Content and profile of flavanoid and phenolic acid compounds in conjunction with the antioxidant capacity for a variety of northwest Vaccinium berries

This investigation evaluated the content and profile of flavanoid and phenolic acid compounds present in nine Vaccinium species that included domestic blueberry cultivars and sample collections from undomesticated colonies. The study was focused in two areas of inquiry. The first involved extracting and analyzing the berries for total phenolics (TPH), total anthocyanins (ACY), and the antioxidant capacity. Vaccinium species differ in their polyphenolic content, and these high TPH and ACY levels are correlated to their antioxidant capacity. Second, berry extracts were analyzed by high-performance liquid chromatography equipped with photodiode array and mass spectrometric detectors to determine the content and profile of selected bioactive compounds. The flavanoid analytes of interest included the anthocyanidins, flavan-3-ols, and flavonol aglycons, as well as specific phenolic acid components. This semicomprehensive analysis begins to characterize the phytochemical profiles and illustrates the differences in the content of polyphenolic compounds present within these Vaccinium species.     

Bioactive compounds, myrosinase activity, and antioxidant capacity of white cabbages grown in different locations of Spain

The influence of two Spanish growing locations with well-differentiated climatic conditions (northern and eastern areas) on the main bioactive compounds, glucosinolates (GLS), total phenolic compounds (TPC), and vitamin C, as well as myrosinase activity and antioxidant capacity in five white cabbage ( Brassica oleracea L. var. capitata) cultivars was investigated. Cabbages with the highest concentration of total GLS presented the highest vitamin C level (r = 0.75, P ≤ 0.05) and the lowest antioxidant capacity (r = -0.76, P ≤ 0.05). The cultivars with the highest vitamin C content had the lowest myrosinase activity (r = -0.89, P ≤ 0.05) and antioxidant capacity (r = -0.86, P ≤ 0.05), whereas those with the largest TPC amount showed the highest antioxidant capacity (r = 0.71, P ≤ 0.05). Cabbage cultivars grown in the northern area of Spain with low temperatures and radiation led to higher mean values of myrosinase activity (29.25 U/g dm), TPC (10.0 GAE mg/g dm), and antioxidant capacity (81.6 μmol Trolox/g dm), whereas cultivars grown in the eastern area with high temperature and radiation led to larger mean values of GLS (14.3 μmol/g dm) and vitamin C (5.3 mg/g dm). The results of this investigation provide information regarding the most suitable Spanish growing location to produce white cabbage with an optimized content of health-promoting compounds.     

Major flavonoids in grape seeds and skins: antioxidant capacity of catechin, epicatechin, and gallic acid

Grape seeds and skins are good sources of phytochemicals such as gallic acid, catechin, and epicatechin and are suitable raw materials for the production of antioxidative dietary supplements. The differences in levels of the major monomeric flavanols and phenolic acids in seeds and skins from grapes of Vitis vinifera varieties Merlot and Chardonnay and in seeds from grapes of Vitis rotundifolia variety Muscadine were determined, and the antioxidant activities of these components were assessed. The contribution of the major monomeric flavonols and phenolic acid to the total antioxidant capacity of grape seeds and skins was also determined. Gallic acid, monomeric catechin, and epicatechin concentrations were 99, 12, and 96 mg/100 g of dry matter (dm) in Muscadine seeds, 15, 358, and 421 mg/100 g of dm in Chardonnay seeds, and 10, 127, and 115 mg/100 g of dm in Merlot seeds, respectively. Concentrations of these three compounds were lower in winery byproduct grape skins than in seeds. These three major phenolic constituents of grape seeds contributed <26% to the antioxidant capacity measured as ORAC on the basis of the corrected concentrations of gallic acid, catechin, and epicatechin in grape byproducts. Peroxyl radical scavenging activities of phenolics present in grape seeds or skins in decreasing order were resveratrol > catechin > epicatechin = gallocatechin > gallic acid = ellagic acid. The results indicated that dimeric, trimeric, oligomeric, or polymeric procyanidins account for most of the superior antioxidant capacity of grape seeds.     

