Antioxidant activity of tocopherols and phenolic compounds of virgin olive oil

The antioxidant effects of hydrophilic phenols and tocopherols on the oxidative stability in virgin olive oils and in purified olive oil have been evaluated. Total hydrophilic phenols and the oleosidic forms of 3,4-dihydroxyphenolethanol (3,4-DHPEA) were correlated (r=0.97) with the oxidative stability of virgin olive oil. On the contrary, tocopherols showed low correlation (r=0.05). Purified olive oil with the dialdehydic form of elenolic acid linked to 3,4-DHPEA, an isomer of oleuropeine aglycon, and 3,4-DHPEA had good oxidative stability. A synergistic effect was observed in the mixture of 3,4-DHPEA and its oleosidic forms with α-tocopherol in purified olive oil by the Rancimat method at 120°C.     

Antioxidant activity of mediterranean plant leaves: Occurrence and antioxidative importance of α-tocopherol

α-Tocopherol was identified as the main antioxidant in hexane extracts of leaves of sixteen Mediterranean plant species. The α-tocopherol content was determined by a two-step procedure involving column and gas chromatography with α-tocopherol acetate as internal standard. The tocopherol content of the extracts was in the range of 0.0–4.7%, and that of the dry leaves was 0–846 ppm. The highest α-tocopherol content was found in the leaves of a Mediterranean oak,Quercus ilex. The antioxidative activity, which was previously investigated, was correlated with the α-tocopherol content. Correlation coefficients were 0.947 and 0.904 for extracts and leaves, respectively.     

Antioxidant activity of tea extracts in lipids and correlation with polyphenol content

The present study examined the antioxidative activity of water and ethanol extracts of green and black tea leaves against the oxidation of heated sunflower oil and lard. Oxidation was conducted at 110 °C in the Rancimat test. Total polyphenols and catechin contents in tea extracts were measured. The research showed that the total polyphenol content in green and black tea leaves was 205.2 and 148.7 mg/g, respectively. In tea leaves extracts, it ranged between 245.9 mg/g and 837.7 mg/g and depended on the extraction solvent and the kind of tea used (p <0.001). The highest polyphenol content was observed in samples extracted with 95% ethanol, lower contents were found with the use of water. Results showed that the highest antioxidant activity, measured as an induction period, with 1000 ppm green tea ethanol extract, was comparable to á‐tocopherol activity in sunflower oil. In lard, the longest induction period was measured with 500 and 1000 ppm of green tea ethanol extract. Other tea extract concentrations were significantly less active. Statistical analysis of the tea extract antioxidant activity in lipids in the Rancimat test showed an essential influence of the catechin contents. Further statistical analysis also showed an influence of (?)‐epicatechin gallate (ECG), (?)‐epicatechin (EC), and (+)‐catechin (C) contents in the tea extracts on the antioxidant activity in lipids. It was stated that the antioxidant activity was higher in tea extracts containing high levels of ECG, EC, and C.     

Antioxidant capacity of flaxseed lignans in two model systems

The flaxseed lignans secoisolariciresinol (SECO) and its diglucoside secoisolariciresinol diglucoside (SDG) are reported to have a number of health benefits associated with their consumption that have in part been attributed to their antioxidant properties. In this study the relative antioxidant capacity of the flaxseed lignans vs. BHT was determined in two model systems. First, an antioxidants stoichiometric value was determined for SECO and SDG in a liposomal system as a mimic of lipid peroxidation. Stoichiometric values for SECO (1.5) and SDG (1.2) vs. BHT (2.0) were measured from the lag time for the formation of conjugated dienes; all values were significantly different (P<0.01). Second, the ability of flaxseed lignans to prevent oxidative degradation of canola oil was determined. Samples were stored at room temperature and analyzed at 30-d intervals over 120 d using a Rancimat^™ analyzer. The lignans prevented degradation of canola oil, as measured by induction time, in a concentration-dependent manner. Although SECO demonstrated a trend for better protection than either SDG or polymer containing SDG, they were not significantly different (P>0.01). There was also no significant difference between SECO or SDG and BHT, suggesting flaxseed lignans may be good alternatives to minimize rancidity in oil-based food products.     

