Antioxidant Activity of Brazilian Vegetables and Its Relation with Phenolic Composition

Vegetables are widely consumed in Brazil and exported to several countries. This study was performed to evaluate the phenolic content and antioxidant activity of vegetables commonly consumed in Brazil using five different methods, namely DPPH and ABTS free radical, beta-carotene bleaching, reduction of Fe3+ (FRAP), oxidative stability in Rancimat, and the chemical composition using gas chromatography-mass spectrometry (GC-MS). The content of phenolic compounds ranged from 1.2 mg GA/g (carrot) to 16.9 mg GA/g (lettuce). Vegetables presenting the highest antioxidant activity were lettuce (77.2 mu mol Trolox/g DPPH center dot; 447.1 mu mol F2+/g FRAP), turmeric (118.6 mu mol Trolox/g ABTS(center dot+); 92.8% beta-carotene), watercress and broccoli (protective factor 1.29-Rancimat method). Artichoke, spinach, broccoli, and asparagus also showed considerable antioxidant activity. The most frequent phenolic compounds identified by GC-MS were ferulic, caffeic, p-coumaric, 2-dihydroxybenzoic, 2,5-dihydroxybenzoic acids, and quercetin. We observed antioxidant activity in several vegetables and our results point out their importance in the diet.

Antioxidant, anti-acetylcholinesterase and cytotoxic activities of ethanol extracts of peel, pulp and seeds of exotic Brazilian fruits Antioxidant, anti-acetylcholinesterase and cytotoxic activities in fruits

Ethanol extracts of powdered genipap (Genipa americana L), umbu (Spondia tuberosa A.) and siriguela (Spondia purpurea L) prepared from separate pulp, seeds and peel were investigated for their (i) antioxidant capacity, which was evaluated by various known methods; (ii) acetylcholinesterase (AChE) inhibitory activity; and (iii) cytotoxic effect on corneal epithelial cells of sheep. The highest values of total phenolic content were obtained with peel and seed extracts. Siriguela and umbu (seeds and peel) extracts displayed the highest antioxidant activities. Lipid peroxidation assays using mimetic biomembranes and mouse liver homogenates indicated that genipap pulp is a promising antioxidant. The investigation of phenols and organic acid contents revealed the presence of quercetin, citric and quinic acids, chlorogenic acid derivatives, among others, in several extracts, with the highest amount found in siriguela seeds. Genipap pulp and siriguela seed ethanol extracts presented an AChE inhibition zone similar to that of the positive control, carbachol. AChE inhibition assay with chlorogenic acid, one of the main constituents of siriguela seeds, revealed that this acid showed activity similar to that of the control physostigmine. These data suggest that these extracts are potentially important antioxidant supplements for the everyday human diet, pharmaceutical and cosmetic industries. (C) 2012 Elsevier Ltd. All rights reserved.

In vivo and in vitro antioxidant activity and hepatoprotective properties of polyphenols from Halimeda opuntia (Linnaeus) Lamouroux

Antioxidant activity and hepatoprotective properties of the aqueous extract and tetrahydrofuran-extracted phenolic fractions of Halimeda opuntia (Linnaeus) Lamouroux were investigated in rats with chemically induced liver injury. Total polyphenols were determined by using the Folin-Ciocalteau reagent. Liver damage was induced by CCl4 and assessed by a histological technique. Reverse transcription/polymerase chain reaction (RT/PCR) analysis showed increased superoxide dismutase (SOD) and catalase (CAT) gene expression and activities in the group treated with free phenolic acid (FPA) fractions of H. opuntia, suggesting inducing effects on both enzymes. In addition, rats treated with FPA fractions displayed lower liver thiobarbituric acid reactive substance (TBARS) levels than those observed for rats in the CCl4-treated group. These data suggest that the phenolic fractions from H. opuntia may protect the liver against oxidative stress-inducing effects of chemicals by modulating its antioxidant enzymes and oxidative status.

