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1.
Purnima Singh Shiv M. Singh Lisette M. D’Souza Solimabi Wahidullah 《Polar Biology》2012,35(12):1825-1836
Environmental stress in the Arctic region leads to damage in plant membranes as a result of oxidation processes. To withstand these stress conditions, plants are expected to produce antioxidants that differ from phenolics. Here, we investigated the chemical composition and antioxidative activities of four Arctic flowering plant species (Dryas octopetala, Carex rupestris, Silene uralensis and Deschampsia alpina.) through in vitro measurements of the free radical scavenging activities (FRS), inhibition of lipid peroxidation (ILP) and trolox equivalent antioxidant capacities (TEAC). D. octopetala exhibited the highest ILP (76.45?%) and FRS (86.58?%) activities. The TEAC values were higher than those of the Trolox vitamin E standard in all four species. Overall, the antioxidative activity was highest in D. octopetala, followed by C. rupestris, S. uralensis and D. alpina. Electrospray ionization tandem mass spectrometric (ESI–MS/MS) analysis of methanolic extracts of these plants revealed the presence of organoselenides, linear alkylbenzenesulfonates (LAS) and oligosaccharides, some of which are reported as antioxidants in the literature. Hence, it is likely that the antioxidant activities exhibited by these plants are not only related to the production of phenolics. This is the first report of the antioxidant potential of four Arctic flowering plants and the presence of selenides in D. octopetala and S. uralensis, and the production of LAS in C. rupestris. Our findings suggest that these plants can be used as nutraceutical sources of selenium and as biomarkers for environmental pollution. 相似文献
2.
Heng Luo Yoshikazu Yamamoto Jung A Kim Jae Sung Jung Young Jin Koh Jae-Seoun Hur 《Polar Biology》2009,32(7):1033-1040
Eight lichen species, Cetraria aculeata, Cladonia furcata, Pseudephebe pubescens, Sphaerophorus globosus, Stereocaulon alpinum, Umbilicaria antarctica, Usnea antarctica and Usnea aurantiacoatra, were collected from King George Island, maritime Antarctica, for the evaluation of antioxidant activities. Anti-linoleic
acid peroxidation activity, free radical scavenging activity, reducing power and superoxide anion scavenging activity were
assessed of methanol and acetone extract of the lichens in vitro. Extract of Umbilicaria antarctica, Cladonia furcata, Sphaerophorus globosus and Usnea antarctica were found to have strong in vitro antioxidant properties. In general, acetone extract exhibited stronger activities than
methanol extract. The activity-guided bioautographic TLC and HPLC analysis demonstrated that lecanoric acid was the main antioxidant
compound in the acetone extract of Umbilicaria antarctica, the most potent antioxidant lichen species among the test species. The results suggested that several Antarctic lichens and their substances can be used as novel bioresources of natural antioxidants. 相似文献
3.
Various solvent extracts of the lichen Usnea ghattensis showed good antioxidant activity. A methanol extract prevented lipid peroxidation by 87% followed by 65% in Trolox at 20 μg/ml. It also showed superoxide anion scavenging activity and free radical scavenging activity 56% and 73%, respectively. The known antioxidants butylated hydroxytoluene (BHT), butylated hydroxyanisol (BHA) and quercetin at similar concentrations showed superoxide anion scavenging activity of 68, 59 and 47% and free radical scavenging activity 83, 77 and 69%, respectively. In addition, these extracts were inhibitory against Bacillus licheniformis, Bacillus megaterium, Bacillus subtilis and Staphylococcus aureus with MIC values of 5–10 μg/ml.Received after revisions 10 May 2005 相似文献
4.
The aim of the research is to explore the overall in vitro antioxidant activity, total phenol content, reduction power and
antimicrobial activity of the methanol extracts of the lichens Cetraria pinastri, Cladonia digitata, Cladonia fimbriata, Fulgensia fulgens, Ochrolechia parella and Parmelia crinita. The methanol extract of the Cetraria pinastri showed a strong antioxidant activity, whereas the extracts of the species Fulgenesi fulgens, Cladonia fimbriata and Parmelia crinita showed the moderate one and the extract of the species Ochrolechia parella and Cladonia digitata the weak one. The methanol extract of the lichen Cetraria pinastri had the biggest total phenol content (32.9 mg/g of the dry extract). A certain correlation was established between the antioxidant
activity and the total phenol content for the researched lichen extracts. The work also explores the antimicrobial activity
of the methanol extracts of the mentioned species of lichens against six bacterial and eleven fungi species by the disc-diffusion
method and by establishing the minimum inhibitory concentration (MIC). The methanol extracts of the lichens Cetraria pinastri and Parmelia crinita showed the strongest both antibacterial and antifungal activity against most of the tested microorganisms. These researches
suggest that the lichens Cetraria prunastri can be used as new sources of the natural antioxidants and the substances with antimicrobial features. 相似文献
5.
