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1.
Sequestration of Furostanol Saponins by <Emphasis Type="Italic">Monophadnus</Emphasis> Sawfly Larvae
Prieto JM Schaffner U Barker A Braca A Siciliano T Boevé JL 《Journal of chemical ecology》2007,33(3):513-524
Sawfly larvae of the tribe Phymatocerini (Hymenoptera: Tenthredinidae), which are specialized on toxic plants in the orders
Liliales and Ranunculales, exude a droplet of deterrent hemolymph upon attack by a predator. We investigated whether secondary
plant metabolites from Ranunculaceae leaves are sequestered by phymatocerine Monophadnus species, i.e., Monophadnus alpicola feeding upon Pulsatilla alpina and Monophadnus monticola feeding upon Ranunculus lanuginosus. Moreover, two undescribed Monophadnus species were studied: species A collected from Helleborus foetidus and species B collected from Helleborus viridis. Comparative high-performance liquid chromatographic–photodiode array detection–electrospray ionization–mass spectrometric
analyses of plant leaf and insect hemolymph extracts revealed the presence of furostanol saponins in all samples. Larvae of
species A and B actively sequestered (25R)-26-[(α-l-rhamnopyranosyl)oxy]-22α-methoxyfurost-5-en-3β-yl O-β-d-glucopyranosyl-(1→3)-O-[6-acetyl-β-d-glucopyranosyl-(1→3)]-O-β-d-glucopyranoside (compound 1). This compound occurred at a 65- to 200-fold higher concentration in the hemolymph of the two species (1.6 and 17.5 μmol/g
FW, respectively) than in their host plant (0.008 and 0.268 μmol/g FW, respectively). In M. monticola, compound 1 was found at a concentration (1.2 μmol/g FW) similar to that in the host plant (1.36 μmol/g FW). The compound could not be
detected consistently in M. alpicola larvae where, however, a related saponin may be present. Additional furostanol saponins were found in H. foetidus and H. viridis, but not in the two Monophadnus species feeding on them, indicating that sequestration of compound 1 is a highly specific process. In laboratory bioassays, crude hemolymph of three Monophadnus species showed a significant feeding deterrent activity against a potential predator, Myrmica rubra ant workers. Isolated furostanol saponins were also active against the ants, at a concentration range similar to that found
in the hemolymph. Thus, these compounds seem to play a major role for chemical defense of Monophadnus larvae, although other plant secondary metabolites (glycosylated ecdysteroids) were also detected in their hemolymph. Physiological
and ecological implications of the sequestered furostanol saponins are discussed.
Dedicated to the memory of Professor Ivano Morelli (1940–2005) 相似文献
2.
Vivek K. Bajpai Nguyen Thi Dung Hwa-Jin Suh Sun Chul Kang 《Journal of the American Oil Chemists' Society》2010,87(11):1341-1349
This study was undertaken to assess the antibacterial efficacy of the essential oil and extracts of Cleistocalyx operculatus buds against plant pathogenic bacteria of Xanthomonas spp. The diameter of inhibition zones of oil (1,000 μg/disc) and extracts (1,500 μg/disc) against the tested bacteria were
found in the range of 7–23 mm. The MIC and MBC values of the oil and extracts against the tested Xanthomonas spp. ranged from 31.25–125 to 62.5–250 μg/ml and 125–500 and 250–1,000 μg/ml, respectively. The cell viability study demonstrated
a potential detrimental effect of the oil (1,000 μg/ml) and hexane extract (250 μg/ml) on the tested Xanthomonas spp. Also the oil displayed significant antibacterial effects in vivo against Xoo KX019 and Xsp SK12 conducted on greenhouse-grown oriental melon plants (Cucumis melo L. var. makuwa). The results of this study suggest that C. operculatus-derived essential oil and extracts could be used as natural bactericides in the food and agriculture industries. 相似文献
3.
Fredric V. Vencl Nélida E. Gómez Kerstin Ploss Wilhelm Boland 《Journal of chemical ecology》2009,35(3):281-288
Larval insect herbivores feeding externally on leaves are vulnerable to numerous and varied enemies. Larvae of the Neotropical
herbivore, Chelymorpha alternans (Chrysomelidae:Cassidinae), possess shields made of cast skins and feces, which can be aimed and waved at attacking enemies.
