首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 62 毫秒
1.
Antioxidant compounds from the leaves of Peucedanum japonicum thunb   总被引：1，自引：0，他引：1  
Seventeen compounds were isolated from the n-butanol soluble fraction of the leaves of Peucedanum japonicum Thunb. On the basis of MS and various NMR spectroscopic techniques, the structures of the isolated compounds were determined as isoquercitrin (1), rutin (2), 3-O-caffeoylquinic acid (3), 4-O-caffeoylquinic acid (4), 5-O-caffeoylquinic acid (5), cnidioside A (6), praeroside II (7), praeroside III (8), apterin (9), esculin (10), (R)-peucedanol (11), (R)-peucedanol 7-O-beta-d-glucopyranoside (12), l-tryptophan (13), uracil (14), guanosine (15), uridine (16), and thymidine (17). All compounds except 11 and 12 were isolated for the first time from P. japonicum. Several isolated compounds were quantified by high-performance liquid chromatography analysis. In addition, all isolated compounds were examined for radical scavenging on 1,1-diphenyl-2-picrylhydrazyl radical and for inhibition of oxidation of liposome induced by 2,2'-azobis(2-amidinopropane)dihydrochloride. Compounds 2-5 were found to be the major potent constituents, which contribute to the antioxidant activity of P. japonicum leaves.  相似文献   

2.
DNA has been isolated from the bacterial fraction of two soils. Numbers of bacteria, determined by fluorescence microscopy were 1.1 and 2.2·1010 cells g?1 dry wt. The total amounts of bacterial DNA in these soils were 90 and 187 μg g?1 dry wt respectively.A modification of Marmur's method was used to isolate DNA, but difficulties in separating DNA from humic substances gave low yields and impure DNA.DNA could be partly separated from humic material in the presence of 8 m urea by ion-exchange chromatography on DEAE-Sepharose CL-6B. Final purification was obtained by chromatography on a hydroxyapatite column. When lowering the EDTA concentration in the saline-EDTA solution used for lysis, the amount of humic substances in the cell-free lysate after centrifugation was considerably decreased. The lysate could then be chromatographed directly on hydroxyapatite. Quantities up to 1.5 mg DNA high purity was isolated from 90 g wet soil (37 g dry wt).The isolated DNA was characterized by treatment with DNAse and absorption spectra. No uncommon bases were revealed by thin layer chromatography of the DNA hydrolysates. Melting curves of the isolated DNA showed a relatively broad melting profile, with half maximum hyperchromicity (Tm) near 90°C. Sedimentation coefficients determined by analytical ultracentrifugation showed that the isolated DNA had a high molecular weight, ranging from 2.3 to 10.1·105 daltons.  相似文献   

3.
A bioassay-guided fractionation of water extracts from Helianthus annuus cv. SH-222 was carried out. Ten lignans and a phenylpropanoid were isolated from the polar bioactive fractions of H. annuus. This study is the first to report lignans as constituents of sunflower and is the first time that tanegool has been isolated as a natural aglycone. Additionally, we report biological activities of the isolated compounds. The general bioactivity has been evaluated using the wheat coleoptiles bioassay. The phytotoxic activities of compounds pinoresinol, lariciresinol, dihydro-dehydrodiconiferilic alcohol, and l-(4'-hydroxy-3'-methoxyphenyl)-2-[4' '-(3hydroxypropyl)-2' '-methoxyphenoxy]propane-l,3-diol were also evaluated in a bioassay on the standard target species. The structure-activity relationships are discussed.  相似文献   

