Search Results (79)

Polysaccharide-based nanocarriers offer a novel delivery system for improving the stability, controlled release, and biological functionality of plant-derived bioactive materials. Olive leaf extract (OLE), rich in polyphenolic compounds with antioxidant and other bioactive properties, is limited by low stability and bioavailability. In this study, OLE-loaded alginate–chitosan nanoparticles were prepared using ionotropic gelation–polyelectrolyte complexation (IG-PEC) method, and their physicochemical properties, cytotoxic behavior, and potential prebiotic effects were evaluated. The resulting nanoparticles (232–237 nm) exhibited uniform spherical morphology, negative zeta potentials, and improved colloidal stability. Free OLE demonstrated concentration-dependent and selective cytotoxicity toward A549 and MCF-7 cancer cells, while exhibiting lower toxicity toward normal fibroblasts. In contrast, unloaded and OLE-loaded nanoparticles (1X, 2X) showed low cytotoxicity, suggesting superior biocompatibility of the polysaccharide nanocarrier. Notably, cultures supplemented with OLE-loaded nanoparticles showed a trend toward higher probiotic growth compared to free OLE, indicating a potential prebiotic effect and improved microbial tolerance to polyphenols during extended exposure. These findings highlight the advantages of polysaccharide-based nanoencapsulation for both stabilizing bioactive materials and supporting favorable microbial responses. The developed OLE nanocarriers may serve as a promising platform for nutraceutical, biomedical, and functional food applications. Full article

Fermented foods and prebiotics are increasingly studied for their potential therapeutic roles in metabolic disorders. In this study, 52 male Wistar rats maintained on a high-fat, high-sucrose (HFS) diet were supplemented for 8 weeks with either water kefir (providing approximately 10⁵ CFU per rat per day), olive leaf polyphenols (equivalent to 1.6 mg oleuropein daily), or a combination of both. Both interventions ameliorated HFS-diet induced weight gain, accompanied by reductions in subcutaneous and mesenteric fat, without additive effects when combined. Moreover, olive polyphenols decreased liver weight, suggesting a potential protective effect against hepatic steatosis through Fasn modulation. These metabolic improvements were accompanied by enhanced gut microbiota diversity. Together, these findings highlight water kefir and olive leaf polyphenols as potential dietary strategies for the management of obesity, hepatic steatosis, and dyslipidemia. Full article

Background/Objectives: Several studies reported that olive leaf extract (OLE) may exert potent anti-cancer activities against human solid and hematological tumors. Such effects are mostly related to the polyphenol oleuropein and its derivatives, which are highly concentrated in OLE. Here, we investigated the anti-tumor effects of OLE in vitro against human acute leukemia and lymphoma cells. Methods: Cell proliferation and apoptosis have been evaluated by flow cytometry (using CFSE and Annexin-V/7AAD, respectively) in the presence or absence of OLE at different concentrations and in combination with or without chemotherapeutic drugs. Cellular pathways have been analyzed using antibody arrays. Results: OLE inhibited cell proliferation and induced apoptosis in B-acute lymphoblastic leukemia (B-ALL) and, to a lesser extent, in lymphomas and acute myeloid leukemia (AML) cell lines. Notably, OLE-induced apoptosis also occurs in primary leukemic blasts from B-ALL patients, both at diagnosis and at relapse, but only marginally in primary AML blasts. The expression and phosphorylation of proteins involved in the induction of apoptosis were modulated by OLE in B-ALL, whereas modest effects were observed in AML. Interestingly, some proteins were modulated in opposite ways in B-ALL and AML, potentially explaining their different responses to OLE. Finally, a synergistic and additive effect was observed for OLE in combination with cytarabine, but not with cyclophosphamide. Conclusions: We may envisage that OLE may be used as a food supplement in B-ALL patients treated with cytarabine, taking advantage of the potentiated effect of chemotherapy, without additional side effects. Full article

Olive leaves are a valuable source of natural bioactive compounds, particularly polyphenols and flavonoids, recognized for their potent antioxidant and health-promoting properties. The extraction of these high-value products has gained increasing attention due to their relevance in food sustainability and the circular economy. However, the concentrations and profiles of these compounds vary substantially depending on the olive variety and the extraction method applied. This study evaluated the influence of extraction method and olive variety on the phenolic composition and antioxidant potential of olive leaf extracts from nine cultivars cultivated in Morocco. Two conventional extraction techniques, maceration and Soxhlet extraction, were compared for their efficiency in recovering extraction yield, total phenolic content, total flavonoid content, and total condensed tannins, along with antioxidant activity measured by DPPH and ABTS radical scavenging assays. Analyses of variance indicated that varietal differences were the predominant source of variation in phenolic composition and antioxidant capacity, whereas the extraction method mainly influenced yield. Soxhlet extraction enhanced phenolic recovery and antioxidant potential, while maceration favored flavonoid extraction. These findings highlight the potential of olive leaf extracts derived from Manzanilla, Haouzia, Picual, and Moroccan Picholine varieties using Soxhlet as sustainable natural antioxidants for functional, cosmetic, and pharmaceutical uses. Full article

