TEAC Methods Research Articles

Increasing photostability and water-solubility of carotenoids: Synthesis and characterization of β-carotene–humic acid complexes

Carotenoids are a group of phytochemicals that are recognized as playing an important role in the prevention of several degenerative diseases due to their antioxidant activity. The low water-solubility and poor photostability of β-carotene, a potentially important dietary antioxidant, prompted us to investigate β-carotene complexes able to increase its water solubility as well as its photostability in aqueous solution. In this work we have used humic acid in order to synthesize β-carotene–humic acid complexes in different ratios. Complexes were characterized by FT-IR and DSC. β-Carotene determination were performed by HPLC and antioxidant activity of β-carotene, humic acid and the complexes were determined by the TEAC method. The formulation β-carotene–humic acid 2:1 showed the highest photostability and water solubility. The antioxidant activity of the complexes was about 20 times lower than “free” β-carotene, suggesting a decreased chemical reactivity of the carotenoid in the complex. We showed that complexation of β-carotene with humic acids was able to increase its water solubility and photostability, and to affect the antioxidant activity of β-carotene after inclusion in HAs. This work provides a useful tool to avoid antioxidants photodegradation and oxidation by radicals, thus maintaining their biological activity.

Facts about the formation of new antioxidants in natural samples after subcritical water extraction

Subcritical water extraction (SWE) is a very promising technique for obtaining bioactives (mainly antioxidants) from natural sources; even if sometimes the high operation temperatures have been suggested as responsible for thermal degradation of bioactives, the fact is that this type of extraction processes may generate new bioactive (antioxidant) compounds. The present study involved the analysis of antioxidants either naturally found in raw samples and/or those formed during extraction via Maillard reaction and other chemical events. Samples of different nature like microalgae ( Chlorella vulgaris), algae ( Sargassum vulgare, Porphyra spp., Cystoseira abies-marina, Sargassum muticum, Undaria pinnatifida, and Halopitys incurvus) and plants (rosemary, thyme and verbena) were studied. Amino acid availability, sugar content, fluorescence and absorbance at different wavelengths were determined to follow chemical changes due to reactions such as Maillard, caramelization and thermoxidation. Folin reaction also provided information related to total phenol content of the samples. ABTS +, peroxyl as well as superoxide radical scavenging assays were used to measure the antioxidant capacity of the extracts. Results obtained from this study suggest that neoformed compounds derived from Maillard, caramelization and thermoxidation reactions affect the overall antioxidant capacity of water subcritical extracts depending on the nature of the sample. The brown algae U. pinnatifida was the sample in which these chemical events contributed to a higher extent to improve the antioxidant capacity (from 0.047 to 1.512 mmol/g and from 45.356 to 1522.692 μmol/g for the TEAC and ORAC FL methods, respectively) when the extraction temperature was raised from 100 to 200 °C. To the best of our knowledge, this is the first work supporting the formation of neoantioxidants in natural complex matrices during subcritical water extraction.

PRELIMINARY INVESTIGATION ON ANTIOXIDANT FRUIT PROPERTIES OF SEVERAL APRICOT CULTIVARS UNDER ORGANIC AND INTEGRATED SYSTEMS IN METAPONTO AREA

The nutraceutical properties of fruits seem to be of particular interest to extend the 'fruit quality' concept, traditionally covered by the main pomological and physicochemical traits. The influence of the cultivation system on fruit quality is still poorly known and the aim of this research was to investigate the antioxidant properties of apricot fruit at harvest time and after cold storage, both under integrated and organic systems. Cultivars 'Tyrinthos', 'Cafona', 'Bella d'Italia' and 'Vitillo' were considered. The main pomological traits (weight, flesh firmness, total soluble sugars, tritable acidity) and antioxidant properties were analysed. In particular, the total antioxidant capacity (TEAC method) and phenols content (Folin-Ciocalteu method) were monitored. Apricot fruit is confirmed to be a good source of antioxidants, with variation on TAC and TP levels related to the cultivar rather than the cultivation system. Among the tested cultivars, 'Cafona' and 'Bella d'Italia' showed the highest total antioxidant capacity and phenol content. In all cultivars, the cold storage did not negatively affect the antioxidant properties of fruits.

