用大孔树脂纯化栀子黄色素的研究

为降低栀子黄色素中栀子苷的含量,提高栀子黄色素稳定性,该文就10种大孔树脂纯化栀子黄色素进行了研究。结果表明,A-5大孔树脂选择性吸附藏花素的能力较强,吸附率和解吸率均达85%以上,经其纯化后的栀子黄色素OD值比率(即栀子苷在最大吸收波长238 nm处的吸光值与藏花素在最大吸收波长440 nm处的吸光值的比值)可降至0.4以下,实现了对藏花素与栀子苷的有效分离,适于栀子黄色素的纯化。     

Assessment of pro-oxidant activity of foods by kinetic analysis of crocin bleaching

The pro-oxidant activity of potent oxidants and foods was determined using the kinetic analysis of crocin bleaching. In its reduced form, crocin has an absorption band at 443 nm, which disappears upon oxidation by a generic radical species. Hydroxyl radicals generated by hydrogen peroxide, peroxyl radicals from ABAP, and the stable free radical DPPH(*) were allowed to react with crocin in an aqueous solution at 40 degrees C. Pro-oxidant activity was taken as the ratio between the decrease in crocin absorbance at 5 min and the relevant oxidant concentration. The test proposed was used to evaluate the pro-oxidant activity of widely consumed foods such as pasteurized skim milk and bread. They both exerted significant pro-oxidant activities, which were attributed to the early nonenzymatic browning products formed upon heat treatment.     

Bioavailability, distribution, and antioxidative effects of selected triterpenes in mice

This study analyzed the content of eight triterpenes (oleanolic acid, ursolic acid, arjunolic acid, asiatic acid, boswellic acid, corosolic acid, madecassic acid, and maslinic acid) in ten vegetables and eight fruits. These compounds at 0.5% were supplied to mice for 4 or 8 weeks. The bioavailability, tissue distribution, and antioxidative protection of these triterpenes were examined. Results showed that triterpenes were detected in eight vegetables and six fruits. Basil and brown mustard contained seven test triterpenes, in the range of 14-102 mg/100 g dry weight. The level of each triterpene in plasma, brain, heart, liver, kidney, colon, and bladder increased as the feeding period was increased from 4 weeks to 8 weeks (P < 0.05). Renal homogenates from mice with triterpene intake had greater antioxidative effects against glucose-induced glutathione loss and malondialdehyde and oxidized glutathione production when compared with those from control groups (P < 0.05). These data support that these triterpenes were absorbed and deposited in their intact forms, which in turn exerted in vivo antioxidative protection.     

Effect of pH and temperature on comparative antioxidant activity of nonenzymatically browned proteins produced by reaction with oxidized lipids and carbohydrates

The antioxidative activity of nonenzymatically browned bovine serum albumin (BSA) produced by reaction with ribose (RI), hydroperoxides of methyl linoleate oxidation (HP), and secondary products of methyl linoleate oxidation (SP), at different pHs (4, 7, and 10) and temperatures (25, 37, 50, 80, and 120 degrees C), was studied to compare the antioxidative effects of carbohydrate- and oxidized lipids-modified proteins. The modified proteins (RIBSA, HPBSA, and SPBSA) were tested for antioxidative activity (at 100 ppm) in soybean oil using the thiobarbituric acid-reactive substances (TBARS) assay. All of them decreased significantly (p < 0.05) the TBARS formation in the oil and exhibited different effectiveness as a function of the temperature and the pH of the medium. In addition, there was a good correlation between the antioxidative activity of the protein and the amino acid losses produced during the nonenzymatic browning. These results are in agreement with an analogous and complimentary contribution of both Maillard and oxidized lipid/protein reactions to the antioxidative activity produced in foods during processing and storage.     

