Cross-linked chitosan polymers as generic adsorbents for simultaneous adsorption of multiple mycotoxins

The primary objective of this study was to synthesize three types of cross-linked chitosan polymers and further investigate their adsorption capability for multiple mycotoxins, including aflatoxin B₁ (AFB₁), ochratoxin A (OTA), zearalenone (ZEN), fumonisin B₁ (FB₁), deoxynivalenol (DON) and T-2 toxin (T2). Among these synthetic adsorbents, cross-linked chitosan-glutaraldehyde complex presented the highest adsorption capability for AFB₁ (73%), OTA (97%), ZEN (94%) and FB₁ (99%), but no obvious adsorption for DON and T2 (<30%). The effect of various incubation conditions (contact time, dosage and pH) was also studied. Subsequently, the experimental data were fitted to Langmuir, Freundlich and Hill models. The best fitting model to describe AFB₁ and FB₁ adsorption was Langmuir model (R² ≥ 0.99), with the theoretical maximum adsorption amounts of 5.67 mg/g for AFB₁ and 15.7 mg/g for FB₁. The Hill model was the best model for OTA and ZEN adsorption (R² > 0.98), with the predicted maximum adsorption amounts were 24.8 mg/g for OTA and 9.18 mg/g for ZEN. In addition, the adsorption capability of adsorbent for the simultaneous presence of multiple mycotoxins was also evaluated in buffer system and simulated gastrointestinal condition. The results indicated that the coexisted multiple mycotoxins didn't affected the adsorption capability of adsorbent, whereas the adsorption amounts of toxins were decreased by some gastrointestinal components. The findings of this research suggest that chitosan–glutaraldehyde complex has the potential to be applied as multitoxin adsorbent material for reducing the combined adverse effect of multiple mycotoxins on humans and animals.     

Addition of phytochemical-rich plant extracts mitigate the antimicrobial activity of essential oil/wine mixtures against Escherichia coli O157:H7 but not against Salmonella enterica

Marinades for preparing raw meats for cooking are frequently made of wine and herbs. We simulated several formulations of potential antimicrobial marinades with these components and other food compatible/food derived extracts. Red wine formulations containing essential oils from oregano or thyme, or their primary active components carvacrol and thymol, respectively, and a mixture of plant extract powders from phytochemical-rich apple skin, green tea, and olive, were evaluated for inhibitory activity against the foodborne pathogens Escherichia coli O157:H7 and Salmonella enterica. Red wine alone exhibited low activity, as did the plant extract suspended in the wine. Surprisingly, the high activity of oregano or thyme essential oils in red wine was reduced in E. coli, but not in Salmonella, by addition of the plant extract. This study shows that essential oils in red wine can be an effective antimicrobial in food, however the possibility exists that phytochemicals, added to the treatment solution or natively present in the food itself, could adversely impact the antimicrobial activity and should be addressed with future studies.     

Quantitative assessment of risk associated with dietary intake of mycotoxin ochratoxin A on the adult inhabitants in Shanghai city of P.R. China

Mycotoxin ochratoxin A (OTA) is considered to be a possible risk factor for adverse effects in humans. In the present study, quantitative assessment of risk associated with dietary intake of OTA was performed based on consumption habits of the representative adult inhabitants in Shanghai city of P. R. China. Firstly, a total of 400 food samples randomly collected from different locations of Shanghai were analyzed by the previously established isotope dilution LC–MS/MS method. Then, 265 participants of 70 males and 195 females as representative inhabitants were invited to answer the designed questionnaire about the quantity and frequency of foods including four major varieties of grapes, cereals, beans and dried fruits as well as their derived products. Finally, all data were simulated by the point evaluation and model evaluation for the risk assessment of OTA contamination. Results from the point evaluation indicated that mean value of daily intake (DI) of OTA was 1.147 ng/kg body weight/day, which was lower than all the reference standards. However, DI value (8.566 ng/kg body weight/day) in the high percentile (97.5th) was obviously higher than the PTDI (5 ng/kg body weight/day) proposed by Scientific Committee on Food. Among the different groups of foods, OTA in cereals and derived products made the largest contribution to the potential healthy risk. The mean DI value and 97.5th percentile were 1.093 and 7.962 ng/kg body weight/day, respectively, indicating that more than 90% of the risk was due to the contamination of OTA in cereals and derived products. On the other hand, similar results were obtained by the Monte Carlo assessment model. Thus, from the currently available data and analyzed results on the adult inhabitants, regarding OTA contamination issues on food safety administration of Shanghai, there was no significant attention which should be paid on food consumption in Shanghai, besides cereals and derived products with very little possibility as the risk factors.     

