Search Results (75)

Deep eutectic solvents (DESs) have emerged as prominent, environmentally benign substitutes for traditional solvents and catalysts in organic synthesis, notably in the synthesis of amines, pivotal structures in many industrial sectors. Their distinctive physicochemical attributes—including negligible volatility, exceptional thermal stability, and adjustable polarity—render them particularly advantageous for facilitating a broad spectrum of amination reactions. DESs can serve dually as reaction media and as intrinsic catalytic systems, accelerating reaction kinetics without necessitating supplementary catalysts or severe reaction conditions. They are especially efficacious in processes such as reductive amination, transamination, and multicomponent transformations, often affording superior yields and streamlining product isolation. The extensive hydrogen-bonding network intrinsic to DESs is believed to mediate crucial mechanistic steps, frequently obviating the requirement for external additives. Moreover, DESs are recyclable and exhibit compatibility with a diverse array of substrates, encompassing bio-derived and pharmaceutical intermediates. Full article

Sitagliptin, an important anti-diabetic drug, can be obtained using transaminase (TA) enzymes, which are known to be promising biocatalysts for the production of highly enantiopure amines under mild reaction conditions. In an industrial context, the use of immobilized enzymes can provide several advantages, such as the improved stability of the biocatalyst and easy product recovery. In this study, a new commercially available transaminase enzyme to produce sitagliptin was immobilized on inorganic and organic supports using two different approaches: adsorption and covalent bond formation. Among the inorganic media, non-functionalized silica gel was chosen for its stability and competitive cost. A range of commercially available resins with different functionalities have also been selected for their characteristics that can meet industrial standards. The immobilized biocatalysts were first tested in the transamination of acetophenone as a model substrate, which obtains, in most cases, higher conversions with respect to soluble enzymes. The best results in the enantioselective synthesis of sitagliptin were achieved with the sample immobilized on the epoxy- and octadecyl-functionalized methacrylic resin, which allowed the complete conversion of the corresponding ketone and high enantioselectivity (>99% ee). Moreover, the recycling of the supported enzyme could be performed in a continuous flow system without loss of activity for five consecutive runs. Full article

A series of differently substituted β-enaminones 2a,b, 4a–i, 8a–d, and 9–13, their BF₂-β-ketoiminate complexes 5a–d, and BF₂-β-diketonate complexes 6a–d were prepared as model substrates for photochemical transformations. The attempted photochemical transformations of enaminones 2, 4, 8 and BF₂-β-ketoiminate complexes 5 failed. On the other hand, irradiation of mixtures of BF₂-β-diketonate complexes 6a–d and cycloalkanes with UV-A light (365 nm) gave the corresponding De Mayo reaction products 7a–f in 9–30% yields. The photochemical ring-expansion of acetyl tetralone-derived BF₂-complex 6d gave novel diannulated cyclooctane derivatives 7e and 7f, which would be difficult to obtain using conventional cyclization methods. Full article

Leucine, isoleucine, and valine are collectively known as branched chain amino acids (BCAAs) and are often discussed in the same physiological and pathological situations. The two consecutive initial reactions of BCAA catabolism are catalyzed by the common enzymes referred to as branched chain aminotransferase (BCAT) and branched chain α-keto acid dehydrogenase (BCKDH). BCAT transfers the amino group of BCAAs to 2-ketoglutarate, which results in corresponding branched chain 2-keto acids (BCKAs) and glutamate. BCKDH performs an oxidative decarboxylation of BCKAs, which produces their coenzyme A-conjugates and NADH. BCAT2 in skeletal muscle dominantly catalyzes the transamination of BCAAs. Low BCAT activity in the liver reduces the metabolization of BCAAs, but the abundant presence of BCKDH promotes the metabolism of muscle-derived BCKAs, which leads to the production of glucose and ketone bodies. While mutations in the genes responsible for BCAA catabolism are involved in rare inherited disorders, an aberrant regulation of their enzymatic activities is associated with major metabolic disorders such as diabetes, cardiovascular disease, and cancer. Therefore, an understanding of the regulatory process of metabolic enzymes, as well as the functions of the BCAAs and their metabolites, make a significant contribution to our health. Full article

