葡萄籽中原花青素提取方法优化处理

溶剂提取法是提取葡萄籽原花青素的常用方法 ,然而 ,在不同提取条件下 ,提取效果并不一致。利用水、甲醇、乙醇、丙酮及它们的水溶液提取葡萄籽中的原花青素 ,而后用铁盐催化比色法测原花青素含量 ,考察了提取剂的浓度、粉碎度对提取的影响。在优化处理的基础上 ,获得了有效的提取条件 :葡萄籽粉碎度 10 0目 ,提取剂 70 %甲醇水溶液。     

Antioxidant properties of conjugates of polyethylene glycols containing terpenophenolic fragments

A series of water-soluble conjugates has been synthesized from polyethylene glycols of various lengths and 4-bromomethyl-2,6-diisobornylphenol. The membrane protective and antioxidant activities of the synthesized products were evaluated on the model of the H₂O₂-induced hemolysis of erythrocytes. It was shown that the studied conjugates have a significant antioxidant activity, and a significant membrane protective effect was shown for the conjugates containing 0.2% and 0.8% of the 2,6-diisobornyl-4-methylenephenolic fragments.     

UVB-induced hemolysis of rat erythrocytes: protective effect of procyanidins from grape seeds

Besides erythema and sunburn reactions, UVB stress can promote erythrocyte extravasation from skin capillaries and hemolysis, and photosensitized hemoglobin can in turn lead to an overload of free radicals in dermis which exacerbates photodamage. The objective of this study was to investigate in rat erythrocytes (RBC) the pattern of events leading to membrane peroxidation and hemolysis following UVB insult (1.5-8.5 J/cm2), and the protective action of grape seed procyanidins. UVB causes a dramatic dose-dependent decrease of intracellular glutathione (paralleled by the formation of pro-oxidant ferryl-hemoglobin), of intramembrane vitamin E and of membrane fluidity, then a rise of conjugated dienes (CD), and thiobarbituric acid-reactive substances (TBARS) and finally a strong hemolytic effect. Procyanidins prevent membrane peroxidation (but not intracellular GSH depletion nor ferryl-hemoglobin formation), with a minimal effective concentration of 0.1 microM (IC50 for TBARS and CD after 120 min UVB exposure: 0.71 microM and 0.56 microM) and dose-dependently delay the onset of hemolysis, by 30 min at 0.1 mciroM, by 90 and 120 min at 0.5 and 1.0 microM. Epigallocatechin-3-O-gallate (EGCG) and catechin, typical constituents of the fraction, were significantly less potent. This since procyanidins (1 microM) inhibit the formation of phospholipid hydroperoxides of the inner (phosphatidylserine, phosphatidylethanolamine) and outer (phosphatidylcholine) layers of the RBC membrane (HPLC analysis), suppress the decrease in membrane fluidity due to lipid and protein thiol oxidation and spare vitamin E from consumption in a dose-dependent manner (0.1-1 microM). Hence procyanidins, preserving membrane phospholipids, since their strong antilipoperoxidant activity, may maintain in vivo the integrity of RBC in sub-epidermal capillaries and effectively counteract in dermis the onset/exacerbation of the UVB-induced skin photodamage.     

Synthesis and antiproliferative activity of novel steroidal dendrimer conjugates

We describe the synthesis of steroidal dendrimer conjugates of first and second generation with tetramethylene core and 5-hydroxy-isophtalic acid dimethyl ester as branching unit modified to incorporate ethynylestradiol or 17α-estradiol as terminal units. The steroidal dendrimer conjugates, the free drug (steroids) and dendrimer were tested against a panel of cancer cell lines (CEM, MCF7, HeLa) and normal human fibroblast (BJ). The steroidal dendrimer conjugates of first generation exhibited cytotoxic activity and induced apoptosis in chronic leukemia (CEM) as resultant activation of caspase cascade which is mainly provoked in G2/M arrested cells.     

Antioxidant and antiproliferative activity of curcumin semicarbazone

A new semicarbazone derivative of curcumin (CRSC) was synthesized and examined for its antioxidant, antiproliferative, and antiradical activity and compared with those of curcumin (CR). The antioxidant activity was tested by their ability to inhibit radiation induced lipid peroxidation in rat liver microsomes. The antiproliferative activity was tested by studying the in vitro activity of CRSC against estrogen dependant breast cancer cell line MCF-7. Kinetics of reaction of (2,2'-diphenyl-1-picrylhydrazide) DPPH, a stable hydrogen abstracting free radical was studied to measure the antiradical activity using stopped-flow spectrophotometer. Finally one-electron oxidized radicals of CRSC were generated and characterized by pulse radiolysis. The results suggest that the probable site of attack for CRSC is both the phenolic OH and the imine carbonyl position. CRSC shows efficient antioxidant and antiproliferative activity although its antiradical activity is less than that of CR.     

