Antioxidant properties of aqueous extracts from selected lamiaceae species grown in Turkey

Water-soluble extracts from black thyme (Thymbra spicata L.), savory (Satureja cuneifolia Ten.), Spanish oregano (Coridothymus capitatus (L.) Reichb. f.), sweet marjoram (Majorana hortensis Moench), Syrian oregano (Origanum syriacum L.), Toka oregano (Origanum minutiflorum O. Schwarz et P. H. Davis), and Turkish oregano (Origanum onites L.) were screened for antioxidant properties in a battery of six in vitro assays. Total phenol content and qualitative-quantitative compositional analyses were also carried out. The extracts demonstrated varying degrees of efficacy in each screen. The savory extract was the most effective at reducing iron(III), scavenging 1,1-diphenyl-2-picrylhydrazyl radicals, inhibiting ascorbate-iron(III)-catalyzed hydroxyl radical-mediated brain phospholipid peroxidation, and site-specific hydroxyl radical-mediated 2-deoxy-d-ribose degradation. The Syrian oregano extract was the most effective chelator of iron(II), while Spanish and Turkish oregano extracts were the most effective inhibitors of nonsite-specific hydroxyl radical-mediated 2-deoxy-d-ribose degradation. All the extracts contained Folin-Ciocalteu reagent-reactive substances, which was confirmed by the presence of polar phenolic analytes (i.e., hydroxybenzoates, hydroxycinnamates, and flavonoids).     

Antioxidant activity of ethanolic extracts from several asparagus cultivars

Three different methods (antiradical activity, inhibition of primary oxidation, and ferric reducing power) have been used to evaluate the antioxidant activity of eight different asparagus cultivars and byproducts: white and green asparagus from Alcalá del Río (Guadalquivir Valley, Seville) and American hybrids, native spears, and their byproducts from Huétor-Tájar (Vega de Granada). The correlation between antioxidant activity and total phenol content was studied. Six standards were also tested to validate the modified methods for antioxidant activity determination. Results obtained for antiradical capacity and reducing power were very similar, and a high correlation with phenols was found (R > or = 0.9 for both tests). Sample origin was an important factor, spears from Huétor-Tájar having higher values (ARC between 7 and 10 and P(R) of 0.25-0.33) than those from Alcalá del Río (ARC 0.6-2 and P(R) of 0.05-0.07). Significant differences were found between spears with the same origin, suggesting that genetics are another factor to take into account. Asparagus inhibits lipid primary oxidation, but no correlation between the inhibition percentage and phenols was observed. Asparagus origin was the only factor that led to significant differences: samples from Huétor-Tájar had higher values (POIC between 18 and 32) than those from Alcalá del Río (POIC of 5-9). Byproducts from the canning industry at Huétor-Tájar were also assayed for antioxidant activity; the results obtained suggested that byproducts could be considered as an excellent source of natural antioxidants.     

Antioxidant activity of organic extracts from aqueous infusions of sage

The antioxidant activity of aqueous infusions of sage emerges from specific components present in that herb. In an attempt to investigate the chemical nature and properties of these components, four organic solvent extracts from aqueous infusions of sage were examined. HPLC analyses of these extracts led to the separation of a number of components, of which four were identified and quantified through the use of standard compounds of known chromatographic HPLC profiles. These compounds are the diterpenes carnosic acid, carnosol, and rosmanol and the hydroxycinnamic acid caffeic acid. The antioxidant activity and polyphenol content were determined in the four organic solvent extracts and the left-over aqueous fraction. Both polyphenolic and nonpolyphenolic substances present in the extracts arise as significant contributors to the observed antioxidant activity of the derived extracts and thus sage itself. In this sense, they reflect the antioxidant potential of the aqueous infusions of sage toward reactive oxygen species generated through variable mechanisms of iron-promoted oxidative processes.     