The first monomeric pyridoxal-5′-phosphate (PLP)-dependent transaminase from a marine, aromatic-compound-degrading, sulfate-reducing bacterium Desulfobacula toluolica Tol2, has been studied using structural, kinetic, and spectral methods. The monomeric organization of the transaminase was confirmed by both gel filtration and crystallography. The PLP-dependent transaminase is of the fold type IV and deaminates D-alanine and (R)-phenylethylamine in half-reactions. The enzyme shows high stereoselectivity; no deamination of L-amino acids and (S)-phenylethylamine is detected. Structural analysis and subsequent mutagenesis led to the conclusion that the monomeric architecture of the enzyme is the only one possible and sufficient for stereoselectivity and PLP binding, but not for the overall double-substrate transamination reaction and the stability of the holo form with the reduced cofactor—pyridoxamine-5′-phosphate. These results extend the structural university of the PLP fold type IV enzymes and demonstrate the need for deeper analysis of the sequence–structure–function relationships in the transaminases. Full article

Synthesis of 3-[((2-aminophenyl)amino)methylidene]furan-2(3H)-thiones was carried out by transamination reaction of 5-arylfuran-2(3H)-thiones under the influence of 1,2-phenylenediamine. A probable scheme of their formation was proposed. Configurational features of the obtained compounds were established on the basis of IR and NMR spectroscopy data, as well as using the NOESY 2D experiment. Full article

Background/Objectives: Warburg’s metabolic paradox illustrates that malignant cells require both glucose and oxygen to survive, even after converting glucose into lactate. It remains unclear whether sparing glucose from oxidation intersects with TCA cycle continuity and if this confers any metabolic advantage in proliferating cancers. This study seeks to understand the mechanistic basis of Warburg’s paradox and its overall implications for lymphomagenesis. Methods: Using metabolomics, we first examined the metabolomic profiles, glucose, and glutamine carbon labeling patterns in the metabolism during the cell cycle. We then investigated proliferation-specific metabolic features of malignant and nonmalignant cells. Finally, through bioinformatics and the identification of appropriate pharmacological targets, we established malignant-specific proliferative implications for the Warburg paradox associated with metabolic features in this study. Results: Our results indicate that pyruvate, lactate, and alanine levels surge during the S phase and are correlated with nucleotide synthesis. By using ¹³C_1,2-Glucose and ¹³C_6, ¹⁵N₂-Glutamine isotope tracers, we observed that the transamination of pyruvate to alanine is elevated in lymphoma and coincides with the entry of glutamine carbon into the TCA cycle. Finally, by using fludarabine as a strong inhibitor of lymphoma, we demonstrate that disrupting the transamination of pyruvate to alanine correlates with the simultaneous suppression of glucose-derived nucleotide biosynthesis and glutamine carbon entry into the TCA cycle. Conclusions: We conclude that the transamination of pyruvate to alanine intersects with reduced glucose oxidation and maintains the TCA cycle as a critical metabolic feature of Warburg’s paradox and lymphomagenesis. Full article

This study presents the development of a diglycidyl monomer containing two imine groups that can act as dynamic and reversible bonds. During the curing of the monomer with two different amine hardeners, we confirmed the formation of new imine groups due to the transamination reaction between the imine groups of the diepoxy monomer with the amine groups of the hardener. The effect of this structural change was observed in the stress relaxation behavior, resulting in the overlapping of two different relaxation modes. The analytical modelling was able to extract two distinct characteristic relaxation times using a double-element Maxwell model. A second characterization of the stress relaxation process by frequency sweep experiments was performed to corroborate the results obtained, confirming speedy stress relaxation. Acid-catalyzed hydrolysis was performed on the studied materials, demonstrating the complete degradation of the network. We finally confirmed that the synthesized diepoxy compound is suitable for preparing carbon-fiber-reinforced composite materials, demonstrating easy fiber impregnation, fast reshaping, and especially a total degradation of the polymer matrix that allows for the recovery of the carbon fibers in mild conditions. This epoxy–amine system is an excellent candidate for overcoming the traditional limits of thermosets in preparing fiber-reinforced composites. Full article

In the search for novel polymeric molecules that could be used as electroactive materials, seven novel polyenaminones were prepared in high yields by the transaminative polymerization of resorcinol-derived bis-enaminones with m- and p-phenylenediamine and with 2,5-diaminohydroquinone. The obtained polymers show very low solubility in organic solvents and absorb UV light and visible light at wavelengths below 500 nm. All the obtained polymeric products were tested for redox activity in a Li battery setup. The 2,5-diaminohydroquinone-derived compound showed the best redox activity, with a maximum capacity of 86 mAh/g and relatively good capacity retention, thus confirming the hydroquinone group as the primary redox-active group. Other potential redox-active groups, such as resorcinol and conjugated carbonyls, showed limited activity, while variations in the phenylene groups and the substitution of phenolic groups in the resorcinol residue did not impact the electrochemical activity of the polymers. Their electrochemical properties, together with their previously established chemical recyclability, make polyenaminones promising scaffolds for the development of materials for sustainable energy storage applications. Full article

