Separation of C-glycoside flavonoids from Aleurites moluccana using chitin and full N-acetylated chitin

This paper describes a comparative study using different chromatographic supports (fully N-acetylated chitin, chitin and silica gel) to separate the flavonoids swertisin and 2"-O-rhamnosylswertisin from Aleurites moluccana. The results show that the flavonoids have apparently been separated by the hydrogen bond between the stationary phase (chitin and chitin-100) and flavonoids under the conditions studied.     

Separation of bioactive biflavonoids from Rheedia gardneriana using chitosan modified with benzaldehyde

This paper shows the influence of benzenic groups on the chitosan surface for the separation of bioactive biflavonoids from Rheedia gardneriana leaves The yield of the biflavonoids using chitin modified with benzaldehyde (CH-Bz) as adsorbent in column chromatography was higher than that achieved with silica gel and chitosan. The presence of benzenic groups decreases the polarity of chitosan and consequently the interaction of hydrogen bonding between phenolic hydroxyl (OH) of biflavonoids and amine groups of the adsorbent. Therefore, the separation of these compounds appears to be the result of hydrophobicity and pi-pi interaction among electrons from the aromatic ring in sorbent and biflavonoid molecules.     

Separation of lysozyme using superparamagnetic carboxymethyl chitosan nanoparticles

Functionalized Fe(3)O(4) nanoparticles conjugated with polyethylene glycol (PEG) and carboxymethyl chitosan (CM-CTS) were developed and used as a novel magnetic absorbing carrier for the separation and purification of lysozyme from the aqueous solution and chicken egg white, respectively. The morphology of magnetic CM-CTS nanoparticles was observed by transmission electron microscope (TEM). It was found that the diameter of superparamagnetic carboxymethyl chitosan nanoparticles (Fe(3)O(4) (PEG+CM-CTS)) was about 15 nm, and could easily aggregate by a magnet when suspending in the aqueous solution. The adsorption capacity of lysozyme onto the superparamagnetic Fe(3)O(4) (PEG+CM-CTS) nanoparticles was determined by changing the medium pH, temperature, ionic strength and the concentration of lysozyme. The maximum adsorption loading reached 256.4 mg/g. Due to the small diameter, the adsorption equilibrium of lysozyme onto the nanoparticles reached very quickly within 20 min. The adsorption equilibrium of lysozyme onto the superparamagnetic nanoparticles fitted well with the Langmuir model. The nanoparticles were stable when subjected to six repeated adsorption-elution cycles. Separation and purification were monitored by determining the lysozyme activity using Micrococcus lysodeikticus as substrate. The lysozyme was purified from chicken egg white in a single step had higher purity, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Considering that the superparamagnetic nanoparticles possess the advantages of high efficiency, cost-effectiveness and excellent binding of a larger amount of lysozyme and easier separation from the reaction system, thus this type of superparamagnetic nanoparticles would bring advantages to the conventional separation techniques of lysozyme from chicken egg white.     

Geranyl flavonoids from the leaves of Artocarpus altilis

Five geranyl dihydrochalcones, 1-(2,4-dihydroxyphenyl)-3-{4-hydroxy-6,6,9-trimethyl-6a,7,8,10a-tetrahydro-6H-dibenzo[b,d]pyran-5-yl}-1-propanone (2), 1-(2,4-dihydroxyphenyl)-3-[3,4-dihydro-3,8-dihydroxy-2-methyl-2-(4-methyl-3-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (4), 1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methyl-2-(3,4-epoxy-4-methyl-1-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (5), 1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methyl-2-(4-hydroxy-4-methyl-2-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone (8), and 2-[6-hydroxy-3,7-dimethylocta-2(E),7-dienyl]-2',3,4,4'-tetrahydroxydihydrochalcone (9), along with four known geranyl flavonoids (1, 3, 6, 7), were isolated from the leaves of Artocarpus altilis. Their structures were established by spectroscopic means and by comparison with the literature values. Compounds 2, 4, and 9 exhibited moderate cytotoxicity against SPC-A-1, SW-480, and SMMC-7721 human cancer cells.     

