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.

In this study, an innovative and sustainable strategy for the valorization of olive leaves—an underutilized agro-industrial by-product—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 EC50,DPPH, EC50,ABTS, and EC50,FRAP values (27.881.82, 25.700.76, and 39.422.16mg/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 polyphenols, with potential applications in nutrition, food preservation, and biomedicine.

This study investigates the impact of olive tree variety and environmental stress on the production of bioactive compounds in olive leaves, focusing on phenolic content and antioxidant capacity. Three olive varieties—Kalamata, Koroneiki, and wild olive (Olea europaea var. Silvestris)—from two climatically distinct regions in Greece (Stamna and mountainous Paravola) were analyzed. Using three sustainable extraction methods, Ultrasound-Assisted Extraction (UAE), Enzyme-Assisted Extraction (EAE), and Microwave-Assisted Extraction (MAE), the total polyphenolic content (TPC) and antioxidant activity (AA%) of the olive leaf extracts were quantified. Results revealed significant variation in polyphenolic yield depending on both extraction technique and environmental conditions. EAE consistently outperformed other methods in polyphenol recovery, especially from wild olive leaves in the higher-stress environment of Paravola, which showed the highest TPC. This work underscores the synergistic role of varietal and climatic factors in secondary metabolite accumulation and highlights the potential of green extraction technologies in valorizing olive by-products.

Olive leaves are an abundant agro-industrial by-product rich in oleuropein, yet they remain largely underutilized. The objective of this study is to a) develop a green microwave-assisted extraction (MAE) method for an oleuropein-rich extract, b) encapsulate it into edible natural zeolite to form OLE@NZ nanohybrids, and, c) evaluate their application in fortified salt and active gelatin films. MAE using only water at 96 °C for 5 min yielded a dry extract with 25.4% (w/w) oleuropein and a total phenolic content of 781 mg GAE/100 mL. The extract was successfully adsorbed onto clinoptilolite-type zeolite and the resulting nanohybrids showed strong antioxidant activity (EC_50,DPPH = 2.74 mg, TPC = 426 mg GAE/g). A fortified salt containing 5% w/w OLE@NZ fully preserved the nanohybrid’s antioxidant activity. Extruded gelatin films incorporating 5–15% OLE@NZ exhibited a concentration-dependent increase in antioxidant activity (up to 14-fold higher than the blank film), together with a 5- to 7-fold enhancement, while maintaining good mechanical properties. The total phenolic content of the films correlated linearly with nanohybrid loading, with phenolic recovery of 68% both at 5 and 10% loading and 58% at 15%). Overall, these findings demonstrate that MAE is a rapid, and environ-mentally friendly approach for obtaining oleuropein-rich olive leaf extract (OLE), while OLE@NZ nanohybrids provide effective antioxidant additives for functional salt formulations and active gelatin films, supporting a circular bioeconomy strategy.

Mulberry fruits are rich sources of bioactive phytochemicals with potential cardiovascular-relative bioactivity properties. In the present study, phenolic/alkaloid-enriched extracts from black (Morus nigra) and white (Morus alba) mulberries were chemically characterized and evaluated for their anti-atherogenic and antiplatelet activities in vitro. LC-HRMS analysis revealed distinct phytochemical profiles, with the black mulberry extract (BlackM) being characterized by a high abundance of anthocyanins, predominantly cyanidin- and pelargonidin-based glycosides, whereas the white mulberry extract (WhiteM) was particularly rich in pyrrolidine alkaloids, including morusimic acid isomers. Both extracts also contain flavonoids and phenolic acids, such as rutin, quercetin derivatives, and chlorogenic acid derivatives. BlackM markedly increased the resistance of low-density lipoprotein (LDL) to Cu²⁺-induced oxidation, whereas WhiteM more effectively inhibited the propagation phase of lipid peroxidation and significantly suppressed arachidonic acid-induced platelet aggregation. BlackM induced a modest, albeit non-significant, reduction in neutrophil extracellular trap (NET) formation. To the best of our knowledge, this is among the first studies to comparatively investigate the effects of black and white mulberry extracts on LDL oxidation, platelet aggregation and NETs formation. Overall, these findings support the potential use of mulberry-derived phytochemicals as functional food ingredients and nutraceuticals for the prevention of atherothrombotic cardiovascular disease.