Antioxidant effects of extracts from Cassia tora L. prepared under different degrees of roasting on the oxidative damage to biomolecules

The effects of water extracts from Cassia tora L. (WECT) treated with different degrees of roasting (unroasted and roasted at 150, 200, and 250 degrees C) on the oxidative damage to deoxyribose, DNA, and DNA base in vitro were investigated. It was found that WECT alone induced a slight strand breaking of DNA. In the presence of Fe(3+)/H(2)O(2), WECT accelerated the strand breaking of DNA at a concentration of 2 microg/mL; however, it decreased with increasing concentrations (>5 microg/mL) of WECT. WECT also accelerated the oxidation of deoxyribose induced by Fe(3+)-EDTA/H(2)O(2) at a concentration of 0.2 mg/mL but inhibited the oxidation of deoxyribose induced by Fe(3+)-EDTA/H(2)O(2)/ascorbic acid. Furthermore, WECT accelerated the oxidation of 2'-deoxyguanosine (2'-dG) to form 8-OH-2'-dG induced by Fe(3+)-EDTA/H(2)O(2). The prooxidant action of WECT on the oxidation of 2'-dG was in the order of unroasted > roasted at 150 degrees C > roasted at 200 degrees C > roasted at 250 degrees C. The decrease in the prooxidant activity of the roasted sample might be due to the reduction in its anthraquinone glycoside content or the formation of antioxidant Maillard reaction products after roasting. Thus, WECT exhibited either a prooxidant or an antioxidant property in the model system that was dependent on the activities of the reducing metal ions, scavenging hydroxyl radical, and chelating ferrous ion.     

Inhibitory effects of Cassia tora L. on benzo[a]pyrene-mediated DNA damage toward HepG2 cells

The effects of water extracts from Cassia tora L. (WECT) treated with different degrees of roasting on benzo[a]pyrene (B[a]P)-induced DNA damage in human hepatoma cell line HepG2 were investigated via the comet assay without exogenous activation mixtures, such as S9 mix. WECT alone, at concentrations of 0.1-2 mg/mL, showed neither cytotoxic nor genotoxic effect toward HepG2 cells. B[a]P-induced DNA damage in HepG2 cells could be reduced by WECT in a dose-dependent manner (P < 0.05). At a concentration of 1 mg/mL, the inhibitory effects of WECT on DNA damage were in the order unroasted (72%) > roasted at 150 degrees C (60%) > roasted at 250 degrees C (23%). Ethoxyresorufin-O-dealkylase activity of HepG2 cells was effectively inhibited by WECT, and a similar trend of inhibition was observed in the order unroasted (64%) > roasted at 150 degrees C (42%) > roasted at 250 degrees C (18%). The activity of NADPH cytochrome P-450 reductase was also decreased by unroasted and 150 degrees C-roasted samples (50% and 38%, respectively). Furthermore, glutathione S-transferase activity was increased by treatment with unroasted (1.26-fold) and 150 degrees C-roasted (1.35-fold) samples at 1 mg/mL. In addition, the contents of anthraquinones (AQs) in WECT, including chrysophanol, emodin, and rhein, were decreased with increasing roasting temperature. Each of these AQs also demonstrated significant antigenotoxic activity in the comet assay. The inhibitory effects of chrysophanol, emodin, and rhein on B[a]P-mediated DNA damage in HepG2 cells were 78, 86, and 71%, respectively, at 100 microM. These findings suggested that the decreased antigenotoxicity of the roasted samples might be due to a reduction in their AQs content.     