Pomological and Nutraceutical Properties in Apricot Fruit: Cultivation Systems and Cold Storage Fruit Management

We have investigated the effect of cultivation systems and fruit post-harvest management on the antioxidant properties of apricot fruits. Trees of five cultivars 'Tyrinthos', 'Cafona', 'Bella d'Italia', 'Vitillo' and 'Pellecchiella' were cultivated under integrated and organic systems. Fruits were collected at full maturity stage and analyzed either immediately or after storage at 4+/-0.5 degrees C and 85% of relative humidity for seven and 14 days. The main pomological traits (weight, colour, flesh firmness, total soluble sugars, titratable acidity) and antioxidant properties were analyzed. The total antioxidant capacity (TAC by TEAC method), total phenols content (TP by Folin-Ciocalteu method) and carotenoid content by HPLC-DAD were monitored. Cultivar characterization by principal component analysis (PCA) indicated a large variability on pomological and antioxidant properties of apricot fruits. 'Bella d'Italia' showed better TAC and TP values compared to the other cultivars. ANOVA interactions between cultivar and cultivation system (organic/integrated) were found for the antioxidant properties. These interactions may help to select a set of genotypes with better performances under organic system, which in our study might be indicated in 'Cafona' and 'Bella d'Italia'.

New Tool To Evaluate a Comprehensive Antioxidant Activity in Food Extracts: Bleaching of 4-Nitroso-N,N-dimethylaniline Catalyzed by Soybean Lipoxygenase-1

In this study the 4-nitroso-N,N-dimethylaniline (RNO) bleaching associated with linoleic acid hydroperoxidation catalyzed by the soybean lipoxygenase (LOX)-1 isoenzyme (LOX/RNO reaction) was used to determine the antioxidant activity (AA) of hydrophilic and lipophilic pure antioxidant compounds and of mixtures of antioxidants extracted from durum wheat whole flour (DWWF). By means of a simple and rapid experimental protocol (about 3 min/assay), the LOX/RNO reaction may simultaneously detect many antioxidant functions (scavenging of some physiological radical species, iron ion reducing and chelating activities, inhibition of the pro-oxidant apoenzyme), thus providing a comprehensive AA evaluation. Consistently, the LOX/RNO assay was very sensitive to hydrophilic, lipophilic, and phenolic antioxidant extracts from DWWF, providing AA values at least 35 and 30 times higher than those by TEAC and ORAC methods, respectively. Moreover, the new method was able to highlight synergism (among extracts) 3 times more than the ORAC method, whereas TEAC did not measure synergism under our experimental conditions.

Identification and antioxidant activity of anthocyanins extracted from the seed and cob of purple corn (Zea mays L.)

The total anthocyanin content (TAC) and the antioxidant activity of the seed and cob from Chinese purple corn ( Zea mays L., cv Zihei) extracts were determined by pH-differential method, and DPPH, FRAP, and TEAC methods, respectively. TAC in purple corn cob anthocyanins (PCCAs) extract was higher than TAC in purple corn seed anthocyanins (PCSAs) extract. Compared to bulylated hydroxytoluene (BHT), PCCAs and PCSAs possessed significantly higher antioxidant activities, according to the DPPH, FRAP and TEAC assays. A satisfactory correlation between TAC and antioxidant activity was observed. Result indicated that cyanidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside were components in PCSAs extracts, and seven kinds of anthocyanin had been detected and six kinds of anthocyanin in PCCAs extracts were separated and identified them as cyanidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside, and their respective malonated counterparts as their anthocyanins using HPLC–MS analysis. In the last decades, in interest in anthocyanin pigments has increased because of their possible utilization as natural food colorants and especially as antioxidant and anti-inflammatory agents. Purple corn is a pigmented variety of Z. mays L., originally cultivated in Latin America. Now, this corn variety is mainly grown in China, especially in Shanxi and Anhui Province, could be new and interesting sources to obtain extracts rich in anthocyanins for their use in food, pharmaceutical and cosmetic industries. Our results indicated that the seed and cob of purple corn possessed excellent antioxidant activity, which could lead to increased application of these natural food colorants by the food industry.