Antioxidants, low molecular weight carbohydrates, and total antioxidant capacity in strawberries (Fragaria x ananassa): effects of cultivar, ripening, and storage

Four cultivars of strawberries (Senga Sengana, BFr77111, Elsanta, and Honeoye) were studied for their content of antioxidants, total antioxidant capacity, and low molecular weight carbohydrates in relation to harvest year, ripening stage, and cold storage. For ascorbic acid, chlorogenic acid, ellagic acid, and total antioxidative capacity, measured in both water-soluble and water-insoluble extracts, there was a 2-5-fold variation among cultivars. Unripe berries contained lower concentrations of chlorogenic acid and p-coumaric acid and also quercetin and kaempferol compared with riper berries. During cold storage for up to 3 days, relatively few changes in the concentration of the different antioxidants occurred. The concentrations of several investigated parameters were interrelated, for example, for ascorbic acid and water-soluble antioxidant capacity and for ellagic acid and water-insoluble antioxidant capacity. The dominating sugars in strawberries were fructose and glucose, but considerable amounts of sucrose were also present, and their contents varied among cultivars, giving a predicted glycemic index of approximately 81. Verbascose, raffinose, and stachyose were found in only minor amounts. The study shows that the concentration of a number of bioactive compounds in strawberries varied according to cultivar, ripening stage, and storage. This information should make it possible to select strawberries with an optimal content of bioactive compounds.     

Effect of ascorbic acid and dehydration on concentrations of total phenolics, antioxidant capacity, anthocyanins, and color in fruits

The purpose of this investigation was to report on the total phenolics, anthocyanins, and oxygen radical absorbance capacity (ORAC) of strawberry, peach, and apple, the influence of dehydration and ascorbic acid treatments on the levels of these compounds, and the effect of these treatments on fruit color. Results showed that fresh strawberry had the highest levels for total phenolics [5317.9 mg of chlorogenic acid equivalents (CAE)/kg], whereas lower levels were found in fresh apple and peach (3392.1 and 1973.1 mg of CAE/kg, respectively), and for anthocyanins (138.8 mg/kg), whereas lower levels were found in fresh apple and peaches (11.0 and 18.9 mg/kg, respectively; fresh strawberry had an ORAC value of 62.9 mM/kg Trolox equivalents. The fresh apple and peach were found to have ORAC values of 14.7 and 11.4 mM/kg of Trolox equivalents, respectively. The color values indicated that the addition of 0.1% ascorbic acid increased the lightness (L) and decreased the redness (a) and yellowness (b) color values of fresh strawberry, peach, and apple, sliced samples, and the puree made from them. Also, results showed that dehydration is a good method to keep the concentrations of total phenolics and anthocyanins and ORAC values at high levels.     

Impact of high pressure and pulsed electric fields on bioactive compounds and antioxidant activity of orange juice in comparison with traditional thermal processing

Bioactive compounds (vitamin C, carotenoids, and flavanones) and DPPH* radical scavenging capacity (RSC) were measured in orange juice (OJ) subjected to different technologies. High pressure (HP) (400 MPa/40 degrees C/1 min), pulsed electric fields (PEF) (35 kVcm(-1)/750 micros), low pasteurization (LPT) (70 degrees C/30 s), high pasteurization (HPT) (90 degrees C/1 min), HPT plus freezing (HPT+F) (-38 degrees C/15 min), and freezing (F) were studied. Among the treatments assayed, even though the losses in total vitamin C were < 9%, treatments with the higher temperatures tended to show the higher decrease in the content of both forms of vitamin C. HP treatment led to an increased (P < 0.05) carotenoid release (53.88%) and vitamin A value (38.74%). PEF treatment did not modify individual or total carotenoids content. Traditional thermal treatments did not exert any effect on total carotenoid content or vitamin A value. With regard to individual carotenoid extraction, HPT and HPT+F led to different releases of carotenoids. With respect to flavanones, HP treatment led to increased (P < 0.05) naringenin (20.16%) and hesperetin (39.88%) contents, whereas PEF treatment did not modify flavanone content. In general, pasteurization and freezing process led to a diminished (P < 0.05) naringenin content (16.04%), with no modification in hesperetin. HP and PEF treatments did not modify DPPH* RSC. In the case of traditional thermal technologies, HPT treatment showed a decrease (P < 0.05) in RSC (6.56%), whereas LPT, HPT+F, and F treatments did not modify RSC. Vitamin C modulated RSC, in terms of antioxidant concentration (EC50) and kinetics (AE = 1/EC50TEC50), in the treated and untreated OJ. In summary, HP and PEF technologies were more effective than HPT treatment in preserving bioactive compounds and RSC of freshly squeezed orange juice.     