Antioxidant activity of methanol extracts obtained from Plantago species

Antioxidative activities of methanol extracts from five Plantago species (P. afra, P. coronopus, P. lagopus, P. lanceolata, and P. serraria) were characterized by the DPPH scavenging test and the inhibition of Fe2+/ascorbate-induced lipid peroxidation on bovine brain liposomes. All extracts showed antioxidant activity in both methods. Whereas P. serraria exhibited the strongest activity as a DPPH scavenger, P. lanceolata and P. serraria were found to be the most active in the lipid peroxidation inhibition assay. The extracts were investigated regarding their composition by different colorimetric techniques, such as the content of total phenolic compounds by the Folin-Ciocalteu assay, flavonoids by AlCl3 reagent, phenylpropanoid glycosides (PPGs) by Arnow reagent, and iridoids by Trim-Hill assay. A high correlation was found between the scavenging potency and the total phenolic and phenylpropanoid content of the extracts but not between the lipid peroxidation potency and the extract composition. P. serraria is presented as a possible new source of natural antioxidants.     

Antioxidant composition in cherry and high-pigment tomato cultivars

Fourteen cultivars of cherry tomatoes and four cultivars of high-pigment tomato hybrids were cultivated in southern Italy, and the red-ripe fruits were analyzed for their content in different classes of antioxidants and for their antioxidant activity. Among the different cultivars, significant differences were found between lycopene, beta-carotene, alpha-tocopherol, vitamin C (ascorbic acid and dehydroascorbic acid), and total phenolic and flavonoid contents. LS203 and Corbus appear to be the cultivars with the highest content of lipophilic and hydrophilic antioxidants among cherry tomatoes, respectively. All cultivars of high-pigment tomato hybrids showed an expected exceptionally high lycopene content. Among them, the highest content of lipophilic and hydrophilic antioxidants was found in cv. HLY 13. Hydrophilic and lipophilic antioxidant activities were both significantly influenced by genotype. Such results highlight an existing unexploited variability in tomato germplasm and stress the need to evaluate the biodiversity and to support conventional breeding programs to improve tomato nutritional value.     

Antioxidant properties and phytochemical characteristics of extracts from Lactuca indica

Lactuca indica (Compositae) is an edible wild vegetable, used as a folk medicine in anti-inflammatory, antibacterial, and other medications in Asia. This is the first scientific evaluation of the chemopreventive therapeutic properties of L. indica using five antioxidation assay systems. An extract from L. indica was found to possess significant free radical scavenging activity, effectively protecting phix174 supercoiled DNA against strand cleavage and reducing oxidative stress in human promyelocytic leukemia HL-60 cells. Moreover, extracts of L. indica almost totally inhibited nitric oxide production and the mRNA expression of inducible nitric oxide synthase, at a dosage of 100 microg/mL, in LPS-stimulated macrophage RAW264.7 cells. Bioactivity-guided chromatographic fractionation and metabolite profiling coupled with spectroscopic analyses revealed that the six phenolic compounds, that is, protocatechulic acid (1), methyl p-hydroxybenzoate (2), caffeic acid (3), 3,5-dicaffeoylquinic acid (4), luteolin 7-O-beta-glucopyranoside (5), and quercetin 3-O-beta-glucopyranoside (6), are the major antioxidative constituents in the L. indica extract.     

Antioxidant activities and phenolic composition of extracts from Greek oregano,Greek sage,and summer savory

Oregano vulgare L. ssp. hirtum (Greek oregano), Salvia fruticosa (Greek sage), and Satureja hortensis (summer savory) were examined as potential sources of phenolic antioxidant compounds. The antioxidant capacities (antiradical activity by DPPH* test, phosphatidylcholine liposome oxidation, Rancimat test) and total phenol content were determined in the ethanol and acetone extracts of the dried material obtained from the botanically characterized plants. The ground material was also tested by the Rancimat test for its effect on the stability of sunflower oil. The data indicated that ground material and both ethanol and acetone extracts had antioxidant activity. Chromatographic (TLC, RP-HPLC) and NMR procedures were employed to cross-validate the presence of antioxidants in ethanol and acetone extracts. The major component of all ethanol extracts was rosmarinic acid as determined by RP-HPLC and NMR. Chromatography indicated the presence of other phenolic antioxidants, mainly found in the acetone extracts. The presence of the flavones luteolin and apigenin and the flavonol quercetin was confirmed in the majority of the extracts by the use of a novel (1)H NMR procedure, which is based on the strongly deshielded OH protons in the region of 12-13 ppm without previous chromatographic separation. This deshielding may be attributed to the strong intramolecular six-membered ring hydrogen bond of the OH(5)...CO(4) moiety.     

Antioxidant properties of methanolic extracts from several ear mushrooms.

