Geographical location has greater impact on carotenoid content and bioaccessibility from tomatoes than variety

The suggested health benefits of consuming tomatoes and tomato-based products have been attributed, in part, to the carotenoids present in these foods. Therefore, the objectives of the present study were to (i) analyse carotenoid content and bioaccessibility from different tomato (Lycopersicon esculentum L.) types namely cherry, plum, round, and certain tomatoes-on-the-vine; and (ii) determine if geographical location (Ireland vs Spain) influenced the content and bioaccessibility of carotenoids in tomatoes of the same variety. Carotenoid bioaccessibility is defined as the amount of ingested carotenoids that, after digestion, are available for absorption by intestinal cells. Differences were seen in carotenoid content and bioaccessibility between the different tomato types tested. For instance, Irish round high-lycopene tomatoes contained the greatest amounts of lycopene and lutein but lowest levels of beta-carotene compared with the other Irish tomatoes. Furthermore, the content and bioaccessibility of carotenoids that were sourced from Ireland and Spain also varied greatly. Spanish tomatoes were generally superior in the content, bioaccessibility, and micelle content of carotenoids. To conclude, our findings suggest that geographical location, rather than the type of tomato, seems to have a more pronounced effect on carotenoid bioaccessibility from tomatoes.

Micellarisation of carotenoids from raw and cooked vegetables

The efficiency of carotenoid micellarisation from plant foods can be used as an effective tool for the initial screening of carotenoid bioavailability. Therefore, the objectives of the present study were to assess the effects of cooking on the micellarisation of beta-carotene, lycopene, beta-cryptoxanthin and lutein from courgette (zucchini), red pepper and tomato; and, to a minor extent, investigate uptake of lutein by Caco-2 cells from micellar fractions obtained from raw and cooked courgettes. Both raw and cooked vegetables were subjected to an in vitro digestion procedure. beta-Carotene levels were significantly decreased in the digesta from each vegetable after boiling, grilling, microwave-cooking, or steaming, however all of the cooking methods enhanced beta-carotene transfer to micelles. Carotenoid micellarisation ranged from 1.7% to 100% depending on the food, carotenoid, and the cooking method tested. Grilling and microwave-cooking were generally the most detrimental on the transfer of xanthophyll carotenoids, namely beta-cryptoxanthin, to the micelles. Caco-2 cells absorbed greater amounts of lutein from the micelles of microwave-cooked courgettes than those that were raw, boiled, grilled, or steamed. Depending on the cooking methods used, carotenoid retention as well as micellarisation varied for each carotenoid among the different vegetables and different carotenoids present in each particular food.

Lack of effect of the flavonoids, myricetin, quercetin, and rutin, on repair of H2O2-induced DNA single-strand breaks in Caco-2, Hep G2, and V79 cells

In the present study the effects of three flavonoids on the repair of H2O2-induced DNA strand breaks were investigated in Caco-2, Hep G2, and V79 cells. At the concentrations used, myricetin, quercetin, rutin, and H2O2 did not significantly affect cell viability in all the cell lines. Catalase activity was measured in V79 cells and was found to be considerably lower than activities previously measured in Caco-2 and Hep G2 cells. Cells were exposed to 50 microM H2O2 for 0.5 hour at 37 degrees C. After treatment, DNA strand break repair in H2O2-treated cells was monitored at various time points over a 48-hour period using the alkaline single-cell gel electrophoresis assay. Caco-2 cells repaired faster than Hep G2 cells, which repaired considerably faster than V79 cells. Preincubation with 50 microM quercetin for 24 hours significantly decreased the extent of H2O2-induced DNA single-strand breaks throughout repair time points in Caco-2 cells (p < 0.05), but not in Hep G2 cells. Myricetin (50 microM) and rutin (50 microM) had no effect on repair in Caco-2 and Hep G2 cells. Preincubation for 10 hours with quercetin and rutin, but not myricetin, significantly decreased the initial extent of DNA damage induced by H2O2 in V79 cells (p < 0.05). However, from the results of this study, none of the three flavonoids increased the rate of repair of strand breaks in any of the cell types.

Mechanism of protection by the flavonoids, quercetin and rutin, against tert-butylhydroperoxide- and menadione-induced DNA single strand breaks in Caco-2 cells

Protection by the flavonoids, quercetin and rutin, against tert-butylhydroperoxide (tert-BOOH)- and menadione-induced DNA single strand breaks was investigated in Caco-2 cells. Both tert-BOOH and menadione induced DNA single strand breaks in a concentration-dependent manner. Pre-incubation of Caco-2 cells with either quercetin or rutin for 24 h significantly decreased the formation of DNA single strand breaks evoked by tert-BOOH (P <.05). Iron chelators, 1,10-phenanthroline (o-Phen) and deferoxamine mesylate (DFO), also protected against tert-BOOH-induced DNA damage, whereas butylated hydroxytoluene (BHT) had no effect. Quercetin, and not rutin, decreased the extent of menadione-induced DNA single strand breaks. DFO and BHT, and not o-Phen, protected against menadione-induced DNA strand break formation (P <.05). From the results of this study, iron ions were involved in tert-BOOH-induced DNA single strand break formation in Caco-2 cells, whereas DNA damage evoked by menadione was far more complex. We demonstrated that the flavonoids, quercetin and rutin, protected against tert-BOOH-induced DNA strand breaks by way of their metal ion chelating mechanism. However, quercetin, and not rutin, protected against menadione-induced DNA single strand breaks by acting as both a metal chelator and radical scavenger.