《Redox report : communications in free radical research》2013,18(1-2):69-74
AbstractThe relativeThe relative activities of some hydrogen-donating antioxidants were assessed by comparing their activities with that of Trolox (Trolox equivalent antioxidant capacity, TEAC) for scavenging the ABTS radical cation (ABTS?+) generated in the aqueous phase. We have verified, however, that TEAC values may change with the concentration of compounds and with the measuring times used. Not withstanding, TEAC values do not differ significantly if the compounds have kinetic curves of ABTS?+ formation similar to that of Trolox. This is the case with ascorbic acid, whose TEAC values, determined by using five concentrations at three different measuring times, are very close. For the flavonoids studied (catechin, rutin, naringenin and silibinin) which have kinetic curves of ABTS?+ formation different from that of Trolox, the TEAC values decrease with increasing concentrations of the compounds for each measuring time, and increase with increasing measuring times for each concentration. In the present study, we conclude that, in order to evaluate relative antioxidant activities of compounds by the ABTS assay, it is essential to perform kinetic studies to assess scavenging of ABTS?+ by these compounds. Therefore, when the TEAC values of compounds are determined for more than one measuring time, we may be sure that all the antioxidant potential of compounds is being considered and whether or not it is possible to establish a hierarchy for their antioxidant activities. 相似文献
6.
Lichenometry is used to date late-Holocene terminal moraines that record glacier fluctuations. Traditionally, it relies upon
dating curves that relate diameters of the largest lichens in a population to surface ages. Although widely used, the technique
remains controversial, in part because lichen biology is poorly understood. We use size-frequency distributions of lichens
growing on well-dated surfaces to fit demographic models for Rhizocarpon geographicum and Pseudophebe pubescens, two species commonly used for lichenometry. We show that both species suffer from substantial mortality of 2–3% per year,
and grow slowest when young-trends that explain a long-standing contradiction between the literatures of lichenometry and
lichen biology. Lichenometrists interpret the shape of typical dating curves to indicate a period of rapid juvenile “great
growth,” contrary to the growth patterns expected by biologists. With a simulation, we show how the “great growth” pattern
can be explained by mortality alone, which ensures that early colonists are rarely found on the oldest surfaces. The consistency
of our model predictions with biological theory and observations, and with dozens of lichenometric calibration curves from
around the world, suggests opportunities to assess quantitatively the accuracy and utility of this common dating technique. 相似文献
7.
Babita Paudel Hari Datta Bhattarai Jin Sung Lee Soon Gyu Hong Hyun Woung Shin Joung Han Yim 《Polar Biology》2008,31(5):605-608
Antioxidant agents prevent reactive oxygen species, which can cause degenerative diseases. Natural antioxidants are preferred
over many synthetic antioxidants, which can be toxic, for therapeutic applications. Five lichen species were collected from
King George Island, Antarctica. Antioxidant activities as assessed by DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical and
ABTS•+ [2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonate)] radical scavenging capacities were determined and compared with those
of commercial standards BHA (butylated hydroxyanisole) and trolox [(±)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic
acid]. The results indicated that two lichens exhibited comparatively high antioxidant activities with the remaining three
exhibiting less activity. The antioxidant activity was concentration-dependent. When compared, the antioxidant activity of
crude extracts from polar lichens to previously published data for tropical and temperate lichen species, we concluded that
lichens of Antarctic origin may be the potent sources of strong antioxidant agents. Such species should be explored as novel
sources of effective antioxidant metabolites. 相似文献
8.