Five kinds of ear mushrooms are commercially available in Taiwan, including black, red, jin, snow, and silver ears. Methanolic extracts were prepared from these ear mushrooms, and their antioxidant properties were studied. For all methanolic extracts from ear mushrooms, the antioxidant activities in the 1,3-diethyl-2-thiobarbituric acid method were moderate (38.6 approximately 74.6%) at 1.0-5.0 mg/mL. Methanolic extracts from red, jin, and snow ears showed excellent antioxidant activities in the conjugated diene method at 5.0 mg/mL. At 5.0 mg/mL, reducing powers of methanolic extracts were in the descending order of snow > black approximately red approximately jin > silver ears. The scavenging effect of methanolic extracts from ear mushrooms on 1,1-diphenyl-2-picrylhydrazyl radicals was excellent except for that from silver ears. Ear mushroom extracts were not good scavengers for hydroxyl free radicals but were good chelators for ferrous ions. Naturally occurring antioxidants, including ascorbic acid, tocopherols, and total phenols, were found in the methanolic extracts. However, beta-carotene was not detected. Total antioxidant components were 15.69, 30.09, 27.83, 49.17, and 31.70 mg/g for black, red, jin, snow, and silver ears, respectively.     

Antioxidant properties of evening primrose seed extracts

The antioxidant activity of extracts of evening primrose seeds (SE) and a commercially extracted filter cake (FC) were determined. The SE and FC were extracted with methanol/water (9:1) followed by evaporation and concentration. Extracts were tested in a bulk oil system and an oil-in-water emulsion using safflower oil as the major source of lipids. The antioxidant activity of the extracts was compared to that of a control and to that of butylated hydroxytoluene (BHT), singly, and in combination. Antioxidant activity was measured by the co-oxidation of beta-carotene, an oxidative stability instrument, conjugated dienes, and headspace analysis of hexanal. The SE extract had greater antioxidant activity than the FC extract. The SE extract was more effective in controlling the oxidation in the oil-in-water model system than in the bulk oil system. The activity of SE was concentration dependent, and at higher concentrations the SE was as effective as BHT, but it required higher concentrations because of its lack of purity. Synergism between SE and BHT was demonstrated in both model systems.     

Antioxidant and chemopreventive properties of polyphenolic compounds derived from Greek legume plant extracts

Recently, phytochemical compounds present in legumes have gained a lot of interest because they are considered to be possible chemopreventive agents. In the present study, 14 polyphenolic compounds were extracted and identified from two unique varieties of Leguminosae family plants cultivated in Greece and screened for their antioxidant and chemopreventive properties. Ten polyphenolic fractions, which are mainly mixtures of two compounds and five pure flavonoids, were isolated from the methanolic extracts of aerial plant parts of Vicia faba and Lotus edulis (Leguminosae), respectively. All of these fractions exhibited significant DPPH(*) radical scavenging capacity. Furthermore, they exerted significant protective activity against free radical-induced DNA damage. This activity was more potent against ROO(*) radical-induced DNA damage than against that induced by OH(*) radicals. Finally, they exhibited significant ability to inhibit the activity of the topoisomerase I enzyme. These results imply that the polyphenolic compounds identified in the fractions were responsible of the observed properties of the fractions and the initial extracts and indicate different mechanisms by which these phenolic compounds may act as chemopreventive agents.     

Antioxidant properties of bran extracts from Trego wheat grown at different locations

The effects of growing conditions during the grain-filling period, including high temperature stress, total solar radiation, and average daily solar radiation, on the antioxidant properties of Trego wheat were evaluated. Bran extracts were prepared from Trego wheat, grown at four nonirrigated and one irrigated location in Colorado, and compared for their radical scavenging activities against ABTS*+ and DPPH*, Fe(2+) chelating capacities, and total phenolic contents. Significant differences in radical scavenging activities, chelating capacities, and total phenolic contents were detected among Trego bran samples grown at different locations, suggesting that growing conditions may influence the antioxidant properties of wheat. The bran sample obtained from Fort Collins had the strongest scavenging activity against either ABTS*+ or DPPH* radicals and the greatest chelating activity, whereas the highest total phenolic content was detected in bran samples from Walsh, indicating that each antioxidant activity may respond to the environmental changes differently. Positive correlations were detected between the DPPH* scavenging activity and either total solar radiation (r = 0.97, p = 0.03) or average daily solar radiation (r = 0.97, p = 0.03). In addition, HPLC analysis detected the presence of ferulic, syringic, vanillic, p-hydroxybenzoic, and coumaric acids in wheat bran. Additional research is needed to further investigate the effects of environmental conditions and the interactions between genotype and environmental factors on the antioxidant properties of wheat to promote the production of wheat with improved antioxidant properties by optimizing the growing conditions for a selected genotype.     

