Uncertainties in the determination of pyrrolizidine alkaloid levels in naturally contaminated honeys and comparison of results obtained by different analytical approaches

The contamination of honey with hepatotoxic pyrrolizidine alkaloids (PAs) is a well-known hazard for food safety. While management strategies and controls of the honey industry aim to reduce the PA levels, uncertainties remain with regard to the safety of regionally produced and marketed honey. In addition, a previous study showed large differences of results obtained after various periods of storage and apparent differences between the analytical results of different laboratories. Therefore, this study aimed at examining these uncertainties by monitoring the impact of storage on the PA and PA N-oxide (PANO) content of two freshly harvested honeys and on possible demixing effects caused by pollen settling. Additionally, three analytical approaches – target analysis with matrix-matched calibration or standard addition and a sum parameter method – were applied for a comparative analysis of 20 honeys harvested in summer 2016. All samples originated from Schleswig-Holstein in Northern Germany where the PA plant Jacobaea vulgaris is currently observed on a massive scale. The results of the time series analyses showed that PANO levels markedly decreased within a few weeks and practically reached the LOD 16 weeks after harvest. Tertiary PAs, by contrast, remained stable and did not increase as a consequence of PANO decrease. The experiments on a putative demixing, which may result in a heterogeneous distribution of PAs/PANOs, revealed that there was no such effect during storage of up to 12 weeks. A comparison of the PA/PANO levels obtained by different analytical approaches showed that in some cases the sum parameter method yielded much higher levels than the target approaches, whereas in other cases, the target analysis with standard addition found higher levels than the other two methods. In summary, the results of this study highlight uncertainties regarding the validity and comparability of analytical results and consequently regarding health risk assessment.     

苯乳酸抑制链格孢霉作用靶位的分析

以从自然腐败的樱桃上分离的链格孢霉（Alternaria sp.）LD3.0086为指示菌，研究苯乳酸对链格孢霉的主要抑制作用靶位。应用分光光度法测定苯乳酸对链格孢霉的最小抑菌浓度，通过卡尔科弗卢尔荧光增白剂染液（calcofluor white，CFW）染色观察苯乳酸对菌丝顶端生长的破坏作用，利用扫描电子显微镜和透射电子显微镜观察链格孢霉的超微结构变化，通过测定苯乳酸作用前后链格孢霉上清液中N-乙酰葡萄糖胺质量浓度变化研究苯乳酸对菌丝细胞壁的破坏作用，应用荧光双染色法观察苯乳酸对链格孢霉菌丝细胞膜的损伤作用。结果表明，12.5 mmol/L的苯乳酸能有效抑制链格孢霉的生长；与对照组（无菌水处理）相比，苯乳酸处理后链格孢霉顶端生长细胞无明显形变，经12.5 mmol/L苯乳酸处理的链格孢霉上清液中N-乙酰葡萄糖胺质量浓度基本不变；苯乳酸处理24 h，链格孢霉菌丝细胞壁表面无明显损伤，细胞内结构发生明显变化；苯乳酸短时间（4 h）处理链格孢霉，菌丝细胞膜仍较为完整，加入苯乳酸较长时间（8 h）后细胞膜发生破裂。综合分析可知，苯乳酸对链格孢霉的主要作用靶位应不是菌丝体的细胞壁和细胞膜，而是在菌丝体内部，通过破坏菌丝内部细胞器结构或引起细胞内的生化反应，从而抑制链格孢霉的生长和繁殖，发挥抑菌活性。     

Natural occurrence of Fusarium toxins in peanut,sorghum and maize from Mysore (India)

Peanut, sorghum and maize samples were collected from the wholesale market in Mysore, India, over a period of one year (October 1984 to September 1985). The samples were analysed for the natural occurrence of T-2 toxin (T-2), diacetoxyscirpenol (DAS) and zearalenone by thin-layer chromatography, dermal toxicity test and gas chromatography. Of the total number of peanut samples analysed, 6.9% were positive for the toxic trichothecene(s) (T-2, up to 38.89 mg kg^?1; DAS, up to 2.03 mg kg^?1); 4.8% of total sorghum samples analysed contained T-2 up to 15 mg kg^?1. Zearalenone was not found in any of the samples tested, and no toxins were detected in any of the maize samples. Samples marketed during winter and summer periods were contaminated with the toxins. All the toxin-positive samples except one peanut sample were found in produce stored for more than a week.     

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。     

Toxicity of nitro compounds fromLotus pedunculatus to grass grub (Costelytra zealandica) (Coleoptera: Scarabaeidae)

Crude extracts of root of the forage legumesLotus pedunculatus andCoronilla varia (crownvetch) were toxic when administered orally to 3rd instarCostelytra zealandica larvae. A group of 3-nitropropanoyl-d-glucopyranoses was isolated from active fractions of the crude extracts. These toxins, some of which were already known fromC. varia, have not previously been reported fromL. pedunculatus. The compounds were present in root tissue of this species at a concentration of about 1% dry weight. They include the triester karakin and the diesters coronarian and cibarian, all of which were toxic to larvae ofC. zealandica at levels which could account fully for the activity of the crude extracts.     

