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During kiwiberry production, different by-products are generated, including leaves that are removed to increase the fruit's solar exposure. The aim of this work was to extract bioactive compounds from kiwiberry leaf by employing microwave-assisted extraction (MAE). Compatible food solvents (water and ethanol) were employed. The alcoholic extract contained the highest phenolic and flavonoid contents (629.48 mg of gallic acid equivalents (GAE) per gram of plant material on dry weight (dw) (GAE/g dw) and 136.81 mg of catechin equivalents per gram of plant material on dw (CAE/g dw), respectively). Oppositely, the hydroalcoholic extract achieved the highest antioxidant activity and scavenging activity against reactive oxygen and nitrogen species (IC 50 = 29.10 μg/mL for O 2 •- , IC 50 = 1.87 μg/mL for HOCl and IC 50 = 1.18 μg/mL for • NO). The phenolic profile showed the presence of caffeoylquinic acids, proanthocyanidin, and quercetin in all samples. However, caffeoylquinic acids and quercetin were detected in higher amounts in the alcoholic extract, while proanthocyanidins were prevalent in the hydroalcoholic extract. No adverse effects were observed on Caco-2 viability, while the highest concentration (1000 µg/mL) of hydroalcoholic and alcoholic extracts conducted to a decrease of HT29-MTX viability. These results highlight the MAE potentialities to extract bioactive compounds from kiwiberry leaf.

Actinidia deliciosa and A. arguta fruits (kiwifruit and kiwiberry, respectively) are an excellent source of bioactive compounds. The aim of this paper is to valorize the fruits that are not commercialized (e.g. due to inadequate size or physical damage) in infusions and decoctions. The antioxidant activity, the scavenging activity against reactive species, the phenolic profile and the intestinal effects of infusions and decoctions of dehydrated fruits were evaluated and compared. Decoctions presented the highest antioxidant activity and a good ability to capture HOCl and NO. The phenolic composition of A. arguta present quinic acid, cis-caftaric acid and its derivatives, caffeoyl hexoside, luteolin glucuronide, quercetin derivatives and myristin, while A. deliciosa extracts were characterized by the presence of quinic acid, caffeic acid and its derivatives and caffeoyl hexoside. No adverse effects were observed on Caco-2 and HT29-MTX cells. Kiwiberry decoctions showed to be the best option to keep the fruits benefits., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Phenolic acids have been reported to play a role on the antioxidant activity and other important biological activities. However, as most polyphenolics in food products are either bound to cellular matrices or present as free polymeric forms, the way they are absorbed has not been totally clear until now. Hydrolytic enzymes may act to increase functionalities in polyphenolic-rich foods, enhancing the bioaccessibility of phenolic compounds and minerals from whole grains. The aim of this study was to evaluate the action of tannin acyl hydrolase (tannase) on the total phenols, phenolic acid profile, antioxidant capacity and in vitro bioaccessibility of phenolic acids found in whole rye flour (RF). Besides increasing total phenols and the antioxidant capacity, tannase treatment increased the amounts of ferulic, sinapic and vanillic acids identified in RF, evidencing a new type of feruloyl esterase catalytic action of tannase. Vanillic and sinapic acids in tannase-treated whole rye flour (RFT) were higher than RF after in vitro gastrointestinal digestion, and higher amounts of transported vanillic acid through the Caco-2 monolayer were detected in RFT. However, the bioaccessibility and the transport efficiency of RF phenolic acids were higher than RFT. Underutilized crops like rye and rye-derived products may be an important source of phenolic acids. The tannase biotransformation, even influencing the total phenolics and antioxidant capacity of RF, did not increase the bioaccessibility of phenolic acids under the experimental conditions of this study.

The chemical modification of anthocyanins (water-soluble pigments) into more lipophilic compounds is very important to expand their application in the food, medical and cosmetic industries. In this work, the synthesis of a pure malvidin-3-glucoside-oleic acid ester derivative was achieved by enzymatic catalysis. This approach allowed us to synthesize a novel compound, malvidin-3-O-(6''-oleoyl)glucoside (Mv3glc-OA), which was structurally characterized by mass spectrometry and for the first time by NMR spectroscopy. The enzymatic reaction revealed to be regioselective giving only one ester product. Antioxidant features of the malvidin-3-glucoside lipophilic derivative by means of DPPH, FRAP and lipid peroxidation assays were assessed, which confirmed that the structural modification of the genuine malvidin-3-glucoside into a more lipophilic compound did not compromise its antioxidant potential and protected more effectively a lipidic substrate from oxidation, which is an important insight for future technological applications.

