Search Results (3,966)

Grouting technology can be employed to repair cracks in an aquifer to maintain its stability; however, existing grouting materials tend to come with problems such as low flexural strength, poor cracking resistance, and the coupled effects of fiber reinforcement and sulfoaluminate cement (SAC) addition on hydrate evolution, and pore-refinement and crack-resistance mechanisms in coal-based solid-waste cementitious grouts remain insufficiently understood. In this paper, fiber-modified coal-based solid-waste grouting (F-CWG) materials were prepared by mixing different contents of sulfoaluminate cement (SAC) and different fibers. The mechanical strength, microstructure, hydration products, and pore evolution characteristics were analyzed by means of mechanical property tests, energy-dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and nuclear magnetic resonance (NMR). The results show that the mechanical strength decreases at first due to insufficient early-stage hydration products. Specifically, the 28 d compressive and flexural strengths decrease from 15.34 MPa and 4.55 MPa at 0% SAC to 8.18 MPa and 2.99 MPa at 40% SAC but increase again to 13.36 MPa and 3.79 MPa at 60% SAC as the formation of ettringite (AFt) and C–S–H is promoted with higher SAC content. Among the tested fibers, a dosage of 0.6% generally improves mechanical strength and refines pore structure, with PVA and steel fibers showing the most pronounced effects. Our results reveal the mechanism behind the enhancement of cracking resistance in F-CWG materials, providing a scientific basis for grouting and water-preservation mining, and are of great significance in improving the utilization rate of coal-based solid waste. Full article

Alzheimer’s disease (AD) is a prevalent neurodegenerative condition that progressively impairs cognitive processes, particularly learning and memory. A key pathological feature of AD involves senile plaques mainly composed of β-amyloid (Aβ) peptides, generated via the amyloidogenic pathway from amyloid precursor protein (APP) through sequential β-secretase (BACE1) and γ-secretase cleavage, positioning BACE1 inhibition as a prime therapeutic target. In this study, we applied bioassay-guided fractionation of the butanol-soluble fraction from Dryopteris crassirhizoma rhizomes, previously reported to inhibit Aβ production, to isolate and characterize Aβ-lowering constituents. Through successive chromatographic steps, nine compounds were isolated and structurally classified into flavonoids, chromones, and phloroglucinols, including epicatechin (1), β-carboxymethyl-(-)-epicatechin (2), 7-methoxy-isobiflorin (3), biflorin (4), eriodictyol (5), noreugenin (6), phloroglucinols (butyrylphloroglucinol (7), 2-propionyl-4-methylphloroglucinol (8), and 2-butyryl-4-methylphloroglucinol (9) by comprehensive spectroscopic analysis (NMR, MS, UV, IR). These compounds were assessed for effects on sAPPβ and BACE1 (β-secretase) levels by Western blot, with Aβ production quantified via ELISA in a cellular AD model (APP-CHO cells). Compounds 5–9 significantly reduced sAPPβ and BACE1 expression while potently suppressing Aβ generation. These results demonstrate that diverse constituents from D. crassirhizoma rhizomes inhibited Aβ production through BACE1 suppression, highlighting their potential as natural lead compounds for AD prevention or therapy. Full article

The increasing demand for sustainable and functional plant-based foods has driven interest in 3D food printing technologies, which require bioinks with tailored rheological and structural properties. This study investigated the effects of transglutaminase (TGase) on the structure–function relationships of plant protein bioinks from fava bean, mung bean, pea, and soybean. TNBS assays showed a dose-dependent increase in crosslinking (27.46–64.57%), with soybean and pea proteins exhibiting the highest reactivity (p < 0.05). ¹H-NMR confirmed protein-specific ε-(γ-glutamyl)lysine bond formation, and synchrotron FTIR revealed TGase-induced α-helix reduction and β-sheet enrichment, indicative of network formation across all proteins. SDS-PAGE analysis demonstrated TGase-mediated polymerization with high-molecular-weight aggregates, particularly pronounced in soybean, while SEM images revealed denser, more continuous protein networks compared to untreated samples. Rheological characterization showed enhanced viscoelasticity and shear-thinning behavior in all bioinks, supporting extrusion and post-printing stability. Textural analysis indicated improvements in hardness, springiness, cohesiveness, and chewiness across all proteins, with soybean and fava showing the most pronounced increases. These results demonstrate that TGase is a versatile tool for reinforcing plant protein networks, improving printability, structural integrity, and texture in 3D-printed foods, while highlighting protein-specific differences in response. Full article

