HPLC—ELSD测定饮料中果糖、葡萄糖、蔗糖和乳糖的含量

为建立一种简便、准确、灵敏测定饮料中果糖、葡萄糖、蔗糖和乳糖含量的高效液相色谱蒸发光散射检测方法。使用Phenomenex-NH2(250 mm×4.6 mm,5 μm)色谱柱分离,以乙腈∶水(80∶20,V∶V)为流动相,流速为1.5 mL/min,ELSD为检测器,漂移管温度45℃,N2流量3.5 bar。结果表明：果糖、葡萄糖、蔗糖、乳糖在50～2 000 μg/mL内呈良好线性关系,4种糖的回收率均为96.1%～100.4%,测定的相对标准偏差为0.2%～0.9%。此方法操作简便、快捷、准确,用于实际样品的测定后,获得了令人满意的结果。     

新型苯并咪唑类化合物 对棉花枯萎病菌的毒力测定

采用菌落直径法,测定了12种新型苯并咪唑类化合物对棉花枯萎病菌的抑菌活性。结果表明:在测定浓度为200 μg/mL的情况下,12种新型苯并咪唑类化合物对棉花枯萎病菌的抑菌率达32.5%～89.45%。其中,化合物N-(3-甲基苄基)-1H-苯并咪唑、N-(3-氯苄基)-1H-苯并咪唑、N-(3-溴苄基)-1H-苯并咪唑对棉花枯萎病菌的抑菌率较高,分别为80.1%、89.45%、80.3%,它们对棉花枯萎病菌的EC50值分别为66.1 μg/mL、38.1 μg/mL、86.3 μg/mL,具有良好的抑菌活性;其他9种化合物抑菌活性均低于80%。     

高效液相色谱测定木薯块根β-胡萝卜素的方法优化

为确定高效液相色谱法测定木薯β-胡萝卜素的最佳方法,以丙酮/石油醚(2/5,V/V)为提取液,甲醇/叔丁基甲醚(70/30,V/V)为流动相,对白心木薯SC101和蛋黄木薯SC9块根β-胡萝卜素保留时间及其分离情况进行研究。检测条件为：色谱柱YCM C30,柱温30℃,流速为1 mL/min等度洗脱。结果显示：该方法精确度和重复性的变异系数均小于5%,保留时间为12.65 min,在2～30 μg/mL浓度范围内线性关系良好(y= 209.11x－14.114,R2＝0.9993);平均回收率为81%～92 %。采用改进的HPLC法对木薯块根β-胡萝卜素进行测定,数据稳定性好,分析时间比已报道的方法缩短30 min以上,适用于快速定量分析木薯块根的微量β-胡萝卜素含量。     

大麦籽粒中4种主要黄酮类化合物的HPLC测定方法研究

为给大麦主要黄酮类化合物含量的快速测定及开发利用提供依据,对利用高效液相色谱技术(HPLC)分离和同时测定大麦中黄酮类化合物儿茶素、杨梅素、槲皮素、山奈酚含量的方法进行了研究.结果表明,采用HPLC同时测定4种大麦黄酮类化合物的优化色谱条件为:YMC-Pack ODS AM-303 (5 μm, 250 mm_4.6 mm i.d.)色谱柱;流动相A-0.1%冰乙酸水溶液,B-乙睛,梯度洗脱;流速0.8 mL/min,进样量10 μL.儿茶素、杨梅素、槲皮素、山奈酚分别在0.063～2.000 μg (R2=0.9999)、0.034～1.100 μg (R2=0.9998)、0.025～0.800 μg (R2=0.9993)、0.018～0.560 μg (R2=0.9995)成良好的线性关系,加样回收率分别为96.88%(RSD=1.30%)、98.30%(RSD=0.57%)、96.29%(RSD=1.20%)、101.59%(RSD=0.73%). 测定方法简便、快捷,结果准确、重复性好,可用于大麦4种主要黄酮类化合物的同时测定.     

