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1.
Single-stranded DNA (ssDNA)-binding protein (SSB) plays a crucial role in DNA replication, repair, and recombination as well as replication fork restarts. SSB is essential for cell survival and, thus, is an attractive target for potential antipathogen chemotherapy. Whether naturally occurring products can inhibit SSB remains unknown. In this study, the effect of the flavonols myricetin, quercetin, kaempferol, and galangin on the inhibition of Pseudomonas aeruginosa SSB (PaSSB) was investigated. Furthermore, SSB was identified as a novel quercetin-binding protein. Through an electrophoretic mobility shift analysis, myricetin could inhibit the ssDNA binding activity of PaSSB with an IC50 of 2.8 ± 0.4 μM. The effect of quercetin, kaempferol, and galangin was insignificant. To elucidate the flavonol inhibition specificity, the crystal structure of PaSSB complexed with the non-inhibitor quercetin was solved using the molecular replacement method at a resolution of 2.3 Å (PDB entry 7VUM) and compared with a structure with the inhibitor myricetin (PDB entry 5YUN). Although myricetin and quercetin bound PaSSB at a similar site, their binding poses were different. Compared with myricetin, the aromatic ring of quercetin shifted by a distance of 4.9 Å and an angle of 31° for hydrogen bonding to the side chain of Asn108 in PaSSB. In addition, myricetin occupied and interacted with the ssDNA binding sites Lys7 and Glu80 in PaSSB whereas quercetin did not. This result might explain why myricetin could, but quercetin could not, strongly inhibit PaSSB. This molecular evidence reveals the flavonol inhibition specificity and also extends the interactomes of the natural anticancer products myricetin and quercetin to include the OB-fold protein SSB. 相似文献
2.
Carbon dioxide has been previously identified as a critical volatile factor that stimulates hyphal growth ofGigaspora margarita, a vesiculararbuscular mycorrhizal fungus, and we determined the optimal concentration at 2.0%. The beneficial effect of CO2 on fungal development is also visible in the presence of stimulatory (quercetin, myricetin) or inhibitory (naringenin) flavonoids. Sterile root exudates from carrot seedlings stimulate the hyphal development ofG. margarita in the presence of optimal CO2 enrichment. Three flavonols (quercetin, kaempferol, rutin or quercetin 3-rutinoside) and two flavones (apigenin, luteolin) were identified in carrot root exudates by means of HPLC retention time. Flavonols like quercetin and kaempferol are known to have stimulatory effects on hyphal growth ofG. margarita. 相似文献
3.
Cannac M Ferrat L Barboni T Pergent G Pasqualini V 《Journal of chemical ecology》2007,33(5):1083-1088
In recent times, more and more studies have focused on flavonoids as biomarkers of environmental quality in aquatic plants,
in particular, Posidonia oceanica (Linnaeus) Delile. It is therefore of interest to determine how different prehandling methods can affect flavonoid concentrations.
The methods tested were (1) immediate extraction of fresh samples, (2) extraction after 48 hr chilling, (3) freeze-drying,
and (4) oven drying. Chilling and freeze-drying considerably altered the quantity of flavonoids measured, but not their profile.
The effect of oven drying was not significant. Chilling led to a loss of 57% of total (pro)anthocyanidins, 39% of total flavonols,
and 48% of all simple flavonols (myricetin, quercetin, isorhamnetin, and kaempferol). Freeze-drying caused a loss of 71% of
total (pro)anthocyanidins, 87% of total flavonols, and 95% of all simple flavonols. 相似文献
4.
The antioxidant activities of the flavonol aglycones, quercetin and myricetin, and their selected glycosides were compared
in bulk methyl linoleate oxidized at 40°C. Methyl linoleate hydroperoxide formation, hydroperoxide isomer distribution, and
ketodiene formation were followed by using high-performance liquid chromatography (HPLC) analysis. The aglycones, quercetin
and myricetin, were consistently more active in bulk methyl linoleate than their glycosides and more active than α-tocopherol
at 500 and 1000 μM. At 50 μM, the order of activity was myricetin > α-tocopherol > quercetin, and the order of activity of
quercetin and its derivatives was quercetin > quercitrin > isoquercitrin > rutin. Myricitrin was slightly less active than
myricetin. The sugar moiety was shown to have a marked effect on the antioxidant activity of flavonols. The rhamnoside derivatives,
quercitrin and myricitrin, both possessed activity close to that of their corresponding aglycones. The different activities
of glycosides could be partly explained by different solubilities and by differences in oxidizability of glycosides containing
a monosaccharide or disaccharide at the C3 position. The effect on hydroperoxide isomer distribution indicates that α-tocopherol was a more effective hydrogen donor
than flavonoids, although flavonoids were more effective in inhibiting oxidation of methyl linoleate. 相似文献
5.
