Search Results (668)

Saturated and branched high molecular weight organic esters are highly valued as emollients in the cosmetic industry due to their superior properties. Their saturated character provides resistance to oxidation and rancidity. Additionally, their branched structure endows them with low melting temperatures, enabling them to remain liquid over a broad temperature range. These esters can be obtained from branched alcohols, branched fatty acids or both, using chemical or enzymatic processes. Among branched alcohols, Guerbet alcohols stand out. Due to their characteristic properties as branched, saturated alcohols with superior oxidative stability and extremely low volatility, they are proposed as excellent substrates for the enzymatic synthesis of these compounds. This study represents the first investigation into the biocatalytic synthesis of three specific esters: those formed between 2-octyl-1-dodecanol (C20 Guerbet alcohol) and the fatty acids myristic (MA), palmitic (PA), and stearic acid (SA). To achieve this, an environmentally sustainable biocatalytic process was developed. The synthesis involves a solvent-free esterification catalyzed by the commercial immobilized lipase, Lipozyme^® 435, conducted within a vertically stirred, thermostated batch tank reactor. Optimal conditions for lipase concentration and temperature were established, and the sustainability of the process was successfully quantified using various “green metrics”. Full article

The cashew apple (Anacardium occidentale L.) is rich in antioxidant bioactive constituents that have anti-aging and wound healing properties. The objective of this study is to evaluate the biological activities of cashew apple extract (CAE) and to improve the issue involving the instability of ascorbic acid, the principal active compound, by encapsulating the extract in liposomes in order to enhance its stability and skin permeation for cosmetic applications. CAE was obtained from fresh cashew apple via ethanol maceration, solvent evaporation, and freeze-drying. Ascorbic acid content, total phenolic content (TPC), total flavonoid content (TFC), and total caffeoylquinic acid content (TCQAC) were determined. The ascorbic acid content and its tautomer in the extract were quantified using the LC-MS/MS method. Biological activities, including antioxidant, anti-tyrosinase, fibroblast collagen synthesis, cytoprotection against oxidative stress, wound healing, and cytotoxicity, were assessed. CAE was encapsulated in liposomes to enhance the stability of its inherent ascorbic acid and improve its skin in comparison to free-CAE. The CAE and liposomal-CAE were incorporated and formulated into a solution, and their physicochemical stability was assessed after storage. CAE appeared as a brown, viscous liquid with a characteristic sweet, fruity scent. Each gram of CAE contained 0.90 ± 0.05 mg of ascorbic acid, TPC, 81.40 ± 7.14 mg of gallic acid equivalents (GAE), TFC, 3.73 ± 0.30 mg of rutin equivalents (RE), and TCQAC, 4.48 ± 0.05 mg of chlorogenic acid equivalents (CGAE). CAE exhibited antioxidant properties (IC₅₀ = 282.19 ± 11.16 and 963.66 ± 3.95 µg/mL for DPPH and ABTS assay, respectively) and weak anti-tyrosinase activity (IC₅₀ = 4213.77 ± 138.97 µg/mL). It was non-cytotoxic to fibroblast and monocyte cells at a concentration of less than 1 mg/mL. In vitro wound healing assays demonstrated that CAE stimulated collagen production in a dose-dependent manner at CAE concentrations above 250 µg/mL. Additionally, CAE exhibited cytoprotective effects against H₂O₂-induced oxidative stress and did not induce inflammatory responses in immune cells. The liposomal formulation containing CAE achieved high encapsulation efficiency (79.75–84.55%) based on ascorbic acid content. In skin permeation studies, CAE-loaded liposomes demonstrated an enhancement ratio approximately two-fold greater than that of free-CAE. Stability testing over 3 months showed that the ascorbic acid content in CAE-loaded liposomes remained significantly higher than that in the free-CAE under both refrigerated and long-term conditions (30 °C/75% RH). CAE demonstrated potential anti-aging properties for improving aging skin. Liposomal incorporation markedly improved ascorbic acid stability and skin permeability. Full article

Manganese complexes of the general formula [Mn(DAB)(CO)₃Br] featuring sterically demanding α-diimine ligands (DAB) were prepared, characterized, and found to be catalytically active in the hydroboration of ketones. The developed eco-friendly approach allowed straightforward formation of boronic esters in quantitative yields in mild and solvent-free conditions. Full article