Antioxidant effects of water extracts from barley (Hordeum vulgare L.) prepared under different roasting temperatures

The antioxidant effects of water extracts of roasted barley (WERB) were investigated under different roasting temperatures and compared with those of the water extracts of unroasted barley (WEUB). It was found that the Maillard reaction products increased upon increasing the roasting temperatures. Both WERB and WEUB exhibited significant antioxidant activities in linoleic acid and liposome model systems. Although WERB and WEUB afforded considerable protection against the damage of deoxyribose and proteins, the antioxidant efficiency of roasted samples was weaker than that of unroasted samples because of the reduction of antioxidant components (catechin, tocopherol, and lutein) with increasing roasting temperature. Unroasted samples were more effective in reducing power, quenching free radical, hydroxyl radical, and chelating iron than the roasted samples. The different antioxidant activity among roasted and unroasted barley samples may be partly attributed to the changes in catechin, tocopherol, and lutein contents.     

Antioxidant activity of extracts of black sesame seed (Sesamum indicum L.) by supercritical carbon dioxide extraction

Antioxidant activities of extracts derived from sesame seed by supercritical carbon dioxide (SC-CO(2)) extraction and by n-hexane were determined using alpha,alpha-diphenyl-beta-picylhydrazyl (DPPH) radical scavenging and linoleic acid system methods. The highest extracted yield was given at 35 degrees C, 40 MPa, and a CO(2) flow rate of 2.5 mL min(-1) by an orthogonal experiment. The yields of extracts increased with increasing pressure, and yields at 40 and 30 MPa were higher than that by solvent extraction at 46.50%. Results from the linoleic acid system showed that the antioxidant activity follows the order: extract at 35 degrees C, 20 MPa > BHT > extract at 55 degrees C, 40 MPa > extract at 55 degrees C, 30 MPa > Trolox > solvent extraction > alpha-tocopherol. The SC-CO(2) extracts exhibited significantly higher antioxidant activities comparable to that by n-hexane extraction. The extracts at 30 MPa presented the highest antioxidant activities assessed in the DPPH method. At 20 MPa, the EC(50) increased with temperature, which indicated that the antioxidant activity was decreased in a temperature-dependent manner. The significant differences of antioxidant activities were found between the extracts by SC-CO(2) extraction and n-hexane. However, no significant differences were exhibited among the extracts by SC-CO(2) extraction. The vitamin E concentrations were also significantly higher in SC-CO(2) extracts than in n-hexane extracts, and its concentrations in extracts corresponded with the antioxidant activity of extracts.     

Antioxidant properties of roasted coffee residues

The antioxidant activity of roasted coffee residues was evaluated. Extraction with four solvents (water, methanol, ethanol, and n-hexane) showed that water extracts of roasted coffee residues (WERCR) produced higher yields and gave better protection for lipid peroxidation. WERCR showed a remarkable protective effect on oxidative damage of protein. In addition, WERCR showed scavenging of free radicals as well as the reducing ability and to bind ferrous ions, indicating that WERCR acts as both primary and secondary antioxidants. The HPLC analyses showed that phenolic acids (chlorogenic acid and caffeic acid) and nonphenolic compounds [caffeine, trigonelline, nicotinic acid, and 5-(hydroxymethyl)furfuraldehyde] remained in roasted coffee residues. These compounds showed a protective effect on a liposome model system. The concentrations of flavonoids and polyphenolic compounds in roasted coffee residues were 8,400 and 20,400 ppm, respectively. In addition, the Maillard reaction products (MRPs) remaining in roasted coffee residues were believed to show antioxidant activity. These data indicate that roasted coffee residues have excellent potential for use as a natural antioxidant source because the antioxidant compounds remained in roasted coffee residues.     

Isolation of an in vitro and ex vivo antiradical melanoidin from roasted barley

The antiradical properties of water-soluble components of both natural and roasted barley were determined in vitro, by means of DPPH* assay and the linoleic acid-beta-carotene system, and ex vivo, in rat liver hepatocyte microsomes against lipid peroxidation induced by CCl4. The results show the occurrence in natural barley of weak antioxidant components. These are able to react against low reactive peroxyl radicals, but offer little protection against stable DPPH radicals deriving from peroxidation in microsomal lipids. Conversely, roasted barley yielded strong antioxidant components that are able to efficiently scavenge free radicals in any system used. The results show that the barley grain roasting process induces the formation of soluble Maillard reaction products with powerful antiradical activity. From roasted barley solution (barley coffee) was isolated a brown high molecular mass melanoidinic component, resistant to acidic hydrolysis, that is responsible for most of the barley coffee antioxidant activity in the biosystem.     

