Tungsten sulfide highly boosted Fe(III)/peroxymonosulfate system for rapid degradation of cyclohexanecarboxylic acid: Performance, mechanisms, and applications.

In this study, the Fe(III)/WS2/peroxymonosulfate (PMS) system was found to remove up to 97% of cyclohexanecarboxylic acid (CHA) within 10 min. CHA is a model compound for naphthenic acids (NAs), which are prevalent in petroleum industrial wastewater. The addition of WS2 effectively activated the Fe(III)/PMS system, significantly enhancing its ability to produce reactive oxidative species (ROS) for the oxidation of CHA. Further experimental results and characterization analyses demonstrated that the metallic element W(IV) in WS2 could provide electrons for the direct reduction of Fe(III) to Fe(II), thus rapidly activating PMS and initiating a chain redox process to produce ROS (SO4•-, •OH, and 1O2). Repeated tests and practical exploratory experiments indicated that WS2 exhibited excellent catalytic performance, reusability and anti-interference capacity, achieving efficient degradation of commercial NAs mixtures. Therefore, applying WS2 to catalyze the Fe(III)/PMS system can overcome speed limitations and facilitate simple, economical engineering applications.

Discovery and Biosynthesis of Streptolateritic Acids A-D: Acyclic Pentacarboxylic Acids from Streptomyces sp. FXJ1.172 with Promising Activity against Potato Common Scab.

Potato common scab (PCS) is a widespread plant disease that lacks effective control measures. Using a small molecule elicitor, we activate the production of a novel class of polyketide antibiotics, streptolateritic acids A-D, in Streptomyces sp. FXJ1.172. These compounds show a promising control efficacy against PCS and an unusual acyclic pentacarboxylic acid structure. A gene cluster encoding a type I modular polyketide synthase is identified to be responsible for the biosynthesis of these metabolites. A cytochrome P450 (CYP) and an aldehyde dehydrogenase (ADH) encoded by two genes in the cluster are proposed to catalyze iterative oxidation of the starter-unit-derived methyl group and three of six branching methyl groups to carboxylic acids during chain assembly. Our findings highlight how activation of silent biosynthetic gene clusters can be employed to discover completely new natural product classes able to combat PCS and new types of modular polyketide synthase-based biosynthetic machinery.

Synthesis of 1H-isoindolin-1-ones via a simple photodecarboxylative addition of carboxylates to phthalimides and evaluation of their antibiotic activity.

A variety of 3-hydroxy-isoindolin-1-one derivatives were synthesized using the photodecarboxylative addition of carboxylates to phthalimide derivatives in aqueous media. Subsequent acid-catalyzed dehydration furnished 3-(alkyl and aryl)methyleneisoindolin-1-ones with variable E-diastereoselectivity in good to excellent overall yields. Noteworthy, the parent 3-phenylmethyleneisoindolin-1-one underwent isomerization and oxidative decomposition when exposed to light and air. Selected 3-hydroxy-isoindolin-1-one and 3-(alkyl and aryl)methyleneisoindolin-1-one derivatives showed moderate antibacterial activity that justifies future elaboration and study of these important bioactive scaffolds.

Synthesis of (2R,4S)-4-Amino-5-hydroxybicyclo[3.1.1]heptane-2-carboxylic Acid via an Asymmetric Intramolecular Mannich Reaction.

Inhibition of human ornithine aminotransferase interferes with glutamine and proline metabolism in hepatocellular carcinoma, depriving tumors of essential nutrients. A proposed mechanism-based inhibitor containing a bicyclo[3.1.1]heptanol warhead is reported herein. The proposed inactivation mechanism involves a novel α-iminol rearrangement. The synthesis of the proposed inhibitor features an asymmetric intramolecular Mannich reaction, utilizing a chiral sulfinamide. This study presents a novel approach toward the synthesis of functionalized bicyclo[3.1.1]heptanes and highlights an underutilized method to access enantiopure exocyclic amines.

Building Block-Centric Approach to DNA-Encoded Library Design.

DNA-encoded library technology grants access to nearly infinite opportunities to explore the chemical structure space for drug discovery. Successful navigation depends on the design and synthesis of libraries with appropriate physicochemical properties (PCPs) and structural diversity while aligning with practical considerations. To this end, we analyze combinatorial library design constraints including the number of chemistry cycles, bond construction strategies, and building block (BB) class selection in pursuit of ideal library designs. We compare two-cycle library designs (amino acid + carboxylic acid, primary amine + carboxylic acid) in the context of PCPs and chemical space coverage, given different BB selection strategies and constraints. We find that broad availability of amines and acids is essential for enabling the widest exploration of chemical space. Surprisingly, cost is not a driving factor, and virtually, the same chemical space can be explored with "budget" BBs.

