Carboxylic Compounds Research Articles

Genome analysis of a newly isolated Bacillus velezensis-YW01 for biodegrading acetaldehyde.

Acetaldehyde (AL), a primary carcinogen, not only pollutes the environment, but also endangers human health after drinking alcohol. Here a promising bacterial strain was successfully isolated from a white wine cellar pool in the province of Shandong, China, and identified as Bacillus velezensis-YW01 with 16S rDNA sequence. Using AL as sole carbon source, initial AL of 1g/L could be completely biodegraded by YW01 within 84h and the cell-free extracts of YW01 has also been detected to biodegrade the AL, which indicate that YW01 is a high-potential strain for the biodegradation of AL. The optimal culture conditions and the biodegradation of AL of YW01 are at pH 7.0 and 38°C, respectively. To further analyze the biodegradation mechanism of AL, the whole genome of YW01 was sequenced. Genes ORF1040, ORF1814 and ORF0127 were revealed in KEGG, which encode for acetaldehyde dehydrogenase. Furthermore, ORF0881 and ORF052 encode for ethanol dehydrogenase. This work provides valuable information for exploring metabolic pathway of converting ethanol to AL and subsequently converting AL to carboxylic acid compounds, which opened up potential pathways for the development of microbial catalyst against AL.

Characterization and acid treatment of silica and organics in evaporator blowdown wastewater arising from SAGD operations

The evaporator blowdown (EBD) wastewater from high-pressure steam generation for the steam-assisted gravity drainage (SAGD) bitumen extraction process contains elevated concentrations of dissolved inorganic and organic compounds, of which silica and organics pose challenges in its treatment and disposal. This study investigated treatment options for EBD before its disposal. Following detailed physical and chemical characterization of the EBD, we examined its acid treatment with HCl and H2SO4 at pHs ranging from 12 to 2. The acid treatment performance was evaluated in terms of silica and organic removal efficiencies along with the filtration rate and filtrate recovery. Both acids gave similar silica and organic removal efficiencies; however, the filtration performance following the HCl-treatment was better than the H2SO4-treatment. In practice, the acids would likely perform comparably with regard to silica removal and the final process selection would more likely be influenced by other factors such as storage, material compatibility, cost, and downstream or subsurface compatibility. The HCl-treatment was investigated further with both the EBD and prepared silica solutions for the silica removal efficiency and filtration performance. The experiments conducted at ∼20 °C demonstrated higher silica removal efficiencies at pHs 10 and 8, whereas higher organic removal efficiencies were obtained at pHs 4 and 2. The experiments conducted at ∼80 °C showed enhanced silica removal at pH = 8 and higher organic removal at pH = 2. The precipitated solids were characterized using XRD and ATR-FTIR spectroscopy to identify the minerals and functional groups. The XRD patterns demonstrated that the solids generated were amorphous. The ATR-FTIR spectra revealed the predominance of siloxane, silanol, carboxylate and carbonyl compounds. These results confirmed a substantial removal of silica and organic constituents from the EBD through the acid treatment process.

Sourdough Yeast Strains Exhibit Thermal Tolerance, High Fermentative Performance, and a Distinctive Aromatic Profile in Beer Wort.

The increasing popularity of home brewing and the fast evolution of craft beer companies have fuelled the interest in novel yeasts as the main actors diversifying the beer portfolio. Here, we have characterized the thermal tolerance and brewing-related features of two sourdough (SD) isolates of Saccharomyces cerevisiae, SDy01 and SDy02, at different temperatures, 20 and 37 °C, comparing them with commercial brew strains, AaB and kNB. The SD strains exhibited tolerance to the main brewing-related stress conditions and increased growth rates and lower lag phases than the reference beer strains at both temperatures. Consistent with this, SDy01 and SDy02 displayed higher fermentative activity in terms of sugar rate depletion and the release of metabolic by-products. Moreover, SDy01 and SDy02 brewing at 20 °C increased their total amount of volatile compounds (VOCs), in particular, their esters and carboxyl compounds, as compared to the reference AaB strain. In contrast, fermentation at 37 °C resulted in a drastic reduction in the number of VOCs in wort fermented with SD yeast, especially in its level of esters. In conclusion, our results stress the high fermentative performance of SD strains in beer wort and their ability to provide a complex and specific aromatic profile at a wide range of temperatures.