Evaluation of antioxidant activity of some natural polyphenolic compounds using the Briggs-Rauscher reaction method

A new method based on the inhibitory effects of antioxidants on the oscillations of the hydrogen peroxide, acidic iodate, malonic acid, and Mn(II)-catalyzed system (known as the Briggs-Rauscher reaction), was used for the evaluation of antioxidative capacity. With this method, which works near the pH of the fluids in the stomach (pH approximately 2), a group of natural compounds present in fruits and vegetables or in medicinal plants assumed to have antioxidant capacity, was tested successfully. The aim of the present study is to evaluate the antioxidative properties of some active principles contained in vegetables and aromatic plants, namely, cynarin (from Cynara scolymus), rosmarinic acid (from Rosmarinus officinalis), echinacoside (from Echinacea species), puerarin (from Pueraria lobata), and oleuropein (from Olea europea). Also studied with the Briggs-Rauscher reaction method was the antioxidant activity of cyanidin 3-O-beta-glucopyranoside (from Citrus aurantium) in order to compare the results with those obtained by other methods. The conclusions on the dependency of the antioxidative activity on the pH of the testing system are given.     

Antioxidant properties of aroma compounds isolated from soybeans and mung beans

Aroma compounds contained in the extracts of soybean and mung bean that possess antioxidant activity were identified by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The major aroma constituents of soybeans were 1-octen-3-ol (13.699 ppm), maltol (1.662 ppm), phenylethyl alcohol (1.474 ppm), hexanol (1.430 ppm), and gamma-butyrolactone (1.370 ppm). The major aroma constituents of mung beans were hexanol (3.234 ppm), benzyl alcohol (2.060 ppm), gamma-butyrolactone (1.857 ppm), 2-methyl-2-propenal (1. 633 ppm), and pentanol (1.363 ppm). The major aroma chemicals of soybeans and mung beans were examined for antioxidative activities in two different assays. Eugenol, maltol, benzyl alcohol, and 1-octen-3-ol showed potent antioxidative activities in two different assays. Eugenol, maltol, benzyl alcohol, and 1-octen-3-ol inhibited the oxidation of hexanal by 100%, 93%, 84%, and 32%, respectively, for a period of 40 days at the 500 microg/mL level. Eugenol, maltol, benzyl alcohol, and 1-octen-3-ol inhibited malonaldehyde (MA) formation from cod liver oil by 91%, 78%, 78%, and 78%, respectively, at the 160 microg/mL level. The antioxidative activity of eugenol was comparable to that of the natural antioxidant alpha-tocopherol (vitamin E).     

Changes produced in the antioxidative activity of phospholipids as a consequence of their oxidation

The antioxidative activities of native and oxidized soybean phosphatidylcholine (PC), phosphatidylthanolamine (PE), and phosphatidylinositol (PI) in the protection of soybean oil heated in the dark under air at 60 degrees C were studied in an attempt to clarify the consequences that phospholipid oxidation has on antioxidative activities. The three native phospholipids protected the oil when assayed at 200 ppm, and phospholipid oxidation decreased the antioxidative activity of both PC and PI. However, slightly oxidized PE was more antioxidative than native PE, most likely as a consequence of the formation by amino-carbonyl reactions of pyrrolized phospholipids, which were determined and for which antioxidative properties are known. Nevertheless, further increases in PE oxidation produced a decrease in its antioxidative activity. These results suggest that two opposite reactions are competing in the antioxidative activity of amino phospholipids upon oxidation: fatty acid chain oxidation, which decreases phospholipid antioxidative activity, and amino-carbonyl reactions, which produce derivatives with antioxidant properties. This last property may be useful to increase the antioxidative activity of commercial lecithins containing amino phospholipids.     

Gas-liquid chromatographic determination of thiabendazole and methyl 2-benzimidazole carbamate in fruits and crops.

