Search Results (2,552)

Background/Objectives: Schistosomiasis, a parasitic disease caused by Schistosoma worms with freshwater snails as intermediate hosts, affects over 250 million people. The current control relies solely on praziquantel, which raises concerns on drug resistance and highlights the need for new therapeutic alternatives. Our bioprospection studies have focused on marine macroalgae as an unexplored source of antischistosomal metabolites with promising results. Guided by WHO recommendations to target both the parasite and its transmission vectors, this study aimed to investigate Ochtodes secundiramea to: (i) isolate active metabolites; (ii) evaluate the isolated compounds against adult worms and oviposition to identify leads for drug development; and (iii) perform an independent screening of their effects against the environmental transmission stages on cercariae and B. glabrata embryos. Methods: A dichloromethane extract of O. secundiramea was submitted to an NMR–biomonitored guided fractionation against Schistosoma mansoni adult worms. Active fractions were further purified through HPLC and characterized by ¹H and ¹³C NMR spectroscopy to identify the isolated compounds. Results: Three halogenated monoterpenes were isolated: ochtodene 1 (4-bromo-1,6,8-trichloro-2,3-ochtodene), ochtodene 2 (2-chloro-1,6,8-tribromo-3,8-ochtodene), and the novel natural product ochtodene 3 [2,6-dibromo-4-(2-chloroethylidene)-1,1dimethylcyclohexane]. Ochtodene 1 was the primary active metabolite against Schistosoma mansoni adult worms, with IC₅₀/96 h values of 47.2 and 46.1 µM for male and female worms respectively, and totally suppressed egg laying with 60 µM, while showing no toxicity toward human fibroblasts. Notably, all metabolites, including the novel ochtodene 3, caused 100% mortality in cercariae and embryos at low concentrations. Conclusions: The discovery of the novel ochtodene 3 and the identification of distinct leads for host treatment and transmission elimination position O. secundiramea as a promising source for integrated schistosomiasis control. Full article

A novel acidic polysaccharide (WDP) was purified from walnut dregs, and its structural characteristics and immunomodulatory function were investigated. WDP had a weight-average molecular weight (Mw) of 351.94 kDa and consisted mainly of rhamnose, arabinose, galactose, glucose, xylose, mannose, galacturonic acid, and glucuronic acid. Methylation and NMR analyses further demonstrated that the backbone of WDP comprised →4)-α-D-GalpA-(1→, →3,6)-β-D-Galp-(1→, →6)-β-D-Galp-(1→, →4)-β-D-Galp-(1→, and →4)-α-D-Glcp-(1→ residues, with branched chains consisting of terminal α-L-Araf-(1→ residues or α-L-Araf-(1→5)-α-L-Araf-(1→ fragments attached to the O-3 position of →3,6)-β-D-Galp-(1→ residues. In vitro assays indicated that WDP modulated immune responses in RAW264.7 cells by enhancing their phagocytosis; increasing NO release and the secretion of IL-1β, IL-6 and TNF-α; and activating the MAPK signaling pathway, suggesting its potential as an immunomodulatory agent. These results provide a scientific foundation for the development of walnut dregs-derived functional foods with immune-enhancing properties. Full article

Qualitative and quantitative analysis of complex mixtures and structure elucidation is generally impeded by the intrinsic complexity of the NMR spectra and the extensive signal overlap. The conventional approach to characterizing individual metabolites from complex crude extracts of natural products relies on multistep separation workflows employing diverse liquid chromatographic approaches and/or hyphenated techniques, which combine online integration of NMR with separation methods and other forms of spectroscopy. In recent decades, considerable efforts have been devoted to NMR applications in crude extracts without previous separation and isolation of the individual analytes. We present herein a critical overview of several NMR applications using chemical shift ranges of common organic functional groups, which can provide significant resolution advantages under specific experimental conditions. Particular emphasis is placed on: (i) characteristic chemical shift regions of strongly deshielded phenol OH groups, aldehyde CHO groups, hydroperoxide C-O-O-H groups and olefinic protons in conjugated double bonds; (ii) the advantages of using ¹³C chemical shift ranges through 2D ¹H-¹³C HSQC and HMBC experiments of strongly deshielded phenol OH groups, aldehyde CHO groups, hydroperoxide groups, conjugated double bonds, and deshielded aliphatic CH groups; (iii) selective 1D NMR-spin chromatography techniques (1D TOCSY, 1D NOE); (iv) multiple suppression of strong resonances for minor analyte identification and (v) band-selective excitation techniques for minor analyte identification and quantification. The complementary contributions of statistical heterospectroscopy and computational chemical shift prediction are also considered, together with a brief assessment of the NMR experimental parameters and performance characteristics. Full article