Genetic and chemical control of tuberculostearic acid production in Mycobacterium avium subspecies paratuberculosis.

Tuberculostearic acid (TBSA) is a fatty acid unique to mycobacteria and some corynebacteria and has been studied due to its diagnostic value, biofuel properties, and role in membrane dynamics. In this study, we demonstrate that TBSA production can be abrogated either by addition of pivalic acid to mycobacterial growth cultures or by a bfaA gene knockout encoding a flavin adenine dinucleotide (FAD)-binding oxidoreductase. Mycobacterium avium subspecies paratuberculosis (Map) growth and TBSA production were inhibited in 0.5-mg/mL pivalic acid-supplemented cultures, but higher concentrations were needed to have a similar effect in other mycobacteria, including Mycobacterium smegmatis. While Map C-type strains, isolated from cattle and other ruminants, will produce TBSA in the absence of pivalic acid, the S-type Map strains, typically isolated from sheep, do not produce TBSA in any condition. A SAM-dependent methyltransferase encoded by bfaB and FAD-binding oxidoreductase are both required in the two-step biosynthesis of TBSA. However, S-type strains contain a single-nucleotide polymorphism in the bfaA gene, rendering the oxidoreductase enzyme vestigial. This results in the production of an intermediate, termed 10-methylene stearate, which is detected only in S-type strains. Fatty acid methyl ester analysis of a C-type Map bfaA knockout revealed the loss of TBSA production, but the intermediate was present, similar to the S-type strains. Collectively, these results demonstrate the subtle biochemical differences between two primary genetic lineages of Map and other mycobacteria as well as explain the resulting phenotype at the genetic level. These data also suggest that TBSA should not be used as a diagnostic marker for Map.IMPORTANCEBranched-chain fatty acids are a predominant cell wall component among species belonging to the Mycobacterium genus. One of these is TBSA, which is a long-chain middle-branched fatty acid used as a diagnostic marker for Mycobacterium tuberculosis. This fatty acid is also an excellent biolubricant. Control of its production is important for industrial purposes as well as understanding the biology of mycobacteria. In this study, we discovered that a carboxylic acid compound termed pivalic acid inhibits TBSA production in mycobacteria. Furthermore, Map strains from two separate genetic lineages (C-type and S-type) showed differential production of TBSA. Cattle-type strains of Mycobacterium avium subspecies paratuberculosis produce TBSA, while the sheep-type strains do not. This important phenotypic difference is attributed to a single-nucleotide deletion in sheep-type strains of Map. This work sheds further light on the mechanism used by mycobacteria to produce tuberculostearic acid.

Preparation, characterization, antioxidant, and antifungal activity of phenyl/indolyl-acyl chitooligosaccharides

In this study, carboxylic acids compounds were grafted onto chitooligosaccharides to prepare seven phenyl/indolyl-acyl chitooligosaccharides derivatives. The structures of the derivatives were characterized by IR spectroscopy, 13C NMR and elemental analysis. Meanwhile, antioxidant activities in vitro of the novel derivatives were analyzed. Compared to COS and carboxylic acid, the derivatives showed higher scavenging capacity for superoxide anion and DPPH radicals, with scavenging rates of 59.39% and 94.86%, respectively. The hydroxyl radical scavenging ability of the derivatives was only 18.89%. The antifungal activities of chitooligosaccharide derivatives against Diaporthe batatas and Phytophthora capsici were studied by the growth rate method. Compared with chitooligosaccharide itself, derivatives were inhibited by 97.77% and 100%. The above results showed that chitooligosaccharide derivatives have good biocompatibility and can be used in food, agriculture and medicine.

Effect of Functional Groups in Lipid Molecules on the Stability of Nanostructured Lipid Carriers: Experimental and Computational Investigations.