Scavenging of the ABTS (2,2′-azinobis[3-ethylbenzothiazoline-6-sulphonate])-derived nitrogen-centred radical cation (ABTS?+) was used to compare the total antioxidant activities of several seasonings used in Asian cooking. The results were expressed as Trolox equivalent antioxidant capacity (TEAC). The TEAC activities of dark soy sauces were found to be exceptionally high. In evaluating the TEAC of commercial products, attention must be paid to the addition of preservatives by manufacturers to the seasonings tested. Sodium benzoate (a preservative added to several seasonings) did not react significantly with ABTS?+, but the sulphite content of certain white wines may have led to an over-estimation of their TEAC. 相似文献
9.
Mira L Silva M Rocha R Manso CF 《Redox report : communications in free radical research》1999,4(1-2):69-74
The relative activities of some hydrogen-donating antioxidants were assessed by comparing their activities with that of Trolox (Trolox equivalent antioxidant capacity, TEAC) for scavenging the ABTS radical cation (ABTS.+) generated in the aqueous phase. We have verified, however, that TEAC values may change with the concentration of compounds and with the measuring times used. Not withstanding, TEAC values do not differ significantly if the compounds have kinetic curves of ABTS.+ formation similar to that of Trolox. This is the case with ascorbic acid, whose TEAC values, determined by using five concentrations at three different measuring times, are very close. For the flavonoids studied (catechin, rutin, naringenin and silibinin) which have kinetic curves of ABTS.+ formation different from that of Trolox, the TEAC values decrease with increasing concentrations of the compounds for each measuring time, and increase with increasing measuring times for each concentration. In the present study, we conclude that, in order to evaluate relative antioxidant activities of compounds by the ABTS assay, it is essential to perform kinetic studies to assess scavenging of ABTS.+ by these compounds. Therefore, when the TEAC values of compounds are determined for more than one measuring time, we may be sure that all the antioxidant potential of compounds is being considered and whether or not it is possible to establish a hierarchy for their antioxidant activities. 相似文献
10.
Antonella Smeriglio Valeria D'Angelo Marcella Denaro Domenico Trombetta Francesco Maria Raimondo Maria Paola German 《化学与生物多样性》2019,16(9)
In this study, we investigated the phenolic composition of the crude extract (MeOH 80 %) of Alnus cordata (Loisel .) Duby stem bark (ACE) and its antioxidant and skin whitening properties. RP‐LC‐DAD analysis showed a high content of hydroxycinnamic acids (47.64 %), flavanones (26.74 %) and diarylheptanoids (17.69 %). Furthermore, ACE exhibited a dose‐dependent antioxidant and free‐radical scavenging activity, expressed as half‐maximal inhibitory concentration (IC50): Oxygen radical absorbance capacity (ORAC, IC50 1.78 μg mL?1)>Trolox equivalent antioxidant capacity (TEAC, IC50 3.47 μg mL?1)>2,2‐Diphenyl‐1‐picrylhydrazyl (DPPH, IC50 5.83 μg mL?1)>β‐carotene bleaching (IC50 11.58 μg mL?1)>Ferric reducing antioxidant power (FRAP, IC50 17.28 μg mL?1). Moreover, ACE was able to inhibit in vitro tyrosinase activity (IC50 77.44 μg mL?1), l ‐DOPA auto‐oxidation (IC50 39.58 μg mL?1) and in an in vivo model it exhibited bleaching effects on the pigmentation of zebrafish embryos (72 h post fertilization) without affecting their development and survival. In conclusion, results show that A. cordata stem bark may be considered a potential source of agents for the treatment of skin disorders due to its bleaching properties and favorable safety profiles, associated to a good antioxidant power. 相似文献
11.