The olive tree (Olea europaea L.) is a keystone species in Mediterranean agroecosystems, where it plays a central economic and cultural role. However, the Mediterranean Basin is increasingly exposed to climate change, with rising temperatures and prolonged droughts threatening the long-term sustainability of olive cultivation. Understanding the adaptive responses of olive trees to water scarcity is critical for ensuring resilience in olive-based agroecosystems. This study investigates the functional responses of the Moroccan Menara olive cultivar under different controlled deficit irrigation (DI) strategies, namely regulated (RDI) and sustained (SDI) deficit irrigation. By analyzing key leaf functional and biochemical traits, we assessed how varying levels of water stress influence resource allocation and stress mitigation mechanisms. Under full irrigation (100% of crop water evapotranspiration) throughout the growing season and during sensitive growth periods, trees exhibited increased stomatal density, leaf area, and higher leaf carbon, nitrogen, and phosphorus contents, traits associated with enhanced growth and photosynthetic capacity. Meanwhile, under RDI treatments, with a 20% water reduction during sensitive periods and 40% during non-sensitive periods, Menara trees showed increased leaf tissue density and accumulation of polyphenols. SDI treatments, however, triggered higher concentrations of osmoprotectants (glycine, sugars, and proline), reduced stomatal density, and smaller leaf area associated with increased stomatal size. Principal component analysis revealed a major trade-off between growth-related and stress-protective traits, primarily driven by water availability during phenological growth stages. Notably, the strength of this trade-off was positively associated with olive fruit yield, underscoring the importance of strategically timed irrigation in balancing physiological resilience and productivity. These findings emphasize the crucial role of irrigation strategy in modulating functional responses of olive trees to water deficit, offering insights into optimizing water use under future climate scenarios. Full article

Background/Objectives: Olive leaf (Olea europaea L.), a by-product of olive oil production, is rich in bioactive phenolics but limited in application due to poor solubility and stability. To improve their bioavailability, this study presents a comparative encapsulation strategy using three phospholipid-based liposomal systems (AL, PG90, and PH90) loaded with ethanolic olive leaf extract. Methods: Liposomes were characterized by physicochemical parameters, encapsulation efficiency (EE), antioxidant activity, morphology, release kinetics under simulated physiological conditions, and 60-day stability. To the best of our knowledge, this is the first direct comparison of AL, PG90, and PH90 matrices for olive leaf extract encapsulation. Results: HPLC and GC-MS confirmed successful encapsulation, with oleuropein showing the highest EE (up to 76.18%). PH90 favored retention of non-polar triterpenes, while AL and PG90 preferentially encapsulated polar flavonoid glycosides. FT-IR analysis verified extract integration into phospholipid bilayers. Antioxidant activity remained high in all loaded formulations, with negligible activity in empty liposomes. Extract-loaded systems exhibited reduced particle size, higher viscosity, and more negative electrophoretic mobility, enhancing colloidal stability. PG90 liposomes displayed the most stable mobility profile over 60 days. Transmission electron microscopy and nanoparticle tracking analysis revealed formulation-dependent vesicle morphology and concentration profiles. Release studies demonstrated significantly prolonged polyphenol diffusion from PG90 liposomes compared to the free extract. Conclusions: Phospholipid composition critically governs encapsulation selectivity, stability, and release behavior. Tailored liposomal systems offer a promising strategy to enhance the stability and delivery of olive leaf polyphenols, supporting their application in bioactive delivery platforms. Full article

