S. Aisling Aherne

Dietary flavonols: chemistry, food content, and metabolism.

The flavonols belong to a large group of compounds called flavonoids, which are diverse in their chemical structure and characteristics. Fruits, vegetables, and beverages such as tea and red wine are major sources of flavonols in the human diet. The daily consumption of flavonols is difficult to estimate because values depend on accurate assessment of feeding habits and flavonol content in foods. Food sources, dietary intakes, and bioavailability of flavonols are strongly influenced by variations in plant type and growth, season, light, degree of ripeness, food preparation, and processing, all of which are discussed. In the past few years, a number of studies on the absorption and metabolism of flavonols in humans have been published and the findings from these studies are reviewed. We do not discuss the health effects of flavonols.

Effects of plant extracts on antioxidant status and oxidant-induced stress in Caco-2 cells

Experimental evidence suggests that most herbs and spices possess a wide range of biological and pharmacological activities that may protect tissues against O2-induced damage. The objectives of the present study were: first, to determine the effects of plant extracts on the viability, membrane integrity, antioxidant status and DNA integrity of Caco-2 cells and second, to investigate the cytoprotective and genoprotective effects of these plant extracts against oxidative stress in Caco-2 cells. The plant extracts examined were rosemary (Rosmarinus officinalis L.), oregano (Origanum vulgare L.), sage (Salvia officinalis L.) and echinacea (Echinacea purpurea L.). Cell membrane integrity was assessed by the lactate dehydrogenase release assay. Viability was determined by the neutral red uptake assay (NRUA) and the concentration of compound that resulted in 50 % cell death (IC50) was calculated. Antioxidant status of the cells was assessed by measuring GSH content, catalase activity and superoxide dismutase activity. To examine their cytoprotective and genoprotective effects, Caco-2 cells were pre-treated with each plant extract for 24 h followed by exposure to H2O2. DNA damage was assessed by the comet assay and cell injury was determined by the NRUA. Rosemary was the most toxic (IC50 123 microg/ml) and echinacea the least toxic (IC50 1421 microg/ml). Sage was the only plant extract to affect the antioxidant status of the cells by increasing GSH content. Sage, oregano and rosemary protected against H2O2-induced DNA damage (olive tail moment and percentage tail DNA), whereas protection against H2O2-induced cytotoxicity was afforded by sage only.

Carotenoid Content of Commonly Consumed Herbs and Assessment of Their Bioaccessibility Using an In Vitro Digestion Model

Herbs are a rich source of bioactive phytochemicals such as carotenoids, which are known to exert various positive biological effects. However, there is very limited information in the literature regarding the content and bioavailability of carotenoids from commonly consumed herbs. Therefore, the objectives of the present study were first, to determine the carotenoid content of eight herbs namely basil (Ocimum basilicum), coriander (Coriandrum sativum), dill (Anethum graveolens), mint (Metha L.), parsley (Petroselinum crispum), rosemary (Rosmarinus officinalis), sage (Salvia officinalis), and tarragon (Artemisia dracunculus L.); and second, to assess carotenoid bioaccessibility from these herbs using a simulated human in vitro digestion model. Carotenoid bioaccessibility is defined as the amount of carotenoids transferred to micelles after digestion when compared with the original amount present in the food. The content of individual carotenoids varied significantly among the herbs tested. Carotenoid bioaccessibility varied from 0 to 42.8%. Basil and coriander, and their respective micelles, contained the highest levels of β-carotene, β-cryptoxanthin, and lutein + zeaxanthin. Our findings show that herbs are rich sources of carotenoids and that these foods can significantly contribute to the intake of bioaccessible carotenoids.

Cellular transport of lutein is greater from uncooked rather than cooked spinach irrespective of whether it is fresh, frozen, or canned

Lutein, a carotenoid found in significant levels in spinach, has attracted a great deal of attention owing to its reported function as a shield against the photooxidative effects of blue light. Therefore, the rationale of this study was to examine the effects of various processing and cooking methods on lutein bioavailability from spinach (Spinacia oleracea) using an in vitro digestion procedure coupled with the use of a human intestinal Caco-2 cell model. Fresh, frozen, and canned spinach were analyzed uncooked and after boiling or microwave cooking. Lutein content from the uncooked and cooked digested food (digestate) and appropriate micelles was determined. Micellarized lutein from the spinach samples was adjusted to 0.1 micromol/L and added to Caco-2 cells. Cellular uptake and secretion (cellular transport) of lutein were determined. Our results showed that digestate obtained from uncooked canned spinach had greater lutein content (P < .05) than uncooked fresh or frozen spinach. Microwave cooking, but not boiling, significantly lowered the lutein content of canned spinach digestate and micelles compared with their uncooked counterparts. Interestingly, there were no differences in the micellarization of lutein between the cooking and processing methods. Cellular transport of lutein was greater from uncooked spinach micelles compared with boiled or microwave-cooked spinach. To conclude, although the lutein content of digesta and micelles may have been modified, its micellarization was not significantly affected by any of the cooking or processing methods tested. In general, cellular transport of lutein was greatest in uncooked spinach irrespective of whether the spinach was fresh, frozen, or canned.

