Microbial Biotransformation of a Polyphenol-Rich Potato Extract Affects Antioxidant Capacity in a Simulated Gastrointestinal Model.

A multistage human gastrointestinal model was used to digest a polyphenol-rich potato extract containing chlorogenic acid, caffeic acid, ferulic acid, and rutin as the primary polyphenols, to assess for their microbial biotransformation and to measure changes in antioxidant capacity in up to 24 h of digestion. The biotransformation of polyphenols was assessed by liquid chromatography-mass spectrometry. Antioxidant capacity was measured by the ferric reducing antioxidant power (FRAP) assay. Among the colonic reactors, parent (poly)phenols were detected in the ascending (AC), but not the transverse (TC) or descending (DC) colons. The most abundant microbial phenolic metabolites in all colonic reactors included derivatives of propionic acid, acetic acid, and benzoic acid. As compared to the baseline, an earlier increase in antioxidant capacity (T = 8 h) was seen in the stomach and small intestine vessels as compared to the AC (T = 16 h) and TC and DC (T = 24 h). The increase in antioxidant capacity observed in the DC and TC can be linked to the accumulation of microbial smaller-molecular-weight phenolic catabolites, as the parent polyphenolics had completely degraded in those vessels. The colonic microbial digestion of potato-based polyphenols could lead to improved colonic health, as this generates phenolic metabolites with significant antioxidant potential.

Absorption and Metabolism of Phenolics from Digests of Polyphenol-Rich Potato Extracts Using the Caco-2/HepG2 Co-Culture System.

The bioactivity of dietary polyphenols depends upon gastrointestinal and hepatic metabolism of secondary microbial phenolic metabolites generated via colonic microbiota-mediated biotransformation. A polyphenol-rich potato extract (PRPE) containing chlorogenic, caffeic, and ferulic acids and rutin was digested in a dynamic multi-reactor gastrointestinal simulator of the human intestinal microbial ecosystem (GI model). Simulated digestion showed extensive degradation of the parent compounds and the generation of microbial phenolic metabolites. To characterize the transport and metabolism of microbial phenolic metabolites following digestion, a co-culture of intestinal Caco-2 and hepatic HepG2 cells was exposed to the PRPE-derived digests obtained from the colonic vessels. Following a 2 h incubation of the digesta with the Caco-2/HepG2 co-cultures, approximately 10-15% of ferulic, dihydrocaffeic, and dihydroferulic acids and 3-5% of 3-hydroxybenzoic, 3-hydroxyphenylpropionic, and coumaric acids were observed in the basolateral side, whereas 3-hydroxyphenylacetic acid, phenylpropanoic acid, and cinnamic acid were not detected. Subsequent HepG2 cellular metabolism led to major increases in ferulic, dihydrocaffeic, 3-hydroxyphenylpropionic, and coumaric acids ranging from 160-370%. These findings highlight the importance of hepatic metabolism towards the generation of secondary metabolites of polyphenols despite low selective Caco-2 cellular uptake of microbial phenolic metabolites.

Effects of Simulated Human Gastrointestinal Digestion of Two Purple-Fleshed Potato Cultivars on Anthocyanin Composition and Cytotoxicity in Colonic Cancer and Non-Tumorigenic Cells.

A dynamic human gastrointestinal (GI) model was used to digest cooked tubers from purple-fleshed Amachi and Leona potato cultivars to study anthocyanin biotransformation in the stomach, small intestine and colonic vessels. Colonic Caco-2 cancer cells and non-tumorigenic colonic CCD-112CoN cells were tested for cytotoxicity and cell viability after 24 h exposure to colonic fecal water (FW) digests (0%, 10%, 25%, 75% and 100% FW in culture media). After 24 h digestion, liquid chromatography-mass spectrometry identified 36 and 15 anthocyanin species throughout the GI vessels for Amachi and Leona, respectively. The total anthocyanin concentration was over thirty-fold higher in Amachi compared to Leona digests but seven-fold higher anthocyanin concentrations were noted for Leona versus Amachi in descending colon digests. Leona FW showed greater potency to induce cytotoxicity and decrease viability of Caco-2 cells than observed with FW from Amachi. Amachi FW at 100% caused cytotoxicity in non-tumorigenic cells while FW from Leona showed no effect. The present findings indicate major variations in the pattern of anthocyanin breakdown and release during digestion of purple-fleshed cultivars. The differing microbial anthocyanin metabolite profiles in colonic vessels between cultivars could play a significant role in the impact of FW toxicity on tumor and non-tumorigenic cells.

