Search Results (5,059)

Recent advancements in nanotechnology and materials science have enabled the development of magnetic photocatalysts with improved efficiency, stability, and reusability, offering a promising approach for wastewater treatment. The integration of magnetic nanoparticles (MNPs) into photocatalytic processes has gained significant attention as a sustainable method for addressing emerging pollutants—such as antibiotics and pharmaceutical compounds—which pose environmental and public health risks, including the proliferation of antibiotic resistance. Surface modification techniques, specifically applied to MNPs, are employed to enhance their photocatalytic performance by improving surface reactivity, reducing nanoparticle agglomeration, and increasing photocatalytic activity under both visible and ultraviolet (UV) light irradiation. These modifications also facilitate the selective adsorption and degradation of target contaminants. Importantly, the modified nanoparticles retain their magnetic properties, allowing for facile separation and reuse in multiple treatment cycles via external magnetic fields. This review provides a comprehensive overview of recent developments in surface-modified MNPs for wastewater treatment, with a focus on their physicochemical properties, surface modification strategies, and effectiveness in the removal of antibiotics from aqueous environments. Furthermore, the review discusses advantages over conventional treatment methods, current limitations, and future research directions, emphasizing the potential of this technology for sustainable and efficient water purification. Full article

Maize (Zea mays L.) is a major economic crop highly susceptible to Colletotrichum graminicola, the causal agent of anthracnose leaf blight, which causes substantial annual yield losses. This fungal pathogen employs numerous effectors to manipulate plant immunity, yet the functions of many secreted proteins during biphasic infection remain poorly characterized. In this study, we identified CgMas2, a candidate secreted protein in C. graminicola and a homolog of Magnaporthe oryzae MoMas2. Deletion of CgMAS2 in the wild-type strain CgM2 did not affect fungal vegetative growth or conidial morphology but significantly impaired virulence on maize leaves. Leaf sheath infection assays revealed that CgMas2 is required for biotrophic invasive hyphal growth, as the mutant showed defective spreading of invasive hyphae to adjacent cells. Subcellular localization analysis indicated that CgMas2 localizes to the cytoplasm of conidia and to the primary infection hyphae. Furthermore, DAB staining demonstrated that disrupt of CgMAS2 leads to host reactive oxygen species (ROS) accumulation. Comparative transcriptome analysis of maize infected with ΔCgmas2 versus CgM2 revealed enrichment of GO terms related to peroxisome and defense response, along with up-regulation of benzoxazinoid biosynthesis genes (benzoxazinone biosynthesis 3, 4 and 5) at 60 h post-inoculation (hpi). Conversely, six ethylene-responsive transcription factors (ERF2, ERF3, ERF56, ERF112, ERF115 and ERF118) involved in ethylene signaling pathways were down-regulated at 96 hpi. These expression patterns were validated by RT-qPCR. Collectively, our results demonstrate that CgMas2 not only promotes invasive hyphal growth during the biotrophic stage but may also modulate phytohormone signaling and defense compound biosynthesis during the necrotrophic phase of infection. Full article

Multidrug resistance (MDR) is a central cause of chemotherapy failure and tumor recurrence and metastasis, and its mechanism involves enhanced drug efflux, target mutation, upregulation of DNA repair and remodeling of the tumor microenvironment. ABC transporter protein (P-gp, MRP, and BCRP)-mediated efflux of drugs is the most intensively researched aspect of the study, but the first three generations of small-molecule reversal agents were stopped in the clinic because of toxicity or pharmacokinetic defects. Natural products are considered as the fourth generation of MDR reversal agents due to their structural diversity, multi-targeting and low toxicity. In this paper, we systematically summarize the inhibitory activities of monoterpenes, sesquiterpenes, diterpenes and triterpenes against ABC transporter proteins in in vitro and in vivo models and focus on the new mechanism of reversing drug resistance by blocking efflux pumps, modulating signaling pathways such as PI3K-AKT, Nrf2, NF-κB and remodeling the tumor microenvironment. For example, Terpenoids possess irreplaceable core advantages over traditional multidrug resistance (MDR) reversers: Compared with the first three generations of synthetic reversers, natural/semisynthetic terpenoids integrate low toxicity (mostly derived from edible medicinal plants, half-maximal inhibitory concentration IC₅₀ > 50 μM), high target specificity (e.g., oleanolic acid specifically inhibits the ATP-binding cassette (ABC) transporter subtype ABCC1 without cross-reactivity with ABCB1), and multi-mechanistic synergistic effects (e.g., β-caryophyllene simultaneously mediates the dual effects of “ABCB1 efflux inhibition + apoptotic pathway activation”). These unique characteristics enable terpenoids to effectively circumvent key limitations of traditional synthetic reversers, such as high toxicity and severe drug–drug interactions. Among them, lupane-type derivative BBA and euphane-type sooneuphanone D (triterpenoids), as well as dihydro-β-agarofuran-type compounds and sesquiterpene lactone Conferone (sesquiterpenoids), have emerged as the core lead compounds with the greatest translational potential in current MDR reverser research, attributed to their potent in vitro and in vivo MDR reversal activity, low toxicity, and excellent druggable modifiability. At the same time, we point out bottlenecks, such as low bioavailability, insufficient in vivo evidence, and unclear structure–activity relationship and put forward a proposal to address these bottlenecks. At the same time, the bottlenecks of low bioavailability, insufficient vivo evidence and unclear structure–activity relationship have been pointed out, and future research directions such as nano-delivery, structural optimization and combination strategies have been proposed to provide theoretical foundations and potential practical pathways for the clinical translation research of terpenoid compounds, whose clinical application still requires further in vivo validation and translational research support. Full article