Antioxidant flavonoids from leaves of Polygonum hydropiper L

Ten flavonoid compounds were isolated from the dried leaves of Polygonum hydropiper L. (Laksa leaves), and identified as 3-O-alpha-L-rhamnopyranosyloxy-3',4',5,7-tetrahydroxyflavone; 3-O-beta-D-glucopyranosyloxy-4',5,7-trihydroxyflavone; 6-hydroxyapigenin; 6"-O-(3,4,5-trihydroxybenzoyl) 3-O-beta-D-glucopyranosyloxy-3', 4', 5, 7-tetrahydroxyflavone; scutillarein; 6-hydroxyluteolin; 3',4',5,6,7-pentahydroxyflavone; 6-hydroxyluteolin-7-O-beta-D-glucopyranoside; quercetin 3-O-beta-D-glucuronide; 2"-O-(3,4,5-trihydroxybenzoyl) quercitrin; quercetin. Evaluation of the antioxidative activity, conducted in vitro, by using electron spin resonance (ESR) and ultraviolet visible (UV-vis) spectrophotometric assays, showed that these isolated flavonoids possess strong antioxidative capabilities. Measurement of the Trolox equivalent antioxidant capacity (TEAC) values, against ABTS (2,2'-azinobis(3-ethyl-benzo-thiazoline-6-sulphonic acid) radicals and phenyl-tert-butyl nitrone (PBN) azo initiator (AI) also showed strong anti-oxidative activity. The most powerful of the antioxidants was 2"-O-(3,4,5-trihydroxybenzoyl) quercitrin (galloyl quercitrin). A combination of two flavonoid compounds was tested for synergistic anti-oxidative capacity, but no significant improvement was observed.     

Proteinase inhibitor synthesis in tomato leaves : induction by chitosan oligomers and chemically modified chitosan and chitin

Soluble chemical derivatives of chitin and chitosan including ethylene glycol chitin, nitrous acid-modified chitosan, glycol chitosan, and chitosan oligomers, produced from chitosan by limited hydrolysis with HCl, were found to possess proteinase inhibitor inducing activities when supplied to young excised tomato (Lycopersicon esculentum var Bonnie Best) plants. Nitrous acid-modified chitosans and ethylene glycol chitin exhibited about 2 to 3 times the activity of acid hydrolyzed chitosan and 15 times more activity than glycol chitosan. The parent chitin and chitosans are insoluble in water or neutral buffers and cannot be assayed. Glucosamine and its oligomers from degree of polymerization = 2 through degree of polymerization = 6 were purified from acid-fragmented chitosan and assayed. The monomer was inactive and dimer and trimer exhibited weak activities. Tetramer possessed higher activity and the larger pentamer and hexamer oligomers were nearly as active as the total hydrolyzed mixture. None of the fragments exhibited more than 2% acetylation (the limits of detection). The contents of the acid-fragmented mixture of oligomers was chemically N-acetylated to levels of 13% and 20% and assayed. The N-acetylation neither inhibited nor enhanced the proteinase inhibitor inducing activity of the mixture. These results, along with recent findings by others that chitinases and chitosanases are present in plants, provide further evidence for a possible role of soluble chitosan fragments as signals to activate plant defense responses.     

红花桑寄生枝叶总黄酮提取工艺

以Al(NO3)3显色法于510nm测定红花桑寄生枝叶提取液的吸光度,聚酰胺提纯,以芦丁为标准计算含量,正交实验方法探讨以乙醇为溶剂提取该类化合物的最佳工艺条件,结果表明,桑寄生叶最佳提取条件是溶剂为70％乙醇、料液比1：35、80℃条件下提取3h;桑寄生枝的最佳提取条件是溶剂为50％乙醇、料液比1：15、80℃条件下提取3h,在对应条件下桑寄生总黄酮平均得率叶为9.47%,枝为5.25%。     

Antimicrobial and antioxidant properties of chitosan enzymatically functionalized with flavonoids

Chitosan fibres were grafted with flavonoids using tyrosinase to produce reactive o-quinones which subsequently react with primary amino groups of the chitosan. The reaction mechanism using chemically different flavonoids (flavanols, flavonols, flavone, flavanone, isoflavone) was followed by UV/vis spectroscopy and the successful grafting was demonstrated by ATR-IR spectroscopy, pH potentiometric titration and reflectance measurements. An increase of antioxidant activity of functionalized chitosan fibres using well established methods was found depending on the type of the flavonoid used. In addition, some flavonoids increased antimicrobial activity of chitosan against Bacillus subtillis and Pseudomonas aeruginosa.     

