Search Results (88)

Onion peel extract (OPE) is rich in polyphenolic compounds with antimicrobial potential. Salmonella Enteritidis (SE) infection in young broiler chicks causes morbidity, reduced growth, and contributes to human gastroenteritis through contaminated poultry products. The spleen is a key secondary lymphoid organ coordinating systemic responses to pathogens in chicken. This study evaluated how dietary OPE influences spleen metabolic profiles during SE infection. Day-old Ross 708 male chicks (n = 128) were assigned to four treatments: CON, CON-SE, OPE (6 g/kg), and OPE-SE. Chicks in CON and OPE received sterile broth, whereas CON-SE and OPE-SE received 2.25 × 10⁸ CFU/mL SE at 2 d of age. At 5 and 12 dpi, spleens from six chicks per treatment were collected for untargeted HPLC-MS metabolomics. A total of 857 metabolites were identified and analyzed using MetaboAnalyst 6.0 (p < 0.05; fold change ≥ 2.0; VIP score > 1.0). In CON-SE chicks, energy generating metabolites (6-phosphogluconic acid, methylmalonic acid, propionic acid) increased, while 13,14-dihydro-15-keto-prostaglandin D2 and kynurenic acid decreased. Dietary OPE elevated several dipeptides (L-Val-Gly, L-Leu-Gly, Gly-Gly-Leu, L-Val-L-Met) and reduced ATP linked metabolites (3,6-di-O-methyl-beta-D-glucose and 3-O-beta-D-galactosyl-sn-glycerol). Enrichment analysis showed that SE infection altered valine, leucine, and isoleucine degradation and aromatic amino acid biosynthesis, whereas OPE enriched galactose and biotin metabolism in uninfected chicks, but enriched tryptophan, taurine and hypotaurine metabolism in SE-infected chicks. Overall, dietary OPE optimized response of metabolic pathways associated with immune activation, unlike corresponding pathways in CON-SE birds. Full article

Breast cancer remains one of the most frequently diagnosed malignancies and a leading cause of cancer-related mortality among women worldwide. The growing interest in natural bioactive compounds has highlighted plant-derived phytochemicals as promising agents for cancer prevention and adjunctive therapy due to their pleiotropic biological activities and relatively low toxicity. In parallel, increasing attention has been directed toward agro-industrial by-products generated during food processing, which represent abundant and sustainable sources of valuable phytochemicals. This review provides a comprehensive overview of recent advances in the identification, extraction, and biological evaluation of phytochemicals derived from plants and agro-industrial residues, using pomegranate (Punica granatum) peels, onion (Allium cepa) skins, and citrus by-products as representative examples of phytochemical-rich agro-industrial residues. These by-products are rich in polyphenols, flavonoids, and other secondary metabolites—including punicalagins, ellagic acid, quercetin, hesperidin, and naringin—that have demonstrated significant antioxidant, anti-inflammatory, and anticancer properties. Recent in vitro and in vivo studies indicate that these compounds can modulate key molecular pathways involved in breast cancer initiation and progression, such as oxidative stress regulation, apoptosis induction, inhibition of cell proliferation, and suppression of signaling cascades including PI3K/Akt, NF-κB, and MAPK pathways. Furthermore, the valorization of agro-industrial waste offers a sustainable strategy to recover high-value bioactive compounds while reducing environmental impact. Overall, phytochemicals obtained from plant materials and food processing by-products represent promising functional agents for breast cancer prevention and therapy, although further studies are required to improve bioavailability, elucidate mechanisms of action, and validate their clinical potential. Full article