Expanding the chemical diversity of DNA–encoded libraries (DELs) is crucial for identifying binders to emerging drug targets using DEL technology. In the present study, as part of our ongoing efforts to develop on–DNA diazide platforms (D–DAPs)—platform molecules possessing both aromatic and aliphatic azide groups on a single core reactive scaffold—we designed and synthesized a new compact diazide platform, designated as a compact D–DAP (C–D–DAP). This molecule is based on a low–molecular–weight reactive scaffold, 3–azido–5–(azidomethyl)benzoic acid, to facilitate small–molecule drug discovery targeting enzymes and G protein–coupled receptors (GPCRs). Furthermore, we established two distinct stepwise warhead construction strategies that exploit the chemoselective transformations of the azide groups in the C–D–DAP, which exhibit different reactivities. In addition, four virtual DELs were generated based on stepwise warhead elaboration from the C–D–DAP scaffold. Comparative chemical diversity analysis against bioactive compounds from ChEMBL revealed that these virtual libraries populate structural regions that are sparsely represented among known molecules. Each virtual library also occupies a distinct region of structural space relative to the others and displays intermediate quantitative estimate of drug–likeness (QED) values. Full article

VOCs are significant precursors for the formation of O₃ and SOA, directly impacting human health. This study employs multiple approaches to analyzing atmospheric VOCs by focusing on OVOCs including aldehydes, ketones, and phenols, with a case study in Beijing, China. We analyzed the concentration levels and compositions of VOCs and their atmospheric activities, offering a new perspective on VOCs. This analysis was conducted through offline measurements of volatile phenols and carbonyl compounds, complemented by online VOC observations during the summer period of high O₃ levels. The total atmospheric VOCs concentration was found to be 51.29 ± 10.01 ppbv, with phenols contributing the most (38.87 ± 11.57%), followed by carbonyls (34.91 ± 6.85%), and aromatics (2.70 ± 1.03%, each compound is assigned to only one category based on its primary functional group, with no double counting). Carbonyls were the largest contributors to the OFP at 59.03 ± 14.69%, followed by phenols (19.94 ± 4.27%). The contribution of phenols to the SOAFP (43.37 ± 9.53%) and the L_OH (67.74 ± 16.72%) is dominant. Among all quantified VOC species, phenol and formaldehyde exhibited the highest species-level contributions to atmospheric reactivity metrics, including L_OH, OFP and SOAFP, owing to their combination of elevated concentrations and large kinetic or MIR coefficients. Using the PMF model for source analysis, six main sources of volatile organic compounds were identified. Solvent use and organic chemicals production were found to be the primary contributors, accounting for 31.76% of the total VOCs emissions, followed by diesel vehicle exhaust (17.80%) and biogenic sources (15.51%). This study introduces important OVOCs such as phenols, re-evaluates the importance of OVOCs and their role in atmospheric chemical processes, and provides new insights into atmospheric VOCs. These findings are crucial for developing effective air pollution control strategies and improving air quality. This study emphasizes the importance of OVOCs, especially aldehydes and phenols, in the mechanism of summer O₃ generation. Full article