《分离科学与技术》2012,47(3):518-524
High-performance liquid chromatography coupled to an on-line ABTS+-based assay (on-line HPLC-ABTS+) system was used to determine the principle antioxidants in azalea flowers. Three flavonoids, myricetin, quercetin, and kaempferol, recovered in ethyl acetate extracts of azalea flowers were determined to have antioxidant activities. These three flavonoids were isolated and purified by successive centrifugal partition chromatography (CPC) using two different biphasic solvent systems, consisting of n-hexane-ethyl acetate-methanol-water (3:5:3:5 or 4:5:4:5, v/v). A total of 46.2 mg of myricetin, 28.9 mg of quercetin, and 10.6 mg of kaempferol with purities of 97.0%, 95.4%, and 93.9%, respectively, were purified from 500 mg of ethyl acetate soluble material from azalea flowers. The structures were identified by their retention time, UV spectra, and ESI-MS in the positive ion mode and were confirmed by NMR experiments. 相似文献
6.
M. Gabriela Gallego Michael H. Gordon Francisco J. Segovia Monika Skowyra María P. Almajano 《Journal of the American Oil Chemists' Society》2013,90(10):1559-1568
Lipid oxidation is the major form of deterioration in foods because it decreases food quality and nutritional value, and may have negative health implications. Selected aromatic plant extracts from leaves, flowers and stems of rosemary, thyme and lavender were investigated for their antioxidant activity. The total polyphenol content was determined by the Folin–Ciocalteu assay and the antioxidant capacity was determined by the Trolox equivalent antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl, oxygen radical absorbance capacity and ferric-reducing antioxidant power assays. For all four antioxidant assays, the extracts from thyme flowers, lavender leaves and thyme leaves had the highest antioxidant activity, followed by rosemary stems, rosemary leaves, and lavender stems, and the lavender flowers and thyme stems had the lowest antioxidant activity. The antioxidant activity was correlated with the polyphenol content, although minor deviations were observed. In oil-in-water emulsion, extracts from rosemary leaves and thyme leaves were most effective at retarding oxidation followed by the rosemary stems and thyme flowers. Extracts from thyme flowers and lavender leaves were less effective in the emulsion than predicted by the homogeneous antioxidant assays. This study demonstrated the potential use of plants extract as substitutes for synthetic antioxidants. 相似文献
7.
Effects of flavonoids on thermal autoxidation of palm oil: Structure-activity relationships 总被引:7,自引:3,他引:4
The effects of several flavonoids and other known antioxidants on the thermal autoxidation of refined, bleached and deodorized
(RBD)-palm oil were studied. The lipid peroxidation was indexed by measuring the malonyldialdehyde (MDA) production using
the 2-thiobarbituric acid (TBA) test. The antioxidative action decreased in the order of morin > kaempferol > myricetin >
quercetin > vitamin A > α-tocopherol > apigenin > (+)-catechin > chrysin > datiscetin > luteolin > naringin > taxifolin >
rutin > butylated hydroxytoluene (BHT) > naringenin.
The flavonoid aglycones were more potent in their antiperoxidative action than their corresponding glycosides. Structure-activity
revealed that the flavonoid molecule with polyhydroxylated substitutions on rings A and B, a 2–3 double bond, a free 3-hydroxyl
substitution and a 4-keto moiety, would confer potent antiperoxidative properties upon the compound. The flavonols, namely
morin, myricetin, kaempferol and quercetin, would be suitable potential antioxidants for use in the stabilization of RBD-palm
oil and its fractions against thermal autoxidation. The structural activity of the flavonoids on the RBD-palm oil was similar
to those observed for these compounds in animal tissue or enzyme systems. 相似文献
8.