We present a case of adult-onset systemic chronic active EBV disease (CAEBV) in a 40-year-old woman with chronic HBV hepatitis. Initial symptoms resembled a viral illness, progressing to recurrent fever, transaminitis, and anasarca. Investigations revealed high-level EBV viremia and an abnormal T-cell population in the liver and bone marrow, indicative of CAEBV. The liver biopsy showed CD3+ T-cells lacking TCRbeta and displaying dim/negative CD5, with elevated EBV-infected T-cells. Next-generation sequencing identified rare variants in CREBBP, SPEN, TP73, and PLCG2, suggesting potential contributions to disease pathogenesis. This case underscores the diagnostic challenges and management complexities of adult-onset CAEBV, particularly with underlying chronic HBV infection. Genomic profiling offers crucial insights into the molecular landscape of rare lymphoid malignancies, highlighting the importance of personalized treatment strategies. The distinct immunophenotypic features underscore the heterogeneity in EBV-associated T-cell LPDs, urging further research for optimized clinical management. Full article

Cannabis-based medicines (CBMs) could help reduce systemic inflammation in people with HIV (PWH). In a prospective, randomized pilot study we enrolled participants from August 2021–April 2022 with HIV, aged ≥18 and on antiretroviral therapy and randomly assigned them to cannabidiol (CBD) ± Δ9-tetrahydrocannabinol (THC) capsules for 12 weeks with the primary objective being to assess safety and tolerability. Here we report on timeliness to study initiation, enrolment, compliance and retention rates. The target sample size was not reached. Two hundred and five individuals were approached, and 10 consented and were randomized; the rest refused (reasons: cannabis-related stigma/discomfort; too many study visits/insufficient time; unwillingness to undergo a “washout period” for three weeks) or were not eligible. The age of those randomized was 58 years (IQR 55–62); 80% were male. Only three met all criteria (30% enrolment compliance); seven were enrolled with minor protocol deviations. Compliance was excellent (100%). Eight (80%) participants completed the study; two (20%) were withdrawn for safety reasons (transaminitis and aggravation of pre-existing anemia). Time to study initiation and recruitment were the most challenging aspects. Ongoing work is required to reduce stigma related to CBMs. Future studies should find a balance between the requirements for safety monitoring and frequency of study visits. Full article

LONP1 is the principal AAA+ unfoldase and bulk protease in the mitochondrial matrix, so its deletion causes embryonic lethality. The AAA+ unfoldase CLPX and the peptidase CLPP also act in the matrix, especially during stress periods, but their substrates are poorly defined. Mammalian CLPP deletion triggers infertility, deafness, growth retardation, and cGAS-STING-activated cytosolic innate immunity. CLPX mutations impair heme biosynthesis and heavy metal homeostasis. CLPP and CLPX are conserved from bacteria to humans, despite their secondary role in proteolysis. Based on recent proteomic–metabolomic evidence from knockout mice and patient cells, we propose that CLPP acts on phase-separated ribonucleoprotein granules and CLPX on multi-enzyme condensates as first-aid systems near the inner mitochondrial membrane. Trimming within assemblies, CLPP rescues stalled processes in mitoribosomes, mitochondrial RNA granules and nucleoids, and the D-foci-mediated degradation of toxic double-stranded mtRNA/mtDNA. Unfolding multi-enzyme condensates, CLPX maximizes PLP-dependent delta-transamination and rescues malformed nascent peptides. Overall, their actions occur in granules with multivalent or hydrophobic interactions, separated from the aqueous phase. Thus, the role of CLPXP in the matrix is compartment-selective, as other mitochondrial peptidases: MPPs at precursor import pores, m-AAA and i-AAA at either IMM face, PARL within the IMM, and OMA1/HTRA2 in the intermembrane space. Full article

