Search Results (401)

Chlorella vulgaris is a microalga with well-established nutritional, antioxidant, anti-inflammatory, and antibacterial potential. The current study aimed to explore the green synthesis of silver nanoparticles (AgNPs) using the ethanolic extract of C. vulgaris and to assess how nanoparticle formation affects the chemical composition, antimicrobial potential, antioxidant capacity, and spasmolytic activity of the extract, building on earlier evidence for its modulatory effects on gastrointestinal smooth muscle. Even though AgNPs from Chlorella have been obtained previously, to the best of our knowledge, their spasmolytic activity has not been evaluated. To assess their properties and stability, ATR-FTIR, TEM images, XRD, DLS, and zeta potential were used. The obtained AgNPs were mostly spherical (with a diameter between 10 and 50 nm) and showed good colloidal stability. The synthesis of AgNPs resulted in significant changes in lipid composition, pigment content, and fatty acid profiles, including a decrease in total chlorophylls and an increase in mono- and polyunsaturated fatty acids. The biosynthesized AgNPs showed moderate to strong antibacterial activity against a variety of Gram-positive and Gram-negative bacteria, yeasts, and fungi. The most pronounced inhibitory effect was observed against A. niger and P. chrysogenum. In ex vivo organ bath experiments, AgNPs modulated the contractile activity and the spasmolytic profile of isolated rat gastric smooth muscle compared with C. vulgaris extract. These results demonstrate that green-synthesized AgNPs present systems with altered smooth muscle activity and improved antibacterial qualities, underscoring their potential for use in functional foods, nutraceuticals, and gastrointestinal therapeutics. Full article

Antimicrobial resistance (AMR) is a major global health concern, which complicates treatment of microbial infections and wounds. Conventional therapies are no longer effective against drug resistant microbes; hence, novel antimicrobial approaches are urgently required. Silver nanoparticles (AgNPs) offer stronger antimicrobial activity, and in situ synthesis improves stability, uniformity, cost efficiency, and bioactivity while minimising contamination. These features make AgNPs well-suited for incorporation into textiles and wound dressings. Red wine extract (RW-E), rich in antioxidant and anti-inflammatory compounds was used to hydrothermally synthesise RW-AgNPs and RW-AgNPs-loaded on cotton (RWALC) by optimising pH and RW-E concentration. Characterisation was performed using UV–Vis spectroscopy, dynamic light scattering (DLS), and High Resolution and Scanning electron microscopy (HR-TEM and SEM). Antibacterial activities were evaluated against human pathogens through agar disc diffusion assay for RWALC and microdilution assay for RW-AgNPs. RWALC showed higher potency against both Gram-negative and Gram-positive bacteria, with inhibition zones of 12.33 ± 1.15 to 23.5 ± 5.15 mm, that surpassed those of ciprofloxacin (10 ± 3 to 19.17 ± 1.39 mm at 10 μg/mL). RW-AgNPs exhibited low minimum inhibitory concentrations (MIC: 0.195–3.125 μg/mL) and minimum bactericidal concentrations (MBC: 0.78–6.25 μg/mL). Preincubation with β-mercaptoethanol (β-ME) inhibited the antibacterial activity of RWALC, suggesting that thiolated molecules are involved in AgNPs-mediated effects. This study demonstrated that green-synthesised RW-AgNPs, incorporated in situ into cotton, conferred strong antibacterial properties, warranting further investigation into their mechanisms of action. Full article

Herein, we report the synthesis, characterization, and catalytic evaluation of cobalt hydroxide chloride [Co₂(OH)₃Cl] in the solvent-free synthesis of 2-substituted 2,3-dihydroperimidines. The presented method aligns with several green chemistry principles, offering operational simplicity, purification by recrystallization, no by-product formation, high yields (64–99%), and short reaction times. A total of 16 dihydroperimidines were synthesized to demonstrate substrate scope versatility. Additionally, the catalyst was successfully recycled and reused in multiple cycles without significant loss. Its robustness was further confirmed by gram-scale synthesis, achieving an 89% yield. Full article