A method is described for the electron capture gas-liquid chromatographic determination of thiabendazole and methyl 2-benzimidazole carbamate (MBC) after derivatization with pentafluorobenzyl bromide (PFB-Br). The samples are extracted with ethyl acetate, and the residual thiabendazole, benomyl, and MBC are isolated by liquid-liquid extraction into dilute HCl. After neutralization and re-extraction with ethyl acetate, thiabendazole and MBC are reacted with PFB-Br to form the PFB derivatives. Alumina column chromatography was used to clean up extracts, and the derivatives could be detected as low as 5-10 pg. Recoveries were 95-98% from fruits fortified with 0.3-2.0 ppm thiabenzadole; recoveries were 91-97% when 0.05-1.0 ppm benomyl/MBC were added to fruits/crops. The PFB derivatives were identified by gas-liquid chromatography-mass spectrometry.     

Coffee drinking influences plasma antioxidant capacity in humans

Coffee and tea are widely consumed beverages, but only tea has been studied for its antioxidant capacity (AC) in vivo. The aim of this study was to compare the capacities of coffee and tea to affect plasma redox homeostasis in humans. The AC of plasma before and after supplementation with 200 mL of beverages (0, 1, and 2 h) was measured by the TRAP and crocin tests. The crocin test detected an increase in plasma AC only in subjects supplemented with coffee (+7% at peak time), whereas the TRAP method showed an increase in plasma AC after consumption of both coffee and tea (+6 and +4%, respectively, at peak time). Both beverages induced a significant increase in plasma uric acid (+5 and +7%, respectively). Uric acid strongly affects the results obtained by the TRAP test and does not affect those obtained by the crocin test. We can thus argue that uric acid is the main component responsible for the plasma AC increase after tea drinking, whereas molecules other than uric acid (probably phenolic compounds) are likely to be responsible for the increase in plasma AC after coffee drinking.     

Antioxidant properties of green tea extract protect reduced fat soft cheese against oxidation induced by light exposure

The effect of two different antioxidants, EDTA and green tea extract (GTE), used individually or in combination, on the light-induced oxidation of reduced fat soft cheeses (0.2 and 6% fat) was investigated. In samples with 0.2% fat, lipid hydroperoxides as primary lipid oxidation products were not detected, but their interference was suggested from the formation of secondary lipid oxidation products such as hexanal and heptanal. The occurrence of these oxidation markers was inhibited by spiking with 50 ppm EDTA or 750 ppm GTE, or a combination of the two prior to irradiation. In contrast, addition of 50 ppm EDTA to samples with 6% fat was ineffective, but 750 ppm GTE (alone or in combination with EDTA) strongly reduced levels of hexanal and heptanal. Accumulation of primary lipid hydroperoxides was not affected by GTE, hence antioxidative activity was ascribed to scavenging of hexanal and heptanal precursors. These radical intermediates result from hydroperoxide disintegration, and subsequent scavenging by GTE, which acts as a radical sink, corroborates the intense signal observed by electron paramagnetic resonance (EPR) spectroscopy.     

辐射诱变选育栀子新品系

为选育产量高、活性物质含量高、抗逆性强的栀子新品种,选取现有本地栀子种质资源中表现较好的类型的枝条,利用60Co γ射线进行辐射诱变处理,然后将优选的株系通过扦插繁殖、栽培,经过多年的稳定和筛选,选育出了具有树型适中、分枝匀称、冠形圆满、花果期集中、结实量多、果实大、果实中栀子苷与色素含量高、抗寒、适应性强等特点的新品系——天顺栀子。经急性毒性试验,结果表明该新品系与普通栀子一样安全无毒性。     

Preparation and promotion of fruit growth in kiwifruit of fluorinated N-phenyl-N'-1,2,3-thiadiazol-5-yl ureas