Prior work with C. alternans feeding on Merremia umbellata (Convolvulaceae) showed that shields offered protection from generalist predators, and polar compounds were implicated. This
study used a ubiquitous ant predator, Azteca lacrymosa, in field bioassays to determine the chemical constitution of the defense. We confirmed that intact shields do protect larvae
and that methanol-water leaching significantly reduced shield effectiveness. Liquid chromatography-mass spectrometry (LC-MS)
of the methanolic shield extract revealed two peaks at 20.18 min and 21.97 min, both with a molecular ion at m/z 593.4, and a strong UV absorption around 409 nm, suggesting a porphyrin-type compound. LC-MS analysis of a commercial standard
confirmed pheophorbide a (Pha) identity. C. alternans shields contained more than 100 μg Pha per shield. Shields leached with methanol-water did not deter ants. Methanol-water-leached shields enhanced with 3 μg of
Pha were more deterrent than larvae with solvent-leached shields, while those with 5 μg additional Pha provided slightly less deterrence than larvae with intact shields. Solvent-leached shields with 10 μg added Pha were comparable to intact shields, even though the Pha concentration was less than 10% of its natural concentration. Our findings are the first to assign an ecological role for
a chlorophyll catabolite as a deterrent in an insect defense. 相似文献
4.
Y. C. Mitei J. C. Ngila S. O. Yeboah L. Wessjohann J. Schmidt 《Journal of the American Oil Chemists' Society》2009,86(7):617-625
The phytosterol, tocopherol, and tocotrienol profiles for mkukubuyo, Sterculia africana, manketti, Ricinodendron rautanenni, mokolwane, Hyphaene petersiana, morama, Tylosema esculentum, and moretologa-kgomo, Ximenia caffra, seed oils from Botswana have been determined. Normal-phase HPLC analysis of the unsaponifiable matter showed that among the
selected oils, the most abundant tocopherol and tocotrienol were γ-tocopherol (2232.99 μg/g) and γ-tocotrienol (246.19 μg/g),
detected in manketti and mkukubuyo, respectively. Mokolwane oil, however, contained the largest total tocotrienol (258.47 μg/g).
Total tocol contents found in manketti, mokolwane, mkukubuyo, morama, and moretologa-kgomo oils were 2238.60, 262.40, 246.20,
199.10, and 128.0 μg/g, respectively. GC–MS determination of the relative percentage composition of phytosterols showed 4-desmethylsterols
as the most abundant phytosterols in the oils, by occurring up to 90% in moretologa-kgomo, mkukubuyo, and manketti seed oils,
with β-sitosterol being the most abundant. Mokolwane seed oil contained the largest percentage composition of 4,4-dimethylsterols
(45.93%). Besides 4-desmethylsterols (75%), morama oil also contained significant amounts of 4,4-dimethylsterols and 4-monomethylsterols
(15.72% total). GC–MS determination of the absolute amounts of 4-desmethylsterols, after SPE fractionation of the unsaponifiable
matter, confirmed that β-sitosterol was the most abundant phytosterol in the test seed oils, with manketti seed oil being
the richest source (1326.74 μg/g). The analysis showed total 4-desmethylsterols content as 1617.41, 1291.88, 861.47, 149.15,
and 109.11 μg/g for manketti, mokolwane, mkukubuyo, morama, and moretologa-kgomo seed oils, respectively. 相似文献
5.
Sarojini J. K. A. Ubhayasekera Alba Tres Rafael Codony Paresh C. Dutta 《Journal of the American Oil Chemists' Society》2010,87(2):173-184
Chicken is the most widely consumed meat all over the world due to chickens being easy to rear, their fast growth rate and
the meat having good nutritional characteristics. The main objective of this paper was to study the effects of dietary fatty
by-products in low, medium and high levels of oxidized lipids and trans fatty acids (TFAs) on the contents of cholesterol and oxycholesterols in meat, liver, and plasma of chickens. A palm fatty
acid distillate, before and after hydrogenation, and a sunflower–olive oil blend (70/30, v/v) before and after use in a commercial
frying process were used in feeding trials after adding 6% of the fats to the feeds. Highly oxidized lipid and TFA feeds significantly
increased the contents of cholesterol and oxycholesterols in all tissues of chicken (0.01 < p ≤ 0.05). The contents of oxycholesterols in chicken meat, liver and plasma obtained from TFA feeding trials varied between
17 and 48 μg/100 g in meat, 19–42 μg/100 g in liver and 105–126 μg/dL in plasma. In contrast, in the oxidized lipid feeding
trials, oxycholesterols varied between 13 and 75 μg/100 g in meat, 30–58 μg/100 g in liver and 66–209 μg/dL in plasma. Meat
from chickens fed with feeds containing high levels of TFAs or oxidized lipids may contribute to higher ingestion of cholesterol
and oxycholesterols by humans. 相似文献
6.