Increased Antioxidant Content in Juice Enriched with Dried Extract of Pomegranate (Punica granatum) Peel

Antioxidants are compounds responsible for free radical scavenging in the body. They protect the organism from oxidative modification of cells and tissues. These modifications have been associated with degenerative diseases, atherosclerosis and carcinogenesis. Punica granatum displays high antioxidant potential due to the presence of phenolic compounds, which are capable of disease prevention. The present study showed the highest antioxidant activity in pomegranate peel than in seeds and pulp. Based on these results, pomegranate peel was used to produce dried extract that was added to commercial tomato juice and orange juice with strawberries. Analysis to determine the content of phenolic compounds and antioxidant activity was performed on pomegranate pulp, seeds and peel and in juices enriched with dried extract of pomegranate peel. The dried extract was responsible for a significant increase in antioxidant activity of the juices, proportional to the concentrations added. However, although both flavors of enriched juices displayed high antioxidant levels, the samples with higher dried extract concentrations received the lowest scores from sensory analysis participants due to the characteristic astringent flavor of pomegranate peels. Therefore, to obtain greater acceptance in the consumer market, we concluded that the maximum addition of dried pomegranate peel extract is 0.5% in tomato juice and orange juice with strawberries.

Antioxidant treatment protects against matrix metalloproteinase activation and cardiomyocyte injury during acute pulmonary thromboembolism

Increased reactive oxygen species (ROS) promote matrix metalloproteinase (MMP) activities and may underlie cardiomyocyte injury and the degradation of cardiac troponin I (cTI) during acute pulmonary thromboembolism (APT). We examined whether pretreatment or therapy with tempol (a ROS scavenger) prevents MMP activation and cardiomyocyte injury of APT. Anesthetized sheep received tempol infusion (1.0 mg kg(-1) min(-1), i.v.) or saline starting 30 min before or 30 min after APT (autologous blood clots). Control animals received saline. Hemodynamic measurements were performed. MMPs were studied in the right ventricle (RV) by gelatin zymography, fluorimetric activity assay, and in situ zymography. The ROS levels were determined in the RV and cTI were measured in serum samples. APT increased the pulmonary arterial pressure and pulmonary vascular resistance by 146 and 164 %, respectively. Pretreatment or therapy with tempol attenuated these increases. While APT increased RV + dP/dt (max), tempol infusions had no effects. APT increased RV MMP-9 (but not MMP-2) levels. In line with these findings, APT increased RV MMP activities, and this finding was confirmed by in situ zymography. APT increased the RV ROS levels and tempol infusion, before or after APT, and blunted APT-induced increases in MMP-9 levels, MMP activities, in situ MMP activities, and ROS levels in the RV. cTI concentrations increased after APT, and tempol attenuated these increases. RV oxidative stress after APT increases the RV MMP activities, leading to the degradation of sarcomeric proteins, including cTI. Antioxidant treatment may prevent MMP activation and protect against cardiomyocyte injury after APT.

Short-term creatine supplementation decreases reactive oxygen species content with no changes in expression and activity of antioxidant enzymes in skeletal muscle

The effect of short-term creatine (Cr) supplementation upon content of skeletal muscle-derived-reactive oxygen species (ROS) was investigated. Wistar rats were supplemented with Cr (5 g/kg BW) or vehicle, by gavage, for 6 days. Soleus and extensor digitorum longus (EDL) muscles were removed and incubated for evaluation of ROS content using Amplex-UltraRed reagent. The analysis of expression and activity of antioxidant enzymes (superoxide dismutase 1 and 2, catalase and glutathione peroxidase) were performed. Direct scavenger action of Cr on superoxide radical and hydrogen peroxide was also investigated. Short-term Cr supplementation attenuated ROS content in both soleus and EDL muscles (by 41 and 33.7%, respectively). Cr supplementation did not change expression and activity of antioxidant enzymes. Basal TBARS content was not altered by Cr supplementation. In cell-free experiments, Cr showed a scavenger effect on superoxide radical in concentrations of 20 and 40 mM, but not on hydrogen peroxide. These results indicate that Cr supplementation decreases ROS content in skeletal muscle possibly due to a direct action of Cr molecule on superoxide radical.