A solvent-free, solid-state mechanochemical method was developed to synthesize the chalcohalide compound SbSI at room temperature. Dry high-energy planetary ball milling of elemental antimony, sulfur, and iodine produced a pure, stoichiometric polycrystalline SbSI powder with an orthorhombic structure. This powder was then sintered under mild thermal conditions to create dense targets. Amorphous SbSI thin films were subsequently deposited from these targets at room temperature using Pulsed Electron Deposition. The films maintained the correct stoichiometry and exhibited an optical bandgap of 1.89 eV. Post-deposition annealing at 90 °C in air successfully induced crystallization, demonstrating a viable, low-temperature, and eco-friendly route to produce polycrystalline SbSI thin films. This scalable approach has promising potential for optoelectronic and energy-harvesting applications. Full article

Electrospun fibers serve as a medium for the targeted release of active compounds, facilitating the desired therapeutic effects in drug administration. The point of this study was to find the best conditions for making electrospun fibers from cellulose acetate (CA) and poly(ε-caprolactone) (PCL), mixed with pure oxyresveratrol extract from Artrocarpus lakoocha Roxberg (Moraceae). Additionally, the study focused on evaluating the antioxidant properties, antityrosinase activity, and freeze–thaw stability of the resulting fibers. We incorporated a concentration of oxyresveratrol at 0.1% w/w into various mass ratios of CA/PCL blended fiber sheets (1:0, 3:1, 1:1, 1:3), utilizing mixed solvents of acetone/DMF (2:1% v/v) and chloroform/DMF (9:1% v/v) for preparation. The fiber sheets displayed a continuous and uniform structure, with fiber diameters ranging from 300 to 1000 nanometers. We investigated the release kinetics of oxyresveratrol from the fibrous substrates using the total immersion technique, specifically in phosphate-buffered saline at a pH of 7.4. The results showed that the fiber sheet with a 3:1 w/w ratio of CA to PCL and a 0.1 w/w loading of oxyresveratrol showed the most significant release of oxyresveratrol at the 2 h mark, and it continued to release consistently at this peak value for up to 24 h. The antioxidant and anti-tyrosinase properties of oxyresveratrol in fiber sheets were more stable than those of free oxyresveratrol at the same concentrations. The fiber sheet presents a promising avenue for a user-friendly transdermal patch application. Full article

The growing demand for sustainable and efficient synthetic methodologies has brought nanocatalysis to the forefront of modern organic chemistry, particularly in the construction of heterocyclic compounds through multicomponent reactions (MCRs). Among various nanocatalysts, calcium oxide nanoparticles (CaO NPs) have gained significant attention because of their strong basicity, thermal stability, low toxicity, and cost-effectiveness. This review provides a comprehensive account of the recent strategies using CaO NPs as heterogeneous catalysts for the green synthesis of nitrogen- and oxygen-containing heterocycles through MCRs. Key reactions such as Biginelli, Hantzsch, and pyran annulations are discussed in detail, with emphasis on atom economy, reaction conditions, product yields, and catalyst reusability. In many instances, CaO NPs have enabled solvent-free or aqueous protocols with high efficiency and reduced reaction times, often under mild conditions. Mechanistic aspects are analyzed to highlight the catalytic role of surface basic sites in facilitating condensation and cyclization steps. The performance of CaO NPs is also compared with other oxide nanocatalysts, showcasing their benefits from green metrics evaluation like E-factor and turnover frequency. Despite significant progress, challenges remain in areas such as asymmetric catalysis, industrial scalability, and catalytic stability under continuous use. To address these gaps, future directions involving doped CaO nanomaterials, hybrid composites, and mechanochemical approaches are proposed. This review aims to provide a focused and critical perspective on CaO NP-catalyzed MCRs, offering insights that may guide further innovations in sustainable heterocyclic synthesis. Full article

A novel Ag(I) coordination polymer, [Ag₂(bipy)(btca)]_n, (SCP 1) was synthesized using 4,4′-bipyridyl (bipy) and 1,2,4,5-benzene-tetracarboxylic acid (H₄BTC). Characterization by FT-IR, ¹H/¹³C NMR, and single-crystal X-ray diffraction confirmed its 3D network structure. The structure of SCP 1 consists of two chains arranged in …ABAB… fashion. Chain A is one-dimensional, containing [Ag(4,4′-bipy)]_n chain, while chain B is free, containing uncoordinated 1,2,4,5-benzene tetracarboxylate and water molecules. The stacking and argentophilic interactions extend the chain A of [Ag(4,4′-bipy)]_n into a two-dimensional layer. In contrast, chain B of uncoordinated 1,2,4,5-benzene tetracarboxylate and water molecules form a 1-D chain through extensive hydrogen bonds between water molecules and BTC ions and between water molecules themselves. Chains A and B are connected through extensive hydrogen bonds, generating a three-dimensional network structure. This Silver I supramolecular coordination polymer (SCP 1) demonstrated high catalytic activity as a recyclable heterogeneous catalyst for the synthesis of 5-substituted 1H-tetrazoles via [3+2] cycloaddition of NaN₃ and terminal nitriles under solvent-free conditions in a Q-tube pressure reactor (yields: 94–99%). A mechanistic proposal involving cooperative Lewis acidic Ag(I) sites and Brønsted acidic -COOH groups facilitates the cycloaddition and protonation steps. SCP 1 catalyst exhibits reusability up to 4 cycles without significant loss of activity. The structural stability of the SCP 1 catalyst was assessed based on PXRD and FTIR analyses of the catalyst after usage, confirming its integrity during the recycling process. Full article

