杂环胺人工抗原的合成以及多克隆抗体的制备

为建立适用于一类杂环胺的酶联免疫吸附检测方法(enzyme-linked immunosorbent assay,ELISA),利用改良的碳化二亚胺法将在2-氨基-3,4,8-三甲基咪唑[4,5-f]-喹喔啉(2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline,4,8-DiMeIQx)的2-氨基处连接丁二酸单甲酯酰氯制备的半抗原偶联蛋白获得人工抗原。该方法利用适当pH值的缓冲体系,将酯的水解和蛋白偶合一步完成,与传统方法相比,有效地节省了反应时间和成本,且对人工抗原的紫外扫描验证和多克隆抗体效价检测结果都直接和间接地表明偶合是成功的。最终免疫获得4,8-DiMeIQx结构类似物的多克隆抗体,该抗体的最高效价为1∶450 000,且经直接竞争ELISA检测,该抗体对目标物4,8-DiMeIQx的灵敏度(IC50)为24.0μg/L,最低检测限(IC15)为1.8μg/L,对其结构类似物7,8-DiMeIQx、8-Me IQx、2-氨基-3-甲基咪唑[4,5-f]-喹喔啉(IQx)、2-氨基-3,4,7,8-四甲基咪唑[4,5-f]-喹喔啉(Tri Me IQx)的灵敏度分别为35.0、30.0、28.0、40.0μg/L,而其他与目标物结构相差较大的杂环胺,像2-氨基-1-甲基-6-苯基咪唑[4,5-b]吡啶(Ph IP)、2-氨基-3-甲基咪唑[4,5-f]喹啉(IQ)和2-氨基-3,4-二氨基咪唑[4,5-f]喹啉(2-amino-3,4-dimethyl-imidazo[4,5-f]quinoline,Me IQ),它们几乎不与抗体结合(CR0.01%)。由此可见,可以利用该抗体建立高效快速的杂环胺ELISA检测方法用以定量或定性检测肉类加工食品中的一类杂环胺。     

葡萄籽提取物对烤羊肉中杂环胺形成的影响

将0.05%VE,0.1%与0.5%葡萄籽提取物,0.1%与0.5%槲皮素分别添加于羊肉表面,在200℃下煎烤10 min,利用固相萃取-配备二极管阵列检测器和荧光检测器的高效液相色谱分析烤羊肉中15种杂环胺的形成量,以探讨天然提取物对烤羊肉中杂环胺形成量的影响。结果表明:烤羊肉中共检测出10种杂环胺,其中极性杂环胺4种,非极性杂环胺6种,总量达51.68 ng/g。在极性杂环胺中2-氨基-1-甲基-6-苯基-咪唑并[4,5-b]吡啶(PhIP)的形成量较高,达10.50 ng/g;非极性杂环胺中9H-吡啶并[3,4-b]吲哚(Norharman)与1-甲基-9H-吡啶并[3,4-b]吲哚(Harman)的形成量较高,分别达19.66 ng/g与12.23 ng/g。烤羊肉中添加天然抗氧化剂只对极性杂环胺有抑制作用,其中添加0.5%葡萄籽提取物可以显著抑制2-氨基-3甲基咪唑并[4,5-f]喹啉(IQ),2-氨基-3,8-二甲基咪唑并[4,5-f]喹喔啉(MeIQx),2-氨基-3,4,8-三甲基咪唑并[4,5-f]喹喔啉(4,8-DiMeIQx)与PhIP 4种极性杂环胺的形成(P<0.05),其生成量分别减少36.65%,67.73%,35.63%与30%。天然抗氧化剂对烤羊肉中非极性杂环胺的抑制作用不明显。     

热加工食品中杂环胺形成及抑制机制

杂环胺是富含蛋白质的食品原料在热加工过程中产生的危害物,种类众多,且同一杂环胺有多条生成途径。本文主要综述了杂环胺的形成途径以及抑制机制,喹啉类和喹喔啉类可通过肌酸酐、葡萄糖和氨基酸的美拉德反应途径以及自由基途径形成;吡啶类(2-氨基-1甲基-6苯基-咪唑并[4,5-b]吡啶)可由苯丙氨酸的热解产物苯乙醛与肌酸酐经过一系列复杂的反应生成;氨基咔啉类主要是蛋白或氨基酸在250℃以上发生降解和热分解生成。添加酚类抗氧化剂、香辛料提取物、大蒜、洋葱、维生素等组分,可以清除自由基、捕获苯乙醛、抑制美拉德反应等机制对喹(喔)啉类和吡啶类(2-氨基-1甲基-6苯基-咪唑并[4,5-b]吡啶)等生成进行抑制。为有效阻断杂环胺的生成,去除其潜在危害提供理论支撑。     

