Honeybee pollen loads result from the agglutination of pollen grains and salivary secretions of bees. The potential use of honeybee pollen as a food supplement greatly depends on its chemical composition, which varies depending on the botanical and geographical origin of the pollen grains. This study aimed to characterize the botanical origin, chemical composition, and antioxidant and antibacterial activities of honeybee pollen from the V Region of Chile. The introduced species Brassica rapa and Eschscholzia californica predominated in the bee pollen analyzed. The honeybee pollen extracts showed antioxidant and antibacterial properties, specifically against the pathogenic microorganism Streptococcus pyogenes. Quercetin and myricetin were found in all samples in large concentrations. The separation of pollen loads from a multifloral sample demonstrated that E. californica pollen loads are responsible for antibacterial activity. This sample also showed a high concentration of quercetin (304.8 mg/100 g of bee pollen). Based on the present results, honeybee pollen from the V Region of Chile has been found to exhibit antioxidant and antimicrobial activities. Furthermore, it is proposed to use quercetin as a quality indicator for honeybee pollen from this region of Chile. These results should help establish better quality control criteria for Chilean honeybee pollen and its potential use as a functional ingredient.

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Quercetin oxidation is generally believed to ultimately result in the loss of its antioxidant properties. To test this assertion, quercetin oxidation was induced, and after each of its major metabolites was identified and isolated by HPLC-DAD-ESI-MS/MS, the antioxidant (dichlorodihydrofluorescein oxidation-inhibiting) and cytoprotective (LDH leakage-preventing) properties were evaluated in Hs68 and Caco2 cells exposed to indomethacin. Compared to quercetin, the whole mixture of metabolites (Q) displayed a 20-fold greater potency. After resolution of Q into 12 major peaks, only one (peak 8), identified as 2,5,7,3',4'-pentahydroxy-3,4-flavandione or its 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone tautomer, could account for the antioxidant and cytoprotective effects afforded Q. Peak 8 exerted such effects at a 50 nM concentration, revealing a potency 200-fold higher than that of quercetin. The effects of peak 8 were seen regardless of whether it was added to the cells 40 min before or simultaneously with the oxygen-reactive species-generating agent, suggesting an intracellular ability to trigger early antioxidant responses. Thus, the present study is the first to reveal that in regard to the intracellular actions of quercetin, attention should be extended toward some of its oxidation products.

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Propolis has been proposed as a polyphenolic-rich natural product potentially able to be used for human consumption or even for medicinal proposes. To guarantee a minimum phenolic and flavonoid content and as consequence of their related-biological activities, international requirements of propolis quality are commonly applied. In this work we assessed phenolic and flavonoid contents of propolis; the antioxidant capacity (toward peroxyl radicals and hypochlorous acid); the ability to generate nitric oxide (NO); and, finally the antimicrobial activity of 6 propolis samples from the VI region of Chile. Our results show that the total phenolic and flavonoid content of propolis samples are not always in agreement with their polyphenolic-associated in vitro activities. For example, P03 and P06 samples showed the lowest (25 ± 4 GAE/g propolis) and the highest (105 ± 3 GAE/g propolis) total phenolic content, respectively. This was in agreement with flavonoid content and their Oxygen Radical Absorbance Capacity (ORAC) activity. However, this dependence was not observed toward HOCl, NO release and antimicrobial activity. Based on our results, we consider that, in order to guarantee the antioxidant or antimicrobial in vitro effects, the international regulations of propolis quality should contemplate the convenience of incorporating other simple analytical test such as ORAC or antimicrobial tests.

Artículo de publicación ISIPreservation, storage, and safe transport of samples are key factors affecting brown algal phlorotannin (phenolics) quantification, their extraction yield, and antioxidant activity. This is especially relevant when field sampling is carried out in remote areas. The objective of the present study was to evaluate and compare five preservation (frozen control, freeze-dried, silica-dried, oven-dried, and air-dried) and two extraction methods (Brapid^ and Btraditional^ extraction) of phlorotannins in the kelp Lessonia spicata (former Lessonia nigrescens). The antioxidant power of the samples treated with the different drying methods was compared through three different in vitro antioxidant assays: 2,2-diphenyl-1- picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) methods, employing fluorescein (ORAC-FL) and pyrogallol red (ORAC-PGR) as target molecules. The results of the testing methods indicated that freeze-drying afforded the best extraction yields of phlorotannins (18–30 % higher than control using frozen material) whereas concentrations from samples dried in silica and oven averaged between 17 and 20 % lower than control. The antioxidant activity of phlorotannins measured using the DPPH test decreased significantly in samples kept dried compared to that in control, with activities varying from 65 (freeze-dried) to 21 % (airdried). Accordingly, with ORAC-PGR and ORAC-FL indexes, sample preservation employing silica-drying or air-drying caused a high decrease of the antioxidant activity of polyphenols. No differences in both total phlorotannin concentration and antioxidant activity between the two extraction methods were found.FONDECY

The potential of 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3­(2H)-benzofuranone (BZF), a quercetin oxidation metabolite, and that of a BZF-rich onion peel aqueous extract (OAE) to protect Caco-2 monolayers against the oxidative stress (OS) and an increased permeability (IP) induced by five nonsteroidal anti-inflammatory drugs (NSAIDs) (indomethacin, diclofenac, piroxicam, ibuprofen, and metamizole) were investigated. Under identical OS conditions, the NSAIDs substantially differed in their ability to induce an IP and/or NF-kB activation. The OAE (100 nM BZF) protected in identical magnitude (84–86%) against OS but in a highly dissimilar manner against the IP (18–73%). While all NSAIDs activated NF-kB, the OAE prevented only that induced by indomethacin. Results reveal that the IP has no direct relationship with the OS and that with the exception of indomethacin, the prevention of NSAIDs-induced OS and/or NF-kB activation plays no fundamental role in the IP-protecting effect of OAE. These results warrant the in vivo evaluation of OAE against indomethacin-induced loss of intestinal barrier function.