An investigation of antioxidant capacity of fruits in Singapore markets

Total antioxidant capacity of plant foods, beverages and oils consumed in Italy assessed by three different in vitro assays

Epidemiologic studies have demonstrated an inverse association between consumption of fruits and vegetables and morbidity and mortality from degenerative diseases. The antioxidant content of fruits and vegetables may contribute to the protection they offer from disease. Because plant foods contain many different classes and types of antioxidants, knowledge of their total antioxidant capacity (TAC), which is the cumulative capacity of food components to scavenge free radicals, would be useful for epidemiologic purposes. To accomplish this, a variety of foods commonly consumed in Italy, including 34 vegetables, 30 fruits, 34 beverages and 6 vegetable oils, were analyzed using three different assays, i.e., Trolox equivalent antioxidant capacity (TEAC), total radical-trapping antioxidant parameter (TRAP) and ferric reducing-antioxidant power (FRAP). These assays, based on different chemical mechanisms, were selected to take into account the wide variety and range of action of antioxidant compounds present in actual foods. Among vegetables, spinach had the highest antioxidant capacity in the TEAC and FRAP assays followed by peppers, whereas asparagus had the greatest antioxidant capacity in the TRAP assay. Among fruits, the highest antioxidant activities were found in berries (i.e., blackberry, redcurrant and raspberry) regardless of the assay used. Among beverages, coffee had the greatest TAC, regardless of the method of preparation or analysis, followed by citrus juices, which exhibited the highest value among soft beverages. Finally, of the oils, soybean oil had the highest antioxidant capacity, followed by extra virgin olive oil, whereas peanut oil was less effective. Such data, coupled with an appropriate questionnaire to estimate antioxidant intake, will allow the investigation of the relation between dietary antioxidants and oxidative stress-induced diseases.

Bioactive novel polyphenols from the fruit of Manilkara zapota (Sapodilla)

Activity-guided fractionation of a methanol extract from the fruit of Manilkara zapota cv. Tikal resulted in the isolation of two new antioxidants, methyl 4-O-galloylchlorogenate (1) and 4-O-galloylchlorogenic acid (2), along with eight known polyphenolic antioxidants, namely, methyl chlorogenate (3), dihydromyricetin (4), quercitrin (5), myricitrin (6), (+)-catechin (7), (-)-epicatechin (8), (+)-gallocatechin (9), and gallic acid (10). Of the 10 polyphenols, 1 showed the highest antioxidant activity (IC(50) = 12.9 microM) in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assay and displayed cytotoxicity in the HCT-116 and SW-480 human colon cancer cell lines with IC(50) values of 190 and 160 microM, respectively. Compound 2 showed high antioxidant activity (IC(50) = 23.5 microM) in the DPPH free-radical assay and displayed cytotoxicity in the HCT-116 and SW-480 human colon cancer cell lines with IC(50) values of 154 and 134 microM, respectively.

Intake of fruits, vegetables and selected micronutrients in relation to the risk of breast cancer

High fruit and vegetable intake has been linked with a reduced risk of breast cancer, but evidence is not consistent. We investigated the associations of breast cancer risk with vegetables, fruits and related micronutrient intake in a population-based case-control study among Chinese women in Shanghai, where dietary patterns differ substantially from other study populations. Included in the study were 1,459 incident breast cancer cases and 1,556 frequency-matched controls. Usual dietary habits were assessed by in-person interviews. Logistic regression was used to compute adjusted odds ratios (ORs) and 95% confidence intervals (CIs) to measure strength of the associations. There was no association between breast cancer risk and total vegetable intake. The risk of breast cancer declined, however, with increasing intake of dark yellow-orange vegetables (trend test, p = 0.02), Chinese white turnips (trend test, p </= 0.001), and certain dark green vegetables (trend test, p </= 0.001) with adjusted OR in the highest quintile being 0.79 (95% CI = 0.60-0.98), 0.67 (95% CI = 0.53-0.85) and 0.65 (95% CI = 0.51-0.83) respectively. Intake of fruits, except watermelons and apples, was inversely associated with breast cancer risk (p-values for trend tests </=0.05). Our study suggests that high intake of certain vegetables and fruits may be associated with a reduced risk of breast cancer.

From plums to prunes: influence of drying parameters on polyphenols and antioxidant activity

Prunes, which are industrially obtained by dehydrating fresh plums at 85-90 degrees C for 18 h, contain higher levels of phenolic compounds than most other fruits. Prune phenolics have shown beneficial effects on human health. Reports are available in the literature on ascorbic acid, phenol composition, and antioxidant activity of fresh plums and prunes, but there is a lack of publications on the influence of drying parameters on the phenolic compounds and antioxidant activity. A study was carried out on two plum cultivars using two sets of air-drying temperatures: (i) air temperature at 85 degrees C until 50% of prune moisture level and then the temperature was lowered to 70 degrees C; (ii) air temperature at 60 degrees C. Whole fresh and dried fruits were assessed for phenolics (catechins, hydroxycinnamic acids, anthocyanins, and flavonols), ascorbic acid, and antioxidant activity (all parameters were calculated on a dry matter basis). Analysis of data shows that chlorogenic and neochlorogenic acid changes were affected by both process parameters and cultivar. Drying destroyed anthocyanins, and there was a significant decrease in flavonols. Ascorbic acid was drastically reduced in relation to process temperature. The most striking result was that drying at 85 degrees C doubled antioxidant activity in both cultivars, while contradictory results were found for 60 degrees C processed plums.

Stoichiometric and kinetic studies of phenolic antioxidants from Andean purple corn and red-fleshed sweetpotato

Stoichiometric and kinetic values of phenolics against DPPH (2,2-diphenyl-1-picrylhydrazyl) were determined for Andean purple corn (Zea mays L.) and red sweetpotato (Ipomoea batatas). Both crops had higher antioxidant capacity and antiradical kinetics than blueberries and higher or similar anthocyanin and phenolic contents. The second-order rate constant (k(2)) was 1.56, 1.12, 0.57, and 0.26 (mg antiradical/mL)(-1) s(-1) for red sweetpotato, Trolox, purple corn, and blueberry, respectively. On the molar basis of active hydroxyl groups, k(2)' showed the same order as for k(2). Corn cob and sweetpotato endodermis contributed the most in phenolic compounds and antioxidant capacity. Both crops studied can be considered as excellent novel sources of natural antioxidants for the functional food and dietary supplement markets.