Screening of antioxidant potential of Arctic lichens

Antioxidants are compounds that scavenge the free radicals produced in living organisms. The antioxidant potential of eight Arctic lichen species was evaluated in vitro using free radical scavenging activity (FRS), inhibition of lipid peroxidation (ILP), and Trolox equivalent antioxidant capacity assay (TEAC). FRS activities of lichen species in various organic solvents such as methanol, ethanol, acetone, and dimethyl sulphoxide (DMSO) were in the range 9.6–51.77%, while ILP activities in these solvents ranged from 32.5 to 82.43%. Pseudophebe pubescens showed the highest ILP (82.43%) and FRS (51.77%) activities as compared to other lichen species and the standard antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The TEAC value was also found to be higher in all species compared to the standard water soluble vitamin E analog Trolox (3.9 mM). The order of antioxidative activities in lichen species was Pseudophebe pubescens > Cladonia amaurocraea > Cladonia mediterranea > Physcia caesia > Flavocetraria nivalis > Cetraria fastigata > Xanthoria elegans > Umbilicaria hyperborea. This is the first report of the measurement of antioxidant potential in Arctic lichens.     

Antioxidant properties of potentially probiotic bacteria: in vitro and in vivo activities

Thirty-four strains of lactic acid bacteria (seven Bifidobacterium, 11 Lactobacillus, six Lactococcus, and 10 Streptococcus thermophilus) were assayed in vitro for antioxidant activity against ascorbic and linolenic acid oxidation (TAA_AA and TAA_LA), trolox-equivalent antioxidant capacity (TEAC), intracellular glutathione (TGSH), and superoxide dismutase (SOD). Wide dispersion of each of TAA_AA, TAA_LA, TEAC, TGSH, and SOD occurred within bacterial groups, indicating that antioxidative properties are strain specific. The strains Bifidobacterium animalis subsp. lactis DSMZ 23032, Lactobacillus acidophilus DSMZ 23033, and Lactobacillus brevis DSMZ 23034 exhibited among the highest TAA_AA, TAA_LA, TEAC, and TGSH values within the lactobacilli and bifidobacteria. These strains were used to prepare a potentially antioxidative probiotic formulation, which was administered to rats at the dose of 10⁷, 10⁸, and 10⁹ cfu/day for 18 days. The probiotic strains colonized the colon of the rats during the trial and promoted intestinal saccharolytic metabolism. The analysis of plasma antioxidant activity, reactive oxygen molecules level, and glutathione concentration, revealed that, when administered at doses of at least 10⁸ cfu/day, the antioxidant mixture effectively reduced doxorubicin-induced oxidative stress. Probiotic strains which are capable to limit excessive amounts of reactive radicals in vivo may contribute to prevent and control several diseases associated with oxidative stress.     

High diversity of root associated fungi in both alpine and arctic <Emphasis Type="Italic">Dryas octopetala</Emphasis>

Background  

Dryas octopetala is a widespread dwarf shrub in alpine and arctic regions that forms ectomycorrhizal (ECM) symbiotic relationships with fungi. In this study we investigated the fungal communities associated with roots of D. octopetala in alpine sites in Norway and in the High Arctic on Svalbard, where we aimed to reveal whether the fungal diversity and species composition varied across the Alpine and Arctic regions. The internal transcribed spacer (ITS) region of nuclear ribosomal DNA was used to identify the fungal communities from bulk root samples obtained from 24 plants.     

Development of selection method for Glycyrrhiza uralensis superior clones with high-glycyrrhizic acid contents using DNA sequence polymorphisms in glycyrrhizic acid biosynthetic genes