Yellow onion (Allium cepa L.) outer skins are a high-volume agricultural waste that can be converted into commercially valuable bioproducts using various extraction techniques. This research focused on optimizing a green ultrasound-assisted extraction (UAE) method which allows for the isolation of several phytochemicals valued for their health benefits, such as polyphenols and flavonoids. HPLC/UV analysis of the extracts showed that the main component was quercetin. A one-factor-at-a-time (OFAT) design was used to identify the extraction parameters needed in order to maximize the amount of extracted target phytochemicals. The polyphenols, flavonoids and quercetin contents, along with the antioxidant activity of the extracts, were optimized by response surface methodology using a Box–Behnken design. Ultrasound amplitude, ethanol concentration, and time were selected as the most appropriate variables. The final results showed that TPC ranged from 78.16 to 97.16 mg GAE/g DM, TFC ranged from 22.77 to 26.46 mg QE/g DM, while CUPRAC values varied between 145.24 and 163.75 mg TE/g DM. The optimal extraction conditions were determined using a Box–Behnken model as 30% ultrasound amplitude, 53% ethanol concentration, and an extraction time of 13 min. The use of these conditions allowed the TPC, TFC and CUPRAC to show predicted values of 97.8 mg GAE/g DM, 27.2 mg QE/g DM, and 159.8 mg TE/g DM, respectively. These findings indicate that onion skin extracts could represent a green and promising source of antioxidant phytochemicals. Full article

The X-ray occultation technique has emerged as a novel remote sensing method for probing planetary neutral atmospheres, complementing traditional radio and ultraviolet stellar occultations. This study evaluates the feasibility and effective altitude range of X-ray occultation for retrieving Martian atmospheric density. Using the Mars Climate Database (MCD) for atmospheric number density profiles and the XrayDB database for photoabsorption cross-sections, we calculate the X-ray transmittance as a function of tangent altitude for photon energies ranging from 0.25 keV to 20 keV. An onion-peeling ray-tracing model is employed to simulate the line-of-sight optical depth. The results indicate that X-ray photons in the soft to hard X-ray band (0.25–20 keV) are sensitive to the Martian atmosphere at altitudes between approximately 50 km and 160 km, bridging the gap between accelerometer measurements (surface to ∼50 km) and extreme ultraviolet (EUV) remote sensing (>100 km). This forward modeling framework provides a theoretical baseline for future X-ray occultation-based density retrieval in the Martian mid-atmosphere. Full article

Onion peel represents a valuable food by-product rich in bioactive phenolic compounds. Building on previous phytochemical investigations, an onion peel extract from the Rossadi Tropea variety was developed as a standardized bioactive ingredient (OPI-T), defined by flavonol (quercetin and its glycosylated and oxidized derivatives) and anthocyanin (cyanidin derivatives) markers, ensuring batch-to-batch consistency, and evaluated for its potential against hepatic steatosis. The present study aimed to assess the protective effects of OPI-T against palmitate-induced steatosis and oxidative stress in HepG2 cells, a widely used in vitro model of hepatic lipid accumulation. An onion peel extract derived from the Ramata di Montoro variety was included as a natural negative reference to account for varietal variability. HepG2 cells were co-treated with palmitate (500 µM) and OPI-T (25 or 50 µg/mL). Lipid accumulation was evaluated by Oil Red O and BODIPY staining, while oxidative stress was assessed by the DCF assay. Mitochondrial dynamics and autophagy were investigated through the analysis of key protein markers, including MFN2, DRP1, SQSTM1/p62 and LC3 II/I. OPI-T significantly attenuated palmitate-induced lipid accumulation (−18%) and reduced intracellular ROS production (−75%), while modulating mitochondrial dynamics toward a reduced fission phenotype with a marked increase in the MFN2/DRP1 ratio (1.66) and improving autophagy flux. In contrast, the Ramata di Montoro variety showed weaker or inconsistent effects under the same experimental conditions. Overall, these findings support the functional validation of a standardized onion peel-derived ingredient, highlighting its potential application as a bioactive component for functional food or nutraceutical development targeting hepatic steatosis and oxidative stress. Full article