Total phenolic content, antioxidant activity, and cross-cultural consumer rejection threshold in white and red wines functionally enhanced with catechin-rich extracts

White and red wines spiked with catechin-rich green tea extract and grape seed extract were assessed for phenolic content, antioxidant activity, and cross-cultural consumer rejection thresholds in relation to wine as a functional food. Health functionality is an important factor in functional foods, and spiking pure compounds or plant extracts is an effective method to increase or control functionality. The total phenolic content and antioxidant activity were measured in wines spiked to different extract concentrations, namely, control and 50, 100, 200, 400, and 800 mg/L, to confirm the dose-response curves in both white and red wines. Consumer rejection thresholds (CRTs) were established for spiked wines in a Korean and in an Australian population. Our results showed that the green tea extract and grape seed extract increased the antioxidant activity dose dependently, and the CRTs varied considerably between the Korean and the Australian groups, with Koreans preferring wines spiked with green tea extract and Australians showing a preference for wines spiked with grape seed extract. These results have implications for producing wine products that are enhanced in phenolic compounds and targeted to different cultural groups.     

Formation of volatile compounds in model experiments with crude leek (Allium ampeloprasum Var. Lancelot) enzyme extract and linoleic acid or linolenic acid

Three continuous assays are described for lipoxygenase (LOX), hydroperoxide lyase (HPL) and alcohol dehydrogenase (ADH) in leek tissue. The catalytic activity of LOX showed significant difference (significance level 5%) between linolenic acid (9.43 x 10(-)(4) katals per kg protein) and linoleic acid (2.53 x 10(-)(4) katals per kg protein), and the pH-optimum of LOX was 4.5-5.5 against linoleic acid. The catalytic activity of HPL was statistically the same for 9-(S)-hydroperoxy-(10E,12Z)-octadecadienoic acid (1.01 x 10(-)(2) katals per kg protein) and 13-(S)-hydroperoxy-(9Z,11E)-octadecadienoic acid (7.69 x 10(-)(3) katals per kg protein). ADH showed a catalytic activity of 5.01 x 10(-)(4) katals/kg of protein toward hexanal. Model experiments with crude enzyme extract from leek mixed with linoleic acid or linolenic acid demonstrated differences in the amount of produced aroma compounds. Linoleic acid resulted in significantly most hexanal, heptanal, (E)-2-heptenal, (E)-2-octenal, (E,E)-2,4-decadienal, pentanol, and hexanol, whereas linolenic acid resulted in significantly most (E)-2-pentenal, (E)-2-hexenal, (E,Z)-2,4-heptadienal, (E,E)-2,4-heptadienal, and butanol. Leek LOX produced only the 13-hydroperoxide of linoleic acid and linolenic acid.     

Differential regulation of calmodulin,phenylalanine ammonia-lyase,and salicylic acid in response to Botrytis cinerea infection in tomato with different Ca2+ concentrations

To investigate the responses to Botrytis cinerea (B. cinerea) infection and the effects of exogenous Ca²⁺ on calmodulin (CaM), phenylalanine ammonia-lyase (PAL), and salicylic acid (SA) biosynthesis and concentrations, we investigated the role of exogenous calcium in defense and resistance to the necrotrophic fungus B. cinerea in tomato (Lycopersicon esculentum Mill.). Specifically, 7.5 mM Ca²⁺ was the best treatment for plant resistance, resulting in stable and permanent resistance to the pathogen. This treatment improved plant resistance and the results also confirmed that the concentrations of CaM and SA are negatively correlated with the resistance response.     