Yellow Mosaic Disease (YMD) caused by mungbean yellow mosaic virus (MYMV, begomovirus) is one of the main causes of low mungbean (Vigna radiata L.) productivity, primarily in South Asia. Agroinoculation screening for MYMV resistance in mungbean cultivar VGGRU 1, an interspecific derivative of mungbean × rice bean and VRM (Gg)1 across replications, revealed VGGRU1 as highly resistant to MYMV infection. Gas chromatography mass spectrometry analysis was performed on the methanolic leaf extracts of susceptible and resistant genotypes, along with necessary controls. The metabolite profiling of the susceptible and resistant genotypes, along with controls, identified 121 discriminant metabolites belonging to 24 different classes of metabolites. A maximum number of 27 metabolites were accumulated in agroinoculated VGGRU1 alone. Metabolite profiles of VGGRU1 and VRM1 were clustered hierarchically and revealed substantial variations between the genotypes. Fold change revealed the upregulation of amino acids and phenol in the resistant genotype. The resistant genotype, VGGRU1, showed significantly higher levels of key defense-related metabolites, such as amino acids and phenolics. In this study, 18 significant VIP metabolites were identified, differentiating the resistant VGGRU1 and susceptible VRM (Gg)1 genotypes. Full article

This study conducted a comprehensive comparison of two green extraction methods, microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE), for recovering bioactive phenolic compounds from Pinus pinaster bark. The goal was to valorize timber industry waste and enhance the value of by-products through the development of eco-friendly processes to extract phenolic compounds from Pinus pinaster Aiton subsp. atlantica in northwest Portugal. MAE achieved significantly higher extraction yields than UAE (11.13 vs. 3.47 g extract/100 g bark) and superior total phenolic content (833 vs. 514 mg GAE/g). MAE extracts also exhibited enhanced antioxidant activity in most assays tested (DPPH, ABTS, ORAC, and OxHLIA), while both extracts effectively inhibited lipid peroxidation (TBARS) and showed activity against Gram-positive bacteria. Phenolic profile analysis revealed that MAE recovered a substantially higher amount of total phenolic compounds (230.0 mg/g) compared to UAE (86.95 mg/g), with procyanidins identified as the predominant compounds. The greater recovery of this complex procyanidin mixture by MAE is strongly associated with the enhanced bioactivities observed. Overall, this study confirms MAE as a highly efficient and sustainable technology for transforming pine bark waste into valuable antioxidant and antimicrobial extracts with potential applications in the food and pharmaceutical industries. Full article

Rare-earth oxide (REO) nanoparticles (NPs)—such as cerium (CeO₂), samarium (Sm₂O₃), neodymium (Nd₂O₃), terbium (Tb₄O₇), and praseodymium (Pr₂O₃)—have demonstrated strong antimicrobial activity against multidrug-resistant bacteria. Their effectiveness is attributed to unique physicochemical properties, including oxygen vacancies and redox cycling, which facilitate the generation of reactive oxygen species (ROS) that damage microbial membranes and biomolecules. Additionally, electrostatic interactions with microbial surfaces and sustained ion release contribute to membrane disruption and long-term antimicrobial effects. REOs also inhibit bacterial enzymes, DNA, and protein synthesis, providing broad-spectrum activity against Gram-positive, Gram-negative, and fungal pathogens. However, dose-dependent cytotoxicity to mammalian cells—primarily due to excessive ROS generation—and nanoparticle aggregation in biological media remain challenges. Surface functionalization with polymers, peptides, or metal dopants (e.g., Ag, Zn, and Cu) can mitigate cytotoxicity and enhance selectivity. Scalable and sustainable synthesis remains a challenge due to high synthesis costs and scalability issues in industrial production. Green and biogenic routes using plant or microbial extracts can produce REOs at lower cost and with improved safety. Advanced continuous flow and microwave-assisted synthesis offer improved particle uniformity and production yields. Biomedical applications include antimicrobial coatings, wound dressings, and hybrid nanozyme systems for oxidative disinfection. However, comprehensive and intensive toxicological evaluations, along with regulatory frameworks, are required before clinical deployment. Full article