Lipid nanoparticles have been used as drug carriers for decades. Many lipid types have been screened for both solid lipid nanoparticles and nanostructured lipid carriers (NLCs). Specifically, for NLCs that are composed of lipids in the solid form mixed with lipids in the liquid form, compatibility of lipid combination and phase behavior play a significant role in the NLC quality. In this study, stearic acid (STA) and cetyl palmitate (CTP) were used as solid lipids, and oleic acid (OLA), isopropyl palmitate (IPP), and caprylic/capric triglycerides were used as liquid lipids. NLCs were prepared at solid:liquid ratios of 50:50, 70:30, and 90:10, respectively. The characteristics and stability of the prepared NLCs were investigated. Laboratory results showed that the solid lipid had a greater influence on the particle size than the liquid lipid. Meanwhile, cetyl palmitate, an ester compound, provides higher NLC stability compared to stearic acid, a carboxylic acid compound. A MARTINI-based coarse-grained molecular dynamics simulation was used to simulate the lipid droplet in water. The distribution of lipid molecules in the droplet was characterized by the polar group density distribution. Different spatial arrangements of the lipid headgroup and lipid molecules, when CTP or STA was used as solid lipids, might contribute to the different stabilities of prepared NLCs. The understanding of mixed lipid systems via simulations will be a significant tool for screening the type of lipids for drug carriers and other pharmaceutical applications.

Deacetylation of Mannosylerythritol Lipids in Hydrophobic Natural Deep Eutectic Solvents

AbstractMannosylerythritol lipids (MELs) are a promising group of biosurfactants due to their high fermentation yield, selfassembly and biological activity. During fermentation by Pseudozyma aphidis, a mixture of MELs with different levels of acylation is formed, of which the fully deacetylated form is the most valuable. In order to reduce the environmental impact of deacetylation, an enzymatic process using natural deep eutectic solvents (NADES) has been developed. We tested the deacetylation of a purified MELs mixture with immobilized Candida antarctica lipase B enzyme and 2‐ethylhexanol as co‐substrate in 140 h reactions with different NADES. We identified hydrophobic NADES systems with similar yields and kinetics as in pure 2‐ethylhexanol solvent. Our results indicate that deacetylation of MELs mixtures in NADES as a solvent is possible with yields comparable to pure co‐substrate and that hydrophobic NADES without carboxylic acid compounds facilitate the reaction to the greatest extent.

Design, synthesis and antibacterial activity of novel 7H-thiazolo[3,2-b]-1,2,4-triazin-7-one derivatives

Based on the observed biological activity of 1,2,4-triazin-5-one derivatives and their cyclic analogues, a novel series of 7H-thiazolo[3,2-b]-1,2,4-triazin-7-one derivatives that contain ester moiety compounds 3a-3g, carboxylic acid moiety compounds 4a-4g and piperazine amide moiety compounds 5a-5k at position-3 of the thiazolotriazinone scaffold were synthesized. The intermolecular cyclization occurred regioselectively at N2-position of 1,2,4-triazine ring was characterized by X-ray single-crystal diffraction analysis. The in vitro biological activities of the target compounds were assayed against some bacterial strains. Compared with ciprofloxacin, compounds 3g and 4g exhibited more excellent antibacterial activity, especially the activity against Staphylococcus aureus and Escherichia coli, showing that the fluorine at the para position of the benzyl group would be the best choice. In addition, compounds 4e-4g with carboxylic acid moiety can enhance the antibacterial activity. Compounds 5g-5k containing bulky 1-(substituted phenyl)piperazine moiety were found with slightly less biological activity. Similar to ciprofloxacin, the docking result of target compounds with DNA topoisomerase II indicates the carboxyl group of the target compounds with carboxylic acid moiety has a crucial salt bridge interaction with Mg2+ in the protein.