Antihypertensive and antioxidant effects of a single daily dose of sodium nitrite in a model of renovascular hypertension

Dietary nitrite and nitrate have been reported as alternative sources of nitric oxide (NO). In this regard, we reported previously that sodium nitrite added to drinking water was able to exert antihypertensive effects in an experimental model of hypertension in a dose-dependent manner. Taking into consideration that nitrite is continuously converted to nitrate in the bloodstream, here we expanded our previous report and evaluate whether a single daily dose of sodium nitrite could exert antihypertensive effects in 2 kidney-1 clip (2K1C) hypertensive rats. Sham-operated and 2K1C rats were treated with vehicle or sodium nitrite (15 mg/kg/day) for 4 weeks. We evaluated the effects induced by sodium nitrite treatment on systolic blood pressure (SBP) and NO markers such as plasma nitrite, nitrite + nitrate (NOx), cGMP, and blood levels of nitrosyl-hemoglobin. In addition, we also evaluated effects of nitrite on oxidative stress and antioxidant enzymes. Dihydroethidium (DHE) was used to evaluate aortic reactive oxygen species (ROS) production by fluorescence microscopy, and plasma levels of thiobarbituric acid-reactive species (TBARS) were measured in plasma samples from all experimental groups. Red blood cell superoxide dismutase (SOD) and catalase activity were evaluated with commercial kits. Sodium nitrite treatment reduced SBP in 2K1C rats (P < 0.05). We found lower plasma nitrite and NOx levels in 2K1C rats compared with normotensive controls (both P < 0.05). Nitrite treatment restored the lower levels of nitrite and NOx. While no change was found in the blood levels of nitrosyl-hemoglobin (P > 0.05), nitrite treatment increased the plasma levels of cGMP in 2K1C rats (P < 0.05). Higher plasma TBARS levels and aortic ROS levels were found in hypertensive rats compared with controls (P < 0.05), and nitrite blunted these alterations. Lower SOD and catalase activities were found in 2K1C hypertensive rats compared with controls (both P < 0.05). Nitrite treatment restored SOD activity (P < 0.05), whereas catalase was not affected. These data suggest that even a single daily oral dose of sodium nitrite is able to lower SBP and exert antioxidant effects in renovascular hypertension.

Bioactive compounds and phenolic-linked functionality of powdered tropical fruit residues

Tropical fruit residues consisting of seeds, peels and residual pulp generated as by-products of fruit processing industry were investigated for bioactive compounds, the in vitro antioxidant capacity as well as alpha-glucosidase and alpha-amylase inhibitory activities. Cyanidin, quercetin, ellagic acid (EA) and proanthocyanidins were found in acerola, jambolan, pitanga and caja-umbu residue powders. Acerola powder had the highest phenolic content (8839.33 mg catechin equivalents (CE)/100 g) and also high-ascorbic acid (AA) concentration (2748.03 mg/100 g), followed by jambolan and pitanga. The greatest 1,1-Diphenyl-2-picrylhydrazyl (DPPH) inhibition was observed for jambolan (436.76 mmol Trolox eq/g) followed by pitanga (206.68 mmol Trolox eq/g) and acerola (192.60 mmol Trolox eq/g), while acerola had the highest ferric reducing antioxidant power (FRAP) assay result (7.87 mmol Trolox eq/g). All fruit powders exhibited enzymatic inhibition against alpha-amylase (IC50 ranging from 3.40 to 49.5 mg CE/mL) and alpha-glucosidase (IC50 ranging from 1.15 to 2.37 mg CE/mL). Therefore, acerola, jambolan and pitanga dried residues are promising natural ingredients for food and nutraceutical manufacturers, due to their rich bioactive compound content.