Chia seeds as a source of natural lipid antioxidants 总被引:8,自引:0,他引:8
M. Silvia Taga E. E. Miller D. E. Pratt 《Journal of the American Oil Chemists' Society》1984,61(5):928-931
Chia (Salvia sp) seeds were investigated as a source of natural lipid antioxidants. Methanolic and aqueous extracts of defatted chia seeds
possessed potent antioxidant activity. Analysis of 2 batches of chia-seed oils demonstrated marked difference in the fatty
acid composition of the oils. In both batches, the oils had high concentrations of polyunsaturated fatty acids. The major
antioxidant activity in the nonhydrolyzed extract was caused by flavonol glycosides, chlorogenic acid (7.1 × 10−4 mol/kg of seed) and caffeic acid (6.6 × 10−3 m/kg). Major antioxidants of the hydrolyzed extracts were flavonol aglycones/kaempferol (1.1 × 10−3 m/kg), quercetin (2.0 × 10−4 m/kg) and myricetin (3.1 × 10−3 m/kg); and caffeic acid (1.35 × 10−2 m/kg). Two methods were used to measure antioxidant activities. Both were based on measuring bleaching ofβ-carotene in the coupled oxidation ofβ-carotene and linoleic acid in the presence of added antioxidants. 相似文献
9.
Masashi Mizuno Asuka Fujioka Shiho Bitani Ken-ichiro Minato Hiroyuki Sakakibara 《International journal of molecular sciences》2022,23(20)
In recent years, the incidence of type I hypersensitivity including hay fever has been increasing year by year in Japan. Our previous study using mice showed that only oral, but not intraperitoneal, administration of fucoidan extracted from seaweed (Saccharina japonica) suppressed type I hypersensitivity by secretion of galectin-9, which has a high affinity for IgE in the blood. However, the amount of seaweed required to achieve this activity is quite high (12 g dry weight per person per day). Therefore, the purpose of this study was to search for food ingredients in vegetables that enhance type I hypersensitivity suppression effect when consumed together with fucoidan. As a result, the enhanced effect was observed in extracts from Welsh onions and onions among vegetables. When we compared the polyphenols in the vegetables that showed activity with those that did not, flavonols such as quercetin and kaempferol were found as candidates. When quercetin or kaempferol (100 μg each) were orally administered at the same time, even at amounts where fucoidan alone showed no anti-allergic activity, anti-allergic effects were observed. More interestingly, when both flavonols were combined and administered simultaneously at half the amount of each of the above flavonols (50 μg), while the fucoidan amount remained the same, a similar effect was observed as when each flavonol (100 μg) was administered alone. The simultaneous intake of fucoidan and vegetables containing high contents of quercetin or kaempferol may reduce fucoidan intake while maintaining the allergy suppression effect, suggesting the importance of food combination. 相似文献
10.
Andrea Roedig-Penman Michael H. Gordon 《Journal of the American Oil Chemists' Society》1998,75(2):169-180
The effect of quercetin and myricetin on the stability of sunflower oil and oil-in-water emulsions was studied by storage
experiments monitored by measurement of peroxide values, conjugated dienes, and headspace volatile analysis. Myricetin showed
strong antioxidant activity in oils stored at 60 or 30°C and in oil-in-water emulsions stored at 30°C, whether tocopherols
or citric acid were present or not; however, quercetin showed similar antioxidant activity in stripped sunflower oil but no
activity in oils that contained tocopherols and citric acid. This showed that myricetin is effective owing to strong radical
scavenging and metal-chelating properties, whereas quercetin has weaker radical scavenging activity, although it is also active
by metal-chelation. The effects of copper and iron salts on the antioxidant activity of myricetin and quercetin were studied
in sunflower oil and oil-in-water emulsions. Quercetin and myricetin enhanced the prooxidant effect of cupric chloride in
oil-in-water emulsions (pH 7.4), but this effect was not observed with cupric stearate. The addition of myricetin to emulsions
that contained ferric chloride at pH 5.4 also produced a strong prooxidant effect, and small prooxidant effects of flavonols
were also detected in the presence of cupric chloride under these conditions. However, myricetin and quercetin reduced the
prooxidant effect of ferric palmitate in oils. Myricetin also showed a strong antioxidant effect in oil that contained cupric
stearate, although quercetin had no significant effect on the oxidative stability of this system. It therefore appears that
flavonols may exert a prooxidant effect in the presence of metal salts, but the nature of the metal salt is important in determining
whether a prooxidant effect occurs. 相似文献
11.