AN UPDATE ON DOCKING ANALYSIS OF SOME PHARMACOLOGICAL ACTIVITY IN JAPANESE KNOTWEED LEAF COMPOUNDS

The proof of concept presents the results of molecular docking analysis in common Japanese knotweed leaf compounds compared to the four different proteases 4GQQ, 2B17, 2FW3 and 1ZB6 obtained from the Protein Data Bank. Several of these compounds show binding energy for the various proteases and according to our data compare favorably to a known antibacterial, anti-inflammatory, anti diabetic and antioxidant drugs. The advancement of improved docking techniques has also made it possible to more accurately predict the biological activity of substances. This paper provides compounds of a Japanese knotweed plant leaf to determine the result of gas chromatography-mass spectrometry to calculate binding energy compared to standardized drugs. The lowest amount of binding energy for good biological activity. The compound undecane had a higher negative binding energy than 2-hydroxyethyl cyclohexanecarboxylate. As we can see from the docking results, by comparing the values of the binding energies of the four proteins obtained from the protein data bank (PDB) (4GQQ, 2B17, 2FW3 and 1ZB6) we propose that the undecane molecule better is antibacterial, anti-inflammatory anti diabetic and antioxidant nature then cyclohexane carboxylic acid 2-hydroxyethyl ester compound. The DFT results HOMO-LUMO energy difference value (E=-0.44eV) indicated that the compounds more stability and reactivity. So energy difference minimum value of 2-hydroxyethyl clohexane carboxylate has good chemical stability and reactivity nature compared to other compound.

Ameliorating tannery sludge dewaterability by disintegration of extracellular biopolymers with FeCl3-MnSO4/oxalic acid/sodium percarbonate: Spectroscopic profiling of dissolved organic matter in sludge filtrate

Effectual sludge dewatering techniques are strongly desired by industrial wastewater treatment plants. In this work, we scrutinised the efficacy of various Fenton based complex mediated processes like ferric chloride (FeCl3)/oxalic acid (OA)/sodium percarbonate (SPC) (FOS), FS (without OA), manganese sulphate (MnSO4)/oxalic acid (OA)/sodium percarbonate (SPC) (MOS) and MS (without OA) for which capillary suction time (CST) was attained as follows: MS (204 s) < MOS (180 s) & FS (180 s) < FOS (174 s) at pH 3. This implied the role of chelating agent (OA) in improving sludge dewaterability by disintegrating Extracellular Polymeric Substances (EPS) and releasing converted free water from the sludge flocs. FTIR results of sludge samples revealed the higher release of aromaticity after treatment process. Presence of aromatic carboxylate compounds were confirmed by GC–MS analysis. A detailed inquisition on the dissolved organic matter (DOM) of filtrate samples using 3DEEM fluorescence methods like second derivative Accumulative Fluorescence Emission (AFE), Fluorescence Regional Integration (FRI) and UV–Visible spectroscopic method like multipeak Gaussian fitting were performed that signified Microbial Soluble Products.

Enhancing antibacterial properties by regulating valence configurations of copper: a focus on Cu-carboxyl chelates.

Optimizing the antibacterial effectiveness of copper ions while reducing environmental and cellular toxicity is essential for public health. A copper chelate, named PAI-Cu, is skillfully created using a specially designed carboxyl copolymer (a combination of acrylic and itaconic acids) with copper ions. PAI-Cu demonstrates a broad-spectrum antibacterial capability both in vitro and in vivo, without causing obvious cytotoxic effects. When compared to free copper ions, PAI-Cu displays markedly enhanced antibacterial potency, being about 35 times more effective against Escherichia coli and 16 times more effective against Staphylococcus aureus. Moreover, Gaussian and ab initio molecular dynamics (AIMD) analyses reveal that Cu+ ions can remain stable in the carboxyl compound's aqueous environment. Thus, the superior antibacterial performance of PAI-Cu largely stems from its modulation of copper ions between mono- and divalent states within the Cu-carboxyl chelates, especially via the carboxyl ligand. This modulation leads to the generation of reactive oxygen species (˙OH), which is pivotal in bacterial eradication. This research offers a cost-effective strategy for amplifying the antibacterial properties of Cu ions, paving new paths for utilizing copper ions in advanced antibacterial applications.

Photoinduced cerium-catalyzed C-H acylation of unactivated alkanes.

Ketones are ubiquitous motifs in the realm of pharmaceuticals and natural products. Traditional approaches to accessing these species involve the addition of metal reagents to carboxyl compounds under harsh conditions. Herein, we report a cerium-catalyzed acylation of unactivated C(sp3)-H bonds using bench-stable acyl azolium reagents under mild and operationally-friendly conditions. This reaction exhibits excellent generality, accommodating a wide range of feedstock chemicals such as cycloalkanes and acyclic compounds as well as facilitating the late-stage functionalization of pharmaceuticals. We demonstrate further applications of our strategy with a three-component radical relay reaction and an enantioselective N-heterocyclic carbene (NHC) and cerium dual-catalyzed reaction.

