超临界流体萃取-反相高效液相色谱法测定玉米蛋白粉中叶黄质和玉米黄质的含量

研究了超临界流体萃取（SFE）玉米蛋白粉中类胡萝卜素的提取工艺及其收率,结果显示：当45℃,26 MPa,改性剂体积分数为10%-20%,CO2流量为80-120 L/h,动态提取3 h时,类胡萝卜素的收率达到9%;用反相高效液相色谱法（RP-HPLC）测定了3种单体胡萝卜素（叶黄质、玉米黄质和β-胡萝卜素）的含量,其中叶黄质0.023%,玉米黄质0.004 2%,β-胡萝卜素0.0015%.同时还与万寿菊提取物中叶黄质含量（0.068%）进行了比较.

黄斑部色素——叶黄质的研究进展

黄斑部色素具有滤过蓝光和辅助色彩感知的作用，并可减少色彩失真和增加视敏度。目前已知叶黄质是黄斑部的主要色素，主司黄色觉，包括叶黄素和玉米黄质。叶黄质的抗氧化能力与其对短波长光的捕获力相结合后，可保护外层视网膜、视网膜色素上皮层和脉络膜毛细血管免受氧化损伤。本文就近年来对黄斑部色素——叶黄质的基础和流行病学研究作一综述。

不同类型枇杷果实着色期间果肉类胡萝卜素含量的变化

【目的】分析不同类型枇杷果实着色过程中果肉类胡萝卜素的变化特点,探讨果肉外观颜色差异形成的原因。【方法】以‘大红袍’、‘青种’分别代表红沙和白沙两类不同枇杷品种,自果实开始着色起,分期采样,进行枇杷果肉类胡萝卜素提取、纯化和HPLC分析。【结果】果实进入着色期后,果肉叶黄质含量迅速下降,至果实成熟时下降平缓,而α-胡萝卜素、β-胡萝卜素、β-隐黄质和玉米黄素成分均呈上升趋势,尤其在采收前7～14d上升迅速。果实成熟后,‘大红袍’果肉的类胡萝卜素总量为‘青种’的2倍以上;两品种果肉叶黄素类色素含量接近,但类胡萝卜素含量差异较大,‘大红袍’的胡萝卜素含量是‘青种’的4倍左右。【结论】胡萝卜素积累的多少,尤其是β-胡萝卜素含量的高低是造成‘青种’和‘大红袍’果肉类胡萝卜素总量积累差异的主要原因,也是影响这两个品种果肉色泽深浅的主要因素。

白果中类胡萝卜素的分析与鉴定

目的 : 对白果中类胡萝卜素进行分析与鉴定。方法 : 可见光吸收光谱特性分析证实白果中色素成分为类胡萝卜素 ;比色法测定了其含量 ;分别采用薄层色谱和高效液相色谱分离白果中类胡萝卜素 ,并鉴定其成分及组成。结果 : 白果中含类胡萝卜素总量约 489μg/1 0 0 g;其中叶黄质、β-胡萝卜素和 α-胡萝卜素 ,分别占总类胡萝卜素的 6 9.2 0 %、1 5 .80 %和 7.45 %。结论 :白果含大量类胡萝卜素 ,以叶黄质为主 ,其次为 β-和 α-胡萝卜素。

羊踯躅花期花瓣类胡萝卜素的含量变化

为揭示羊踯躅的花瓣花色形成机理和花色新品种选育提供参考。以羊踯躅花发育的4个时期花瓣为材料,采用高效液相色谱法(HPLC法)测定4种类胡萝卜素的含量,并分析其变化规律。结果表明,高效液相色谱法可以对羊踯躅花瓣中的叶黄质、玉米黄质、α-胡萝卜素和β-胡萝卜素完全分离并进行分析。羊踯躅在花蕾期已经有大量类胡萝卜素积累。β-胡萝卜素在花发育过程中,其含量远高于α-胡萝卜素、叶黄质和玉米黄质,α-胡萝卜素的含量在整个花发育过程中含量均较低;β-胡萝卜素随着花的发育,其含量先降后升,在盛开期达到最高(95.25μg/g FW),占检测类胡萝卜素总量的92.89%;叶黄质和玉米黄质则相反,先升后降,在花朵膨大期含量最高(48.15μg/g FW和18.71μg/g FW),分别占检测类胡萝卜素总量的42.18%和16.39%,在盛开期含量均较低。认为β-胡萝卜素是影响羊踯躅花瓣着色的一个主要因素,其含量变化与羊踯躅的花色形成密切相关。

Xanthophyll Cycle and Its Molecular Mechanism in Photoprotection

When plants absorb more light than that can be used for photosynthesis, the excessive energy can cause photoinhibition and even photooxidation of photosynthetic apparatus. Xanthophyll cycle-dependent photo-protection is believed to be the main mechanism for plants to deal with excessive light energy. This review focuses on molecular biological aspects and regulations of violaxanthin de-epoxidase and zeaxanthin epoxidase involved in xanthophyll cycle. We will summarize the functions of xanthophyll cycle, especially recent advances in its thermal dissipation mechanism of photoprotection. Some interesting issues deserving further study will be discussed.