Stability of Carotenoids, Total Phenolics and In Vitro Antioxidant Capacity in the Thermal Processing of Orange-Fleshed Sweet Potato (Ipomoea batatas Lam.) Cultivars Grown in Brazil

Intervention strategies regarding the biofortification of orange-fleshed sweet potato, which is a rich source of carotenoids for combating vitamin A deficiency, are being developed in Brazil. This study was conducted to evaluate the concentrations of individual carotenoids, total phenolic compounds and antioxidant capacity in the roots of four biofortified sweet potato cultivars that were raw or processed by four common heat treatments. HPLC, Folin-Ciocalteu, DPPH and ABTS assays were used. All cultivars showed high levels of carotenoids in raw roots, predominantly all-trans-beta-carotene (79.1-128.5 mg.100 g(-1) DW), suggesting a high estimated vitamin A activity. The CNPH 1194 cultivar reported carotenoids values highest than those of other cultivars (p < 0.05). The total phenolic compounds varied among cultivars and heat treatments (0.96-2.05 mg.g(-1) DW). In most cases, the heat treatments resulted in a significant decrease in the carotenoids and phenolic compounds contents as well as antioxidant capacity. Processing of flour presented the greatest losses of major carotenoids and phenolics. The phenolic compounds showed more stability than carotenoids after processing. There were significant correlations between the carotenoids and phenolic compounds and the antioxidant capacity.

PHYSIOLOGICAL CHANGES IN SEEDS AND ANTIOXIDANT METABOLISM OF LETTUCE SEEDLING EXPOSED TO THE ACTION OF Zantedeschia aethiopica Spreng. LEAF EXTRACT

This work aimed to evaluate the influence of different concentrations of Zantedeschia aethiopica Spreng. extract on the physiological performance of the seed and on the response of the antioxidant metabolism of lettuce seedlings. The treatments consisted of leaves extracts from Z. aethiopica at concentrations of 0, 6, 12, 25 and 50%. Germination, first germination count, germination speed and index, length of shoot and radicle, seedling total dry mass, chlorophyll content, activity of superoxide dismutase, catalase and ascorbarte peroxidase enzymes, lipid peroxidation, hydrogen peroxide quantification and seedling emergence, length of organs, and total dry mass of seedlings were evaluated. The percentage of germination, the length of the shoot and radicle of seedlings and the total dry mass of seedlings grown in the greenhouse were reduced as the concentration of the extract increased. There were increases of electrical conductivity, of superoxide dismutase, catalase and ascorbate peroxidadase enzymes and the amount of hydrogen peroxide and lipid peroxidation in seedlings with increasing extract concentration. The extract reduced the physiological quality of lettuce seeds and induced an increased production of hydrogen peroxide in seedlings, which increased the activity of antioxidant enzymes that were not effective in tissue detoxification, resulting in cellular damage and increased numbers of abnormal seedlings.

Antioxidant Effects of Quercetin and Catechin Encapsulated into PLGA Nanoparticles

Polymeric nanoparticles (PLGA) have been developed for the encapsulation and controlled release of quercetin and catechin. Nanoparticles were fabricated using a solvent displacementmethod. Physicochemical properties were measured by light scattering, scanning electron microscopy and zeta-potential, X-ray diffraction, infrared spectroscopy and differential scanning calorimetry. Encapsulation efficiency and in vitro release profiles were obtained from differential pulse voltammetry experiments. Antioxidant properties of free and encapsulated flavonoids were determined by TBARS, fluorescence spectroscopy and standard chelating activity methods. Relatively small (d approximate to 400 nm) polymeric nanoparticles were obtained containing quercetin or catechin in a non-crystalline form (EE approximate to 79%) and the main interactions between the polymer and each flavonoid were found to consist of hydrogen bonds. In vitro release profiles were pH-dependant, the more acidic pH, the faster release of each flavonoid from the polymeric nanoparticles. The inhibition of the action of free radicals and chelating properties, were also enhanced when quercetin and catechin were encapsulated within PLGA nanoparticles. The information obtained from this study will facilitate the design and fabrication of polymeric nanoparticles as possible oral delivery systems for encapsulation, protection and controlled release of flavonoids aimed to prevent oxidative stress in human body or food products.

Medium Light and Medium Roast Paper-Filtered Coffee Increased Antioxidant Capacity in Healthy Volunteers: Results of a Randomized Trial

We compared the effects of medium light roast (MLR) and medium roast (MR) paper-filtered coffee on antioxidant capacity and lipid peroxidation in healthy volunteers. In a randomized crossover study, 20 volunteers consumed 482 +/- 61 ml/day of MLR or MR for four weeks. Plasma total antioxidant status (TAS), oxygen radical absorbance capacity (ORAC), oxidized LDL and 8-epi-prostaglandin F2 alpha, erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activity were measured at baseline and after the interventions. MLR had higher chlorogenic acids-(CGA; 334 mg/150 mL) and less caffeine (231 mg/150 ml) than MR had (210 and 244 mg/150 ml, respectively). MLR also had fewer Maillard reaction products (MRP) than MR had. Compared with baseline, subjects had an increase of 21 and 26 % in TAS, 13 and 13 % in CAT, 52 and 75 % in SOD, and 62 and 49 % in GPx after MLR and MR consumption (P < 0.001), respectively. ORAC increased after MLR (P = 0.004). No significant alteration in lipid peroxidation biomarkers was observed. Both coffees had antioxidant effects. Although MLR contained more CGA, there were similar antioxidant effects between the treatments. MRP may have contributed as an antioxidant. These effects may be important in protecting biological systems and reducing the risk of diseases related to oxidative stress.

The in vitro antioxidant properties of the Al-quercetin/beta CD and Al-catechin/beta CD inclusion compounds, rationalized in terms of their electrochemical behaviour

Inclusion compounds of Al-quercetin and Al-catechin complexes with beta-cyclodextrin (beta CD) were investigated. The complex and the inclusion compound of quercetin are more effective DPPHaEuro cent scavengers than the corresponding catechin compounds and the inclusion does not compromise their scavenging abilities, with only a slight decrease in the EC50 values. This is in accordance with the electrochemical data, which revealed that the inclusion compounds have lower diffusion coefficients in aqueous solution than the non-included compounds. For the quercetin compounds, some spectroscopic properties were also addressed by means of UV-visible and NMR measurements in aqueous media.

ANALYSIS OF IN VITRO AND IN VIVO ANTIOXIDANT PROPERTIES OF HYDROPHILIC FRACTIONS FROM THE SEAWEED HALIMEDA MONILE L.

In this work, in vitro and in vivo antioxidant properties of the marine algae Halimeda monile were assessed and the levels of some of its compounds likely to be responsible for such properties were determined. The estimated contents of total polyphenols, chlorophylls a and b and carotenoids were 179.5, 356.3, 452.8 and 42.2 mu g/g dry weight seaweed, respectively. The presence of terpenoids and flavonoids was also observed. The antioxidant activity of two polar fractions from H. monile (lyophilized aqueous extract and free phenolic acid fraction) was evaluated using three antioxidant assays: ferric reducing antioxidant power, 1,1-diphenyl-2-picrylhydrazyl and lipid peroxidation. Treatment of CCl4-induced liver damage in rats with extracts resulted in lower serum thiobarbituric acid-reactive substances levels and higher hepatic glutathione concentrations compared to those observed in the CCl4-treated group. Also, a significant increase in catalase activity was detected after treatment with the extracts. These results suggest that the seaweed H. monile could be a potential source for natural antioxidants.

Antioxidant capacity and environmentally friendly synthesis of dihydropyrimidin-(2H)-ones promoted by naturally occurring organic acids

The Biginelli reaction is a multicomponent reaction involving the condensation between an aldehyde, a beta-ketoester, and urea or thiourea, in the presence of an acid catalyst, producing dihydropyrimidinones (DHPMs). Owing to their important pharmacological properties, the DHPMs have been studied by many authors. However, most of the methodologies used for the synthesis of these compounds require drastic reaction conditions. In the current study, we report an efficient and clean procedure for preparing DHPMs by the use of citric acid or tartaric acid as a promoter of the Biginelli synthesis in ethanol as solvent. In addition, we have evaluated the antioxidant capacity of the compounds synthesized by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay and the thiobarbituric acid-reactive species test. Two compounds presented antioxidant activity and also reduced lipid peroxidation at concentrations of 200 and 300 mu M. In summary, we report an environmentally friendly procedure for the preparation of DHPMs and demonstrate the antioxidant capacity of some of the compounds. (C) 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:155161, 2012; View this article online at . DOI 10.1002/jbt.20424