Impact of Fruit Beverage Consumption on the Antioxidant Status in Healthy Women

Background: Epidemiologic studies suggest that antioxidant-rich foods might reduce the risk of cancer and cardiovascular diseases. Aim: To test the health-protective potential of three fruit beverages, Fb (grape-orange-apricot), FbM (Fb with skimmed milk) and FbMFe [FbM + Fe(II)], in healthy women. Methods: The influence of fruit beverage consumption (500 ml/day) upon serum antioxidant capacity determined by ORAC and TEAC methods and erythrocyte superoxide dismutase (SOD) activity was assessed in 32 healthy female volunteers. In the intervention study, each subject received the fruit beverages during three periods (3 weeks for Fb and FbM, and 12 weeks in the case of FbMFe), with a 2-week washout period between treatments. Results: Intake of fruit beverages does not improve total antioxidant capacity. However, the induction of SOD found after fruit beverage consumption may be more effective than the effects of antioxidants present in these beverages, which can only stoichiometrically scavenge reactive species derived from oxidative stress. Conclusion: Iron added to FbM (FbMFe) showed induction of SOD activity, with no prooxidant effect, and could constitute a complementary source of iron, because the regular consumption of FbMFe may be beneficial for women of fertile age.

Determination of polyphenolic content and antioxidant activity of kudingcha made from Ilex kudingcha C.J. Tseng

The total polyphenol content and the antioxidant activity of kudingcha made from Ilex kudingcha C.J. Tseng were determined by Folin–Ciocalteu reagent, and DPPH, FRAP, and TEAC methods, respectively. The crude extract (CE) of kudingcha and its four fractions of chloroform (CfF), ethyl acetate (EaF), n-butanol (nBF), and water (WtF) were prepared and subjected to antioxidant evaluation and analysis by high performance liquid chromatography. The extracts of kudingcha contained large amounts of caffeoylquinic acid (CQA) derivatives, including 3-CQA, 5-CQA, 3,4-diCQA, 3,5-diCQA, and 4,5-diCQA, and showed potent antioxidant activity. The antioxidant activities of CE and its fractions decreased in the order of EaF > nBF > CE > WtF > CfF, according to the DPPH assay and FRAP assay, which were the same, with the exception of the rank order of CfF and WtF, as the TEAC assay. Furthermore, a satisfactory correlation between total polyphenol content and antioxidant activity was observed.

Comparison of Spectrophotometric and Electrochemical Methods for the Evaluation of the Antioxidant Capacity of Buckwheat Products after Hydrothermal Treatment

This paper reports the use of spectrophotometric and voltammetric methods for the determination of the antioxidant capacity of buckwheat and its products originated from a technological line of a buckwheat roasted groats producer. 80% methanol extracts from raw and roasted buckwheat and groats and hulls obtained from roasted buckwheat were used. The spectrophotometric methods included (1) free radical scavenging activities of the extracts against ABTS*+ radical cation (TEAC) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH RSA) and (2) determination of reducing capacity by the means of Folin-Ciocalteu reagent (FCR) application. The radical scavenging activities of the extracts were also investigated using a voltammetric assay. Moreover, the flavonoids profiles of the studied materials were provided. Buckwheat roasting caused a decrease in TEAC, DPPH RSA, and FCR reducing capacity by 70%. The lowest TEAC, DPPH RSA, and FCR reducing capacities were noted for roasted groats. Both DPPH RSA and TEAC methods were highly positively correlated with the FCR reducing capacity assay (r = 0.98 and r = 0.99). Cyclic voltammograms of analyzed buckwheat extracts were useful for evaluation of the antioxidant capacity. The total charge below the anodic current waveform was correlated with the data obtained by TEAC (r = 0.770), DPPH RSA (r = 0.88), and FCR reducing capacity (r = 0.81). The changes in the antioxidant capacity of buckwheat and its products followed the changes in flavonoids composition. In particular, the concentration of flavonoids was related to measurements by cyclic voltammetry.