Glycyrrhiza plants are important resources for sweeteners and medicines, because underground parts of them contain glycyrrhizic acid (GL), which has sweet taste and various pharmacological activities (ex. anti-inflammatory, antiallergy, antiviral activity, etc.). Although such importance of them, their supply still depends principally on the collection of wild plants. Therefore, it is an important issue to develop stable and efficient production system of Glycyrrhiza plants. To overcome this problem, we established the hydroponic cultivation system of Glycyrrhiza uralensis and selected superior G. uralensis clones with high-GL contents in the containment greenhouse. In this study, we aimed to develop a method of selecting these superior G. uralensis clones by DNA sequence polymorphisms in biosynthetic genes. Among the DNA sequences of GL biosynthetic key enzyme gene (CYP88D6), we found Glycyrrhiza species and clone-specific polymorphisms in intronic regions. By using these polymorphisms, discrimination among Glycyrrhiza species and G. uralensis clones became possible. Furthermore, the appearance frequency of superior clone-specific alleles in cloned CYP88D6 sequences was correlated with GL contents in crude drugs collected from the Japanese market. We also observed the tendency that G. uralensis seedlings having superior clone-specific alleles of CYP88D6 gene showed higher secondary metabolite productivity than those without the alleles. These results indicated that superior clone-specific alleles of CYP88D6 gene could be applied as DNA markers for selecting G. uralensis clones accumulating high secondary metabolites.     

Mesorhizobium sp. J8 can establish symbiosis with Glycyrrhiza uralensis,increasing glycyrrhizin production

Licorice (Glycyrrhiza uralensis) is a medicinal plant that contains glycyrrhizin (GL), which has various pharmacological activities. Because licorice is a legume, it can establish a symbiotic relationship with nitrogen-fixing rhizobial bacteria. However, the effect of this symbiosis on GL production is unknown. Rhizobia were isolated from root nodules of Glycyrrhiza glabra, and a rhizobium that can form root nodules in G. uralensis was selected. Whole-genome analysis revealed a single circular chromosome of 6.7 Mbp. This rhizobium was classified as Mesorhizobium by phylogenetic analysis and was designated Mesorhizobium sp. J8. When G. uralensis plants grown from cuttings were inoculated with J8, root nodules formed. Shoot biomass and SPAD values of inoculated plants were significantly higher than those of uninoculated controls, and the GL content of the roots was 3.2 times that of controls. Because uninoculated plants from cuttings showed slight nodule formation, we grew plants from seeds in plant boxes filled with sterilized vermiculite, inoculated half of the seedlings with J8, and grew them with or without 100 µM KNO₃. The SPAD values of inoculated plants were significantly higher than those of uninoculated plants. Furthermore, the expression level of the CYP88D6 gene, which is a marker of GL synthesis, was 2.5 times higher than in inoculated plants. These results indicate that rhizobial symbiosis promotes both biomass and GL production in G. uralensis.     

Changes in essential oil,kava pyrones and total phenolics of Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm. leaves exposed to copper sulphate

Essential oils, total phenolics, dihydro-5,6-dehydrokawain (DDK) and antioxidant and antibacterial activities were investigated in Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm. plants, that had been sprayed with copper sulphate 24 h beforehand. Ethyl acetate extract of copper-treated plants contained increased levels of total phenolics, had higher antioxidant activity assayed by DPPH and β-carotene bleaching methods and exhibited higher antibacterial activity against Bacillus cereus than that of non-treated plants. Contents of DDK, vanillin and cinnamic acid were significantly higher in chloroform and ethyl acetate extracts of A. zerumbet plants following exposure to copper. Volatile components that increased after copper treatment include: 1,8-cineol, camphor, borneol, and terpinene-4-ol. Foliar application of copper sulphate may regulate the antioxidant compounds in A. zerumbet plants, influencing its antioxidant and antibacterial activities.     

Quantitative analysis of polyphenols and antioxidant activity in four Daphne L. species

The content of biologically active phenolic compounds (total polyphenols, tannins, flavonoids, and phenolic acids) were determined using spectrophotometry in four wild Croatian species of Daphne L. in the family Thymelaeaceae (Daphne alpina, D. cneorum, D. laureola, and D. mezereum). The concentration of total flavonoids (TF) was highest in the leaves of these Daphne species (0.12?C0.51% dry herb weight, DW) whereas the content of other phenolic compounds analyzed were highest in the roots, including total polyphenols (TP; 2.71?C19.03% DW), tannins (T; 1.14?C7.39% DW), and total phenolic acids (TPA; 0.12?C0.87% DW). D. alpina contained the highest amount of polyphenols, with the exception of flavonoids, where maximum concentrations were found in D. laureola. We also examined the antioxidant activity of leaf, stem, and root extracts. All extracts analyzed demonstrated high free radical scavenging activity with the highest concentration in the leaf extracts of D. alpina. Leaf extracts of D. cneorum showed the highest antioxidant activity in a ??-carotene bleaching assay.     

