Search Results (2,514)

Lonicera japonica Flos (LJF) is widely used in pharmaceuticals and functional foods, with its bioactive constituents significantly influenced by processing methods. This study characterized the dynamic changes in chemical components in LJF under different maceration and decoction durations. Using UPLC-Q-TOF-MS and molecular networking, a total of 260 metabolites were unambiguously identified or tentatively characterized, including 66 iridoids, 42 flavonoids and 49 phenolic acids. Among these, 11 phenolic acids and 3 flavonoids were absent in the macerated samples. Twenty-two representative compounds were quantified using calibration curves. Most secondary metabolites, particularly phenolic acids, exhibited lower levels in the macerated samples than the decocted samples (e.g., 5-O-caffeoylquinic acid: 65.67–106.41 μg/g during maceration vs. 32,783.05–55,754.68 μg/g during decoction). The decoction process significantly enhances the extraction of active constituents. Notably, certain iridoids (e.g., 7-O-methyl morroniside: 92.91–354.59 μg/g during maceration vs. 50.43–171.40 μg/g during decoction) were better preserved under maceration, highlighting its advantage for retaining heat-sensitive bioactive components. During the decoction process, 5-hydroxycinnamoylquinic acids tended to transform into 3- and 4-hydroxycinnamoylquinic acid isomers. Most di-hydroxycinnamoylquinic acids and flavonoids significantly decreased after 30 min. Nitrogen-containing seco-iridoids declined rapidly after 15 min. To balance extraction efficiency with the preservation of heat-sensitive bioactive components, a decoction time of 15–30 min is recommended. The study systematically elucidates the dynamic changes in bioactive components under two preparation methods, offering critical insights and a scientific foundation for the precision utilization of LJF in pharmaceutical and functional food industries. Full article

Synthetic cathinones are among the most frequently encountered classes of new psychoactive substances, and many occur as structural isomers sharing identical molecular formulas and highly similar mass-spectral features. Among them, substituted cathinones with the molecular formula C12H17NO (MW 191 Da) present particular analytical challenges because of their similar chromatographic behavior and overlapping ionization patterns. This study evaluated a combined EI-GC-MS and ESI-LC-MS/MS workflow, incorporating derivatization with trifluoroacetic anhydride (TFAA) and acetic anhydride (AA), for the differentiation of ten MW 191 Da isomers. TFAA-derivatized GC-MS enabled preliminary classification of the isomers, although several EMC and MEC analogs remained only partially resolved. AA derivatization improved the separation of unresolved isomers under slower oven temperature conditions, demonstrating the value of alternative acylation for enhancing chromatographic discrimination. LC-MS/MS provided complementary confirmation for several analytes, but some isomers remained difficult to distinguish because of shared product ions and peak fusion in mixed-standard analysis. Overall, this study establishes a practical analytical workflow for distinguishing MW 191 Da substituted cathinone isomers and highlights both the strengths and limitations of combining derivatization-based GC-MS with LC-MS/MS confirmation in routine forensic or clinical laboratories. Full article

Well-defined, small-molecule, platinum-centered coordination compounds are of continued interest in both basic and applied research, particularly in medicinal chemistry and pharmaceuticals (i.e., cisplatin). Organoplatinum(IV) complexes have been reported to exhibit substantial in vitro cytotoxicity across a range of cancer cell lines. Compared with coordinatively unsaturated platinum(II) species, electronically and coordinatively saturated platinum(IV) complexes are generally more inert, reducing undesirable side reactions in plasma and cellular environments and potentially improving their safety profiles as chemotherapeutic agents. In addition, the presence of organic ligands can enhance lipophilicity, facilitating passive diffusion across cell membranes. Here, we report the synthesis, structural characterization, and in vitro anticancer activity of a series of organoplatinum(IV) complexes of the general formula Pt(CH₃)₂I₂{n,n′-dimethyl-2,2′-bipyridine} (n,n′ = 4,4′; 5,5′; 6,6′). The 5,5′- and 6,6′-dimethyl isomers were characterized by single-crystal X-ray diffraction. All three dimethyl-substituted complexes, along with the parent compound, Pt(CH₃)₂I₂{2,2′-bipyridine}, were evaluated for cytotoxic activity against a panel of 60 human cancer cell lines. Whereas Pt(CH₃)₂I₂{2,2′-bipyridine} and the 4,4′- and 5,5′-dimethyl derivatives displayed limited cytotoxicity, the 6,6′-dimethyl isomer exhibited notable activity, particularly against the colon cancer cell line HCT-116 (LC₅₀ = 8.17 μM) and the ovarian cancer cell line OVCAR-3 (LC₅₀ = 7.34 μM). The enhanced cytotoxicity of the 6,6′-dimethyl derivative is attributed, at least in part, to the relatively facile dissociation of the 6,6′-dimethyl-2,2′-bipyridine ligand from the platinum(IV) center, suggesting that sterically induced ligand lability plays an important role in modulating biological activity in this particular compound, giving new structural activity impetus for potential drug molecules. Full article