Seventeen phenyl-fluorinated analogues of thidiazuron [N-phenyl-N'-(1,2,3-thiadiazol-5-yl)urea, TDZ] have been prepared and characterized. The effects of each fluorinated urea on growth and quality of kiwifruits (Actinidia deliciosa) were evaluated by comparison with untreated (control) and TDZ-treated fruits. The results obtained showed a clear dependence of the growth-promoting activity of these fluorinated ureas on the pattern and degree of fluorine substitution in the phenyl ring. The most effective for promoting fruit growth was N-(2,3,5,6-tetrafluorophenyl)-N'-(1',2',3'-thiadiazol-5'-yl)urea at 25 ppm (at harvest, treated fruits were 58% heavier than untreated ones) followed by N-(3,5-difluorophenyl)-N'-(1',2',3'-thiadiazol-5'-yl)urea at 10 ppm (50%). Comparatively, TDZ-treated fruits were 31% (10 ppm) and 38% (25 ppm) heavier than untreated ones. The results also indicate that the effects of the more active phenyl-fluorinated ureas on some standard quality parameters of fruits, for example, percent of fruit dry matter content, soluble solids contents, total titratable acids, shape, and internal structure, are similar to those of TDZ. Quantitative structure-activity relationships have been derived for the fruit growth promoting activity of the phenyl-fluorinated analogues of TDZ.     

Larvicidal activity of isobutylamides identified in Piper nigrum fruits against three mosquito species

The insecticidal activity of materials derived from the fruits of Piper nigrum against third instar larvae of Culex pipiens pallens, Aedes aegypti, and A. togoi was examined and compared with that of commercially available piperine, a known insecticidal compound from Piper species. The biologically active constituents of P. nigrum fruits were characterized as the isobutylamide alkaloids pellitorine, guineensine, pipercide, and retrofractamide A by spectroscopic analysis. Retrofractamide A was isolated from P. nigrum fruits as a new insecticidal principle. On the basis of 48-h LC(50) values, the compound most toxic to C. pipiens pallens larvae was pipercide (0.004 ppm) followed by retrofractamide A (0.028 ppm), guineensine (0.17 ppm), and pellitorine (0.86 ppm). Piperine (3.21 ppm) was least toxic. Against A. aegypti larvae, larvicidal activity was more pronounced in retrofractamide A (0.039 ppm) than in pipercide (0.1 ppm), guineensine (0.89 ppm), and pellitorine (0.92 ppm). Piperine (5.1 ppm) was relatively ineffective. Against A. togoi larvae, retrofractamide A (0.01 ppm) was much more effective, compared with pipercide (0.26 ppm), pellitorine (0.71 ppm), and guineensine (0.75 ppm). Again, very low activity was observed with piperine (4.6 ppm). Structure-activity relationships indicate that the N-isobutylamine moiety might play a crucial role in the larvicidal activity, but the methylenedioxyphenyl moiety does not appear essential for toxicity. Naturally occurring Piper fruit-derived compounds merit further study as potential mosquito larval control agents or as lead compounds.     

Rapid photometric assay evaluating antioxidative activity in edible plant material.

The objective of the present study is to develop a rapid and convenient method to determine antioxidative activity. It was determined by the inhibition capacity on the hemoglobin-catalyzed peroxidation of linoleic acid. The appropriate conditions for reaction of 4 mM linoleic acid were 0.002% hemoglobin at 37 degrees C for 10 min. Adding methanol to the reaction mixture at <20% showed no significant effect on the peroxidation of linoleic acid. Products formed from hemoglobin-catalyzed peroxidation of linoleic acid were 9- and 13-hydroperoxyoctadecadienoic acid at a ratio of approximately 50:50. Eight synthetic antioxidants were assayed for their antioxidative activity; all of them showed linear response to the logarithm of their concentration. Antioxidative activity from different plant samples was also examined. Tea, ginger, chrysanthemum, and roselle showed higher antioxidative activity. Either hydrophobic or hydrophilic antioxidants were able to be assayed with this method within 15 min.     

