Aliphatic Acids Research Articles

Structure and biochemical characterization of an extradiol 3,4-dihydroxyphenylacetate 2,3-dioxygenase from Acinetobacter baumannii

3,4-Dihydroxyphenylacetate (DHPA) 2,3-dioxygenase (EC 1.13.11.15) from Acinetobacter baumannii (AbDHPAO) is an enzyme that catalyzes the 2,3-extradiol ring-cleavage of DHPA in the p-hydroxyphenylacetate (HPA) degradation pathway. While the biochemical reactions of various DHPAOs have been reported, only structures of DHPAO from Brevibacterium fuscum and their homologs are available. Here, we report the X-ray structure and biochemical characterization of an Fe2+-specific AbDHPAO that shares 12% sequence identity to the enzyme from B. fuscum. The 1.8 Å X-ray structure of apo-AbDHPAO was determined with four subunits per asymmetric unit, consistent with a homotetrameric structure. Interestingly, the αβ-sandwiched fold of the AbDHPAO subunit is different from the dual β-barrel-like motif of the well-characterized B. fuscum DHPAO structures; instead, it is similar to the structures of non-DHPA extradiol dioxygenases from Comamonas sp. and Sphingomonas paucimobilis. Similarly, these extradiol dioxygenases share the same chemistry owing to a conserved 2-His-1-carboxylate catalytic motif. Structure analysis and molecular docking suggested that the Fe2+ cofactor and substrate binding sites consist of the conserved residues His12, His57, and Glu238 forming a 2-His-1-carboxylate motif ligating to Fe2+ and DHPA bound with Fe2+ in an octahedral coordination. In addition to DHPA, AbDHPAO can also use other 3,4-dihydroxyphenylacetate derivatives with different aliphatic carboxylic acid substituents as substrates, albeit with low reactivity. Altogether, this report provides a better understanding of the structure and biochemical properties of AbDHPAO and its homologs, which is advancing further modification of DHPAO in future applications.

Introducing free carboxylic acid groups along polyester chains using dimethylolpropionic acid as diol component

While different biodegradable polyesters have already been developed as green alternatives in food packaging, replacing functional polymers as present for example in superabsorbers is more complex due to the lack of selectivity in industrial polyester production. In this work, the trifunctional dimethylolpropionic acid (DMPA) was shown to react selectively as a diol component choosing the right reaction partners, introducing free carboxylic acid groups along the polyester chain. The reaction behavior was thoroughly investigated using a multimethod approach including NMR spectroscopy, MALDI mass spectrometry, and HPLC-MS. While reaction with adipic acid and 1,4-cyclohexanedicarboxylic acid was successful, material properties were inferior due to glass transition temperatures of the resulting polymers below 20 °C. A significant increase of Tg values up to 50 °C was obtained by introducing the aromatic isophthalic acid which could however not be realized in a direct reaction. Instead, a precondensate of isophthalic acid and neopentyl glycol was synthesized followed by the simultaneous addition of DMPA and the (cyclo)aliphatic acids. This protocol and the detailed description of characterization methods allow further investigations of DMPA polyester systems which carry potential in the fields of drug delivery, hydrogels, and superabsorbers as well as coatings, dispersants, and waste water treatment.

Lewis Acid Catalyzed Multicomponent Reaction of Aliphatic Aldehydes, Ynamides, Carboxylic Acids, and Amines to Access β3-Acylamino Amides

AbstractAn atom-economical strategy for the synthesis of alkylated β3-acylamino amides via Lewis acid catalyzed one-pot multicomponent reaction of ynamides, carboxylic acids, and aromatic amines with aliphatic aldehydes is described. In addition to the synthetic utility and scalability, the method exhibits excellent substrate scope and functional-group tolerance. The products can easily be transformed into valuable building blocks, such as peptide chains.

Endogenous Enzyme-Activatable Spherical Nucleic Acids for Spatiotemporally Controlled Signal Amplification Molecular Imaging and Combinational Tumor Therapy.