Comparative study of polycarboxylic acids for sustainable crosslinking of silk fabrics: Evaluating flame retardancy and physical performances.

For protein fibers, polycarboxylic acids represent a green strategy to enhance durability without using formaldehyde. This study evaluated the physical and flame retardant properties of silk fabrics treated with three formaldehyde-free crosslinkers: citric acid (CA), 1,2,3,4-butanetetracarboxylic acid (BTCA), and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA). Results showed that these acids bond with silk protein through esterification and amidation, improving washing durability. Particularly, PBTCA integrates phosphorus into silk, boosting flame retardancy. While BTCA led to the highest weight gain and improved wrinkle recovery, it negatively impacted the tensile strength and softness of silk fabrics. Conversely, PBTCA adeptly balanced enhanced wrinkle resistance with minimal effects on tensile strength and softness, and least affected the silk fabrics' whiteness, thus preserving its aesthetic appeal. All crosslinkers improved flame retardancy, but PBTCA displayed superior performance, achieving a limiting oxygen index of 32.4 % at an 80 g/L concentration. In vertical burning tests, PBTCA treated silk fabrics showed reductions in damage length and demonstrated self-extinguishing properties, qualifying them for a higher flame retardant grade. Phosphorus in PBTCA promotes char formation during combustion, essential for effective flame retardation and smoke reduction. This research highlights the exceptional potential of silk treated with PBTCA, showcasing its suitability for demanding applications.

Adsorptive features of cyclohexane carboxylic naphthenic acid on a novel cross-linked polymer developed from spent coffee grounds.

Naphthenic acids (NA) are organic compounds commonly found in crude oil and produced water, known for their recalcitrance and toxicity. This study introduces a new adsorbent, a polymer derived from spent coffee grounds (SCGs), through a straightforward cross-linking method for removing cyclohexane carboxylic acid as representative NA. The adsorption kinetics followed a pseudo-second-order model for the data (0.007 g min-1 mg-1), while the equilibrium data fitted the Sips model ( q m = 140.55 mg g-1). The process's thermodynamics indicated that the target NA's adsorption was spontaneous and exothermic. The localized sterical and energetic aspects were investigated through statistical physical modeling, which corroborated that the adsorption occurred indeed in monolayer, as suggested by the Sips model, but revealed the contribution of two energies per site ( n 1 ; n 2 ). The number of molecules adsorbed per site ( n ) was highly influenced by the temperature as n 1 decreased with increasing temperature and n 2 increased. These results were experimentally demonstrated within the pH range between 4 and 6, where both C6H11COO-(aq.) and C6H11COOH(aq.) species coexisted and were adsorbed by different energy sites. The polymer produced was naturally porous and amorphous, with a low surface area of 20 to 30 m2 g-1 that presented more energetically accessible sites than other adsorbents with much higher surface areas. Thus, this study shows that the relation between surface area and high adsorption efficiency depends on the compatibility between the energetic states of the receptor sites, the speciation of the adsorbate molecules, and the temperature range studied.

A sensitive bioanalytical ultra-high-performance liquid chromatography-tandem mass spectrometry method for the simultaneous quantitation of lactone and carboxylate forms of topotecan in plasma and vitreous.

Topotecan (TPT) is used in the treatment of retinoblastoma, the most common malignant intraocular tumor in children. TPT undergoes pH-dependent hydrolysis of the lactone ring to the ring-opened carboxylate form, with the lactone form showing antitumor activity. A selective, and highly sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry method was developed for the determination of both forms of TPT in one mobile phase composition in plasma and vitreous humor matrices. The method showed an excellent linear range of 0.375-120 ng/mL for the lactone. For the carboxylate, the linear range was from 0.75 to 120 ng/mL. The matrix effect and the recovery for the lactone ranged from 98.5% to 106.0% in both matrices, for the carboxylate form, it ranged from 94.9% to 101.2%. The dynamics of the transition between TPT lactone and TPT carboxylate were evaluated at different pH environments. The stability of TPT forms was assessed in plasma and vitreous humor at 8 and 37°C and a very fast conversion of lactone to carboxylate form occurred at 37°C in both matrices. The method developed facilitates the investigation of TPT pharmacodynamics and the release kinetics in the development of the innovative local drug delivery systems.

Oxidative Carboxylation of Lignin: Exploring Reactivity of Different Lignin Types.