Antioxidative activity in the pericarp and seed of Japanese pepper (Xanthoxylum piperitum DC)

The antioxidative activity of the dried pericarp and seed of Japanese pepper was studied. The ethyl acetate extract from the pericarp and the methanol extract from the seed showed strong antioxidative activity against linoleic acid by the ferric thiocyanate and thiobarbituric acid (TBA) methods. Japanese pepper contained 3.9 and 2.9 mg/100 g of dry weight (dw) of tocopherols in the pericarp and seed, respectively, alpha-Toc in the former constituting 82% of total tocopherol and gamma-Toc in the latter constituting 96%. Arbutin and magnoflorine were isolated as antioxidants and their chemical structures determined by instrumental analyses. The contents of arbutin evaluated as the trifluoroacetate derivative by GC-MS were 35 and 3.0 mg/100 g of dw in the pericarp and seed, respectively. Magnoflorine was present only in the seed, and not in the pericarp. Both arbutin and magnoflorine exhibited antioxidative activity against linoleic acid and radical-scavenging activity against the DPPH radical.     

Analysis of methoxyfenozide residues in fruits, vegetables, and mint by liquid chromatography-tandem mass spectrometry (LC-MS/MS)

Methoxyfenozide [3-methoxy-2-methylbenzoic acid 2-(3,5-dimethylbenzoyl)-2-(1,1-dimethylethyl) hydrazide; RH-2485], in the formulation of INTREPID, was applied to various crops. Analysis of methoxyfenozide was accomplished by utilizing liquid-liquid extraction and partitioning, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Method validations for fruits, vegetables, and mint are reported. Methoxyfenozide mean recoveries ranged from 72 to 129% over three levels of fortification. The overall average of mean recoveries is 97 +/- 10%. The limit of quantitation for fruits, artichoke, cucumber, squash, and refined sugar was 0.010 ppm, with a detection limit of 0.005 ppm. For all other crops, the limit of quantitation was 0.050 ppm, with a detection limit of 0.025 ppm. No residues were found greater than the limit of quantitation in control samples. Residues above the limit of quantitation were found in all matrices except refined sugar. Foliage (bean, beet, pea, and radish) had greater residue levels of methoxyfenozide residue than their corresponding roots or pods. Other crop matrices contained <1.0 ppm of methoxyfenozide except artichoke, which had a mean of 1.10 ppm.     

栀子黄脂质体的制备、表面修饰及体外消化稳定性研究

为了制备栀子黄脂质体,以栀子黄色素为研究对象,采用乙醇注入法制备栀子黄脂质体,以栀子黄包封率(EE)为指标,通过响应面法优化制备栀子黄脂质体的反应参数,并通过Zeta电位与平均粒径、傅里叶红外光谱(FT-IR)和透射电子显微镜(TEM)等技术对其结构与形态进行表征。采用壳聚糖对栀子黄脂质体进行表面修饰,通过分析经紫外光照射、加热和体外模拟消化等处理后脂质体中的Zeta电位、平均粒径及释放率等指标的变化,研究壳聚糖修饰栀子黄脂质体的稳定性。结果表明,最优反应条件为:搅拌温度51.5℃,卵磷脂与胆固醇质量比5.2∶1,缓冲液体积为32.4 mL,所得栀子黄脂质体EE为78.36%。根据Zeta电位与平均粒径、FT-IR及TEM分析结果可知,已成功制备未修饰栀子黄脂质体与壳聚糖修饰栀子黄脂质体,其平均粒径从203.77 nm增加至282.17 nm。紫外光照射、加热和体外模拟消化试验结果表明,壳聚糖修饰脂质体的稳定性明显高于未修饰脂质体。本研究可为水溶性类胡萝卜素脂质体的制备及应用提供一定的理论依据。     

Inhibition of lipid peroxidation by Lactobacillus acidophilus and Bifidobacterium longum.