Lipid peroxide (LPO) accumulation and a depletion of intracellular antioxidants are hallmarks of ferroptosis, a controlled iron-dependent form of cell death. Iron chelators and radical scavengers can stop it, while erastin or iron overload can cause it. The main catechin in green tea extract (GTE), epigallocatechin-3-gallate (EGCG), has iron-chelating and antioxidant activities. Herein, we investigated the effects of EGCG-rich GTE on ferroptosis in iron-loaded hepatocytes. The contents of EGCG, total phenolics (TPC), and flavonoids (TFC), as well as ABTS^•+-scavenging activity and cytotoxicity, were determined. Human hepatoma (Huh7) cells were treated with ferric ammonium citrate (FAC) to induce ferroptosis and were co-treated with various concentrations of GTE. Labile iron pool (LIP), reactive oxygen species (ROS), LPO, glutathione (GSH), and glutathione peroxidase 4 (GPX-4) activity were then measured in the cells. One gram of GTE contained 26 mg of EGCG, with a TPC of 172.2 mg gallic acid equivalents and a TFC of 32.9 mg quercetin equivalents. GTE displayed concentration-dependent ABTS^•+-scavenging activity (IC₅₀ = 1.03 mg) that was equivalent to 0.29 mg of Trolox, reporting a Trolox-equivalent antioxidant capacity (TEAC) value of 0.29 mg. High-dose GTE (>100 µM EGCG equivalent) reduced cell viability below 80% (p < 0.05). Intracellular LIP, ROS, and LPO levels were markedly elevated, whereas GSH and GPX-4 activity levels were decreased (p < 0.05) in iron-loaded Huh7 cells. GTE treatment mitigated these alterations in a dose-dependent manner (p < 0.05). These cell-based in vitro findings indicate that EGCG-rich GTE can attenuate ferroptosis-associated oxidative stress in hepatocytes under iron-loading conditions. GTE may serve as a potential dietary antioxidant candidate; further mechanistic studies and in vivo experiments are required to determine its physiological relevance and translational applicability. Full article

In the present study, alginate–silver nanoparticle (Alg-AgNP) nanocomposite hydrogels possessing antibacterial activity were synthesized via an innovative route. A task-specific designed Natural Deep Eutectic Solvent (NADES), composed of glucose, lactic acid, and water, was utilized as a green extraction solvent of bioactive compounds from olive leaves (OLs). The NADES–olive leaf extract (NADES-OLE) was used as obtained for the preparation of the Alg-AgNP nanocomposite hydrogel as a multiple-role component. The NADES-OLE acts (a) as a crosslinking agent for the preparation of the alginate hydrogels, (b) as a reducing agent for the in situ synthesis of AgNPs during hydrogel formation, and (c) as a bioactivity enhancement agent due to the presence of compounds obtained from the olive leaves. The Alg-AgNP hydrogel preparation process was optimized through a Box–Behnken experimental design. The resulting nanocomposite hydrogels were characterized for their swelling capacity and water retention in phosphate buffer (pH 5.5), achieving 538% swelling capacity within 180 min and 90% water retention after 250 min. The AgNPs formed within the hydrogels were found to have an average size of 103.2 ± 5.6 nm, with a concentration of 1.2 10⁸ ± 2.2 ∗ 10⁷ particles/mL. Antibacterial testing of the nanocomposite hydrogels against foodborne pathogens, including Gram-negative (Escherichia coli, Salmonella Typhimurium, Yersinia enterocolitica) and Gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus), revealed significant antibacterial activity, particularly against E. coli (64.9%), Y. enterocolitica (60.6%), S. aureus (79.1%), and B. cereus (55.3%), at a concentration of 1 mg/mL. Full article

Celtis africana, a rare plant native to southwestern Saudi Arabia, was explored for the first time as a source for the green synthesis of silver nanoparticles (AgNPs). Catechol-bearing phenolic amides in the aqueous leaf extract acted as both reducing and capping agents, enabling eco-friendly AgNP fabrication. The synthesized AgNPs were characterized using SEM, TEM, XRD, UV-Vis, and FTIR, revealing predominantly spherical nanoparticles with an average size of 9.28 ± 0.11 nm, a face-centered cubic crystalline structure, and a pronounced surface plasmon resonance at 424 nm. HPLC analysis confirmed the presence of caffeoyltryamine in the extract, while UV-Vis and FTIR indicated its attachment to the AgNP surface. The AgNPs exhibited broad-spectrum antimicrobial activity against Gram-positive bacteria (S. aureus, MRSA and E. faecalis) and Gram-negative bacteria (E. coli, K. pneumoniae, S. typhimurium, and P. aeruginosa), as well as pathogenic fungi such as C. albicans, C. glabrata, C. parapsilosis, and C. krusei with performance comparable to or exceeding that of AgNPs from Artemisia vulgaris, Moringa oleifera, and Nigella sativa. The MIC and MBC values for S. aureus, MRSA, E. coli, and S. typhimurium were consistently 6.25 µg/mL and 25 µg/mL, respectively, reflecting strong inhibitory and bactericidal effects at low concentrations. MTT assays demonstrated selective cytotoxicity, showing higher viability in normal human skin fibroblasts (HSF) than in MCF-7 breast cancer cells. The AgNPs also displayed strong antioxidant activity (IC₅₀ = 5.41 µg/mL, DPPH assay) and efficient catalytic reduction of 4-nitrophenol (4-NP) and methylene blue (MB), with rate constants of 0.0165 s⁻¹ and 0.0047 s⁻¹, respectively, exceeding most reported values. These findings identify Celtis africana as a promising source for eco-friendly AgNPs with strong antimicrobial, antioxidant, and catalytic properties for broad biological and environmental applications. Full article