Phytochemical, antioxidant, and antiproliferative properties of seed oil and flour extracts of Maryland-grown tobacco cultivars

To determine the possible alternative use of tobacco, the seeds representing seven Maryland tobacco cultivars were investigated for their phytochemical, antioxidant, and antiproliferative properties. Tobacco seed oils were extracted by the Soxhlet method, and analyzed for their yield, density, refractive index, fatty acid profiles, and tocopherol profile. The defatted flours were extracted in 50% acetone and 80% ethanol. The tobacco seed oil and flour extracts were analyzed for total phenolic contents (TPC) and scavenging capacities against peroxyl, hydroxyl and 2,2-diphenyl-1-picryhydrazyl (DPPH) radicals. The fatty acid compositions of phospholipids and the protein content of the flours were also analyzed. In addition, oil and flour extracts of varieties MD609 and MD609LA were evaluated for their antiproliferative effects on HT-29 human colon cancer cells. All of the tested extracts significantly inhibited HT-29 cell proliferation except that from MD609 oil. The data from this study suggest the potential alternative use of tobacco seeds in developing natural antioxidants and antiproliferative agents for improving human health.     

Nuclear and chloroplast microsatellite markers to assess genetic diversity and evolution in hazelnut species, hybrids and cultivars

The US Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository in Corvallis, Oregon, preserves more than 800 accessions of hazelnut (Corylus), including C. avellana cultivars and representatives of 10 other recognized shrub and tree species. Characterization and study of genetic diversity in this collection require cross-transferable markers, such as trinucleotide microsatellite or simple sequence repeat (SSR) markers and universal chloroplast SSR markers. We developed new SSR markers and evaluated 114 Corylus accessions representing 11 species and 44 interspecific hybrids. Eight of 23 SSRs generated easy-to-score alleles in all species and seven were highly polymorphic. For those seven, the average heterozygosity was moderate at 0.49, and mean allele number, genetic diversity and polymorphism information index were high at 11.71, 0.79 and 0.76, respectively. The three most polymorphic SSRs were CaC-C008, CaC-C040 and CaC-C118. Neighbor-joining (NJ) clustering and structure analysis agreed with classical taxonomic analysis and supported inclusion of C. maxima within the large polymorphic species, C. avellana. Analysis also indicated that C. californica is a distinct species rather than a botanical variety of C. cornuta. Six universal cpSSRs were polymorphic in Corylus and generated 21 distinct chlorotypes with an average of 3 alleles per locus. Diversity at these cpSSRs was high and ranged from 0.33 to 0.64, with an average of 0.54. Incongruence in NJ topologies between the nuclear and chloroplast markers could be attributed to chloroplast capture related to hybridization during the ancestral diversification of the genus, or to homoplasy. The phylogeographical relationships among the 21 chlorotypes in the 11 Corylus species support Asia as a refugium where several hazelnut lineages survived during glaciation and from which they continued to evolve after dispersal from Asia through the Mediterranean to Europe, and across the Atlantic and/or the Bering land bridge to North America.     

Antioxidant properties of bran extracts from "Akron" wheat grown at different locations

Bran extracts of Akron wheat grown at four nonirrigated and one irrigated testing locations were examined and compared for their free radical scavenging properties against the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(*)) and the radical cation ABTS(*)(+), chelating capacities, and total phenolic content (TPC) to determine the potential effects of environmental factors on the antioxidant properties of hard winter wheat. The environmental factors included total solar radiation, average daily solar radiation, and number of hours exceeding 32 degrees C. The results showed that bran samples from different growing locations may significantly differ in their radical scavenging activities against both DPPH(*) and ABTS(*)(+), chelating capacities, and TPC. A significant negative correlation was detected between the chelating activities of the bran samples from the four nonirrigated locations and total solar or daily average solar radiation (r = -0.999 and P = 0.001). These data suggest potential influences of growing conditions on the antioxidant properties of hard winter wheat and the possibility of producing wheat that is strong in a selected antioxidant property by optimizing the growing conditions of a selected wheat variety. More research is required to further investigate the relationship among antioxidant properties and environmental factors using different wheat varieties and larger sample sizes.     