The inhibition of lipid peroxidation by Lactobacillus acidophilus and Bifidobacterium longum was investigated using two lipid model systems. All eight strains, including six strains of L. acidophilus and two strains of B. longum, demonstrated an inhibitory effect on linoleic acid peroxidation. The inhibitory rates on linoleic acid peroxidation ranged from 33 to 46% when 1 mL of intracellular cell-free extract was tested. In the second model system, the cell membrane of osteoblast was used as the source for biological lipid. The results indicated that all strains were able to protect biological lipids from oxidation. The inhibition rates on cell membrane lipid peroxidation ranged from 22 to 37%. The effect of L. acidophilus and B. longum on inhibition of fluorescent tissue pigment accumulation was also obtained for osteoblastic cells. The inhibition rates on fluorescent tissue pigment accumulation ranged from 20 to 39%. The antioxidative effect of each milliliter of intracellular cell-free extract of L. acidophilus and B. longum was equivalent to 104-172 ppm of butylated hydroxytoluene (BHT). These results indicated that all strains demonstrated high antioxidative activity. The scavenging ability of lipid peroxidation products, tert-butyl hydroperoxide and malondialdehyde, was also evaluated. The results showed that L. acidophilus and B. longum were not able to scavenge the tert-butyl hydroperoxide. Nevertheless, malondialdehyde was scavenged well by these strains.     

Thin layer chromatographic detection and indirect gas chromatographic determination of three carbamate pesticides.

Carbamate pesticide residues are extracted from vegetables and fruits with methylene chloride. The extracts are spotted on silica gel plates and the pesticides are detected by an enzymatic inhibition technique. For quantitative determination, aliquots of the methylene chloride extracts are evaporated to dryness in a rotary evaporator. After the residues are dissolved in ethanol, 0.5N NaOH is added in the hydrolysis step. To remove a number of possible interferences the hydrolyzed phenols are steam-distilled and treated with 1-fluoro-2,4-dinitrobenzene and/or 4-chloro-alpha,alpha,alpha-trifluoro-3,5-dinitrotoluene to form the ether derivatives. Efficiency in the conversion of the phenolic moieties to the phenyl ethers is about 100%. The resulting electron-capturing derivatives enable the carbamate pesticides to be detected in vegetables and fruits at the 0.05 ppm level. Recoveries of 90-94% were obtained from vegetables and fruits fortified with 0.5-2.0 ppm carbaryl, Mesurol, and propoxur.     

Antioxidative activity of microencapsulated gamma-oryzanol on high cholesterol-fed rats

The effectiveness of microencapsulated gamma-oryzanol (M-gamma-OZ) was evaluated as an antioxidant in Sprague-Dawley rats. Lard containing 100 ppm of gamma-OZ (HCD III) or 100 ppm of M-gamma-OZ (HCD IV) was heated in an oven for 7 days, and the heat-treated lard as an ingredient in a high cholesterol diet (HCD) formulation was tested for analyzing in vivo cholesterol and lipid profiles. The HCDs containing fresh lard (HCD I) and heat-treated lard (HCD II) were fed to the rats for 4 weeks as control groups A and B, respectively, in this experiment. The liver thiobarbituric acid reactive substances values of group C (fed with HCD III) and group D (with HCD IV) were significantly lower (p < 0.05) than that of negative control, group B. One of the cholesterol oxidation products, 7-ketocholesterol, was not detected from group D, indicating that microencapsulation preserved antioxidative activity effectively. The levels of serum total cholesterol and lipoproteins, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein were also affected by heat-induced lipid oxidation.The M-gamma-OZ evidently decreased LDL-cholesterol content and increased HDL-cholesterol in blood samples of tested rats. These results suggested that the M-gamma-OZ was not only effective in inhibiting the hypercholesterolemia of serum and liver but also reduced the oxidation degree of lipids and cholesterol. Therefore, this microencapsulation can be a good potential technique to protect the antioxidant activity of gamma-OZ from heat-induced lipid oxidation.