油橄榄叶中橄榄苦苷的分离纯化

考察了6种不同大孔树脂对橄榄苦苷的吸附,筛选出吸附选择性好的D101大孔吸附树脂为实验材料.得到的D101大孔树脂的最佳吸附条件:试样上样质量浓度41.06[J].,流速5 mL/min,50％乙醇溶液洗脱,洗脱液用量260mL,树脂可以反复使用.经大孔树脂富集后,橄榄苦苷的纯度可达55％以上,再经葡聚糖凝胶精纯化后,可达76％以上.     

Separation of coeliac-active peptides from bread wheat with the aid of methylpyrrolidinone chitosan

Gliadin-derived peptides from haxaploid wheat, known to be toxic for in-vitro cultured small-intestinal mucosa from coeliac patients, are very active in agglutinating K562(S) cells. Chromatographic data obtained with the use of methylpyrrolidinone chitosan coupled to Sepharose-6B indicate that a minor (1·3%) fraction of the peptides binds very strongly to the support at nearly neutral pH values, and can be eluted at pH 2·85. This fraction is the one responsible for the agglutination of K562(S) cells, being one-hundred times more active than the digest from which it has been separated.     

Separation of modified 2'-deoxyoligonucleotides using ion-pairing reversed-phase HPLC

A group of 18-mers of the same base sequence, but with differing alkyl modifications is used to investigate effects of these modifications on retention of oligonucleotides using ion-pairing reversed-phase liquid chromatography (IP-RPLC). It is shown that IP-RPLC is able to distinguish between oligonucleotides differing only by a single alkyl group. The identity of the nucleobase and position and length of the alkyl adduct affect retention of the oligonucleotide. These separation phenomena result from changes in charge and hydrophobicity upon alkylation. As demonstrated in this paper; chromatographic selectivity, unique to IP-RPLC, greatly facilitates the purification process of modified oligonucleotides.     

Three new flavonoids from the leaves of oriental tobacco and their cytotoxicity

Three new flavonoids, 6,7-dimethoxy-4′-hydroxy-8-formylflavon (1), 8-formyl-4′,6,7-trimethoxyflavon (2), 4′,7-dihydroxy-8-formyl-6-methoxyflavon (3), together with fifteen known flavonoids (4–18) were isolated from the leaves of oriental tobacco (a variety of Nicotiana tabacum L). Their structures were determined by means of HRESIMS, extensive 1D and 2D NMR spectroscopic studies and chemical evidences. The cytotoxicity against five human tumor (NB4, A549, SHSY5Y, PC3, and MCF7) cell lines of compounds 1–3 were also evaluated. The results showed that compounds 1 and 3 showed high cytotoxicity against PC3 and A549 cell lines with IC₅₀ values of 2.6 and 1.6 μM, respectively.     

Separation and identification of major plant sphingolipid classes from leaves

Sphingolipids are major components of the plasma membrane, tonoplast, and other endomembranes of plant cells. Previous compositional analyses have focused only on individual sphingolipid classes because of the widely differing polarities of plant sphingolipids. Consequently, the total content of sphingolipid classes in plants has yet to be quantified. In addition, the major polar sphingolipid class in the model plant Arabidopsis thaliana has not been previously determined. In this report, we describe the separation and quantification of sphingolipid classes from A. thaliana leaves using hydrolysis of sphingolipids and high performance liquid chromatography (HPLC) analysis of o-phthaldialdehyde derivatives of the released long-chain bases to monitor the separation steps. An extraction solvent that contained substantial proportions of water was used to solubilized >95% of the sphingolipids from leaves. Neutral and charged sphingolipids were then partitioned by anion exchange solid phase extraction. HPLC analysis of the charged lipid fraction from A. thaliana revealed only one major anionic sphingolipid class, which was identified by mass spectrometry as hexose-hexuronic-inositolphosphoceramide. The neutral sphingolipids were predominantly composed of monohexosylceramide with lesser amounts of ceramides. Extraction and separation of sphingolipids from soybean and tomato showed that, like A. thaliana, the neutral sphingolipids consisted of ceramide and monohexosylceramides; however, the major polar sphingolipid was found to be N-acetyl-hexosamine-hexuronic-inositolphosphoceramide. In extracts from A. thaliana leaves, hexosehexuronic-inositolphosphoceramides, monohexosylceramides, and ceramides accounted for approximately 64, 34, and 2% of the total sphingolipids, respectively, suggesting an important role for the anionic sphingolipids in plant membranes.     