In this study, an innovative and sustainable strategy for the valorization of olive leaves, an underutilized agro-industrial byproduct, was developed through enzymatic-assisted aqueous extraction to produce a polyphenol-rich olive leaf extract (OLE). The extract contained notable concentrations of hydroxytyrosol (0.53 mg/L), luteolin-7-o-glucoside (0.70 mg/L), apigenin-4-o-glucoside (0.18 mg/L), and oleuropein (4.24 mg/L). For the first time, this OLE was successfully nanoencapsulated into layered double hydroxides (LDHs) synthesized at Zn²⁺/Al³⁺ molar ratios of 1:1, 2:1, and 3:1, resulting in a series of OLE@LDH_Zn/Al_x/1 nanohybrids. Comprehensive structural characterization confirmed the successful intercalation of OLE within the LDH interlayer galleries. Antioxidant activity (via DPPH assay), total polyphenol content (TPC), and antibacterial tests were conducted to evaluate functionality. Among the nanohybrids, OLE@LDH_Zn/Al_1/1 exhibited the highest TPC (606.6 ± 7.0 mg GAE/L), the lowest EC_50,DPPH, EC_50,ABTS, and EC_50,FRAP values (27.88 ± 1.82, 25.70 ± 0.76, and 39.42 ± 2.16 mg/mL), and superior antibacterial performance against E. coli and S. aureus. Moreover, pH-dependent release revealed targeted polyphenol release under acidic conditions (pH = 1), simulating gastric environments. These results highlight LDHs, particularly with a Zn/Al ratio of 1:1, as promising nanocarriers for the stabilization and controlled release of plant-derived polar phenols, with potential applications in nutrition, food preservation, and biomedicine. Full article

Knowledge about the composition (volatile and non-volatile) and functionality of natural extracts from Mediterranean plants serves as a basis for their further application. In this study, five selected plants were used for the extraction of plant metabolites. Leaves and flowers of Critmum maritimum, Rosmarinus officinalis, Olea europea, Phylliera latifolia and Mellisa officinalis were collected, and a total of 12 extracts were prepared. Extractions were performed under microwave-assisted conditions, with two solvent types: water (W) and a hydroalcoholic (ethanolic) solution (HA). Detailed extract analysis was conducted. Phenolics were analyzed by detecting individual bioactive compounds using high-performance liquid chromatography and by calculating total phenolic and total flavonoid content through spectrophotometric analysis. Higher concentrations of total phenolics and total flavonoids were obtained in the hydroalcoholic extracts, with the significantly highest total phenolic and flavonoid values in the rosemary hydroalcoholic extract (3321.21 mg_GAE/L) and sea fennel flower extract (1794.63 mg_QE/L), respectively; and the lowest phenolics in the water extract of olive leaves (204.55 mg_GAE/L) and flavonoids in the water extracts of sea fennel leaves, rosemary, olive and mock privet (around 100 mg_QE/L). Volatile organic compounds (VOC) were detected using HS-SPME/GC–MS (Headspace Solid-Phase Microextraction coupled with Gas Chromatography-Mass Spectrometry), and antioxidant capacity was estimated using DPPH (2,2-diphenyl-1-picrylhydrazyl assay) and FRAP (Ferric Reducing Antioxidant Power) methods. HS-SPME/GC–MS analysis of samples revealed that sea fennel had more versatile profile, with the presence of 66 and 36 VOCs in W and HA sea fennel leaf extracts, 52 and 25 in W and HA sea fennel flower extracts, 57 in rosemary W and 40 in HA, 20 in olive leaf W and 9 in HA, 27 in W mock privet and 11 in HA, and 35 in lemon balm W and 10 in HA extract. The lowest values of chlorophyll a were observed in sea fennel leaves (2.52 mg/L) and rosemary (2.21 mg/L), and chlorophyll b was lowest in sea fennel leaf and flower (2.47 and 2.25 mg/L, respectively), while the highest was determined in olive (6.62 mg/L). Highest values for antioxidant activity, determined via the FRAP method, were obtained in the HA plant extracts (up to 11,216 mg_AAE/L for lemon balm), excluding the sea fennel leaf (2758 mg_AAE/L) and rosemary (2616 mg_AAE/L). Considering the application of these plants for fresh fish preservation, antimicrobial activity of water extracts was assessed against Vibrio fischeri JCM 18803, Vibrio alginolyticus 3050, Aeromonas hydrophila JCM 1027, Moraxella lacunata JCM 20914 and Yersinia ruckeri JCM 15110. No activity was observed against Y. ruckeri and P. aeruginosa, while the sea fennel leaf showed inhibition against V. fisheri (inhibition zone of 24 mm); sea fennel flower was active against M. lacunata (inhibition zone of 14.5 mm) and A. hydrophila (inhibition zone of 20 mm); and rosemary and lemon balm showed inhibition only against V. fisheri (inhibition zone from 18 to 30 mm). This study supports the preparation of natural extracts from Mediterranean plants using green technology, resulting in extracts rich in polyphenolics with strong antioxidant potential, but with no clear significant antimicrobial efficiency at the tested concentrations. Full article