Changes and importance of oligomeric procyanidins during maturation of grape seeds

Flavans and procyanidins from the seeds of different grape varieties were separated and identified using HPLC techniques. The compounds identified were (+)-catechin and (?)-epicatechin, dimeric procyanidins B1, B2, B3 and B4, trimeric procyanidin C2 and gallic acid. During maturation of the grape berries, the flavan-3-ol content fell in the seeds whereas procyanidin levels increased. This suggests an interrelationship between the compounds. There was also evidence of varietal differences in the amounts of phenolic compounds in grape seeds.     

野生葡萄及葡萄酒抗氧化活性和抗菌性研究

选取广西、湖南等地野生葡萄,与经典酿酒葡萄比较,研究抗氧化活性和活性物质,同时监测葡萄酒发酵过程中各指标的动态变化,并对不同品种葡萄酒的抗菌性进行研究。结果表明:赤霞珠的酚类含量和抗氧化活性高于野生葡萄和玫瑰香葡萄,但野生葡萄酒的抗菌性能显著优于赤霞珠和玫瑰香葡萄酒。葡萄酒在发酵过程中其抗氧化活性和酚类物质含量均随发酵过程的进行而升高;总抗氧化活性与总酚含量、氧自由基清除能力与原花青素含量成显著正相关,相关系数均大于0.989;总花色苷含量在发酵初期上升,后期下降,葡萄酒颜色变浅。     

Antioxidant and antiproliferative activities of hydroxyl-substituted Schiff bases

Eight hydroxyl-substituted Schiff bases with the different number and position of hydroxyl group on the two asymmetric aromatic rings (A and B rings) were prepared by the reaction between the corresponding aromatic aldehyde and aniline. Their antioxidant effects against the stable galvinoxyl radical (GO) in ethyl acetate and methanol, and 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH)-induced DNA strand breakage, and their antiproliferative effects on human hepatoma HepG2 cells, were investigated. Structure–activity relationship analysis demonstrates that o-dihydroxyl groups on the aromatic A ring and 4-hydroxyl group attached to the aromatic B ring contribute critically to the antioxidant and antiproliferative activities.     

Design and multi-step synthesis of chalcone-polyamine conjugates as potent antiproliferative agents

The aim of this study is to synthesize chalcone-polyamine conjugates in order to enhance bioavailability and selectivity of chalcone core towards cancer cells, using polyamine-based vectors. 3-hydroxy-3′,4,4′,5′-tetramethoxychalcone (1) and 3′,4,4′,5′-tetramethoxychalcone (2) were selected as parent chalcones since they were found to be efficient anti-proliferative agents on various cancer cells. A series of ten chalcone-polyamine conjugates was obtained by reacting carboxychalcones with different polyamine tails. Chalcones 1 and 2 showed a strong cytotoxic activity against two prostatic cancer (PC-3 and DU-145) and two colorectal cancer (HT-29 and HCT-116) cell lines. Then, chalcone-spermine conjugates 7d and 8d were shown to be the most active of the series and could be considered as promising compounds for colon and prostatic cancer adjuvant therapy.     

Antioxidant properties of 3-hydroxycoumarin derivatives

A series of hydroxylated 3-hydroxycoumarins was synthesised by the reaction of 3-aryl-2-hydroxypropenoic derivatives with boron tribromide. They were evaluated for their ability to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical, the superoxide anion radical, the hydroxyl radical and the peroxynitrite anion and to inhibit copper-induced human LDL peroxidation. The physicochemical results were in accordance to establish the compounds hydroxylated on C-6 and C-7 positions as the most active of the series with antioxidant potencies comparable to those of quercetin and vitamin C. These compounds form o- and p-quinonoid derivatives upon radical scavenging and may serve as new lead compounds for pharmacological investigations.     

Flavan-3-ol and procyanidin glycosides from quercus miyagii

A chemical examination of the leaves and bark of Quercus miyagii has led to the isolation and characterization of two flavan-3-ol glycosides and two procyanidin rhamnosides in which the sugar residue is located at C-3.     

Synthesis and properties of oligodeoxyribonucleotide-polyethylene glycol conjugates.

Pools of oligonucleotide conjugates consisting of 10-400 different molecular species were synthesized. The conjugates contained a varying number of ethylene glycol units attached to 3'-terminal, 5'-terminal and internal positions of the oligonucleotides. Conjugate synthesis was performed by phosphoramidite solid phase chemistry using suitably protected polyethylene glycol phosphoramidites and PEG-derivatized solid supports containing polydisperse PEGs of various molecular weight ranges. The pools were analyzed and fractionated by chromatographic and electrophoretic techniques, and the composition of isolated conjugates was revealed by matrix-assisted laser desorption/ionization mass spectrometry. The number and attachment sites of coupled ethylene glycol units greatly influence the hydrophobicity of the conjugates, as well as their electrophoretic mobilities. Conjugation had little effect on the hybridization behavior of oligonucleotide conjugates with unmodified complementary oligonucleotide strands. Melting temperatures were between 67 and 73 degrees C, depending on the size and number of coupled PEG chains, compared to 68 degrees C for the unmodified duplex. Conjugates with PEG coupled to both 3'- and 5'-terminal positions showed a more than 10-fold increase in exonuclease stability.     

Preparation and properties of amphipathic enzyme-polymer conjugates.