Pesticide residues in the spring cabbage (Brassica oleracea L. var. capitata) grown in open field

A method was established to evaluate multi-residual dynamics of the pesticides (chlorpyrifos, dimethoate, cyhalothrin, cypermethrin, fenvalerate, deltamethrin and chlorothalonil) in the spring cabbage, Brassica oleracea L. var. capitata. The results showed that the pesticide residues were closely related with the times and dosage of application, and the weather after spraying. The half-lives of the seven pesticides in the vegetable were 2.0, 1.6, 1.6, 2.3, 2.2, 1.5 and 1.8 days, respectively. If the cabbages were treated one time at normal dosage of pesticides, and all pesticides maximum residue limits (MRLs) were not exceeded according to the recommended pre-harvest interval. However, if the vegetables were treated four times at the maximal dosage with a five-day’s interval, the half-lifes of chlorpyrifos, cypermethrin and chlorothalonil in the vegetable were 2.9, 2.6 and 4.1 days, respectively, and the final residual amount of chlorothalonil exceeded its MRL on cabbage, but the final residual amounts of cypermethrin and chlorpyrifos were below its MRLs on the cabbage. Furthermore, in both one-time and four-time spraying treatments, the final degradation rates of pesticides residues were above 80%.     

高效液相色谱-串联质谱法测定樱桃番茄中四种季铵类农药

建立了4种季铵类农药(矮壮素、燕麦枯、敌草快和缩节胺)的高效液相色谱-串联质谱(LC-MS/MS)检测方法。样品用75%乙腈-水溶液提取,高速离心后取上清液过尼龙滤膜,用亲水柱分离,以含0.1%甲酸的水:乙腈=25:75(V:V)作为流动相,在正离子多反应监测(MRM)模式下进行测定。4种季铵类农药的线性范围为0.5～100ng/mL,线性相关系数在0.9982～0.9996范围内,方法检出限为0.005mg/kg,可以满足国际限量的要求。在0.04、0.08、0.16mg/kg添加浓度下,4种季铵类农药的回收率为91.4%～106.3%,相对标准偏差(RSD)小于15%。本方法可用于樱桃番茄样品中4种季铵类农药的测定。     

Novel monoclonal antibody-based sensitive enzyme-linked immunosorbent assay and rapid immunochromatographic strip for detecting aflatoxin M1 in milk

Monoclonal antibody (mAb) that is specific to AFM1 was generated from the hybridoma cell line, 10F3C10, which was obtained by the fusion of mouse NS1 myeloma cells with the spleen cells of mouse that had been immunized with AFM1-bovine serum albumin (BSA). The 10F3C10 mAb is belong to the immunoglobulin G1 isotype. Both competitive direct and indirect enzyme-linked immunosorbent assay (ELISA) was utilized to characterize the mAb for AFM1. The concentrations of AFM1, AFB1 and AFG1 that caused 50% inhibition (IC₅₀) of the binding of AFM1-horseradish peroxidase (AFM1-HRP) to the antibody were found to be 0.022, 0.310 and 2.12 ng/mL, respectively. The immunochromatographic strip (immunostrip) assay with mAb-gold nanoparticle conjugates as a detection marker exhibited a visual limit of detection of 0.1 ng/mL for AFM1 and the analysis took a total of 10 min. Closely examining 17 milk-based samples using cdELISA revealed that four were slightly contaminated with AFM1 at concentrations from 0.002 to 0.054 ng/mL. All milk samples were negative in the immunostrip test because the levels of contaminant were below the detection limit of the strip. Notably, the presented cdELISA and immunostrip methods are highly sensitive methods for detecting AFM1 in milk.     

代谢组学法评价紫苏子抗小鼠急性肝损伤的作用

用代谢组学法对紫苏子抗小鼠急性肝损伤作用进行评价。研究构建四氯化碳（CCl4）致小鼠急性肝损伤模型,采用流动注射-三重四极杆-飞行时间质谱联用系统对模型组、紫苏子给药组、阳性药联苯双酯给药组及正常对照组动物的肝组织及全血代谢轮廓谱进行比较。采用主成分分析法对各组数据进行分析并初步筛选潜在生物标志物。代谢组学分析、血生化指标检测及病理研究表明,20 g/kg生药当量的紫苏子醇提物对CCl4致小鼠急性肝损伤模型具有与联苯双酯临床等效剂量相似的保肝作用。结果表明,柠檬酸、磷脂酸、溶血磷脂酰胆碱、溶血磷脂酰乙醇胺等9 个代谢物为CCl4致小鼠急性肝损伤及紫苏子保肝作用的潜在生物标志物;作用途径与脂质过氧化、能量代谢等有关。     

An immunoassay for ochratoxin A without the mycotoxin

Phage display peptide libraries allow the selection of new molecules capable of mimicking the structural and functional features of native proteins or chemicals. This technology can be applied to developing new reagents, which may serve as the surrogate of the original objects. In order to screen peptides capable of mimicking ochratoxin A (OTA) in the interaction with anti-OTA monoclonal antibody (McAb) and establish the immunoassay for OTA, an anti-OTA McAb was used as the target for panning-elution selection from a phage random seven-peptide library. After four rounds of panning, 11 phages were found to be able to mimic OTA in binding with the antibody. Enzyme-linked Immunosorbent Assay (ELISA) for detecting OTA was established with the phages. In the most sensitive assay, the linear range of the inhibition curve was 200–8000 pg/ml; the detection limit was 150 pg/ml. The inserted peptide sequences were deduced by DNA sequencing. The common amino acid residue sequence was IR(V)PMV(L)XX (X is any amino acid residues), which was verified by two synthesized peptides. The results demonstrated that those phage peptides could be used as the surrogate of OTA to establish the immunoassay.