The toxic effect of hypericin (HYP), a photodynamic quinone that occurs in certain species of the genusHypericum, towardsManduca sexta third-instar larvae was investigated. The LD50 of purified hypericin was 16 g/g larval initial fresh weight in constant light (22 W/m2). Reduced irradiance resulted in decreased mortality. Sublethal applications retarded larval growth (body fresh weight) in a dose-dependent manner. Toxicity had an absolute light dependence at the dose levels used, the active wavelengths being >500 nm. The phototoxic effect was rapidly lost when larvae were maintained in darkness (>8 hr) prior to irradiation. However, the potential for light-dependent mortality was retained if larvae were starved prior to irradiation. 相似文献
7.
Plant diseases constitute an emerging threat to global food security. Many of the currently available antifungal agents for
agriculture are highly toxic and nonbiodegradable and cause extensive environmental pollution. Moreover, an increasing number
of phytopathogens are developing resistance to them. Therefore, the aim of this study was to assess the antifungal efficacy
of the leaf essential oil and the leaf extracts of Metasequoia glyptostroboides against Fusarium oxysporum, Fusarium solani, Phytophthora capsici, Colletotrichum capsici, Sclerotinia sclerotiorum, Botrytis cinerea and Rhizoctonia solani. The oil (1,000 μg/disc) and the extracts (1,500 μg/disc) revealed a remarkable antifungal effect against the tested plant
pathogenic fungi with a radial growth inhibition percentage of 41.3–66.3% and 13.4–54.4%, respectively along with their respective
MIC values ranging from 62.5 to 1,000 μg/ml and 500–4,000 μg/ml. The oil had a strong detrimental effect on spore germination
of all the tested plant pathogens along with the concentration as well as time-dependent kinetic inhibition of Botrytis cinerea. Also, the oil exhibited a potent in vivo antifungal effect against Phytophthora capsici on greenhouse grown pepper plants. The results of this study indicate that the oil and extracts of M. glyptostroboides leaves could become natural alternatives to synthetic fungicides to control certain important plant fungal diseases. 相似文献
8.
Samir A. M. Abdelgaleil Magdy I. E. Mohamed Mohamed E. I. Badawy Sailan A. A. El-arami 《Journal of chemical ecology》2009,35(5):518-525
A comparative study was conducted to assess the contact and fumigant toxicities of eleven monoterpenes on two important stored
products insects—, Sitophilus oryzae, the rice weevil, and Tribolium castaneum, the rust red flour beetle. The monoterpenes included: camphene, (+)-camphor, (−)-carvone, 1-8-cineole, cuminaldehyde, (l)-fenchone, geraniol, (−)-limonene, (−)-linalool, (−)-menthol, and myrcene. The inhibitory effect of these compounds on acetylcholinesterase
(AChE) activity also was examined to explore their possible mode(s) of toxic action. Although most of the compounds were toxic
to S. oryzae and T. castaneum, their toxicity varied with insect species and with the bioassay test. In contact toxicity assays, (−)-carvone, geraniol,
and cuminaldehyde showed the highest toxicity against S. oryzae with LC50 values of 28.17, 28.76, and 42.08 μg/cm2, respectively. (−)-Carvone (LC50 = 19.80 μg/cm2) was the most effective compound against T. castaneum, followed by cuminaldehyde (LC50 = 32.59 μg/cm2). In contrast, camphene, (+)-camphor, 1-8-cineole, and myrcene had weak activity against both insects (i.e., LC50 values above 500 μg/cm2). In fumigant toxicity assays, 1-8-cineole was the most effective against S. oryzae and T. castaneum (LC50 = 14.19 and 17.16 mg/l, respectively). Structure-toxicity investigations revealed that (−)-carvone—, a ketone—, had the highest
contact toxicity against the both insects. 1-8-Cineole—, an ether—, was the most potent fumigant against both insects. In
vitro inhibition studies of AChE from adults of S. oryzae showed that cuminaldehyde most effectively inhibited enzyme activity at the two tested concentrations (0.01 and 0.05 M) followed
by 1-8-cineole, (−)-limonene, and (l)-fenchone. 1-8-Cineole was the most potent inhibitor of AChE activity from T. castaneum larvae followed by (−)-carvone and (−)-limonene. The results of the present study indicate that (−)-carvone, 1,8-cineole,
cuminaldehyde, (l)-fenchone, and (−)-limonene could be effective biocontrol agents against S. oryzae and T. castaneum. 相似文献
9.
