印楝素 A 降解动力学研究

研究 pH、水分、紫外光、温度对印楝素 A 稳定性的影响,建立在不同条件下印楝素 A 的一级降解动力学模型。计算印楝素 A 降解反应的反应速率常数、温度效应系数(Q)、活化能(Ea)、活化焓(ΔH)和活化熵(ΔS)。结果表明,印楝素 A 的活化能为 98.49 kJ/mol,活化焓为 95.84 kJ/mol,活化熵为 10.68 kJ/mol · K。印楝素 A 在环境中的降解反应是自发反应,在环境中易自然降解。     

印楝果实成熟期调查及不同采收期印楝素含量的变化

印楝果实的成熟期较长,不同成熟期所采样品的百粒重、印楝素含量和印楝素产量也不相同,调查和实验结果显示：印楝果实的成熟期集中在7月初至9月中旬期间;早期样品的百粒重低而印楝素含量高,后期样品百粒重高而印楝素含量低,成熟率约30%时百粒重和印楝素含量基本稳定,印楝素产量在果实成熟后基本稳定;同一时期采摘的样品中,绿色果皮的样品印楝素含量和产量均高于黄色果皮的样品。     

印楝素对水稻二化螟的生物活性及控制作用

 系统地研究了印楝素对水稻二化螟的生物活性及作用方式。试验结果表明，印楝素乳油对二化螟有胃毒、拒食、忌避、内吸等多种作用方式。0.75和0.50 mg/L印楝素乳油处理茭白饲喂3龄幼虫，幼虫分别于3、6 d内全部死亡；0.375、0.300和0.250 mg/L印楝素乳油低剂量处理茭白饲喂3龄幼虫，幼虫拒食率分别达94.38%、88.74%、80.07%；成虫产卵量分别下降80.70%、62.05%、40.86%。6、3和2 mg/L印楝素乳油处理初孵蚁螟，24 h内死亡率达100%。印楝素乳油对成虫产卵有显著的忌避作用。稻田喷施0.3%印楝素乳油62.5和125 mL/667 m2防治二化螟，21 d保苗效果分别为88.14%和94.13%，防治效果分别为85.36%和90.76%。表明印楝素对二化螟有较高的生物活性和理想的控制效果。     

印楝种仁5种活性成分纯化与定量分析

印楝(Azadirachta indica.A.juss)种仁中含有印楝素A(azadirachtin)等活性成分,主要为四环三萜类化合物,对害虫具有显著的忌避拒食作用和生长抑制作用。本研究通过硅胶柱层析和TLC法对印楝活性物质进行分离纯化,得到印楝素A等5种高纯度印楝素同系物,采用LC-MS对其进行定性分析,鉴定5种物质分别为azadirachtin、salannin、nimbin、6-deacetylnimbin、6-deacetylsalannin,并使用HPLC对5种化合物进行定量分析。     

印楝活性物质超临界CO2萃取技术

印楝(Azadirachta indica A.Juss)种子中含有大量杀虫活性较高的柠檬素类物质,印楝油可促进柠檬素类物质的稳定性和生物活性。本实验通过超临界CO2萃取得到含柠檬素类物质和印楝油混合的粗提物,以印楝素A为检测指标,使用均匀设计优化萃取工艺的压力、温度、时间和夹带剂的体积4个因子,确定最佳提取工艺条件为压力37MPa,温度43℃,时间165min,夹带剂的体积13mL,此时印楝种仁中印楝素A萃取率为0.37%。初步测定超临界CO2萃取产物对玉米象(Sitophilus zeamais Motschulsky)成虫的驱避活性,并对该技术应用于印楝产业化的前景和可行性进行分析探讨。     

水分影响印楝素及同系物降解动力学研究

研究水分对印楝素 A、6-deacetylnimbin、6-deacetylsalannin、nimbin和salannin 5 种同系物稳定性的影响，并建立水分影响印楝素及同系物降解动力学模型。结果表明，水能加快印楝素A及同系物的降解，且降解率随着水分含量的增加而增大。     

印楝幼苗对不同水分和光照条件的生理生态学响应

为了揭示印楝幼苗生长及代谢对不同水分和光照条件的响应规律,以0.5年生印楝半同胞家系实生苗为材料,设置4个水分水平（分别占田间持水量的60%~65%、40%~45%、30%~35%和20%~25%）与3个光照水平（分别是自然光照的100%、75%和50%）共12个组合的盆栽试验,分析不同水分及光照条件下生长指标、形态指标、生理指标及印楝素含量的变化情况。结果表明,自然光照、田间持水量为60%~65%的条件更有利于印楝幼苗的生长,干旱胁迫和遮光对印楝苗高、地径、生物量以及叶片发育均会产生抑制作用,且遮光的抑制程度明显大于干旱;在干旱胁迫条件下,印楝可通过大量合成可溶性蛋白质、游离脯氨酸及可溶性糖等初生代谢产物以及增加根茎比来提高植株干旱适应能力;在遮光条件下,印楝主要初生代谢产物可溶性蛋白质、可溶性糖、游离脯氨酸的合成受阻,其次生代谢产物印楝素的积累减少;在重度干旱胁迫条件下,遮光在一定程度上可以缓解干旱对印楝幼苗生长带来的不利影响;干旱和遮光的交互作用遵循“促进理论”,不支持“独立影响理论”。研究表明,印楝幼苗在生长过程中表现出较大的干旱适应范围及较强的光照依赖性。因此,在幼苗培育过程中要尽可能提供最大光照强度。此外,充足光照条件下适当干旱胁迫有利于印楝初生代谢产物与次生代谢产物的积累,这可作为生产上提高印楝素含量的一个潜在措施。     