Cloning and Expression Analysis of Violaxanthin De-Epoxidase (VDE) cDNA in Wheat

Violaxanthin de-epoxidase (VDE) is the key enzyme in the xanthophyll cycle and protects plant photosynthetic apparatus from the damage of excessive light. A wheat (Triticum aestivum L cv. Xiaoyan 54) VDE cDNA was obtained using RT-PCR method. Its deduced protein sequence shares high identity with that of Arabidopsis and rice. Southern blot revealed that there are three copies of VDE gene per haploid genome of wheat. VDE transcript levels were higher in green leaf than in root, seed and etiolated leaf. Northern blotting analysis indicated that VDE mRNA level is induced during greening process of etiolated wheat seedling and increased by intense light illumination.

Changes in Violaxanthin Deepoxidase Activity and Unsaturation of Thylakoid Membrane Lipids in Indica and Japonica Rice Under Chilling Condition and Strong Light

To explore the differences of sensitivities to chilling and strong light in indica and japonica rice (Oryza sativa L), the changes in unsaturation of thylakoid membrane lipids and xanthophyll cycle were studied under chilling condition and strong light. The contents of unsaturated fatty acids of thylakoid membrane lipids decreased and that of the saturated ones increased with the time of chilling and strong light treatment, resulting in the reduction of the index of unsaturation of fatty acids (IUFA). The activity of violaxanthin deepoxidase (VDE), a key enzyme of xanthophyll cycle, also reduced. The content of violaxanthin (V) increased, and the contents of antheraxanthin (A) and zeaxanthin M decreased, the ratio of (A+Z)/ (A+Z+V) decreased correspondingly. Arrhenius analysis showed that VDE was sensitive to both chilling and unsaturation level of thylakoid membrane lipids. Correlation analysis showed that there was distinctly positive relationships between IUFA of thylakoid membrane lipids and the activity of VDE, Fv/Fm, and D, protein content. Lower IUFA values, less fluidity and stability of thylakoid membrane lipids, lower VDE activity and (A+Z)/(A+Z+V) ratio were found in indica rice cv. Shanyou 63 than in japonica rice cv. 9516 under chilling and strong light.

PURIFICATION OF FLAVONES OF GINKGO LEAVES BY ADSORPTION HZ-841 RESIN

The purification process of total flavones of ginkgo leaves by resin HZ-841 from ethanol extract was studied. First, the total flavone was extracted from the defatted powder of ginkgo L. biloba leaves. Effects of solvents and operation conditions were examined to get a relative high yield and purity in this step. The crude extract was further purified by resin HZ-841. Both adsorption and elution process were studied to obtain an optimized conditions, i.e., pH, flow rate, concentration. A yellow powder was obtained, of which 37.3% was flavones, obviously higher than the basic international standard of 24%.

Photosynthetic Pigments Affected by Fertilizer Source in Four Brassica Vegetables

Effect of fertilizer source （mineral fertilizer or organic manure） on photosynthetic pigments leaves content of four brassica vegetables （Pak choi, Kohlrabi, Cauliflower and Cabbage） was tested. Among treatments, cauliflower fertilized with chicken manure had the highest content of chlorophyll a and b （10.08 and 9.37 μm·g^-1）, while, pak choi had the lowest values （2.00 and 2.44 μm·g^-1） in non-fertilized plants. These differences in chlorophyll a and b content may have a great impact on photosynthetic rate and activity. Total carotenoids and total xanthophylls （lutein, zeaxanthin, antheraxanthin and violaxanthin） were the highest in cauliflower while the lowest was in pakchoi, β-carotene, on the other hand, was the highest percentage of total carotenoids （65.7%） in pak choi while Kohlrabi had the lowest percent （57.4%）. This high percentage offl-carotene of total carotenoids may compensate for lower content of chlorophylls and assist for efficient light harvesting process. Lutein showed to be the major components of xanthophyll pigments brassica vegetables and ranged from 0.462μm·g^-1 in cabbage to 0.626μm·g^-1 in kohlrabi but not differed significantly which may refer to genetically controlled. However, lutein, antheraxanthin and zeaxanthin content were increased significantly by the application of chicken manure regardless ofbrassica vegetable type. Violaxanthin was only detected in pak choi and not affected by fertilizer source. It can be concluding from the increasing contents of total xanthophylls pigments that may increase photosynthetic efficiency through non-photochemical quenching process.