4.
Twenty-five compounds were identified from the dichloromethane and methanol extracts of royal jelly from Greece. Among them, 16 compounds are reported for the first time as royal jelly constituents, whereas 7 of them are isolated for the first time as natural products. The 7 new compounds were fatty acid derivatives: 10-acetoxydecanoic acid (1), trans-10-acetoxydec-2-enoic acid (2), 11-oxododecanoic acid (3), (11S)-hydroxydodecanoic acid (4), (10R,11R)-dihydroxydodecanoic acid (5), 3,11-dihydroxydodecanoic acid (6), and (11S),12-dihydroxydodecanoic acid (7). The structures of the isolated compounds were determined by spectroscopic methods, mainly by the concerted application of 1D and 2D NMR techniques (HMQC, HMBC) and mass spectrometry. The studied sample and the isolated compounds were tested for their antimicrobial activity against Gram-positive and Gram-negative bacteria and fungi and exhibited interesting activities.  相似文献   

5.
葵花粕中分离蛋白的成分及特性   总被引：8，自引：0，他引：8  
该文以水酶法提取葵花籽油后的葵花粕为原料，通过盐提酸沉法提取其中的分离蛋白，并对其进行组分分析、氨基酸成分分析、电泳图谱分析和凝胶色谱分析，同时对其溶解性、吸水性、吸油性、乳化性和起泡性等功能特性进行研究。结果显示葵花籽分离蛋白的氨基酸组成与FAO必须氨基酸需要量模式相比赖氨酸含量较低，功能特性好于或接近大豆分离蛋白。葵花分离蛋白含有3个主要组分，其分子量分别为380×103，100×103和27×103，绿原酸与分离蛋白紧密结合。  相似文献   

6.
An extensive phytochemical analysis of the saponin content has been undertaken on leek, Allium porrum L., sown and collected at different seasons. As a result of this investigation, eight saponins (1-8) have been isolated, four of them (5-8) being novel compounds. Compounds 5 and 6, possessing the same tetrasaccharide moiety of compounds 1 and 3, display very unusual spirostane aglycones, 12-ketoporrigenin and 2,12-diketoporrigenin (named porrigenin C), respectively, recently isolated for the first time as free sapogenin in the same plant. Compounds 7 and 8 are rare cholestane bidesmosides possessing a di- and trisaccharide residues linked to a polyhydroxycholesterol aglycone, respectively. The structures of the isolated compounds have been determined by nondegradative spectroscopic analysis, mainly based on NMR. All the eight saponins isolated from leek were tested for their cytotoxic activity against two different cell lines in vitro, and compounds 1, 2, and 6 resulted particularly active.  相似文献   

7.
Tumor necrosis factor-α (TNF-α)-induced reactive oxygen species (ROS) production in HepG2 was used to screen hepatocyte protective compounds from the flowers of Hemerocallis fulva. Three new polyphenols, n-butyl 4-trans-O-caffeoylquinate (1), kaempferol 3-O-{α-L-rhamnopyranosyl(1→6)[α-L-rhamnopyranosyl(1→2)]}-β-D-galactopyranoside (2), and chrysoeriol 7-O-[β-D-glucuronopyranosyl(1→2)(2-O-trans-feruloyl)-β-D-glucuronopyranoside (3), together with four caffeoylquinic acid derivatives (4-7), eight known flavones (8-15), one naphthalene glycoside, stelladerol (16), one tryptophan derivative (17), adenosine (18), and guanosine (19) were isolated from the bioactive fractions of the aqueous ethanol extract of H. fulva flowers. The structures of isolated compounds were characterized by means of spectroscopic data. Compounds 1-3 were described as first isolated natural products. Among the above-mentioned compounds, the caffeoylquinic acid derivatives are the major components with potent free radical scavenging activity in HepG2 cells and are for the first time isolated from H. fulva flowers. A convenient ultraperformance liquid chromatography (UPLC) method was also developed to simultaneously separate and identify caffeoylquinic acids and flavonoids promptly.  相似文献   