Lipoxygenase-oxidized soap stock as source of hydroxy conjugated octadecadienoic acids 总被引:1,自引:0,他引:1
A laboratory procedure was developed for the production of hydroxy conjugated octadecadienoic acids (HOCD). Lipoxygenase oxidation
of distilled or crude soap stock produces hydroperoxy conjugated octadecadienoic acids, which can be reduced to HOCD. Crude
aqueous soy flour extracts and defatted soy flour are convenient, effective and inexpensive lipoxygenase sources. This new
procedure allows high substrate concentrations of 100 mg/ml to be used while achieving 75% to 90% oxidation of the available
linoleic acid during a reaction time of 20 to 40 min. Aqueous ethanol and dimethyl sulfoxide (DMSO) solvent systems were compared.
The DMSO system produced higher yields of hydroperoxy acids with low enzyme concentrations. Hydroperoxide yields are good
when short reaction times, high pH levels and free radical scavengers are used.
Presented at the AOCS Meeting, Chicago, September 1970.
No. Utiliz. Res. Dev. Div., ARS, USDA. 相似文献
12.
Antioxidant activity of grape extracts in a lecithin liposome system 总被引:15,自引:0,他引:15
Ock-Sook Yi Anne S. Meyer Edwin N. Frankel 《Journal of the American Oil Chemists' Society》1997,74(10):1301-1307
Extracts of 14 different grapes were tested for their antioxidant activities in a copper-catalyzed lecithin liposome oxidation
assay and analyzed for their phenolic components by high-performance liquid chromatography (HPLC). The total phenolic contents
of the grape extracts varied from 176 to 1236 mg gallic acid equivalents (GAE)/L. Extracts of red wine grape varieties contained
higher concentrations of phenolics than other varieties. When compared at the same 20 μM GAE basis, the grape extracts inhibited
formation of conjugated diene hydroperoxides by 25.1 to 67.9%, and hexanal formation by 49.3 to 97.8%. Extracts of red table
grape varieties Red Globe and Emperor and white wine grape varieties Chardonnay and Sauvignon Blanc gave the highest antioxidant
activities. The relative percentage inhibition of conjugated dienes and hexanal correlated with total phenols (r=0.86 and 0.89). HPLC analyses showed that anthocyanins were the most abundant phenolic compounds in extracts of red grapes,
and flavonols were most abundant in extracts of white grapes. 相似文献
13.
Z. Y. Chen P. T. Chan H. M. Ma K. P. Fung J. Wang 《Journal of the American Oil Chemists' Society》1996,73(3):375-380
There is an increasing interest in the biological effects of natural antioxidants present in teas on formation ofin vivo free radicals, carcinogenesis, and atherogenesis. Teas are traditionally classified into six major groups, namely, green,
yellow, white, black, dark-green, and oolong teas. The present study examined the antioxidative activity of ethanol extracts
from these six major groups of teas against oxidation of heated canola oil. The oxidation was conducted at 100°C by monitoring
oxygen consumption and changes in linoleic and linolenic acids in canola oil. The ethanol extracts of green, yellow, and white
teas strongly inhibited oxidation of canola oil compared to butylated hydroxytoluene, probably due to the presence of natural
polyphenols. In contrast, oolong teas examined exhibited only moderate antioxidative activity because of the partial destruction
of natural polyphenols by semifermentation. The ethanol extracts of black, dark-green, and ginseng teas studied showed little
or no protection to canola oil from lipid oxidation, probably due to the complete destruction of natural polyphenols by fermentation
during manufacturing processes. 相似文献
14.