Avaliação de Compostos Bioativos, Composição Físico-Química e Atividade Antioxidante In Vitro da Farinha de Berinjela / Assessment of Bioactive Compounds, Physicochemical Composition, and In Vitro Antioxidant Activity of Eggplant Flour

Fundamento: A berinjela (Solanum melongena) é um fruto de consumo mundial. Seu processamento em forma de farinha é uma maneira de evitar perdas e aproveitar suas características nutricionais. Objetivos: Este estudo avaliou a composição físico-química (umidade, proteínas, lipídeos, fibra bruta, carboidratos, minerais, niacina, saponinas, acidez titulável, fibra alimentar e fenóis totais) da farinha de berinjela preparada a partir do fruto inteiro desidratado em estufa. Métodos: Avaliou-se a atividade antioxidante in vitro usando os seguintes ensaios: radical 2,2-difenil-1-picrilhidrazila (DPPH); poder antioxidante de redução do ferro (FRAP); e análise de polifenóis com Cromatografia Líquida de Alta Eficiência (CLAE - ácido clorogênico, ácido cafeico, ácido ferúlico e rutina). Resultados: Verificou-se a presença de: 23,09% de carboidratos; 13,34% de proteínas; 1,85% de lipídeos; 39,19% de fibras totais; 1.540 mg/100 g de compostos fenólicos solúveis totais; 840 mg/100 g de saponinas; minerais (potássio, magnésio, cobre, ferro, zinco, manganês); e niacina. Observou-se atividade antioxidante in vitro para DPPH (455,6 mg de ácido ascórbico/100 g) e FRAP (486,8 mg de ácido ascórbico/100 g). A CLAE determinou a presença de ácido ascórbico, tirosina e ácidos fenólicos (ácido clorogênico, ácido cafeico e ácido ferúlico). Conclusão: A farinha de berinjela tem alto teor de fibra além de bom teor de compostos fenólicos e saponinas com importante capacidade antioxidante observada através de ensaios in vitro. A farinha de berinjela é uma boa opção para ser adicionada à dieta da população, devido aos seus potenciais benefícios à saúde

Background: The eggplant (Solanum melongena) is a fruit of world consumption. Its processing in the form of flour is a way to avoid losses and to take advantage of its nutritional characteristics. Objective: This study assessed the physicochemical composition (moisture, proteins, lipids, crude fiber, carbohydrates, minerals, niacin, saponins, titratable acidity, dietary fiber, and total phenols) of eggplant flour prepared from the whole fruit dehydrated in an oven. Methods: In vitro antioxidant activity was assessed using the following methods: 2.2-diphenyl-1-picrylhydrazyl radical (DPPH); Ferric Reducing/ Antioxidant Power (FRAP); and analysis of polyphenols using HPLC (chlorogenic acid, caffeic acid, ferulic acid, and rutin). Results: It was possible to observe: 23.09% carbohydrates; 13.34% proteins; 1.85% lipids; 39.19% total fibers; 1,540 mg/100 g total soluble phenolic compounds; 840 mg/100 g saponins; minerals (potassium, magnesium, copper, iron, zinc, manganese); and niacin. In vitro antioxidant activity was observed through DPPH (455.6 mg ascorbic acid/100 g) and FRAP (486.8 mg ascorbic acid/100 g). The HPLC method determined the presence of ascorbic acid, tyrosine, and phenolic acids (chlorogenic acid, caffeic acid, and ferulic acid). Conclusion: The eggplant flour had great fiber content in addition to good content of phenolic compounds and saponins with important antioxidant capacity observed through in vitro assays. As a result, eggplant flour is a good addition to the diet of the population, since it can bring potential health benefits

Biotransformation of polyphenols in a dynamic multistage gastrointestinal model.