Phytochemical analysis of the tooth fungus Hydnellum aurantiacum resulted in the isolation of twenty-two compounds, including two new kavalactone derivatives—methylkavain (1) and aurapyrone (2); seven new p-terphenyl derivatives—ethylatromentin (3), 2-O-benzoylatromentin (4), aurantin (5), leucohydnelin (6), leucoaurantin (7), hydroxyleucoaurantiacin (8), benzoyltelephantin M (9); and thirteen known p-terphenyls—atromentin (10), aurantiacin (11), telephantin K (12), leucoatromentin (13), telephantin J (14), curtisian A (15), concrescenin B (16), telephantin L (17), dihydroaurantiacin dibenzoate (18), telephantin M (19), sarcodonin α (20), sarcodonin δ (21) and phellodonin (22). The structures were elucidated using spectroscopic methods (UV, NMR, HR-ESI-MS) along with comparison to literature data. All isolated substances, except 8 and 10, affected thrombin-induced human platelet activation at 90 μM: the seven compounds (9, 12, 16, 17, 20, 21, 22) potentiated it, while the remaining ones exhibited inhibitory activity with the strongest antiplatelet effects observed for 4, 5, and 7 (10.6 ± 4.0, 4.3 ± 3.2, 9.6 ± 2.9% of positive control, respectively). These and other p-terphenyl derivatives with antiplatelet activity identified in this study represent promising structures for further investigation into the mechanism of their action. Full article

Ni-doped amorphous Al₂O₃ catalysts were successfully prepared for the one-step reduction of nitrobenzene to azoxybenzene using NaBH₄ as hydrogen donors under mild conditions. The amorphous Ni₁Al₈₇O_x catalyst achieved a highly efficient azoxybenzene production rate of 1.89 mol·g-Ni⁻¹·h⁻¹, significantly outperforming its Ni/γ-Al₂O₃ counterpart. On the basis of the MAS NMR and XPS characterization results, the enhanced catalytic performance is associated with Ni incorporation during the preparation of amorphous Ni₁Al₈₇O_x, which introduces abundant unsaturated pentacoordinate Al species with oxygen vacancies and stabilizes Ni^δ+ sites against over-reduction. Notably, Ni₁Al₈₇O_x loaded on commercial ZSM-5 supports maintained an azoxybenzene yield of 9.02 mol·g-Ni⁻¹·h⁻¹, highlighting the strong potential for further scalable applications. Full article

Light-triggered hydrogel systems offer precise spatiotemporal control over drug release, yet most existing approaches require direct chemical conjugation of a photocleavable linker to the payload, which risks compromising bioactivity and limits applicability to structurally diverse molecules. Here, we report a gelatin–poly(ethylene glycol) (PEG) hybrid hydrogel crosslinked via strain-promoted azide–alkyne cycloaddition (SPAAC) click chemistry, in which an o-nitrobenzyl photocleavable (PC) linker is incorporated into the PEG crosslinker arm rather than conjugated to the drug. Acetylated gelatin–azide (AGA) was synthesized by sequential azide functionalization and amine capping of gelatin, and four-arm PEG-PC-DBCO (4armPEG-PC-DBCO) was prepared by coupling a PC DBCO-PEG4-NHS ester to four-arm PEG amine. Successful incorporation of the azide, DBCO, and o-nitrobenzyl moieties was confirmed by FT-IR spectroscopy, ¹H NMR spectroscopy, and UV-Vis spectrophotometry. Hydrogel formation under physiological conditions (PBS, 37 °C) without catalysts or initiators was verified by rheological frequency sweep analysis, which confirmed elastic-dominant behavior (G′ > G″). Upon irradiation at 365 nm, the crosslinker was cleaved, and rapid network dissolution was observed both macroscopically and by in situ time sweep rheology. This platform enables on-demand, UV-selective hydrogel degradation independently of payload identity, providing a versatile foundation for future controlled drug release applications and dynamic, on-demand degradable scaffolds for tissue engineering. Full article