Arbuscular mycorrhizal symbiosis modulates antioxidant response in salt-stressed Trigonella foenum-graecum plants

An experiment was conducted to evaluate the influence of Glomus intraradices colonization on the activity of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), peroxidase (PX), ascorbate peroxidase (APX), and glutathione reductase (GR)] and the accumulation of nonenzymatic antioxidants (ascorbic acid, α-tocopherol, glutathione, and carotenoids) in roots and leaves of fenugreek plants subjected to varying degrees of salinity (0, 50, 100, and 200 mM NaCl) at two time intervals (1 and 14 days after saline treatment, DAT). The antioxidative capacity was correlated with oxidative damage in the same tissue. Under salt stress, lipid peroxidation and H₂O₂ concentration increased with increasing severity and duration of salt stress (DoS). However, the extent of oxidative damage in mycorrhizal plants was less compared to nonmycorrhizal plants. The study reveals that mycorrhiza-mediated attenuation of oxidative stress in fenugreek plants is due to enhanced activity of antioxidant enzymes and higher concentrations of antioxidant molecules. However, the significant effect of G. intraradices colonization on individual antioxidant molecules and enzymes varied with plant tissue, salinity level, and DoS. The significant effect of G. intraradices colonization on antioxidative enzymes was more evident at 1DAT in both leaves and roots, while the concentrations of antioxidant molecules were significantly influenced at 14DAT. It is proposed that AM symbiosis can improve antioxidative defense systems of plants through higher SOD activity in M plants, facilitating rapid dismutation of O₂ ^- to H₂O₂, and subsequent prevention of H₂O₂ build-up by higher activities of CAT, APX, and PX. The potential of G. intraradices to ameliorate oxidative stress generated in fenugreek plants by salinity was more evident at higher intensities of salt stress.     

Antioxidant Activity of Antiviral Proteins from Celosia cristata

The antioxidant activity test of Celosia cristata antiviral proteins (CCP-25 and CCP-27) using ferric reducing antioxidant power (FRAP) assay in vitro indicated that these proteins are strong antioxidants. The increase in activities of redox-enzymes such as peroxidase, catalase and polyphenol oxidase on tobacco mosaic virus (TMV) inoculation of test plants, was inhibited when plants were treated with CCP-25 before TMV inoculation. The activity of phenylalanine ammonia lyase, involved in biosynthesis of antioxidative compounds was also inhibited. This is the first ever report where plant antiviral proteins have been shown to have strong antioxidative property. A possible correlation between antioxidant activity of CCPs and their antiviral activity is speculated.     

红花桑寄生叶提取物的抗氧化活性及酚类物质分析

采用DPPH法、TEAC法、FRAP法对红花桑寄生叶不同溶剂提取物的抗氧化活性进行体外评价,并测定其总酚、总黄酮含量。结果表明,溶剂种类对红花桑寄生叶提取物的得率、总酚、总黄酮及抗氧化活性影响显著。在3种评价方法中,不同溶剂提取物的抗氧化活性均表现出不同程度的量效依赖关系。3种溶剂提取物的抗氧化活性强弱依次为丙酮提取物 >甲醇提取物 >水提取物,其中80%丙酮提取物(总酚含量最高,达276.83mg/g)抗氧化活性最强,清除DPPH自由基能力EC₅₀值为0.247,FRAP值(FeSO₄ mmol/100g)为115.81,浓度为1.0mg/ml时,TEAC值为2.04。     

Community Structure of Rhizomicrobiomes in Four Medicinal Herbs and Its Implication on Growth Management