Antioxidant properties of prepared blueberry (Vaccinium myrtillus) extracts

A blueberry extract (A) and two anthocyanin-derived extracts (B and C) were prepared. The contents of polyphenols, flavonoids, anthocyanins, and anthocyanin-derived pigments of the extracts were determined for the first time. The pigment profile of blueberry extract A corresponded to 15 anthocyanins, whereas extract B was mainly composed of anthocyanin-pyruvic acid adducts of the blueberry original anthocyanins and extract C was mainly composed of the respective vinylpyranoanthocyanin-catechins (portisins). The extracts' abilities to inhibit lipid peroxidation, induced by 2,2'-azobis(2-methyl-propanimidamide) dihydrochloride in a liposomal membrane system were examined. The antioxidant capacities of the extracts were evaluated through monitoring oxygen consumption and by measuring the formation of conjugated dienes. All of the extracts provided protection of membranes against peroxyl radicals by increasing the induction time of oxidation. This effect increased with the polyphenol content and with the structural complexity of the anthocyanin-derived pigments of the extracts. The pigments present in extract C seemed to induce a higher protection of the liposome membranes toward oxidation. In addition, the antiradical properties and the reducing power of the extracts were determined by using DPPH and FRAP methods, respectively. The results from these assays were in agreement with those obtained with the liposome membranes.     

Beta-carotene isomer composition of sub- and supercritical carbon dioxide extracts. Antioxidant activity measurement

In the present work sub- and supercritical extraction conditions using carbon dioxide were studied in order to obtain extracts with different compositions from the green microalgae Dunaliella salina. Different compositions of beta-carotene isomers were identified in the extracts by using HPLC-DAD. Also, antioxidant activity of the extracts was measured using a TEAC assay. An experimental design was applied considering two factors, extraction pressure and temperature, in a wide range of values, trying to maximize the extraction yield. Higher yields were obtained at high pressures and low temperatures, that is, at higher CO2 densities. Attempts were made to correlate the antioxidant activity of the extracts with their chemical composition by means of principal component analysis. A certain relationship was found between their antioxidant activity and the isomeric composition of beta-carotenes. As a result, an original equation is proposed to predict the antioxidant activity of extracts from D. salina in terms of the ratio 9-cis-beta-carotene/all-trans-beta-carotene, the concentration of alpha-carotene, and, especially, the concentration of 9-cis-beta-carotene.     

Catalytic properties of alcohol acyltransferase in different strawberry species and cultivars

The substrate specificity of alcohol acyltransferase (AAT) enzymes from different strawberry varieties was studied. Proteins with AAT activity from fruits of Fragaria x ananassa Duch. cv. Oso Grande were purified to apparent homogeneity and used for kinetic studies with different straight-chain alcohols and acyl-CoAs. K(m) values obtained for Oso Grande enzyme with six different alcohols, using acetyl-CoA as cosubstrate, decreased with increasing length of the alcohol chain. In similar experiments the increase in the acyl-CoA carbon chain was also found to be correlated with a higher substrate specificity. Heptanol (K(m) = 0.73 mM) and hexanoyl-CoA (K(m) = 0.41 mM) were the best substrates for Oso Grande AAT. Comparative catalytic studies were carried out with AAT partially purified extracts from the wild type Fragaria vesca and five commercial strawberry varieties: Tudnew, Carisma, Camarosa, Sweet Charlie, and Eris. The specificities of these enzymes toward five selected alcohols and acyl-CoAs reflected interesting cultivar differences.     

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.     

The effects of iron,mercury, and copper ions on the acid-base properties of aqueous soil extracts

This article presents indicators of the influences of salts of iron, mercury, and copper on the acid- base properties of aqueous extracts from the upper soil horizons of taiga zones. Their acidification is estab- lished; under the influence of metals, the processes responsible for elevated levels of protons in the extracts are identified, viz., the hydrolysis of metal ions and their inclusion in the complexation with water-soluble organic substances. We discovered the effects on these processes of organic materials of the extracts, as well as of the properties of metals and the type and amount of salts, in whose composition the metals are included in the extracts.