Background/Objectives: Onion (Allium cepa) peems are an underutilized by-product rich in polyphenols. This study evaluated the physicochemical profile, and bioactive potential (antidiabetic, antimicrobial, antioxidant, and anticoagulant) of Moroccan red onion peels using integrated in vivo, in vitro, and in silico approaches. Methods: Moisture, pH, ash content, and mineral elements were determined, followed by phytochemical screening and three extractions: decoction E0, aqueous Soxhlet E1, and hydroethanolic Soxhlet E2 (70/30; ethanol/water, v/v). The measurement of polyphenols, flavonoids, and tannins was carried out using colorimetric methods, while the molecular profile was studied by high-performance liquid chromatography coupled to ultraviolet detection and electrospray ionization mass spectrometry (HPLC/UV-ESI-MS). Biological activities were determined using 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and total antioxidant capacity assays (in vitro antioxidant); microdilution (antimicrobial); prothrombin time and activated partial thromboplastin time (anticoagulant); and α-amylase/α-glucosidase enzymatic inhibition and oral glucose tolerance tests on normoglycemic rats. Also, acute toxicity was evaluated, and molecular interactions between these proteins and ligands (docking, molecular dynamics, and MM-PBSA) were analyzed. Results: Physicochemical analyses showed an acidic pH (3.06) and high ash content (15.21%), with the concentration of regulated elements remaining within FAO/WHO limits. The extractive content was between 6.90% E0 and 19.18% E2. The E1 extract had the maximum amount of total polyphenols (178.95 mg GAE/g); on the other hand, E2 was the richest in flavonoids by 121.43 mg QE/g. The HPLC/ESI-MS analysis of E0 revealed 20 compounds, among which flavonoids (84.93%) were predominant, with isorhamnetin (30.26%), followed by quercetin and its glycosylated forms. E1 showed the most potent antioxidant effects (IC₅₀ DPPH, 22.38 µg/mL, as that of ascorbic acid). The antibacterial activity of E0 was especially potent towards Enterobacter cloacae and Pseudomonas aeruginosa (MIC 75 µg/mL). A mild dose-dependent anticoagulant effect was seen. Antidiabetic activity was found to be outstanding: α-amylase (IC₅₀ 62.75 µg/mL) and α-glucosidase (IC₅₀ 8.49 µg/mL, stronger than acarbose) inhibitions were corroborated in vivo by a considerable decrease in the glycemic area under the curve. The molecular docking study in silico demonstrated strong molecular interactions, especially for quercetin 4′-O-glucoside with good binding energies. Conclusions: A. cepa peels from Morocco can be considered a safe plant matrix containing bioactive flavonoids with strong antioxidant and selective antimicrobial activities and promising antidiabetic effects, supported by molecular modeling. Full article

As a strategy to valorise onion peel (OP), a phenolic-rich extract was obtained and microencapsulated using the double emulsion technique for improved stability. Both free and microencapsulated OP extracts were added to fresh cheese to enhance its nutritional composition. The extract exhibited a high total phenolic content (TPC) and strong antioxidant capacity towards ABTS and DPPH radicals, with IC₅₀ of 9.5 and 36.1 mg_Extract∙L⁻¹, respectively. The extract demonstrated inhibitory capacities of 71% against α-amylase and 82% towards β-glucosidase. Quercetin was identified as the main phenolic compound, while potassium was the predominant mineral. The microencapsulation yielded an encapsulation efficiency of 91%, with an average particle size of 17.9 µm. Incorporating free and microencapsulated OP extract into the fresh cheese reduced syneresis, a favourable outcome, while preserving moisture levels, protein and ash content, and the pH. The incorporation of the free and microencapsulated OP extract enhanced the TPC and DPPH scavenging capacity of the cheeses. Results demonstrated the potential of using OP extract to enhance the antioxidant properties of fresh cheese, and to reduce syneresis, while promoting sustainability. These outcomes are particularly relevant from an industrial point of view, since an increase in antioxidant content might contribute to extending the product shelf-life. Full article