Concentrations of soluble phenolics and lignin in the phloem of ponderosa pines inoculated with the pathogen Heterobasidion annosum were assessed over a period of 2 years in a 35-year-old plantation in northern California, USA. The major effect of the pathogen on phloem-soluble phenolics consisted of a significant accumulation of ferulicacid glucoside: 503 ± 27 g/g fresh weight (FW), compared with 366 ± 26 g/g FW for mock-treated and 386 ± 27 g/g FW for control trees. Lignin content was negatively correlated with ferulic acid glucoside concentration, and there was an indication of lignin reduction in the cell walls of inoculated trees. Lignin had a negative effect on the in vitro growth of two common bark beetle fungal associates, Ceratocystiopsis brevicomi and Ophiostoma minus. For this reason it, is hypothesized that lower lignification may facilitate the growth of beetle-associated fungi, resulting in greater susceptibility of the presymptomatic host to bark beetle colonization. 相似文献
10.
Qun Li Sanford D. Eigenbrode G. R. Stringam M. R. Thiagarajah 《Journal of chemical ecology》2000,26(10):2401-2419
We measured feeding behavior, feeding damage, and larval growth of the crucifer specialist, Plutella xylostella and the generalist, Spodoptera eridania, on the cotyledons of 14 homozygous lines of Brassica juncea differing in myrosinase activity and glucosinolate profiles. The proportion of time feeding and area damaged by P. xylostella were lower on lines with high myrosinase activities [0.49–0.73 nmol glucose released/mg tissue(fresh weight, FW)/min] than on lines with low myrosinase activities [0.20–0.31 nmol glucose released/mg tissue(FW)/min]. In contrast, the proportion of time feeding and area damaged by S. eridania were not related to myrosinase activity, but were lower on cotyledons of lines with high glucosinolate concentrations [6.8–21.3 g/g(FW)] than on lines with low glucosinolate concentrations [0.09–0.61 g/g(FW)]. Relative growth rates (RGR) of both insect species were lower on lines with high glucosinolate concentrations, but were not related to myrosinase activity in the lines. In toxicity experiments that used artificial diets, allyl isothiocyanate, but not allyl glucosinolate, was lethally toxic to neonate P. xylostella (LC50s of 1.54 mol/g, and 100 mol/g, respectively), whereas isothiocyanate and the glucosinolate were lethally toxic to neonate S. eridania (LC50s of 3.42 and 6.73 mol/g, respectively). We interpret these results to indicate that myrosinase activity might be more important for plant defense against specialist insects that have adaptations to intact glucosinolates, but less important for defense against generalists, which are susceptible to the intact glucosinolates. 相似文献
11.
Sung Dong Lee Guijae Yoo Hee Jeong Chae Man-Jin In Nam-Soon Oh Yoon Kyung Hwang Woo Ik Hwang Dong Chung Kim 《Journal of the American Oil Chemists' Society》2009,86(11):1065-1071
The anticancer activity of ginseng originated mainly from lipid-soluble components. The hexane extract of ginseng marc (HEGM)
showed a potent inhibitory activity on human hepatoma (HepG2, GI50 = 41.7 μg/ml) and breast (MCF-7, GI50 = 54.4 μg/ml) cancer cell proliferation in vitro in a concentration-dependent manner as did the hexane extract of ginseng
(HEG), with GI50 values of 21.1 μg/ml in HepG2 and 41.2 μg/ml in MCF-7. The water extract of ginseng (WEG) possessed a low anticancer activity
against both cancer cell lines, but the hexane-soluble fraction of WEG (HSF/WEG) showed a potent anticancer activity against
HepG2 (GI50 = 38.7 μg/ml) and MCF-7 cells (GI50 = 51.1 μg/ml). The hexane extraction in ginseng was a very promising protocol for the maximum recovery of the anticancer
active components in high concentrations. Also the adoption of hexane extraction after water extraction of ginseng was successful
in the effective utilization of the residual lipid-soluble anticancer active components in ginseng marc. 相似文献
12.