Flavonoid and polyphenol content of Aloe vera (Aloe barbadensis Mill.) flowers and their in vitro antioxidative capacity

Aloe vera has become very popular in cosmetics and nutraceutical formulations due to the ascribed beneficial properties of the inner gel from the fleshy leaves (Aloe vera gel). The big yellow flowers of A. barbadensis are not of commercial interest yet although the Aloe flowers were shown to contain various biologically active substances like e.g. phenolcarboxylic acids and flavonoids [1,2,3] and a few products, e.g. „Aloe flower herbal tea“, have appeared on the market. The aim of this study was to investigate the correlation of the polyphenol content and the antioxidative capacity. Therefore the polyphenols and their flavonoid portions of three batches of the years 2003, 2004, and 2005 were determined and the in vitro antioxidative capacity was measured. The polyphenol content was analysed with the Folin-Ciocalteu reagent (λ=760 nm, water extracts) and the flavonoid content with oxalic/boric acid (λ=410 nm, 60% ethanolic extracts). The antioxidative capacity was determined by the TEAC method [4] and the ORAC method [5].

Dietary fibre composition, antioxidant capacity and physico-chemical properties of a fibre-rich product from cocoa ( Theobroma cacao L.)

The proximate composition and dietary fibre (DF) content of a fibre-rich product obtained from cocoa were studied. This product contained 60.54% (dry matter basis) of DF, made of mainly insoluble fibre although with appreciable amounts of soluble dietary fibre (10.09% d.m.). The presence of associated polyphenolic compounds (1.32% and 4.46% of soluble polyphenols and condensed tannins, respectively) provides this fibre material with intrinsic antioxidant capacity as determined by the FRAP and TEAC methods. Hydration properties (swelling and water holding capacity) and the glucose retardation index of cocoa fibre were similar to other natural commercial insoluble fibres. The antioxidant capacity of this fibre-rich cocoa powder and its physico-chemical properties render it a suitable product to be used in the preparation of low-calorie, high-fibre foods.

Activity of paraoxonase 1 and lipid profile in healthy children

Paraoxonase 1 (PON1) seems to have a relevant role in detoxifying processes and in atherosclerosis. The aim of this study was to determine PON1 activity, the total antioxidant capacity, as well as entire lipid profile in children for screening of possible risk of atherosclerosis development. Serum PON1 arylesterase/paraoxonase activities were determined spectrophotometrically. The total antioxidant capacity of the serum was measured by TEAC method. Parameters of lipid profile were analyzed by routine laboratory methods. It has been shown that PON1 arylesterase/ paraoxonase activities were very similar to values found in adults. In children, no significant correlation between PON1 arylesterase activity and HDL was observed. PON1 paraoxonase activity correlated only with atherogenic index. PON1 arylesterase activity was significantly higher in girls than in boys. The antioxidant capacity was inversely related to the body mass index. In this study, PON1 activity was determined in healthy children aged 11 to 12 years and we found a similarity in PON1 activities of children and adults. Moreover, the results of our study support the hypothesis that higher body weight of children may contribute to a greater risk for development of atherosclerosis in which oxidative stress plays a role.