Anna R. Proteggente Ananth Sekher Pannala George Paganga Leo van Buren Eveline Wagner Sheila Wiseman 《Free radical research》2013,47(2):217-233
Recent studies are emphasising the importance and putative modes of action of specific flavonoids as bioactive components of the diet in in vivo and in vitro models. Thus, it is important to have a clear idea of the major phenolic families of which fruit and vegetables are comprised and the levels contained therein. Regularly consumed fruit and vegetables of mixed varieties available on the UK market were analysed for the composition of the major individual phenolic components. The total phenolic content (applying the Folin assay) and the vitamin C levels were also determined. The antioxidant capacities of aqueous/methanolic extracts were comparatively assessed using the TEAC (Trolox Equivalent Antioxidant Capacity), the FRAP (Ferric Reducing Ability of Plasma) and ORAC (Oxygen Radical Absorbance Capacity) assays, which comprise contributions from polyphenols, simple phenols and the ascorbate component. The results were calculated in terms of 100 u g fresh weight (FW) uncooked portion sizes. Fruit and vegetables rich in anthocyanins (e.g. strawberry, raspberry and red plum) demonstrated the highest antioxidant activities, followed by those rich in flavanones (e.g. orange and grapefruit) and flavonols (e.g. onion, leek, spinach and green cabbage), while the hydroxycinnamate-rich fruit (e.g. apple, tomato, pear and peach) consistently elicited the lower antioxidant activities. The TEAC, FRAP and ORAC values for each extract were relatively similar and well-correlated with the total phenolic and vitamin C contents. The antioxidant activities (TEAC) in terms of 100 u g FW uncooked portion size were in the order: strawberry d raspberry=red plum d red cabbage>>>grapefruit= orange>spinach>broccoli>green grape ; onion> green cabbage>pea>apple> cauliflower ; pear> tomato ; peach=leek>banana ; lettuce. 相似文献
12.
William B. Collins Bruce W. Dale Layne G. Adams Darien E. Mcelwain Kyle Joly 《The Journal of wildlife management》2011,75(2):369-377
In the early 1990s the Nelchina Caribou (Rangifer tarandus) Herd (NCH) began a dramatic shift to its current winter range, migrating at least an additional 100 km beyond its historic range. We evaluated the impacts of fire and grazing history on lichen abundance and subsequent use and distribution by the NCH. Historic (prior to 1990) and current (2002) winter ranges of the NCH had similar vascular vegetation, lichen cover (P = 0.491), and fire histories (P = 0.535), but the former range had significantly less forage lichen biomass as a result of grazing by caribou. Biomass of forage lichens was twice as great overall (P = 0.031) and 4 times greater in caribou selected sites on the current range than in the historic range, greatly increasing availability to caribou. Caribou on the current range selected for stands with >20% lichen cover (P < 0.001), greater than 1,250 kg/ha (P < 0.001) forage lichen biomass and stands older than 80 yr postfire (P < 0.001). After fires, forage lichen cover and biomass seldom recovered sufficiently to attract caribou grazing until after ≥60 yr, and, as a group, primary forage lichen species did not reach maximum abundance until 180 yr postfire. Recovery following overgrazing can occur much more quickly because lichen cover, albeit mostly fragments, and organic substrates remain present. Our results provide benchmarks for wildlife managers assessing condition of caribou winter range and predicting effects of fires on lichen abundance and caribou distribution. Of our measurements of cover and biomass by species, densities and heights of trees, elevation, slope and aspect, only percentage cover by Cladonia amaurocraea, Cladina rangiferina, Flavocetraria cuculata, and lowbush cranberry (Vaccinium vitis-idaea) were necessary for predicting caribou use of winter range. © 2011 The Wildlife Society 相似文献
13.
Alejandro Betancor-Fernandez Helmut Sies Wilhelm Stahl M. Cristina Polidori 《Free radical research》2013,47(8):915-921
2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman ( f -CEHC) has been identified as a major water-soluble metabolite of vitamin E, which circulates in the blood and is excreted with the urine. The aim of this study was to assess the antioxidant activity of f -CEHC using several methods with different prooxidant challenges. In the Oxygen Radical Absorbance Capacity assay, a fluorescent protein acts as a marker for oxidative damage induced by peroxyl radicals. In the Trolox Equivalent Antioxidant Capacity (TEAC) assay, a stable free radical, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS ” + ) is reduced directly by antioxidants. Scavenging properties vs. reactive nitrogen species were studied measuring the effects on tyrosine nitration after reaction with peroxynitrite. Trolox, f -tocopherol, ascorbic acid, and ( m )-epicatechin were simultaneously tested in order to compare their antioxidant activities. In all mentioned systems, f -CEHC exhibited antioxidant properties similar to those of Trolox. We conclude that f -CEHC is a molecule with good antioxidant activity, having the advantage over Trolox of being a naturally occurring compound. These properties might be useful for research or industrial purposes. 相似文献
14.