Identification and phytotoxic activity of compounds produced during decomposition of corn and rye residues in soil

Residues from corn and rye plants were allowed to decompose in soil for periods up to 30 days at 22–23 °C, and the identity of some of the compounds produced as well as their relative phytotoxicity to lettuce seed and seedlings were determined. Paper, thin-layer, and gas chromatography were the principal methods used to identify the various compounds formed. The identities were confirmed by comparison with known synthetic compounds. Eighteen compounds were identified in the decomposing corn residues. Of these, salicylaldehyde, and butyric, phenylacetic, and 4-phenylbutyric acids were volatile, and benzoic,p-hydroxybenzoic, vanillic, ferulic,o-coumaric,o-hydroxyphenylacetic, salicylic, syringic,p-coumaric,trans-cinnamic, and caffeic acids were not volatile. Resorcinol,p-hydroxybenzaldehyde, and phloroglucinol were also found. In the decomposing rye residues, nine compounds were identified, including vanillic, ferulic, phenylacetic, 4-phenylbutyric,p-coumaric,p-hydroxybenzoic, salicylic, ando-coumaric acids, and salicylaldehyde. In the lettuce seed bioassay, most of the above compounds from corn and rye decomposition products exhibited some phytotoxicity. Phenylacetic, 4-phenylbutyric, salicylic, benzoic, ando-hydroxyphenylacetic acids were highly inhibitory to the growth of lettuce at concentrations between 25 and 50 ppm. The others reduced growth significantly at 100 ppm. Most of the phototoxic spots were located in theR _f 0.37–0.97 zone when developed in 2% acetic acid solvent.This study was supported in part by National Research Council of Canada Grant No. A2384 to Z.A. Patrick.     

Antioxidant activity of amino acid sodium and potassium salts in vegetable oils at frying temperatures

Previous studies reported that several amino acids had strong antioxidant activity in vegetable oils under frying conditions. In this study, amino acids were converted to their sodium or potassium salts, and a heating study was conducted with 5.5 mM amino acid salts in soybean oil (SBO) at 180°C. Sodium salts of amino acids including alanine, phenylalanine, and proline and disodium glutamate had significantly stronger antioxidant activity than the corresponding amino acids, and potassium salts had stronger antioxidant activity than sodium salts. Potassium salts of alanine and phenylalanine more effectively retained tocopherols in SBO than the corresponding amino acids during heating. Phenylalanine potassium salt had stronger antioxidant activity than phenylalanine in other vegetable oils including olive, high oleic soybean, canola, avocado, and corn oils. Phenylalanine potassium salt at 5.5 mM more effectively prevented oil oxidation than tert-butyl hydroquinone, a synthetic antioxidant, at its legal concentration limit (0.02%) indicating its feasibility as a new antioxidant for frying.     

Antioxidant activity of pine bark procyanidins in bulk corn oil and corn oil‐in‐water emulsions

In this work, the ability of pine bark procyanidins to hinder oxidation in bulk corn oil and corn oil‐in‐water‐emulsion has been investigated. A preliminary characterisation of the obtained aqueous (AF) and organic (OW) fractions and subfractions suggested a very polar character and showed that both fractions possess remarkable antioxidant activity when minimum concentrations of 2 mg/mL are used. OW fractions and subfractions derived from both pine varieties were able to inhibit oxidation in oils. More specifically, two organic subfractions were the most efficient for retarding the degradation process, with levels of 62% and 50% after 8 days of treatment, respectively. Organic subfractions obtained from both varieties of pine also rendered possible inhibition levels in oil‐in‐water‐emulsions up to 80% after 4 days of oxidation, more than 3 times higher than the levels provided by tocopherol, a well‐known model commercial antioxidant, which confirms the excellent antioxidant potential of procyanidins from pine bark. Practical application: Lipid deterioration leads to losses in quality and nutritional value and to the development of off‐flavours in many foodstuffs. One way to overcome this drawback is by using antioxidants of natural origin, which is a subject of a great scientific and industrial interest, reflected by the growing number of papers and patents published during the last years. Since aqueous and organic fractions obtained from Pinus pinaster and Pinus radiata bark turned out to be an adequate source of procyanidins in previous investigations of our group, their possible antioxidant role in model lipid systems was investigated. This approach entails also another benefit in terms of waste valorisation, since pine bark is a typical residue of agroforestal industries.     