As a natural flavonoid compound, quercetin possesses excellent antioxidant, anti-inflammatory and anti-atherosclerotic activities. However, the poor water solubility and sensitivity to the environment severely limit the application of quercetin. Initially, quercetin-loaded zein/carboxymethyl chitosan nanoparticles (ZCQ NPs) were prepared using an anti-solvent precipitation method. The fabricated ZCQ NPs exhibited a small particle size and polydispersity index (PDI). The ZCQ NPs had a negative zeta potential with an absolute value of 41.50 ± 1.76 mV. ZCQ NPs could remain highly stable against light, heat and ion strength. In addition, ZCQ NPs maintained good monodispersity and displayed minimal changes in particle size under long-term storage conditions. Additionally, a superior antioxidant capacity of ZCQ NPs was also observed in the free radical and reactive oxygen species (ROS) scavenging study compared to that of free quercetin. All these results of this study suggest that ZCQ NPs could serve as an effective drug delivery system for encapsulating and delivering quercetin. Full article

The lactoperoxidase system (LpoS) is an enzymatic antimicrobial mechanism of saliva that oxidizes (pseudo)halide substrates to reactive compounds capable of limiting microbial growth. This study evaluated how different LpoS variants—utilizing iodide (LpoS-I⁻), thiocyanate (LpoS-SCN⁻), selenocyanate (LpoS-SeCN⁻), and a thiocyanate–iodide mixture (LpoS-SCN⁻ + I⁻)—affect virulence, metabolism, and biofilm structure in Streptococcus mutans. Using qRT-PCR, pyruvate assays, MTT reduction, and confocal microscopy, we found that LpoS-I⁻ most effectively reduced atpD and ldh expression, impaired acid tolerance, and decreased lactate and pyruvate production. LpoS-SCN⁻ and LpoS-SeCN⁻ also downregulated atpD and gtfB, although LpoS-SeCN⁻ upregulated ldh. Despite minimal structural biofilm disruption, LpoS-I⁻ markedly inhibited intracellular and extracellular pyruvate accumulation, suggesting altered glycolytic flux. These findings indicate that iodide-based LPO systems modulate key metabolic and regulatory pathways in S. mutans and may hold potential for inclusion in anticaries oral formulations. Full article

The diterpene sessein, isolated from Salvia sessei, is a metabolite of interest due to its conjugated p-quinone system, δ-lactone ring, and phenolic hydroxyl in C-12. These functionalities make it an ideal starting point for reactivity studies and semi-synthetic derivatization. In this work, we report the obtainment of two derivatives by selective esterification of phenolic hydroxyl in C-12, through acetylation and benzoylation reactions under mild conditions and with high yields. The structures were characterized by UPLC-MS, FTIR, and NMR spectroscopy ¹H, ¹³C, and 2D, which allowed to precisely confirm the modifications made in the derivatives. These results confirm that hydroxyl in C-12 constitutes a privileged site of reactivity within the royleanone family, consolidating sessein as a versatile nucleus for the generation of derivatives. Finally, the preliminary evaluation of the antimicrobial activity showed that sessein shows a broad spectrum of action against Gram-positive, Gram-negative, and Candida albicans strains. The acetylated derivative showed an increase in activity against gram-negative bacteria, while the benzoyl derivative had a loss of effect at the concentrations evaluated. These findings demonstrate that structural modifications influence the properties of the derivatives with respect to the compound sessein. Full article

Endoperoxides constitute a distinctive class of highly oxygenated terpenoids defined by the presence of a cyclic peroxide (–O–O–) bond, a structural motif responsible for their pronounced chemical reactivity and diverse biological effects. Naturally occurring endoperoxide-containing terpenoids are broadly distributed across terrestrial and marine taxa, including higher plants, algae, fungi, and bryophytes, where they are believed to participate in chemical defense and ecological interactions. This review provides a comprehensive overview of naturally occurring endoperoxide terpenoids, focusing on their natural sources, structural diversity, and reported biological activities. Particular emphasis is placed on compounds exhibiting antiprotozoal and antitumor activities, exemplified by artemisinin and its derivatives, which remain cornerstone agents in antimalarial therapy and continue to attract interest for their anticancer potential. Structure–activity relationship (SAR) analysis, supported by computational prediction using the PASS (Prediction of Activity Spectra for Substances) platform, is employed to examine correlations between peroxide-containing frameworks and biological function. Comparative assessment of experimental data and predicted activity profiles identifies key structural features associated with antiprotozoal, antineoplastic, and anti-inflammatory effects. Collectively, this review highlights endoperoxides as a valuable and chemically distinctive class of bioactive natural products and discusses their promise and limitations as leads for further pharmacological development, particularly in light of their intrinsic reactivity and stability challenges. Full article