Echinochrome A (6-ethyl-2,3,5,7,8-pentahydroxy-1,4-naphthoquinone) isolated from the body of sand dollar Scaphechinus mirabilis is an active substance of cardioprotective medication Histochrome and exerts a wide spectrum of anti-inflammatory activities. In the present paper, we conducted a comparative study of the antioxidant (radical-scavengering) properties of echinochrome A in 2,2′-azobis(2-methylpropionamidine) dihydrochloride?luminol and hemoglobin?hydrogen peroxide?luminol systems and assessed its impact on permeability of planar bilayer lipid membranes. Trolox was used as a reference antioxidant and ascorbic acid and dihydroquercetin are taken as standards. Echinochrome A shows moderate antioxidant activity, possessing higher antioxidant capacity than Trolox and ascorbic acid, but exhibiting lower antioxidant potential compared with dihydroquercetin in tests for antioxidant activity in both investigated systems. The test substances can be arranged in the following order according to the effectiveness of the antioxidant effect: dihydroquercetin > echinochrome A > Trolox > ascorbic acid. Echinochrome A does not lead to significant changes in the permeability of planar bilayer membranes in a dose range of 1.5 to 30 μМ. Our data indicate that echinochrome A has a rather high level of radical-scavengering activity without a primary membranotropic effect. It is thought that the high levels of the cardioprotective and anti-inflammatory activities of echinochrome A may be due not only to the ability of this substance to neutralize reactive oxygen species, but also to its capacity to generate physiological concentrations of hydrogen peroxide molecules in biological systems as signaling messengers of various metabolic processes and biochemical pathways. The suspected mechanisms of the biological activity of echinochrome A are discussed. 相似文献
15.
Mohamed Mendili Marwa Bannour Maria Eduarda M. Araújo Mark R. D. Seaward Ayda Khadhri 《化学与生物多样性》2021,18(2):e2000735
The phenolic composition and antioxidant capacity of four Tunisian lichen species, Cladonia rangiformis, Flavoparmelia caperata, Squamarina cartilaginea and Xanthoria parietina, were determined in order to provide a better understanding of their lichenochemical composition. Powdered material of F. caperata was the richest in total phenolic content (956.68 μg GAE g−1 DW) and S. cartilaginea in proanthocyanidin content (77.31 μg CE g−1 DW), while the acetone extract of X. parietina showed the highest flavonoid content (9.56 μg CE g−1 DW). The antioxidant capacity of all lichen extracts and crude material was evaluated by DPPH. scavenging, iron-chelating, and iron-reducing powers. Results showed that methanol extracts of S. cartilaginea had the highest DPPH. antioxidant capacity (IC50=0.9 μg mL−1) and the highest iron-reducing power was attributed to the acetone extract of this species. All extracts of all species were further screened by Fourier-transform infrared spectroscopy (FT-IR) and nuclear resonance spectroscopy (NMR); results showed an abundance of phenols, aromatic compounds, and fatty acids. Overall, our results showed that the investigated species are a rich source of potentially bioactive compounds with valuable properties. 相似文献
16.
The antioxidant activities of seasonings used in Asian cooking. Powerful antioxidant activity of dark soy sauce revealed using the ABTS assay 总被引:1,自引:0,他引:1
Scavenging of the ABTS (2,2'-azinobis[3-ethylbenzothiazoline-6-sulphonate])-derived nitrogen-centred radical cation (ABTS•+) was used to compare the total antioxidant activities of several seasonings used in Asian cooking. The results were expressed as Trolox equivalent antioxidant capacity (TEAC). The TEAC activities of dark soy sauces were found to be exceptionally high. In evaluating the TEAC of commercial products, attention must be paid to the addition of preservatives by manufacturers to the seasonings tested. Sodium benzoate (a preservative added to several seasonings) did not react significantly with ABTS•+, but the sulphite content of certain white wines may have led to an over-estimation of their TEAC. 相似文献
17.