Conifer seed oils: Distribution of Δ5 acids between α and β chains by13C nuclear magnetic resonance spectroscopy

Nine seed oils from three different conifer families, already examined by gas chromatography and known to contain diene, triene, and tetraene C₁₈ and C₂₀Δ5 acids, have been reexamined by high-resolution¹³C nuclear magnetic resonance spectroscopy. The Δ5 acids are apparent only in the α-chains. This location is independent of chainlength, double-bond number, and the species considered and is probably a general factor of conifer seed oils. The spectra confirm the presence of oleic, linoleic, α-linolenic, and of Δ5 acids and give quantitative information about (total) n-6, n-3, and Δ5 acids that is in accord with that obtained by gas chromatography.     

Activity of antioxidants in solution and in irradiated heterogeneous system

The efficiency of some common antioxidants, α-tocopherol, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), was studied relative to β-carotene in a homogeneous solution and in a model system of an irradiated solid food. Relative reactivities in homogeneous solution covered a range of three orders of magnitude, α-tocopherol being the best and BHT the poorest antioxidant of the three. In irradiated systems consisting of oleic acid coated on a solid support (egg white), the range of reactivities was much narrower within one order of magnitude. In solution, there was a parallelism of the relative reactivities with oxidizing alkoxyl radicals derived from oleic acid hydroperoxides andtert-butyl hydroperoxide. On the solid support the relative reactivities of α-tocopherol and BHA with oleic acid radiation-induced oxidizing radicals were reversed, BHA appearing the best. Efficient antioxidants do not retain their great antioxidant activity in comparison with the moderate ones on transition from a homogeneous solution to a heterogeneous system. Relative efficiencies of antioxidants do not critically depend on the nature of oxidizing radicals in heterogeneous media.     

Genotype and growing location effects on phytosterols in canola oil

There is little information available about phytosterols in canola (Brassica napa L.) oil and the effects of genotype and growing locations from Virginia and the mid-Atlantic region of the United States, a potential area for the establishment of domestic production to provide edible oil. Our objectives were to characterize the phytosterols, phospholipids, unsaponifiable matter, and FA in oil from Virginia-grown canola. Among 11 canola genotypes grown at two locations during 1995–1996 significant variations existed for oil content and FA profiles, but not for contents of phospholipids, unsaponifiable matter, total phytosterols, campesterol, stigmasterol, and β-sitosterol, Total phytosterol content in the oil of Virginia-grown canola varied from 0.7 to 0.9% with a mean of 0.8%. This concentration compared favorably with oil from Canadian canola, which typically contains 0.5 to 1.1% total phytosterols. The mean contents of brassicasterol, campesterol, stigmasterol, β-sitosterol, Δ⁵-avenasterol, and Δ⁷-stigmatenol as percentages of total phytosterols in Virginia-grown canola were: 9.7, 32.0, 0.6, 49.3, 4.99, and 3.5%, respectively. Growing location did not affect phytosterols in Virginia-grown canola oil but had significant effects on contents of phospholipids, and saturated (myristic, stearic, and arachidic) and unsaturated (palmitoleic, linoleic, linolenic, eicosenoic, and erucic) FA.     