Phenetole derivatives with dual ethoxy substituents exhibit rich conformational diversity and complex vibronic characteristics, making them important model compounds for understanding substituent effects on molecular structure and spectroscopy. In this work, we systematically investigated the stable rotamers, vibronic spectra, and cationic ground-state features of p-diethoxybenzene (PDEB) using resonance-enhanced multiphoton ionization (REMPI), UV-UV hole-burning (HB), and mass-analyzed threshold ionization (MATI) spectroscopies, combined with density functional theory (DFT) calculations. The ground-state potential energy surface (PES) of PDEB was calculated at the B3LYP/6-311++G(d,p) level, identifying eight rotamers with distinct statistical weights and relative energies. Hole-burning spectroscopy resolved two dominant rotamers (cis/up–up and trans/up–down) in the supersonic molecular beam, with their S₁←S₀ transition origins determined as 33,824 cm⁻¹ and 33,613 cm⁻¹, respectively. Franck-Condon simulations of the vibronic transitions showed excellent agreement with the experimental REMPI spectra, enabling precise assignment of substituent and benzene ring vibrational modes. MATI experiments yielded accurate adiabatic ionization energies (AIEs) of the cis and trans rotamers as 59,629 ± 5 cm⁻¹ and 59,432 ± 5 cm⁻¹, respectively, and identified active cationic vibrational modes in the D₀ state. Geometric parameters of PDEB in the S₀, S₁, and D₀ states were calculated at the B3PW91/aug-cc-pVTZ, TD-B3PW91/aug-cc-pVTZ, and UB3PW91/aug-cc-pVTZ levels, revealing structural evolution during electronic excitation and ionization. The effects of ethoxy substituent orientation on molecular energy, vibrational frequencies, and ionization energy are discussed, and differences in spectral characteristics between PDEB and its meta isomer (MDEB) are compared. This work provides a comprehensive spectral and structural database for p-diethoxybenzene and deepens the understanding of structure–property relationships in diethoxybenzene isomers. Full article

Supercritical CO₂ (S-CO₂) extraction is one of the most employed techniques for the extraction of bioactive compounds for its safety, effectiveness, cost-efficiency, and good environmental compliance. Smyrnium olusatrum L. (Apiaceae) is an aromatic plant of great interest due to its potential applications in pharmaceutical, agrochemical, and oleochemical fields. Its bioactivity is caused by furanosesquiterpenes, mainly represented by isofuranodiene (IFD). The extraction of this compound is usually achieved through Soxhlet or hydrodistillation. However, the latter usually leads to the thermal Cope rearrangement of IFD into its isomer curzerene, resulting in low recovery. This study reported for the first time the optimization of S-CO₂ extraction of IFD from S. olusatrum schizocarps. Pressure (MPa), extraction time (min), and static mode (%) were varied while the temperature was maintained at 45 °C to avoid IFD thermal degradation. The optimized process (50 MPa, 60 min, 25% static mode) provided an extraction yield and an IFD recovery of 8.50 and 0.94% and avoided the thermal degradation of the compound. This study demonstrated that S-CO₂ extraction is a valuable alternative to conventional hydrodistillation (extraction yield and IFD recovery of 2.64 and 0.77%) and Soxhlet (extraction yield and IFD recovery of 9.49 and 0.85%) to recover IFD from S. olusatrum. Full article