Growth inhibitory effects of casein hydrolysates on human cancer cell lines

The aim of this study was to investigate the effects of unhydrolysed/intact casein and eight different sodium casein hydrolysates (a-h) on the viability and growth of human cancer cell lines. Both human Jurkat T cells and Caco-2 cells were incubated with increasing concentrations of the test compounds (0.5-10% v/v) for 24 h. Cell viability was assessed using the MTT, lactate dehydrogenase (LDH) release and Trypan Blue assays. Cell growth was monitored using the MTT, Trypan Blue and Bromodeoxyuridine (BrdU) proliferation assays. Casein hydrolysates b, c and f had an inhibitory effect on the viability and growth of both cell lines. The casein hydrolysates did not negatively affect the membrane integrity of both Jurkat and Caco-2 cells. In Jurkat cells hydrolysates a and h had an inhibitory effect on DNA synthesis after 24 h, while in Caco-2 cells DNA synthesis was not affected. In conclusion, we found that the different casein hydrolysates had cell-specific effects which target particular functions within the cell. Overall, casein hydrolysates had no effect on membrane integrity while they had varied effects on mitochondrial activity and DNA synthesis in the different cell lines.

Bioactivity of Herb-Enriched Beef Patties

Interest exists in the manufacture of meat products with added functional ingredients to enhance consumer health. Because experimental evidence suggests that many herbs and spices, particularly those of the Lamiaceae family such as Salvia officinalis L. (sage) and Origanum vulgare L. (oregano), possess a wide range of biological and pharmacological activities, they represent promising functional ingredients for incorporation into meat and meat products. The present study aimed to determine the bioactivity of cooked beef patties that were enriched with or without sage or oregano extracts (1,200 microg/g). Cooked beef patties were subjected to an in vitro digestion procedure, and the resulting micelles isolated from the digested meats were added to human intestinal Caco-2 cells. The antioxidant potential (ferric reducing antioxidant power [FRAP] value) of enriched beef patties was significantly higher than the FRAP value of non-enriched beef patties, both before and after in vitro digestion. Cell viability significantly increased following treatment with certain concentrations of the micelle fractions from digested sage- or oregano-enriched beef patties. Pretreatment with micelles derived from sage- or oregano-enriched beef patties did not significantly protect against cell injury or DNA damage induced by H(2)O(2). However, micelles derived from digested sage-enriched beef patties (10% vol/vol) significantly increased cellular reduced glutathione (GSH) content. In addition, micelles derived from both sage- and oregano-enriched beef patties (10% vol/vol) significantly protected against H(2)O(2)-induced GSH depletion. Thus, it appears that sage and oregano exhibit some bioactivity within a meat system. Our findings suggest that herbal extracts have potential as possible functional ingredients in meat products.

Bioactive Properties of Wood Knot Extracts on Cultured Human Cells

Not all felled wood is converted to timber or pulp, with the remaining material being a rich source of relatively unexplored and unexploited potentially novel bioactive compounds. Therefore the potential bioactive effects of two softwood knot (the part of the branch encased in the tree stem) extracts--namely, Pinus banksiana Lamb. (Jack pine) and Picea sitchensis (Bong.) Carr. (Sitka spruce)--were investigated by (1) determining their effects on the viability and antioxidant status of human Jurkat T cells, (2) investigating potential cytoprotective and genoprotective effects against oxidative stress in cultured cells, and (3) assessing their effects on concanavalin A (ConA)-induced interleukin-2 (IL-2) production. Initially, both Jack pine knot and Sitka spruce knot extracts were shown to possess strong antioxidant activity as determined by the ferric reducing antioxidant power assay. When added to Jurkat cells, Jack pine knot extract was more toxic compared with Sitka spruce knot extract, with concentrations that resulted in 50% cell death of 153.0 microg/mL and 376.1 microg/mL, respectively. Supplementation of Jurkat cells with wood knot extracts did not affect their glutathione content or catalase activity. Pretreatment of Jurkat cells with Sitka spruce or Jack pine knot extracts protected against H(2)O(2)-induced cell injury. However, none of the extracts protected against H(2)O(2)-induced DNA damage. Jack pine knots, at a concentration of 30 microg/mL, significantly suppressed ConA-induced IL-2 production. Although total phenol content did not differ between the two extracts, gas chromatography analysis did show variation in the types of constituents present. Further research is warranted to elucidate the selective bioactive properties of these softwood knot extracts.

Lack of genoprotective effect of phytosterols and conjugated linoleic acids on Caco-2 cells

Much interest has focused on the cholesterol-lowering effects of phytosterols (plant sterols) but limited data suggests they may also possess anti-carcinogenic activity. Conjugated linoleic acids (CLA), sourced from meat and dairy products of ruminant animals, has also received considerable attention as a potential anti-cancer agent. Therefore, the aims of this project were to (i) examine the effects of phytosterols and CLA on the viability and growth of human intestinal Caco-2 cells and (ii) determine their potential genoprotective (comet assay), COX-2 modulatory (ELISA) and apoptotic (Hoechst staining) activities. Caco-2 cells were supplemented with the phytosterols campesterol, beta-sitosterol, or beta-sitostanol, or a CLA mixture, or individual CLA isomers (c10t12-CLA, t9t11-CLA) for 48 h. The three phytosterols, at the highest levels tested, were found to reduce both the viability and growth of Caco-2 cells while CLA exhibited isomer-specific effects. None of the phytosterols protected against DNA damage. At a concentration of 25 microM, both c10t12-CLA and t9t11-CLA enhanced (P<0.05) oxidant-induced, but not mutagen-induced, DNA damage. Neither the phytosterols nor CLA induced apoptosis or modulated COX-2 production. In conclusion, campesterol, beta-sitosterol, beta-sitostanol, c10t12-CLA, and t9t11-CLA were not toxic to Caco-2 cells, at the lower levels tested, and did not exhibit potential anti-carcinogenic activity.