An efficient and sustainable electrochemical method for [4+2] and [2+2] cycloadditions has been developed, enabling the facile synthesis of six- and four-membered carbocycles. This metal-free strategy leverages constant-current electrolysis to generate key radical cation intermediates in situ from electron-rich olefins, eliminating the need for stoichiometric oxidants or transition-metal catalysts. The reaction demonstrates broad compatibility with various cyclopentadiene and styrene derivatives, constructing complex bicyclic frameworks with high efficiency and selectivity. Notably, the practicality of this protocol is demonstrated by its gram-scale implementation. A portion of the desired product could be isolated in good yield simply by filtration, avoiding the need for column chromatography. This work establishes electrosynthesis as a powerful and scalable alternative to conventional thermal and photochemical strategies, aligning with the principles of green chemistry. Full article

This study focuses on optimizing the photochemical degradation of methylene blue (MB) using calcium-functionalized zinc oxide–copper oxide–alginate (ZnO/CuO/Alg) nanocomposite hydrogel beads under sunlight irradiation. Pure ZnO and CuO nanoparticles (NPs) were synthesized via a green co-precipitation method employing plant extracts and were subsequently embedded into an alginate polymer matrix. Various characterization techniques, including powder X-ray diffraction (PXRD), ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray analysis (SEM–EDX), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA), were employed to analyze the structure and morphology of the catalysts. The photocatalytic performance of the nanocomposites was evaluated by studying the effects of pH, catalyst dose, irradiation time and MB concentration. Mathematical modeling was used to determine the optimal degradation conditions, achieving a maximum photocatalytic efficiency of 77.86% under the following parameters: MB concentration of 20 mg/L, catalyst dose of 50 mg, irradiation time of 75 min and pH 8. The model fit the experimental data well, showing a coefficient of determination (R²) of 0.963, confirming its reliability. Additionally, the antibacterial potential of the nanocomposite powders was investigated. Tests were conducted using equal concentrations of pure ZnO, ZnO/CuO and ZnO/CuO/Alg nanocomposites on Petri dishes inoculated with both Gram-positive and Gram-negative bacterial cultures. The results revealed significant bacterial growth inhibition, with the ZnO/CuO/Alg nanocomposite exhibiting the largest inhibition zone of 20 mm, compared to 14 mm for pure ZnO, indicating superior antibacterial efficacy. Full article

Novel green solvents are a key focus in green chemistry, and deep eutectic solvents (DESs) are promising sustainable solvents. This study systematically examined the physicochemical properties (water content, polarity, conductivity, Kamlet-Taft parameters, and viscosity) of ten carboxylic acid-based DESs (CADESs). It also evaluated their antibacterial activity against representative Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The antibacterial activity of CADESs is closely related to low pH values, hydrogen bond donor properties, and the destructive effect on bacterial cell membranes. antioxidant properties via ABTS, DPPH scavenging assays and Fe²⁺ chelating assays, and phytotoxicity through mung bean tests. When used to extract flavonoids from walnut peel, the choline chloride/levulinic acid system with 30% water achieved the highest yield of 112.8 mg RE·g⁻¹ DW. Therefore, CADESs show great potential as green solvents for flavonoid extraction in sustainable technologies. Full article