8.
The extract of garlic skins (peels) showed strong antioxidant activity, and some responsible constituents were isolated and identified. Garlic (Allium sativum L.) has been used as an herbal medicine, but there is no report on the health benefits of the skin or peel. In this study, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of garlic skin extract was evaluated. Using chromatographic techniques, the active constituents were isolated and subsequently identified. Analyses by high-performance liquid chromatography coupled with a photodiode array detector (HPLC-PDA) suggested that these compounds were phenylpropanoids, which had a characteristic absorbance at 300-320 nm. Liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance analyses allowed the chemical structures of the isolated constituents to be postulated. The proposed compounds were subsequently synthesized and compared with the constituents in the extract using HPLC-PDA and LC-MS. N-trans-Coumaroyloctopamine, N-trans-feruloyloctopamine, guaiacylglycerol-beta-ferulic acid ether, and guaiacylglycerol-beta-caffeic acid ether were identified as were trans-coumaric acid and trans-ferulic acid. Also, the antioxidant activities of these compounds were determined.  相似文献   

9.
The bacteria capable of degrading pentachlorophenol (PCP) were isolated from soil. In the soil perfused with 40 ppm PCP solution, PCP was decomposed and five chlorine atoms of PCP were liberated as chloride ion after about 3 weeks. Re-addition of PCP after its degradation, accelerated the rate of PCP degradation and de-chlorination. After the addition of PCP to the soil three times, bacteria which grew on PCP agar were counted to be about 2 × 107 per gram dry soil. In the liquid medium inoculated with the perfused soil, PCP degradation and complete de-chlorination were found. In this case, multiplication of bacteria capable of growing on PCP agar was found. The bacteria capable of growing on and degrading PCP in the medium with inorganic salts and 40 ppm PCP as a sole source of carbon were isolated from the agar plates for enumeration of the bacteria. From the morphological and physiological properties of the isolated bacteria, the genus of the bacteria was considered to be Pseudomonas or a closely related one. In the culture medium with PCP and inorganic salts, the bacteria degraded PCP and completely de-chlorinated it. The de-chlorination process corresponded approximately to PCP disappearance. Pathways of PCP metabolism are not yet elucidated.  相似文献   

10.
Although starch makes up from 50 to 70% of sweetpotato (SP) dry matter, its role in cooked texture is unknown. The purpose of this research was to characterize raw starches isolated from SP cultivars and experimental selections (C/S) with a wide range of textural properties when cooked and to investigate the relationship between textural properties of the cooked roots and characteristics of the isolated starches. Shear stress measured by uniaxial compression of cooked SP cylinders served as an objective measure of SP texture. Starches were isolated from C/S representing three SP texture types: moist (Jewel and Beauregard); intermediate (NC10-28 and NC2-26); and dry (NC6-30 and NC8-22). The following parameters of isolated starches were measured: amylose content by colorimetric and differential scanning calorimetric (DSC) methods; swelling power, solubility, gelatinization enthalpy (DeltaH), and pasting properties by Brabender amylograph (BA) and rapid viscoanalyzer (RVA). Pasting temperatures for SP C/S measured by BA and RVA were significantly correlated. Due to high shear degradation in RVA, RVA viscosities of starch suspensions decreased as much as 40% during cooking at 95 degrees C, whereas the BA viscosities changed little at this temperature. There were no statistically significant differences among the C/S for amylose or DeltaH. However, significant C/S differences in swelling power, solubility, and pasting properties were observed. Although differences in some rheological and physical properties were observed for C/S starches, shear stress was statistically correlated only with DSC onset temperature (r = 0.78), indicating that factors other than the properties measured on isolated starches are mainly responsible for the texture of cooked SP C/S.  相似文献   

11.
Rhizobium trifolii were isolated from soils along a transect covering a range of soil pH (3.6–5.6) using two varieties of white clover by either growing seedlings directly in soil or in nutrient solution in tubes inoculated with soil. Rhizobia were present at pH 4.5 but absent at pH 3.9. Neither nodule number nor effectiveness were influenced by the method of isolation and the clover variety on which the strain was isolated. There was no relationship between the pH of the soils and either the number of nodules or the effectiveness of the isolates from those soils. Screening the isolates for tolerance of acidity and Al showed that multiplication was unaffected at pH 5.0 but was slowed for all strains at pH 4.5. Multiplication at pH 5.5 was unaffected by 10 μM Al but was inhibited by 50 μM Al. At pH 4.5 all but 16% of the isolates were inhibited by 10 μM Al; none multiplied with 50 μM Al. The strains which multiplied at pH 4.5 with and without Al were isolated equally from soils in the range pH 4.5–5.6. They were also isolated in almost equal proportions from the two varieties of clover and by the two isolation methods. Overall there was little variation in the effectiveness and acid- and Al-tolerance of isolates from these soils of different pH.  相似文献   

