacetone (acac) and ascorbic acid (AA) by fluorescence quenching in the aqueous phase. The detection limits are in the very low range, reaching µM level for the detection of MnO4-, Cr(VI) ions, nM for AA and ppm for acac detection. The distinguished multi-responsive performance suggests compound 1 to be a potential multifunctional probe. Furthermore, the possible quenching mechanisms have also been systematically investigated in this work.

A water-stable dual-responsive Cd-CP for fluorometric recognition of hypochlorite and acetylacetone in aqueous media.

One novel cadmium(II)-coordination polymer [Cd3L2(datrz)(H2O)3] (CP 1) is controllably synthesized by surmising the astute combination of semi-rigid tricarboxylate acid 4-(2',3'-dicarboxylphenoxy) benzoic acid (H3L) and auxiliary ligand 3,5-diamino-1,2,4-triazole (datrz). Structure analysis shows that CP 1 has a two-dimensional (2D) layer structure with a 5-nodal (43) (44·62) (45·64·8) (45·6) (47·66·82) topology. Further investigations reveal that CP 1 shows superordinary water stability and good thermal stability. The fluorescent explorations suggest that the as-synthesized CP 1 could emit blue light centered at 485 nm, attributing to ligand-based emission. In terms of sensing investigations, CP 1 could act as a fluorescent sensor for detecting hypochlorite (ClO-) and acetylacetone (acac) through fluorescence turn-off process in aqueous solution, and the detection limit could reach 0.18 µM and 0.056 µM, respectively. Further research reveals that it is more likely the N-H···O-Cl hydrogen bonds between -NH2 groups of the triazole ligands and O atoms of ClO- plays the key role in the system, which may serve as a bridge for the energy transfer, leading to fluorescence quenching of the chemosensor. While the photoinduced electron transfer (PET) combined with inner filter effect (IFT) should be responsible for the turn-off fluorescence of CP 1 triggered by acac.

[Determination of acetylacetone in workplace air by solvent desorption-gas chromatography].

Objective: To establish a method for the determination of acetylacetone in the air of workplace by gas chromatography. Methods: In August 2020, acetylacetone in the air of workplace was collected by silica gel tube, eluted with methanol, separated and detected by gas chromatography with flame ionization detector. The detection limit and precision of the method were also analyzed. Results: The linear range of acetylacetone was 1.95-1950.60 µg/ml with the regression equation of y=0.815x-3.667, and the correlation coefficient was 0.99993. The limit of detection of the method was 0.18 µg/ml and the minimum detection concentration was 0.12 mg/m(3) (collected sample volume was 1.50 L). The within-run precisions were 1.08%-4.11% and the between-run precisions were 1.98%-2.80%. The desorption rates were 99.68%-100.45%. The sealed samples could be kept at least 15 days at room temperature without significant loss. Conclusion: The solvent desorption-gas chromatography method for the determination of acetylacetone has good precision, high sensitivity and simple operation, and is suitable for the determination of acetylacetone in the air of the workplace.

Effects of a redox-active diketone on the photochemical transformation of roxarsone: Mechanisms and environmental implications.

Organoarsenical antibiotics pose a severe threat to the environment and human health. In aquatic environment, dissolved organic matter (DOM)-mediated photochemical transformation is one of the main processes in the fate of organoarsenics. Dicarbonyl is a typical redox-active moiety in DOM. However, the knowledge on the photoconversion of organoarsenics by DOM, especially the contributions of dicarbonyl moieties is still limited. Here, we systematically investigated the photochemical transformation of three organoarsenics with the simplest ß-diketone, acetylacetone (AcAc), as a model dicarbonyl moiety of DOM. The presence of AcAc significantly enhanced the photochemical conversion of roxarsone (ROX), whereas only minor effects were observed for 3-amino-4-hydroxyphenylarsonic acid (HAPA) and arsanilic acid (ASA), because the latter two (with an amino (-NH2) group) are more photoactive than ROX (with a nitro (-NO2) group). The results demonstrate that AcAc was a potent photo-activator and the reduction of -NO2 to -NH2 might be a rate-limiting step in the phototransformation of ROX. At a 1:1 M ratio of AcAc to ROX, the photochemical transformation rate of ROX was increased by 7 folds. In O2-rich environment, singlet oxygen, peroxide radicals, and ·OH were the main reactive species that led to the breakage of the C-As bond in ROX and the oxidation of the released arsono group to arsenate, whereas the triplet-excited state of AcAc (3AcAc*) and carbon-centered radicals from the photolysis of AcAc dominated in the reductive transformation of ROX. In anoxic environment, 3-amino-4-hydroxyphenylarsonic acid was one of the main reductive transformation intermediates of ROX, whose photolysis rate was about 35 times that of ROX. The knowledge obtained here is of great significance to better understand the fate of organoarsenics in natural environment.