11种植物提取物对4种病原细菌的抑菌活性筛选

采用琼脂扩散法初步测试11种植物提取物对魔芋软腐病菌(Erwinia carotovora pv. carotovora)、猕猴桃溃疡病菌(Pseudomonas syringae pv. actinidiae)、白菜软腐病菌(Erwinia carotorora)、核桃细菌性黑斑病菌(Xanthomonas campestris pv.juglandis)4种病原细菌的抑制活性，进一步采用二倍稀释法测定高抑菌活性物质的最低抑菌浓度(MIC)，旨在为植物源杀细菌剂的研发提供线索。测定结果表明，1 000 μg/mL剂量下，大黄、博落回和狼毒提取物对魔芋软腐病菌具有较强抑制活性，对猕猴桃溃疡病菌抑制作用最好的是博落回和大黄提取物，对核桃黑斑抑菌效果最好的是蛇床提取物，均优于或相当于农用链霉素200 μg/mL的效果；二倍稀释法测试表明，大黄和博落回提取物对魔芋软腐病菌的MIC值分别为7.8、15.6 μg/mL；大黄和博落回提取物对猕猴桃溃疡病菌的MIC值分别为3.9、15.6 μg/mL。说明大黄、博落回和狼毒提取物均具有显著抑制植物病原细菌的活性，有开发为新型植物源杀细菌剂的潜力。     

人参中腐霉利农药残留量测定研究

目的建立气相色谱—质谱联用法(GC—MS)测定人参中腐霉利的方法。方法样品用乙腈提取,通过预先装有净化材料的分散固相萃取净化管中,涡旋使充分混匀,再置振荡器上剧烈振荡使净化完全,然后经气相色谱-质谱法分析腐霉利的残留量,以外标法定量。结果腐霉利(速克灵)质量浓度在0.008～0.2μg范围内时,线性关系良好,相关系数r为0.99997,检出限为0.005μg/mL。称取人参样品平行6份,分别加入一定量腐霉利标准溶液(0.02μg/mL),按方法步骤处理测定,计算回收率在78.83%～96.21%范围内,相对标准偏差为3.96%。结论该方法可适用于人参中腐霉利残留量的检测。     

QuEChERS-高效液相色谱-串联质谱法测定柑橘中13种磺酰脲类除草剂残留

建立了基于QuEChERS(快速Quick、简单Easy、廉价Cheap、有效Effective、耐用Rugged、安全Safe)前处理技术和高效液相色谱-串联质谱法同时测定柑橘中13种磺酰脲类除草剂的分析方法。通过对提取溶剂、净化剂、色谱条件、质谱条件等进行优化,确定样品用乙腈提取,经QuEChERS方法净化后,以0.1%甲酸水溶液和甲醇作为流动相,用Hypersil GOLD C18色谱柱(1.9μm 2.1mm×100mm)进行梯度洗脱分离,在高效液相色谱-电喷雾串联质谱仪正离子扫描多反应监测模式下测定,外标法定量。结果表明,13种目标物在1.0～100.0 ng/mL的范围内线性关系良好,相关系数(r)均不低于0.9960。在5.0、20.0、50.0μg/kg添加水平下的回收率为65.4%～110.0%,相对标准偏差(n=5)为3.7%～9.8%,检出限(以信噪比大于3计)为0.02～0.30μg/kg,定量限(以信噪比大于10计)为0.07～0.98μg/kg。该方法稳定可靠,灵敏度高,适用于柑橘中13种磺酰脲类除草剂残留的同时检测。     

椰子种皮油提取物的抗氧化活性研究

测定椰子种皮油提取物中的总酚含量,对羟基自由基、DPPH（1,1-二苯基-2-三硝基苯肼）自由基、ABTS（2,2连氮-双-（3-乙基苯并噻咪唑-6-磺酸）自由基清除能力和总抗氧化能力等抗氧化活性指标。结果表明,椰子种皮油提取物中含有较高的总酚含量（68 mg/g）,提取物浓度为0.1 mg/mL时对羟基自由基的清除率为56.89％,对DPPH自由基的清除率为71.0％,对ABTS自由基的清除率为96.4％,表明椰子种皮油提取物具有很好的抗氧化活性。     

高效液相色谱柱后光化学反应-荧光检测茶叶中黄曲霉毒素B1

建立了高效液相色谱/光化学反应器/荧光检测器测定茶叶中黄曲霉毒素B1的方法。用乙腈水溶液(V∶V=86∶14)提取黄曲霉毒素B1,提取液经净化柱和黄曲霉毒素B1免疫亲和柱净化,高效液相色谱测定。在黄曲霉毒素B1标准溶液质量浓度为0.591~5.91μg/L时,峰面积与浓度呈现良好的线性关系,黄曲霉毒素B1的回收率为85.4%~98.9%(添加量分别为0.510μg/kg、7.090μg/kg和14.180μg/kg),相对标准偏差为0.2%~1.8%,方法检出限为0.1μg/kg。运用所建立方法对市售的8个茶样及加标样品中的黄曲霉毒素B1进行检测,结果显示该方法选择性强、灵敏度高,适合茶叶中黄曲霉毒素B1的测定。     