pH-responsive indicator films for intelligent food packaging applications are based on the embedding of a natural or synthetic dye in a polymeric substrate, preferably biobased and biodegradable. Although natural colorants like anthocyanins were extensively investigated in this respect, nature-inspired synthetic flavylium compounds could represent an alternative based on their higher stability. In this work, five novel synthetic 4′-aminoflavylium derivatives with different substitution patterns in the benzopyrylium core (compounds 1–5) were synthesized and characterized. Polyvinyl alcohol (PVA), as well as chitosan–PVA and chitosan–starch blends, were used to prepare pH-responsive indicator films having inserted each of the synthesized flavylium dyes or a natural onion peel extract. The PVA films with compounds 1 and 3, and the PVA–chitosan film with compound 1, exhibited antioxidant activity, highlighting their potential for active packaging applications. All indicator films showed pH responsiveness in the range of 2 to 12 and were subsequently tested in contact with the packaging atmosphere or in direct contact with pork and fish meat, at different temperatures (4 °C, 20 °C, and 40 °C) for 24 h to assess their colorimetric response to progressive spoilage. Although the differences were small, the films with the 7-hydroxy-4′-aminoflavylium derivative exhibited the earliest and most intense color change during storage of meat, starting from direct contact at 4 °C for 24 h, being able to identify the initial stages of meat spoilage, while the performance of the dihydroxy-substituted derivative was attenuated by incorporation in polymer matrices. This behavior was comparable to that of onion peel extract, but the synthetic flavylium derivative was more stable. The results can provide new opportunities for intelligent food packaging applications using biopolymer indicator films with 4′-aminoflavylium derivatives. Full article

Green-synthesis routes for producing CuO nanoparticles offer a simplified, sustainable, and low-cost replacement for conventional chemical methods, eliminating the need for harsh chemicals and providing an easily scalable process for industrial-level production. Although numerous studies have investigated synthesizing CuO nanoparticles from single plant extracts, comparative assessments of multi-plant-mediated CuO nanoparticles alongside synthetic CuO remain limited. In this work, CuO nanoparticles were green-synthesized from three different plant sources, namely ginger, red onion peels, and garlic, and their physicochemical and biological properties were tested against the synthetic CuO. All plant extracts produced pure-phased monoclinic CuO nanoparticles as confirmed by UV–Vis, XRD, FTIR, and SEM/EDX analyses. SEM showed distinct nanoparticle morphologies, with CuO from ginger extract exhibiting uniform nanocubes, while nanoparticles from red onion and garlic extracts exhibited more aggregated and irregular structures. Their crystallite sizes were 8–9 nm lower than the ~11 nm observed for the synthetic CuO, highlighting the phytochemical role in shaping the nanoparticles’ morphology. The antibacterial efficacy against S. aureus and E. coli showed that ginger-derived and synthetic CuO had the strongest bacterial inhibition and bactericidal potency compared to onion- and garlic-derived CuO samples. However, synthetic CuO had the highest cytotoxicity risk, hindering its suitability for biological uses, while CuO-ginger maintained good cell viability at moderate concentrations. CuO-onion and CuO-garlic gave lower antibacterial cytocompatibility performance due to their thicker capping layers, which led to decreased Cu²⁺ release and ROS production. Ginger-derived CuO achieved an optimal trade-off between antibacterial and cytotoxic efficiency, highlighting its prospects as a candidate for biomedical applications. Full article

This study developed biodegradable carboxymethyl cellulose (CMC) films crosslinked with citric acid (CA) and X-ray irradiation as sustainable packaging alternatives to reduce plastic use. CMC/CA films were subjected to three doses of X-ray irradiation at two energy levels. CMC/CA films exposed to 10 kGy at 350 kV exhibited a significant three-fold reduction in water solubility compared to non-irradiated films, while also lowering water vapor and oxygen permeability without affecting mechanical strength (p ≤ 0.05). FTIR analysis confirmed the esterification between CMC and CA, which reduced the film hydrophilicity. Onion peel extract (OPE) was added as a bioactive compound to provide antifungal properties. Release studies showed reduced OPE diffusion in irradiated films, with lower release rate constant (k_kp) values. The in situ test on cheese inoculated with Penicillium commune showed that the irradiated bioactive films prolonged shelf life, reducing fungal counts to log 2.3 CFU/g after 18 days compared to log 5.7 CFU/g in control samples. Cheese wrapped with irradiated bioactive films had weight loss from 1.05 to 9.37%, whereas uncovered samples exhibited the highest weight loss (2.07 to 15.07%). Overall, irradiation-assisted crosslinking and OPE incorporation improved film functionality, offering a sustainable and effective packaging solution for cheese preservation within a circular economy framework. Full article