Inhibitory Effect of Isorhapontigenin on Copper-Mediated Peroxidation of Human Low-Density Lipoprotein in vitro

Aim To study the effect of Isorhapontigenin (Iso) on copper-mediatedperoxidation of human low-density lipoprotein (LDL) and on the toxicity of oxidized LDL (ox-LDL) tomouse macrophages in vitro. Methods Human LDL from sera df normal lipidemic donors was separated bysequential ultracentrifugation. The separated human IDL 1 mg·mL^(-1) in phosphate buffer saline, pH7.4, was incubated with cupric sulfate (10 μmol·L^(-1) ) at 37℃ for 10 h in the presence orabsence of various concentrations of Iso. Malondialdehyde (MDA) formation, vitamin E consumption,electrophoretic mobility of LDL, mitochondria] membrane potential of mouse peritoneal macrophages,phagocytosis of neutral red, and release of nitric oxide (NO) from macrophages were determined byvarious methods. Results Iso 1 - 100 μmol·L^(-1) significantly inhibited the increase of MDAformation, vitamin E consumption and electrophoretic mobility of LDL induced by Cu^(2+) in aconcentration-dependent manner. The injury of the mitochondrial membrane potential of mouseperitoneal macrophages due to incubation with ox-LDL (0.1 mg·mL^(-1)) at 37℃ for 12 h was markedlyprotected by 10 μmol·L^(-1) Iso. After pretreat-ment of the macrophages with 10 μmol · L^(-1)of Iso and then exposure to ox-LDL for 4 h, the reduction of phagocytosis of neutral red and releaseof NO in response to lipopolysaccharide (IPS) stimulation were significantly prevented. ConclusionIso has protective action against Cu^(2+) - mediated LDL peroxidation and ox-LDL induced toxicity tomacrophages in vitro.

Assessing the dynamics of chromophoric dissolved organic matter(CDOM) in the Yellow Sea and the East China Sea in autumn by EEMs-PARAFAC

In this study we have successfully characterized the fluorescent components of chromophoric dissolved organic matter(CDOM) in the Yellow Sea and the East China Sea in autumn using excitation-emission matrix fluorescence spectroscopy(EEMs) combined with parallel factor analysis(PARAFAC).PARAFAC aids the characterization of fluorescence CDOM by decomposing the fluorescence matrices into individual components.Four humic-like components(C1,C2,C3,and C4),one marine biological production component(C6),and two protein-like components(C5 and C7) were identified by PARAFAC.We researched the distributional patterns of fluorescence intensity,regression analyses between salinity,chlorophyll a concentration and fluorescence intensities of individual fluorophore,and regression analysis between salinity and fluorescence intensities percent of individual fluorophore.The results revealed that C2 and C4 showed conservative mixing behavior,while C1 and C3 possessed conservative mixing behavior in high salinity region and additional behavior in low and middle salinity region,which were considered to be derived from riverine and degradation of organic matter from resuspended and/or sinking particles and show non-conservative mixing behavior.In addition to riverine sources,the tryptophan-like C5 may receive widespread addition(likely from photo-degradation or biodegradation),while the most likely sources for the one marine humic-like C6 and tyrosine-like C7 were biological activity and microbial processing of plankton-derived CDOM,which were suggested to be of autochthonous origin and biologically labile.The application of EEM-PARAFAC modeling presents a unique opportunity to observe compositional changes,different mixing behavior and temporal variability in CDOM in the Yellow Sea and the East China Sea.

Iron Mobilization and Mineralogical Alterations Induced by Iron-Deficient Cucumber Plants (Cucumis sativus L.) in a Calcareous Soil

Dicotyledons cope with ion(Fe) shortage by releasing low-molecular-weight organic compounds into the rhizosphere to mobilize Fe through reduction and complexation mechanisms. The effects induced by these root exudates on soil mineralogy and the connections between Fe mobilization and mineral weathering processes have not been completely clarified. In a batch experiment, we tested two different kinds of organic compounds commonly exuded by Fe-deficient plants, i.e., three organic acids(citrate, malate, and oxalate)and three flavonoids(rutin, quercetin, and genistein), alone or in combination, for their ability to mobilize Fe from a calcareous soil and modify its mineralogy. The effect of root exudates on soil mineralogy was assessed in vivo by cultivating Fe-deficient and Fe-sufficient cucumber plants(Cucumis sativus L.) in a RHIZOtest device. Mineralogical analyses were performed by X-ray powder diffraction. The batch experiment showed that citrate and, particularly, rutin(alone or combined with organic acids or genistein)promoted Fe mobilization from the soil. The combinations of rutin and organic acids modified the soil mineralogy by dissolving the amorphous fractions and promoting the formation of illite. These mineralogical alterations were significantly correlated with the amount of Fe mobilized from the soil. The RHIZOtest experiment revealed a drastic dissolution of amorphous components in the rhizosphere soil of Fe-deficient plants, possibly caused by the intense release of phenolics, amino acids, and organic acids, but without any formation of illite. Both batch and RHIZOtest experiments proved that exudates released by cucumber under Fe deficiency concurred to the rapid modification(on a day-scale) of the mineralogy of a calcareous soil.