Changes in the Phytochemical Profile and Antioxidant Properties of Prunus persica Fruits after the Application of a Commercial Biostimulant Based on Seaweed and Yeast Extract

Plant biostimulants are formulations that are experiencing great success from the perspective of sustainable agriculture. In this work, we evaluated the effect derived from the application of a biostimulant based on algae and yeast extracts (Expando^®) on the agronomic yield and nutraceutical profile of two different cultivars (“Sugar Time” and “West Rose”) of Prunus persica (peach). Although, at the agronomic level, significant effects on production yields were not recorded, the biostimulant was able to reduce the ripening time, increase the fruit size, and make the number of harvestable fruits homogeneous. From a nutraceutical point of view, our determinations via spectrophotometric (UV/Vis) and chromatographic (HPLC-DAD-MS/MS) analysis showed that the biostimulant was able to boost the content of bioactive compounds in both the pulp (5.0 L/ha: +17%; 4.0 L/ha: +12%; 2.5 L/ha: +11%) and skin (4.0 L/ha: +38%; 2.5 L/ha: +15%). These changes seem to follow a dose-dependent effect, also producing attractive effects on the antioxidant properties of the fruits harvested from the treated trees. In conclusion, the biostimulant investigated in this work proved to be able to produce more marketable fruit in a shorter time, both from a pomological and a functional point of view.     

Antioxidant Activity Evaluation of Tocored through Chemical Assays,Evaluation in Stripped Corn Oil,and CAA Assay

γ‐Tocopherol‐5,6‐quinone (tocored) is a crucial oxidized product of γ‐tocopherol (γ‐T) found in edible oil. Previously published studies on antioxidant activity (AOA) of tocored are not consistent. This study aims to monitor its AOA comprehensively through chemical assays (1,1‐diphenyl‐2‐picrylhydrazyl [DPPH] and ferric reducing antioxidant power [FRAP]), antioxidant evaluation in a food model system (stripped corn oil), and cellular antioxidant activity (CAA) assay, which would reasonably widen the knowledge of the AOA of γ‐T and tocored. In both DPPH and FRAP assays, tocored shows less AOA than γ‐T. Results of chemical properties in the Schaal oven test show that tocored possesses better AOA than γ‐T. Correlation coefficients of γ‐T and tocored between peroxide and K₂₃₄ or p‐AnV are 0.8784–0.9875 and 0.8716–0.9879, respectively. The CAA assay also shows that tocored possesses better cellar AOA than γ‐T, with an EC₅₀ at 21.55 µg mL^?1. Drawing conclusions from the results from chemical assays, evaluation in stripped corn oil, and CAA assay, tocored is verified as a potent antioxidant in edible vegetable oils compared to γ‐T. Practical Applications: The present work widens the knowledge of antioxidant activity of tocored and gamma‐tocopherol, and contributes to the understanding of existing antioxidant activity when gamma tocopherol is depleted when edible oils are in storage and processing processes.     

Clinical application of C18 and C20 chain length polyunsaturated fatty acids and their biotechnological production in plants

A potential revolution in FA therapies is on the horizon. In recent years, the full magnitude of various FA treatments and their overall importance to health has become increasingly apparent. Fetal and infant nutrition studies have clearly shown that FA status at birth can have life-long health implications affecting eye and brain function, insulin resistance, and blood pressure control. As well, nutrition studies have identified dietary imbalances and deficiencies that have the potential to alter the health of future generations severely and to promote progression of age-related degenerative disorders. Mixtures of naturally occurring FA have shown promise as therapeutic agents for a diverse range of health conditions including atopic eczema, rheumatoid arthritis, cardiovascular disease, and neurological problems. Through the 1990s, the creation of technologies to concentrate and formulate pharmacologically active individual FA components as well as tailored combinations propelled development of this new drug category. However, high production costs and government regulatory encumbrance limited the expansion of this emerging pharmaceutical sector. Fortunately, many countries are now creating regulatory frameworks that are better suited for product evaluation and control of the manufacturing FA products than historical drug models, and hence expansion in this area is now anticipated.     