The increased interest in the utilization of lignin in biobased applications is evident from the rise in lignin valorization studies. The present study explores the responsiveness of lignin toward oxidative valorization using acetic acid and hydrogen peroxide. The pristine lignins and their oxidized equivalents were analyzed comprehensively using NMR and SEC. The study revealed ring opening of phenolic rings yielding muconic acid- and ester-end groups and side-chain oxidations of the benzylic hydroxyls. Syringyl units were more responsive to these reactions than guaiacyl units. The high selectivity of the reaction yielded oligomeric oxidation products with a narrower dispersity than pristine lignins. Mild alkaline hydrolysis of methyl esters enhanced the carboxylic acid content of oxidized lignin, presenting the potential to adjust the carboxylic acid content of lignin. While oxidation reactions in lignin valorization are well documented, this study showed the feasibility of employing optimized oxidation conditions to engineer tailored lignin-based material precursors.

Design, Synthesis, and Biological Evaluation of 1,2,4-Oxadiazole Derivatives Containing an Aryl Carboxylic Acid Moiety as Potent Sarbecovirus Papain-like Protease Inhibitors.

Papain-like protease (PLpro) is a promising therapeutic target for its pivotal role in the life cycle of SARS-CoV-2. A series of 1,2,4-oxadiazole derivatives was designed and synthesized via a ring formation strategy based on SARS-CoV-2 PLpro-GRL0617 complex structure. Systematic structure-activity relationship studies revealed that introducing oxadiazole and aryl carboxylic acid moieties to GRL0617 enhanced the enzymatic inhibition activity, affinity, and deubiquitination capacity toward PLpro. 1,2,4-Oxadiazole compounds 13f and 26r, which had PLpro inhibition activity (IC50 = 1.8 and 1.0 µM) and antiviral activity against SARS-CoV-2 (EC50 = 5.4 and 4.3 µM), exhibited good metabolic stability (t1/2 > 93.2 min) and higher plasma exposure (AUC0-t = 17,380.08 and 24,289.76 ng·h/mL) in mice. Especially, compound 26r with moderate oral bioavailability of 39.1% and potent antiviral activity is worthy of further studies in vivo. Our findings provide a new insight for the discovery of antiviral agents targeting PLpro.

Asymmetric ionic bond shielding encountering with carboxylate capturing metal ions for enhancing the flame retardant durability of regenerated cellulose fibers.

Enhancing the flame retardancy and durability of cellulose fibers, particularly environmentally friendly regenerated cellulose fibers types like Lyocell fibers, is essential for advancing their broader application. This study introduced a novel approach to address this challenge. Cationic-modified Lyocell fibers (Lyocell@CAT) were prepared by introducing quaternary ammonium structures into the molecular chain of Lyocell fibers. Simultaneously, a flame retardant, APA, containing -COO-NH4+ and -P=O(O-NH4+)2 groups was synthesized. APA was then covalently bonded to Lyocell@CAT to prepare Lyocell@CAT@APA. Even after undergoing 30 laundering cycles (LCs), Lyocell@CAT@APA maintained a LOI value of 37.2 %, exhibiting outstanding flame retardant durability. The quaternary ammonium structure within Lyocell@CAT@APA formed asymmetric ionic bonds with the phosphate and carboxylate groups in APA, effectively shielding the binding of Na+ ions with phosphate groups during laundering, thereby enhancing the durability. Additionally, the consumption of Na+ ions by carboxylate groups further prevented their binding to phosphate groups, which contributed to enhance the durability properties. Flame retardant mechanism analysis revealed that both gas and condensed phase synergistically endowed excellent flame retardancy to Lyocell fibers. Overall, this innovative strategy presented a promising prospect for developing bio-safe, durable, and flame retardant cellulose textiles.

Thermal oxidation mechanism of palmitic aicd.

The oxidation and degradation of fats lead to a decrease in the nutritional value of food and pose safety concerns. Saturated fatty acids also hold a significant position in the field of lipid oxidation. In this study, the oxidation products of methyl palmitate were investigated by using gas chromatography mass spectrometry (GC-MS). Seven monohydroperoxides and 72 secondary oxidation products were detected. Combined with density functional theory (DFT) calculations, the formation mechanisms of oxidation products can be summarized into four stages. The initial stage involved the formation of monohydroperoxides and alkanes, followed by the subsequent stage involving methyl x-oxo(hydroxy)hexadecanoates. The third stage involved the formation of methyl ketones, carboxylic acids, and aldehydes, while the final stage involved lactones. Meanwhile, methyl ketones were the most abundant oxidation product, approximately 25 times more abundant than aldehydes; the calculated results agreed well with the experimental results. The establishment of a comprehensive thermal oxidation mechanism for palmitic acid provided a new foundation for future lipid oxidation analyses.