陈皮对烘烤牛肉干中杂环胺含量的影响

探讨陈皮对烘烤牛肉干中杂环胺生成及牛肉干质量损失率、色差、感官指标的影响.陈皮的总酚物质含量及抗氧化能力分别通过福林-酚法及DPPH法测定,牛肉干中杂环胺含量利用高压液相色谱法测定.在没有经过陈皮水提物腌制处理牛肉干中检测出2-氨基-3,8-二甲基咪唑并[4,5-F]喹喔啉(MeIQx)、2-氨基-3,4,8-三甲基咪唑并[4,5-用喹喔啉(4,8DiMeIQx)、9H-吡啶并[3,4-B]吲哚(Norharman)、1-甲基-9H-吡啶并[3,4-B]吲哚(Harman)和2-氨基-1-甲基-6-苯基-咪唑并[4,5-B]吡啶(PhIP),总含量为44.01ng/g.160mg/mL的陈皮水提物可显著降低MeIQx(34.3％),PhIP(96.5％),但是显著增加了Norharman(32.4％);且陈皮提取液浓度越高、腌制时间越长,其对牛肉干中杂环胺含量的影响越大;陈皮腌制处理对牛肉干质量损失率没有显著影响,而色泽随着陈皮浓度的升高而明显变淡;感官评价表明经过陈皮腌制的牛肉干在颜色及风味感官品质上无不良影响.因此,陈皮提取物腌制是一种较好的抑制烘烤牛肉干中杂环胺的方法.     

不同添加量的大豆分离蛋白和淀粉对烤猪肉中杂环胺形成的影响

分别将2.5%、5.0%、7.5%和10.0%的大豆分离蛋白(SPI)和淀粉添加于猪肉中,采用UHPLC-MS/MS法测定其中16种杂环胺的含量,探讨其对杂环胺形成的影响。结果表明:添加2.5%的SPI和淀粉后,除喹喔啉类(Me IQx和4,8-Di Me IQx)外,各杂环胺的含量均显著增加(p0.05)。随着添加量的增加,杂环胺的含量先升高后开始下降。当添加量达到10.0%时,SPI的添加对4,8-Di Me IQx的形成出现显著抑制作用(p0.05),而淀粉的添加对吡啶和喹啉/喹喔啉杂环胺的促进作用则变得不再显著(p0.05)。由此可见,SPI和淀粉的添加对烤猪肉体系中多数杂环胺的形成具有低剂量促进,且随着剂量的增多促进效果逐渐减弱的影响规律。     

胶体金免疫层析法检测禽蛋中氯羟吡啶残留

目的 建立胶体金免疫层析法检测禽蛋中氯羟吡啶残留的分析方法。方法 在用间接竞争酶联免疫吸附法分析氯羟吡啶单克隆抗体灵敏度和交叉反应性的基础上,以胶体金标记单克隆抗体作为示踪标志物,以包被氯羟吡啶半抗原-卵清蛋白偶联物和羊抗鼠IgG的硝酸纤维素膜作为载体,制备了氯羟吡啶胶体金免疫层析试纸条。结果 氯羟吡啶单克隆抗体的半抑制浓度(half maximal inhibitory concentration,IC₅₀)为1.6μg/L,与地克珠利、二硝托胺、尼卡巴嗪、磺胺喹噁啉、磺胺二甲嘧啶、癸氧喹酯、盐酸氨丙啉和盐酸氯苯胍8种药物均无交叉反应。制备的胶体金免疫层析试纸条肉眼判定禽蛋中氯羟吡啶的检出限为15μg/kg,灵敏度为98%、特异性为93%、假阴性率为2%、假阳性率为7%。结论 制备的试纸条具有操作简单、检测快速、成本低等优点,可用于大批量禽蛋样本中氯羟吡啶残留的初步筛选。     