Background: The golden era of antibiotics has long passed, and the clinical failures caused by emerging drug-resistant bacteria have intensified the demand for novel antimicrobial agents. Antimicrobial peptides have attracted significant attention as promising candidates for next-generation antibiotics. Methods: In this study, we identified a novel antimicrobial peptide, Caerin 1.1-LC, from the skin secretion of the Australian green tree frog, Litoria caerulea. Subsequent structure–activity relationship studies led us to design a series of analogues and revealed the critical role of the peptide’s intrinsic hinge structure in shaping its biological activity. Results: Incorporation of D-isomers at the valine residues within the hinge preserved overall helical content but altered the hinge conformation, resulting in an 8-fold increase in antibacterial activity against Gram-negative bacteria. Simultaneously, haemolytic activity was markedly reduced, leading to a 56-fold improvement in therapeutic index (from 0.47 to 26.6). Structural modulation of the hinge also switched the mechanism of action from classical membrane disruption with associated permeability changes to a non-membrane-permeabilising, ‘cell-penetrating-like’ behaviour, inducing membrane potential depolarisation and ATP disruption to trigger bacterial death. In vivo studies using infected larval models, along with in vitro LPS neutralisation assays, further demonstrated the therapeutic potential of the D-analogue as a novel antibacterial agent. Conclusions: This work highlights the pivotal role of hinge structures in Caerin-family/hinge-containing AMPs, offering a strategic avenue for optimising antibacterial efficacy. Full article

This study reports the solvent-free mechanochemical synthesis of a novel series of 2-hydrazone-bridged benzothiazole derivatives 19–52 via the reaction of 2-hydrazinylbenzothiazole derivatives 4–6 with O-alkylated benzaldehydes 7–18. The stereostructure of the E-isomers was confirmed by 2D NOESY spectroscopy. The antiproliferative potential of these newly prepared 2-hydrazone derivatives of benzothiazole 19–52 was evaluated in vitro against eight human cancer cell lines. Several compounds demonstrated low micromolar IC₅₀ values, with some outperforming the reference drug etoposide. Among the most potent compounds, the 6-chloro-2-hydrazone(3-fluorophenyl)benzothiazole derivative 38 exhibited remarkable activity against pancreatic adenocarcinoma (Capan-1, IC₅₀ = 0.6 µM) and non-small cell lung cancer (NCI-H460, IC₅₀ = 0.9 µM). Structure–activity relationship analysis revealed that derivatives 45–52, featuring a methoxy group at position 6 of the benzothiazole ring and either a methoxy or fluorine substituent at position 3 of the phenyl ring, showed consistently strong antiproliferative effects across all tested cell lines (IC₅₀ = 1.3–12.8 µM). Furthermore, compounds bearing N,N-diethylamino or N,N-dimethylamino groups at position 4 of the phenyl ring generally exhibited superior activity compared to those with morpholine or piperidine moieties. However, as this study represents an initial screening, further mechanistic investigations are required to confirm specific anticancer pathways and therapeutic relevance. In addition to their in vitro anticancer properties, the antibacterial activity of the compounds was assessed against both Gram-positive and Gram-negative bacteria. Notably, compound 37 demonstrated selective antibacterial activity against Pseudomonas aeruginosa (MIC = 4 µg/mL). Overall, this work highlights the efficiency of a green, mechanochemical approach for synthesizing E-isomer hydrazone-bridged benzothiazoles and underscores their potential as promising scaffolds for the development of potent antiproliferative agents. Full article

The need for new strategies to reduce the susceptibility of polymeric materials to bacterial colonization is growing, especially with the emergence of drug-resistant bacterial strains. Antimicrobial agents used to modify polymers should not only be effective against microorganisms in both planktonic and biofilm states but also be safe and environmentally friendly. Phytochemicals, which are components of essential oils, may be a suitable choice to help combat microbial resistance to antibiotics. Furthermore, they meet the requirements of green chemistry. Essential oils synthesized by plants as secondary metabolites are capable of combating both Gram-positive and Gram-negative bacteria by disrupting lipid bilayers, affecting efflux pumps, compromising the integrity of bacterial cell membranes, and inhibiting the quorum-sensing system. They are also effective as adjuvants in antibiotic therapies. In this review, we outline the mechanism of action of various essential oil components that resulted in enhanced eradication of planktonic bacteria and biofilms. We summarize the use of these antimicrobial agents in macromolecular systems (nanovessels, fibers, nanocomposites, and blends) and provide an overview of the relationship between the chemical structure of phytochemicals and their antimicrobial activity, as well as their influence on the properties of polymeric systems, with a special focus on green active packaging materials. Full article