Thiacalixarene Carboxylic Acid Derivatives as Inhibitors of Lysozyme Fibrillation.

Amyloid fibroproliferation leads to organ damage and is associated with a number of neurodegenerative diseases affecting populations worldwide. There are several ways to protect against fibril formation, including inhibition. A variety of organic compounds based on molecular recognition of amino acids within the protein have been proposed for the design of such inhibitors. However, the role of macrocyclic compounds, i.e., thiacalix[4]arenes, in inhibiting fibrillation is still almost unknown. In the present work, the use of water-soluble thiacalix[4]arene derivatives for the inhibition of hen egg-white lysozyme (HEWL) amyloid fibrillation is proposed for the first time. The binding of HEWL by the synthesized thiacalix[4]arenes (logKa = 5.05-5.13, 1:1 stoichiometry) leads to the formation of stable supramolecular systems capable of stabilizing the protein structure and protecting against fibrillation by 29-45%. The macrocycle conformation has little effect on protein binding strength, and the native HEWL secondary structure does not change via interaction. The synthesized compounds are non-toxic to the A549 cell line in the range of 0.5-250 µg/mL. The results obtained may be useful for further investigation of the anti-amyloidogenic role of thiacalix[4]arenes, and also open up future prospects for the creation of new ways to prevent neurodegenerative diseases.

Comprehensive investigation of coffee acidity on eight different brewing methods through chemical analyses, sensory evaluation and statistical elaboration.

Even if the acids composition and their role in coffee still need to be clarified, acidity is one of the main sought-after features in coffee and it is becoming one of the main quality markers. Hence, the aim of this paper was to evaluate the main parameters influencing coffee acidity with a focus on carboxylic acids. To the best of our knowledge, this is the first study regarding filter coffee prepared from specialty and mainstream coffee, differently roasted and through eight diverse extraction methods. Coffee cup chemical composition in terms of organic and chlorogenic acids, caffein and physicochemical parameters were correlated with perceived sourness and mouthfeel to better understand the influence of extracted compounds on the final beverage acidity. Statistical tools revealed that a major impact of chlorogenic acids emerged in pH and titratable acidity, while the sensorial sourness appeared more correlated with organic acids concentration. Thus, these findings suggests that organic acids could be potential predictors of beverage perceived acidity.

Synthesis and anti-tumor activities of three newly designed organotin(IV) carboxylates complexes.

Three distinctive end group-containing organotin (IV) carboxylates complexes (YDCOOSn, CLCOOSn and BZCOOSn) were designed and synthesized. Together with theoretical calculations, a thorough examination was carried out to investigate the photophysical properties of these compounds. The cytotoxicity of the synthesized compounds was tested using normal cell line GES-1 and was assessed against four cancer cell lines (A549, Hela, H1299 and HepG2). The outcomes of the experiments demonstrated that these complexes had superior selectivity than cisplatin towards cancerous cells, particularly in the A549 cell line. BZCOOSn was selected as a candidate compound for additional research because it exhibited the lowest IC50 value and the most impressive inducing effect on cell death and G2/M phase arrest. Increased caspase-3 and -9 enzyme activity, a decline in mitochondrial membrane potential (MMP), characteristic nuclear apoptotic morphology, and an accumulation of intracellular reactive oxygen species (ROS) were seen in A549 exposed to BZCOOSn. These findings demonstrated that BZCOOSn exhibited strong cytotoxicity by triggering cell death in A549 via the mitochondrial route. Furthermore, using the scratch wound healing assay, it was discovered that BZCOOSn reduced the migration of A549 cancerous cells. These data all pointed to BZCOOSn as a possible candidate for more research and development as a chemotherapeutic drug.

Design, synthesis, and biological evaluation of 5-(1H-indol-5-yl)isoxazole-3-carboxylic acids as novel xanthine oxidase inhibitors.

Xanthine oxidase (XO) is a key enzyme for the production of uric acid in the human body. XO inhibitors (XOIs) are clinically used for the treatment of hyperuricemia and gout, as they can effectively inhibit the production of uric acid. Previous studies indicated that both indole and isoxazole derivatives have good inhibitory effects against XO. Here, we designed and synthesized a novel series of N-5-(1H-indol-5-yl)isoxazole-3-carboxylic acids according to bioisosteric replacement and hybridization strategies. Among the obtained target compounds, compound 6c showed the best inhibitory activity against XO with an IC50 value of 0.13 µM, which was 22-fold higher than that of the classical antigout drug allopurinol (IC50 = 2.93 µM). Structure-activity relationship analysis indicated that the hydrophobic group on the nitrogen atom of the indole ring is essential for the inhibitory potencies of target compounds against XO. Enzyme kinetic studies proved that compound 6c acted as a mixed-type XOI. Molecular docking studies showed that the target compound 6c could not only retain the key interactions similar to febuxostat at the XO binding site but also generate some new interactions, such as two hydrogen bonds between the oxygen atom of the isoxazole ring and the amino acid residues Ser876 and Thr1010. These results indicated that 5-(1H-indol-5-yl)isoxazole-3-carboxylic acid might be an efficacious scaffold for designing novel XOIs and compound 6c has the potential to be used as a lead for further the development of novel anti-gout candidates.