Traditional Chinese prescriptions are characterized by complex chemical constituents and wide variations in constituent content, which pose a substantial challenge to their comprehensive characterization. As a classic traditional Chinese prescription known for its heat-clearing and detoxifying properties, Huangqintang Decoction (HQD) is composed of Scutellariae Radix, Paeoniae Radix Rubra, Glycyrrhizae Radix et Rhizoma, and Jujubae Fructus. In this study, we developed an off-line two-dimensional liquid chromatography that addressed the limitations of traditional analysis of unfractionated extracts, such as restricted peak capacity, which often obscured trace components. By coupling with ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS), this study successfully performed rapid identification or characterization of the complete chemical profile of HQD. Notably, beyond high-throughput identification, this approach leveraged characteristic fragment ions and reversed-phase chromatographic behaviors to differentiate some isomers of flavonoid glycosides and triterpenoid saponins, demonstrating its depth in structural identification. Flavonoid glycoside isomers were distinguished by diagnostic neutral losses, while flavanones and chalcones were characterized by retro-Diels–Alder (RDA) and β-rearrangement, respectively. Isomers of triterpenoid saponins were inferred from aglycone-specific pathways alongside RDA cleavages. Ultimately, a total of 192 compounds were identified, including 88 flavonoids, 80 triterpenoids, 7 monoterpene glycosides, 3 fatty acid amides, 3 phenylethanoid glycosides, 4 coumarins, 3 saccharides, 1 organic acid, and 3 others. This study demonstrated that the off-line two-dimensional liquid chromatography analysis strategy significantly enhanced chromatographic resolution and expanded the coverage of trace components. It presented an effective strategy for comprehensive compound identification in complex traditional Chinese medicine prescriptions. Full article

Despite their significance as forensic targets, alkyl nitrites, classified as illegal drugs, have received little attention in forensic analysis due to their high volatility and chemical instability. Here, we present a high-performance analytical approach using a pulsed dc soft plasma ionization-quadrupole mass spectrometry (pulsed dc SPI-MS) system, uniquely designed to operate using ambient air as the discharge gas. In this system, the modulation of the duty ratio functions as a “structural probe” to identify reactive isomers. Unlike conventional dielectric barrier discharge (DBD) sources that typically operate at atmospheric pressure, our SPI system utilizes a controlled pressure regime of several kPa, where the nitrogen in the ambient air effectively functions as a third-body gas to suppress excessive internal energy. The control of the duty ratio in our pulsed dc SPI source allowed for the successful manipulation of ion–molecule reaction pathways for highly reactive analytes. By optimizing several parameters, including duty ratio and discharge pressure, we achieved a unique ionization regime where the molecular-related ion [2 M − 3 H]⁺ was predominantly detected as the base peak with minimal fragmentation. Notably, by reducing the duty ratio from 50% to 5%, both the target ion occupancy and signal intensity were significantly enhanced, achieving a limit of detection (LOD) as low as 0.16 parts per million by volume (ppmv). This sensitivity is several orders of magnitude higher than previously reported thresholds, enabling rapid identification of C4–C6 alkyl nitrite isomers. This method transforms the duty ratio into a powerful diagnostic tool for identifying reactive intermediates, providing a practical and efficient approach for the onsite identification of illegal alkyl nitrites in forensic and security fields. Full article

Heavy radioactive ion beams produced by in-flight techniques often involve long-lived excited states (isomers). This presents a challenge for reaction studies because none of the existing fragment separators worldwide can resolve isomers in-flight. Here, we propose a novel scheme to produce tagged cocktail beams or pure isomer beams using an ion storage ring. The mass resolving powers of storage rings enable us to identify and separate ions of the isomeric state from the corresponding ground state in a secondary beam. For short-lived isomers, the Rare-RI Ring (R3) facility at the RI Beam Factory (RIBF) will be available, while for long-lived isomers the Experimental Storage Ring (ESR) at the GSI/FAIR facility will be utilized. Isomers often have spins and deformations significantly different from the ground states. Studying isomer structures will provide unique insight into their specific interactions, opening a new frontier in reaction studies with radioactive ion beams in the coming years. Full article