A novel steviol glycoside, Rebaudioside D17, was identified from the leaf extract of Stevia rebaudiana Bertoni. This compound features a rare β-1→4 glycosidic linkage between two glucose units at the C19 position, distinguishing it from its structural isomer, Rebaudioside D. The aim of this study was to isolate and characterize Rebaudioside D17 and investigate its biosynthetic origin. The compound was isolated and structurally characterized using comprehensive NMR spectroscopy including ¹H, ¹³C, COSY, NOESY, Heteronuclear Single Quantum Coherence–Distortionless Enhancement by Polarization Transfer (HSQC-DEPT), Heteronuclear Multiple Bond Correlation (HMBC), Heteronuclear Single Quantum Coherence–Total Correlated Spectroscopy (HSQC-TOCSY), along with mass spectrometry analysis. A tentative biosynthetic pathway is proposed, involving Rebaudioside E19, a putative intermediate bearing the same β-1→4 glycosidic linkage at C19. Rebaudioside E19 may serve as a common precursor to both Rebaudioside D17 and Rebaudioside U3, a minor steviol glycoside previously reported in Stevia rebaudiana leaf extract, which also contains the same β-1→4 glycosidic linkage. The discovery of Rebaudioside D17 expands the known diversity of steviol glycosides and provides new insights into glycosylation patterns in Stevia rebaudiana, which may support the development and production of novel sweeteners with improved sensory and physicochemical properties. 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

Brown algae of the Cystoseira genus are recognized as valuable sources of bioactive compounds, including polysaccharides. Within the framework of current restoration efforts regarding damaged Ericaria amentacea populations in the Mediterranean Sea, the valorization of apices derived from ex situ cultivation waste represents a sustainable opportunity for industrial and biomedical applications. In this study, sodium alginate (SA) was extracted from E. amentacea apex by-products using a hydrothermal–alkaline method and subsequently chemically characterized. FTIR analysis showed O-H, C-H, and COO- stretching compatible with commercial alginates, while 1H-NMR spectroscopy indicated high β-D-mannuronic acid content, with an M/G ratio of 2.33. The extracted SA displayed a molecular weight of 1 × 10⁴ g/mol and a polydispersity index of 3.5. The bioactive properties of the SA extract were investigated in chemico and in vitro. SA exhibited remarkable antioxidant activity, showing significant DPPH and nitric oxide-radical-scavenging capacity. Furthermore, SA demonstrated a strong anti-inflammatory effect in LPS-stimulated macrophages through modulation of several inflammatory mediators (i.e., IL-6, IL-8/CXCL5, MCP-1, and TNF-α). In particular, SA promoted a striking iNOS gene expression inhibition, which, paired with its direct NO-scavenging ability, paves the way for future pharmacological use of E. amentacea derivatives, particularly if sustainably obtained from restoration activity waste. Full article

Seven amidrazones containing a characteristic NH₂–N=C(Ar¹)–NHAr² moiety, where Ar¹, Ar² are phenyl, 4-methylphenyl, 4-nitrophenyl, 2-pyridyl, and 4-pyridyl substituents, denoted as 2a–2g, were synthesized by the reactions between thioamides and hydrazine. Their molecular structures were confirmed by ¹H, ¹³C, ¹H-¹³C HMQC, ¹H-¹³C HMBC, and ¹H-¹⁵N HMBC NMR spectroscopy, with complete assignment of the detected signals, as well as by high-resolution mass spectra. The biological activity of all compounds was studied, exhibiting antioxidant properties determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods, inhibitory potential against digestive tract enzymes (α-amylase, lipase, pepsin), cytotoxicity (hemolysis), and antimicrobial activities (against Gram-positive and Gram-negative bacteria, and a fungus). The antioxidant activity of the studied amidrazones varied from 83.34% to 93.27% and 1.01–5.79 mM FeSO₄ for the DPPH and FRAP methods, respectively. Moreover, these derivatives revealed inhibition potential against α-amylase (28.6–86.8%), lipase (28.0–60.0%), and pepsin (34.1–76.6%), which increased when increasing their concentrations from 0.2 to 1 mg/mL. Among them, compound 2d (possessing 2-pyridyl and 4-nitrophenyl substituents) stood out in particular, as a potent antioxidant (DPPH = 90.43%, FRAP = 4.73 Mm FeSO₄) with the highest activity against Gram-positive bacteria: S. aureus (MIC = 64 μg/mL), G. rubripertincta (MIC = 64 μg/mL), and fungus: C. albicans (MIC = 32 μg/mL); high α-amylase (86.8%) inhibition at the highest concentration (1 mg/mL); and lipase (38.0%) and pepsin (43.8%) inhibition at the lowest concentration (0.2 mg/mL). The obtained results were analyzed by unsupervised multivariate techniques to confirm significant differences in the biological activity of amidrazones depending on the Ar¹ and Ar² substituents. Full article