Phenolic acid content of soils from wheat-no till,wheat-conventional till,and fallow-conventional till soybean cropping systems

Soil core (0–2.5 and/or 0–10 cm) samples were taken from wheat no till, wheat-conventional till, and fallow-conventional till soybean cropping systems from July to October of 1989 and extracted with water in an autoclave. The soil extracts were analyzed for seven common phenolic acids (p-coumaric, vanillic,p-hydroxybenzoic, syringic, caffeic, ferulic, and sinapic; in order of importance) by high-performance liquid chromatography. The highest concentration observed was 4 g/g soil forp-coumaric acid. Folin & Ciocalteu's phenol reagent was used to determine total phenolic acid content. Total phenolic acid content of 0- to 2.5-cm core samples was approximately 34% higher than that of the 0- to 10-cm core samples. Phenolic acid content of 0- to 2.5-cm core samples from wheat-no till systems was significantly higher than those from all other cropping systems. Individual phenolic acids and total phenolic acid content of soils were highly correlated. The last two observations were confirmed by principal component analysis. The concentrations were confirmed by principal component analysis, tions of individual phenolic acids extracted from soil samples were related to soil pH, water content of soil samples, total soil carbon, and total soil nitrogen. Indirect evidence suggested that phenolic acids recovered by the water-autoclave procedure used came primarily from bound forms in the soil samples.The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of products named, nor criticism of similar ones not mentioned.     

Divergence in Structure and Activity of Phenolic Defenses in Young Leaves of Two Co-Occurring <Emphasis Type="Italic">Inga</Emphasis> Species

The leaves of tropical forest trees are most likely to suffer herbivore damage during the period of expansion. Herbivore selection on young leaves has given rise to a variety of leaf developmental strategies and age-specific chemical defense modes. We are studying correlations between leaf developmental types and chemical defenses in the Neotropical genus Inga. We have characterized defense metabolites in Inga goldmanii and Inga umbellifera, two species that co-occur in the lowland moist forest of Panama. These congeners have markedly different young-leaf developmental phenotypes but suffer approximately equal rates of herbivory. Bioassays of whole and fractionated leaf extracts using larvae of Heliothis virescens show that I. goldmanii chemical defenses are nearly three times more inhibitory than those of I. umbellifera. In both species, most of the inhibitory activity resides in complex mixtures of monomeric and polymeric flavan-3-ols. This group comprises >30% of young leaf dry weight in both I. goldmanii and I. umbellifera. The species’ phenolic chemistry differs markedly, however, both in the structure of the monomeric units and in the distribution of polymer sizes. The differences in chemical structure have pronounced effects on their bioactivities, with I. goldmanii flavans being twice as inhibitory to H. virescens larvae as I. umbellifera flavans, and more than three times more efficient at protein binding. Given the extraordinarily high polyphenol concentrations that are found in the young leaves of these species, protein precipitation could be an important mechanism of growth inhibition. Nevertheless, our data show that another mode of phenolic action, possibly oxidative stress, occurs simultaneously.     

Allelopathic activity in wheat-conventional and wheat-no-till soils: Development of soil extract bioassays

The primary objective of this research was to determine if soil extracts could be used directly in bioassays for the detection of allelopathic activity. Here we describe: (1) a way to estimate levels of allelopathic compounds in soil; (2) how pH, solute potential, and/or ion content of extracts may modify the action of allelopathic compounds on germination and radicle and hypocotyl length of crimson clover (Trifolium incarnatum L.) and ivyleaved morning glory (Ipomoea hederacea L. Jacquin.); and (3) how biological activity of soil extracts may be determined. A water-autoclave extraction procedure was chosen over the immediate-water and 5-hr EDTA extraction procedures, because the autoclave procedure was effective in extracting solution and reversibly bound ferulic acid as well as phenolic acids from wheat debris. The resulting soil extracts were used directly in germination bioassays. A mixture of phenolic acids similar to that obtained from wheat-no-till soils did not affect germination of clover or morning glory and radicle and hypocotyl length of morning glory. The mixture did, however, reduce radicle and hypocotyl length of clover. Individual phenolic acids also did not inhibit germination, but did reduce radicle and hypocotyl length of both species. 6-MBOA (6-methoxy-2,3-benzoxazolinone), a conversion product of 2-o-glucosyl-7-methoxy-1,4-benzoxazin-3-one, a hydroxamic acid in living wheat plants, inhibited germination and radicle and hypocotyl length of clover and morning glory. 6-MBOA, however, was not detected in wheat debris, stubble, or soil extracts. Total phenolic acids (FC) in extracts were determined with Folin and Ciocalteu's phenol reagent. Levels of FC in wheat-conventionaltill soil extracts were not related to germination or radicle and hypocotyl length of either species. Levels of FC in wheat-no-till soil extracts were also not related to germination of clover or morning glory, but were inversely related to radicle and hypocotyl length of clover and morning glory. FC values, solute potential, and acidity of wheat-no-till soil extracts appeared to be independent (additive) in action on clover radicle and hypocotyl length. Radicle and hypocotyl length of clover was inversely related to increasing FC and solute potential and directly related to decreasing acidity. Biological activity of extracts was determined best from slopes of radicle and hypocotyl length obtained from bioassays of extract dilutions. Thus, data derived from the water-autoclave extraction procedure, FC analysis, and slope analysis for extract activity in conjunction with data on extract pH and solute potential can be used to estimate allelopathic activity of wheat-no-till soilsThe use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of products named, or criticism of similar ones not mentioned.     