Evaluation of antioxidant potential of aloe vera (Aloe barbadensis miller) extracts

The polysaccharide and flavonoid concentrations of two-, three-, and four-year-old Aloe vera were determined, and their antioxidant activities were evaluated compared to BHT and alpha-tocopherol by the DPPH radical scavenging method and the linoleic acid system at 100 microg of soluble solids per mL of ethanol. The results showed that three-year-old Aloe vera contained significantly higher levels of polysaccharides and flavonoids than two- and four-year-old Aloe vera, and no significant differences in flavonoid levels were found between three- and four-year-old Aloe vera. All the aloe extracts showed significant antioxidant activity. The antioxidant activity of Aloe vera extracts and reference compounds followed the order: three-year-old Aloe vera > BHT > four-year-old Aloe vera > alpha-tocopherol > two-year-old Aloe vera. The three-year-old extract exhibited the strongest radical scavenging activity of 72.19%, which is significantly higher than that of BHT at 70.52% and alpha-tocopherol at 65.20%. These data suggest that the growth stage plays a vital role in the composition and antioxidant activity of Aloe vera.     

Effects of roasting on pyrazine contents and oxidative stability of red pepper seed oil prior to its extraction

Red pepper seeds were roasted with constant stirring for 6, 9, 10, and 12 min at 210 degrees C, and oils were extracted from the roasted red pepper seeds using an expeller. The iodine values and fatty acid compositions of red pepper seed oils did not change with roasting time. The fatty acid composition of the oil obtained from the red pepper seeds roasted for 6 min was 0.24% myristic acid, 13. 42% palmitic acid, 0.33% palmitoleic acid, 2.07% stearic acid, 10. 18% oleic acid, 73.89% linoleic acid, and 0.37% linolenic acid, showing a fatty acid composition similar to that of high-linoleate safflower oil. Thirteen alkylpyrazines were identified in the roasted red pepper seed oils: 2-methylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-5-methylpyrazine, trimethylpyrazine, 2,6-diethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, tetramethylpyrazine, 2, 3-diethyl-5-methylpyrazine, 2-isobutyl-3-methylpyrazine, and 3, 5-diethyl 2-methylpyrazine. The pyrazine content increased markedly as the roasting time increased, showing 2.63, 5.01, 8.48, and 13.10 mg of total pyrazine/100 g of oils from the red pepper seeds roasted for 6, 8, 10, and 12 min, respectively, at 210 degrees C. 2, 5-Dimethylpyrazine in the roasted red pepper seed oil seemed to be the component most responsible for the pleasant nutty aroma of the oils. The oxidative stabilities of oils increased greatly as the roasting time increased.     

Effects of roasting on hazelnut lipids

The effect of roasting on some nutritional characteristics of hazelnut lipidic fraction was investigated. Hazelnuts (Corylus avellana L.) were submitted to several different thermal treatments, comprising different temperatures (125-200 degrees C) and times of exposure (5, 15, and 30 min) and analyzed for their moisture and crude fat. Raw and roasted hazelnuts were also analyzed for their compositions in phytosterols and fatty acids (including trans isomers) by GC-FID, triacylglycerols by HPLC-ELSD, and tocopherols and tocotrienols by HPLC-DAD/fluorescence spectroscopy. Minor changes occurred in the fatty acid and triacylglycerol compositions. As temperatures and roasting periods increased, generally, a modest increase of oleic and saturated fatty acids and a decrease of linoleic acid, expressed as relative percentages, occurred. Similarly, an increase of triacylglycerols containing oleic acid moieties and a decrease of those containing linoleic acid moieties were found in the roasted samples. Roasting caused a modest decrease of the beneficial phytosterols (maximum 14.4%) and vitamin E homologues (maximum 10.0%) and a negligible increase of the trans fatty acids.     

