Honeybee pollen (HBP) chemical composition is highly variable conforming to the floral and geographical origin of the pollen grains. The beneficial effects and functional properties of the HBP are well-known and have been mainly attributed to their high content of antioxidant polyphenols. In this work, twelve HBPs samples from the Southern region of Chile (X Región de Los Lagos) were characterized for the first time according to their botanical origin, phenolic composition, and antioxidant activity. The in vitro gastrointestinal digestion assay was done to simulate the human upper digestive tract. Selected honeybee pollen extracts (HBPEs) were assessed as bioaccessible fractions during an in vitro gastrointestinal digestion. Contents of phenolic compounds, antioxidant capacity, and recovery index of quercetin, myricetin, and cinnamic acid were monitored in different steps of gastrointestinal digestion. Furthermore, the protective effect of in vitro digested HBP towards DNA damage induced by peroxyl radicals was evaluated. The introduced species Brassica rapa L. (Brassicaceae), Lotus pedunculatus Cav. (Fabaceae), and Ulex europaeus L. (Fabaceae) predominated in all the HBPs analyzed, while the native species Buddleja globosa Hope (Scrophulariaceae), Luma apiculata (DC.) Burret (Myrtaceae), Embothrium coccineum J.R. Forst. & G. Forst. (Proteaceae) and Eucryphia cordifolia Cav. (Cunoniaceae) appeared less frequently. The content of polyphenols and antioxidant capacity in HBPEs achieved full bioaccessibility at the end of the intestinal digestion step. However, results obtained by a state-of-the-art technique (i.e. HPLC-DAD) demonstrated relatively low values of bioaccessible quercetin and cinnamic acid after the digestion process. In contrast, myricetin showed a high bioaccessibility in the intestinal digestion steps. The protective effect of in vitro digested HBP towards DNA damage induced by peroxyl radicals showed promising results (up to 91.2% protection). In conclusion, HBPs from the X Region de Los Lagos are rich sources of phenolic antioxidants that protect DNA from strand breakage. Therefore, the potential of HBPEs in preventing gastric and/or intestinal cancer should be further considered.

Tissue accumulation of L-phenylalanine (Phe) is the biochemical hallmark of human phenylketonuria (PKU), an inherited metabolic disorder clinically characterized by mental retardation and other neurological features. The mechanisms of brain damage observed in this disorder are poorly understood. In the present study we investigated some oxidative stress parameters in the brain of rats with experimental hyperphenylalaninemia. Chemiluminescence, total radical-trapping antioxidant potential (TRAP), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities were measured in the brain of the animals. We observed that chemiluminescence is increased and TRAP is reduced in the brain of hyperphenylalaninemic rats. Similar data were obtained in the in vitro experiments using Phe at various concentrations. CAT activity was significantly inhibited by Phe in vitro and in vivo, whereas GSH-Px activity was reduced in vivo but not in vitro and SOD activity was not altered by any treatment. The results indicate that oxidative stress may be involved in the neuropathology of PKU. However, further studies are necessary to confirm and extend our findings to the human condition and also to determine whether an antioxidant therapy may be of benefit to these patients.

Nonalcoholic fatty liver disease (NAFLD) is a major cause of morbidity and mortality worldwide. Additional therapies using functional foods and dietary supplements have been investigated and used in clinical practice, showing them to be beneficial. Honeybee pollen from Chile has shown a large concentration of phenolic compounds and high antioxidant activity. In this work, we characterized twenty-eight bee pollen extracts from the central zone of Chile according to botanical origin, phenolic profile, quercetin concentration, and antioxidant activity (FRAP and ORAC-FL). Our results show a statistically significant positive correlation between total phenolic content and antioxidant capacity. Selected samples were evaluated on the ability to reverse the steatosis in an in vitro cell model using Hepa1-6 cells. The pollen extracts protected Hepa1-6 cells against oxidative damage triggered by 2,2'-azo-bis(2-amidinopropane) dihydrochloride (AAPH)derived free radicals. This effect can be credited to the ability of the phenolic compounds present in the extract to protect the liver cells from chemical-induced injury, which might be correlated to their free radical scavenging potential. Additionally, bee pollen extracts reduce lipid accumulation in a cellular model of steatosis. In summary, our results support the antioxidant, hepatoprotective, and anti-steatosis effect of bee pollen in an in vitro model.

Hypochlorite is a strong oxidant able to induce deleterious effects in biological systems. The goal of this work was to investigate the use of PGR and PYR as probes in assays aimed at evaluating antioxidant activities towards hypochorite and apply it to plant extracts employed in Chilean folk medicine. The consumption of PGR and PYR was evaluated from the decrease in the visible absorbance and fluorescence intensity, respectively. Total phenolic content was determined by the Folin Ciocalteau assay. PGR and PYR react with hypochlorite with different kinetics, being considerably faster the consumption of PGR. Different stoichiometric values were also determined: 0.7 molecules of PGR and 0.33 molecules of PYR were bleached per each molecule of added hypochlorite. Both probes were protected by antioxidants, but the rate of PGR bleaching was too fast to perform a kinetic analysis. For PYR, the protection took place without changes in its initial consumption rate, suggesting a competition between the dye and the antioxidant for hypochlorite. Plant extracts protected PYR giving a PYR-HOCl index that follows the order: Fuchsia magellanica ≈ Marrubium vulgare ≈ Tagetes minuta > Chenopodium ambrosoides ≈ Satureja montana > Thymus praecox. Based on both the kinetic data and the protection afforded by pure antioxidants, we selected PYR as the best probe. The proposed methodology allows evaluating an antioxidant capacity index of plant extracts related to the reactivity of the samples towards hypochlorite.

Chickpeas are rich sources of bioactive compounds such as phenolic acids, flavonoids, and isoflavonoids. However, the contribution of insoluble-bound phenolics to their antioxidant properties remains unclear. Four varieties of chickpeas were evaluated for the presence of soluble (free and esterified) and insoluble-bound phenolics as well as their antiradical activity, reducing power and inhibition of peroxyl-induced cytotoxicity in human HuH-7 cells. In general, the insoluble-bound fraction showed a higher total phenolic content. Phenolic acids, flavonoids, and isoflavonoids were identified and quantified by UPLC-MS/MS. Taxifolin was identified for the first time in chickpeas. However, m-hydroxybenzoic acid, taxifolin, and biochanin A were the main phenolics found. Biochanin A was mostly found in the free fraction, while m-hydroxybenzoic acid was present mainly in the insoluble-bound form. The insoluble-bound fraction made a significant contribution to the reducing power and antiradical activity towards peroxyl radical. Furthermore, all extracts decreased the oxidative damage of human HuH-7 cells induced by peroxyl radicals, thus indicating their hepatoprotective potential. This study demonstrates that the antioxidant properties and bioactive potential of insoluble-bound phenolics of chickpeas should not be neglected.