To elucidate the molecular structural characteristics of weakly caking coal and the microscopic mechanism by which CO₂ inhibits coal–oxygen complexation, a weakly caking coal sample from the Dahaize coal mine in Shaanxi, China, was investigated using proximate and ultimate analyses, FTIR, XPS, and ¹³C NMR. On this basis, a representative coal macromolecular model was constructed and further analyzed using density functional theory (DFT) and grand canonical Monte Carlo (GCMC) simulations. The molecular formula of the representative weakly caking coal from the Dahaize mine (RNM) unit was determined as C₁₇₆H₁₅₆N₂O₁₉S₂. The aromatic carbon fraction was 65.41%, and the bridge carbon/peripheral carbon ratio was 0.25, indicating a certain degree of aromatic condensation but a limited content of highly fused aromatic structures. DFT calculations revealed that the reactive sites were mainly located around edge oxygen-containing functional groups and bridging structures, with a maximum Fukui index of approximately 0.024. Adsorption simulations showed that O₂ and CO₂ adsorption on RNM followed Langmuir-type behavior over 303.15–363.15 K: adsorption capacity increased with pressure and decreased with temperature. At 8000 kPa, the CO₂ uptake was approximately 1.6 times that of O₂. In the binary O₂-CO₂ system, CO₂ preferentially occupied pore surfaces and high-energy adsorption sites, reducing the local enrichment of O₂. These results provide a molecular-level explanation for the inhibition of coal–oxygen complexation by CO₂ through competitive adsorption, site shielding, and decreased oxidation probability at active sites. Full article

Two new anthraquinone derivatives, (±)-1′-O-methyl-6-chloroaverantin (1a and 1b) and 6-chloroaverythrin (2), and one new diphenyl ether 1-((E)-but-2-en-2-yl)-3,8-dihydroxy-6-((E)-4-hydroxybut-2-en-2-yl)-4,9-dimethyl-11H-dibenzo[b,e][1,4]dioxepin-11-one (3), along with six known compounds, were isolated from the fungus Aspergillus sp. SCSIO 41331 collected from the deep-sea sediment in the cold-seep area of the South China Sea. Elucidation of planar structures was achieved via 1D and 2D NMR and mass spectrometry, whereas stereochemistry was validated through optical rotation and NOE correlations, chiral phase HPLC analysis and NMR calculation. All compounds were assessed for antitumor activity, among which compound 4 displayed moderate antiproliferative activity against HT29 cells and suppressed colony expansion. Full article

Early-age strength development and carbon emissions represent specific operational constraints in underground cemented tailings backfill (CTB) operations. A pH and ionic pre-conditioning-assisted CO₂ mineralization process was evaluated for carbonate-rich cemented tailings backfill designed to improve early UCS while retaining measurable CO₂ uptake through systematic process control and optimization. Skarn-type tailings (CaO 16.74 wt%, total carbonates 34.7 wt%) were subjected to screening under nominal pH and ionic pre-conditioning treatments (4.0–11.5), CO₂ pressure (0–0.5 MPa), cement-to-tailings ratio (1:3–1:12), and slurry concentration (66–78%). Strength evolution (1–28 d), mineralization products were characterized using TGA as the primary CO₂-uptake method, with XRD used for semi-quantitative phase-trend assessment, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) with selected-area electron diffraction (SAED), X-ray computed tomography (CT), and nuclear magnetic resonance (NMR). Under optimal conditions (pH 8.5, 0.3 MPa CO₂ pressure, 48 h mineralization, 72–74% solids), mineralized specimens achieved 2-day uniaxial compressive strength equivalent to 1.47-times the 3-day control strength (p < 0.01), with peak net CO₂ sequestration of 37.1 g/kg. EBSD analysis of 347 grain boundaries and TEM-SAED examination of multiple foil sections supported the occurrence of syntaxial calcite overgrowth on primary carbonate debris as a major interfacial transition zone strengthening mechanism. Interconnected pore cluster volume decreased by 70.6%; Zn²⁺ and Pb²⁺ leaching decreased by 67.2% and 71.8%, respectively. A shrinking-core kinetics-Ryshkewitch model with pH-dependent correction functions predicted 3-day strength with acceptable accuracy for TW-A and TW-B, whereas TW-C showed a −27.3% deviation, identifying acidic and sulfate-rich wastewater as a boundary condition outside the reliable model domain. Field coring at −500 m depth provided pilot-scale evidence that a 23 mm mineralized shell was consistent with localized reduction of shallow exposed-face instability risk during the early free-standing period. Overall, the pH and ionic pre-conditioning-assisted CO₂ mineralization process is proposed as a laboratory-supported and field-informed screening framework for simultaneous early-strength enhancement and partial carbon sequestration in carbonate-rich cemented tailings systems. The resulting models and parameter guidance should be interpreted as preliminary design tools requiring further factorial optimization and long-term field validation before full site-specific deployment. Full article