UV-Vis Spectroscopy, Electrochemical and DFT Study of Tris(ß-diketonato)iron(III) Complexes with Application in DSSC: Role of Aromatic Thienyl Groups.

A series of tris(ß-diketonato)iron(III) complexes, with the ß-diketonato ligand bearing different substituent groups, have been synthesized and characterized by Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis) and mass spectroscopic methods. The maximum band UV-Vis absorption wavelengths of the tris(ß-diketonato)iron(III) complexes were in the range of 270-380 nm. The complexes have very good solubility in various solvents such as chloroform, dichloromethane, ethyl acetate, tetrahydrofurane, dimethylsulphoxide and dimethylformamide. After the syntheses and characterization processes, spectroscopic and electrochemical properties of these tris(ß-diketonato)iron(III) complexes were investigated. A density functional theory (DFT) study related to the spectroscopic and electrochemical properties of the tris(ß-diketonato)iron(III) complexes was used to investigate the possible application of these complexes as dye sensitizers or redox mediators in dye-sensitized solar cells.

Peroxyl radicals from diketones enhanced the indirect photochemical transformation of carbamazepine: Kinetics, mechanisms, and products.

In surface waters, photogenerated transients (e.g., hydroxyl radicals, carbonate radicals, singlet oxygen and the triplet states of dissolved organic matter) are known to play a role in the transformation of biorecalcitrant carbamazepine (CBZ). Small diketones, such as acetylacetone (AcAc) and butanedione (BD), are naturally abundant and have been proven to be effective precursors of carbon and oxygen centered radicals. However, the photochemical kinetics and mechanisms of coexisting diketones and CBZ are barely known. Herein, the effects of AcAc and BD on the photochemical conversion of CBZ were investigated compared with H2O2 which was the main ·OH precursor in the environment. An enhancing effect was observed for the degradation of CBZ by the addition of diketones. The enhancing effect of diketones was pH-dependent and much more significant than H2O2 under simulated solar irradiation. On the basis of the identification of transient species and the competition kinetic model, organic peroxyl radicals were found to play a dominant role in CBZ photodegradation, and the second-order rate constants of the reaction between CBZ and peroxyl radicals were determined to be approximately 107-108 M-1s-1. Furthermore, mutagenic acridine was found to be the major cumulative intermediate with a yield of > 30% in the presence of diketones, which might be an environmental concern. This work indicates that the coexistence of diketones and persistent organic pollutants might lead to some detrimental effects on aquatic environments if the water is exposed to sunlight.

Discrimination of Excited States of Acetylacetone through Theoretical Molecular-Frame Photoelectron Angular Distributions.

Photoelectron angular distribution (PAD) in the laboratory frame for randomly oriented molecules is typically described by a single anisotropy parameter, the so-called asymmetry parameter. However, especially from a theoretical perspective, it is more natural to consider molecular photoionization by using a molecular frame. The molecular frame PADs (MFPADs) may be used to extract information about the electronic structure of the system studied. In the last decade, significant experimental efforts have been directed to MFPAD measurements. MFPADs are highly characterizing signatures of the final ionic states. In particular, they are very sensitive to the nature of the final state, which is embodied in the corresponding Dyson orbital. In our previous work on acetylacetone, a prototype system for studying intra-molecular hydrogen bond interactions, we followed the dynamics of the excited states involved in the photoexcitation-deexcitation process of this molecule. It remains to be explored the possibility of discriminating between different excited states through the MFPAD profiles. The calculation of MFPADs to differentiate excited states can pave the way to the possibility of a clear discrimination for all the cases where the recognition of excited states is otherwise intricate.