Medicinal plants are the basic materials of traditional Chinese medicine. Soil characteristics and microbial contribution play important roles in the growth and product quality of medicinal plants, but the link between them in the rhizosphere of medicinal plants has been overlooked. Accordingly, Mentha haplocalyx, Perilla frutescens, Glycyrrhiza uralensis, and Astragalus membranaceus, four plants used in traditional Chinese medicines, were investigated in this study in order to elucidate bacterial and arbuscular mycorrhizal fungal (AMF) diversity in the rhizosphere and its possible association with soil quality. DGGE-based 16S rRNA and 18S rRNA gene sequencing results indicated that the diversity of both bacteria and AMF in Glycyrrhiza uralensis and Astragalus membranaceus was significantly higher than those in Mentha haplocalyx and Perilla frutescens, suggesting that medicinal plants have different preferences even under the same conditions. In addition, enzymatic activities and nutrition were enhanced in the rhizospheric soil of Mentha haplocalyx and Perilla frutescens, and the correlation among AMF diversity, soil enzymatic activities and nutrition was confirmed using RDA analysis. These results suggest the potential to grow medicinal plants with a reasonable rotation or intercrop in order to maintain long-term continuous soil development.     

Phenolic production and antioxidant properties of some Macedonian medicinal plants

Investigations have been made to study the production of phenolic compounds (total phenolics, flavonoids and phenylpropanoids) and total antioxidant capacity in 27 Macedonian traditional medicinal plants to improve its potential as a source of natural antioxidants. Antioxidant potential of plant extracts was analyzed by five different assays: cupric reducing antioxidant capacity (CUPRAC), phosphomolybdenum method (PM), reducing power (RP), 2,2-diphenyl-1-picrylhydrazyl (DPPH^·) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS^·+) radical scavenging activity. Origanum vulgare extract consistently exhibited the highest content of phenolic compounds and the strongest antioxidant capacity based on the tests performed, and can be proposed as a promising source of natural antioxidants. Melissa officinalis and Salvia ringens were also identified as valuable sources of antioxidant compounds. A positive linear correlation between antioxidant activity and total phenolics, flavonoids and phenylpropanoids indicates that these compounds are likely to be the main antioxidants contributing to the observed activities of evaluated plants. These findings suggest that the medicinal plants studied in this paper are good sources of bioactive compounds for the food and pharmaceutical industries.     

Environmental constraints on the growth,photosynthesis and reproductive development of Dryas octopetala at a high Arctic polar semi-desert,Svalbard

Opportunities exist in high Arctic polar semidesert communities for colonisation of unvegetated ground by long-lived clonal plants such as Dryas octopetala. This can be achieved by lateral spread of vegetative ramets, or by sexual reproduction and seedling recruitment. The objectives of this study were (1) to determine whether these two means of proliferation show differential sensitivity to contrasting components of the abiotic environment (temperature, soil nutrient and water availability) and (2) to evaluate the potential for D. octopetala to respond to climate change by an increase in cover and biomass in polar semi-desert communities. Factorial environmental manipulations of growing season temperature, soil nutrient and water status were conducted over 3 years at a polar semi-desert community in Svalbard, Norway (78°56.12N, 11°50.4E) and both clonal and sexual reproductive performance, together with instantaneous net photosynthesis (P_n), were recorded during the third season (1993). D. octopetala capitalised rapidly on an amelioration in the availability of inorganic nutrients (N, P and K) by an expansion in leaf area and biomass supported by increased P_n per unit leaf weight, and by apparent luxury uptake of nutrients (particularly P). Several facets of sexual reproductive development and seed viability were markedly improved by elevated temperatures or soil nutrient availability. Thus although D. octopetala is a long-lived clonal plant, with many traits characteristic of stress resistance syndrome, it showed considerable phenotypic plasticity in response to environmental manipulations. The results support the hypothesis that clonal growth confers survival potential during unfavourable years, together with the ability to capitalise on nutrient flushes and recycle nutrients internally. Continued investment in sexual reproduction ensures that seed setting is successful during favourable years, even if these occur infrequently. Cimate warming in the high Arctic could thus result in changes in the cover, biomass and the relative significance of clonal versus sexual proliferation of D. octopetala (and thus the genetic diversity of the population) but the long-term responses will probably be constrained by lack of available nutrients.     