氨基甲酸酯类农药半抗原的设计与改造

本研究设计了一种针对氨基甲酸酯类农药半抗原的通用改造,制备了涕灭威和异丙威两种人工半抗原。通过分子模拟手段和制备鼠源多克隆抗体对半抗原改造效果进行评价。结果表明,最终涕灭威抗体效价为5.84×105,对涕灭威的IC₅₀为0.225 μg/mL,对涕灭威半抗原的交叉反应率为107.14%;异丙威抗体效价为4.1×105,对异丙威的IC₅₀为0.4 μg/mL,对异丙威半抗原的交叉反应率为105.26%。经该通用改造后的半抗原可以代替目标药物用于免疫分析方法的建立。     

温和条件下模型体系中烧烤风味及杂环胺形成测定

以美拉德模型体系葡萄糖-肌酸酐-氨基酸（丙氨酸、苏氨酸、甘氨酸）为研究对象,探索3 个体系在130 ℃条件下反应3 h后风味物质及杂环胺的形成。采用固相微萃取-气相色谱-质谱联用方法检测表明,3 种模型均产生烧烤风味物质,主要为烷基吡嗪类。高效液相色谱分析表明,丙氨酸模型（Ⅰ）和甘氨酸模型（Ⅲ）均检测到2-氨基-3,4-二甲基咪唑并[4,5-f]喹啉、2-氨基-3,4,8-三甲基咪唑并[4,5-f]喹喔啉和2-氨基-3,7,8-三甲基咪唑并[4,5-f]喹喔啉3 种杂环胺,苏氨酸模型（Ⅱ）检测到了2-氨基-3,4-二甲基咪唑并[4,5-f]喹啉和2-氨基-3,4,8-三甲基咪唑并[4,5-f]喹喔啉2 种杂环胺;3 种模型体系均未检测到2-氨基-3-甲基咪唑并[4,5-f]喹啉和2-氨基-3,8-二甲基咪唑并[4,5-f]喹喔啉。130 ℃温和条件下,1.5 h内各模型体系中杂环胺的生成量很少,1.5 h后杂环胺总量随着加热时间的延长逐渐增多,3 h时模型Ⅰ、Ⅱ、Ⅲ中杂环胺总量分别为（375.50±15.80）、（414.00±18.40）、（363.50±12.20） ng/mL。本研究为肉制品加工尤其是烤肉制品加工如何控制加工条件,从而实现美拉德反应定向控制、减少杂环胺的产生提供一定参考。     

熟肉制品中杂环胺的形成与抑制研究进展

杂环胺是熟肉制品中最常见的危害物,其种类繁多,形成途径复杂,抑制机制也不尽相同。本文介绍了2 类杂环胺的结构,主要阐述喹啉和喹喔啉类、2-氨基-1-甲基-6-苯基咪唑[4,5-b]吡啶、β-咔啉类（1-甲基-9H-吡啶[4,3-b]吲哚（1-methyl-9H-pyrido[4,3-b]indole,harman）、9H-吡啶[4,3-b]吲哚（9H-pyrido[4,3-b]indole,norharman））以及结合态杂环胺的形成途径,归纳减少杂环胺形成的措施及机理（控制加工条件和前体物、添加外源物质清除自由基和中间体、抑制美拉德反应等）,并对目前的研究现状进行概括。     

固相萃取-液相色谱-串联质谱法测定市售卤肉制品中5种杂环胺含量

建立了LC-MS/MS快速检测卤肉制品中MeIQ、MeIQx、4,8-DiMeIQx、7,8-DiMeIQx和PhIP 5种杂环胺的方法。样品经40 g/L NaOH-甲醇溶液超声提取,用聚苯乙烯二乙烯苯固相萃取小柱(Poly-Sery PSD)净化,在电喷雾离子源正离子(ESI+)多反应监测(MRM)模式下进行测定。5种杂环胺化合物在0.1~10 μg/L范围内线性关系良好,决定系数R2在0.9976~0.9997之间,在空白样品中的平均添加回收率为76.9%~127.7%,日内相对标准偏差(RSD)为1.0%~9.5%,日间相对标准偏差(RSD)为2.1%~8.7%。在信噪比(S/N)分别为3和10时各化合物的LODs在0.01~0.1 μg/kg,LOQs在0.025~0.25 μg/kg。该方法分析时间短,准确度高,精密度好,可满足卤肉中多种杂环胺同时检测的要求。     