Highly polar M-mol-X (M = alkali metal, mol = molecule, X = halogen) insertion complexes have been predicted to offer potential practical applications, including molecular interactions with light, ion-pair induced isomerization, etc. In the present work, the insertion complexes of the seven-membered, fused bicyclic norcaradiene and its monocyclic isomer trapped in Li-I, Na-I, and K-I counterion pairs were investigated using ab initio methods. The structures, stability, polarities, and simulated infrared spectra are analyzed and the effects of the insertion on the norcaradiene to cycloheptatriene isomerization process are examined. Furthermore, an uncommon bond between iodine and a fully substituted carbon atom is reported upon and hypothesized to be catalyzed by the presence of the cation in the insertion complexes. Full article

Salvia transsylvanica, an endemic Romanian sage, remains understudied despite co-occurrence with validated medicinal Salvia species. In this study, leaves and flowers were harvested weekly during flowering (May and June) and subjected to classical hydroethanolic extraction, HPLC–DAD–ESI/MSⁿ profiling, in vitro antioxidant assays (ABTS, DPPH, FRAP), and enzyme-inhibitory screening, with multivariate analysis correlating compositional patterns with bioactivity. Rosmarinic acid dominated the phenolic profile (68.6 mg/g maximum in week 4), alongside salvianolic acids (salvianolic acid K isomers) and flavonoid glycosides (luteolin, apigenin, and hispidulin hexosides). Leaf extracts displayed higher ABTS/DPPH scavenging (higher phenolic acid content), while flowers showed superior FRAP and α-glucosidase inhibition (IC₅₀ 84–143 μg/mL, higher flavonoids), with maximal values being identified during week 4. S. transsylvanica offers complementary antioxidant profiles to commercial sages, warranting future in vivo validation for therapeutic applications. Full article

We report a straightforward and versatile synthetic route to pyridinium-fused 1,3-selenazoles via the electrophilic cyclization of 2-pyridylselenyl chloride with alkynes. The reaction proceeds efficiently under mild conditions with representative terminal and internal alkynes. While the cyclization exhibits high regioselectivity favoring the 3-substituted isomer for most substrates, reactions with 2-pyridyl- and 2-quinolylacetylenes yield regioisomeric mixtures. DFT calculations rationalize this divergence, revealing a competition between kinetic and thermodynamic control; the 3-isomer is kinetically favored, while the 2-isomer is thermodynamically stabilized by an ancillary chalcogen bond between the selenium atom and the pyridine nitrogen of the alkyne substituent. Molecular structures were confirmed by single-crystal X-ray diffraction, and the non-covalent interactions governing supramolecular assembly in the solid state were rigorously analyzed using MEP surfaces, the QTAIM, and NBO analysis. Antifungal evaluation identified several compounds with notable activity against phytopathogenic fungi, highlighting the potential of this novel heterocyclic scaffold in agrochemical applications. Full article

Phenolamides in bee pollen exhibit notable bioactivities, such as antioxidant, anti-inflammatory, and antimicrobial effects. Ulcerative colitis (UC) is a prevalent intestinal disorder, while the potential effects of phenolamides on UC remain unclear. This study aims to investigate the effects and mechanisms of phenolamide extract (PAE) from apricot bee pollen on dextran sulfate sodium (DSS)-induced UC in mice. Firstly, we analyzed the main compounds of PAE. Mice were treated with PAE (100, 200, and 400 mg/kg bw) both during the 7 days preceding 2.5% DSS induction and throughout the induction period (7 days). The results show that the primary compounds of PAE were isomers of tri-p-coumaroyl spermidine (97.78 ± 2.76%). A biochemical analysis showed that PAE decreased the levels of pro-inflammatory cytokines and increased the activities of antioxidant enzymes. Regarding the gut microbiota, PAE reduced the Bacillota/Bacteroidota ratio. Additionally, PAE elevated beneficial bacteria, including norank_f_Muribaculaceae, norank_o_Clostridia_UCG-014, and Lachnospiraceae_NK4A136_group, while reducing harmful bacteria, including Escherichia-Shigella, Clostridium, and Romboutsia. A quantitative analysis of short-chain fatty acids (SCFAs) demonstrated that PAE intervention promotes the biosynthesis of SCFAs in UC mice. This study first demonstrates that PAE attenuates DSS-induced colitis by modulating gut microbiota and SCFAs, suggesting its potential as a functional dietary supplement for colitis. Full article