Antidiabetic and Antioxidant Effects and Phytochemicals of Mulberry Fruit (Morus alba L.) Polyphenol Enhanced Extract

The antidiabetic and antioxidant activities of the ethyl acetate-soluble extract (MFE) of mulberry fruit (Morus alba L.) were investigated. In vitro, MFE showed potent α-glucosidase inhibitory activity and radical-scavenging activities against DPPH and superoxide anion radicals. In vivo, MFE could significantly decrease fasting blood glucose (FBG) and glycosylated serum protein (GSP), and increase antioxidant enzymatic activities (SOD, CAT, GSH-Px) in streptozotocin (STZ)-induced diabetic mice. Bioactivity-guided fractionation of the MFE led to the isolation of 25 phenolic compounds, and their structures were identified on the basis of MS and NMR data. All the 25 compounds were isolated from mulberry fruit for the first time. Also, the α-glucosidase inhibitory activity and antioxidant activity of the phenolics were evaluated. Potent α-glucosidase inhibitory and radical-scavenging activities of these phenolics suggested that they may be partially responsible for the antidiabetic and antioxidant activities of mulberry fruit.     

Silicon nutrition alleviates the lipid peroxidation and ion imbalance of <Emphasis Type="Italic">Glycyrrhiza uralensis</Emphasis> seedlings under salt stress

Soil salinity reduces growth of Glycyrrhiza uralensis in arid and semi-arid areas of north-west in China. Silicon (Si) nutrition may alleviate salt stress in many crops including grain crop, fruit crop, and vegetable crop. In this study, the alleviating effects of Si on growth characteristics, antioxidant enzyme activity (SOD and POD) and MDA concentration, and K⁺ and Na⁺ concentrations in G. uralensis seedlings subjected to 50 mM NaCl stress were investigated. The results showed that NaCl stress imposed significant reduction in root length, secondary root number, leaf number, and stem and total dry weight of G. uralensis. NaCl stress also significantly reduced the activities of SOD and POD, and ration of K⁺/Na⁺, but significantly increased MDA concentration in leaves of G. uralensis seedling. The addition of Si increased SOD and POD activities, and reduced MDA concentration, which resulting in greater reactive oxygen species detoxification and lower lipid peroxidation. Si also significantly increased the ratio of K⁺/Na⁺ in stem and leaves of G. uralensis. In conclusion, Si could alleviate adverse effects of salt stress probably by decreasing Na⁺ concentration and improving antioxidant enzyme activity of G. uralensis, and these alleviating effects were dependent on Si concentration and on Si processing time.     

Resistance to photoinhibition of photosystem II and catalase and antioxidative protection in high mountain plants

In leaves of three alpine high mountain plants, Homogyne alpina, Ranunculus glacialis and Soldanella alpina, both photosystem II (PSII) and the enzyme catalase appeared to he highly resistant to photoinactivation under natural field conditions. While the Dl protein of PSII and catalase have a rapid turnover in light and require continuous new protein synthesis in non-adapted plants, little apparent photoinactivation of PSII or catalase was induced in the alpine plants by translation inhibitors or at low temperature, suggesting that turnover of the Dl protein and catalase was slow in these leaves. In vitro PSII was rapidly inactivated in light in isolated thylakoids from H. alpina and R. glacialis. In isolated intact chloroplasts from R. glacialis, photoinactivation of PSII was slower than in thylakoids. Partially purified catalase from R. glacialis and S. alpina was as sensitive to photoinactivation in vitro as catalases from other sources. Catalase from H. alpina had, however, a 10-fold higher stability in light. The levels of xanthophyll cycle carotenoids, of the antioxidants ascorbate and glulathione, and of the activities of catalase, superoxide dismutase and glutathione reductase were very high in S. alpina, intermediate in H. alpina, but very low in R. glacialis. However, isolated chloroplasts from all three alpine species contained much higher concentrations of ascorbate and glutathione than chloroplasts from lowland plants.     

Quality evaluation of snow lotus (Saussurea): quantitative chemical analysis and antioxidant activity assessment