Subtle Ligand Spacer Change in 2D Metal-Organic Framework Sheets for Dual Turn-On/Turn-Off Sensing of Acetylacetone and Turn-On Sensing of Water in Organic Solvents.

Metal-organic framework (MOF)-based sensors for the detection of various analyte molecules has been a subject of absolute importance. However, most of these sensors rely on the turn-off (quenching) transduction response, while those reporting turn-on response are very rare. In this article, we have synthesized two new MOF-based sensors, {[Zn2(oxdz)2(tpbn)]·14H2O}n (1) and {[Zn2(oxdz)2(tpxn)]·10H2O·2C2H5OH}n (2), via the self-assembly of Zn(II) metal ions, a fluorogenic oxdz2- linker, and bis(tridentate) ligands (tpbn and tpxn) under ambient conditions. Their formation from such a self-assembly process has been evaluated on the basis of the geometry around the five-coordinated Zn(II), preferential meridional binding of the bis(tridentate) ligands, and diverse binding of the carboxylate groups in oxdz2-. Although 1 and 2 are isostructural, a difference in the transduction mechanism for the sensing of acetylacetone in organic solvents (turn-on for 1 and turn-off for 2) is observed and can be attributed to the spacer in the bis(tridentate) ligands. We have demonstrated the competing effect of the nonradiative interactions and photoinduced electron transfer toward the sensing mechanism. The results are well-supported by the Fourier transform infrared spectroscopy study, intensity versus concentration plots, spectral overlap measurements, time-resolved fluorescence studies, and MM2 and density functional theory calculations. Furthermore, we have showcased the utilization of 1 for the sensing of trace amounts of water in organic solvents.

Doxorubicin delivery systems with an acetylacetone-based block in cholesterol-terminated copolymers: Diverse activity against estrogen-dependent and estrogen-independent breast cancer cells.

The study presents the synthesis of original cholesterol-terminated copolymers comprising acetylacetone-based (AcacI) and N-isopropylacrylamide (NIPAAm) units with a varied arrangement (block and random copolymers). The nanoprecipitation method was used to form empty and doxorubicin-loaded polymeric nanoparticles (PNPs) from these copolymers, which were further studied in terms of their physicochemical and biological properties. Unexpectedly, it was revealed that even empty PNPs are effective against breast cancer cells, specifically towards estrogen-dependent MCF-7 cell line. The anti-cancer efficacy was further improved when a low dose of doxorubicin was introduced to the tested systems. It was shown that the proposed carriers modulate doxorubicin (DOX) compatibility with representatives of normal cells, including immune cells, cardiomyocyte cells, and fibroblasts, and reduce side effects associated with standard chemotherapy. The use of these carriers might be a strategy leading to enhancement of DOX activity in cancer cells which develop resistance through decreased drug penetration or drug efflux.

A cholesterol benzoate RRS probe for the determination of trace ammonium ions.

The measurement of NH4+ has attracted considerable attention with the increase of NH4+ emissions in sewage caused by human activities. So far, a variety of photometric and fluorescence methods for the detection of NH4+ have been researched and summarized, but there is no report about the use of liquid crystals (LCs) cholesteryl benzoate (CB) as a resonance Rayleigh scattering (RRS) probe to determine ammonium ions. In the NaAc-HAc buffer solution with pH = 4.80, the yellow compounds 3,5 diacetyl-1,4 dihydrolutidine (DDL) generated by the reaction of NH4+ with acetylacetone (AT) and formaldehyde (HCHO) act as the energy receiver and CB as the donor. Because the RRS spectrum of CB overlaps with the DDL absorption spectrum, resonance Rayleigh scattering energy transfer (RRS-ET) occurs. When the NH4+ concentration increased, the generated DDL increased, and the RRS-ET also increased, so the RRS intensity of the system at 395 nm decreased. For this reason, a fast and sensitive CB RRS-ET method was established to apply to the detection of NH4+ in water. The detection range was 1.00 × 10-3 - 4.66 µg/mL, and the detection limit was 6.62 × 10-3 µg/mL. Using this method to analyze and detect NH4+ in environmental water samples, the precision and recovery rate were between 1.30-9.30% and 95.5-109.9%, respectively. Therefore, this method has the advantages of sensitivity and simplicity.