Effect of selenium on increasing the antioxidant activity of tea leaves harvested during the early spring tea producing season

This research was to determine the effect of foliar application of selenium on increasing the antioxidant activity of tea harvested during the early spring tea producing season using a alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical scavenging method and the linoleic acid system. The results showed that the radical scavenging ability of the tea extracts followed this order during the first 60 min: selenium-enriched tea obtained by fertilization with selenate > BHT > selenium-enriched tea obtained by fertilization with selenite > alpha-tocopherol > regular tea. Se-enriched tea obtained by fertilization with selenate exhibited the highest inhibition percentage of 84.29% at 30 min. Se-enriched tea extracts provided higher hydrogen-donating capabilities than regular tea and contrasts with BHT and alpha-tocopherol at the concentration of 100 microg of solids/mL of ethanol. There was a little change in the sequence of radical scavenging ability during the later 60 min: Se-enriched tea obtained by fertilization with selenate > Se-enriched tea obtained by fertilization with selenite > BHT > regular tea > alpha-tocopherol. The individual activity of tea extracts and references measured by the linoleic acid system showed that the tea extracts, BHT, and alpha-tocopherol manifested almost the same patterns of activity as the DPPH method. Tea enriched in selenium by fertilization with selenate still exhibited the highest inhibition activity of lipid oxidation, whereas alpha-tocopherol showed the lowest inhibition. The antioxidant activity of Se-enriched green tea harvested during the early spring tea producing season is enhanced compared to regular tea.     

Antioxidant activity of indigenous edible mushrooms

The current study was undertaken to measure the antioxidant potential from water and methanolic extracts of fruiting bodies of 23 species of mushrooms naturally grown in different geographic locations of India. The antioxidant ability of each species was analyzed for the total antioxidative status, employing multimechanistic antioxidative assays such as inhibition of lipid peroxidation, determination of reducing power, and free radical scavenging ability, in addition to determination of total phenolics and identification of phenolic acids by HPLC analysis, because the phenolics are known to contribute largely to antioxidant potential. The antioxidant potential of these varieties of mushrooms was determined by summing the antioxidative activity (AOA) of each variety by varied antioxidant assays followed by determining the relative percent of AOA defined as the "antioxidant index" (AI). On the basis of the AI, the mushroom species were graded as very high, high, moderate, and low. Termitomyces heimii was identified as the best variety, which showed 100% AI with 37 mg of phenolics/g of sample, 418 units of reducing power ability (RPA)/g, and an IC50 of approximately 1.1 mg (dry weight)/mL, free radical scavenging activity (FRS) in the water extract followed by 11.2 mg of phenolics/g, 275 units of RPA/g, and an IC50 of approximately 2.7 mg (dry weight)/mL of FRS in the methanolic extract. Following T. heimii, Termitomyces mummiformis exhibited an AI of 86% within the "very high" group. Potent inhibitions of lipid peroxidation of approximately 100 and 69% was also observed in T. heimii and T. mummiformis, respectively. Water extracts ranged from 34 to 49% and methanolic extracts varied from 20 to 32% on dry weight of mushroom fruiting body. Total phenolic compounds were higher in the water extracts (2-37 mg/g) than in methanolic extract (0.7-11.2 mg/g). The AOA measured in the water extract was better than that from the methanolic extract. HPLC analysis of phenolic acids in the two mushroom species, namely, T. heimii and T. mummiformis, displaying maximum AOA potential indicated a preponderance of tannic acid, gallic acid, protocatacheuic acid, and gentisic acid. Studies thus provide the precise antioxidant status of 23 indigenous species of mushrooms, which can serve as a useful database for the selection of mushrooms for the function of preparation of mushroom-based nutraceutics.     

