Free radical-scavenging activity of Aloe vera (Aloe barbadensis Miller) extracts by supercritical carbon dioxide extraction

The free radical-scavenging activities of extracts of Aloe vera of leaf skin by supercritical CO₂ extraction and solvent extraction were determined. An orthogonal array design matrix of L₉ (3⁴) was considered to optimize supercritical carbon dioxide extraction processing at a CO₂ flow rate of 12–36 l h⁻¹, 35–45 MPa and 32–50 °C. The optimum extracted yield of 1.47% was provided at 50 °C 36 l h⁻¹, 35 MPa and 20% of modifier of methanol. These four factors were all demonstrated to be significantly crucial in the supercritical carbon dioxide extraction operation, as two-variable interactions. The extracts of A. vera rind by supercritical carbon dioxide extraction and solvent extracts provided significantly higher free radical-scavenging activities of 33.5% and 39.7%, respectively, than extracts of A. vera gel extracted by ethanol with a free radical-scavenging activity of 14.2%. The inhibition percentage of extracts of A. vera and reference antioxidants followed the decreasing order: Trolox (76.8%) > ethanol extracts of A. vera skin (39.7%) > BHT (35.9%) > the extract of supercritical carbon dioxide extraction (33.5%) >α-tocopherol (25.6%) > ethanol extracts of A. vera pulp (14.2%). Compared to BHT and α-tocopherol, the extracts of A. vera skin, by supercritical carbon dioxide extraction and ethanol, showed stronger antioxidant activities. Components in the rind of A. vera are responsible for the higher antioxidant activity of A. vera extracts.     

Evaluation and improvement of antioxidant and antibacterial activities of supercritical extracts from clove buds

For the first time, extracts from clove buds obtained by supercritical carbon dioxide extraction were screened for antioxidant and antibacterial activities. Additionally, antioxidant and antibacterial activities of extracts obtained by the supercritical extraction of the clove bud–oregano leaf mixtures were studied. Supercritical extract of pure clove had the highest eugenol (64%) and total phenolic content (530.56 mg GAE/g_extract). All extracts had antioxidant activity comparable to synthetic antioxidants against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and formation of peroxides. Presence of 0.6% and 5% of oregano extract in the clove extracts obtained from the clove–oregano plant mixtures improved their antioxidant activity with respect to the extract from pure clove. Clove extract showed moderate antibacterial activities against selected Staphylococcus and Enterococcus bacterial strains. Presence of 50% of the oregano extract improved antibacterial activity of clove extract against all tested strains and resulted in a synergistic antibacterial activity against Methicillin-resistant Staphylococcus haemolyticus strain (MIC ? 1.25 μg/mL). Study demonstrated great potential of supercritical clove extract as natural functional ingredient and the possibility of increasing its antioxidant and antibacterial efficiencies in order to apply lower concentrations and to reduce undesirable flavour notes and toxicological effects in final products.     

PET trays coated with Citrus extract exhibit antioxidant activity with cooked turkey meat

A natural Citrus extract with potential antioxidant activity was evaluated as an ingredient for the production of active food packaging. The extract, in methanol, was sprayed onto the surface of polyethylene terephthalate (PET) trays. For comparison, a second set of trays were prepared using α-tocopherol as the coating. The effectiveness of the two types of packaging in delaying lipid oxidation in cooked turkey meat slices, stored at 4 °C over 4 days, was compared using 2-thiobarbituric acid-reactive substances (TBARS) and hexanal assays. TBARS and hexanal values, for meat stored on the Citrus extract coated trays, were significantly lower (P < 0.01) than those of meat stored on uncoated (control) trays while α-tocopherol coated trays exhibited no significant effect compared to control trays (P > 0.05). The effectiveness of the Citrus extract coating, compared to the α-tocopherol coating, was attributed to its higher surface roughness, demonstrated by optical profilometry, and the higher level of release (solubility) of the antioxidant in water.     