A novel isosteviol-based bifunctional squaramide organocatalyst for enantioselective Michael addition of acetylacetone to nitroolefins.

Chiral amine-squaramide is a kind of effective hydrogen bond donor bifunctional catalyst to promote many asymmetric transformations. In this paper, novel chiral tertiary amine-squaramide derived from the natural product of the stevioside was developed and applied into the asymmetric Michael addition of acetylacetone to nitroolefins. This asymmetric reaction performed well, and a series of enantiomerically enriched compounds were obtained in high yields (up to 96%) with excellent enantioselectivities (up to 99% ee).

Regulation of Photosynthesis in Bloom-Forming Cyanobacteria with the Simplest ß-Diketone.

Selective inhibition of photosynthesis is a fundamental strategy to solve the global challenge caused by harmful cyanobacterial blooms. However, there is a lack of specificity of the currently used cyanocides, because most of them act on cyanobacteria by generating nontargeted oxidative stress. Here, for the first time, we find that the simplest ß-diketone, acetylacetone, is a promising specific cyanocide, which acts on Microcystis aeruginosa through targeted binding on bound iron species in the photosynthetic electron transport chain, rather than by oxidizing the components of the photosynthetic apparatus. The targeted binding approach outperforms the general oxidation mechanism in terms of specificity and eco-safety. Given the essential role of photosynthesis in both natural and artificial systems, this finding not only provides a unique solution for the selective control of cyanobacteria but also sheds new light on the ways to modulate photosynthesis.

Stable Bicyclic Functionalized Nitroxides: The Synthesis of Derivatives of Aza-nortropinone-5-Methyl-3-oxo-6,8-diazabicyclo[3.2.1]-6-octene 8-oxyls.

In recent decades, bicyclic nitroxyl radicals have caught chemists' attention as selective catalysts for the oxidation of alcohols and amines and as additives and mediators in directed C-H oxidative transformations. In this regard, the design and development of synthetic approaches to new functional bicyclic nitroxides is a relevant and important issue. It has been reported that imidazo[1,2-b]isoxazoles formed during the condensation of acetylacetone with 2-hydroxyaminooximes having a secondary hydroxyamino group are recyclized under mild basic catalyzed conditions to 8-hydroxy-5-methyl-3-oxo-6,8-diazabicyclo[3.2.1]-6-octenes. The latter, containing a sterically hindered cyclic N-hydroxy group, upon oxidation with lead dioxide in acetone, virtually quantitatively form stable nitroxyl bicyclic radicals of a new class, which are derivatives of both 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (TEMPON) and 3-imidazolines.

Selective adsorption of flavonoids on cerium-doped ferroferric oxide magnetic particles.

Ce-doped Fe3O4 magnetic particles (Ce-Fe3O4 MPs) were synthesized by co-precipitation method. The coordination and adsorption properties of Ce-Fe3O4 MPs to different natural products were investigated. The results verified that the "catechol-like","maltol-like" and "acetylacetone-like" donor sets of flavonoids were the binding sites with Ce-Fe3O4 MPs. The adsorption was conformed to be pseudo-second-order model and single-layer adsorption after being characterized by adsorption kinetics and adsorption thermodynamics. The adsorption and desorption conditions were optimized. It was found that different components adsorbed on the Ce-Fe3O4 MPs surface can be selective desorbed in different solvents, which was helpful for the selective separation to adsorbed components. The Ce-Fe3O4 MPs were successfully applied to selective adsorption of compounds containing "catechol-like", "maltol-like" and "acetylacetone-like" donor sets in the crude extract of Scutellaria baicalensis Georgi and Rheum palmatum L. The results demonstrated that the magnetic solid phase extraction (MSPE) method based on Ce-Fe3O4 MPs has the advantages of high structural selectivity, high efficiency and low consumption, and can be used for efficient separation of flavonoids with specific structures from natural products.