2-Butanol is a promising biofuel due to its favorable properties and lower microbial toxicity compared to other butanol isomers. However, microbial production remains challenging due to the absence of a native biochemical pathway for directly converting sugars into 2-butanol. To achieve this goal, glucose should be directed through the 2,3-butanediol (2,3-BD) pathway, involving α-acetolactate synthase, α-acetolactate decarboxylase, and butanediol dehydrogenase for the formation of meso-2,3-BD, followed by diol dehydratase-catalyzed conversion of meso-2,3-BD to butanone and alcohol dehydrogenase-mediated reduction in butanone to 2-butanol. In this study, we report the development of six new recombinant strains based on Klebsiella pneumoniae G31, in which the metabolic pathway for converting glucose to meso-2,3-BD was extended to 2-butanol. All engineered strains harbored the vitamin B₁₂-dependent diol dehydratase complex (pduCDEGH) from Lentilactobacillus diolivorans DSM 14421 under its native promoter control. In addition, pduQ from the same strain, and adh from Clostridium beijerinckii DSM 51 encoding alcohol dehydrogenases were expressed under native, T7, or Ptac promoters. The highest yield of 2-butanol from glucose was achieved by K. pneumoniae K6 carrying the adh gene under the control of the T7 promoter—437 mg/L. Using 2-butanone as a substrate, K6 again produced the highest titer of 2-butanol (3.9 g/L), followed by the recombinant K8 (with adh under the Ptac promoter), and notably, by the native K. pneumoniae strains. Therefore, although pduQ encodes a key alcohol dehydrogenase in L. diolivorans, it has weaker properties than adh for the K. pneumoniae host in all promoter configurations. As the high expression levels of adh under T7 promoter control were driven by the native bacterial RNA polymerase, this promoter–host combination appears particularly suitable for developing other strains of industrial relevance. Full article

Kavalactones are psychoactive substances that naturally occur in some plants, such as Piper methysticum, Alpinia zerumbet, and Achyrocline satureioides, which are considered to have a significantly positive effect on human organisms. For example, Alpinia zerumbet is classified as a life-expanding plant. Although high-pressure liquid chromatography–mass spectrometry has been used for kavalactone analysis in plant material, the fragmentation pathways of protonated kavalactone molecules are not fully known and require further detailed study. In this paper, the fragmentation pathways of [M+H]⁺ ions of twelve kavalactones, including three pairs of isomers, are discussed in detail. Special emphasis has been placed on diagnostic product ions, which are characteristic of kavalactone structures. It has been demonstrated that diagnostic ions and structure–fragmentation relationships enable the differentiation of isomeric kavalactones and may be useful for the identification of other kavalactone conjugates, such as kavalactone dimers or kavalactone glycosides. Full article

This study examines the influence of SO₂ and its hydrate H₂SO₃ on the free energies of the core autocatalytic cycle of the formose reaction. We find that SO₂ and H₂SO₃ readily condense with aldehyde and alcohol functional groups to form bisulfite analogs of formose proto-metabolites under modeled conditions. The bisulfite functional group can provide intramolecular catalytic enhancement in specific isomers towards aldol additions and the retroaldol step that regenerates two equivalents of glycolaldehyde from tetrose. The bisulfite moiety reduces the favorability of the parasitic Cannizzaro side-reaction both thermodynamically and kinetically, thus potentially furnishing more throughput towards forming sugars. As a prebiotic analog to phosphate, we find that bisulfite slightly stabilizes ribose over its C₅ aldose diastereomers thermodynamically, although the effect is modest and may be influenced by solution dynamics. Full article