Analysis of antioxidant activity and antioxidant constituents of Chinese toon

Antioxidant activity of the methanol and water extracts of Chinese toon (Toona sinensis) leaf was evaluated using DPPH radical scavenging and lipid peroxidation assays. Contents of four major types of antioxidants including β-carotene, ascorbate, α-tocopherol and phenolics were also quantified. Open column chromatography followed by semi-preparative HPLC were applied to separate phenolic antioxidants whose contents were subsequently determined by HPLC. The methanol extract demonstrated much higher antioxidant activity than the water extract. Contents of β-carotene, ascorbate, α-tocopherol and phenolics were 1.23 μmol g^?1, 34.2 μmol g^?1, 2.40 μmol g^?1 and 872 μmol gallic acid equivalents g^?1, respectively. Six phenols were isolated. Their structures were characterized as 5-O-galloylquinic acid, gallic acid, methyl gallate, β-1,2,6-tri-O-galloyl-d-glucose, quercetin 3-O-β-d-glucopyranoside and quercetin 3-O-(2′′-O-galloyl)-β-d-glucopyranoside, respectively. The results indicate that phenolic compounds are the dominant antioxidants in Chinese toon. The compounds β-1,2,6-tri-O-galloyl-d-glucose and quercetin 3-O-(2′′-O-galloyl)-β-d-glucopyranoside were reported for the first time in Chinese toon.     

Antioxidant and type II diabetes related enzyme inhibition properties of methanolic extract of an underutilized food legume,Canavalia ensiformis (L.) DC: Effect of traditional processing methods

The methanolic extract of Canavalia ensiformis (L.) DC (Jack bean) seed, an underutilized food legume collected from India was analyzed for antioxidant and health relevant functional properties. The raw seeds contained total free phenolic content of 12.98 ± 1.63 g catechin equivalent/100 g extract DM. The raw seed extract exhibited ferric reducing/antioxidant power (FRAP, 1218 mmol Fe[II]/mg extract), inhibition of β-carotene degradation (49.81%), radical scavenging activity against DPPH (56.78%) and superoxide (35.89%). In addition, 77.56% of α-amylase and 75.45% of α-glucosidase enzyme inhibition characteristics were found under in vitro starch digestion bioassay. Sprouting + oil-frying caused an apparent increase on the total free phenolic content with significant improvement on antioxidant and free-radical scavenging capacity, while soaking + cooking as well as open-pan roasting treatments showed diminishing effects. Inhibition of α-amylase and α-glucosidase enzyme activities were declined to 22.69 and 42.69%, respectively during sprouting + oil-frying treatment is more desirable for the dietary management of type II diabetic patients.     

Thermal and light stabilities and antioxidant activity of carotenoids from tomatoes extracted using an ultrasound-assisted completely solvent-free method

The use of petroleum-derived solvents, particularly volatile organic compounds (VOCs), in the chemical industry has increased the contamination and residual effects of these solvents. Ionic liquids (ILs) can potentially replace VOCs, thereby reducing the risks of environmental contamination and toxicity. In this context, the objectives of this study were as follows: 1 — to obtain an ionic liquid for use in extracting carotenoids from tomatoes with ultrasound assistance; and 2 — to determine the stability and antioxidant activity of tomato carotenoid extracts. Ultrasound can also efficiently extract carotenoid compounds with ionic liquids in comparison with conventional VOC solvents (obtained from an all-trans-lycopene 7.5–8.0 μg·g^− 1 tomato sample by IL and 6.2–7.7 μg·g^− 1 by acetone). Similarly, the activation energies (E_a) in aqueous medium were obtained for the IL carotenoid extract (10.8 kJ·mol^− 1) and acetone carotenoid extract (9.4 kJ·mol^− 1). The antioxidant activities of the tomato carotenoid extract were 7.4 and 12.4 relative to α-tocopherol for the ionic liquid extract and acetone extract, respectively. The combination of chromatographic analysis and degradation kinetics provided data for positive assessment similarity of thermal and light stabilities of tomato carotenoids extracted by IL and extracted by acetone.     

Sensory evaluation of egg products and eggs laid from hens fed diets with different fatty acid composition and supplemented with antioxidants

Is the sensory quality of eggs influenced by adding vegetable lipids, animal and vegetable sources of n − 3 polyunsaturated fatty acids (n − 3 PUFA), and/or natural antioxidants to the hens diet? To answer this question three feeding experiments were conducted adding either palm butter, grape seed oil, flax seed oil, n − 3 PUFA such as flax seed and marine algae and the natural antioxidant rosemary to the hens diet. For each experiment a standard diet was used as control. The results suggested that vegetable lipids (palm butter, grape seed, flax seed), n − 3 PUFA (flax seed and marine algae) and rosemary may be used to hens fed diet without affecting the sensory properties of eggs.The sensory quality of eggs was evaluated on hard boiled, scrambled eggs and Madeira cake.In this work, we report the first sensory characterization of eggs and products containing eggs obtained from hens diet based on grape and algae plus vitamin E and rosemary extract.     

