Short-chain fatty acids (SCFAs) are major gut microbiota-derived metabolites, which can reshape the intestine and regulate gut immunity. The application of conventional GC methods has been hampered ...for quantifying low-concentrated SCFAs, such as in serum, saliva, and digesta of germ-free animals. Herein, we established a LC–MS method to quantify SCFAs after 5-(dimethylamino)-1-carbohydrazide-isoquinoline (DMAQ) derivatization. The DMAQ derivatization significantly enhanced the detection sensitivity and improved separation of SCFAs. 2-methylbutyric acid and 3-methylbutyric acid were separately quantitated. Moreover, the matrix effect was diminished using DMAQ-13C/15N-tagged SCFAs as internal standards. The established quantitation method was successfully applied in the analysis of plasma and cecum digesta collected from neonatal piglets, revealing that significant increases in biological SCFA contents in cecum digesta were closely related to the variation of gut microbial diversity. The established quantitation method is capable of sensitively and comprehensively quantifying SCFAs that may provide insights into underlying gut-microbiota functions.
Fourteen undescribed nitrogenous merosesquiterpenoids, purpurols A−D (1–4) and puraminones A−J (5–14), along with three known related compounds (15–17) were isolated from the sponge Pseudoceratina ...purpurea collected in the South China Sea. Their structures and absolute configurations were unambiguously elucidated by a combination of spectroscopic data, X-ray diffraction analysis, electronic circular dichroism calculations, and chemical derivatization. Purpurols A−D (1–4) incorporated nitrogenous heterocycles, compounds 1 and 2 feature an unusual benzothiazole ring, while 3 and 4 feature benzoxazole ring. Puraminones A−J (5–14) represent sesquiterpenoid aminoquinones with different amine and amino acid side chains at C-20. Additionally, twenty unreported sesquiterpenoid aminoquinone analogues were obtained through chemical derivatization. It is worth noting that all compounds are featured with unusual rearranged 4,9-friedodrimane subunit. In the bioassays, purpurols A and B showed weak anti-inflammation in zebrafish, as well as some compounds showed activities against tumor cells, therefore, preliminary structure–cytotoxicity relationships are also discussed.
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•Fourteen undescribed nitrogenous merosesquiterpenoids were reported.•Their structures were elucidated by NMR, ECD, chemical derivatization, and X-ray diffraction.•Compounds 1 and 2 showed weak anti-inflammation in zebrafish.•Compounds 5, 9, 10, and 14 showed moderate cytotoxicity against K562 cell lines.
A method for the direct functionalization of diamondoids has been developed using photoredox and H atom transfer catalysis. This C–H alkylation reaction has excellent chemoselectivity for the strong ...3° C–H bonds of adamantanes in polyfunctional molecules. In substrate competition reactions, a reversal in selectivity is observed for the new H-atom transfer catalyst reported here in comparison to five known photochemical systems. Derivatization of a broad scope of diamondoids and adamantane-containing drugs highlights the versatility and functional group tolerance of this C–H functionalization strategy.
Carboxylic acids (CAs) represent a large group of important molecules participating in various biologically significant processes. Analytical study of these compounds is typically performed by liquid ...chromatography (LC) combined with various types of detection. However, their analysis is often accompanied by a wide variety of problems depending on used separation system or detection method. The dominant ones are: i) poor chromatographic behavior of the CAs in reversed-phase LC; ii) absence of a chromophore (or fluorophore); iii) weak ionization in mass spectrometry (MS). To overcome these problems, targeted chemical modification, and derivatization, come into play. Therefore, derivatization still plays an important and, in many cases, irreplaceable role in sample preparation, and new derivatization methods of CAs are constantly being developed. The most commonly used type of reaction for CAs derivatization is amidation. In recent years, an increased interest in the isotopic labeling derivatization method has been observed. In this review, we comprehensively summarize the possibilities and actual trends in the derivatization of CAs that have been published over the past decade.
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•Liquid chromatography coupled with mass spectrometry is predominant combination.•Amidation is the most used type of derivatization reaction.•Chiral derivatization stagnates in this field.•Stable isotope labeling is favorably used in analysis of large number of analytes.•Development of greener derivatization reagents for carboxylic acids is needed.
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•Cooking oil fume (COF) quantification method was developed.•Triglycerides in COFs were derivatized via non-catalytic transesterification.•The yield of non-catalytic ...transesterification was 97.2 %, showing high reliability.•This analytical method contributes to indoor air quality control.