Immunotherapy has emerged as a promising treatment approach in oncology, as it is specifically designed to boost the strength and accuracy of the immune system, allowing it to target tumor cells but spare non-tumor tissue. This treatment not only demonstrates potential for improved clinical outcomes but may also be associated with fewer adverse effects compared to traditional therapies. Despite its early success, the application of immunotherapy has largely been limited to adult cancer patients, with slow adoption noted in the treatment of pediatric cancer patients. Our objective is to demonstrate a single institution’s experience with immunotherapy in pediatric cancer patients and to discuss the use of these treatment modalities in this unique patient population. We performed a retrospective chart review and identified patients who received immune checkpoint inhibitors (ICIs) and/or underwent immunohistochemistry (IHC) testing for programmed death ligand 1 (PD-L1), quantification of tumor mutational burden (TMB), and classification of microsatellite instability (MSI) status. In total, we identified seven pediatric cancer patients who received therapy with ICIs. Four of these patients demonstrated positive PD-L1 expression, high TMB, and/or MSI-high status. These patients were treated with nivolumab alone or in combination with ipilimumab or brentuximab. The diagnoses included: multifocal epithelioid and spindle cell hemangioma (n = 1); metastatic melanoma (n = 2); histiocytic sarcoma (n = 1); rectal adenocarcinoma in the setting of constitutional mismatch repair deficiency syndrome (CMMRD) (n = 1); and Hodgkin lymphoma (n = 2). The patients received between four and nineteen cycles of immunotherapy. Immunotherapy-related adverse events included: mild allergic reaction; prodromal symptoms; anemia; neutropenia; transaminitis; endocrinopathies; and self-limiting neuritis. Of the seven patients, three are still being treated with immunotherapy (the patients with rectal adenocarcinoma, metastatic melanoma, and multifocal epithelioid and spindle cell hemangioma) with positive treatment responses observed on imaging, one is being treated with other modalities (the patient with Hodgkin lymphoma), two have achieved remission (the patients with metastatic melanoma and Hodgkin lymphoma), and one has relapsed (the patient with histiocytic sarcoma). The three patients who completed their immunotherapy regimens have been followed for 1 month, 4 months, and 10 months, respectively. This report of a single-institution experience with immunotherapy in pediatric cancer patients highlights the positive impact immunotherapy can have, especially when utilized to treat relapsed/refractory malignancies, as tumor regression or stabilization of disease burden was achieved in six of the patients described (CR = 2; PR = 4). Further research is needed to accurately identify pediatric oncology patients who could benefit from immunotherapy. Full article

Malpighian tubules (MTs) are arthropod excretory organs crucial for the osmoregulation, detoxification and excretion of xenobiotics and metabolic wastes, which include tryptophan degradation products along the kynurenine (KYN) pathway. Specifically, the toxic intermediate 3-hydroxy kynurenine (3-HK) is metabolized through transamination to xanthurenic acid or in the synthesis of ommochrome pigments. Early investigations in Drosophila larval fat bodies revealed an intracellular autofluorescence (AF) that depended on tryptophan administration. Subsequent observations documented AF changes in the MTs of Drosophila eye-color mutants genetically affecting the conversion of tryptophan to KYN or 3-HK and the intracellular availability of zinc ions. In the present study, the AF properties of the MTs in the Asian tiger mosquito, Aedes albopictus, were characterized in different stages of the insect’s life cycle, tryptophan-administered larvae and blood-fed adult females. Confocal imaging and microspectroscopy showed AF changes in the distribution of intracellular, brilliant granules and in the emission spectral shape and amplitude between the proximal and distal segments of MTs across the different samples. The findings suggest AF can serve as a promising marker for investigating the functional status of MTs in response to metabolic alterations, contributing to the use of MTs as a potential research model in biomedicine. Full article

The administration of a single dose of chitosan nanoparticles driving the expression of sterol regulatory element-binding protein 1a (SREBP1a) was recently associated with the enhanced conversion of carbohydrates into lipids. To address the effects of the long-lasting expression of SREBP1a on the growth and liver intermediary metabolism of carnivorous fish, chitosan-tripolyphosphate (TPP) nanoparticles complexed with a plasmid expressing the N terminal active domain of hamster SREBP1a (pSG5-SREBP1a) were injected intraperitoneally every 4 weeks (three doses in total) to gilthead sea bream (Sparus aurata) fed high-protein–low-carbohydrate and low-protein–high-carbohydrate diets. Following 70 days of treatment, chitosan-TPP-pSG5-SREBP1a nanoparticles led to the sustained upregulation of SREBP1a in the liver of S. aurata. Independently of the diet, SREBP1a overexpression significantly increased their weight gain, specific growth rate, and protein efficiency ratio but decreased their feed conversion ratio. In agreement with an improved conversion of dietary carbohydrates into lipids, SREBP1a expression increased serum triglycerides and cholesterol as well as hepatic glucose oxidation via glycolysis and the pentose phosphate pathway, while not affecting gluconeogenesis and transamination. Our findings support that the periodical administration of chitosan-TPP-DNA nanoparticles to overexpress SREBP1a in the liver enhanced the growth performance of S. aurata through a mechanism that enabled protein sparing by enhancing dietary carbohydrate metabolisation. Full article