Polyphenolic compounds, antioxidant capacity, and quinone reductase activity of an aqueous extract of Ardisia compressa in comparison to mate (Ilex paraguariensis) and green (Camellia sinensis) teas

Aqueous extracts of the leaves of Ardisia compressa (AC) have been used in folk medicine to treat various liver disorders including liver cancer. The objective of this study was to partially characterize and determine the total polyphenol content, antioxidant capacity, and quinone reductase activity of A. compressa tea in comparison to mate (Ilex paraguariensis, MT) and green (Camellia sinensis,GT) teas. Total polyphenol content, antioxidant capacity, and phase II enzyme induction capacity were measured by the modified Folin-Ciocalteu, ORAC, and quinone reductase (QR) assays, respectively. The major polyphenols in AC were not catechins. HPLC retention times and standard spikes of AC indicated the presence of gallic acid, epicatechin gallate, ardisin and kaempferol. Using catechin as standard, the total polyphenol value of AC (36.8 +/- 1.1 mg/mg DL) was significantly lower than GT (137.2 +/- 5.8 mg equivalent of (+)-catechin/mg dried leaves, DL) and MT (82.1 +/- 3.8 mg/mg DL) (P < 0.001). Antioxidant capacity (AC, 333; GT, 1346; MT, 1239 mmol Trolox equivalents/g DL) correlated with total polyphenol values (r(2) = 0.86, P < 0.01). AC (4.5-12.5 microg/mL) induced QR enzyme, in Hepa1c1c7 cells, up to 15%. MT and GT showed no induction at the concentrations tested (0.5-10.5 and 0.5-12.5 mg/mL, respectively). These results suggest that AC has a different mechanism of protection against cytotoxicity that is not related to its antioxidant capacity. Further studies are needed to determine such mechanisms and to explore its potential as a chemopreventive or therapeutic agent.     

Content of polyphenolic compounds in the Nigerian stimulants Cola nitida ssp. alba, Cola nitida ssp. rubra A. Chev, and Cola acuminata Schott & Endl and their antioxidant capacity

Varieties of kola nuts (Cola nitida alba, Cola nitida rubra A. Chev, and Cola acuminata Schott & Endl), a group of popular Nigerian and West African stimulants, were analyzed for their content of secondary plant metabolites. The three varieties of the kola nuts contained appreciable levels of (+)-catechin (27-37 g/kg), caffeine (18-24 g/kg), (-)-epicatechin (20-21 g/kg), procyanidin B 1 [epicatechin-(4beta-->8)-catechin] (15-19 g/kg), and procyanidin B2 [epicatechin-(4beta-->8)-epicatechin] (7-10 g/kg). Antioxidant capacity of the extracts and purified metabolites was assessed by two HPLC-based and two colorimetric in vitro assays. Extracts of all varieties exhibited antioxidant capacity with IC 50 values in the range 1.70-2.83 and 2.74-4.08 mg/mL in the hypoxanthine/xanthine oxidase and 2-deoxyguanosine HPLC-based assays, respectively. Utilization of HPLC-based assays designed to reflect in situ generation of free radicals (e.g., HO(*)), as opposed to general assays (DPPH, FRAP) in common use which do not, indicate that, of the major secondary plant metabolites present in kola nut extracts, caffeine is potentially the more effective cancer chemopreventive metabolite in terms of its antioxidant capacity.     

Identification and quantitation of key aroma compounds formed in Maillard-type reactions of fructose with cysteamine or isothiaproline (1,3-thiazolidine-2-carboxylic acid)

Fructose was reacted in the presence of either cysteamine (model A) or isothiaproline (model B) in aqueous buffer at 145 degrees C and pH 7.0. Application of an aroma extract dilution analysis on the bulk of the volatile compounds formed in model A revealed 5-acetyl-3,4-dihydro-2H-1,4-thiazine (19), N-(2-mercaptoethyl)-1,3-thiazolidine (16), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (15), and 2-acetyl-2-thiazoline (11) as the key aroma compounds among the 10 odorants detected. A similar set of aroma compounds was formed when isothiaproline was reacted (model B), but the flavor dilution factors were generally lower. Substitution of the buffer by silica gel/water (9 + 1 w/w) in both models and application of 150 degrees C for 10 min also gave the same key odorants from both thio compounds; however, under these conditions isothiaproline was the better precursor of, in particular, 19 and 11. Quantitative measurements performed by means of stable isotope dilution assays revealed a significant effect of the pH on odorant formation. For example, in model A, formation of 19 as well as of 11 was suppressed at pH values <5.0. A clear maximum was, however, found for 19 at pH 7.0 (approximately 1 mol % yield), whereas 11 increased with increasing pH from 7.0 to 9.0.     