To investigate the heat induced formation of α,β-unsaturated 4-hydroxy-aldehydes (4-hydroxy-2-trans-hexenal (HHE), 4-hydroxy-2-trans-octenal (HOE), 4-hydroxy-2-trans-nonenal (HNE) and 4-hydroxy-2-trans-decenal (HDE)) fatty acid methyl esters (FAMEs) of stearic, oleic, linoleic and linolenic acids were heated separately at
185°C for 0 to 6 hrs. The formation of 2,4-decadienal, a suspected intermediate in HNE formation, was also measured in these
FAMEs. As expected methyl stearate (MS) and methyl oleate (MO) did not produce any of the α,β-unsaturated 4-hydroxy-aldehydes
as a consequence of thermally induced lipid peroxidation. The formation of HHE was detected in both methyl linoleate (ML)
and methyl linolenate (MLN), with concentration higher in MLN than in ML. The maximum HHE concentration was 3.99 μg HHE/g
ML after 2 h and 50.78 μg HHE/g MLN after 4 h of heat treatment. HOE was detected in both ML and MLN, and the maximum concentration
was 102.50 μg HOE/g ML after 6 h and 90.56 μg HOE/g MLN after 2 h of heating. HNE was found only in ML and its highest concentration
was 84.82 μg HNE/g ML after 3 h of heating. HDE was not detected in any of the four heat treated FAMEs. 2,4-Decadienal was
not found to be an intermediate in the formation of HNE in thermally induced oxidation of FAMEs. 相似文献
13.
Antimicrobial Activity of Essential Oils Isolated from Phlomis crinita Cav. ssp. mauritanica Munby 总被引:1,自引:0,他引:1
Ilef Limem-Ben Amor Aicha Neffati Mohamed Ben Sgaier Wissem Bhouri Jihed Boubaker Ines Skandrani Ines Bouhlel Soumaya Kilani Rebai Ben Ammar Imed Chraief Mohamed Hammami Mohamed Ghoul Leila Chekir-Ghedira Kamel Ghedira 《Journal of the American Oil Chemists' Society》2008,85(9):845-849
The essential oil extracted from the leaves and flowers of Phlomis crinita Cav. ssp. mauritanica Munby were obtained by steam distillation and analyzed by gas chromatography coupled with mass spectrometry. The major constituents
of flower oil were β-caryophyllene (58.1%) and germacrene D (35.1%). This oil inhibited the growth of Staphylococcus aureus, Enterococcus faecalis, and Salmonella typhimurium with minimal inhibition concentrations (MIC) varying between 39 and 625 μg/ml. The essential oil obtained from the leaves
was mainly composed of trans-caryophyllene (40.8%) and germacrene D (39.1%) and exhibited an antimicrobial profile against the same strains mentioned
above with MIC between 156 μg/ml and 2.5 mg/ml. 相似文献
14.
James V. Rogers Christopher V. Parkinson Young W. Choi Janice L. Speshock Saber M. Hussain 《Nanoscale research letters》2008,3(4):129-133
The use of nanotechnology and nanomaterials in medical research is growing. Silver-containing nanoparticles have previously
demonstrated antimicrobial efficacy against bacteria and viral particles. This preliminary study utilized an in vitro approach
to evaluate the ability of silver-based nanoparticles to inhibit infectivity of the biological select agent, monkeypox virus
(MPV). Nanoparticles (10–80 nm, with or without polysaccharide coating), or silver nitrate (AgNO3) at concentrations of 100, 50, 25, and 12.5 μg/mL were evaluated for efficacy using a plaque reduction assay. Both Ag-PS-25
(polysaccharide-coated, 25 nm) and Ag-NP-55 (non-coated, 55 nm) exhibited a significant (P ≤ 0.05) dose-dependent effect of test compound concentration on the mean number of plaque-forming units (PFU). All concentrations
of silver nitrate (except 100 μg/mL) and Ag-PS-10 promoted significant (P ≤ 0.05) decreases in the number of observed PFU compared to untreated controls. Some nanoparticle treatments led to increased
MPV PFU ranging from 1.04- to 1.8-fold above controls. No cytotoxicity (Vero cell monolayer sloughing) was caused by any test
compound, except 100 μg/mL AgNO3. These results demonstrate that silver-based nanoparticles of approximately 10 nm inhibit MPV infection in vitro, supporting
their potential use as an anti-viral therapeutic. 相似文献
15.