Siraitia grosvenorii (Swingle) C. Jeffrey is widely recognized for its anti-inflammatory properties, as well as its roles in lung purification, phlegm elimination, intestinal function regulation, and anti-tumor activity. Its pharmacological activity is attributed to a diversity of functional components. However, due to the extensive application of sweet glycosides in food additives, there have been few studies on non-sweet glycosides, particularly those with high polarity. This paper investigates the chemical constituents in the non-sweet glycosides fraction of S. grosvenorii juice. First, an MCI GEL CHP20P chromatographic column was utilized to enrich the non-sweet glycosides fraction. Furthermore, two-step medium-pressure liquid chromatography (MPLC) was performed for the efficient preparative separation of high-polarity non-sweet glycosides with similar structures, using C18 and silica gel as stationary phases, respectively. Seven non-sweet glycoside compounds were identified through NMR and mass spectrometry analyses, including three new compounds (4-hydroxyphenylethanol 4-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside, 4-hydroxyphenylethanol 4-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside and n-butanol 1-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside), as well as four known ones (α-D-glucopyranosyl-(1→4)-D-glucose, α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside, methoxy hydroquinone diglucoside, and β-D-glucopyranoside). The results demonstrate that mixed-mode MPLC using different stationary phases is an efficient approach for separating non-sweet glycosides from S. grosvenorii. Full article

A growing body of evidence indicates that artificial manipulation of transcriptional regulation is a powerful approach to activate cryptic biosynthetic gene clusters (BGCs) of secondary metabolites (SMs) in fungi. In this study, one mutant strain MNP-2-OE::veA was constructed by overexpressing the global transcription regulator veA in an Arctic-derived strain Aspergillus sydowii MNP-2. Chemical investigation of the mutant OE::veA resulted in the isolation of one novel polyhydroxy anthraquinone (1) together with nine known metabolites (2–10), which were unambiguously characterized by various spectroscopic methods including 1D and 2D NMR and HR-ESI-MS as well as via comparison with literature data. Biosynthetically, compounds 1 and 10 as new arising chemicals were, respectively, formed by type II polyketide synthase (T2PK) and non-ribosomal peptide synthetase (NRPS), which were silent in the wild-type (WT) strain MNP-2. A bioassay showed that only compound 3 had weak inhibitory effect on human pathogen Candida albicans, with a MIC value of 64 ug/mL, and 4 displayed in vitro weak cytotoxic activity against HCT116 cells (IC₅₀ = 44.47 μM). These results indicate that overexpression of veA effectively awakened the cryptic BGCs in fungal strains and enhanced their structural diversity in natural products. Full article

Six new diterpenoids, including two verticillane ghardaqenoids A–B (1–2) and four dolabellane ghardaqenoids C–F (3–6), were isolated from the soft coral Heteroxenia ghardaqensis collected in the South China Sea. The structures of ghardaqenoids A, D, and E (1, 4, 5) were determined by X-ray diffraction. Ghardaqenoids B, C, and F (2, 3, 6) were identified on the basis of NMR data, DP4+, and ECD spectral data. In particular, compound 6 exhibited strong in vitro lipid-lowering activity in free fatty acid (FFA)-induced HepG2 cells and liver organoids. Further mechanistic studies revealed that compound 6 regulated AMPK-related proteins and genes, thereby inhibiting the accumulation of triglycerides (TG) and total cholesterol (TC). These findings suggested that pharmacological AMPK activation serves as a promising role in lipid-lowering therapeutic strategies. Full article