Cytotoxicity, genotoxicity and oxidative reactions in cell-culture models: modulatory effects of phytochemicals

Much research effort has focused on the identification of phytochemicals in fruit and vegetables which exert beneficial effects. Our research examines modulatory effects of phytochemicals on cytotoxicity, genotoxicity and oxidative reactions in cell systems. Two examples of our studies are discussed. First, the potential beneficial effects of flavonoids are demonstrated. Flavonoids are reported to exhibit a wide variety of biological effects, including antioxidant and free-radical-scavenging activities. The aim of the study was to determine if flavonoids could protect against H2O2-induced DNA damage, as measured by the comet assay, in Caco-2 and HepG2 cells. Both cell lines were supplemented with increasing concentrations of myricetin, quercetin and rutin for 24 h followed by exposure to H2O2 (50 microM) for 30 min. Exposure to H2O2 for 30 min at 37 degrees C resulted in significant DNA damage and pre-incubation with the flavonoids before H2O2 exposure significantly (P <0.05) protected Caco-2 and HepG2 cells against H2O2-induced DNA damage. Secondly, we illustrate the use of cellular models to study oxysterol-induced toxicity. Oxysterols are generated during the cooking and processing of foods and may be produced endogenously by the oxidation of membrane lipids. Recent findings suggest that oxysterols may modulate cytotoxicity by exerting effects on the induction of apoptosis. 7beta-Hydroxycholesterol (7beta-OHC) and 25-hydroxycholesterol, both of which are commonly found in foods, were investigated for their abilities to induce apoptosis in a human monocytic blood cell line, U937, and in the human hepatoma cell line, HepG2 cells. U937 and HepG2 cells were incubated for up to 48 h with 30 microM oxysterol. 7beta-OHC induced apoptosis in U937 cells as measured by non-random DNA fragmentation, condensed and fragmented nuclei, and the generation of hypodiploid cells. In contrast, oxysterols may induce cell death by a different mechanism in the hepatoma cells, possibly by necrosis.

Protection by the flavonoids myricetin, quercetin, and rutin against hydrogen peroxide-induced DNA damage in Caco-2 and Hep G2 cells

Flavonoids are reported to exhibit a wide variety of biological effects, including antioxidant and free radical-scavenging activities. Reactive oxygen species have been implicated in a range of human pathological diseases such as atherosclerosis and certain cancers. The aims of this present study were 1) to investigate the effect of the flavonoids myricetin, quercetin, and rutin on cell viability, endogenous antioxidant enzyme activities, and DNA integrity in Caco-2 and Hep G2 cells and 2) to determine whether these flavonoids could protect against H2O2-induced DNA damage. Both cell lines were supplemented with various concentrations (0-200 microM) of myricetin, quercetin, and rutin for 24 hours or H2O2 (50 microM) for 30 minutes, and cell viability was assessed. Over the concentration range tested, neither the flavonoids nor H2O2 significantly affected cell viability. The effect of the flavonoids on the activities of the antioxidant enzymes catalase (EC 1.11.1.6) and superoxide dismutase (EC 1.15.1.1) and on DNA integrity was assessed. The flavonoids did not significantly affect catalase or superoxide dismutase activity and did not induce DNA damage in either cell line. Exposure to 50 microM H2O2 for 30 minutes at 37 degrees C resulted in significant DNA damage, and preincubation with the flavonoids before H2O2 exposure significantly (p < 0.05) protected Caco-2 and Hep G2 cells against H2O2-induced DNA damage.

Organochlorine content of milks, dairy products and animal feed ingredients: Ireland 1971-1972

Milks (bovine and human) and dairy products (butter, cheese, skim and whey powders, calf-replacer, casein, butter-oil and dietetic food) were collected during 1971/2 throughout Ireland together with a more limited samples of the 10 major animal feed ingredients, and analysed for organochlorine insecticide residues using electron-capture gas chromatography. The different materials contained low or negligible levels of chlorinated insecticides. Apart from some of the animal feed ingredients the DDT residues were generally the predominant contaminants detected together with lower levels of gamma-BHC (lindane), aldrin/dieldrin and heptachlor/heptachlor epoxide. The maximum levels of these insecticides in the bovine milk and dairy products (511, 100, 62 and 21 mug/kg fat respectively) constitute only 50% or less of the Codex Tolerance Limits. The correspondingly low residue levels in the human milk (maxima of 128, 1, 1, and 5 mug/kg fat respectively) which at most represent insecticidal ingestion by infants equivalent to 13, 0-05, 5 and 5% respectively of the WHO/FAO acceptable daily intake for DDE, gamma-BHC, aldrin/dieldrin and heptachlor/heptachlor epoxide again pose no obvious health hazards and are strongly indicative of negligible organochlorine contamination in the general diet. The samples of animal feed ingredients examined also contained trace levels of ogranochlorines (maxima of 0-9, 0-1, 1-6 and 1-0 mug/kg respectively). More extensive monitoring of the residues in animal feed ingredients (the most probable source of milk contamination is advocated, and the desirability of tolerance limits for insecticides in animal feeds discussed.