Postprandial dysmetabolism, which refers to the impaired regulation of glucose and lipid levels after meals, is recognized as an independent risk factor for cardiovascular diseases (CVDs). Diets rich in polyphenols have demonstrated potential in improving postprandial hyperglycemia and hyperlipidemia. This study investigates the effects of olive leaf polyphenols on postprandial metabolic outcomes following a high-fat and high-carbohydrate meal. A total of 36 healthy adults participated in a three-arm randomized crossover trial. They ingested either a biscuit made from olive leaf powder (OLB), olive leaf tea (OLT), or a placebo meal (CTRL) to assess the impact of olive leaf polyphenols on postprandial glycemia, lipid levels, platelet aggregation factor (PAF), and plasma antioxidant status (TAC). Although no statistically significant differences were observed in the primary biomarkers, including glucose and lipid profiles, a delayed insulin response was noted in the interventions involving olive leaf. These findings suggest that while acute olive leaf supplementation did not significantly alter postprandial glycemia or lipidemia, it may subtly influence insulin kinetics. Further research is needed to explore the long-term effects of olive leaf polyphenols on metabolic health, especially in populations at risk for CVDs. Full article

Domestic food waste and agro-industrial by-products (AIBPs) occurring throughout the food chain, including production, processing, and storage, have become a global sustainability concern. Interestingly, this waste and these by-products contain a significant amount of commercially vital bioactive compounds, including polyphenols and carotenoids. Remarkably, discarded by-products such as fruit and vegetable peels contain more bioactive compounds than edible pulp. Thus, valorizing this waste and these by-products for commercially vital bioactive products can solve their disposal problems and help alleviate climate change crises. Additionally, it can generate surplus revenue, significantly improving food production and processing economics. Interestingly, several bioactive extracts derived from citrus peel, carrot pomace, olive leaf, and grape seed are commercially available, highlighting the importance of agro-food waste and by-product valorization. Considering this background information, this review aims to provide holistic information on major AIBPs; recovery methods of bioactive compounds focusing on polyphenols, carotenoids, oligosaccharides, and pectin; microencapsulation of isolated bioactive for enhanced physical, chemical, and biological properties; and their commercial application. In addition, green extraction methods are discussed, which have several advantages over conventional extraction. The concept of the circular bio-economy approach, challenges in waste valorization, and future perspective are also discussed. Full article

Background: Consumer demand for plant-based milk alternatives, particularly oat-based milk, has increased due to perceived health benefits and environmental sustainability. However, challenges remain in improving their nutritional profile and physical stability while promoting the use of local agricultural resources and reducing food waste. Methods: This study developed and evaluated fortified oat-based milk formulations using locally sourced oats cultivated in central Italy. Two valorization strategies were tested: (i) the addition of raspberry powder derived from juice processing byproducts and (ii) the substitution of water with infusions of raspberry and olive leaves. The nutritional composition, antioxidant activity, physical stability, and sensory properties were assessed. Results: Replacing water with leaf infusions significantly increased total polyphenol content (up to 688 mg GAE/100 g DW) and antioxidant activity but compromised physical stability, resulting in higher separation indexes during refrigerated storage. Conversely, adding raspberry powder moderately enhanced antioxidant properties while maintaining emulsion stability. Sensory evaluation showed that enriched formulations reduced undesirable attributes (e.g., floury and cereal notes), although higher concentrations of leaf infusions increased astringency and bitterness. Conclusions: The fortification of oat-based milk with locally sourced raspberry powders and leaf infusions effectively enhances its nutritional and antioxidant properties while influencing its physical and sensory characteristics. This strategy supports the valorization of local agricultural byproducts and promotes the development of sustainable, functional plant-based beverages. Full article

Polyphenol-rich extracts derived from agricultural by-products exhibit promising antiviral properties. This study evaluated the antiviral potential of extracts from red onion peels, vineyard prunings, olive prunings and chicory leaves against human coronavirus HuCoV-229E. Subcritical water extraction and resin adsorption techniques were applied to produce the extracts. The extracts were further characterised for their bioactive content, and three out of four extracts showed a high polyphenol content (>200 mg/g). The antiviral activity was assessed through viral infectivity and replication inhibition assays in human MRC-5 host cells. The results indicate that chicory leaf and red onion peel extracts demonstrated significant antiviral effects, with effective concentrations (EC₅₀) of 61.43 µg/mL and 10.1 µg/mL, respectively. Olive pruning extract exhibited moderate activity, while vineyard pruning extract showed limited efficacy. These findings suggest that polyphenol-rich agricultural by-products could serve as sustainable sources for antiviral agents, warranting further investigation into their mechanisms of action and potential applications against other coronaviruses, including SARS-CoV-2. Full article