Oxidative stabilization of ultra-high omega-3 concentrates as ethyl esters or triacylglycerols

A comparative study of the oxidative stability of “ultra-high” ω3 concentrates (80%) from fish oils as triacylglycerols (TAG) or ethyl esters (EE), as well as their stabilization by supercritical extracts of rosemary (SER), α-tocopherol or their mixture, by Rancimat method and throughout storage time, was carried out. No significant differences were found between EE and TAG on oxidative stability when measured by Rancimat conditions in the range of 50?90 °C. However, storage experiments revealed a poor stability of the EE concentrate form, measured by the monitorization of peroxide and p-anisidine values. Concerning the stabilization by antioxidants, there was a lack of antioxidant effect of evaluated compounds when Rancimat assays were performed at 70 °C, whereas an antioxidant effect began to evidence at 60 °C, and a clearest antioxidant protection was measured at 50 °C for the mixture of the SER plus α-tocopherol in both EE and TAG forms. This selected binary mixture efficiently stabilized the ω3-TAG concentrate throughout 50 days of storage conditions, whereas the stabilization of ω3-EE concentrate was worse. Therefore, the combination of SER and α-tocopherol seemed to be a good antioxidant mixture for the efficient stabilization of extremely labile ultra-high ω3 concentrates, especially in the form of ω3 TAG oils.     

Antioxidant properties of methanolic extracts from Ganoderma tsugae

Ganoderma tsugae Murrill was available in the form of mature and baby Ling chih, mycelia and fermentation filtrate. From these four forms, methanolic extracts were prepared and their antioxidant properties were studied. Methanolic extracts from mature and baby Ling chih showed high antioxidant activities (96.8% and 93.6%) at 20 mg ml⁻¹, and had EC₅₀ values of 0.53 and 1.11 mg ml⁻¹, respectively. EC₅₀ values in reducing power were 5.00, 2.28, 0.93 and 2.15 mg ml⁻¹ for Ling chih, baby Ling chih, mycelia and filtrate, respectively. Methanolic extracts from mature and baby Ling chih scavenged 1,1-diphenyl-2-picrylhydrazyl radicals by 88.4% and 93.8% at 5 mg ml⁻¹, whereas those from mycelia and filtrate scavenged by 85.7% and 79.3% at 10 mg ml⁻¹, respectively. EC₅₀ values in chelating ability on ferrous ions were 4.82, 3.05, 1.10 and 3.41 mg ml⁻¹ for Ling chih, baby Ling chih, mycelia and filtrate, respectively. Total phenols were the major naturally occurring antioxidant components found in all methanolic extracts and in the range of 24.0–35.6 mg g⁻¹. Based on EC₅₀ values, G. tsugae was good in antioxidant properties except for the scavenging ability on hydroxyl radicals.     

Changes In Plasma α-Tocopherol and Selenium of Gestating Cows Fed Hay or Silage

The effects of dietary hay or silage on plasma α-tocopherol and Se concentrations during late gestation and early lactation were studied using 40 crossbred pregnant cows and their calves. Cows received solely either timothy hay or grass silage forage from midgestation to early lactation and 21 d prior to estimated calving were or were not injected with Se (30 mg) and α-tocopherol (3000 IU). Five blood samples were collected for determination of concentrations of α-tocopherol and Se twice during late gestation and three times after calving. Blood samples from calves were collected at birth and at 10 and 30 d of age. Serum concentrations of α-tocopherol were low at birth for both groups of calves and ranged from .83 to 1.08 μg/ml of plasma. Hay had less α-tocopherol than silage (15 vs. 35 ppm in the DM). Cows fed silage had significantly higher plasma α-tocopherol concentrations (3.41 μg/ml) than cows fed hay (2.25 μg/ml). Cows given one subcutaneous injection of Se plus α-tocopherol preparation had significantly higher Se concentration in plasma (30 ng/ml) than did cows in the control group (17 ng/ml). The Se concentration in the placenta of cows that were injected with the Se preparation was significantly higher (64 ppm) than that in the control (47 ppm). Plasma Se concentration of calves at birth was correlated significantly with that of dams soon after parturition.     

Food matrices affect the bioavailability of (n − 3) polyunsaturated fatty acids in a single meal study in humans

The aim of this study was to investigate the role of the food matrix on bioavailability of (n − 3) PUFA and oxidative stress in plasma. The study was a randomized, cross-over study and included 12 healthy male participants. The participants ingested a test meal, which consisted of a fitness bar, a yoghurt drink, eight oil capsules, bread and butter; 4 g of fish oil was incorporated into one of the matrices. Blood samples were collected and fatty acid composition of chylomicrons was determined together with plasma levels of conjugated dienes and α-tocopherol. Fish oil incorporated into food products were absorbed differently from those simply administered as supplements alongside of food products, and yoghurt was the best matrix for providing fast absorption of lipids in general, including (n − 3) fatty acids. No significant difference was observed in the level of plasma α-tocopherol after ingestion of test meals.     