This study focuses on the optimization of modern extraction techniques for selected by-product materials, including apple, lemon, and tangerine peels, and onion skins, using artificial neural network (ANN) models. The extraction methods included ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) with water as the extractant, as well as maceration (MAC) with natural deep eutectic solvents (NADES). Key parameters, such as total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities, including reducing power (EC₅₀) and free radical scavenging capacity (IC₅₀), were evaluated to compare the efficiency of each method. Among the techniques, UAE outperformed both MAE and MAC in extracting bioactive compounds, especially from onion skins and tangerine peels, as reflected in the highest TPC, TFC, and antioxidant activity. UAE of onion skins showed the best performance, yielding the highest TPC (5.735 ± 0.558 mg CAE/g) and TFC (1.973 ± 0.112 mg RE/g), along with the strongest antioxidant activity (EC₅₀ = 0.549 ± 0.076 mg/mL; IC₅₀ = 0.108 ± 0.049 mg/mL). Tangerine peel extracts obtained by UAE also exhibited high phenolic content (TPC up to 5.399 ± 0.325 mg CAE/g) and strong radical scavenging activity (IC₅₀ 0.118 ± 0.099 mg/mL). ANN models using multilayer perceptron architectures with high coefficients of determination (r² > 0.96) were developed to predict and optimize the extraction results. Sensitivity and error analyses confirmed the robustness of the models and emphasized the influence of the extraction technique and by-product type on the antioxidant parameters. Principal component and cluster analyses showed clear grouping patterns by extraction method, with UAE and MAE showing similar performance profiles. Overall, these results underline the potential of UAE- and ANN-based modeling for the optimal utilization of agricultural by-products. Full article

Onion (Allium cepa L.) peels represent a major agro-industrial by-product and are a rich source of polyphenols, with recognized antioxidant properties. This study compared the polyphenolic profile of two onion cultivars peels: red “Rossa di Tropea” and yellow “Recas”. Their digestive stability, intestinal bioavailability, and antioxidant activity were evaluated. Hydroalcoholic extracts were characterized by HPLC-DAD, subjected to a static gastrointestinal digestion model, and assessed for transport across differentiated Caco-2 monolayers. Antioxidant properties were determined using DPPH, FRAP, Cellular Antioxidant Activity (CAA), and intracellular glutathione (GSH) assays. Red peels contained a higher total polyphenol content (28.44 mg/g DW) than yellow peels (15.61 mg/g DW), including anthocyanins uniquely present in the red cultivar. Digestive stability varied markedly between cultivars, with yellow peels showing greater intestinal recovery (72.7%) than red peels (49.1%). Glycosylated flavonols were more stable and exhibited moderate intestinal transport (Papp = 1.1–9.9 × 10⁻⁶ cm·s⁻¹), whereas quercetin aglycone showed low permeability. Red peel extracts demonstrated stronger chemical antioxidant activity, while yellow peels were more effective in cell-based assays, displaying higher CAA values and inducing a pronounced increase in intracellular GSH. Overall, onion peel extracts exhibit promising antioxidant and biological properties. However, their limited bioavailability highlights the need for formulation strategies to enhance gastrointestinal stability and intestinal uptake, supporting their potential use as sustainable functional ingredients. Full article