Louis-Jér?me Leba Christel Brunschwig Mona Saout Karine Martial Emmanuelle Vulcain Didier Bereau Jean-Charles Robinson 《International journal of molecular sciences》2014,15(10):18023-18039
This study was aimed at assessing the DNA damage protective activity of different types of extracts (aqueous, methanolic and acetonic) using an in vitro DNA nicking assay. Several parameters were optimized using the pUC18 plasmid, especially FeSO4, EDTA, solvent concentrations and incubation time. Special attention has been paid to removing the protective and damaging effect of the solvent and FeSO4 respectively, as well as to identifying the relevant positive and negative controls. For each solvent, the optimal conditions were determined: (i) for aqueous extracts, 0.33 mM of FeSO4 and 0.62 mM of EDTA were incubated for 20 min at 37 °C; (ii) for acetone extracts, 1.16% solvent were incubated for 15 min at 37 °C with 1.3 mM of FeSO4 and 2.5 mM of EDTA and (iii) for methanol extracts, 0.16% solvent, were incubated for 1.5 h at 37 °C with 0.33 mM of FeSO4 and 0.62 mM of EDTA. Using the optimized conditions, the DNA damage protective activity of aqueous, methanolic and acetonic extracts of an Amazonian palm berry (Oenocarpus bataua) and green tea (Camellia sinensis) was assessed. Aqueous and acetonic Oenocarpus bataua extracts were protective against DNA damage, whereas aqueous, methanolic and acetonic extracts of Camellia sinensis extracts induced DNA damage. 相似文献
15.
In this study, we investigated how the extent of ripeness affects the yield of extract, total phenolics, total flavonoids, individual flavonols and phenolic acids in strawberry and mulberry cultivars from Pakistan. In strawberry, the yield of extract (%), total phenolics (TPC) and total flavonoids (TFC) ranged from 8.5-53.3%, 491-1884 mg gallic acid equivalents (GAE)/100 g DW and 83-327 mg catechin equivalents (CE)/100 g DW, respectively. For the different species of mulberry the yield of extract (%), total phenolics and total flavonoids of 6.9-54.0%, 201-2287 mg GAE/100 g DW and 110-1021 mg CE/100 g DW, respectively, varied significantly as fruit maturity progressed. The amounts of individual flavonols and phenolic acid in selected berry fruits were analyzed by RP-HPLC. Among the flavonols, the content of myricetin was found to be high in Morus alba (88 mg/100 g DW), the amount of quercetin as high in Morus laevigata (145 mg/100 g DW) while kaempferol was highest in the Korona strawberry (98 mg/100 g DW) at fully ripened stage. Of the six phenolic acids detected, p-hydroxybenzoic and p-coumaric acid were the major compounds in the strawberry. M. laevigata and M. nigra contained p-coumaric acid and vanillic acid while M. macroura and M. alba contained p-hydroxy-benzoic acid and chlorogenic acid as the major phenolic acids. Overall, a trend to an increase in the percentage of extraction yield, TPC, TFC, flavonols and phenolic acids was observed as maturity progressed from un-ripened to fully-ripened stages. 相似文献
16.
Tarling CA Woods K Zhang R Brastianos HC Brayer GD Andersen RJ Withers SG 《Chembiochem : a European journal of chemical biology》2008,9(3):433-438
Specific inhibitors of human pancreatic alpha-amylase (HPA) have potential as oral agents for the control of blood glucose levels in the treatment of diabetes and obesity. In a search for novel inhibitors, a library of 30 000 crude biological extracts of terrestrial and marine origin has been screened. A number of inhibitory extracts were identified, of which the most potent was subjected to bioassay-guided purification. A family of three glycosylated acyl flavonols, montbretins A-C, was thereby identified and characterized as competitive amylase inhibitors, with K(i) values ranging from 8.1-6100 nM. Competitive inhibition by myricetin, which corresponds to the flavone core, and noncompetitive inhibition by a second fragment, ethyl caffeiate, suggest a binding mode for these inhibitors. 相似文献
17.