The search for bioactive compounds against chronic diseases such as cancer and diabetes includes curcuminoids as promising scaffolds. Here, we report the synthesis of a family of curcuminoid analogue compounds with an extended unsaturated central chain, as follows: difluoroboron complex 1, the enolised curcuminoid 2, and its homoleptic copper complex 3, in moderate to good yields (68–90%). Additionally, their β-cyclodextrin (BCD) association complexes, 4 and 5, were prepared through a mechanochemical method and characterised by spectroscopic techniques. Complete ¹H and ¹³C NMR assignments and NOESY correlations revealed unique solvent effects on the conformational disposition of compound 2, while the copper complex 3 displayed the highest extinction coefficient (1.20 × 10⁵ M⁻¹·cm⁻¹). Furthermore, the authentication of the polymorph of 1 and the new crystal structures of 2 and 3, determined by single-crystal X-ray analysis, were highlighted. Although the copper complex 3 initially exhibited the lowest a-glucosidase inhibitory activity (IC₅₀ > 100 µM), it showed a significant increase (IC₅₀ = 36.27 µM) upon association with BCD, reaching values comparable to the free ligand (IC₅₀ = 45.63 µM). Compounds 1–5 were non-toxic to healthy cells (COS-7), but compound 5 stands out as a promising candidate against this metabolic condition. Full article

Efficient biomass harvesting remains one of the primary barriers to the commercial feasibility of large-scale microalgal production. This study investigates the effect of different culture media on the surface physicochemical properties of Tetradesmus sp., with emphasis on their role in natural aggregation. Cultures were grown for 30 days under controlled light and temperature conditions using Blue Green 11 (BG11), Tris–acetate–phosphate (TAP), and deionized water supplemented with Bayfolan^® fertilizer. Surface hydrophobicity was assessed through microbial adhesion to solvents (MATS) and contact angle analysis, electrokinetic properties were evaluated by zeta potential measurements, and cell surface chemistry was characterized by attenuated total reflectance (ATR) sampling methodology for Fourier Transform Infrared (FTIR) spectroscopy. Across all treatments, Tetradesmus sp. exhibited inherent hydrophobicity, but Bayfolan^® supplementation yielded the highest contact angle (49.0 ± 0.9°) and the least negative free energy of interaction (ΔGsws = −26.36 mJ·m⁻²), indicating a stronger tendency toward self-aggregation. Zeta potential values remained consistently negative (−10 to −14 mV), with no significant variation among media, suggesting that hydrophobic interactions rather than electrostatic forces govern aggregation. ATR-FTIR spectra confirmed the presence of lipids, proteins, and carbohydrates, with changes in peak intensities reflecting metabolic adjustments to media composition. These results demonstrate that low-cost Bayfolan^® supplementation enhances surface hydrophobicity and aggregation, providing a sustainable strategy to facilitate biomass recovery and reduce harvesting costs in microalgal biorefineries. Full article

The hydrogenation of p-cymene to p-menthane, a bio-based solvent, over four platinum-group catalysts, was thoroughly investigated in this study. The effect of the support material, pressure, and temperature were explored. Rhodium was the most effective metal, even under normal pressure conditions. Charcoal was a better metal support compared to alumina, offering better selectivity at lower pressure and outstanding recyclability. Hydrogen pressure had no effect on the selectivity; however, the conversion rate was maximal at higher pressure. At higher temperatures, the thermodynamically stable trans-isomer was favored, whereas at lower temperatures the cis-isomer became predominant. Remarkably, Rh/C achieved >99% conversion of p-cymene and maintained stable activity and selectivity over 66 recycling cycles, whereas the same metal-based catalyst on alumina was only recycled twice. These findings demonstrate that the solvent-free hydrogenation of p-cymene can be efficiently achieved using commercially available catalysts, with Rh/C emerging as a promising benchmark for sustainable and green catalytic processes. Full article