In this study, the gastric transport efficiency of malvidin-3-glucoside and several derivatives was assayed on the MKN-28 cell model. The transport efficiency was found to increase for all compounds with the incubation time. Pyranoanthocyanins may slightly impair transport efficiency levels in comparison with native anthocyanins. Among the pyranoanthocyanin derivatives the presence of the carbonyl group and the absence of charge were important for the transport efficiency percentage of oxovitisin and apparently compensated the negative effect associated with the additional ring. Moreover, the antiproliferative properties of these compounds in the MCF-7 cancer cell line were assayed, oxovitisin being the most effective compound in inhibiting the proliferation of MCF-7 cells. Also, a kinetic incorporation of oxovitisin was assayed revealing that this pyranoanthocyanin is quickly incorporated into cells. This study confirms the importance of the natural micro-oxidative processes that occur during the ageing of anthocyanin-containing food and their impact on their bioavailability and bioactivity properties.

Anthocyanins are major flavonoids in many plant foods and have been related to health promotion. In the human organism anthocyanins are metabolised to different metabolites. One of the most important phase II reactions of flavonoids is the methylation of the catechol group. This feature is expected to have an effect on the antioxidant and antiproliferative properties of flavonoids including anthocyanins. In this work, delphinidin-3-glucoside, cyanidin-3-glucoside and petunidin-3-glucoside methylated metabolites were obtained by enzymatic hemi-synthesis. The compounds were identified as monomethylated products by HPLC-MS and NMR. The methylated metabolites were found to still retain significant radical scavenging activity and reducing activity, suggesting that they could act as potential antioxidants in vivo. The antiproliferative activity of the metabolites in comparison with the parental anthocyanins was also evaluated in three cancer cell lines by sulforhodamine B assay. The conjugation with methyl groups decreased or did not alter the antiproliferative effect of the original anthocyanin., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Phenolic compounds, namely, hydrolyzable tannins and low molecular weight phenolic compounds, were isolated and purified from Portuguese cork from Quercus suber L. Some of these compounds were studied to evaluate their antioxidant activity, including free-radical scavenging capacity (DPPH method) and reducing capacity (FRAP method). All compounds tested showed significant antioxidant activity, namely, antiradical and reducing properties. The antiradical capacity seemed to increase with the presence of galloyl groups. Regarding the reducing capacity, this structure-activity relationship was not so clear. These compounds were also studied to evaluate the growth inhibitory effect on the estrogen responsive human breast cancer cell line (ER+) MCF-7 and two other colon cancer cell lines (Caco-2 and HT-29). Generally, all the compounds tested exhibited, after a continuous exposure during a 48 h period, a dose-dependent growth inhibitory effect. Relative inhibitory activity was primarily related to the number of phenolic hydroxyl groups (galloyl and HHDP moieties) found in the active structures, with more groups generally conferring increased effects, except for HHDP-di-galloyl-glucose. Mongolicain B showed a greater potential to inhibit the growth of the three cell lines tested, identical to the effect observed with castalagin. Since these compounds are structurally related with each other, this activity might be based within the C-glycosidic ellagitannin moiety.

Considering the enological interest of cork, this study aimed to identify and quantify the phenolic compounds able to migrate from different classes (natural cork stoppers 'Flor' and 'Third' quality and microagglomerate cork stopper) of cork stoppers into bottled wine model solutions. Another aim was to evaluate some antioxidant and biological features of cork phenolics that migrated into the wine model solutions. The main phenolic acids and aldehydes detected were as follows: gallic and protocatechuic acid detected both around 3.5 mg/L and vanillin and protocatechuic aldehyde detected around 2.5 and 1.5 mg/L after 27 months of bottling, respectively. Trace amounts of more complex polyphenols, namely hydrolysable tannins (castalagin/vescalagin and mongolicain A/B), were also detected. Two antioxidant features of the wine model solutions bottled with different wine cork stoppers were studied, namely the antiradical capacity and the reducing capacity, being the natural cork stoppers the ones with the higher activities. The intestinal absorption of the compounds in each wine model solution after 27 months in bottled was evaluated. The simpler phenolic compounds were able to cross Caco-2 cell model. The antiproliferative activity of the same wine model solutions was also evaluated against gastric and breast cancer cells. All samples were active against the two cell lines, which highlight the possible health outcomes of wine sealed with cork stoppers. [ABSTRACT FROM AUTHOR]