Cadmium‐ and barium‐toxicity effects on growth and antioxidant capacity of soybean (Glycine max L.) plants,grown in two soil types with different physicochemical properties

The pollution of agricultural soils by metals is of growing concern worldwide, and is increasingly subject to regulatory limits. However, the effect of metal pollutants on the responses of plants can vary with soil types. In this study, we examined the growth and antioxidant responses of soybean plants exposed to contrasting soils (Oxisol and Entisol), which were artificially contaminated with cadmium (Cd) or barium (Ba). Cadmium reduced plant growth at concentrations higher than 5.2 mg (kg soil)^–1, while Ba only affected plant growth at 600 mg kg^–1. Such levels are higher than the limits imposed by the Brazilian environmental legislation. Lipid peroxidation was increased only at a Cd concentration of 10.4 mg kg^–1 in the Oxisol, after 30 d of exposure. Twelve superoxide dismutase (SOD; EC 1.15.1.1) isoenzymes were evaluated, most of which were classified as Cu/Zn forms. The SOD activity in the leaves of plants grown in the Oxisol decreased over time, whilst remaining high in the Entisol. Catalase (CAT; EC 1.11.1.6) activity in the leaves exhibited little response to Cd or Ba, but increased over time. Glutathione reductase (GR; EC 1.6.4.2) activity was reduced over time when exposed to the higher Cd concentrations, but increased following Ba exposure in the Oxisol. The enzyme‐activity changes were mainly dependent on soil type, time of exposure and, to a lesser extent, the metal concentration of the soil. Soybean plants grown in a sandy soil with a low buffering capacity, such as Entisol, suffer greater oxidative stress than those grown in a clay soil, such as Oxisol.     

Effects of glucose and rhizodeposits (with or without cysteine-S) on immobilized-35S, microbial biomass-35S and arylsulphatase activity in a calcareous and an acid brown soil

Our aim was to study the effects of C (as glucose and artificial rhizodeposits) on S immobilization, in relation to microbial biomass‐S and soil arylsulphatase (ARS) activity, in contrasting soils (a calcareous and an acid brown soil). The glucose‐C and artificial rhizodeposit‐C with or without cysteine were added at six rates (0, 100, 200, 400, 600 and 800 mg kg^?1 soil) to the two soils and then incubated with Na₂³⁵SO₄ for 1 week prior to analysis. The percentages of ³⁵S immobilized increased when C as glucose and rhizodeposit (without cysteine) were added to both soils. With cysteine‐containing rhizodeposit, the percentages of ³⁵S immobilized remained relatively stable (23.5% to 29.9%) in the calcareous soil, but decreased in the acid brown soil (52.7% to 31.5%). For both soils, cysteine‐containing rhizodeposit additions showed no significant correlation between immobilized‐³⁵S and microbial biomass‐³⁵S, suggesting that microorganisms immobilized cysteine‐S preferentially instead of ³⁵S from the tracer (Na₂³⁵SO₄). In the calcareous soil, a positive and significant correlation was found between ARS activity and microbial biomass‐³⁵S (r = 0.85, P < 0.05) when glucose was added. We also saw this correlation in the acid brown soil when rhizodeposit‐C without cysteine was added (r = 0.90, P < 0.05). Accordingly, the results showed the presence of extracellular arylsulphatase activity of 48.7 mg p‐nitrophenol kg^?1 soil hour^?1 in the calcareous soil and of 27.0 mg p‐nitrophenol kg^?1 soil hour^?1 in the acid brown soil.