Ultraviolet B radiation is a major cause of skin aging, cellular senescence, and inflammaging, mediated by the excessive production of reactive oxygen species (ROS) and induction of apoptosis. This study evaluated the photo-protective effects of astaxanthin, one of the strongest natural antioxidants, in UVB-treated keratinocytes. The antioxidant capacity of astaxanthin was evaluated using ABTS, DPPH, and NBT/riboflavin/SOD assays. HaCaT cells were exposed to 30 mJ/cm² of UVB radiation. Photoprotective effects and accumulated ROS were evaluated in UVB-irradiated HaCaT cells by MTT and DCFH-DA assays. Nitric oxide levels were quantified using the Griess reagent. Apoptosis was assessed by dual staining using acridine orange/ethidium bromide, lysosomal integrity by acridine orange uptake, and cell migration by scratch assay. Cell adhesion was assessed on ECM-coated Nunc plates. Finally, we formulated a 0.5% astaxanthin-enriched cream. Astaxanthin mitigated UVB-induced damage by reducing intracellular ROS levels by 3.7-fold, decreasing nitric oxide production to 29.8 ± 7.7% at the highest concentration, and maintaining lysosomal integrity. The carotenoid significantly enhanced cell viability, increasing it from 60.64 ± 8.3% in UV-treated cells to 102.1 ± 3.22% at 40 µM. Moreover, treated cells showed a significant reduction (p < 0.001) in the apoptotic rate (37.7 ± 3.1 vs. 87.7 ± 3.8 in UVB-irradiated cells, as evidenced by reduced chromatin condensation and nuclear fragmentation. Astaxanthin also enhanced tissue repair, as evidenced by increased cell migration and adhesion to several extracellular matrix (ECM) proteins (poly-L-lysine, laminin, fibrinogen, vitronectin and collagen I). In silico molecular docking predicted strong binding affinities between astaxanthin and key cellular targets, including JAK2 (−9.9 kcal/mol, highest affinity), STAT3, FAK, COX-2, NF-k-B, MMP2, and MMP9. The formulated cream demonstrated an in vitro SPF of 7.2 ± 2.5. Astaxanthin acts as a multifunctional photoprotective compound, providing a strong rationale for its incorporation into cosmetic and dermatological formulations, as further supported by the successful formulation and in vitro SPF estimation of an astaxanthin-enriched cream. Full article

The reactions of hydrogen transfer by hydroxyl radicals involving polycyclic aromatic hydrocarbons (PAH) are important, because these compounds contribute to environmental pollution and negatively affect human health. Hydroxyl radicals play a key role in atmospheric processes. This study analyzed the influence of the substituent and the number of aromatic rings in the compound on the kinetics of the hydrogen-transfer reaction. This work proposes for the first time a quantitative structure–activity relationship-based statistical framework combining design of experiments and tunneling corrections to predict PAH + ·OH kinetics. The main objective of this research was to identify which molecular features and substituent effects most strongly govern tunneling and reactivity, thereby enabling the rational prediction of PAH behavior in atmospheric and combustion environments. For this purpose, a quantitative structure–activity relationship model was developed using 22 descriptors, and their relationship with the kinetic parameters of the reaction was determined using statistical tools such as design of experiments and partial least squares. Full article

To address gaps in the characterization of Roman chamomile (Anthemis nobilis L., Asteraceae)—an ethnobotanically and commercially important species—we profiled its essential oil (EO), focusing on esters that are incompletely characterized or unreported. Comprehensive GC-MS of two commercial EOs and their chromatographic fractions, combined with synthesis and co-injection of reference compounds, enabled the identification of 190 constituents. We uncovered a homologous series of angelates, tiglates, and senecioates by partial-ion-current (PIC) screening (m/z 55, 83, 100, 101), augmented by co-injection and NMR confirmation. Among these EO constituents, four esters, methallyl 3-methylbutanoate (6h), methallyl senecioate (3h), 3-methylpentyl 2-methylbutanoate (5c), and 5-methylhexyl angelate (2g) are reported here as new natural products and previously unreported compounds in the literature. Selected methacrylates and related α,β-unsaturated esters underwent model Michael additions to methanethiol (generated in situ from dimethyl disulfide and NaBH₄), confirming their thiol-acceptor reactivity. In an Artemia salina assay, the EO and most esters were non-toxic; methacrylates showed only low toxicity at the highest concentrations. These results refine the chemical map of A. nobilis EO and highlight specific ester families for future mechanistic and biological evaluation. Full article