几种植物源杀虫剂对螺旋粉虱的生物活性及田间防治效果

采用室内生物测定和大田药效试验等方法,测定印楝素、苦参碱和烟碱对螺旋粉虱的室内生物活性与田间防治效果.结果表明,这3种杀虫剂均对螺旋粉虱具有较高的生物活性.其中在对螺旋粉虱成虫的毒力测定中,印楝素、苦参碱和烟碱LC_(50)值分别为0.0998、0.013 3、0.0023mg/L,对3龄若虫的LC_(50)值分别为1.6724、0.0593、0.031 5mg/L,对卵的LC_(50)值分别为1.2117、0.0340和0.011 3mg/L.大田药效结果表明,3种植物源杀虫剂对螺旋粉虱均有很好的防治效果和持效性,其中在1.00 mg/L的浓度下,药后5 d的防治效果仍在80%左右.     

印楝嫁接技术研究

研究3种嫁接方式(劈接、切接和芽接)以及3种不同砧木大小(小于0.5 cm、0.5～1 cm、1～1.5 cm)和3个不同无性系(LD0505、LD0507和LD0509)对印楝嫁接成活率的影响。结果表明：嫁接方法是影响嫁接成活率的关键因子，其次是砧木的大小，不同无性系对嫁接成活率影响不显著，采用切接和砧木大小为1～1.5 cm时能够提高印楝嫁接成活率，最佳的处理组合是A2B3C2，成活率高达85%。     

用酶联免疫吸附试验法检测印楝愈伤组织中的印楝素含量

用双抗体夹心法酶联免疫吸附试验（ＤＡＳ－ＥＬＩＳＡ）检测印楝（ＡｚｄｉｒａｃｈｔａｉｎｄｉｃａＡ．Ｊｕｕｓｓ）愈伤组织中的印楝素含量,成功建立了ＤＡＳ－ＥＬＩＳＡ,以牛血清蛋白为载体,用二环己基碳二亚胺合成免疫原,制备抗血清,获得效价为１：２５６０,以辣根过氧化物酶为标记酶,用“碘酸盐酸氧化法”合成酶标抗体,使用包被抗体的最适浓度为５．０μｇ／ｍＬ,标记抗体浓度为２．５μｇ／ｍＬ,可测抗原最低浓度     

Mineral composition of some traditional Mexican teas

Teas of plant origin traditionally consumed by the Mountain Pima of Chihuahua, Mexico, were analyzed for mineral nutritional content. Fe, Cu, Zn, Ca, and Mg composition was determined for native teas made from shoots ofTagetes lucida, T. filifolia, Elytraria imbricata, andHolodiscus dumosus, and from root xylem ofCeanothus depressus andPhaseolus ritensis. Native uses of these teas are also described.     

Studies on natural repellents against potato tuber moth (Phthorimaea operculella Zeller) in country stores

Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong (1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage, sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over 45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield of a subsequent crop.     

Comparative Assessment of the Efficacy of Various Nitrogen Fertilizers

Summary

The efficiency of N fertilizers is usually poor; often less than 50% of the applied N is taken up by the crop. This review focuses on various N fertilizers with respect to the significance of different N loss pathways, namely (i) ammonia volatilization, (ii) dinitrogen and nitrogen oxide emissions, and (iii) nitrate leaching. Further, the significance of biological N immobilization, ammonium fixation and, finally, the impact of nitrate vs. ammonium uptake on crop yield are also discussed. The reviewed literature shows that N fertilizers may differ markedly in their susceptibility to losses. There is, however, considerable scope to improve N efficiency of each N source by proper N management practices.     