Phenolic Compounds and Antioxidant Capacity of Monovarietal Olive Oils Produced in Argentina

Virgin olive oil has high levels of phenolic compounds that are highly bioavailable; these compounds are receiving considerable attention for their antioxidant activity, closely related to the prevention of non‐communicable chronic diseases. The aim of this work was to characterize the phenolic profile and antioxidant capacity of monovarietal olive oils cvs. Arauco, Arbequina, Farga and Empeltre produced in Argentina. This study focused on the relationship between the single molecules or classes of molecules quantified by SPE‐CZE, the corresponding Folin‐Ciocalteu results, and antioxidant capacity using three different tests. Fifteen compounds were simultaneously determined: tyrosol, vinylphenol, oleuropein, hydroxytyrosol, rutin, catechin, naringenin, cinnamic acid, chlorogenic acid, syringic acid, luteolin, apigenin, vanillin acid, quercetin, and caffeic acid. The phenolic contents of the monovarietal olive oils show significant differences between different varieties (p < 0.05), with positive and significant Pearson's correlation found between Folin–Ciocalteu and CZE. Besides, the correlation between the content of total polyphenols and antioxidant capacity was high for all the antioxidant assays performed. When analyzing the correlation coefficients of the different families of phenolic compounds studied, simple phenols and cinnamic acid derivatives show a higher correlation with antioxidant capacity. Thus, findings obtained in this study demonstrated that Arauco olive oil, autochthonous for Argentina, possesses the highest antioxidant/free‐radical scavenging properties, which are very likely due to the presence of high contents of phenolic compounds.     

Alteration of steryl ester content and positional distribution of fatty acids in triacylglycerols by chemical and enzymatic interesterification of plant oils

Steryl ester content of refined and interesterified corn, soybean, and rapeseed oils has been measured via clean-up on a short silica gel column, followed by high performance liquid chromatography with evaporative light-scattering mass detector. Chemical interesterification, catalyzed by sodium methoxide, led to random positional distribution of fatty acids in triacylglycerols and some increase in the steryl ester content of all three oils. Enzymatic interesterification, catalyzed by the immobilized lipase from Rhizomucor miehei (Lipozyme), resulted in a distinct reduction in steryl ester content, but essentially no alteration in positional distribution of fatty acids in triacylglycerols occurred. Formation of steryl esters during chemical and enzymatic interesterification was also examined by radioactive tracer technique with [4-¹⁴C]β-sitosterol added as marker to refined rapeseed oil and measurement of the radioactive steryl esters formed. Chemical interesterification of rapeseed oil resulted in moderate formation (10% of total radioactivity) of radioactive β-sitosteryl esters. Enzymatic interesterification of the oil, catalyzed by Lipozyme, led to little formation of radioactive β-sitosteryl esters, whereas with the lipase from Candida cylindracea high proportions (>90% of total radioactivity) of ¹⁴C-labeled β-sitosteryl esters were formed. Part of doctoral thesis of Roseli Ap. Ferrari to be submitted to Faculdade de Engenharia de Alimentos, Universidade de Campinas, Campinas, Brazil.