Nucleophilic ring-opening of bis(oxiranes), containing several reactive centers, can be used to elaborate straightforward atom-economy and stereoselective approaches to polyfunctionalized compounds. In the present work, ring-opening of cis- and trans-diastereomers of a spirocyclic bis(oxirane), containing a cyclooctane core (namely, 1,8-dioxadispiro[2.3.2.3]dodecane), upon treatment with various amines, was studied. Trans-isomer afforded aminoalcohols with 9-oxabicyclo[3.3.1]nonane moiety, formed via domino-process, including opening of an oxirane ring followed by intramolecular cyclization. Ring-opening of cis-isomer gave aminosubstituted cis-cyclooctane-1,5-diols, derived from independent reaction of two oxirane moieties. Activation of oxirane rings by the addition of LiClO₄, acting as a Lewis acid, allowed the involvement of a number of primary and secondary aliphatic amines as well as aniline derivatives in the reaction. Scope and limitations of the reaction were studied and a series of aminoalcohols with a 9-oxabicyclo[3.3.1]nonane core and symmetric diaminodiols with a cyclooctane core were obtained. Full article

Chemotherapy resistance in colorectal cancer (CRC) represents a critical clinical challenge leading to treatment failure and poor patient prognosis. Artemisinin is a natural product isolated from Artemisia annua, and its clinically relevant derivatives include dihydroartemisinin (DHA) and artesunate. Beyond their established antimalarial efficacy, both artemisinin and its derivatives—collectively referred to as artemisinin-derived compounds (ADs)—have been increasingly recognized for their unique potential to reverse multidrug resistance in cancer. Unlike previous reviews focusing on isolated mechanisms, this review systematically constructs a multidimensional, synergistic attack network centered on ADs to elucidate their integrated actions against chemotherapy-resistant CRC. Mechanistically, ADs suppress cancer stem cell (CSC)-associated resistance phenotypes while concurrently reshaping the tumor immune microenvironment, highlighting a functional coupling between stemness inhibition and immune remodeling. In parallel, this review presents apoptosis reactivation and ferroptosis induction as complementary, dual-track cell death strategies that collectively circumvent apoptosis resistance. Moreover, ADs exert “one-strike–multiple-effects” through coordinated regulation of pro-survival signaling networks and immune-related pathways, including the induction of immunogenic cell death (ICD) and the modulation of immunosuppressive macrophage subsets. Beyond mechanistic insights, this review integrates emerging translational considerations, including clinical pharmacokinetics, safety and tolerability, formulation and delivery strategies, and rational combination therapy paradigms in CRC. Collectively, these findings position ADs as multi-dimensional modulators rather than a single-agent cytotoxic, providing a coherent mechanistic and translational rationale for their further development in chemotherapy-resistant CRC. Full article

Sulfidized nano zero-valent iron (S-nZVI) particles are known to stimulate the reductive removal of various oxyanions due to enhanced electron selectivity and electron conductivity between the Fe(0) core and the target compound. Sulfidation creates a number of reactive sulfur species, the role of which has not yet been investigated in the context of S-nZVI. In this study, we investigated the contribution of reactive sulfur species to Se(VI) reduction by S-nZVI at different molar S/Fe ratios (0, 0.1 and 0.6) and Se(VI) concentrations (0, 5 and 50 mg L⁻¹). In the presence of S-nZVI, the rate of reduction was accelerated by a factor of up to ten. X-ray Absorption Near-Edge Structure (XANES) spectroscopy and surface-sensitive X-ray photoelectron spectroscopy (XPS) identified Se(0) as the predominant reduction product (~90%). The reduction reaction was accompanied by a loss of FeS and the formation of surface-bound Fe(II) polysulfide (FeSx) and S(0) species. Likewise, wet chemical extraction techniques suggested a direct involvement of acid volatile sulfide (AVS) species (surface-bound FeS) in the reduction of Se(IV) to Se(0) and formation of S(0). Mass balance estimates reveal that between 9 and 15% of the conversion of Se(0) originates from oxidation of FeS to FeSx. From these findings, we propose that surface-bound Fe sulfide species are important but previously overlooked reactants contributing to the reduction of oxyanions associated with S-nZVI particles, as well as in natural environments undergoing sulfidation reactions. Full article