Antioxidants from a Chinese medicinal herb – Psoralea corylifolia L

The powder and extracts of Psoralea corylifolia L. were tested in lard at 100 °C by using the oxidative stability instrument (OSI) and were found to have strong antioxidant effects. Six compounds, bakuchiol, psoralen, isopsoralen, corylifolin, corylin and psoralidin were isolated from the herb and identified by UV, IR, Mass, ¹H and ¹³C NMR spectra and melting point. Their antioxidant activities were investigated individually and compared with butylated hydroxytoluene (BHT) and α-tocopherol by the OSI at 100 °C. The results showed that bakuchiol, corylifolin, corylin and psoralidin had strong antioxidant activities, and especially psoralidin (stronger antioxidant property than BHT), but psoralen and isopsoralen had no antioxidant activities at 0.02% and 0.04% levels. The antioxidant activities of the compounds decrease in the following order: Psoralidin > BHT > α-tocopherol > bakuchiol > corylifolin > corylin > isopsoralen ∼ psoralen.     

Development of active packaging containing natural antioxidants

Two active packagings, consisting of PET trays sprayed with citrus fruit extract and α-tocopherol, were developed and tested. A comparison of the antioxidant activity of the two packagings was carried out on cooked meat stored at 4 °C. Lipid oxidation in citrus fruit extract-coated trays, measured with TBARS analysis, was significantly lower (p<0.01) than in uncoated (control) trays. Trays coated with α-tocopherol did not show any antioxidant activity. Morphology examination showed a more irregular coating for citrus fruit extract. Different orientations of the active phenolic groups on the PET surface could explain the differences in antioxidant efficacy of the two packagings.     

Evaluation of antioxidant activity of parsley (Petroselinum crispum) essential oil and identification of its antioxidant constituents

Antioxidant capacities of the essential oil extracted from parsley (Petroselinum crispum) were evaluated by three different in vitro assays: β-carotene bleaching assay, DPPH free radical scavenging assay and Fe²⁺-metal chelating assay. Results showed that the parsley oil (PO) possessed a certain degree of antioxidant activities in terms of β-carotene bleaching capacity and free radical scavenging activity, but its metal chelating capacity was negligible. The antioxidant EC₅₀ values of the β-carotene bleaching assay and DPPH free radical scavenging assay of the crude PO dissolved in methanol were measured in about 5.12 and 80.21 mg/mL, respectively. However, these values were much weaker than those of BHT in 0.01 and 0.58 mg/mL, and of α-tocopherol in 0.01 and 0.10 mg/mL. Isolation and identification of the inherent antioxidants in PO involved using various chromatographic techniques including silica gel open column chromatography, normal phase-HPLC and GC–MS. Myristicin in PO was found as a dominant compound (32.75%) that exhibited a moderate antioxidant activity. Apiol was the second dominant compound (17.54%), but it might be the major contributor to the antioxidant activity of PO. These results suggest that the PO and its two major components can be potential alternative natural antioxidants.     

The effect of Yucca schidigera extract on the physical structure and on the oxidative stability of sugar-candy foam products

The influence of water extract of yucca (Yucca schidigera Roezl.) powder on foaming potential, structure of sugar-candy foam and its stability during the shelf-life was researched. Water extract of yucca powder (1:7 w/v) contained 0.102 mg/ml of steroidal saponins. This was added to sugar-candy foam in concentration equivalent of 50 and 100 ppm saponins. In parallel, similar sugar-candy foam was prepared by adding 200 ppm of α-tocopherol or in a traditional way but without any additives. It was shown that yucca extract had beneficial influence on the structure (dry matter content, hardness, density and porosity) of sugar-candy foam products both in newly prepared as well as in candies stored over two months period. Moreover, antioxidant properties of yucca extract were much stronger than those shown by α-tocopherol and allowed to maintain freshness of candies for 2-months period. This indicates that yucca water extract might be a beneficial natural ingredient improving both quality and stability of sugar-candy foam products.     