Five uncoupled mutant strains of Escherichia coli carrying mutations in the uncD gene have been studied. In each of these mutant strains the beta-subunit of the F1 portion of the membrane-bound adenosine triphosphatase is abnormal. In one of the mutant strains (carrying the uncD12 allele) in F1-ATPase aggregate was formed which was purified and found to have low ATPase activity. ATPase activity was absent in the other four strains and the abnormal beta-subunits were tightly bound to the membranes. However, membranes from these strains exhibited various proton permeabilities as indicated by NADH-dependent atebrin-fluorescence quenching and bound different amounts of normal F1-ATPase. The amounts of reconstitution of energy-linked reactions after the addition of normal F1-ATPase also varied depending on the mutant allele. It is apparent that considerable phenotypic variations can occur between strains carrying mutations in the same unc gene.     

Synthesis and hybridization properties of the conjugates of oligonucleotides and stabilization agents. Part 3

New compounds having tri- or pentamethylenamine linker functions were synthesized. These derivatives were covalently attached through the 5'-phosphoramide linkage to heptanucleotide pd(CCAAACA). Complementary complexes of the octanucleotide pd(TGTTTGGC) and above oligonucleotide conjugates were tested for their thermodynamic response. The T(m) data and thermodynamic parameters for complex formation confirmed the ability of chromone (gamma-pyrone) derivatives to stabilize strongly the 7-mer/8-mer complementary complex. Moreover, benzochromone (naphthopyrane) and, surprisingly, tetrahydropyrimidinethanone derivatives showed the capacity of stabilizing this 7-mer/8-mer complementary complex. The effect of all these compounds on the stability of the oligonucleotide complexes (DeltaDeltaG at 37 degrees C ranged from -1.2 to -2.0 kcal/mol) was shown to be comparable to the effect of one nucleotide base pair and similar to the effect (DeltaDeltaG at 37 degrees C ranged from -1.5 to -2.0 kcal/mol) found for acridine-oligonucleotide conjugates, which served as a reference in this study.     

The preparation and properties of novel reversible polymer-protein conjugates. 2-omega-Methoxypolyethylene (5000) glycoxymethylene-3-methylmaleyl conjugates of plasminogen activators

The preparation of a reagent capable of reversibly attaching polyethylene glycol to proteins and the use of this material in modifying the plasminogen activators urokinase- and tissue-type plasminogen activator are described. The characterisation and the reversible nature of these protein-polymer conjugates are discussed, and some of the in vitro properties of these modified enzymes are explored.     

Antioxidant capacity of a 3-deoxyanthocyanidin from soybean.

Soybean cotyledons directly exposed to UV-C (190-280 nm) contained a colored pigment in those areas of the epidermis directly exposed to UV-C. Ethanolic extracts from UV-C irradiated cotyledons showed a significant peak at 532 nm at pH=10, but not seen at pH=6, successive changes in pH were accompanied by reversible changes in the spectra. The identity of the pigment isolated from soybean cotyledons was established as apigeninidin by comparing the features of standard of a apigeninidin (from sorghum) previously characterized by FAB-MS, UV, HPLC, 1H NMR, and IR spectroscopy. To characterize antioxidant activity of this compound, its ability to scavenge radical species in vitro was tested. In the concentration range tested (up to 200 microg ml (-1)), apigeninidin did not show any scavenger activity towards hydroxyl radical, quinones or NO. However, ascorbyl radical and lipid radicals were effectively quenched in a dose-dependent manner. Overall, UV-C radiation triggers molecular signals that lead in soybean cotyledons to the synthesis and accumulation of an antioxidant pigment, apigeninidin, that shows scavenger activity against ascorbyl and lipid radicals in in vitro studies.     

Tyrosinase catalysed biphenyl construction from flavan-3-ol substrates

Mushroom tyrosinase catalysed oxidation of three flavan-3-ols, viz. catechin, fisetinidol and mesquitol, was conducted to construct biphenyl bonds. Exposure of the flavan-3-ols to tyrosinase and subsequent trapping of the o-quinone intermediates resulted in the formation of novel flavan-3-ol derivatives, the structures of which were elucidated by mono- and two-dimensional 1H-NMR experiments. Application of the methodology resulted in the improved synthesis of the natural flavan-3-ol dimer, mesquitol-[5-->8]-catechin, previously isolated from Prosopis glandulosa.     

Antioxidant and antiproliferative activity of glycosides obtained by biotransformation of xanthohumol

The biotransformation of xanthohumol (1), a prenylated chalcone isolated from hops by selected fungi, was investigated. Microbial regioselective glycosylation at the C-4′ position led to xanthohumol 4′-O-β-d-glucopyranoside (2) and xanthohumol 4′-O-β-d-(4′′′-O-methyl)-glucopyranoside (3). The subsequent cyclization of 2 resulted in isoxanthohumol 7-O-β-glucopyranoside (4). The structures of the products were identified based on spectroscopic methods. The biological activity of isolated metabolites has been evaluated. Compared to xanthohumol (1), metabolite 2 is a better 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenger, while 2 and 3 have stronger antiproliferative activity against the human HT-29 colon cancer cell line.