Synthesis and properties of chitosan hydrogels modified with heterocycles

Preparation and properties of chitosan modified with heterocycles in absence or presence of gluteraldehyde as a cross linker is described. New modified chitosan–heterocyclic hydrogels were prepared from chitosan and heterocyclic compounds such as N,N′-biisomaleimide, N,N′-biisophthalimide, and N,N′-phthalimidomaleimide via a crosslinking reaction. The new hydrogels chemical structure was characterized by spectral analysis (IR), X-ray diffraction, thermal gravimetric analysis (TGA), solubility, and swellability in water and different organic solvents. Evaluation of the efficiency of the new hydrogels to uptake copper and cobalt ions from aqueous systems was carried out and promising results were obtained.     

十二烷基硫酸钠辅助提取布渣叶中的黄酮类物质

以布渣叶为研究体系,采用表面活性剂辅助热回流法提取黄酮类物质.考察了表面活性剂种类及浓度、提取时间、液固比和溶剂pH等因素,并通过实验数据进行了正交试验设计,得到最优的工艺条件:表面活性剂选择十二烷基硫酸钠(SDS),质量浓度0.8 g/L,提取时间105 min,液固比45 mL/g,溶剂pH 6.3.在此条件下,布渣叶黄酮得率为15.73％,与其他方法相比具有显著优势.     

Measurement of chlorophyll fluorescence within leaves using a modified PAM Fluorometer with a fiber-optic microprobe

By using a fiber-optic microprobe in combination with a modified PAM Fluorometer, chlorophyll fluorescence yield was measured within leaves with spatial resolution of approximately 20 m. The new system employs a miniature photomultiplier for detection of the pulse-modulated fluorescence signal received by the 20 m fiber tip. The obtained signal/noise ratio qualifies for recordings of fluorescence induction kinetics (Kautsky effect), fluorescence quenching by the saturation pulse method and determination of quantum yield of energy conversion at Photosystem II at different sites within a leaf. Examples of the system performance and of practical applications are given. It is demonstrated that the fluorescence rise kinetics are distinctly faster when chloroplasts within the spongy mesophyll are illuminated as compared to palisade chloroplasts. Photoinhibition is shown to affect primarily the quantum yield of the palisade chloroplasts when excessive illumination is applied from the adaxial leaf side. The new system is envisaged to be used in combination with light measurements within leaves for an assessment of the specific contributions of different leaf regions to overall photosynthetic activity and for an integrative modelling of leaf photosynthesis.This paper is dedicated to Ulrich Heber on the occasion of his 65th birthday, with great respect for his outstanding achievements in photosynthesis research.     

黑老虎叶总黄酮提取工艺及其抗氧化活性研究

为探讨超声波辅助提取黑老虎叶总黄酮的最佳提取工艺条件及其抗氧化活性,该文以黑老虎叶为研究对象,采用超声波提取法提取黑老虎叶总黄酮,通过单因素试验研究提取时间、乙醇浓度、提取温度、料液比对黑老虎叶总黄酮提取率的影响在单因素试验的基础上,采用正交试验优化其提取工艺条件,测试了最优条件下提取的黑老虎叶总黄酮对DPPH自由基、·OH自由基及超氧阴离子的清除能力。结果表明:黑老虎叶总黄酮超声辅助提取最佳提取条件为提取时间35 min、乙醇浓度80%、提取温度50℃、料液比1:20g·mL^-1最佳条件下提取率为4.83%。抗氧化活性测试结果显示,黑老虎叶总黄酮表现出较好的清除DPPH自由基、·OH自由基及超氧阴离子能力,其抗氧化能力为清除DPPH自由基能力>清除超氧阴离子能力>清除·OH自由基能力。在浓度为0.8 mg·mL^-1时,黑老虎叶总黄酮清除DPPH自由基、·OH自由基及超氧阴离子的能力相当于同浓度下Vc的97.6%、82.1%、95.5%,黑老虎叶总黄酮是天然抗氧化剂的良好来源。上述结果为黑老虎叶活性成分的提取及开发利用提供了理论基...