Aleksandra Szydłowska-Czerniak György Karlovits Csilla Dianoczki Katalin Recseg Edward Szłyk 《Journal of the American Oil Chemists' Society》2008,85(2):141-149
The oxygen radical absorbance capacity (ORAC) and the ferric reducing antioxidant power (FRAP) methods were used for the determination
of antioxidant capacities (AC) of rapeseed oils at different steps of technological process and olive oils. The mean ORAC
and FRAP results obtained for rapeseed oils (1,106–160 and 552–95.6 μmol TE/100 g) were higher than for olive oils (949–123
and 167–32.1 μmol TE/100 g). Although, FRAP values were lower than ORAC values for all studied oils, there is a linear and
significant correlation between these two analytical methods (r = 0.9665 and 0.9298, P < 0.0005) for rapeseed and olive oils, respectively). Also, total phenolic compounds in rapeseed oils and olives correlated
with antioxidant capacities (correlation coefficient ranged between 0.9470 and 0.8049). The refining process of rapeseed oils
decreased the total phenolics content and antioxidant capacities by about 80%. 相似文献
16.
John W. Parry Zhihong Cheng Jeffrey Moore Liangli Lucy Yu 《Journal of the American Oil Chemists' Society》2008,85(5):457-464
Cold-pressed seed flours from pumpkin, parsley, mullein, cardamom, and milk thistle were examined for total oil, fatty acid
profile of the oil, total phenolic content (TPC), scavenging activities against peroxyl (ORAC), hydroxyl (HOSC) and 2,2-diphenyl-1-picrylhydrazyl
(DPPH) (RDSC) radicals, and antiproliferative capacity against HT-29 human colon cancer cells. The cold-pressed parsley seed
flour contained a very high concentration of total oil—17.6 g/100 g flour—with primarily C18:1 fatty acid at 86.2 g/100 g
fatty acids. All other flour oils had relatively high levels of saturated fats, ranging from 39.0 to 62.9 g/100 g fatty acids.
The tested seed flours demonstrated significant TPC and free radical scavenging activities. Milk thistle seed flour had the
highest TPC value of 25.2 mg gallic acid equivalent per g flour (GAE mg/g) followed by that of parsley seed flour at 8.1 GAE
mg/g. Milk thistle seed-flour extract also had significantly higher antioxidant activities than all other extracts against
all tested radicals. The milk thistle seed-flour extract had an ORAC value of 1131 μmol trolox equivalents (TE) per g flour
(TE μmol/g), a HOSC value of 893 TE μmol/g, and an RDSC value of 61 TE μmol/g. Also, ORAC, HOSC, and TPC values were significantly
correlated (P < 0.01) under the experimental conditions. The cold-pressed milk thistle seed flour inhibited the proliferation of HT-29
cancer cells in a dose-dependent manner. Results from this study suggest that these cold-pressed seed flours may serve as
natural sources of antioxidants and may be used to improve human health. 相似文献
17.
The goal of this study was to determine the mechanisms of n-3 polyunsaturated fatty acids (n-3 PUFA) on anti-arrhythmias and
prevention of sudden death. The calcium-tolerant Sprague–Dawley rat ventricular myocytes were isolated by enzyme digestion.
Effects of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on action potentials and transient outward potassium
currents (I
to) of epicardial ventricular myocytes were investigated using whole-cell patch clamp techniques. Action potential durations
(APDs) and I
to were observed in different concentrations of DHA and EPA. APD25, APD50, and APD90 with 0.1 μmol/L DHA and EPA were prolonged less than 15% and 10%. However, APDs were prolonged in concentration-dependent
manners when DHA and EPA were more than 1 μmol/L. APD25, APD50, and APD90 were 7.7 ± 2.0, 21.2 ± 3.5, and 100.1 ± 9.8 ms respectively with 10 μmol/L DHA, and 7.2 ± 2.5, 12.8 ± 4.2, and 70.5 ± 10.7 ms
respectively with 10 μmol/L EPA. I
to currents were gradually reduced with the increased concentrations of DHA and EPA from 1 to 100 μmol/L, and their half-inhibited
concentrations were 2.3 ± 0.2 and 3.8 ± 0.6 μmol/L. The results showed APDs were prolonged and I
to current densities were gradually reduced with the increased concentrations of DHA and EPA. The anti-arrhythmia mechanisms
of n-3 PUFA are complex, however, the effects of n-3 PUFA on action potentials and I
to may be one of the important mechanisms. 相似文献
18.