Sarcopenia, an age-related muscle atrophy disease, is a major health concern in aging societies and is closely associated with severe chronic diseases. Its primary pathogenesis involves oxidative stress-induced apoptosis in muscle cells and an imbalance in protein metabolism. This study evaluated the potential of Rhododendron mucronulatum branch extract (RMB) and its major flavonoids, taxifolin-3-O-arabinopyranoside (Tax-G) and taxifolin (Tax-A), as natural therapeutic agents for sarcopenia. Phytochemical analyses were performed using TLC, HPLC, LC-MS/MS, and NMR, and Tax-G and Tax-A were isolated from RMB. In vitro models of apoptosis and muscle atrophy were established in C2C12 cells using H₂O₂ and dexamethasone (DEX), respectively. Cell viability, myotube diameter, and protein expression related to apoptosis and muscle differentiation were assessed. All three substances reduced H₂O₂-induced apoptosis by increasing Bcl-2 and inhibiting cleaved caspase-3 and PARP. They also attenuated DEX-induced muscle atrophy by suppressing Atrogin-1, MuRF1, and FoxO3α while promoting MyoD, Myogenin, Akt, and mTOR. Although Tax-A showed the highest activity, Tax-G exhibited comparable effects with lower cytotoxicity. These findings demonstrate that RMB and its active compounds protect muscle cells by regulating apoptosis and muscle metabolism, suggesting their potential as safe and functional natural materials for the prevention of sarcopenia. Full article

Supramolecular nanoparticles offer an efficient strategy to enhance the solubility, stability, and bioavailability of poorly water-soluble therapeutic molecules. In this study, water-dispersible SNPs were successfully prepared from dicarboxyl-bis-pillar[5]arene (H) and cetyltrimethylammonium bromide (CTAB) using a microemulsion method. Dynamic light scattering revealed that the resulting CTAB/H nanoparticles possessed a size distribution centered around 40 nm, a positive surface charge (+15 mV), and exhibited high colloidal stability over three months. ¹H NMR, 2D TOCSY, 2D NOESY, diffusion ordered NMR spectroscopy, and UV-Vis investigations confirmed the inclusion of the CTAB alkyl chain within the pillar[5]arene cavity, supporting the formation of stable supramolecular assemblies capable of efficiently encapsulating the poorly water-soluble flavonol quercetin (Q). The CTAB/H system displayed low cytotoxicity (up to 50 µg/mL) and pronounced antioxidant activity, as evidenced by DPPH, ABTS, and FRAP assays. Quercetin-loaded nanoparticles (CTAB/H/Q) enhanced cellular uptake and exhibited a marked cytoprotective effect against H₂O₂-induced oxidative stress in NIH-3T3 fibroblasts. Full article

The reaction of aliphatic aldehydes with the tautomers 6,6-dimethyl-4-hydroxy-2H-thiopyrane-2-thione and 6,6-dimethyl-2-mercapto-4H-thiopyrane-4-one is reported to yield spiro compounds. However, the spiro compound of the reaction with formaldehyde is postulated, but has not been isolated to date. Due to a change in reaction conditions, we managed to isolate (RS)-6,6,7′,7′-Tetramethyl-2-sulfanylidene-5,6,6′,7′-tetrahydro-2H,2′H,4H,4′H,5′H-spiro[thiopyran-3,3′-thiopyrano [2,3-b]thiopyran]-4,5′-dione for the first time. The structure was proven with the help of a single X-ray crystal analysis. Furthermore, the new compound was fully characterized using one- and two- dimensional NMR techniques such as ¹H, ¹³C, DEPT, COSY, HSQC and HMBC spectra, as well as IR and HRMS measurements. Full article