Redox Status and Neuro Inflammation Indexes in Cerebellum and Motor Cortex of Wistar Rats Supplemented with Natural Sources of Omega-3 Fatty Acids and Astaxanthin: Fish Oil,Krill Oil,and Algal Biomass

Health authorities worldwide have consistently recommended the regular consumption of marine fishes and seafood to preserve memory, sustain cognitive functions, and prevent neurodegenerative processes in humans. Shrimp, crabs, lobster, and salmon are of particular interest in the human diet due to their substantial provision of omega-3 fatty acids (n-3/PUFAs) and the antioxidant carotenoid astaxanthin (ASTA). However, the optimal ratio between these nutraceuticals in natural sources is apparently the key factor for maximum protection against most neuro-motor disorders. Therefore, we aimed here to investigate the effects of a long-term supplementation with (n-3)/PUFAs-rich fish oil, ASTA-rich algal biomass, the combination of them, or krill oil (a natural combination of both nutrients) on baseline redox balance and neuro-inflammation indexes in cerebellum and motor cortex of Wistar rats. Significant changes in redox metabolism were only observed upon ASTA supplementation, which reinforce its antioxidant properties with a putative mitochondrial-centered action in rat brain. Krill oil imposed mild astrocyte activation in motor cortex of Wistar rats, although no redox or inflammatory index was concomitantly altered. In summary, there is no experimental evidence that krill oil, fish oil, oralgal biomass (minor variation), drastically change the baseline oxidative conditions or the neuro-inflammatory scenario in neuromotor-associated rat brain regions.     

Potential of dry fractionation of wheat bran for the development of food ingredients,part II: Electrostatic separation of particles

Wheat bran is a composite material made of several layers, such as pericarp, testa and aleurone. It could be fractionated into purified fractions, which might either be used as food ingredients, or serve as a starting material for extraction of bioactive compounds. The aim of this work was to evaluate the potential of using electrostatic separation as a way to obtain purified fractions from wheat bran. Ultrafine-ground bran obtained either by cryogenic grinding or by grinding at ambient temperature was used as starting material. The ultrafine bran was then charged by tribo-electrification and introduced in a chamber containing two high voltage electrodes, where bran particles were separated depending on their acquired charge, allowing positively and negatively charged fractions to be collected separately. The particle size distribution, microstructure and biochemical composition of the obtained fractions were studied. The charge of the particles was influenced by their biochemical composition: particles rich in highly branched and cross-linked arabinoxylans (pericarp) were separated from particles rich in β-glucan, ferulic acid and para-coumaric acid (aleurone cell walls). The testa and the intracellular compounds from aleurone were not highly charged, neither positively nor negatively. The most positively charged fraction represented 34% of the initial bran, and contained 62% of the ferulic acid present in the initial bran. The yield of the separation process was good (5.4% loss), and could be further increased.     

In vitro antimicrobial activity of different accessions ofSolanum commersonii Dun. from Uruguay

Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds.     

Novel food and non-food uses for sorghum and millets

Sorghum and millets have considerable potential in foods and beverages. As they are gluten-free they are suitable for coeliacs. Sorghum is also a potentially important source of nutraceuticals such antioxidant phenolics and cholesterol-lowering waxes. Cakes, cookies, pasta, a parboiled rice-like product and snack foods have been successfully produced from sorghum and, in some cases, millets. Wheat-free sorghum or millet bread remains the main challenge. Additives such as native and pre-gelatinised starches, hydrocolloids, fat, egg and rye pentosans improve bread quality. However, specific volumes are lower than those for wheat bread or gluten-free breads based on pure starches, and in many cases, breads tend to stale faster. Lager and stout beers with sorghum are brewed commercially. Sorghum's high-starch gelatinisation temperature and low beta-amylase activity remain problems with regard to complete substitution of barley malt with sorghum malt . The role of the sorghum endosperm matrix protein and cell wall components in limiting extract is a research focus. Brewing with millets is still at an experimental stage. Sorghum could be important for bioethanol and other bio-industrial products. Bioethanol research has focused on improving the economics of the process through cultivar selection, method development for low-quality grain and pre-processing to recover valuable by-products. Potential by-products such as the kafirin prolamin proteins and the pericarp wax have potential as bioplastic films and coatings for foods, primarily due to their hydrophobicity.     

<Emphasis Type="Italic">Pulque</Emphasis>, An Alcoholic Drink from Rural Mexico,Contains Phytase. Its <Emphasis Type="Italic">in vitro</Emphasis> Effects on Corn Tortilla

Pulque is made by fermenting the agave sap or aguamiel of Agave atrovirens with a whole array of microorganisms present in the environment including several lactic acid bacteria and yeasts such as Saccharomyces cerevisiae. Ascorbic acid was determined in pulque and aguamiel, respectively. Phytase activity in lees, liquid and freeze-dried pulque was assayed by measuring the appearance of phosphate from phytate by a colorimetric method likewise phosphate from phytate present in fresh corn tortilla was measured after in vitro incubation with pulque. Iron, zinc, calcium, magnesium and selenium contents were measured in pulque and corn tortilla as well as in nixtamalized corn flour (NCF), the latter is used to make instant tortilla, since corn provides most of the energy as well as most of the phytate in the Mexican rural diet. Pulque showed phytase activity but much less ascorbic acid and iron than previously reported; additionally, phytase in pulque hydrolyzed most of phytate’s corn tortilla. Lees, which is mostly made of pulque’s microbiota, significantly accumulated iron and zinc but no selenium. NCF was fortified with iron by the manufacturers but poorly blended. There were significant differences on selenium content between tortillas samples, apparently some soils in central Mexico are selenium deficient. Moderate pulque intake appears to increase the bioavailability of iron and zinc bound by phytate in corn.