As by-products rich in flavonoids and phenolic compounds, onion peels are globally undervalued and often discarded. This study reports the synthesis of carbon quantum dots (CQDs) from onion peels and evaluates their antimicrobial effectiveness against key foodborne pathogens and biofilms on common food contact surfaces, including plastic, stainless steel, and rubber. The CQDs exhibited a quasi-spherical shape with particle sizes ranging from 1.7 to 9.0 nm and contained abundant oxygen- and nitrogen-functional groups, as confirmed by FT-IR and XPS analyses. The CQDs showed significant antimicrobial activity, with minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against Salmonella typhimurium, Escherichia coli O157: H7, Listeria monocytogenes, and Staphylococcus aureus of 2200/2800 µg/mL, 1400/2000 µg/mL, 1200/1800 µg/mL, and 400/600 µg/mL, respectively. Time-kill assays confirmed these results. In biofilm tests, S. typhimurium formed biofilms more easily than L. monocytogenes. Washing with CQD solution for 5 min reduced biofilm presence by 81.6–91.5% for S. typhimurium and over 74% for L. monocytogenes, with more than 94% reduction after 10 min of treatment (over 94% for S. typhimurium; 95.8–98.8% for L. monocytogenes) across all surfaces, especially on plastic and stainless steel. These findings indicate that onion peel-derived CQDs are promising, eco-friendly agents for disrupting biofilms and turning undervalued waste into valuable products. Full article

Agro-industrial by-products are rich in polyphenols with potential applications as natural antimicrobials in food systems. This study evaluated the total polyphenol content (TPC) and antimicrobial activity of orange (Citrus sinensis), onion (Allium cepa), cacao (Theobroma cacao), and tamarillo (Solanum betaceum) peel extracts against Listeria monocytogenes, individually and in combination with Saccharomyces cerevisiae. TPC was quantified using the Folin–Ciocalteu method, and minimum inhibitory concentrations (MICs) were determined using broth microdilution. Statistical analysis (two-way ANOVA, p < 0.05) assessed the effect of extract type and yeast addition on MIC values. The highest TPC was recorded in Theobroma cacao peel extract (85.3 ± 2.1 mg GAE/g DW). All extracts inhibited L. monocytogenes, with MICs ranging from 2.5 to 10 mg/mL. This was reduced to 1.25–5 mg/mL when combined with S. cerevisiae, indicating synergism (F = 11.42, p = 0.003). These results suggest that polyphenol-rich peel extracts enhanced by S. cerevisiae can be incorporated into beverage preservation systems, aligning with clean-label trends. This study integrates quantitative and mechanistic analyses to link extraction methods, polyphenol content, and synergistic inhibition with Saccharomyces cerevisiae, providing a coherent analytical framework for sustainable antimicrobial strategies. Full article

Microplastics, plastic particles smaller than 5 mm, are now ubiquitous and represent a form of pollution that threatens ecosystems and human health, infiltrating the environment, air, and food chain. The search for solutions to microplastics requires industrial policies that limit plastic production and technological innovations for removal and recycling. Specifically, this paper reports a sustainable and cost-effective method for the detection of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) microplastics using nitrogen-doped carbon dots (N-CD) synthesized from onion peel and L-cysteine via hydrothermal carbonization. Two precursor ratios (1:1 and 1:0.30 w/w) were evaluated. The resulting N-CDs exhibited bright yellow-green fluorescence (470–500 nm) and excitation-dependent photoluminescence under 365 nm UV light. FTIR and UV-Vis spectroscopy confirmed the presence of nitrogen-containing functional groups and effective graphitization, particularly in the 1:0.30 ratio. Fluorescence imaging revealed stronger intensity and greater stain uniformity in thermally softened MPs treated with 1:0.30 N-CDs, with a peak emission of 10,230.02 a.u. at 2 h and PMT 11—surpassing the 1:1 ratio. Bandgap and absorbance analyses supported the superior optical behavior of the lower-concentration formulation. Image analysis further indicated increased luminescent area over time, and two-way ANOVA confirmed statistically significant effects of heating time and PMT settings (p < 0.05). Compared to traditional filtration staining, thermal-assisted application offered enhanced and stable fluorescence. These findings demonstrate the efficacy of green-synthesized N-CDs for MP detection, with potential scalability and environmental applicability. Future work should explore alternative biomass sources and assess N-CD performance under field conditions to optimize environmental sensing strategies. Full article