高效液相色谱柱后光化学反应-荧光检测茶叶中黄曲霉毒素B1

建立了高效液相色谱/光化学反应器/荧光检测器测定茶叶中黄曲霉毒素B1的方法。用乙腈水溶液(V∶V=86∶14)提取黄曲霉毒素B1,提取液经净化柱和黄曲霉毒素B1免疫亲和柱净化,高效液相色谱测定。在黄曲霉毒素B1标准溶液质量浓度为0.591~5.91μg/L时,峰面积与浓度呈现良好的线性关系,黄曲霉毒素B1的回收率为85.4%~98.9%(添加量分别为0.510μg/kg、7.090μg/kg和14.180μg/kg),相对标准偏差为0.2%~1.8%,方法检出限为0.1μg/kg。运用所建立方法对市售的8个茶样及加标样品中的黄曲霉毒素B1进行检测,结果显示该方法选择性强、灵敏度高,适合茶叶中黄曲霉毒素B1的测定。     

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.     

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.     

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.     

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.     

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.     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta. Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X¹ (also called RX_act).     

Cyanobacteria Secondary Metabolites as Biotechnological Ingredients in Natural Anti-Aging Cosmetics: Potential to Overcome Hyperpigmentation,Loss of Skin Density and UV Radiation-Deleterious Effects

The loss of density and elasticity, the appearance of wrinkles and hyperpigmentation are among the first noticeable signs of skin aging. Beyond UV radiation and oxidative stress, matrix metalloproteinases (MMPs) assume a preponderant role in the process, since their deregulation results in the degradation of most extracellular matrix components. In this survey, four cyanobacteria strains were explored for their capacity to produce secondary metabolites with biotechnological potential for use in anti-aging formulations. Leptolyngbya boryana LEGE 15486 and Cephalothrix lacustris LEGE 15493 from freshwater ecosystems, and Leptolyngbya cf. ectocarpi LEGE 11479 and Nodosilinea nodulosa LEGE 06104 from marine habitats were sequentially extracted with acetone and water, and extracts were analyzed for their toxicity in cell lines with key roles in the skin context (HaCAT, 3T3L1, and hCMEC). The non-toxic extracts were chemically characterized in terms of proteins, carotenoids, phenols, and chlorophyll a, and their anti-aging potential was explored through their ability to scavenge the physiological free radical superoxide anion radical (O₂^•−), to reduce the activity of the MMPs elastase and hyaluronidase, to inhibit tyrosinase and thus avoid melanin production, and to block UV-B radiation (sun protection factor, SPF). Leptolyngbya species stood out for anti-aging purposes: L. boryana LEGE 15486 presented a remarkable SPF of 19 (at 200 µg/mL), being among the best species regarding O₂^•− scavenging, (IC₅₀ = 99.50 µg/mL) and also being able to inhibit tyrosinase (IC₂₅ = 784 µg/mL), proving to be promising against UV-induced skin-aging; L. ectocarpi LEGE 11479 was more efficient in inhibiting MMPs (hyaluronidase, IC₅₀ = 863 µg/mL; elastase, IC₅₀ = 391 µg/mL), thus being the choice to retard dermal density loss. Principal component analysis (PCA) of the data allowed the grouping of extracts into three groups, according to their chemical composition; the correlation of carotenoids and chlorophyll a with MMPs activity (p < 0.01), O₂^•− scavenging with phenolic compounds (p < 0.01), and phycocyanin and allophycocyanin with SPF, pointing to these compounds in particular as responsible for UV-B blockage. This original survey explores, for the first time, the biotechnological potential of these cyanobacteria strains in the field of skin aging, demonstrating the promising, innovative, and multifactorial nature of these microorganisms.     

Marine Pharmacology in 2009–2011: Marine Compounds with Antibacterial,Antidiabetic, Antifungal,Anti-Inflammatory,Antiprotozoal, Antituberculosis,and Antiviral Activities; Affecting the Immune and Nervous Systems,and other Miscellaneous Mechanisms of Action ?

The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998–2008 reviews of this series. The pharmacology of structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009–2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories.