Carotenoids are Effective Inhibitors of in vitro Hemolysis of Human Erythrocytes,as Determined by a Practical and Optimized Cellular Antioxidant Assay

β‐Carotene, zeaxanthin, lutein, β‐cryptoxanthin, and lycopene are liposoluble pigments widely distributed in vegetables and fruits and, after ingestion, these compounds are usually detected in human blood plasma. In this study, we evaluated their potential to inhibit hemolysis of human erythrocytes, as mediated by the toxicity of peroxyl radicals (ROO?). Thus, 2,2′‐azobis (2‐methylpropionamidine) dihydrochloride (AAPH) was used as ROO? generator and the hemolysis assay was carried out in experimental conditions optimized by response surface methodology, and successfully adapted to microplate assay. The optimized conditions were verified at 30 × 10⁶ cells/mL, 17 mM of AAPH for 3 h, at which 48 ± 5% of hemolysis was achieved in freshly isolated erythrocytes. Among the tested carotenoids, lycopene (IC₅₀ = 0.24 ± 0.05 μM) was the most efficient to prevent the hemolysis, followed by β‐carotene (0.32 ± 0.02 μM), lutein (0.38 ± 0.02 μM), and zeaxanthin (0.43 ± 0.02 μM). These carotenoids were at least 5 times more effective than quercetin, trolox, and ascorbic acid (positive controls). β‐Cryptoxanthin did not present any erythroprotective effect, but rather induced a hemolytic effect at the highest tested concentration (3 μM). These results suggest that selected carotenoids may have potential to act as important erythroprotective agents by preventing ROO?‐induced toxicity in human erythrocytes.     

Evaluation of the antioxidant and antiproliferative activities of extracted saponins and flavonols from germinated black beans (Phaseolus vulgaris L.)

Flavonoids and saponins from common beans have been widely studied due to their bioactivity. This research evaluated the effect of germination of black beans (Phaseolus vulgaris L.) on the antioxidant capacity and antiproliferative activity against cancer cell lines of saponins and flavonoids extracted from seed coats, cotyledons and sprouts. Principal component analysis was performed to achieve punctual associations between the black bean saponins and flavonoids concentrations to the antioxidant capacity and the antiproliferative activities. Total phenolic content and antioxidant capacity of extracts were higher when obtained from seed coats, mainly from the 3rd germination day. The extracts obtained from seed coats after 3 and 5 germination days inhibited all cancer cell lines proliferation with no cytotoxicity against control cells. Genistein was related with the activity against mammary cancer cells but flavonols and group B saponins were more related with hepatic and colon cancers. Non-glycosilated flavonols were related with antioxidant capacity.     

Metabolic profile and biological activities of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco: Studies on the essential oil and polar extracts

We investigated the metabolic profile and biological activities of the essential oil and polar extracts of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco collected in south Portugal. Gas chromatography–mass spectrometry (GC–MS) analysis revealed that oxygen-containing monoterpenes was the principal group of compounds identified in the essential oil. Camphor (40.6%) and fenchone (38.0%) were found as the major constituents. High-performance liquid chromatography with diode array detection (HPLC–DAD) analysis allowed the identification of hydroxycinnamic acids (3-O-caffeoylquinic, 4-O-caffeoylquinic, 5-O-caffeoylquinic and rosmarinic acids) and flavones (luteolin and apigenin) in the polar extracts, with rosmarinic acid being the main compound in most of them. The bioactive compounds from L. pedunculata polar extracts were the most efficient free-radical scavengers, Fe²⁺ chelators and inhibitors of malondialdehyde production, while the essential oil was the most active against acetylcholinesterase. Our results reveal that the subspecies of L. pedunculata studied is a potential source of active metabolites with a positive effect on human health.     

Preparation of high molecular weight poly(vinyl pivalate) with high yield and high molecular weight poly(vinyl alcohol) by emulsion polymerization of vinyl pivalate and saponification

To prepare high molecular weight (HMW) poly(vinyl pivalate) (PVPi) with high yield and high linearity which is a promising precursor for syndiotactic poly (vinyl alcohol) (PVA), vinyl pivalate (VPi) was emulsion polymerized, using 2,2′‐azobis(2‐amidinopropane) dihydrochloride (AAPH) as an initiator and sodium dodecyl sulfate (SDS) as an emulsifier. The effect of the polymerization conditions on the conversion, molecular weight, and degree of branching was investigated. PVA with maximum number‐average degree of polymerization (P_n) of 6200 could be prepared by complete saponification of PVPi, with P_n of 13,300–16,700 obtained at polymerization temperature of 50°C, using SDS and AAPH concentration of 2.0 × 10^?3 mol/L of water and 1.0 × 10^?3 mol/L of water, respectively, and the maximum conversion was about 90%. From the emulsion polymerization of VPi, spherical PVPi with high yield was effectively prepared, which might be useful for the precursor of syndiotactic PVA micro‐ and nano‐spheres with various surface properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 410–414, 2007     

Changes in strawberry phenolics, anthocyanins, and antioxidant capacity in response to high oxygen treatments

Changes in fruit quality, decay, phenolic and anthocyanin content, and antioxidant capacity of strawberries (Fragaria × ananassa Duch. cv. Allstar) stored under air and high oxygen atmospheres at 5 °C were investigated. Freshly harvested strawberries were placed in jars and ventilated continuously with air or with 40, 60, 80, or 100 kPa O₂ at 5 °C for up to 14 days. Samples were taken initially, and after 3, 7, 10 and 14 days of storage. While fruit quality parameters such as titratable acidity, total soluble solids and surface color were only slightly affected by differing levels of O₂, the higher oxygen concentration treatments significantly reduced decay. Oxygen concentrations higher than 60 kPa also promoted increases in ORAC values, total phenolics and total anthocyanins as well as individual phenolic compounds analysed by HPLC during the initial 7 days of storage. However, this effect diminished with prolonged storage. No significant differences in ORAC values, total phenolics, total anthocyanins, or the individual phenolic compounds were observed among the high O₂ and air-stored fruits after 14 days of storage. These results indicate that high oxygen treatments exert the most effects on fruit quality and antioxidant capacity of strawberry fruit in the first 7 days of storage.     

Red wine polyphenols protect n−3 more than n−6 polyunsaturated fatty acid from lipid peroxidation

Moderate red wine consumption is associated with decreased risk for cardiovascular disease; however, the underlying mechanisms are not completely understood. The main aim of this study was to investigate the effects of red wine polyphenols (WP) on the oxidizability of human plasma fatty acids, in particular those most involved in the inflammatory response — archidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The oxidizability of the major fatty acids of plasma was determined by measuring their loss gaschromatographycally during peroxidation kinetics induced by 2′-azobis(2-methylpropionamidine)-dihydrochloride. The capacity of WP to scavenge 1,1,diphenyl-2-picryl-hydrazyl (DPPH), superoxide anion and hydroxyl radicals, and trap total peroxyl radicals in plasma (TRAP) was also measured. WP (1.75–5 μg/mL) inhibited DPPH, superoxide anion and hydroxyl radicals and increased TRAP in a dose-dependent manner. WP (1.75 μg/mL) significantly protected all plasma PUFA from peroxidation but the protection of EPA and DHA was higher than that of AA. These results suggest that the association of WP to apolipoproteins makes EPA and DHA less accessible to hydro-soluble radicals than AA, thus providing a biochemical rationale for future ‘in vivo’ studies on the benefits to health of moderate red wine consumption.     

Antioxidant and antiglycation properties of Passiflora alata and Passiflora edulis extracts

The leaves of Passiflora alata Dryander and Passiflora edulis Sims, traditionally used in American countries to treat both anxiety and nervousness by folk medicine, are rich in polyphenols, which have been reported as natural antioxidants. In this study, the antioxidant activities of P. edulis and P. alata hydroalcoholic leaf extracts were verified in in vitro and ex vivo assays. P. alata showed a higher total reactive antioxidant potential than did P. edulis. The antioxidant activities of both extracts were significantly correlated with polyphenol contents. In addition, both extracts attenuated ex vivo iron-induced cell death, quantified by lactate dehydrogenase leakage, and effectively protected against protein damage induced by iron and glucose. These findings demonstrate that the P. alata and P. edulis leaf extracts have potent in vitro and ex vivo antioxidant properties and might be considered as possible new sources of natural antioxidants.     

The antioxidant properties of the cherimoya (Annona cherimola) fruit

Annona cherimola is an exotic fruit from the genus Annona, native to the Andean highlands in western South America. The cherimoya skin, flesh and juice were isolated and analyzed for antioxidant content using the oxygen radical absorbance capacity (ORAC) assay. The juice showed the highest antioxidant activity, while the flesh exhibited the lowest. The cherimoya skin, flesh and juice extracts were also incubated with Raji (Burkitt's Lymphoma) and HT-29 (colon cancer) cell lines, and the antioxidant uptake of cells was measured. Both cell lines, when subjected to cherimoya juice, showed the highest antioxidant uptake. The cells were then exposed to AAPH, a radical initiator, to simulate the conditions of cells under oxidative stress, and then subjected to cherimoya skin, flesh and juice extracts. Both cell lines absorbed more antioxidants after being pre-exposed to AAPH, indicating that cells under stress have the ability to import antioxidants.     

Evaluation of natural and synthetic compounds according to their antioxidant activity using a multivariate approach

The antioxidant activity of natural and synthetic compounds was evaluated using five in vitro methods: ferric reducing/antioxidant power (FRAP), 2,2‐diphenyl‐1‐picrylhydradzyl (DPPH), oxygen radical absorption capacity (ORAC), oxidation of an aqueous dispersion of linoleic acid accelerated by azo‐initiators (LAOX), and oxidation of a meat homogenate submitted to a thermal treatment (TBARS). All results were expressed as Trolox equivalents. The application of multivariate statistical techniques suggested that the phenolic compounds (caffeic acid, carnosic acid, genistein and resveratrol), beyond their high antioxidant activity measured by the DPPH, FRAP and TBARS methods, showed the highest ability to react with the radicals in the ORAC methodology, compared to the other compounds evaluated in this study (ascorbic acid, erythorbate, tocopherol, BHT, Trolox, tryptophan, citric acid, EDTA, glutathione, lecithin, methionine and tyrosine). This property was significantly correlated with the number of phenolic rings and catecholic structure present in the molecule. Based on a multivariate analysis, it is possible to select compounds from different clusters and explore their antioxidant activity interactions in food products.     

Effect of γ-radiation on green onion DNA integrity: Role of ascorbic acid and polyphenols against nucleic acid damage

The effect of γ-radiation on green onion DNA integrity, phenol content, oxygen radical absorbance capacity, employing pyrogallol red and fluorescein as probes, as well as ascorbic acid content has been evaluated. Measurements using thiazole orange-DNA fluorescence and agarose gel electrophoresis show that γ-radiation does not lead to an apparent DNA change in green onion. However, it was readily cleaved upon irradiation from the previously isolated nucleic acid. Furthermore, green onion exposure to γ-radiation produces slight increases in the polyphenol concentrations (163–188 μM Trolox eq.) and a decrease in the oxygen radical absorbance using fluorescein (from 245 to 200 Trolox eq.) Interestingly, a high ascorbic acid content (364 μM), which decreases by 40% after γ-ray exposure was measured by using pyrogallol-red-based oxygen radical absorbance capacity induction times from green onion aqueous extracts. Thus, our results suggest that ascorbic acid present in green onion plays a fundamental role in the plant antioxidant response toward γ-radiation exposure, while polyphenols remain largely unchanged, as revealed from oxygen radical absorbance capacity, employing pyrogallol red.