Use of a microwave-labile leaving group, 2,4-dinitrophenyl (2,4-DNP), leads to O-glycosylation in 70–80% yields with high α-selectivity. The 2,4-DNP glycosyl donors, protected with electron-donating benzyl ethers, gave the best results under controlled microwave conditions, which were all conducted in polar aprotic solvents, such as DMF, and were all conducted in the absence of any reagent-activating additives such as a Lewis acid/base or Brønsted–Lowry acid/base. This method represents concerted efforts towards reagent-free neutral glycosylation. Full article

Brønsted acid-catalyzed, regiodivergent hydroindolation of indoles with terminal aryl alkynes was developed, affording bis(indolyl)alkanes in good to excellent yields. Systematic investigations revealed that temperature variation plays a key role in determining the regioselectivity of anti-Markovnikov and Markovnikov addition reactions. The reaction proceeds efficiently under transition metal-free conditions in an environmentally benign water/alcohol solvent system, using readily available and inexpensive p-toluenesulfonic acid (TsOH) as the catalyst. Control experiments and mechanistic studies support distinct reaction pathways for each regioisomer. Full article

Miscanthus × giganteus particles possess excellent advantages in biodegradability and sustainability. However, their susceptibility to ultraviolet (UV) degradation limits wider outdoor applications. In the present work, electron beam (e-beam) radiation-induced grafting was used for the first time to attempt covalent grafting of UV absorbers onto miscanthus particles to address a major challenge in natural fiber stabilization. Two UV absorbers, 2-hydroxy-4-(methacryloyloxy) benzophenone (HMB) and 2-(4-benzoyl-3-hydroxyphenoxy) ethyl acrylate (BHEA), were explored using both pre-irradiation and simultaneous approaches. Pre-irradiation grafting did not achieve useful covalent fixation of HMB or BHEA, due in part to the premature decay of radicals at elevated temperatures and with solvent use, and the lignin-based quenching of radicals. Solvent-free mutual irradiation grafting failed due to immobility of the UV absorbers, while grafting of HMB in solvent failed due to radical-scavenging behavior. Grafting of BHEA was successfully achieved under solvent-based simultaneous irradiation, reaching up to 38 wt % DG in a butanone/2.5% H₂SO₄ system. This condition led to the improved UV stability of miscanthus particles, in which color change was reduced significantly after 1000 h of accelerated weathering; this was mainly linked to a beneficial pre-darkening effect which was induced by the presence of the acid. This work proposes a route of grafting strategy that aims to improve the photostability of miscanthus particles, paving the way for durable bio-based materials in outdoor composite applications. Full article

This study aimed to investigate the molecular binding mechanisms of bromocriptine toward histamine-associated targets, exploring both antagonist-like and other potential interaction modes that may support therapeutic repurposing. Network pharmacology was applied to identify histamine-related pathways and prioritize potential protein targets. CXCR4, GHSR, and OXTR were selected based on combined docking scores and pharmacophore modeling evidence. Molecular dynamics (MD) simulations over 100 ns assessed structural stability, flexibility, compactness, and solvent exposure. Binding site contact analysis and MM/PBSA free binding energy calculations were conducted to characterize binding energetics and interaction persistence. Bromocriptine exhibited stable binding to all three receptors, engaging key residues implicated in receptor modulation (e.g., Asp187 in CXCR4, Asp99 in GHSR, Arg232 in OXTR). The MM/PBSA ΔG_binding values of bromocriptine were −22.67 ± 3.70 kcal/mol (CXCR4 complex), −22.11 ± 3.55 kcal/mol (GHSR complex), and −21.43 ± 2.41 kcal/mol (OXTR complex), stronger than standard agonists and comparable to antagonists. Contact profiles revealed shared and unique binding patterns across targets, reflecting their potential for diverse modulatory effects. Bromocriptine demonstrates high-affinity binding to multiple histamine-associated GPCR targets, potentially exerting both inhibitory and modulatory actions. These findings provide a molecular basis for further experimental validation and therapeutic exploration in histamine-related conditions. Full article

A series of Zn complexes containing guanidine– and amidine–phenolate ligands were synthesized and evaluated as catalysts for the polymerization of rac-lactide at 130 °C, under solvent-free conditions, giving rate constants in the range of 0.71–4.37 × 10^–4 s^–1. Polymerization under identical conditions with the guanidine– and amidine–phenol proligands themselves used as catalysts gave values in the range of 0.30–2.45 × 10^–4 s^–1. The stereoselective production of polylactic acid from either the Zn complexes or the proligands was limited (P_r = 0.47–0.62). The molecular weight of the polymers was lower than expected for living polymerizations due to chain transfer and/or transesterification but were comparable to those obtained in control experiments with Sn(Oct)₂. Full article