Antioxidant properties of Cortex Fraxini and its simple coumarins

We present the antioxidant properties of crude extract, fractions and ingredients of Cortex Fraxini (CF) and compare the antioxidant capacities of coumarin ingredients of CF and known antioxidants, including catechin, quercetin, ascorbic acid, trolox and BHT. The IC 50 values for CF in the DPPH and TEAC methods were 406 and 39.3 μg/ml, respectively. Among all fractions the chloroform fraction is the most active fraction in scavenging DPPH, ABTS and hydroxyl radicals, and there is a significant relationship between the antioxidant activities and the contents of the antioxidant phenolic ingredients. The contents of esculetin and fraxetin in the chloroform fraction were 8.44% and 11.1%, respectively. Esculetin and fraxetin also had good radical-scavenging capacities, and esculetin was the best, among all test compounds, against the DPPH radical. Moreover, esculetin and fraxetin had selective scavenging activity upon hydroxyl radicals and hydrogen peroxide, and this potency was better than known antioxidants and equal to quercetin in scavenging hydrogen peroxide. These results show that CF, partitioned with chloroform, gave a phenolic coumarin-enriched fraction, and that this fraction had the best free radical-scavenging activity and inhibition of Fe 2+/ascorbate-induced lipid peroxidation, mainly due to its reducing power.

Optimization of the Extraction of Antioxidants from Dunaliella salina Microalga by Pressurized Liquids

In this work, extraction of antioxidant compounds from Dunaliella salina microalga is optimized by combining pressurized liquid extraction (PLE) and experimental design (three-level factorial design) with three different solvents (hexane, ethanol, and water). Two main factors were considered, the extraction temperature (40, 100, and 160 degrees C) and the extraction time (5, 17.5, and 30 min). As response variables, the extraction yield (percent dry weight/initial weight) and the antioxidant activity of the extracts (determined using the TEAC method) were used. The parameters of the model were estimated by multiple linear regression. Results showed that the extraction temperature was the factor having the strongest influence (positive) on the two response variables. The best yields were obtained with ethanol at the higher extraction temperature and time tested. Besides, although hexane extracts provided the best antioxidant activity, ethanol extracts were also very active. The chemical characterization of ethanol extracts was carried out using HPLC-DAD, and attempts have been made to correlate their chemical composition with the antioxidant activity measured. Results pointed out that the extracts contained, besides all-trans-beta-carotene and isomers, several different minor carotenoids that seemed to make a contribution to the antioxidant activity of the extracts.

Assessment of the TEAC method for determining the antioxidant capacity of synthetic red food colorants

The TEAC method was used to evaluate the antioxidant capacity of six synthetic red food colorants (azorubine, amaranth, ponceau 4R, erythrosine, red 2G and allura red AC). This method assesses the ability of such compounds to scavenge the stable radical cation chromophore ABTS + , comparing it with that of Trolox, a water soluble vitamin E analogue. It is simple, fast (6 min) and, at the wavelength used for measurements (735 nm) does not interfere with the absorption maxima of the colorants. The experiments showed an antioxidant ranking of allura red AC > azorubine > amaranth > red 2G > erythrosine > ponceau 4R. Their corresponding TEAC values were 0.029, 0.026, 0.019, 0.018, 0.016 and 0.007, respectively.

Investigations on the antioxidant activity of fruit and vegetable aqueous extracts on superoxide radical anion using chemiluminescence techniques

A sensitive and simple method for measuring antioxidant activity was developed, based on antioxidant-dependant quenching of the chemiluminescence (CL) generated from 9-benzylacridine and potassium superoxide. This method was used to evaluate the antioxidant activity of fruit and vegetable aqueous extracts as well as of some pure phenolic compounds contained in fruits and vegetables. Coumaric, chlorogenic, caffeic, vanillic and ascorbic acids as well as (±)catechin, and 2-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox) were employed as antioxidants. It was found that the antioxidant activity of all fruit extracts is almost one order of magnitude higher than that of vegetables. Among the fruits, grapefruits show the highest antioxidant activity and pears the lowest. From the pure phenolic antioxidants, caffeic acid has the highest antioxidant activity (AA). The calculated antioxidant activities of fruit and vegetable extracts produced by the CL method are compared with other methods such as the ORAC, TEAC or DPPH method.