Influence of Roasting Temperature of Barley on the Powder Characteristics and Preparation of Tea

Roasting improves the palatability of barley grains. After processing, the resulting powder is widely used to elaborate beverages such as coffee and tea. The objective of this research was to evaluate the influence of roasting on the characteristics of barley grains and the derived powder. The kinetics of release of soluble solids during the powder hydration at 80°C, performed to produce beverages such as tea, was also determined. In addition, the influence of roasting and rehydration temperatures on the physical composition of the beverages and on the release of soluble solids was investigated. After roasting, barley was ground and sieved. The powder retained in the 0.425 mm sieve was used in the analyses. Owing to roasting, the average protein content of barley increased from 10.56 to 12.88 g/100 g, and the sugar content decreased from 730 to 12.99 mg/mL, which is ascribed to the high process temperature. The phenolic compounds increased from 105.33 to 253.07 mg of ferulic acid per milliliter between the nonprocessed sample and the one roasted at 240°C, respectively. The antioxidant activity decreased with the roasting temperature rise (160–240°C) from 11.60 to 5.30 μg of 2,2‐diphenyl‐1‐picrylhydrazyl per milliliter. In the production of beverages such as tea, higher roasting temperatures led to a greater release of soluble solids in water.     

Antioxidant activity of phenolic compounds isolated from Mesona procumbens Hemsl

The antioxidant activity of phenolic compounds isolated from Mesona procumbens Hemsl. (Hsian-tsao) was investigated. Hsian-tsao was extracted with various solvents, and the results showed that the fraction treated with acidic ethyl acetate (pH 2) possessed large amounts of phenolic compounds and a strong antioxidant activity on peroxidation of linoleic acid. The antioxidant activity (inhibition of peroxidation, IP%) of the acidic ethyl acetate of Hsian-tsao extract at 50 microg/mL (98.9%) was stronger than those of 50 microg/mL alpha-tocopherol (78%) and BHA at 10 microg/mL (90%). When fractionated with Amberlite XAD-7 gel chromatography, the acidic ethyl acetate fraction of Hsian-tsao extract was separated into four subfractions (A-D). Subfraction B, with high yield and strong antioxidant activity, was further isolated and purified and then identified as containing protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, and syringic acid by means of UV, EI-MS, and (1)H and (13)C NMR. The antioxidant capability of isolated compounds was also determined using the thiocyanate system and the erythrocyte ghost system. The results indicate that the phenolic acids could be important antioxidant components in Hsian-tsao, among which caffeic acid with the highest antioxidant activity and the greatest content is most important.     

Changes in the concentrations of acrylamide, selected odorants, and catechins caused by roasting of green tea

This research aims to optimize roasted green tea (Houjicha) processing by using roasting treatments to achieve acrylamide mitigation without compromising the quality. 2-Ethyl-3,5-dimethylpyrazine and 2-ethyl-3,6-dimethylpyrazine were identified as potent odorants by aroma extract dilution analysis. In preliminary sensory experiments, the desirable Houjicha flavor was produced in products roasted at 160 degrees C for 30 min and at 180 degrees C for 15 min. Under these conditions, potent odorants were formed at levels adequate for contributing to the Houjicha flavor. Acrylamide amounts in tea infusions were 2.0 and 4.0 microg/L by roasting at 160 degrees C for 30 min and at 180 degrees C for 15 min, respectively. Compared to roasting at 180 degrees C, the degradation of tea catechins was suppressed by roasting at 160 degrees C. Hence, roasting at 160 degrees C for is recommended for Houjicha processing for acrylamide mitigation, formation of potent odorants, and suppression of degradation of tea catechins.     