To address the common drawbacks of polyamine-based CO₂ absorbents, such as high viscosity and precipitation at high CO₂ loading, a novel liquid–liquid biphasic absorbent composed of triethylenetetramine (TETA), 1-(2-aminoethyl)piperazine (AEP), N,N-dimethylacetamide (DMAC), and H₂O was developed in this study. By comprehensively evaluating CO₂ saturation loading, phase separation behavior, rheological properties of the CO₂-rich phase, precipitation suppression, and desorption–regeneration performance, the optimal absorbent formulation was identified as 20 wt% TETA + 10 wt% AEP + 40 wt% DMAC + 30 wt% H₂O. The optimized system enabled more than 98% of the CO₂ absorption products to be concentrated in the lower phase, which accounted for only 56% of the total liquid volume. Compared with the AEP-free TETA/DMAC/H₂O system, the optimized AEP-modified absorbent effectively eliminated precipitation and reduced the viscosity of the CO₂-rich phase to 62.3 mPa·s, while also improving the desorption behavior and cyclic stability of the system. In addition, ¹³C NMR analysis suggested that the salting-out effect is the main driving force for phase separation, with ionic products preferentially enriched in the aqueous phase to form the CO₂-rich lower phase. AEP contributes to viscosity reduction, precipitation suppression, and enhanced regeneration by weakening carbamate aggregation through steric hindrance and promoting bicarbonate formation. Full article

Triple-negative breast cancer (TNBC) is an aggressive subtype lacking effective targeted therapies, highlighting the need for new anticancer agents. Natural products remain a valuable source of bioactive compounds with diverse mechanisms of action. In this study, a pyrone glucoside, 7-hydroxymaltol-3-O-β-D-glucoside, was isolated from the methanolic leaf extract of Maerua angolensis and evaluated for its anticancer activity against TNBC cells. Structural elucidation was achieved using NMR and LC–MS analyses. Both the crude extract and the isolated compound exhibited dose-dependent cytotoxicity against MDA-MB-468 cells, with IC₅₀ values of 2.94 and 0.78 µg/mL, respectively, while showing reduced toxicity toward MCF10A normal cells. Mechanistic studies revealed induction of apoptosis, evidenced by activation of caspase-9 and caspase-7 and PARP cleavage. Confocal imaging further demonstrated lysosomal disruption and nuclear morphological alterations consistent with stress-associated cell death. Gene expression analysis indicated minimal involvement of the PI3K/AKT/mTOR pathway. Molecular docking showed favorable binding of the compound to AKT1, PARP-1, and caspase-7, suggesting a multi-target mode of action. ADMET analysis indicated low oral bioavailability but a favorable safety profile. These findings highlight the potential of this compound as a lead for TNBC therapy. Full article

An efficient catalyst for the reaction of ethanol–acetaldehyde into 1,3-butadiene (EATB) is prepared through the grafting of zirconia into a zeolite Beta lattice. The grafting is achieved through the dealumination of a zeolite framework by acid treatment followed by zirconia impregnation, leading to the substitution of aluminum in the zeolite framework by zirconia. The catalyst with zirconia grafted into the zeolite framework promotes desirable catalyst properties like high zirconium dispersion, stability, and the close proximity of Lewis acid, Bronsted acid, and medium basic sites. The phase, the coordination of zirconia, the location of the active center and the cooperative synergism were elucidated through various characterization techniques, including X-ray diffraction, Raman spectroscopy, N₂ adsorption, UV–vis spectroscopy, XPS, ²⁹Si MAS NMR, NH₃-TPD, Py-IR, CO-IR and CO₂-TPD. The catalytic results show that a suitable phase and content of zirconia were needed to improve the ethanol–acetaldehyde conversion, butadiene selectivity and catalyst stability. Among the catalysts, m+t-ZrO_x-Beta-H₂O-9020 (m = monoclinic, t = tetragonal ZrO₂ phase) achieved the best butadiene selectivity of 82–73% at the conversion of 100–66%, run over 200 h. The results allow us to propose a Lewis acid–medium basic pairing for the Si–O–Zr–O–Si group, where the adjacent Si-OH is the active center for reactions. Full article