Maria Pia Rigobello Roberto Stevanato Federico Momo Sabrina Fabris Guido Scutari Rita Boscolo 《Free radical research》2013,47(3):315-321
Propofol (2,6-diisopropylphenol), some substituted phenols (2,6-dimethylphenol and 2,6-ditertbutylphenol) and their 4-nitrosoderivatives have been compared for their scavenging ability towards 1,1-diphenyl-2-picrylhydrazyl and for their inhibitory action on lipid peroxidation. These products were also compared to the classical antioxidants butylated hydroxytoluene and butylated hydroxyanisole. When measuring the reactivity of the various phenolic derivatives with 1,1-diphenyl-2-picrylhydrazyl the following order of effectiveness was observed: butylated hydroxyanisole>propofol>2,6-dimethylphenol>2,6-di-tertbutylphenol?>?butylated hydroxytoluene. In cumene hydroperoxide-dependent microsomal lipid peroxidation, propofol acts as the most effective antioxidant, while butylated hydroxyanisole, 2,6-di-tertbutylphenol and butylated hydroxytoluene exhibit a rather similar effect, although lower than propofol. In the iron/ascorbate-dependent lipid peroxidation propofol, at concentrations higher than 10?μM, exhibits antioxidant properties comparable to those of butylated hydroxytoluene and butylated hydroxyanisole. 2,6-Dimethylphenol is scarcely effective in both lipoperoxidative systems. The antioxidant properties of the various molecules depend on their hydrophobic characteristics and on the steric and electronic effects of their substituents. However, the introduction of the nitroso group in the 4-position almost completely removes the antioxidant properties of the examined compounds. The nitrosation of the aromatic ring of antioxidant molecules and the consequent loss of antioxidant capacity can be considered a condition potentially occurring in vivo since nitric oxide and its derivatives are continuously formed in biological systems. 相似文献
18.
Antioxidant activities and phenolics content of eight species of seaweeds from north Borneo 总被引:1,自引:0,他引:1
Patricia Matanjun Suhaila Mohamed Noordin Mohamed Mustapha Kharidah Muhammad Cheng Hwee Ming 《Journal of applied phycology》2008,20(4):367-373
The antioxidant activity of eight edible species of Malaysian North Borneo seaweeds obtained from Sabah waters (Kudat, Tanjung
Aru and Semporna) consisting of three red seaweeds (Eucheuma cottonii, E. spinosum and Halymenia durvillaei), two green seaweeds (Caulerpa lentillifera and C. racemosa) and three brown seaweeds (Dictyota dichotoma, Sargassum polycystum and Padina sp.) were determined. Methanol and diethyl ether were used as extraction solvent. The antioxidant activities were determined
by two methods, TEAC (trolox equivalent antioxidant capacity) and FRAP (ferric reducing antioxidant power) assays. The total
phenolic content of the extract was determined according to the Folin–Ciocalteu method and results were expressed as phloroglucinol
equivalents. The methanolic extracts of green seaweeds, C. lentillifera and C. racemosa, and the brown seaweed, S. polycystum showed better radical-scavenging and reducing power ability, and higher phenolic content than the other seaweeds. The TEAC
and FRAP assays showed positive and significantly high correlation (R
2 = 0.89). There was a strong correlation (R
2 = 0.96) between the reducing power and the total phenolic content of the seaweeds methanolic dry extracts. These seaweeds
could be potential rich sources of natural antioxidants. 相似文献
19.
Question: Does the neophyte moss Campylopus introflexus invade more often in drift sand pioneer vegetations under high nitrogen (N) deposition? Location: Fourteen inland dune reserves in The Netherlands over a gradient of atmospheric N deposition. Methods: A transect study, dispersal experiment and culture experiment were carried out. In the transect study, the establishment of C. introflexus and lichens was measured in pure mats of Polytrichum piliferum, an early succession stage. The overall presence of C. introflexus in the area was also estimated. In the dispersal experiment, fragments of C. introflexus and lichen species were sown in P. piliferum mats at two sites with high and low N deposition. In the culture experiment C. introflexus fragments were grown on soil with different carbon (C) content and N dose. Results: The Campylopus:lichen ratio was positively correlated (r2=0.61) with the atmospheric ammonia concentration. Campylopus began to dominate at an ammonia air concentration of 7 μg m?3, correlated with the overall presence of the species in the sites investigated. Survival of sown Campylopus fragments was significantly higher and the endangered lichen Cladonia strepsilis significantly lower in the site with a high ammonia concentration. Survival of Cladonia coccifera and Cladonia portentosa was high at both sites. Experimental growing of C. introflexus showed significant responses to both C content and N, although C content showed the strongest effect. Conclusions: Growth of C. introflexus is affected by soil C content and N deposition. Inland dune reserves under high N deposition risk loss of lichen‐dominated vegetations because of moss encroachment. 相似文献
20.
红花桑寄生叶提取物的抗氧化活性及酚类物质分析 总被引:4,自引:0,他引:4
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。 相似文献