Investigation of the Molecular Structure and DFT Insights into (4-(4-Nitrophenyl)-9-(phenylsulfonyl)-9H-carbazole-2,3-diyl)bis(p-tolylmethanone)

Carboxylate molecules have been distinguished as the potential compound in the largely emergent chemical world of heterocyclic compounds shows likely pharmacological characteristics. The knowledge of a mixture of synthetic pathways and the different physicochemical parameters of such compounds describe the especial interest of medicinal chemists to produce combinatorial collection and carry out in-depth efforts in the search of lead molecules. Among the various group of compounds studied, carboxylate moieties stand out to be unique in features due to their biological, pharmacological and medicinal properties. Synthesis, crystal structure, conformation and density functional theory of (4-(4-Nitrophenyl)-9-(phenylsulfonyl)-9H-carbazole-2,3-diyl)bis(p-tolylmethanone) derivative have been investigated in detail. Carboxylate moiety is in planar conformation, C-H…O type of hydrogen bonds and van der Waals forces. Density functional theory was utilised to investigate the carboxylate derivative. Similar to co-crystal ligands, carboxylate compounds exhibited potent interactions with the target protein. The supramolecular properties were measured and validated using Hirshfeld surface studies.

EFFECT OF ETHANOL-WATER CONCENTRATION AS EXTRACTION SOLVENT ON ANTIOXIDANT ACTIVITY OF Acalypha indica

Acalypha indica is an abundant and obtainable wild weed plant in Indonesia. This is a possible opportunity to enhance its utility. The effect of free radicals is one of the factors that contribute to oxidative stress in the body, which can lead to cell damage and trigger various diseases. Plants rich in antioxidants can inhibit free radical reactions and protect the body from oxidative stress. In this study, we conducted the identification of major metabolite compounds using UHPLC-Q-Orbitrap HRMS from 70% ethanol extracts of Acalypha indica. We also performed phytochemical and antioxidant activity tests with various concentrations of ethanol-water solvents including water, 30%, 50%, 70% ethanol, and absolute ethanol to determine the optimal extraction conditions and the influence of solvent concentration on the antioxidant activity of Acalypha indica extract. The results of UHPLC-Q-Orbitrap HRMS identification showed that the 70% ethanol extract of Acalypha indica contains 10 major compounds suspected to correlate with its antioxidant activity. These include five flavonoids compounds (palasitrin, vitexin 2"-o-p-coumarate, isorhamnetin 3- (3",6"-di-p-coumarylglucoside), peucenin, and sulfuretin), two amino acid compounds (2-amino-3-carboxymuconic acid semialdehyde and N-Acetyl-L-phenylalanine), two carboxylic acid compound (citric acid and traumatic acid), and one phenolic compound (quinic acid). Phytochemical tests show positive results for flavonoids, tannins, alkaloids, and triterpenoids in each of water, 30%, 50%, 70% ethanol, and absolute ethanol extracts. The best antioxidant activity was obtained from the 70% ethanol extract with an IC50 value of 47.064 ppm, categorizing it as an extremely strong antioxidant.

Antitumor active trans‑platinum complexes through metabolic stability and enhanced cellular accumulation

Utilizing isoquinoline as a carrier ligand, we have evaluated the reactivity of selected trans‑platinum planar amine (TPA) carboxylate compounds by varying the leaving carboxylate group (acetate, hydroxyacetate, and lactate) in an effort to optimize the cytotoxic and metabolic efficiency. To measure the pharmacological properties of these compounds, a combination of systematic biophysical and biological studies were carried out mainly involving substitution reaction with NAM (N-acetyl-methionine), effects on DNA structural perturbation, cytotoxicity, cellular accumulation, metabolic stability, and cell cycle effects. TPA compounds showed minimal losses in cytotoxic efficacy and outperformed cisplatin after pre-incubation with serum, while displaying a distinct micromolar cytotoxic activity with minimal DNA binding and unaltered cell cycle. Monitoring the TPA compounds with NAM suggests the following trend for the reactivity: hydroxyacetate > lactate > acetate. The same trend was seen for the cytotoxicity in tumor cells and DNA binding, while the rate of drug inactivation/protein binding in cells was not significantly different among these leaving groups. Thus, our results show superior cellular efficacy of TPA compounds and distinct micromolar cytotoxic activities different than cisplatin. Moreover, we found the TPA compounds had prolonged survival and decreased tumor burden compared to the control mice in a relevant human ovarian cancer mouse model with A2780 cells expressing luciferase. Therefore, we propose that further optimization of the basic TPA structure can give further enhanced in vivo activity and may eventually be translated into the development of clinically relevant non-traditional platinum drugs.

Copper Complexes in Verdigris Painting Mixtures: An Electron Paramagnetic Resonance Characterization

Abstract Copper complexes, also called “copper soaps” when referred to carboxylate compounds, have become a concern in the conservation of historical artefacts. These complexes are suspected to play a significant role in degradation processes such as darkening and cracking of painting layers. Here we propose the Continuous Wave Electron Paramagnetic Resonance spectroscopy (CW-EPR) as a tool for the identification of these species. EPR spectroscopy is a micro-invasive and non-destructive technique that is highly sensitive to paramagnetic species, including radicals, crystal defects, and transition metal ions, e.g., Cu(II) and Fe(III). We have selected the verdigris (copper acetate) pigment combined with many organic binders, e.g., egg tempera and gum Arabic, as mock-up systems because of the known degradation tendency of the copper-based pigment. We would like to demonstrate that a precise analysis of the experimental spectra assisted with the calculus of the main magnetic quantities could lead to a good characterization of the copper complexes (or “soaps”).

Synthesis of pyrene and pyrrole-appended fluorescent turn-off sensor toward Cr(VI) detection: Chemical oxidative and electrochemical polymerization of carboxamide

A carboxylic amide compound containing pyrrole and pyrene groups, referred to as PP, was synthesized and characterized for its structural, optical, and electrochemical properties. Upon excitation with 320 nm light, PP displayed blue emission at 387 nm, which was found to be quenched due to chelate formation in the presence of Cr(VI). Conducted competition experiments involving chloride salts of Ag+, Al3+, Cd2+, Co2+, Cr3+, Fe3+, Hg2+, K+, Mn2+, Ni2+, Pb2+, Sn2+, and Zn2+ demonstrated the notable selectivity of compoundPP towards Cr(VI)ions. This selectivity was evidenced by a pronounced turn-off fluorescent effect, attributed to a chelation-enhanced quenching (CHEQ) mechanism by the formation of 1:2 chelation between Cr(VI) and the ligand PP. Moreover, addition of EDTA toPP– Cr(VI)chelation recovered the fluorescence offering receptorPPas a reversible sensor. The PP probe demonstrated remarkable selectivity in detection Cr(VI)ions among various metallic ions, displaying a limit of detection (LOD) value of 0.106 µM. Chemical oxidative and electropolymerization methods were employed to synthesize two distinct polymers, namely Poly(PP)-O and Poly(PP)-E, respectively. The electropolymerization of PP was carried out in 0.1 M TBAF6P serving as a supporting electrolyte solution, while oxidative polymerization was conducted in the presence of FeCl3. Mass average molecular weight of the oxidative polymerization product was 5200 Da, as determined by GPC analysis. Thermal characterization was performed via TG-DTA-DTG curves. The electropolymerization product of PP coated on the ITO surface was further characterized by SEM.

Molecular structure of dissolved organic carbon in a sandy soil receiving contrasting quality organic residues

Decomposing plant residues release plant-derived dissolved organic carbon (DOC) which can be transformed by microorganisms resulting in microbial-derived DOC (DOC biological function). The adsorbability of DOC to mineral surfaces, determined by DOC chemistry (DOC chemical function), can affect its vertical distribution down soil profiles (D). This study investigated the temporal characteristics (T) and functions (bioavailability, adsorbability) of DOC across the profile of a sandy soil by using chemically contrasting quality (Q) residues: 1) high-cellulose rice straw (RS), 2) nitrogen-rich groundnut stover (GN), 3) lignin-rich dipterocarp leaf litter (DP), and 4) medium-nitrogen and -lignin tamarind leaf litter (TM). Soil samples were collected at two depths (0–15 cm and 60–80 cm) two and eight weeks after residue application, and water-extractable DOC was determined. For the first time, the chemical structure of the extracted DOC was characterized using pyrolysis coupled with mid-infrared spectroscopy (Py-MIRS). The dominant functional groups found in all DOC samples were aromatic, carboxyl, and polysaccharide compounds. The interactive effects of Q, T, and D (soil depth) influenced DOC-polysaccharides, with the most pronounced effect observed in the RS treatment during the early stage, indicating that DOC-polysaccharides were mainly plant-derived. Evidence of partial adsorption of DOC-aromatics and DOC-carboxyls was found in topsoils. These high molecular weight-DOC functional groups may have displaced adsorbed polysaccharides, resulting in higher subsoil DOC-polysaccharides than topsoil, especially under DP and TM. During the later stage, topsoil DOC-polysaccharides were negatively related to microbial metabolic quotient (qCO2) (R2 = 0.938). This relationship led to our hypothesis that the dominant source of DOC-polysaccharides, particularly in the TM treatment, was of microbial origin. A novel discovery from this study is that the chemical quality of plant residues, which serve as the source of DOC, determines the origin of the polysaccharides in DOC. This origin transitioned from plant-derived to microbial-derived as decomposition progressed. Importantly, the presented findings were the first of its kind based on a field experiment.

Quantitative profiling of carboxylic compounds by gas chromatography-mass spectrometry for revealing biomarkers of diabetic kidney disease

Diabetic kidney disease (DKD), a common microvascular complication of diabetes, currently lacks specific diagnostic indicators and therapeutic targets, resulting in miss of early intervention. To profile metabolic conditions in complex and precious biological samples and screen potential biomarkers for DKD diagnosis and prognosis, a rapid, convenient and reliable quantification method for carboxyl compounds by gas chromatography-mass spectrometry (GC–MS) was established with isobutyl chloroformate derivatization. The derivatives were extracted with hexane, injected into GC–MS and quantified with selected ion monitoring mode. This method showed excellent linearity(R2 > 0.99), good recoveries (81.1%-115.5%), good repeatability (RSD < 20%) and sensitivity (LODs: 0.20–499.90 pg, LOQs: 2.00–1007.00 pg). Among the 37 carboxyl compounds analyzed, 12 metabolites in short-chain fatty acids (SCFAs) metabolism pathway and amino acid metabolism pathway were linked with DKD development and among them, 6 metabolites were associated with both development and prognosis of DKD in mice. In conclusion, a reliable, convenient and sensitive method based on isobutyl chloroformate derivatization and GC–MS analysis is established and successfully applied to quantify 37 carboxyl compounds in biological samples of mice and 12 potential biomarkers for DKD development and prognosis are screened.

Hydrophobic coating using sustainable sol-gel process doped with carboxylic acids to protect heritage copper artefacts

Metal corrosion and its mitigation using alkoxysilane based sol-gel coatings presenting specific properties are a matter of interest in many areas of applications, from industrial to cultural heritage materials. Thanks to their adhesive and coupling nature with different molecules and substrates, they show excellent results against aggressive environments. This study focuses on the protection of historical copper-based alloys. A tetramethyl orthosilicate-based (TMOS-based) sol-gel coating was doped with carboxylic acid compounds (heptanoic, octanoic and decanoic acids) recognized for their non-toxicity and their interesting corrosion inhibition properties on ancient corroded copper. The development of the coating and the basic understanding of the fundamental chemistry as well as the protection mechanism on the historical samples were studied. Contact angle measurements allowed to show that the resulting coating displayed a hydrophobic protection at the surface of the samples while its chemical composition was evaluated using thermogravimetric analysis, SEM-EDS and Raman spectroscopy. The porosity of the sol-gel matrix and the distribution of the acids in the porous silica network were then investigated by establishing nitrogen adsorption/desorption isotherms at liquid N2 temperature. Examination of the sample's cross-section by SEM-EDS showed that the TMOS-based coatings doped with carboxylic acids penetrated up to 60 % in depth in the corrosion layer of the ancient copper, while the Raman analyses showed that the acids formed organometallic complexes both at the surface and in the corrosion layer, leading to the protection of the metallic substrate against further corrosion.