We report a compact benchtop solid-state NMR platform that achieves 50 kHz magic-angle spinning (MAS) in a 1.4 T permanent magnet with an 18 mm bore, enabling high-speed MAS under extremely space-constrained conditions. The probe architecture leverages field–bore orthogonality for convenient magic-angle alignment and is demonstrated with miniaturized 1.8 mm rotors (≈5 mm length) at stable high-speed operation. As a demanding test case, we measure ⁷Li MAS NMR of the paramagnetic layered cathode oxide LiNi_0.5Mn_0.5O₂, where hyperfine interactions produce very large paramagnetic shifts spanning the several-thousand-ppm regime. Overall, the results establish a path toward portable, cost-effective high-MAS NMR in compact permanent-magnet geometries. Full article

Steroid glycosides constitute an important class of bioactive molecules, yet their selective synthesis remains challenging. Here, we established a screening platform for nucleotide sugar-dependent glycosyltransferases (GTs) coupled with sucrose synthase (SuSy) for in situ UDP-glucose regeneration, enabling cost-efficient steroid glucosylation. A library of GTs comprising literature-derived enzymes and newly mined archaeal and fungal candidates was constructed using sequence filtering, AlphaFold3 modeling, and docking-guided prioritization. The resulting panel was screened against 31 structurally diverse steroids (androgens, estrogens, pregnanes, and corticosteroids) using crude Escherichia coli lysates as catalysts and UPLC-DAD, LC-MS and NMR analytics. YjiC and OleD glycosyltransferases emerged as the most promiscuous biocatalysts, while Sbaic7OGT and SgUGT74AC1_M7 displayed greater selectivity toward estrogens and selected testosterone derivatives. Product assignment for representative reactions was validated using authenticated reference standards or NMR (1D/2D) analysis, confirming regioisomeric estradiol monoglucosides (3-O- and 17-O-), estrone 3-O-glucoside, and an unexpected product diversification for 17α-testosterone by endogenous E. coli enzyme, where the major product was identified as a 6′-O-acetylated glucoside. Finally, SuSy-coupled cascades were applied in semi-preparative scale and evaluated under optimized conditions and co-immobilization formats. Full article

For agricultural films, spectral matching, UV protection, and environmental durability are essential for efficient crop production. A self-cleaning silane-crosslinked red/blue dual-emission carbon dot/polyvinyl alcohol composite film (KH/RB-CQDs/PVA) was fabricated via a covalent anchoring strategy. RB-CQDs were synthesized by a two-step hydrothermal method using o-phenylenediamine: initial blue-emitting carbon cores formed, then phosphoric acid-assisted secondary treatment covalently bridged residual precursor-derived red fluorophores onto cores through pyrophosphate bonds, as evidenced by TEM, XPS, ³¹P NMR, HPLC-MS and DFT. This rigid bridging suppressed excessive core growth and energy transfer while spatially separating dual emission, endowing excellent photostability (>95% fluorescence retention after 50 min UV and 30 d storage). Subsequently, KH-560 was employed to construct a robust covalent crosslinked network anchoring RB-CQDs in PVA and forming rough Si-O-Si surface structures, confirmed by SEM and XPS. The resulting film exhibited 16.16% quantum yield, 291% tensile strength enhancement, 95% UV shielding, and <1% contaminant residue. Chlorophyll fluorescence kinetics, gas-exchange analyses, and photosynthetic response curves demonstrated that KH/RB-CQDs/PVA increased the potato net photosynthetic rate by 55.46% and tuber yield by 76% through synergistic optimization of photosystem II electron transport and RuBisCO-mediated carbon assimilation. This work provides a molecular design principle for high-performance intelligent agricultural films. Full article