Cooking oil fumes (COFs), which are aerosols formed via the interaction of water and oil (triglycerides, TGs), contribute to the incidence of lung cancer. Control of indoor COF concentrations has not yet been established, as reliable methods for quantifying COFs have not been developed. This study aimed to quantify COFs based on the derivatization of TGs via a non-catalytic transesterification reaction. Our investigation into the thermolytic behaviors of oil confirmed that COFs generated at ≤ 200 °C primarily consisted of oil and water vapor. Alkali-catalyzed transesterification is commonly used for the derivatization of TGs. However, it is sensitive to impurities such as free fatty acids and water, leading to side reactions. Furthermore, this reaction requires additional purification steps to separate the catalyst and has long reaction times (≥120 min). In contrast, non-catalytic transesterification is not sensitive to impurities and can achieve a conversion yield of over 97 wt% within 1 min. The conversion yield of non-catalytic transesterification was higher than that of the alkali-catalyzed method, indicating that non-catalytic transesterification could be a more reliable method for quantifying COFs. Additionally, the concentration of COFs determined using non-catalytic derivatization was higher than that obtained using the conventional aerosol analysis method (PM gravimetric method). This approach addresses a critical gap in current practices, offering a valuable tool for assessing and regulating COF levels in indoor spaces. Consequently, this contributes to broader efforts aimed at mitigating potential adverse health effects associated with exposure to COFs.
Biologically active low-molecular-mass thiols, mainly including glutathione (GSH), cysteine (Cys), homocysteine (Hcy), and cysteinylglycine (Cys-Gly), are important physiological components in ...biological fluids, and their analytical methods have gained continuous attention over recent years. We developed and validated a novel HPLC method for the quantification of GSH, Cys, Hcy, and Cys-Gly in human plasma, urine, and saliva using 4-chloro-3,5-dinitrobenzotrifluoride as the derivatization reagent. Analyses were linear from 0.15 to 500 μM with the coefficient regression range of 0.9987–0.9994. Detection limits ranged from 0.04 to 0.08 μM (S/N = 3). The developed method was applied to quantification of four thiols in human biological fluids collected from five donors with the concentration range of 2.50–124.25 μM, 0–72.81 μM, and 0–4.25 μM for plasma, urine, and saliva, respectively. The present method seemed to be an attractive choice for the determination of thiols in plasma, urine, and saliva.
Herein, the surface-enhanced Raman scattering (SERS) platform was combined with an azo coupling reaction and an aluminum alloy covered with a hydrophobic layer of praseodymium oxide and stearic acid ...complexes for the detection of histamine. The praseodymium oxide on aluminum alloy was successfully synthesized by the rare-earth-salt-solution boiling bath method and modified by stearic acid. Its surface exhibits a water contact angle (WCA) of 125.0°. Through the azo derivatization reaction with 3-amino-5-mercapto-1,2,4-triazole (AMTA) diazonium salts, histamine can be converted into the derivatization product with higher Raman activity. The mixture of the derivatization product and β-cyclodextrin-modified Ag nanoparticles (β-CD-AgNPs) were dropped onto the surface of an aluminum alloy covered with a hydrophobic layer of praseodymium oxide and stearic acid complexes, and dried for SERS measurement. The intensity ratio between the SERS peaks at 1246 cm−1 and 1104 cm−1 (I1246/I1104) of the derivatization product was used for the quantification of histamine. Under the selected conditions, the limit of detection (LOD) and the limit of quantification (LOQ) for this method were 7.2 nM (S/N = 3) and 24 nM (S/N = 10), respectively. The relative standard deviation (RSD) of this method for the determination of 1 μM histamine was 6.1 % (n = 20). The method was also successfully used for the determination of histamine in fish samples with recoveries ranging from 92 % to 111 %. The present method is simple, sensitive, reliable, and may provide a new approach for preparing the composite hydrophobic layer that can enhance SERS signals through hydrophobic condensation effect. Meanwhile, it may have a promising future in the determination of small molecular compounds containing an imidazole ring.
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•Trace histamine was determined by SERS platform combined with an azo coupling reaction and a composite hydrophobic layer.•The SERS platform exhibited excellent SERS activity to histamine.•The SERS intensity ratio between the specific peaks was used for the quantification of histamine.•It was successfully used to determine histamine in fish with high sensitivity and selectivity.
