固相萃取-超高效液相色谱-串联质谱法测定蜂蜜中39 种植物源性毒素

为有效评估蜂蜜中可能残留多种植物源性毒素的食品安全风险;建立和验证固相萃取-超高效液相色谱-串联质谱测定蜂蜜中39 种植物源性毒素的检测方法。试样经0.1%甲酸水提取;HLB小柱净化;多反应监测模式检测;基质匹配外标法定量。本方法中39 种植物源性毒素在各自浓度范围内线性关系良好;平均回收率介于78.7%～112.8%;相对标准偏差介于1.6%～15.2%（n＝6）。该方法具有操作简单、检测通量大、灵敏度高等特点;能够满足蜂蜜中该类毒素监测的应用需求。在实际36 批次样品的检测过程中;部分样品分别检出了不同含量的吡咯里西啶生物碱和闹羊花毒素III;证明蜂蜜中确具有残留该类植物毒素的风险。     

基于风险分析方法的食品中天然毒素污染防控

对食品中毒素污染进行风险分析具有重要的公共卫生意义. 天然毒素不仅可以污染食品引起食物中毒,而且还具有致癌、致畸、致突变作用. 本文在分析食品中天然毒素及危害的基础上,运用风险分析方法对其进行评估,以期为食品中的天然毒素污染防控提出建议.     

Structure–Activity Relationship Study of Spider Polyamine Toxins as Inhibitors of Ionotropic Glutamate Receptors

The spider polyamine toxins Joro spider toxin‐3 (JSTX‐3) and Nephila polyamine toxins‐1 and ‐8 (NPTX‐1 and NPTX‐8) are isolated from the venom of the orb‐weaver spider Nephila clavata (Joro spider). They share a high degree of structural resemblance, their aromatic head groups being the only difference, and were recently found to be very potent open‐channel blockers of ionotropic glutamate (iGlu) receptors. In this study we designed and synthesized a collection of 24 analogues of these toxins using a recently developed solid‐phase synthetic methodology. Systematic variation in two regions of the toxins and subsequent evaluation of biological activity at AMPA and NMDA subtypes of iGlu receptors provided succinct information on structure–activity relationships. In particular, one set of analogues were found to display exquisite selectivity and potency for AMPA receptors relative to the natural products. Thus, this systematic SAR study has provided new pharmacological tools for studies of iGlu receptors.     

Photobleaching Reveals Heterogeneous Stoichiometry for Equinatoxin II Oligomers

Equinatoxin II (EqtII), a sea anemone cytolysin, is known to oligomerize to form pores that spontaneously insert into membranes. Crystallographic and cryo‐EM studies of structurally similar cytolysins offer contradictory evidence for pore stoichiometry. Here we used single‐molecule photobleaching of fluorescently labeled EqtII to determine the stoichiometry of EqtII oligomers in supported lipid bilayers. A frequency analysis of photobleaching steps revealed a log‐normal distribution of stoichiometries with a mean of 3.4±2.3 standard deviations. Comparison of our experimental data with simulations of fixed stoichiometries supports our observation of a heterogeneous distribution of EqtII oligomerization. These data are consistent with a model of EqtII stoichiometry where pores are on average tetrameric, but with large variation in the number of subunits in individual pores.     

百菌清及其三氟衍生物对番茄早疫病菌的室内抑菌活性比较

采用生长速率法测定了不同浓度的百菌清及其三氟衍生物对番茄早疫病菌Alternaria solani(Ell,et Mart.)Jones es Gmut的室内杀菌毒力。试验结果表明,百菌清及其三氟衍生物的ED50值分别为6089．89mg／L和156．43mg/L。,前者是后者的38．93倍。百菌清三氟衍生物的毒力明显高于百菌清。     

几种杀菌剂对芦荟黑斑病菌室内活性测定

通过供试的7种药剂对芦荟黑斑病菌体外抑制作用测试结果表明,所有药剂对其孢子萌发都有不同程度的抑制作用,其中异菌脲、咪鲜胺、嘧霉胺的抑制效果要优于氟硅唑、代森锰锌、百菌清、苯醚甲环唑;7种药剂对芦荟黑斑病菌菌丝体的抑制作用测定结果显示,所有药剂对菌丝生长都有显著的抑制作用,其中咪鲜胺锰络合物可湿性粉剂对菌丝体抑制效果最好,抑菌率达84.24%;异菌脲、氟硅唑、苯醚甲环唑次之。     

肉桂醛对链格孢菌生长及非寄主选择性毒素合成的影响

目的 初步探究肉桂醛对葡萄采后链格孢菌菌丝体生长及非寄主选择性毒素合成的影响。方法 采用扫描电镜(scanning electron microscopy, SEM)观察肉桂醛处理后链格孢菌菌丝体的形态结构; 测定处理后菌丝体脂质和麦角固醇含量, 胞外电导率、OD260值和菌丝体荧光强度; 高效液相色谱(high performance liquid chromatography, HPLC)测定处理后链格孢酚(alternariol, AOH)、交链格孢酚单甲醚(alternariol monomethyl ether, AME)含量的变化。结果 扫描电镜结果显示肉桂醛处理后链格孢菌菌丝体形态结构明显被破坏; 脂质和麦角固醇含量显著下降; 胞外电导率和OD260值以及菌丝体荧光强度显著增加; AOH、AME的含量显著下降。 结论 肉桂醛通过破坏细胞膜通透性和完整性来抑制链格孢菌菌丝体生长, 同时体内主要非寄主选择性毒素合成受到抑制。     

超高效液相色谱-串联质谱法同时测定小麦制品中4种交链孢霉毒素

目的建立测定4种小麦制品(挂面、馒头、面包和饼干)中4种交链孢霉毒素的超高效液相色谱-串联质谱法。方法 4种小麦制品加入NaCl后,经酸化乙腈提取,固相萃取柱(SPE)净化后,以HSS T3色谱柱(2.1 mm×100 mm,1.7μm)为分析柱,以0.15 mmol/L碳酸氢铵水溶液-甲醇为流动相进行梯度洗脱,以负离子电喷雾模式电离(ESI~-),多反应离子监测(MRM)方式进行定性及定量检测,外标法定量。结果在0.040～50μg/L的线性范围内,4种交链孢霉毒素的回归方程均呈良好的线性关系,相关系数(r)0.99。交链孢菌酮酸、交链孢酚、腾毒素和交链孢酚单甲醚的方法检出限分别为0.10、0.01、0.03和0.01μg/kg,3个加标水平的回收率为85.7%～102%,相对标准偏差(RSD)为0.8%～11.0%。应用该方法对流通环节的挂面、馒头、面包和饼干进行检测,4种交链孢霉毒素均有检出,其浓度为0.02～185.00μg/kg。结论该方法灵敏度高、简便,适用于小麦制品中多种交链孢霉毒素的同时测定。