A multi-reactor gastrointestinal model was used to digest a mixture of pure polyphenol compounds, including non-flavonoid phenolic acids (chlorogenic acid, caffeic acid, ferulic acid) and a flavonoid (rutin) to identify phenolic metabolites and short chain fatty acids (SCFAs) and compare relative antioxidant capacities following a 24h digestion. Biotransformation of these polyphenols occurred in the colonic compartments generating phenylpropionic, benzoic, phenylacetic and cinnamic acids. Total SCFAs increased in all colonic vessels with a rise in the proportion of propionic to acetic acid. Antioxidant capacity increased significantly in all compartments, but first in the stomach, small intestine and ascending colon. After 24h, the colonic vessels without parent polyphenols, but containing new metabolites, had antioxidant capacities similar to the stomach and small intestine, containing parent compounds. Biotransformation of pure polyphenols resulted in different phenolic metabolite and SCFAs profiles in each colonic segment, with important health implications for these colonic compartments.

Inhibitory effects of apple peel polyphenol extract on the formation of heterocyclic amines in pan fried beef patties.

The efficacy of polyphenol-rich dried apple peel extract (DAPP) to inhibit the formation of heterocyclic aromatic amines (HCAs) during frying of beef patties was assessed after DAPP was applied at 0.1, 0.15 and 0.3% (w/w) either on the surface of the patties or mixed inside the patty prior to frying. 2-Amino-3,8-dimethylimidazo[4,5f]quinoxaline (MeIQx), 2-amino-1-ethyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,4,8-dimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) were quantified after frying. HCA concentrations decreased (p<0.05) upon both surface and mixed applications of DAPP at all of the tested doses. Surface application of 0.3% DAPP showed greater (p<0.05) inhibitory effects on HCA formation by 68% for MeIQx, 56% for 4,8-DiMeIQx and 83% for PhIP as opposed to 41%, 21% and 60% respectively, for the mixed DAPP application of 0.3%. The present study results indicate that surface application of DAPP in meat preparation prior to pan-frying can be a useful approach to minimize the formation of genotoxic HCAs in fried beef patties.

Biotransformation of anthocyanins from two purple-fleshed sweet potato accessions in a dynamic gastrointestinal system.

Cooked, milled purple-fleshed sweet potato (PFSP) accessions, PM09.812 and PM09.960, underwent digestion in a dynamic human gastrointestinal (GI) model that simulates gut digestive conditions to study the bioaccessibility and biotransformation of anthocyanins. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry showed accession-dependent variations in anthocyanin release and degradation. After 24h, more anthocyanin species were detected in the small intestinal vessel relative to other vessels for accession PM09.960 whereas more species appeared in the ascending colonic vessel for accession PM09.812. The ferric reducing antioxidant power was increased in the small intestinal vessel for PM09.960 and in the ascending colonic vessel for accession PM09.812, corresponding to the appearance of a majority of anthocyanins for each accession. These results show that intestinal and colonic microbial digestion of PFSP leads to an accession-dependent pattern for anthocyanin bioaccessibility and degradation.

Cd and Ni transport and accumulation in the halophyte Sesuvium portulacastrum: implication of organic acids in these processes.

The implication of organic acids in Cd and Ni translocation was studied in the halophyte species Sesuvium portulacastrum. Citric, fumaric, malic, and ascorbic acids were separated and quantified by HPLC technique in shoots, roots and xylem saps of plants grown on nutrient solutions added with 50 µM Cd, 100 µM Ni and the combination of 50 µM Cd + 100 µM Ni. Results showed that Cd had no significant impact on biomass production while Ni and the combination of both metals drastically affected plant development. Cadmium and Ni concentrations in tissues and xylem sap were higher in plants subjected to individual metal application than those subjected to the combined effect of Cd and Ni suggesting a possible competition between these metals for absorption. Both metals applied separately or in combination induced an increase in citrate concentration in shoots and xylem sap but a decrease of this concentration in the roots. However, a minor relationship was observed between metal application and fumaric, malic, and ascorbic acids. Both observations suggest the implication of citric acid in Cd, Ni translocation and shoot accumulation in S. portulacastrum. The relatively high accumulation of citric acid in xylem sap and shoot of S. portulacastrum could be involved in metal chelation and thus contributes to heavy metal tolerance in this species.

High Hydrostatic Pressure Pretreatment of Whey Protein Isolates Improves Their Digestibility and Antioxidant Capacity.

Whey proteins have well-established antioxidant and anti-inflammatory bioactivities. High hydrostatic pressure processing of whey protein isolates increases their in vitro digestibility resulting in enhanced antioxidant and anti-inflammatory effects. This study compared the effects of different digestion protocols on the digestibility of pressurized (pWPI) and native (nWPI) whey protein isolates and the antioxidant and anti-inflammatory properties of the hydrolysates. The pepsin-pancreatin digestion protocol was modified to better simulate human digestion by adjusting temperature and pH conditions, incubation times, enzymes utilized, enzyme-to-substrate ratio and ultrafiltration membrane molecular weight cut-off. pWPI showed a significantly greater proteolysis rate and rate of peptide appearance regardless of digestion protocol. Both digestion methods generated a greater relative abundance of eluting peptides and the appearance of new peptide peaks in association with pWPI digestion in comparison to nWPI hydrolysates. Hydrolysates of pWPI from both digestion conditions showed enhanced ferric-reducing antioxidant power relative to nWPI hydrolysates. Likewise, pWPI hydrolysates from both digestion protocols showed similar enhanced antioxidant and anti-inflammatory effects in a respiratory epithelial cell line as compared to nWPI hydrolysates. These findings indicate that regardless of considerable variations of in vitro digestion protocols, pressurization of WPI leads to more efficient digestion that improves its antioxidant and anti-inflammatory properties.

Extract of Irish potatoes (Solanum tuberosum L.) decreases body weight gain and adiposity and improves glucose control in the mouse model of diet-induced obesity.

Both sexes of mice were fed a high fat diet (HFD) for 10 weeks without and with polyphenolic-rich potato extracts (PRPE) of cultivars Onaway and Russet Burbank. PRPE attenuated weight gain in male and female mice by as much as 63.2%, which was associated mostly with a reduction in adiposity. Mice receiving PRPE showed enhanced capacity for blood glucose clearance. Sex differences regarding the impact of HFD and PRPE on plasma levels of insulin, ghrelin, leptin, gastric inhibitory peptide, and resistin were noted. PRPE may serve as part of a preventative dietary strategy against the development of obesity and type 2 diabetes.

Some Canadian-grown potato cultivars contribute to a substantial content of essential dietary minerals.

Potato consumption provides significant dietary contributions to several essential minerals, but the effects of cultivar and planting site are not well-understood. The mineral content of 16 cultivars, grown at 5 locations, was measured using inductively coupled plasma-optical emission spectroscopy and evaluated on a per serving basis for percent recommended daily intake (% RDI), emphasizing some minerals where global deficiencies are common (calcium, iron, selenium, and zinc). Discriminant analysis showed that both genotype and growing location were important. Differences in mineral content occurred between cultivars at each site, specific cultivars at different sites, and collectively between sites. 'Freedom', 'Yukon Gold', and particularly the very stable mineral source 'Russet Burbank' contributed most to the % RDI for minerals. One serving per day of these cultivars provides a significant contribution to the % RDI for the macrominerals magnesium, phosphorus, and potassium and the trace minerals copper, iron, selenium, and zinc.

Microwave-assisted extraction of phenolic antioxidants from potato peels.

A response surface method was used to optimize the microwave-assisted extraction parameters such as extraction time (t) (min), solvent (methanol) concentration (S) (v/v) and microwave power level (MP) for extraction of antioxidants from potato peels. Max. total phenolics content of 3.94 mg g⁻¹ dry weight (dw) was obtained at S of 67.33%, t of 15 min and a MP of 14.67%. For ascorbic acid (1.44 mg g⁻¹ dw), caffeic acid (1.33 mg g⁻¹ dw), ferulic acid (0.50 mg g⁻¹ dw) max contents were obtained at S of 100%, t of 15 min, and MP of 10%, while the max chlorogenic acid content (1.35 mg g⁻¹ dw) was obtained at S of 100%, t of 5 min, and MP of 10%. The radical scavenging activity of the extract was evaluated by using the DPPH assay and optimum antioxidant activity was obtained at S of 100%, t of 5 min, and MP of 10%.

Low dietary boron reduces parasite (nematoda) survival and alters cytokine profiles but the infection modifies liver minerals in mice.

Although boron (B) is an essential trace mineral, any interactions that it may have with gastrointestinal (GI) nematode infections are unknown. This study explored whether low dietary B would: 1) alter survival or reproduction of Heligmosomoides bakeri (Nematoda); 2) modify the resulting cytokine response to this parasitic infection; or 3) influence liver mineral concentrations in the infected host. Balb/c mice were fed either a low-B (0.2 microg B/g), marginal (2.0 microg B/g), or control (12.0 microg B/g) diet. Diets commenced 3 wk before a primary infection and were fed for 4 wk (primary infection protocol) and 8-9 wk (challenge infection protocol). Mice were killed 6 d post-primary infection (d6ppi), or dewormed then reinfected (challenge infection protocol) and killed 14 or 21 d post-challenge infection (d14pci or d21pci, respectively). Low and marginal dietary B intakes impaired survival of the parasite, reduced intestinal inflammation, and modulated a broad range of cytokines and chemokines despite similar liver B concentrations in diet groups. Compared with control mice, cytokine production was lower following low and marginal B intakes at d6ppi but was elevated at d21pci. Serum alkaline phosphatase was higher at d6ppi than at d14pci and d21pci. Compared with d14pci, liver zinc, iron, and B concentrations were reduced at d21pci when worm numbers were also lower, whereas concentrations of sodium, potassium, molybdenum, chromium, and sulfur were higher. This study shows that parasite survival and cytokine and inflammatory responses are modified by dietary B intake but indicates that a GI nematode infection alters liver mineral concentrations.

Lipase-catalyzed transesterification of dihydrocaffeic acid with flaxseed oil for the synthesis of phenolic lipids.

Lipase-catalyzed transesterification reaction of dihydrocaffeic acid (DHCA) with flaxseed oil in organic solvent media was investigated. Using equal molar concentration of DHCA and flaxseed oil, only phenolic monoacylglycerols were obtained with a transesterification yield (TY) of 18.9%. A 1:4 DHCA to flaxseed oil ratio resulted in the production of both phenolic mono and diacylglycerols, with TY of 39.6 and 27.8%, respectively. On the other hand, when 1:8 ratio of DHCA to flaxseed oil was used, the TY of phenolic diacylglycerols (46.0%) was higher than that of the phenolic monoacylglycerols (33.3%). The TY of phenolic diacylglycerols increased from 25.1 to 55.8%, when the ratio of the hexane/2-butanone reaction medium was changed from 65:35 to 85:25 (v/v); however, the TY of phenolic monoacylglycerols decreased slightly from 34.0 to 31.8%. The relative proportion of the C(18:3)n-3 was higher in the phenolic mono and diacylglycerols, 64.9 and 59.5%, respectively, as compared to the original flaxseed oil, 53.1%. The radical scavenging ability of phenolic lipids was significant; however, it was about half than that of alpha-tocopherol.

Lipase-catalyzed esterification of selected phenolic acids with linolenyl alcohols in organic solvent media.

Lipase-catalyzed esterification of selected phenolic acids with linolenyl alcohols was investigated in selected organic solvent media. The enzyme activity for the esterification of dihydrocaffeic acid with linolenyl alcohol in solvent mixtures of hexane/2-butanone of 75:25 (v/v) and 65:35 (v/v) was 0.88 and 0.47 micromol of esterified dihydrocaffeic acid/(g of solid enzyme.min), respectively, with a corresponding esterification yield of 76 and 58%, respectively. However, the esterification of ferulic acid with linolenyl alcohol in the reaction medium of hexane/2-butanone of 65:35 (v/v) resulted in a low yield (16%). Using the reaction medium of hexane/2-butanone of 75:25 (v/v), an increase in linolenyl alcohol concentration with a concomitant use of a constant amount of dihydrocaffeic acid resulted in an increase in esterification yield. The highest esterification yield of 99% was obtained with a ratio of dihydrocaffeic acid to linolenyl alcohol of 1:8 after 7 d of reaction. Biosynthesis of the end product, linolenyl dihydrocaffeate, was confirmed by electrospray ionization mass spectroscopy structural analysis; the ester product demonstrated an antiradical activity close to that of alpha-tocopherol.