Betula pubescens bud flavonoid aglycones reportedly have negative effects on the performance of first instar Epirrita autumnata and, thus, may defend birch leaves from larval defoliation. We hypothesized that the detrimental effects of these lipophilic flavonoids on larvae are due to their high levels in birch buds and/or the inability of naïve neonates to glycosylate them, which we have shown to occur in fifth instars. To test the latter hypothesis, we investigated the biochemical transformation of bud flavonoids in first instar E. autumnata. We found that newly hatched larvae have the ability to glycosylate birch bud/leaf flavonoid aglycones into corresponding glycosides. Moreover, we suggest that glycosylation may depend upon the chemical character of the aglycone and is an important factor in the performance of first instars. 相似文献
19.
YB Wu LJ Zheng JG Wu TQ Chen J Yi JZ Wu 《International journal of molecular sciences》2012,13(6):7163-7173
The antioxidant activities of ethanolic crude extract (ECE) and its four different solvent sub-fractions (namely, petroleum ether fraction (PEF), ethyl acetate fraction (EAF), n-butanol fraction (BF) and the aqueous fraction (AF) from the receptacles of Nelumbo nucifera Gaertn. (Receptaculum Nelumbinis) were investigated using two in vitro antioxidant assays. BF showed the highest total phenolic content (607.6 mg/g gallic acid equivalents), total flavonoid content (862.7 mg/g rutin equivalents) and total proanthocyanidin content (331.0 mg/g catechin equivalents), accompanied with the highest antioxidant activity compared to other fractions through 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging assays. Five flavonol glycosides, namely hyperoside (1), isoquercitrin (2), quercetin-3-O-β-d-glucuronide (3), isorhamnetin-3-O-β-d-galactoside (4) and syringetin-3-O-β-d-glucoside (5) were isolated from the Receptaculum Nelumbinis. Compounds 2-5 were isolated for the first time from the Receptaculum Nelumbinis. The five isolated flavone glycosides, particularly compounds 1-3, demonstrated significant DPPH and ABTS radical scavenging activity, with IC(50) values of 8.9 ± 0.2, 5.2 ± 0.2, 7.5 ± 0.1 for DPPH and 114.2 ± 1.7, 112.8 ± 0.8, 172.5 ± 0.7 μg/mL for ABTS, respectively. These results suggest that Receptaculum Nelumbinis has strong antioxidant potential and may be potentially used as a safe and inexpensive bioactive source of natural antioxidants. 相似文献
20.
Guowei Wang Feng Zhang Huaping Zuo Zhenhua Yu Shihui Ge 《Nanoscale research letters》2010,5(7):1107-1110
A series of nano-granular films composed of magnetic metal (Fe65Co35) granules with a few nanometers in size and semiconductor oxide (ZnO) have been fabricated by a magnetron sputtering method,
and excellent soft magnetic properties have been achieved in a wide metal volume fraction (x) range for as-deposited samples due to the exchange coupling between FeCo granules (a ferromagnetic interaction in nano-scale).
In a wide range (0.53 < x < 0.71), the films exhibit coercivity H
C
not exceeding 15 Oe, along with high resistivity. Especially for the sample with x = 0.67, coercivities in hard and easy axes are 1.43 and 7.08 Oe, respectively, 4πM
S
= 9.85 kg, and ρ reaches 2.06 × 103 μΩ cm. The dependence of complex permeability μ = μ′ − jμ″ on frequency shows that the real part μ′ is more than 100 below 1.83 GHz and that the ferromagnetic resonance frequency reaches 2.31 GHz, implying the promising for
high frequency application. The measured negative temperature coefficient of resistivity reveals that may be the weak localized
electrons existing in samples mediate the exchange coupling. 相似文献