Coordinative Compounds Based on Unsaturated Carboxylate with Versatile Biological Applications.

This review presents an overview of the biological applications of coordinative compounds based on unsaturated carboxylates accompanied by other ligands, usually N-based heterocyclic species. The interest in these compounds arises from the valuable antimicrobial and antitumor activities evidenced by some species, as well as from their ability to generate metal-containing polymers suitable for various medical purposes. Therefore, we describe the recently discovered aspects related to the synthesis, structure, and biological activity of a wide range of unsaturated carboxylate-containing species and metal ions, originating mostly from 3d series. The unsaturated carboxylates encountered in coordinative compounds are acrylate, methacrylate, fumarate, maleate, cinnamate, ferulate, coumarate, and itaconate. Regarding the properties of the investigated compounds, it is worth mentioning the good ability of some to inhibit the development of resistant strains or microbial biofilms on inert surfaces or, even more, exert antitumor activity against resistant cells. The ability of some species to intercalate into DNA strands as well as to scavenge ROS species is also addressed.

Amino Functionality Enables Aqueous Synthesis of Carboxylic Acid-Based MOFs at Room Temperature by Biomimetic Crystallization.

Enzyme immobilization within metal-organic frameworks (MOFs) is a promising solution to avoid denaturation and thereby utilize the desirable properties of enzymes outside of their native environments. The biomimetic mineralization strategy employs biomacromolecules as nucleation agents to promote the crystallization of MOFs in water at room temperature, thus overcoming pore size limitations presented by traditional postassembly encapsulation. Most biomimetic crystallization studies reported to date have employed zeolitic imidazole frameworks (ZIFs). Herein, we expand the library of MOFs suitable for biomimetic mineralization to include zinc(II) MOFs incorporating functionalized terephthalic acid linkers and study the catalytic performance of the enzyme@MOFs. Amine functionalization of terephthalic acids is shown to accelerate the formation of crystalline MOFs enabling new enzyme@MOFs to be synthesized. The structure and morphology of the enzyme@MOFs were characterized by PXRD, FTIR, and SEM-EDX, and the catalytic potential was evaluated. Increasing the linker length while retaining the amino moiety gave rise to a family of linkers; however, MOFs generated with the 2,2'-aminoterephthalic acid linker displayed the best catalytic performance. Our data also illustrate that the pH of the reaction mixture affects the crystal structure of the MOF and that this structural transformation impacts the catalytic performance of the enzyme@MOF.

Sensitive surface plasmon resonance biosensor by optimized carboxylate functionalized carbon nanotubes/chitosan for amlodipine detecting.

The adoption of biophotonic sensing technologies holds significant promise for application in health care and biomedical industries in all aspects of human life. Then, this piece of writing employs the powerful effective medium theory and FDTD simulation to anticipate the most favorable state and plasmonic attributes of a magnificent nanocomposite, comprising carboxylate functionalized carbon nanotubes and chitosan (CS). Furthermore, it thoroughly explores the exhibited surface plasmon resonance behaviors of this composite versus the quantity of CS variation. Subsequently, enlightening simulations are conducted on the nanocomposite with a delicate layer and a modified golden structure integrating as a composite. The intricate simulations eventually unveil an optimal combination to pave the way for crafting an exceptional specific biosensor that far surpasses its counterpart as a mere Au thin layer in terms of excellence. The proposed biosensor demonstrated linear behavior across a wide range from 0.01 µM to 150 µM and achieved a detection limit of 10 nM, with a sensitivity of 134◦RIU-1.

Leveraging Hydrazide as Protection for Carboxylic Acid: Suppression of Aspartimide Formation during Fmoc Solid-Phase Peptide Synthesis.

Despite numerous optimizations in peptide synthesis, the formation of aspartimide remains a significant side reaction that needs to be addressed. Herein, we introduce an approach that utilizes hydrazide as a carboxylic-acid-protecting group to reduce the formation of aspartimide. The aspartic acid hydrazide effectively suppressed the formation of aspartimide, even under microwave conditions, and was readily converted to native aspartic acid using CuSO4 in an aqueous medium.