Antioxidant properties of several medicinal mushrooms

Three species of medicinal mushrooms are commercially available in Taiwan, namely, Ganoderma lucidum (Ling-chih), Ganoderma tsugae (Sung-shan-ling-chih), and Coriolus versicolor (Yun-chih). Methanolic extracts were prepared from these medicinal mushrooms and their antioxidant properties studied. At 0.6 mg/mL, G. lucidum, G. lucidum antler, and G. tsugae showed an excellent antioxidant activity (2.30-6.41% of lipid peroxidation), whereas C. versicolor showed only 58.56%. At 4 mg/mL, reducing powers were in the order G. tsugae (2.38) approximately G. lucidum antler (2.28) > G. lucidum (1.62) > C. versicolor (0.79). At 0.64 mg/mL, scavenging effects on the 1,1-diphenyl-2-picrylhydrazyl radical were 67.6-74.4% for Ganoderma and 24.6% for C. versicolor. The scavenging effect of methanolic extracts from G. lucidum and G. lucidum antler on hydroxyl radical was the highest (51.2 and 52.6%) at 16 mg/mL, respectively. At 2.4 mg/mL, chelating effects on ferrous ion were in the order G. lucidum antler (67.7%) > G. lucidum (55.5%) > G. tsugae (44.8%) > C. versicolor (13.2%). Total phenols were the major naturally occurring antioxidant components found in methanolic extracts from medicinal mushrooms. Overall, G. lucidum and G. tsugae were higher in antioxidant activity, reducing power, scavenging and chelating abilities, and total phenol content.     

Determination of antioxidant properties of aroma extracts from various beans

Aroma extracts from fresh soybeans, mung beans, kidney beans, and azuki beans were prepared using simultaneous steam distillation and solvent extraction (SDE) under mild conditions (55 degrees C and 95 mmHg). Extracts were examined for antioxidative activities in two different assays. The aroma extracts isolated from all beans inhibited the oxidation of hexanal for nearly one month at a level of 250 microL/mL. Mung bean and soybean extracts inhibited malonaldehyde (MA) formation from cod-liver oil by 86% and 88%, respectively, at the 250 microL/mL level. Azuki and kidney bean extracts inhibited MA formation from cod-liver oil by 76% and 53%, respectively, at the 250 microL/mL level. The antioxidative activities of mung bean and soybean extracts were comparable with that of the natural antioxidant, alpha-tocopherol (vitamin E).     

Changes in key aroma compounds of Criollo cocoa beans during roasting

Application of a comparative aroma extraction dilution analysis on unroasted and roasted Criollo cocoa beans revealed 42 aroma compounds in the flavor dilution (FD) factor range of 1-4096 for the unroasted and 4-8192 for the roasted cocoa beans. While the same compounds were present in the unroasted and roasted cocoa beans, respectively, these clearly differed in their intensity. For example, 2- and 3-methylbutanoic acid (rancid) and acetic acid (sour) showed the highest FD factors in the unroasted beans, while 3-methylbutanal (malty), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel-like), and 2- and 3-methylbutanoic acid (sweaty) were detected with the highest FD factors in the roasted seeds. Quantitation of 30 odorants by means of stable isotope dilution assays followed by a calculation of odor activity values (ratio of the concentration/odor threshold) revealed concentrations above the odor threshold for 22 compounds in the unroasted and 27 compounds in the roasted cocoa beans, respectively. In particular, a strong increase in the concentrations of the Strecker aldehydes 3-methylbutanal and phenylacetaldehyde as well as 4-hydroxy-2,5-dimethyl-3(2H)-furanone was measured, suggesting that these odorants should contribute most to the changes in the overall aroma after roasting. Various compounds contributing to the aroma of roasted cocoa beans, such as 3-methylbutanoic acid, ethyl 2-methylbutanoate, and 2-phenylethanol, were already present in unroasted, fermented cocoa beans and were not increased during roasting.     