Phenolic antioxidant intake is encouraged to prevent oxidative damage, and antioxidant synergy is considered an advantage in adding polyphenols from varied plants. This study investigated the antioxidant and synergistic interactions among olive leaf (OL), bay laurel (BL), and rosemary (RL) leaf powder mixture (LPM: OL + BL + RL), using in vitro chemical tests [TPC, ORAC, TEAC-ABTS, FRAP; combination index (CI)], and in vivo validation on blood oxidative status, metabolic profile, and intestinal histomorphology in laying hens. The in vitro study indicated a whole higher antioxidant capacity for the LPM than respective single/double-leave combinations. The LPM CI value (IC50, 0.60) indicated a synergistic effect compared to the binary combinations. Thus, the LPM was validated in vivo through dietary supplementation on sixty Lohmann Brown hens (30 weeks old), reared in an indoor–outdoor rearing system divided. The hens were allocated into two experimental groups (n. 30): basal control diet group; and diet supplemented group with 6 g/kg feed of LPM) containing OL, BL, and RL (respectively, at 65.7%:18.9%:15.4%), for 60 days. The LPM improved (p < 0.05) the oxidative status (TAS, FRAP; ROMs, TBARs) and vitamin E level, metabolic and immunological profiles, and it induced region-specific changes in the morphology and carbohydrate composition of mucins along intestinal tracts of the animals. These findings could provide a valuable strategy for identifying synergistic combinations in functional feed formulations for laying hens. Full article

Sustainable agro-waste revaluation is critical to enhance the profitability and environmental footprint of the olive oil industry. Herein, the valorization of olive leaf pruning waste from five cultivars (‘Caiazzana’, ‘Carolea’, ‘Itrana’, ‘Leccino’, and ‘Frantoio’) employed green extraction methods to recover compounds with potential health benefits. Sequential ultrasound-assisted maceration (UAM) in n-hexane and ethanol was compared with a compressed fluid extraction strategy consisting of supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) for their efficiency in recovering distinct classes of bioactives. Chemical profiling by UHPLC-HR-MS/MS (ultra-high-performance liquid chromatography high-resolution tandem mass spectrometry) and GC-MS (gas chromatography mass spectrometry) showed that UAM-EtOH effectively extracted polyphenols (especially luteolin derivatives) and triterpenes (notably maslinic acid), while PLE yielded the highest amount of secoiridoids (e.g., secologanoside). PLE extracts showed better antiradical activities, putatively due to a higher content of flavonoids, secoiridoids, and HCA derivatives than UAM-EtOH ones, as these latter also contained 20–40% (cultivar-dependent) of triterpenes. SFE extracts with a higher concentration of fatty acids and triterpenes showed moderate antioxidant activities but very high AChE inhibition. This study highlights the importance of selecting appropriate extraction methodologies based on the target bioactive compounds and underscores the potential of olive leaf extracts for sustainable bio-products. Full article

Background: Olive leaves are a rich source of polyphenols, predominantly secoiridoids, flavonoids, and simple phenols, which exhibit various biological properties. Extracts prepared from olive leaves are associated with hypoglycemic, hypotensive, diuretic, and antiseptic properties. Upon ingestion, a substantial fraction of these polyphenols reaches the colon where they undergo extensive metabolism by the gut microbiota. Host characteristics, like age, can influence the composition of the gut microbiome, potentially affecting the biotransformation of these compounds. Therefore, it can be hypothesised that differences in the gut microbiome between young and elderly individuals may impact the biotransformation rate and the type and amount of metabolites formed. Methods: An in vitro biotransformation model was used to mimic the conditions in the stomach, small intestine and colon of two age groups of healthy participants (20–30 years old, ≥65 years old), using oleuropein as a single compound and an olive leaf extract as test compounds. The bacterial composition and metabolite content were investigated. Results: The study revealed that, while the same metabolites were formed in both age groups, in the young age group, less metabolite formation was observed, likely due to a reduced viable cell count. Most biotransformation reactions took place within the first 24 h of colon incubation, and mainly, deglycosylation, hydrolysis, flavonoid ring cleavage, and demethylation reactions were observed. A bacterial composition analysis showed a steep drop in α-diversity after 24 h of colon incubation, likely due to favourable experimental conditions for certain bacterial species. Conclusions: Both age groups produced the same metabolites, suggesting that the potential for polyphenols to exert their health-promoting benefits persists in healthy older individuals. Full article