Snow lotus is commonly used as a medicinal plant and has great pharmacological value. To protect these endangered plants, in vitro propagation and cell cultures have been established in order to meet the growing market demand. The phenolic composition, antioxidant activities, total phenolic content (TPC) and total flavonoid content (TFC) from three most commonly used species, in vitro propagated lines and the cell cultures were investigated to qualify their pharmacological value. Quantitative analysis showed that the phenolics varied greatly among different species and the same species at different habitats. From this it can be inferred that the phenolics were influenced by genetic background and the environmental conditions. Significant correlations were observed between the antioxidant activity and several phenolics/TPC/TFC, suggesting that the phenolics are a major contributor of the antioxidant activity and are important for quality evaluation of snow lotus. Based on the abundance of phenolics, TPC, TFC and antioxidant activity, the order of the quality for wild species would be Saussurea involucrata > Saussurea medusa > Saussurea gossypiphora. For S. medusa, its quality judged by origin would be Shigatse > Lhasa > Nagqu. For in vitro propagated plants, the matured plants could be a reliable substitute for wild plants, and the dynamics of phenolics is critical for quality control of this monocarpic species. We provide the first report of quality comparison between the wild plants and the cell cultures. The advantages of developing cell cultures as alternatives for plants collected from the wild are discussed.     

Antioxidant and Antiproliferative Activities of Twenty-Four Vitis vinifera Grapes

Grapes are rich in phytochemicals with many proven health benefits. Phenolic profiles, antioxidant and antiproliferative activities of twenty-four selected Vitis vinifera grape cultivars were investigated in this study. Large ranges of variation were found in these cultivars for the contents of total phenolics (95.3 to 686.5 mg/100 g) and flavonoids (94.7 to 1055 mg/100 g) and antioxidant activities (oxygen radical absorbance capacity 378.7 to 3386.0 mg of Trolox equivalents/100 g and peroxylradical scavenging capacity14.2 to 557 mg of vitamin C equivalents/100 g), cellular antioxidant activities (3.9 to 139.9 µmol of quercetin equivalents/100 g without PBS wash and 1.4 to 95.8 µmol of quercetin equivalents /100 g with PBS wash) and antiproliferative activities (25 to 82% at the concentrations of 100 mg/mL extracts).The total antioxidant activities were significantly correlated with the total phenolics and flavonoids. However, no significant correlations were found between antiproliferative activities and total phenolics or total flavonoids content. Wine grapes and color grapes showed much higher levels of phytochemicals and antioxidant activities than table grapes and green/yellow grapes. Several germplasm accessions with much high contents of phenolics and flavonoids, and total antioxidant activity were identified. These germplasm can be valuable sources of genes for breeding grape cultivars with better nutritional qualities of wine and table grapes in the future.     

Inhibition of Helicobacter pylori growth and its cytotoxicity by 2-hydroxy 4-methoxy benzaldehyde of Decalepis hamiltonii (Wight & Arn); a new functional attribute

Helicobacter pylori mediated gastric ulcer and cancers are common global problems since it was found to colonize in ∼50% of gastric ulcer/cancer patients. Decalepis hamiltonii, (Asclepiadaceae family) extracts have been depicted with medicinal properties supporting the traditional knowledge of health beneficial attributes of D. hamiltonii. Previously we have shown that both aqueous as well as methanol extracts of D. hamiltonii containing abundant phenolics with predominant levels (20-40% of total phenolics) of 2-hydroxy-4-methoxy benzaldehyde (HMBA). Despite higher levels, HMBA contributed very little to the antioxidant activity (<10%) when compared to other phenolic compounds in the extract. In the current study we attempted to explore antimicrobial property, particularly anti-H. pylori activity, since traditional users document D. hamiltonii as a fighter of microbial infections. HMBA was isolated from the roots of D. hamiltonii by hydrodistillation and cold crystallization method; identified by HPLC and characterized using ESI-MS and confirmed by NMR studies as a compound of molecular mass 152 Da. Isolated HMBA was found to inhibit the growth of H. pylori, a potential ulcerogen in a dose dependent manner with MIC of ∼39 μg/mL as apposed to that of amoxicillin (MIC - 26 μg/mL) for which H. pylori is susceptible. Results were further substantiated by the lysis of H. pylori by electron microscopy and electrophoretic studies. Studies on the mechanism of action indicated the counteracting effect of vacuolating toxin (VacA) of H. pylori which otherwise would lead to host cell cytotoxicity. Further the increased binding ability of HMBA to DNA and protein offered an impact on DNA protectivity and bioavailability. Results for the first time provide a direct evidence for anti-microbial attribute of HMBA. Insignificant antioxidant attribute of HMBA also reveals the anti-H. pylori activity via mechanisms other than antioxidative routes.