Oxidative stress is an imbalance between levels of reactive oxygen species (ROS) and antioxidant enzymes. Compounds with antioxidant properties, such as coenzyme Q10 (CoQ10), can reduce cellular imbalance caused by an increase in ROS. CoQ10 participates in modulating redox homeostasis due to its antioxidant activity and its preserving mitochondrial functions. Thus, the present study demonstrated the protective effects of CoQ10 against oxidative stress and cytotoxicity induced by arsenic (As). Antioxidant capacity, formation of hydroperoxides, generation of ROS, and the effect on cellular viability of CoQ10, were investigated to determine the protective effect of CoQ10 against As and pro-oxidant compounds, such as zinc. Cell viability assays showed that CoQ10 is cytoprotective under cellular stress conditions, with potent antioxidant activity, regardless of the concentration tested. Zn, when used at higher concentrations, can increase ROS and show a pro-oxidant effect causing cell damage. The cytotoxic effect observed for As, Zn, or the combination of both could be prevented by CoQ10, without any decrease in its activity at cellular levels when combined with Zn.

Currently, teas and herbal infusions represent an important part of the human diet. Most contain phenolic compounds with high antioxidant activity, usually associated with human health protective functions. This attribute defines teas and infusions as nutraceutical foods. In Argentina, several native species are traditionally used for medical purposes. Some of those species are Larrea cuneifolia, Larrea nitida, Grindelia chiloensis, Pteromonnina dictyocarpa, Mandevilla laxa, and Monttea aphylla. The objectives of this study were to analyze the antioxidant power and the scavenging capacity of infusions obtained from those six medicinal plants, to characterize the phenolic profile, and to study in vitro their safety or cytotoxicity. Additionally, the potential use of two infusions as antioxidant additives in a food model was evaluated. The results indicated that the analyzed plant species are rich in phenolic acids (e.g., caffeic, ferulic, and chlorogenic acid), and flavonoids (e.g., quercetin and kaempferol), with high antioxidant power. The infusion blend obtained with G. chiloensis and L. cuneifolia exhibited the highest value of antioxidant capacity measured with the FRAP technique (193.4 μg EAA/mg DW). On the other hand, L. cuneifolia infusion showed the greatest antioxidant capacity determined by FRAP (131.9 ± 5.2 μg EAA/mg DW) and DPPH assays (0.453 mL/mg s). Additionally, L. cuneifolia infusion showed the highest phenolic content (232.8 μg GAE/mg DW) and flavonoid content (153.3 μg QE/mg DW). None of the infusions showed toxicity in mammalian cells, except for G. chiloensis. Furthermore, the L. cuneifolia and L. nitida infusions showed a high inhibitory effect on lipid oxidation in ground beef (55% and 51% at 4 days of storage, respectively). The results suggest that the studied infusions are safe and a rich source of antioxidants, which supports their use in traditional medicine. However, further exhaustive studies of G. chiloensis infusion are needed to ensure its safety, as it has shown cytotoxicity. Besides, it is worthwhile to advance the study of L. cuneifolia and L. nitida as sources of dietary antioxidants, due to their high antioxidant power and ability to protect against lipid peroxidation. Graphical Abstract

The Pehuén or Monkey puzzle tree (Araucaria araucana) is an evergreen coniferous tree, which has been historically used for social, medicinal, and nutritional purposes. We have recently showed the value of A. araucana seeds as a rich source of micronutrients and antioxidants. This endemic species present in a reduced area in Argentina and Chile is endangered because of the low germination rate and the overexploitation of its edible seeds. Thus, the massive extraction of its seeds is ecologically non-viable resulting in limited availability of its active metabolites. However, biotechnological approaches are attractive strategies of production of valuable metabolites and healthy specimens of endangered plants. The aim of this work was to develop a protocol for in vitro production of antioxidants derived from A. araucana seeds and to obtain healthy plants by optimized seed germination. Calli of Pehuén seeds were induced in Murashige and Skoog medium with different combinations of auxins and cytokinins, in light and dark conditions. Callus from embryonic axes developed in medium with 1 mg/l α-naphthaleneacetic acid and 1.5 mg/l 6-benzylaminopurine in light conditions had efficient biomass production, antioxidant activity, high phenolic, and flavonoid content and no cytotoxicity on mammalian cells. Additionally, 100 % germination was obtained in vitro and healthy plants were acclimatized to non-sterile conditions. In conclusion, in vitro culture of A. araucana could provide new and sustainable options for production of its valuable metabolites with possible therapeutic and nutritional uses. Also, optimized plant germination and acclimatization of endangered species can contribute to the preservation of pristine environments.

This study investigated the influence of solvent composition on the extraction efficiency and selectivity of phenolic compounds from the Amazonian fruits açaí (Euterpe oleracea) and bacaba (Oenocarpus bacaba). Six choline chloride-based natural deep eutectic solvents (NaDES), combined with different hydrogen bond donors (glycerol, 1,2-propanediol, citric acid, lactic acid, oxalic acid, and urea), were compared with acidified methanol. Extracts were evaluated for total phenolic content (TPC), total flavonoid content (TFC), and antioxidant capacity using FRAP, DPPH, and ORAC assays. In açaí, methanol exhibited the highest TPC and reducing capacity, whereas acid-based NaDESs enhanced phenolic recovery in a matrix-dependent manner. In bacaba, choline chloride–citric acid enhanced total phenolic recovery compared to methanol, highlighting matrix-dependent solvent performance. Differences among FRAP, DPPH, and ORAC responses reflected variations in phenolic composition rather than total concentration alone. HPLC-DAD analysis revealed solvent-selective enrichment of anthocyanins, chlorogenic acid, flavan-3-ols, and rutin, particularly with acid-based NaDES formulations. Molecular docking provided complementary mechanistic insight by indicating favorable interactions between major phenolics and polyphenol oxidase. Overall, the results indicate that choline chloride-based NaDESs can function as tunable extraction systems capable of modulating phenolic profiles in a matrix-dependent manner, representing promising alternatives to conventional organic solvents for phenolic recovery from Amazonian fruits.