The microencapsulation of bioactive extracts of Chilean papaya waste, including both seeds and skin, was investigated. Papaya waste extract microcapsules utilizing maltodextrin at 10% (MD10), 20% (MD20), and 30% (MD30) (w/v) as the wall material through the freeze-drying process were obtained, and subsequently their physicochemical, antioxidant, and antimicrobial properties were evaluated. The TPC efficiency and yield values achieved were more than 60% for the microencapsulated seed and skin extracts, respectively. The best results for phenolic and antioxidant compounds were found in the microencapsulated seed extract with MD20, with a value of 44.20 ± 3.32 EAG/g DW for total phenols and an antioxidant capacity of 12.0 ± 0.32 mol ET/g DW for the DPPH and 236.3 ± 4.1 mol ET/g DW for the FRAP assay. In addition, the seed and skin samples reduced ROS generation in H₂O₂-treated Hek293 cells. In terms of antimicrobial activity, values ranging from 7 to 15 mm of inhibitory halos were found, with the maximum value corresponding to the inhibition of S. aureus, for both microencapsulated extracts. Therefore, the successful microencapsulation of the waste bioactive extracts (seed and skin) with the demonstrated antimicrobial and antioxidant properties highlight the bioactivity from Chilean papaya waste resources.

The temperate rainforests of southern Chile host a rich diversity of plants traditionally used in medicine, yet their bioactive potential remains underexplored. This study evaluated the chemical composition, antioxidant capacity, antibacterial activity, and cell viability of ethanolic leaf extracts from Cissus striata (CS), Mitraria coccinea (MC), and Raukaua laetevirens (RL), compared with Buddleja globosa (BG), a well-known medicinal shrub. Extracts were obtained using 70% ethanol, ensuring high recovery of polyphenolic compounds while avoiding thermal degradation. The total phenolic content (TPC) was highest in CS, exceeding values reported for green tea, while MC exhibited the greatest total flavonoid content (TFC). HPLC–MS/MS analysis showed that RL was rich in rutin, while CS exhibited a higher quercetin content. Antioxidant activity assessed through ABTS, DPPH, and FRAP assays, was correlated with polyphenolic composition. CS showed the highest antioxidant potential, surpassing green tea by ~39%, as determined via FRAP, while MC and RL displayed capacities comparable to BG. Antibacterial activity assays demonstrated that MC inhibited Escherichia coli with a minimum inhibitory concentration (MIC) of 12.5 mg/mL, lower than that of ampicillin, whereas CS was highly active against Staphylococcus aureus, with an MIC of 0.39 mg/mL, equivalent to the activity exhibited by tetracycline. Cytotoxicity assays confirmed that the extracts did not reduce human cell viability, supporting the potential of Chilean native shrubs as safe, natural sources of antioxidants and antimicrobials for food and pharmaceutical applications.

Plant growth-promoting rhizobacteria (PGPR) induce changes in the plant metabolism, improving plant growth under drought stress conditions by employing different mechanisms of interaction. In this study, two bacterial strains (Enterobacter sp. LHB11 and Bacillus sp. PIXIE) were evaluated in vitro regarding their PGPR traits, including the ACC-Deaminase enzyme activity. Both PGPR strains produced indole acetic acid (40.65–75.81 µg⁻¹mL⁻¹), exopolysaccharides (39.23–40.20 µg eq CR mL⁻¹), proline (61.5–106.1 mM), and volatile organic compounds. Furthermore, both solubilized phosphate (1.15–1.53 ratio, halo/colony) and fixed the atmospheric nitrogen. Only LHB11 showed ACC-Deaminase activity. Furthermore, both strains tolerated osmotic stress induced in liquid media with up to 20% of Polyethylene glycol-6000. In a drought stress pot experiment, both strains were applied to tomato roots, exposed to normal irrigation (100%) and drought stress (decreasing irrigation by 50%). The inoculation of both strains improved the plant growth parameters under stress conditions significantly, e.g., the root dry weight (+41.0–43.4%), while the proline content decreased to a level similar to the unstressed control. In addition, strain inoculation increased the total phenolic content and the antioxidant capacity measured as the inhibitions of the ABTS radical and as the reduction in ferric ions and increased the catalase and ascorbate peroxidase enzyme activity. The bacterial contribution to the changes in biochemical parameters is higher than in morphological parameters. At the same time, the strains modulate specific parameters depending on the stress condition, e.g., ABTS, catalase activity, and proline content. In conclusion, both strains Induced Systemic Tolerance (IST), regardless of their capacity to use the ACC-Deaminase mechanism, by modulating several mechanisms of plant response to drought stress. Our results showcase the relevance of considering the orchestration of several plant response mechanisms in order to fully assess the potential and efficiency of the plant–PGPR interaction under drought stress.

Nalca (Gunnera tinctoria Mol.) is traditionally consumed for its edible petioles and valued for medicinal properties associated with its bioactive compounds. In this study, natural deep eutectic solvents (NADESs) were synthesized and applied for the ultrasound-assisted extraction of phenolic compounds and alkaloids from Nalca leaves. NADES synthesis was confirmed using ¹H NMR, and their physicochemical properties were evaluated to assess their influence on extraction efficiency. The extracts showed total phenolic contents ranging from 6.8 to 142.6 mg GAE/g DW and total alkaloid contents ranging from 0.2 to 3.2 mg OXIE/g DW, depending on solvent composition. Antioxidant activity, evaluated using DPPH and FRAP assays, confirmed that most NADES extracts exhibited significant radical-scavenging and ferric-reducing capacities, generally correlating with phenolic content. The extraction yields obtained with specific NADES formulations were comparable or superior to those achieved with conventional solvents, demonstrating their efficiency. These results demonstrate that NADESs are effective and environmentally friendly alternatives to conventional solvents for extracting bioactive compounds from Nalca leaves. The physicochemical properties of NADESs enable the selective extraction of different metabolite classes, highlighting their potential for green extraction processes in food, nutraceutical, and pharmaceutical applications.