12.
Two novel A-seco limonoids, dumnin and dumsenin, were isolated from the methanolic extract of Croton jatrophoides by bioassay-guided fractionation, and the structures were determined by nuclear magnetic resonance, circular dichroism, and mass spectrometry experiments. These compounds showed potent antifeedant activity (PC(50) 相似文献   

13.
对北方地区大豆根瘤菌的生物学特性进行了较为系统的研究,结果表明,黑、辽地区分离、纯化的17株根瘤菌均具有典型的根瘤菌的个体形态和菌落特征,生理生化指标接近,可与辽豆15共生结瘤,分为快生菌和慢生菌。所有根瘤菌均可不同程度地利用供试的5种碳源。耐酸碱度、耐盐性及温度敏感实验表明,菌株HS3可在pH6.0~9.0生长,菌株HH4可耐受1.5%氯化钠,菌株HH4,HH2可在13℃~39℃生长。  相似文献   

14.
Rhodiola crenulata L. is an important species in genus Rhodiola widely used as a health food to reinforce immunity, improve memory and learning, scavenge active-oxygen species, and relieve altitude sickness. Eleven new lignans and a new benzonitrile compound, crenulatanoside A, were isolated from the roots of R. crenulata L. along with 25 known compounds, including 12 lignans. The structures of these compounds were elucidated by spectroscopic data and chemical evidence. Among them, compounds 1-4 and 5-7 were determined to be optical isomers of two 8-O-4' neolignan glycosides. Compounds 8-11 were aryl tetralin type lignans, and compounds 12 and 13 were dihydrobenzofuran neolignans. All of the isolated compounds were evaluated for their inhibitory activity against α-glucosidase. From the data obtained, compound 37 showed strong inhibitory activity against α-glucosidase with an IC(50) value of 96.8 μM.  相似文献   

15.
铅污染是当前土壤重金属污染亟待解决的难题之一，利用微生物与树木的互作来修复铅污染土壤是一个行之有效的方法。为了给利用植物内生细菌提升植物修复铅污染土壤效率提供支持，以毛竹的芽和叶为材料，分离耐铅内生细菌，采用生理分析和分子鉴定相结合的方法，对分离到的菌种进行鉴定。结果发现，在不同铅离子浓度的胁迫下，从毛竹芽和叶组织中分离出27株内生细菌，革兰氏染色和VP实验均为阳性。过氧化氢酶实验中，24株表现为阳性(+)，3株为阴性(-)；甲基红实验测定结果为阳性(++)4株、弱阳性(+)20株、阴性(-)3株。对细菌提取DNA，并PCR扩增16S rDNA序列，通过BLAST比对分析，并用MEGA软件建立发育树等分子鉴定手段，初步推断分离得到的内生细菌为假单胞菌属、蜡样芽孢杆菌和不动杆菌属。  相似文献   

16.
本研究从秤锤树叶片中分离内生菌进行分子鉴定,并接种到无菌组培苗中研究其对植株生长的影响。研究结果显示,从秤锤树叶片中共分离获得7株真菌。扩增出的6个菌株经ITS测序,在NCBI网站上进行基因序列比对,鉴定出其中5株菌株均属于球毛壳菌（Chaetomium globosum）,1株属于子囊菌（As-comycete）。进一步实验表明：分离的菌株多数对组培苗的株高生长影响不大,可初步鉴定其为内生菌,其中的属于球毛壳菌的F和H菌株对无菌苗的株高有明显的促进作用。  相似文献   