Antioxidant and pro-oxidant activities of aqueous extracts and crude polyphenolic fractions of rooibos (Aspalathus linearis)

Unfermented rooibos tea is known to contain higher levels of total polyphenols and flavonoids than its fermented counterpart, making it the obvious choice for the preparation of flavonoid-enriched fractions. Evaluation of aqueous extracts and crude polyphenolic fractions of unfermented and fermented rooibos showed anti- and/or pro-oxidant activities, using a linoleic acid-Tween-buffer emulsion for lipid peroxidation and the deoxyribose degradation assay, based on a Fenton reaction model system containing FeCl3-EDTA and H2O2 for the generation of hydroxyl radicals. Except for the ethyl acetate fraction, with the highest total polyphenol (TP) content and offering the least protection presumably due to pro-oxidant activity, the inhibition of lipid peroxidation by the samples correlated moderately with their TP content in a linear relationship (r = 0.896, P < 0.01). Using the deoxyribose degradation assay, the pro-oxidant activity of the aqueous extracts and their crude polymeric fractions (0.1 mg/mL in the reaction mixture) was linear with respect to their dihydrochalcone (aspalathin and nothofagin) (r = 0.977, P = 0.023) and flavonoid (r = 0.971, P = 0.029) content. Pro-oxidant activity was demonstrated for pure aspalathin. Using the same assay, but with ascorbate added to regenerate Fe3+ to Fe2+, the aqueous extract and crude polymeric fraction of fermented rooibos displayed hydroxyl radical scavenging activity. Fermentation (i.e., oxidation) of rooibos decreased the pro-oxidant activity of aqueous extracts, which was contributed to a decrease in their dihydrochalcone content. The in vitro pro-oxidant activity displayed by flavonoid-enriched fractions of rooibos demonstrates that one must be aware of the potential adverse biological properties of potent antioxidant extracts utilized as dietary supplements.     

Determination of antioxidant potential of volatile extracts isolated from various herbs and spices

Antioxidant activities of volatile extracts isolated from thyme, basil, rosemary, chamomile, lavender, and cinnamon were evaluated by two independent assays: the aldehyde/carboxylic acid assay and the conjugated diene assay. The volatile extracts were prepared from dried herbs and spices using liquid-liquid continuous extraction following steam distillation under reduced pressure (55 degrees C and 95 mmHg). The antioxidant activities of the extracts decreased in the following order in both of the lipophilic assay systems: thyme > basil > rosemary > chamomile > lavender and cinnamon. Thyme and basil extracts inhibited the oxidation of hexanal for 40 days at the levels of 10 microg/mL and 50 microg/mL, respectively. The extracts of thyme and basil were effective in retarding methyl linoleate deterioration at 40 degrees C, with activity increasing with concentration in the range 10-200 microg/mL. At a concentration of 50 microg/mL, thyme extract was similar in antioxidant activity to BHT and alpha-tocopherol in the conjugated diene assay. The antioxidant potentials of the volatile extracts used in this study were accurately measured by the lipophilic systems, such as the aldehyde/carboxylic acid assay and the conjugated diene assay.     

Murta leaves (Ugni molinae Turcz) as a source of antioxidant polyphenols

Extracts from Murta leaves are used by Chilean natives for their benefits on health and cosmetic properties, which are mainly due to the presence of polyphenolic compounds. Extraction of such compounds is strongly influenced by several variables, the effects of which are studied in this work; the antioxidant power of the resulting extracts was measured by two different methods [2,2-diphenyl-1-picrylhydrazyl (DPPH) and thiobarbituric acid reactive substances (TBARS)]. On the whole, maximum values of polyphenolic yields and antiradical power (DPPH method) were attained at 50 degrees C (from 25 to 50 degrees C) and a solvent-to-solid ratio (v/w) of 15:1 (15:1-25:1). The solvents assayed were ethanol, methanol, and water. The highest polyphenolic yield values (2.6% expressed as gallic acid) were reached with methanol, whereas maximum EC50 was attained by the ethanol extract (0.121 mol gallic acid/mol DPPH). Contact time was shown to have only a slight influence in alcoholic extraction, while in water a remarkable effect of increasing contact times (30-90 min) was observed. Just water was the solvent that offered the best result when the antioxidant power was measured by the TBARS method. High-performance liquid chromatography-mass spectrometry analysis revealed the presence of polyphenols, basically flavonols and flavanols, sometimes glycosilated; myricetin and quercetin glycosides were detected in all extracts, whereas epicatechin was present in alcoholic extracts and gallic acid was only present in water.