心肌细胞电位传感器在海洋生物毒素检测中的研究

目前海洋毒素对人类健康的威胁越加严重,尤其是麻痹性毒素。提出了一种基于细胞电位传感器检测贝类的生物毒性的新方法,采用心肌细胞与微电子加工技术的微阵列芯片（MEA）相结合,构建了新型的心肌细胞电位传感器。通过心肌细胞与MEA芯片的紧密耦合,实现了实时监测心肌细胞电位的变化,输出稳定和一致性好的胞外场电位信号。通过检测海洋中危害较大的石房蛤麻痹性毒素（STX）,分析细胞的信号特征参数,实验结果表明,STX毒素对心肌细胞的电生理活动有明显的抑制作用,对脉冲幅值和脉冲频率有明显的浓度依赖性抑制作用。常规标准的生物毒性检测方法小鼠生物法的检出限为40 g/100 g,而心肌细胞电位传感器可检测的下限为1.004 ng/mL,检测范围为25 nmol/L~1600 nmol/L,通过对比表明该方法具有较好的检出限且检测方法相对简单,易于规范化和标准化。通过进一步的完善,该方法在海洋毒素的快速检测应用方面具有良好的发展前景。     

水环境中蓝藻毒素研究进展

随着社会的发展,水体富营养化日益严重,藻类及藻毒素严重污染了水环境,不仅给传统净水工艺带来不利影响,增加了水处理难度,而且严重威胁人类健康和生命安全,已成为全球性的环境问题.本文较详细地介绍了蓝藻的起源、特性及其危害,并综述了有关其检测方法及防治措施.最后,对蓝藻毒素降解技术的发展方向进行展望.     

去除藻毒素的水处理方法

蓝-绿藻水华及其所含毒素已成为我国许多富营养化水源的主要问题.蓝-绿藻所含的毒素是复杂的有机化合物,其中包括神经毒素、肝毒素和皮肤毒素.在水处理时如能有效去除藻类,则藻毒素将随之减少.除藻措施可在水源地或水厂内同时进行.在水源处可采取的措施是预氧化、投加除藻剂和防止水源水因水质或水温而引起的上下分层.一般水厂常规处理工艺不能有效去除藻毒素,可以采用强化混凝、优化粉末活性炭和臭氧以及氯的投加量、用生物活性炭过滤或组合工艺.其中生物预处理、臭氧氧化、粉末或颗粒活性炭吸附有较好去除效果.但是在藻类大量繁殖时,须慎重采用预氧化,否则当用氯或臭氧进行预氧化时,如投药量不当,会使藻细胞破裂,反而析出较多的毒素到水中.蓝-绿藻毒素的最佳去除工艺是臭氧和活性炭相结合的生物活性炭法.     

6-羧基壳聚糖凝胶珠及其吸附尿毒症低分子毒物研究

用NO2将壳聚糖6位羟甲基氧化成羧基,再以戊二醛作交联剂制备了具有较高强度的6羧基壳聚糖凝胶珠。SEM观察确认凝胶珠表面均匀分布许多“沟槽”。凝胶珠对尿毒症低分子毒物尿酸、马尿酸和肌酐的吸附量分别为2.61、1.5和0.81mg/g;几乎不吸附牛血清蛋白、尿素、肌酸。富含低分子毒物的血清经凝胶珠吸附后,其尿酸和马尿酸的含量可接近人体液正常值。     

Carvacrol and trans-Cinnamaldehyde Reduce Clostridium difficile Toxin Production and Cytotoxicity in Vitro

Clostridium difficile is a nosocomial pathogen that causes a serious toxin-mediated enteric disease in humans. Reducing C. difficile toxin production could significantly minimize its pathogenicity and improve disease outcomes in humans. This study investigated the efficacy of two, food-grade, plant-derived compounds, namely trans-cinnamaldehyde (TC) and carvacrol (CR) in reducing C. difficile toxin production and cytotoxicity in vitro. Three hypervirulent C. difficile isolates were grown with or without the sub-inhibitory concentrations of TC or CR, and the culture supernatant and the bacterial pellet were collected for total toxin quantitation, Vero cell cytotoxicity assay and RT-qPCR analysis of toxin-encoding genes. The effect of CR and TC on a codY mutant and wild type C. difficile was also investigated. Carvacrol and TC substantially reduced C. difficile toxin production and cytotoxicity on Vero cells. The plant compounds also significantly down-regulated toxin production genes. Carvacrol and TC did not inhibit toxin production in the codY mutant of C. difficile, suggesting a potential codY-mediated anti-toxigenic mechanism of the plant compounds. The antitoxigenic concentrations of CR and TC did not inhibit the growth of beneficial gut bacteria. Our results suggest that CR and TC could potentially be used to control C. difficile, and warrant future studies in vivo.