葡萄籽提取物对烤羊肉中PhIP形成的抑制机理

2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) is one of the heterocyclic amines that occurs most frequently and in the greatest abundance in charbroiled mutton. Exposure to PhIP increases the risk of colon carcinogenesis in humans. Our previous studies have shown that PhIP was effectively inhibited by 0.5% grape seed extract (GSE) in charbroiled mutton. However, there is still not a clear-cut inhibitory mechanism of GSE on PhIP formation in charbroiled mutton. Based on the hypothesis that trapping of phenylacetaldehyde, a key PhIP intermediate, may thus lead to significant inhibition of PhIP formation in charbroiled mutton. Mechanistic study will be subsequently carried out to characterize the probable inhibitory mechanism involved by modern technologies of sample preparation and identification, such as nonionic polymeric adsorbent (Amberlite XAD) and LC-MS/MS. This included examination and identification of dominant inhibitors of PhIP formation from GSE. The effect of phytochemicals from GSE on the formation of phenylacetaldehyde and the identification of adducts formed from phytochemicals and phenylacetaldehyde will be subsequently carried out through chemical model systems. Finally, the relevance of the proposed mechanism of action to practical applications will be assessed through identification of these adducts in charbroiled mutton system. The results of this study will provide a scientific theoretical basis for the quality control of charbroiled mutton and the application of natural extracts.

2-氨基-1-甲基-6-苯基-咪唑并[4,5-b]吡啶（PhIP）是烤羊肉中含量较多的杂环胺，可诱发人类结肠癌。我们前期研究发现，羊肉烧烤前添加0.5%葡萄籽提取物（Grape seed extract, GSE）可显著降低烤羊肉中PhIP的形成量，但其具体抑制机理尚不清楚。基于GSE主要化学成分可能通过捕获羊肉烤制过程形成的苯乙醛从而抑制PhIP产生的假说。本项目拟运用Amberlite XAD等分离技术，以LC-MS/MS等现代分析手段，首先对GSE中抑制PhIP形成的主要化学成分进行分离鉴定；随后通过化学模拟体系分析GSE主要化学成分对苯乙醛的影响，经同位素标记技术探索GSE主要化学成分与苯乙醛的反应机制，并对反应加合物结构进行表征；最后通过鉴定烤羊肉中产生的加合物而验证该假说，并进一步揭示GSE对烤羊肉中PhIP形成的抑制机理，为烤羊肉的品质控制及天然提取物的应用提供科学理论依据。

2-氨基-1-甲基-6-苯基-咪唑并[4,5-b]吡啶（PhIP）是烤羊肉中含量较多的杂环胺，可诱发人类结肠癌。基于GSE主要化学成分可能通过捕获羊肉烤制过程形成的苯乙醛从而抑制PhIP产生的假说。本课题运用Amberlite XAD等分离技术，以LC-MS/MS等现代分析手段，首先对GSE中抑制PhIP形成的主要化学成分进行分离鉴定；随后通过化学模拟体系分析GSE主要化学成分对苯乙醛的影响，经同位素标记技术探索GSE主要化学成分与苯乙醛的反应机制，并对反应加合物结构进行表征；最后通过鉴定烤羊肉中产生的加合物而验证该假说，并进一步揭示GSE对烤羊肉中PhIP形成的抑制机理，为烤羊肉的品质控制及天然提取物的应用提供科学理论依据。研究表明，GSE中各种馏分对PhIP均有抑制作用，且其成分较为复杂，其中单体酚如儿茶素的含量较高，达73.50 mg/g；GC-MS分析可知模拟体系中儿茶素与苯丙氨酸的摩尓比为1：4时可抑制90%苯乙醛的生成。这进一步证明儿茶素对PhIP形成的抑制存在抗氧化独立机制；随后通过以PhIP前体物组成的系统模拟体系试验并经LC-MS分析发现，只有当体系中同时存在儿茶素与苯丙氨酸时才会出现儿茶素与苯丙氨酸总分子量相当的特征化合物；经同位素标记研究发现，这些特征化合物均含有来源于苯丙氨酸的碎片；直接将苯乙醛与儿茶素反应进一步证实儿茶素能与苯乙醛形成加合物，从而减少PhIP的形成；然而，烤羊肉体系中未能检测出儿茶素与苯乙醛反应加合物，因此，本研究对于GSE中主要化学成分可能通过捕获羊肉烤制过程形成的活性羰基类物质-苯乙醛而抑制PhIP的产生的假说未能证实。