Hiroaki Kubouchi Hideto Kai Kazuo Miyashita Koji Matsuda 《Journal of the American Oil Chemists' Society》2002,79(6):567-570
The effects of two types of commercial emulsifiers, sucrose FA esters and polyglycerol FA esters, on the oxidation of soybean
oil TAG-in-water emulsions were studied. Both emulsifiers influenced the oxidative stability of soybean oil TAG in the emulsion,
but they had little effect on the oxidation of TAG in bulk phase. When the TAG were dispersed with sucrose esters having the
same FA composition, the oxidative stability increased as their hydrophilic-lipophilic balance (HLB) increased. On the other
hand, when the HLB was the same, the oxidative stability increased with increasing acyl chain length of the FA esterified
on sucrose ester. However, the effect of the polyglycerol ester could not be explained by the relationship with HLB or the
acyl composition. When the stability of TAG in emulsion was compared under the same concentrations of TAG, emulsifier, and
oxidation inducer, the TAG dispersed with sucrose esters were oxidatively less stable than with polyglycerol esters. Analysis
of the emulsion droplet size suggested that the lower oxidative stability of TAG dispersed with sucrose esters was partly
due to their relatively smaller droplet sizes. 相似文献
18.
Antioxidant Phenolics of Millet Control Lipid Peroxidation in Human LDL Cholesterol and Food Systems
Anoma Chandrasekara Fereidoon Shahidi 《Journal of the American Oil Chemists' Society》2012,89(2):275-285
Phenolic extracts from seven millet varieties, namely kodo, finger (Ravi), finger (local), proso, foxtail, little and pearl
were evaluated for their inhibitory effects on lipid peroxidation in in-vitro copper-mediated human LDL cholesterol oxidation
and several food model systems, namely cooked comminuted pork, stripped corn oil, and linoleic acid emulsion. The total phenolic
content (TPC) and free radical scavenging activities were measured. The TPC ranged from 146 to 1156 μmol ferulic acid equiv
(FAE)/g crude extract and the corresponding values based on defatted weight of grain ranged from 8.6 to 32.4 μmol FAE/g. At
a final concentration of 0.05 mg/mL, millet extracts inhibited LDL cholesterol oxidation by 1–41%. All seven varieties exhibited
effective inhibition of lipid oxidation in food systems used in this study and kodo millet exhibited superior inhibition of
lipid peroxidation, similar to butylated hydroxyanisole at 200 ppm. Thus, millets may serve as a natural source of antioxidants
in food applications and as a nutraceutical and functional food ingredient in health promotion and disease risk reduction. 相似文献
19.
Pin-Der Duh Wen Jye Yen Pin-Chan Du Gow-Chin Yen 《Journal of the American Oil Chemists' Society》1997,74(9):1059-1063
The antioxidant activity of methanolic extracts of mung bean hulls was investigated. Extracts at a concentration of 100 ppm exhibited stronger antioxidant activity than 100 ppm dl-α-tocopherol (Toc) or 100 ppm butylated hydroxyanisole on the peroxidation of linoleic acid. Moreover, a synergistic effect was observed when 100 ppm of the extract was mixed with 100 ppm Toc. Also, the extracts showed good inhibitory activity in soybean oil oxidation, which was examined by peroxide value, thiobarbituric acid, and gas chromatography of oxidized fatty acid methyl esters. The extracts can reduce the formation of both primary and secondary oxidation products of soybean oil. The extracts had reducing power and scavenged 1,1-diphenyl-2-picrylhydrazyl radical, which may in part be responsible for their antioxidant activity. Based on the results obtained, mung bean hulls are a potential source of natural antioxidants owing to their marked antioxidant activity. 相似文献
20.
以槲皮素、山奈素和异鼠李素为指标,建立HPLC法测定牙膏中银杏叶提取物总黄酮苷的含量。采用Agilent ZORBAX Eclipse XDB-C18色谱柱(Analytical 4.6×250mm 5-Micron);流动相为甲醇-0.4%磷酸(55/45,V/V);流速为1.0mL/min;检测波长为360nm;柱温为40℃;进样量为20μL。结果表明,槲皮素、山奈素和异鼠李素浓度分别在2.1~21.0、1.8~18.0和0.42~4.2μg/mL范围内呈良好的线性关系,相关系数分别为:0.9999、0.9999和0.9998;槲皮素、山奈素和异鼠李素回收率分别为:97.7%、98.3%和97.6%。该方法简单、灵敏、准确,可用于牙膏中银杏叶提取物总黄酮苷含量的测定。 相似文献