The genus Plantago (Plantaginaceae) is widely distributed worldwide. The Plantago species are used in traditional medicine as wound healers, anti-inflammatory agents, antipyretics, and analgesics. This study aimed to investigate the phytochemical composition from the aerial parts of Plantago indica L. and to evaluate its biological activities. Isolation studies and in vitro investigations were conducted on an aqueous phase of 80% EtOH extract of Plantago indica. In addition, in vivo studies were carried out using the MeOH, 80% EtOH, and water extracts. Plantarenaloside (1), 3-oxo-α-ionol β-glucoside (2), martynoside (3), acteoside (4), feruloyl gardoside (5), and ursolic acid (6) were isolated from the extract. The structures of the compounds were elucidated using 1D- and 2D-NMR and ESI-MS analyses. The extract, fractions, and pure compounds were tested in vitro for cytotoxicity (MTT), anti-inflammatory activity (NO, IL-6, and TNF-α production), wound healing (scratch test), and antioxidant capacity (DPPH, ABTS, SO). Feruloyl gardoside (20.11–58.27%) significantly reduced NO levels at concentrations of 25–100 µM. It significantly reduced IL-6 levels (40.17%) at 100 µM. Additionally, the in vivo anti-inflammatory (acetic acid-induced vascular permeability) and wound healing (incision and excision models) effects of the extracts were investigated. The findings suggest that P. indica may be considered to be a potential therapeutic option for managing inflammation and for promoting wound healing. Full article

Background/Objectives: Microalgae are recognized as prolific producers of bioactive metabolites with pharmaceutical potential. This study aimed to isolate and characterize cytotoxic constituents from selected cytotoxic microalgae, collected in Hue city, Vietnam. Methods: Microalgal samples were collected from freshwater bodies, morphologically identified, and maintained in laboratory culture. Thirteen strains were successfully isolated and cultivated in BG11, Z8, and BBM media to determine optimal growth conditions. Cytotoxic effects of extracts/compounds were determined using the sulforhodamine B assay on human lung cancer (SK-LU-1) and human liver cancer (HepG2) cell lines. The methanol extract was partitioned with n-hexane and CH₂Cl₂, followed by extensive chromatographic separation and HPLC purification to afford twelve compounds, including two new and ten known compounds. The structures were elucidated by HR-ESI-MS and NMR spectra, chemical methods, and comparing compounds in the literature. Results: From the phytoplankton samples collected across six freshwater bodies in Hue city, Vietnam, thirteen microalgal strains were successfully isolated and purified under laboratory conditions. These strains were morphologically and taxonomically identified to be Microcystis aeruginosa HU05, Microcystis viridis HU13, Anabaena circinalis HU08, Aphanizomenon flos-aquae HU02, Dolichospermum smithii HU04, Calothrix braunii HU14, Nostoc muscorum HU12, Nostoc punctiforme HU11, Raphidiopsis raciborskii HU03, Lyngbya spiralis HU15, Planktothrix stagnina HU16, Phormidium subtilis HU06, and Scenedesmus quadricauda HU07. All methanol extracts of those microalgae were evaluated for cytotoxic activity. The MeOH extracts of M. viridis (HU13) and D. smithii (HU04) exhibited significant cytotoxic effects, with IC₅₀ values of 6.19 ± 0.80 and 4.89 ± 0.76 µg/mL for M. viridis, and 9.51 ± 0.84 and 8.32 ± 0.94 µg/mL for D. smithii against SK-LU-1 and HepG2 cell lines, respectively. Furthermore, chemical studies of D. smithii HU04 led to the isolation of two new compounds, smithioside A (1) and smithioside B (2) and ten known ones, 3,4,5-trimethoxyphenyl-1-O-β-D-glucopyranoside (3), 4′-hydroxy-3′-methoxyphenol-β-D-[6-O-(4″-hydroxy-3″,5″-dimethoxylbenzoate)]-glucopyranoside (4), 4′-hydroxy-2′,6′-dimethoxyphenol 1-O-β-D-(6-O-syringoyl)glucopyranoside (5), mallophenol B (6), pisoninol II (7), guaiacylglycerol (8), (E)-asarone (9), deacetylsarmentamide B (10), (E)-2-hexenyl-β-D-glucopyranoside (11), and 5,6-dihydropyridin-2(1H)-one (12). The cytotoxic activity of all isolated compounds was also evaluated against SK-LU-1 and HepG2 cancer cell lines. Compound 12 showed the strongest activity, with IC₅₀ values of 9.13 ± 0.89 µM (SK-LU-1) and 7.64 ± 0.46 µM (HepG2). Compounds 5 and 6 exhibited moderate cytotoxic activity on both human cancer cell lines with IC₅₀ values ranging from 25.99 to 51.47 µM. Conclusions: These results highlight the potential of Dolichospermum smithii HU04 as a source of bioactive compounds, particularly in anticancer applications. These findings suggest that D. smithii HU04 extracts could be developed for therapeutic purposes targeting cancer. Full article