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Nitrate (NO3−) is a widespread pollutant in the water environment. Due to its physicochemical properties, such as negative monovalent charge, traditional adsorption treatment ...processes have low selectivity for NO3− removal, resulting in low removal efficiency of NO3− by adsorbents in the presence of interfering ions. Therefore, to improve the adsorption selectivity and efficiency of NO3−. In this study, we used organosilicon quaternary modified derived nickel–iron layered double hydroxide (NiFe-MLDH/OQAS) for selective removal of NO3−. NiFe-MLDH/OQAS has a flowery globular structure, with interconnected nanosheets on the surface providing more adsorption sites for NO3−, which improves the adsorption rate and adsorption amount. What's more, the nitrate removal rate of NiFe-MLDH/OQAS only decreased by about 14.36% in the presence of the same concentration of interfering ions, and the maximum adsorption amount reached 61.05 mg/g, showing good selectivity and adsorption amount. Various characterization analyses indicate that the nitrate selectivity of NiFe-MLDH/OQAS is attributed to its unique layer spacing, as well as the abundant functional groups on the material surface. Finally, we demonstrated through experiments that NiFe-MLDH/OQAS has good cyclic regeneration ability and environmental safety. These findings demonstrate the great potential of NiFe-MLDH/OQAS for selective adsorption of NO3−.
An efficient method has been developed for the multiresidue and multiclass determination of 16 emerging contaminants (parabens, hormones, anti-inflammatory drugs, triclosan and bisphenol A) in water ...samples using rotating-disk sorptive extraction (RDSE) and gas chromatography coupled to mass spectrometry (GC-MS). Silylation of the compounds prior to GC-MS analysis was optimized using a factorial experimental design; the optimal derivatization conditions to maximize the response of the set of analytes included 70 μL of N-methyl-N-(trimethylsilyl)trifluoroacetamide at 80 °C for 35 min. RDSE was implemented using Oasis® HLB as a sorptive phase and an extraction time of 60 min.
The method was applied to Chilean environmental samples. In tap water, none of the analytes under study were detected. In the river and well waters, the concentrations of the four detected contaminants were below 0.38 μg L−1. In the effluent and influent of the wastewater treatment plant, the maximum concentrations of contaminants were 3.1 and 4.2 μg L−1, respectively.
The proposed analytical strategy suggests clear improvements with respect to other methods reported in the literature, considering not only the different steps involved in the analytical process (extraction, derivatization and chromatography) but also taking into account that this method involves the determination of different families of analytes with different physicochemical and structural properties.
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•Rotating disk sorptive extraction was implemented for first time as multi-residue and multi-class extraction method.•Experimental design was used to optimize the same derivatization reaction for all the analytes.•Separation/quantitation of 16 emerging contaminants was performed by GC-MS in a run of 25 min.•Emerging contaminants were determined in both wastewater and natural waters from Chile.
Despite recent advances in the treatment of cancer, the issue of therapy resistance remains one of the most significant challenges in the field. In this context, signaling molecules, such as ...cytokines have emerged as promising targets for drug discovery. Examples of cytokines include macrophage migration inhibitory factor (MIF) and its closely related analogue D-dopachrome tautomerase (D-DT). In this study we aim to develop a new chemical class of D-DT binders and subsequently create a dual-targeted inhibitor that can potentially trigger D-DT degradation via the Proteolysis Targeting Chimera (PROTAC) technology. Here we describe the synthesis of a novel library of 1,2,3-triazoles targeting D-DT. The most potent derivative 19c (IC50 of 0.5 ± 0.04 μM with high selectivity toward D-DT) was attached to a cereblon (CRBN) ligand through aliphatic amides, which were synthesized by a remarkably convenient and effective solvent-free reaction. Enzyme inhibition experiments led to the discovery of the compound 10d, which exhibited moderate inhibitory potency (IC50 of 5.9 ± 0.7 μM), but unfortunately demonstrated no activity in D-DT degradation experiments. In conclusion, this study offers valuable insight into the SAR of D-DT inhibition, paving the way for the development of novel molecules as tools to study D-DT functions in tumor proliferation and, ultimately, new therapeutics for cancer treatment.
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•Multifunctional biological targets require more sophisticated tools than merely downregulation or inhibition.•A first example of a non-competitive D-DT inhibitor with low micromolar activity has been synthesized.•A solvent-free ring-opening reaction of cyclic anhydrides was employed for the derivatization of pomalidomide.•A three-step click chemistry-based synthesis protocol was developed for the construction of dual inhibitors.•The synthesized D-DT-CRBN dual inhibitor was unable to act as a PROTAC.
