基于共有醛类中间体阻断及环外游离氨基加合终产物消除的食源性杂环胺双效减控途径研究

Heterocyclic amines (HAs) are hazardous substances generated by heat processing of food materials that rich in protein, and their carcinogenicity and mutagenicity could be attributed to the formation of DNA adduct through the exocyclic amino group. There are many kinds of HAs, and the same HAs could generate through different pathways. The present methods based on radical scavenging and phenylacetaldehyde trapping were just effective for blocking imidazoquino(xa)lines and PhIP formed by just one pathway of them, and the protein-bound states of HAs were also not considered, thus there are still high levels of HAs in the food systems. In order to reduce and control the HAs in food system, we plan to set targets of blocking the carbonyl of common aldehyde intermediates and eliminating the exocyclic amino group of HAs, and choose food material ingredients with bioactive amino and carboxyl groups (but not precursors of hazardous substances) such as proline, so as to block and eliminate the HAs of different chemical states in food systems by reaction of their amino group with carbonyl group of aldehydes as well as carboxyl group with exocyclic amino group of HAs. The isotope labeling method and multi-responses kinetics will be employed, to investigate the effects of processing parameters on HAs, their precursors, aldehyde intermediates, blocking and eliminating adducts, and the quantitative model of processing parameters-HAs-adducts, thus demonstrate the new pathway and mechanism of reducing and controlling HAs. The results of this project could provide technical basis for effective blocking the formation of HAs, and eliminating HAs that already exist in the food systems, thus effectively eliminate the potential hazard of food originated HAs.

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，可通过其环外游离氨基与DNA加合产生致癌致突变毒性。杂环胺种类众多，且同一杂环胺有多条生成途径。现有基于清除自由基和苯乙醛捕获的方法仅针对喹(喔)啉类和PhIP等单一生成途径的阻断，且未考虑与蛋白结合的存在状态，导致体系中仍存有大量杂环胺。为有效减控体系中的杂环胺，本项目拟以共有醛类中间体羰基阻断和终产物环外游离氨基消除为目标，采用具有活性氨基和羧基结构的脯氨酸等非危害物前体的食品原料组分，通过其氨基和羧基分别与醛类羰基和环外游离氨基加合，阻断和消除体系中不同状态的杂环胺；通过同位素示踪法及多响应动力学，研究不同加工条件对杂环胺及其前体、醛类中间体和加合物的影响规律；构建加工条件-杂环胺-加合物的量化关系模型，阐明减控杂环胺的新途径及机制。本研究成果可为有效阻断杂环胺的生成，并消除已经存在的杂环胺，从而有效去除其潜在危害提供技术支撑。

本项目拟通过分析杂环胺的生成途径和分子结构入手，采用食品组分中的非杂环胺前体氨基酸与各类杂环胺的共有醛类中间体反应以阻断其生成，同时采用这些氨基酸与体系中已经生成的杂环胺反应直接消除其生成，通过中间体阻断和终产物消除两种共有途径以期更加有效地减控食品体系中的杂环胺。通过分析不同种类杂环胺生成模拟体系中的醛酮类化合物，并考察醛-肌酸酐模拟体系中的杂环胺的生成规律，确认了苯甲醛和苯乙醛是吡啶类杂环胺，丙酮醛和乙二醛是喹(喔)啉类杂环胺的关键中间体。系统考察了脯氨酸、组氨酸、半胱氨酸、甲硫氨酸、精氨酸和亮氨酸等六种非危害物前体氨基酸及其组合对葡萄糖/肌酸酐/苯丙氨酸、葡萄糖/肌酸酐/甘氨酸、葡萄糖/肌酸(酐)、葡萄糖/肌酸(酐)/苯丙氨酸+色氨酸+苏氨酸等单类或多类杂环胺生成模拟体系，结果发现组氨酸-脯氨酸组合在1:3的质量比时对葡萄糖/肌酸酐/苯丙氨酸体系中的PhIP有最高的抑制率达96%，同时对苯乙醛有最高的清除率45%。半胱氨酸-脯氨酸的组合在4:1的质量比下对葡萄糖/肌酸酐/甘氨酸模拟体系中的MeIQx的抑制率最高达62%，同时对丙酮醛的清除率最高达71%，在1:4的质量比下则对乙二醛的清除率最高可达49%。添加1%的组氨酸、亮氨酸或甲硫氨酸几乎可抑制葡萄糖/肌酸(酐)/苯丙氨酸模拟体系中100%的PhIP，且它们均可以与PhIP反应，其中脯氨酸可直接消除最多达23%的PhIP。在葡萄糖/肌酸(酐)/苏氨酸模拟体系中，甲硫氨酸最多可直接消除44%的MeIQx，亮氨酸最多可直接消除16%的MeIQ。以上结果表明，一些非前体氨基酸不仅能通过与共有醛类中间体反应阻断杂环胺的生成，还能直接与杂环胺反应直接消除已经生成的危害物。在以上结果的基础上建立烤牛肉饼和西式熏煮香肠实际食品体系，发现1%的组氨酸和0.5%的亮氨酸分别能抑制牛肉饼中达44%和43%的总游离态杂环胺，1%的组氨酸对总结合态杂环胺的最高抑制率可达50%。在西式熏煮香肠体系中，1%的组氨酸+1%的亮氨酸+1%的脯氨酸组合抑制总游离态杂环胺的能力最强达46%，该组合对总蛋白结合态杂环胺的抑制效果也最强达34%。

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