Heterocyclic aromatic amines in fried poultry meat

 Heterocyclic aromatic amines are mutagenic compounds that are formed during heating of meat and fish. These substances are products of the reaction of creatine with amino acids and carbohydrates. It is recommended that exposure to these probable human carcinogens should be minimised. In fried boneless lean turkey breast meat five heterocyclic aromatic amines {2-amino-1-methyl-imidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimethyl-imidazo-[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethyl-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)} were found. The temperature regime which was applied for frying resulted in a surface temperature of about 140°C. Clean-up was done by acid-base partition followed by solid-phase extraction (SPE) using blue cotton. HPLC analysis was carried out using electrochemical detection for IQ- and IQx-type compounds and fluorescence detection for PhIP. The low temperatures used during frying yielded comparably lower amounts of heterocyclic aromatic amines. The concentrations of the aromatic amines were as follows: IQ 1.1 μg/kg, MeIQ 0.9 μg/kg, MeIQx μg/kg, 4,8-DiMeIQx 0.4 μg/kg, and PhIP 3.8 μg/kg. Received: 19 February 1997 / Revised version: 21 April 1997     

Dietary exposure to heterocyclic amines in high-temperature cooked meat and fish in Malaysia

The intake of heterocyclic amines is influenced by the amount and type of meat and fish ingested, frequency of consumption, cooking methods, cooking temperature, and duration of cooking. In this study, the dietary intake of heterocyclic amines in Malaysia and their main sources were investigated. Forty-two samples of meat and fish were analysed by high-performance liquid chromatography with photodiode array detector to determine the concentration of the six predominant heterocyclic amines, namely: 2-amino-3-methylimidazo[4,5-f] quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f] quinoline(MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f] quinoxaline (4,8-DiMeIQx), 2-amino-3,7,8-trimethylimidazo[4,5-f] quinoxaline (7,8-DiMeIQx), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Dietary intake data were obtained using a food-frequency questionnaire when interviewing 600 Malaysian respondents. The level of total heterocyclic amines in food samples studies ranged from not detected to 38.7 ng g^?1. The average daily intake level of heterocyclic amine was 553.7 ng per capita day^?1. The intake of PhIP was the highest, followed by MeIQx and MeIQ. The results reveal that fried and grilled chicken were the major dietary source of heterocyclic amines in Malaysia. However, the heterocyclic amine intake by the Malaysian population was lower than those reported from other regions.     

Antioxidant spices reduce the formation of heterocyclic amines in fried meat

 Heterocyclic aromatic amines (HAs) are mutagenic compounds that are formed during heating of meat and fish. These substances are reaction products of creatine with amino acids and carbohydrates. It is recommended that exposure to these probable human carcinogens should be minimised. Five heterocyclic aromatic amines which occur in beef were investigated: 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethyl-imidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethyl-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx), and 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP). Clean-up was done by acid-base partition followed by SPE using blue cotton. HPLC analysis was carried out by using electrochemical detection for IQ- and IQx-type compounds and fluorescence detection for PhIP. The concentrations of the aromatic amines were as follows: IQ, 10.2 μg/kg; MeIQ, 2.46 μg/kg; MeIQx, 13.2 μg/kg; 4,8-DiMeIQx, 2.26 μg/kg; and PhIP, 5.48 μg/kg. The application of spices (rosemary, thyme sage, garlic, brine) reduced the content of the HAs below 60% of the amount found in the control. Received: 23 April 1998     

Tandem solid phase extraction coupled to LC–ESI–MS/MS for the accurate simultaneous determination of five heterocyclic aromatic amines in processed meat products