Citharexylum solanaceum fruit extracts: Profiles of phenolic compounds and carotenoids and their relation with ROS and RNS scavenging capacities

Citharexylum solanaceum is a native fruit from Brazil, which both bioactive compounds and antioxidant potential were not yet investigated. Thus, the freeze-dried extracts of seed and pulp + skin of C. solanaceum fruits were obtained after solid-liquid extraction with ethanol and their bioactive compounds composition, namely phenolic compounds and carotenoids, were determined. The antioxidant capacity of both extracts against physiologically relevant reactive oxygen species (ROS) and reactive nitrogen species (RNS) was further investigated. Both C. solanaceum extracts showed high contents of phenolic compounds; however, pulp + skin extract presented 2.4-times more phenolic compounds (33.54 mg/g) than the seed extract (14.09 mg/g). Verbascoside (phenylpropanoid) was the major compound identified in both extracts (11–25 mg/g). Regarding the carotenoid composition, all-trans-lutein (14–42 μg/g) and all-trans-β-carotene (13–44 μg/g) were the major compounds in both extracts. The high content of phenolic compounds and carotenoids in pulp + skin extract might explain its higher scavenging capacity against all the ROS/RNS as compared to seed extract. In general, both extracts showed better scavenging capacity for the RNS than for the ROS. Our results indicate that C. solanaceum fruits can be explored as an important natural source of antioxidant compounds.     

Enzymatic synthesis of banana flavour (isoamyl acetate) by Bacillus licheniformis S-86 esterase

New carboxylesterase from organic-solvent-tolerant Bacillus licheniformis S-86 strain was characterized. The enzyme named as type II esterase showed an optimal activity in the temperature range 60–65 °C and pH 8.0. The enzyme was moderatly thermostable (half-life of 1 h at 50 °C), but remarkable stable at extremely alkaline pH, retaining 100% of its activity at pH 10.0–11.0. Furthermore, the esterase showed high stability in detergents (86% residual activity in 10% SDS), and also 0.1% ionic and non-ionic detergents are inducers of enzyme activity. PMSF, a serine protease inhibitor, did not show any effect on the activity. The immobilized type II esterase was able to synthesize isoamyl acetate from isoamyl alcohol and p-nitrophenyl acetate (acyl donor) in n-hexane. The resulting ester yield (42.8%), obtained at a low temperature (28 °C) and with a very low amount of enzyme (4.6 × 10^?5 mg ml^?1), indicates a high potential for type II esterase in isoamyl acetate synthesis for production purposes.     

Inactivation of Escherichia coli O157:H7 by cinnamic aldehyde purified from Cinnamomum cassia shoot

Escherichia coli O157:H7 is a pathogen, which causes the hemorrhagic colitis, hemolytic uremic syndrome and thrombotic thrombocytopenic purpura in humans. Control of the bacterial cells in foods is an important factor to reduce outbreaks of the foodborne diseases. In this study, cinnamic aldehyde possessing antimicrobial activity against the bacterial cells was purified from the extract of cinnamon (Cinnamomum cassia Blume) shoot by sequential fractionation with various solvents and silica gel column chromatography. When E. coli O157:H7 cells were incubated at 37°C for 12 h in the presence of 500 μg ml⁻¹ of the purified from cinnamic aldehyde, the viable counts decreased dramatically (from 4.9×10⁶ to 1.0×10² cfu ml⁻¹). In the presence of 1000 μg ml⁻¹ of the substance, most of the cells were killed after 2 h of incubation suggesting that the antimicrobial activity of cinnamic aldehyde is bacteriocidal in E. coli. Scanning electron microscopic observations revealed that the bacterial cells treated with the cinnamic aldehyde suffered from severe damages in their surface structure. Minimal inhibitory concentration of the cinnamic aldehyde was determined to be 250 μg ml⁻¹ against E. coli strains O157:H7 and O26 or 500 μg ml⁻¹ against strains ATCC11105 and O111.     

Antioxidant activity of dulse (Palmaria palmata) extract evaluated in vitro

Palmaria palmata (dulse) is traditionally consumed as a snack food and garnish; but, little is known about its potential as a source of antioxidants. A 1-butanol soluble fraction extracted from dulse exhibited OH scavenging activity ± EDTA (non-site and site specific activity) in a deoxyribose assay. EC₅₀ concentrations of dulse extract to quench DPPH and ABTS⁺ free radicals were 12.5 and 29.5 mg/ml. Dulse extract inhibited (p < 0.05) conjugated diene production in a linoleic acid emulsion at 24, 48 and 52 h, 38 °C; and inhibited (p = 0.044) thiobarbituric acid reactive substances (TBARS) production at 52 h. One milligram dulse extract exhibited reducing activity = 9.68 μg l-ascorbic acid and total polyphenol content = 10.3 μg gallic acid; the dulse extract did not chelate transition metal ions. The antioxidant activity of the dulse extract was associated with aqueous/alcohol-soluble compounds characterized by phenolic functional groups with reducing activity.