Due to the adjustable hybridization activity, antinuclease digestion stability, and superior endocytosis, spherical nucleic acids (SNAs) have been actively developed as probes for molecular imaging and the development of noninvasive diagnosis and image-guided surgery. However, since highly expressed biomarkers in tumors are not negligible in normal tissues, an inevitable background signal and the inability to precisely release probes at the chosen region remain a challenge for SNAs. Herein, we proposed a rationally designed, endogenous enzyme-activatable functional SNA (Ep-SNA) for spatiotemporally controlled signal amplification molecular imaging and combinational tumor therapy. The self-assembled amphiphilic polymer micelles (SM-ASO), which were obtained by a simple and rapid copper-free strain-promoted azide-alkyne cycloaddition click reaction between dibenzocyclooctyne-modified antisense oligonucleotide and azide-containing aliphatic polymer polylactic acid, were introduced as the core elements of Ep-SNA. This Ep-SNA was then constructed by connecting two apurinic/apyrimidinic (AP) site-containing trailing DNA hairpins, which could occur via a hybridization chain reaction in the presence of low-abundance survivin mRNA to SM-ASO through complementary base pairing. Notably, the AP site-containing trailing DNA hairpins also empowered the SNA with the feasibility of drug delivery. Once this constructed intelligent Ep-SNA nanoprobe was specifically cleaved by the highly expressed cytoplasmic human apurinic/apyrimidinic endonuclease 1 in tumor cells, three key elements (trailing DNA hairpins, antisense oligonucleotide, and doxorubicin) could be released to enable subsequent high-sensitivity survivin mRNA imaging and combinational cancer therapy (gene silencing and chemotherapy). This strategy shows great application prospects of SNAs as a precise platform for the integration of disease diagnosis and treatment and can contribute to basic biomedical research.

Photoinduced Pyridine N‐oxides Catalyzed Carbon Radical Generation from Alkylboronic Acids

AbstractHerein we report a protocol for the generation of alkyl carbon radicals from alkylboronic acids wherein photoexcited 4‐nitropyridine N‐oxide biradical features a catalyst to promote the nucleo‐homolytic substitution of boronic acids. With a wide range of readily available aliphatic boronic acids, including methyl boronic acid, the developed catalytic system demonstrates broad applicability for alkylation, amination, and cyanation.

Synthesis of β,γ-Unsaturated Aliphatic Acids via Ligand-Enabled Dehydrogenation.

α,β-Dehydrogenation of aliphatic acids has been realized through both enolate and β-C-H metalation pathways. However, the synthesis of isolated β,γ-unsaturated aliphatic acids via dehydrogenation has not been achieved to date. Herein, we report the ligand-enabled β,γ-dehydrogenation of abundant and inexpensive free aliphatic acids, which provides a new synthetic disconnection as well as a versatile platform for the downstream functionalization of complex molecules at remote γ-sites. A variety of free aliphatic acids, including acyclic and cyclic systems with ring sizes from five-membered to macrocyclic, undergo efficient dehydrogenation. Notably, this protocol features good chemoselectivity in the presence of more accessible α-C-H bonds and excellent regioselectivity in fused bicyclic scaffolds. The utility of this protocol has been demonstrated by the late-stage functionalization of a series of bioactive terpene natural products at the γ-sites. Further functionalization of the β,γ-double bond allows for the installation of covalent warheads, including epoxides, aziridines, and β-lactones, into complex natural product scaffolds, which are valuable for targeted covalent drug discovery.

Exploring the Potential of Biomass Pyrolysis for Renewable and Sustainable Energy Production: A Comparative Study of Corn Cob, Vine Rod, and Sunflower

The paper investigates the potential of biomass pyrolysis as a sustainable and renewable energy solution. The study focuses on three biomass types: corn cob, vine rod, and sunflower, which are abundant agricultural residues with potential for biofuel production. The pyrolytic gas, oil, and char produced during pyrolysis at a heating rate of 10 °C/min were analyzed. At the pyrolysis temperature of 500 °C, the corn cob showed the smallest final residual mass of 24%, while the vine rod exhibited the largest mass loss of 40%. Gas analysis revealed the concentrations of CO2, CO, H2, and CH4 in the pyrolytic gas, indicating its energy potential. Sunflower presented the largest calorific value of the produced biogas, while corn cob was the lowest. The chemical composition of the bio-oils was determined, with aliphatic acids identified as the dominant compounds, suggesting their potential for biodiesel production. Fourier Transform–Infrared Spectroscopy (FT-IR) analysis of raw biomass and char products demonstrated varying extents of decomposition among the biomass samples. A multicriteria assessment approach was employed to evaluate the differences between the selected three biomass feedstock and determined that sunflower biomass ranked the highest among the three, although the overall difference was small, confirming the suitability of all three biomass samples for pyrolysis conversion to higher-value-added fuels.

Mitigation of hydrocarbon toxicity using bacterial consortium in microcosm environment for agrarian fecundity

Petroleum contamination in the soil has been well emphasized as a toxic and hazardous soil pollution contributing to a significant portion of soil infertility worldwide. In the present study, bacterial consortium CHM1 composed of 5 strains belonging to genera Klebsiella, Pantoea, and Enterobacter was evaluated for hydrocarbon degradation ability in the soil environment, as well as their performance in remediating ecotoxicity and phytotoxicity. Initially, the degradation efficiency (1.98%/day) in the soil environment was evaluated. Scanning Electron Microscopy combined with Energy Dispersive X-ray spectroscopy revealed an increase in nitrogen content by 24.98% and a decrease in carbon content by 22.76% implying an improvement in soil fertility. The Fourier Transform InfraRed spectroscopy and Gas Chromatographic analysis revealed significant depletion of aromatic, cyclic, long aliphatic, and complex acid and ester content of the test soil. Moreover, the quantitative PCR analysis exhibited the non-competitive coexistence of each component of the CHM1 consortium. Different enzymatic assays revealed elevated dehydrogenase and superoxide dismutase activity in the degradation system due to the introduction of CHM1 in the soil microcosm. Vibrio fischeri-assisted ecotoxicity analysis had established the potential of CHM1 to efficiently minimize the ecotoxicity of hydrocarbon contamination. The phytotoxicity analysis was performed using four different plant models viz. Chickpeas (Cicer arientinum), Coriander (Coriandrum sativum), Fenugreek (Trigonella foenum-graecum), and Spinach (Spinacia oleracea) exhibiting CHM1 amendment helped to restore plant germination and growth in hydrocarbon-contaminated soil system efficiently. The promising results from this study indicated the possible application of the bacterial consortium in hydrocarbon-contaminated land management and soil restoration for cultivation or other plantation purposes.

Sustainability and repeatedly recycled epoxy-based vitrimer electromagnetic shielding composite material

A series of electromagnetic interference (EMI) shielding composites composed of an epoxy-based vitrimer matrix and stainless-steel fabric was prepared in this study. The polymer matrix presents tunable mechanical properties and chemical recyclability through adjustment of the content ratio of soft aliphatic sebacic acid (SA) to rigid crosslinker 3-(carboxymethyl)cyclopentane-1,2,4-tricarboxylic acid (TCAA). All the recycled vitrimers exhibit strengths comparable to the original materials, suggesting that similar cross-linking structures were reformulated successfully. Furthermore, a noticeable enhancement in the mechanical strength is observed for the combination of matrix and stainless-steel fabric, indicating that the combination of vitrimer material and fabric is excellent. However, a certain extent of decreased mechanical abilities was observed for the composites after reclaiming, while no apparent differences are noted in the results between multiple recycling processes. This tendency may be attributed to the complex fabric structure, which allows a distinct distribution for the reclaimed matrix that is repolymerized by evaporating the solvent compared to the original polymer. In addition, the original and repeatedly recycled composites reveal comparable EMI shielding abilities of around 70 dB, demonstrating the potential for high performance when applied as EMI shielding materials.

Palladium(II)-Catalyzed Decarboxylative Difunctionalization of Alkynoic Acids To Access (E)-β-Sulfonylacrylamides and DFT Study.

A palladium(II)-catalyzed regio- and stereoselective difunctionalization of alkynoic acids has been achieved using sodium sulfinates and isocyanides to synthesize (E)-β-sulfonylacrylamides. The reaction proceeds via decarboxylative isocyanide addition, followed by sulfonylation. This three-component process works well with aromatic, heteroaromatic, and aliphatic alkynoic acids with good functional group tolerance and excellent regio- and stereoselectivity. DFT calculations were carried out to explain the reaction mechanism and the stereoselective formation of (E)-β-sulfonylacrylamides.

Organic acid profiles of Australian stingless bee honey samples determined by ion chromatography.

The aliphatic organic acid content in stingless bee honey (n=111) from five Australian stingless bee species (Tetragonula carbonaria, T. hockingsi, T. davenporti, Austroplebeia australis and A. cassiae) was examined, with honey sourced from both rural and urban sources. Analysis of the organic acids as their anions was achieved using ion chromatography with suppressed conductivity detection with quantitation using external standards. Gluconic acid was the predominant organic acid detected in all the stingless bee honeys, followed by acetic and lactic acids, with the latter dependent on the genera. One-way ANOVA and principal component analysis (PCA) confirmed distinctive differences between honeys by genera. Both gluconic acid and malic acid were significantly higher in A. australis honeys compared to T. hockingsi (P < 0.0001) and T. carbonaria (P < 0.0001). Acetic acid was significantly lower in A. australis honeys compared to T. carbonaria (P < 0.01) and T. davenporti (P < 0.01). Lactic acid was significantly higher in Tetragonula honey samples, with honeys of all 3 species of Tetragonula showing statistically significant differences to A. australis honey (P < 0.05). Tetragonula honeys varied in organic acid content according to honey botanical origin. Variation by species and habitat was assessed using chemometrics. This study provides the first extensive data to characterise this food and to help understand the contribution these organic acids make to the characteristic tangy taste and organoleptic properties of stingless bee honeys.

Lecithin Microemulsions as Drug Carriers

The paper describes examples of microemulsions based on a well-known biocompatible surfactant, lecithin, and the possibilities of their use as drug carriers. The main problem encountered when developing lecithin microemulsions is the search for suitable cosurfactants. Molecules with short alkyl chains (4–5 C atoms) and relatively large polar “head,” such as short-chain aliphatic alcohols, acids, and amines are most suitable as cosurfactants for the preparation of lecithin microemulsions. Therewith, high concentrations of the cosurfactants (the cosurfactant : lecithin weight ratio usually is 1 : 1) are necessary. Most often, ethanol, n-propanol, or n-butanol are used as cosurfactants for the preparation of lecithin microemulsions in various natural and synthetic oils. To replace toxic alcohols with less toxic components, other well-known surfactants may be added to lecithin microemulsions. They are, e.g., Brij 96V (poly(ethylene glycol) oleate), Tween 80 (polyoxyethylene-20-sorbitan monooleate), Tween 20 (polyoxyethylene-20-sorbitan monolaurate). Triton X-100 (tert-octylphenyl ether of poly(ethylene glycol)) or oleic acid. Composites based on lecithin microemulsions have been described as means for local anesthesia and delivery of vitamins, as well as agents with anti-inflammatory, antifungal, anticancer, and wound healing effects. The considered examples show the promise of the study and development of lecithin microemulsions as drug carriers.

Environmentally Friendly Amino Acid-Based Polishing Slurry with Reduced Galvanic Corrosion at Copper/Cobalt Interface for Advanced Cu Interconnect Applications

Chemical mechanical planarization (CMP) is an integral part in semiconductor processing including the back-end-of-line (BEOL) step. A goal of CMP is to uniformly polish the metal interconnects and the liner/barrier materials while minimizing CMP-related defects such as pitting, dissolution, and galvanic corrosion. A variety of azoles are used as corrosion inhibitors such as benzotriazole (BTA) to prevent corrosion defects during polishing. [1,2] These azoles work together with particles in the slurries to polish the overplated metal forming the interconnects. However, azoles are very poorly biodegradable during wastewater treatment and highly toxic to the nitrification process, which requires expensive wastewater treatment challenges.[3,4] Also, it is known that the use of BTA leads to contamination of Cu films by forming undesirable hydrophobic organic residues (e.g., BTA and Cu-BTA complexes),[5] making their removal very difficult during cleaning. To address these challenges aliphatic amino acids were examined as potential corrosion inhibitors to replace problematic azoles in CMP slurries.Three amino acids were considered in a model CMP slurry. These three were chosen for their unique functional groups: methionine, containing a sulfur group, glutamic acid, having an extra carboxylic acid group, and leucine, having a branched hydrocarbon chain. A representative polishing slurry with 35 nm colloidal silica abrasives, 1 wt% hydrogen peroxide as an oxidizer, 0.5wt% arginine as a complexing agent, at pH 8 was used. Three experimental aims were considered (1) corrosion characterization of the three amino acid and BTA electrolytes with linear sweep voltammetry; (2) comparison of the Co and Cu metal removal rate (MRR) in polishing experiments with a proto-type CMP polisher with 8” wafers, and (3) oxidation of the amino acids and BTA in a Fenton assisted electrooxidation reaction. Methionine was most effective in controlling the galvanic corrosion of the Cu-Co couple. The Co and Cu MRR decreased in the presence of three amino acids and showed comparable removal selectivity. The forced degradation of the amino acids under the Fenton-assisted electrooxidation confirmed that they were more readily degraded compared to BTA. Acknowledgments: This work was supported by the Semiconductor Research Corporation grant (Task 3100.001) under the Global Research Collaboration program. References Seo, J., A review on chemical and mechanical phenomena at the wafer interface during chemical mechanical planarization. Journal of Materials Research 2021, 1-23.C. Peethala, H. P. Amanapu, U. Lagudu, and S.V. Babu, J. Electrochem. Soc, 159(6), H582-H588, 2012.D.E. Speed, Chapter 11, Advances in chemical mechanical planarization (CMP) 2nd edition, Babu, S. V., Ed. 2021.G. Li et al. / Chemosphere 241 (2020) 1249932.Seo, J.; Vegi, S. S. R. K. H.; Babu, S.V. ECS Journal of Solid State Science and Technology 2019, 8 (8), P379–P387.

Impact of critical point restriction on the calculation of surface tension of organic acids using group contribution models

This manuscript reports the calculation of surface tension of organic acids using new group contribution models. These models were obtained from the Jasper equation and the van der Waals principle of corresponding states. A special analysis was performed to determine the impact of incorporating the critical point restriction on the performance of tested group contribution models. This restriction was incorporated via a penalty term on the objective function used in the group contribution determination, and using the reduced temperature as the input model variable. A total of 885 experimental surface tension data points for 78 organic acids (including aliphatic, aromatic, dicarboxylic, and polyfunctional acids) were used to compare the performance of these group contribution models. The results showed that tested models calculated the surface tension of polyfunctional and aliphatic organic acids with modeling errors lower than 5%. However, the calculation of surface tension of aromatic and dicarboxylic acids was challenging for all tested models. The incorporation of critical point restriction of surface tension as a penalty term in the data processing stage did not improve the performance of tested group contribution models. Group contribution models that used the reduced temperature as an input variable showed the best performance for the calculation of the surface tension of these organic compounds.

Investigation Of the Composition of The Veterinary Preparation Trametin Plus

For the prevention and treatment of associated gastrointestinal and respiratory diseases in young farm animals, a new veterinary drug Trametin Plus is proposed, obtained on the basis of xylographic fungi using biotechnology methods. The properties of biological products obtained on the basis of microorganisms and fungi depend on the biologically active substances that make up their composition. In the literature, there is scattered information about the features of lipogenesis and the composition of fatty acids synthesized by wood-destroying fungi. The paper presents data on the study of the qualitative and quantitative composition of fatty acids, a qualitative analysis of volatile polar and non-polar organic compounds of the drug. It has been established that the total concentration of fatty acids is 70 µg/g of the preparation. Of these, 50.0% are free fatty acids, the esterified acids of which account for 50.0% of the total mass of fatty acids. Among the dominant non-polar volatile components of Trametin Plus, squalene can be noted. Organic aliphatic amino acids such as glycine, arginine, and β-alanine with a small molecular weight are presented as minor non-polar volatile components of Trametin plus. The analysis data confirm the multicomponent nature of the drug, which determines its various biological properties, namely, antibacterial, antiviral, antioxidant and immunostimulant activity, which determines the high therapeutic and prophylactic efficacy of the veterinary drug Trametin Plus.