Carcinogenic heterocyclic aromatic amines are difficult to measure since only trace levels are present in processed meat products. In this study, typical heterocyclic aromatic amines, including 2-amino-3-methylimidazo [4,5-f] quinoline (IQ), 2-amino-3,4-dimethylimidazo [4,5-f] quinoline (MeIQ), 2-amino-3,8-dimethyli-midazo [4,5-f] quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimi-dazo [4,5-f] quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-ph-enylimidazo [4,5-b]pyridine (PhIP), were studied to develop a sensitive and accurate method for their rapid quantification in animal-derived products, with 2-Amino-3,4,7,8-dimethylimidazo [4,5-f] quinoxalline (TriMeIQx) as an internal standard. Liquid chromatography–electrospray-tandem mass spectrometry conditions were analyzed to enhance detection sensitivity. Diatomaceous earth was employed to extract heterocyclic aromatic amines from meat samples, and the analytes were purified and enriched using tandem solid phase extraction, with siliprep propylsulfonic acid coupled to a C₁₈ cartridge. A number of parameters, including pH, eluent and volume, were carefully optimized to improve the extraction and purification efficiency. Under the optimal experimental conditions, the limits of detection for each analyte within the meat matrix were 0.5 pg (injected). The established method was applied to evaluate commercial meat products. At three spiked levels of 0.2, 1 and 4 μg kg⁻¹, the recoveries and relative standard deviations were measured as 76.4–122.2 and 0.9–23.4%, respectively, suggesting the developed method is promising for the accurate quantification of heterocyclic aromatic amines at trace levels in processed meats.     

Inhibitory effects of pomegranate seed extract on the formation of heterocyclic aromatic amines in beef and chicken meatballs after cooking by four different methods

Beef and chicken meatballs with a 0.5% (w/w) pomegranate seed extract were cooked using four different cooking methods (oven roasting, pan cooking, charcoal-barbecue, and deep-fat frying) and six heterocyclic aromatic amines; IQ, MeIQx, 4,8-DiMeIQx, PhIP, norharman, and harman were observed. In the beef meatballs, the highest inhibitory effects of pomegranate seed extract on heterocyclic aromatic amines formation were 68% for PhIP, 24% for norharman, 18% for harman, 45% for IQ, and 57% for MeIQx. Total heterocyclic aromatic amine formation was reduced by 39% and 46% in beef meatballs cooked by charcoal-barbecue and deep-fat frying, respectively. In the chicken meatballs, the highest inhibitory effects were 75% for PhIP, 57% for norharman, 28% for harman, 46% for IQ, and 49% for MeIQx. When the pomegranate seed extract was added to the chicken meatballs cooked by deep-fat frying, the total heterocyclic aromatic amine formation was inhibited by 49%, in contrast the total heterocyclic aromatic amine contents after oven roasting increased by 70%.     

Determination of Heterocyclic Aromatic Amines in Cooked Commercial Frozen Meat Products by Ultrafast Liquid Chromatography

This paper describes a method for the determination of nine heterocyclic aromatic amines (HCAs) in commercial frozen meat products, which were sold in Turkey by ultrafast liquid chromatography (UFLC) with ultraviolet visible detection. HCAs are separated on a Shim-pack XR-ODS (7.5?×?3 mm, 2.2 μm). Varying levels of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) (up to 1.95 ng/g), 2-amino-3-methylimidazo[4,5-f]quinoxaline (IQx) (up to 4.17 ng/g), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) (up to 0.69 ng/g), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) (up to 0.83 ng/g), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) (up to 0.22 ng/g), 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx) (up to 0.94 ng/g), 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) (up to 4.58 ng/g), 2-amino-9H-pyrido[2,3-b]indole (AαC) (up to 0.57 ng/g), and 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC) (up to 3.51 ng/g) were detected in these commercial frozen meat products of Turkey. The data obtained show clearly that HCAs could be isolated in a very short time (5 min) by using UFLC.     

Kinetics of Formation of Polar Heterocyclic Amines in a Meat Model System

A model system was used to examine kinetics of formation of polar heterocyclic amines by heating the precursors creatinine, glucose and amino acids in proportions similar to those in bovine meat but at higher concentrations. Formation of heterocyclic amines was studied between 150 and 225°C for 0.5–120 min, depending on temperature. Heated samples were subjected to solid phase extraction and HPLC analysis, with photodiode array detection for identification and quantification of heterocyclic amines. IQx, MeIQx, 7,8-DiMeIQx, 4,8-DiMeIQx, PhIP, harman and norharman were identified. A first-order reaction model and the Eyring equation were fitted to the formation of polar heterocyclic amines to obtain rate constants and their temperature dependence.