17.
Antifungal activity of thiophenes from Echinops ritro   总被引：2，自引：0，他引：2  
Extracts from 30 plants of the Greek flora were evaluated for their antifungal activity using direct bioautography assays with three Colletotrichum species. Among the bioactive extracts, the dichloromethane extract of the radix of Echinops ritro (Asteraceae) was the most potent. Bioassay-guided fractionation of this extract led to the isolation of eight thiophenes. Antifungal activities of isolated compounds together with a previously isolated thiophene from Echinops transiliensis were first evaluated by bioautography and subsequently evaluated in greater detail using a broth microdilution assay against plant pathogens Colletotrichum acutatum, Colletotrichum fragariae, Colletotrichum gloeosporioides, Botrytis cinerea, Fusarium oxysporum, Phomopsis viticola, and Phomopsis obscurans. 5'-(3-Buten-1-ynyl)-2,2'-bithiophen (1), alpha-terthienyl (2), and 2-[pent-1,3-diynyl]-5-[4-hydroxybut-1-ynyl]thiophene (5) at 3 and 30 microM were active against all three Colletotrichum species, F. oxysporum, P. viticola, and P. obscurans.  相似文献   

18.
Three new compounds, (7E)-2beta,3alpha-dihydroxy-megastigm-7-en-9-one (1), 3-[5,7-dihydroxy-2-(4-methoxyphenyl)-4-oxo-4H-chromen-8-yl]-4-methoxybenzoic acid (2), and 4'-O-methyl myricetin 3-O-(6-O-alpha-L-rhamnopyranosyl)-beta-D-glucopyranoside (3), were isolated from Ginkgo biloba, together with 27 known compounds. The structures of the new compounds were determined primarily from 1D- and 2D-NMR analysis. The 4-O-methylbenzoic acid structural feature at C-8 in 2 is encountered for the first time. The antioxidant activities of 29 compounds isolated from Ginkgo biloba were evaluated on intracellular reactive oxygen species in HL-60 cells. It was found that quercetin, kampferol, and tamarixetin had antioxidant activity that was approximately 3-fold greater than that of their respective glycosides and also approximately 3-fold greater than that of a standard ascorbic acid with an IC(50) at maximum effectiveness.  相似文献   

19.
In relation to radial ion transport to xylem vessels in higher plant roots, some features of stele, cortex, and root tip freshly isolated from 2-day-old corn roots grown under moistened or submerged condition were investigated. The contents of P, K, and Mg in primary roots decreased gradually from the apical to the basa1 region axially. The stele contained P, Na, Cu, Fe, and Mn in higher level than the cortex. The O2 uptake rate of root tip was much higher and that of freshly isolated stele was as high as that of fresh cortex. In stele, more CN sensitive respiration was observed than in cortex. Although isolated stele absorbed tess 32p than cortex and root tip, the incorporation of 32p into organic compounds in stele was as much as in root tip. These results show that the freshly isolated stele has high metabolic activity and must play an inherent role in radial and selective ion transport in situ.  相似文献   

20.
Two new dehydromonacolins (1 and 3), together with nine known monacolins (4-12), were isolated from red yeast rice. Compounds 4-6 were isolated from a natural resource for the first time. Their structures were elucidated by means of NMR and mass spectroscopic analyses. The structure of dehydromonacolin N (1) was further confirmed by its semisynthesis from monacolin K (lovastatin) (11). Dehydromonacolin J (2), an intermediate in the semisynthesis of 1, was obtained as a new dehydromonacolin. The structure of dehydromonacolin L (3) was also confirmed by an elimination reaction of monacolin L (12). Compound 1, possessing a C2 side chain, is unprecedented in the natural monacolin family and exhibited moderate cytotoxic activity against Hep G2, Caco-2, and MCF-7 cancer cell lines. Dehydromonacolin K (8) demonstrated the most potent cytotoxicity to all three of these cell lines. The structure-activity relationship of natural and synthesized monacolins was discussed. This is the first report on the cytotoxic effects of dehydromonacolins.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号