Palladium-Catalyzed Aerobic Oxidative Spirocyclization of Alkyl Amides with Maleimides via β-C(sp3)-H Activation.

An efficient method for the synthesis of bicyclic spirodiamine molecules via β-C(sp3)-H bond activation of aliphatic amides, followed by cyclization with maleimides, has been developed. The reaction proceeds through an amide-directed β-C(sp3)-H bond activation of alkyl amides and subsequent cyclization with maleimides. The methodology is highly compatible with a wide variety of maleimides. Amides derived from biologically active aliphatic and fatty acids were also found to be highly compatible with the protocol. A palladacycle was synthesized and found to be the active intermediate in this reaction. A plausible reaction mechanism was also proposed to account for this spirocyclization.

Fabrication of Enzyme-Responsive Prodrug Self-Assembly Based on Fluazinam for Reducing Toxicity to Aquatic Organisms.

Prodrug-based nanodrug delivery systems were drug formulations by covalently conjugating drugs with inversely polar groups via a cleavable bond to self-assemble into nanoparticles for efficient drug delivery. To improve the utilization efficiency of fluazinam (FZN), enzyme-responsive prodrugs were prepared by conjugating FZN with different alkyl aliphatic acids through a nucleophilic substitution reaction and subsequently self-assembled into nanoparticles (FZNP NPs) without using any harmful adjuvant. The obtained FZNP NPs exhibited excellent efficacies against Sclerotinia sclerotiorum as a result of improved physicochemical properties, including low surface tension, high retention, and enhanced photostability. The LC50 values of FZNP NPs toward zebrafish were 3-8 times that of FZN, which illustrated that the FZNP NPs reduced the detriments of FZN to the aquatic organisms while retaining good biological activity. Therefore, prodrug self-assembly technology would offer a potential method for improving the utilization efficiency of pesticides and lowering the risks to the ecological environment.

Disturbances in plasma aliphatic and aromatic amino acids metabolomic profiles in Egyptian obese women

Disturbances in plasma aliphatic and aromatic amino acids metabolomic profiles in Egyptian obese women

Synthesis of 1,4‐Dicarbonyl Compounds via Visible‐Light‐Induced Decarboxylative Radical Cascade Reactions

AbstractWe herein report a method for the synthesis of 1,4‐dicarbonyl compounds using light‐activated electron donor‐acceptor (EDA) complexes. This multi‐component reaction involves the photoactivation of EDA complexes formed by carboxylic acid derivatives, triphenylphosphine, and sodium iodide, resulting in single‐electron reduction. The subsequent decarboxylation fragmentation leads to the formation of nucleophilic alkyl free radicals, which can undergo sequential radical coupling reactions with electron‐deficient and electron‐rich olefins. This method has been successfully applied to various aliphatic carboxylic acid derivatives, including tertiary, secondary, and primary ones, as well as multiple types of electron‐deficient olefins and enol silyl ethers. The entire process is conducted under mild conditions, indicating its potential for the synthesis of valuable synthetic compounds.

Chemistry of Dimer Acid Production from Fatty Acids and the Structure-Property Relationships of Polyamides Made from These Dimer Acids.

While there is abundant literature on using a wide range of biomaterials to make polymers for various adhesive applications, most researchers have generally overlooked developing new adhesives from commercially available bio-based dimerized fatty acids. Some of the literature on the chemistry taking place during the clay-catalyzed dimerization of unsaturated fatty acids is generally misleading in that the mechanisms are not consistent with the structures of these dimers and a by-product isostearic acid. A selective acid-catalyzed interlayer model is much more logical than the widely accepted model of clay-catalyzed Diels-Alder reactions. The resulting dimers have a variety of linkages limiting large crystal formation either as oligomeric amides or polyamides. These highly aliphatic fatty acid dimers are used to make a wide range of hot melt polyamide adhesives. The specific structures and amounts of the diacids and diamines and their relative ratios have a big effect on the bio-based polyamide mechanical properties, but analysis of the structure-property relationships has seldom been attempted, since the data are mainly in the patent literature. The diacids derived from plant oils are valuable for making polyamides because of their very high bio-based content and highly tunable properties.