Kim Jae Kyeom, Gallaher Daniel D, Chen Chi, Yao Dan, Trudo Sabrina P
Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN.
Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN
J Nutr. 2015 Mar;145(3):442-51. doi: 10.3945/jn.114.202622. Epub 2014 Dec 24.
Heterocyclic aromatic amines, such as 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), are carcinogenic compounds produced during heating of protein-containing foods. Apiaceous vegetables inhibit PhIP-activating enzymes, whereas cruciferous vegetables induce both PhIP-activating and -detoxifying enzymes.
We investigated the effects of these vegetables, either alone or combined, on PhIP metabolism and colonic DNA adduct formation in rats.
Male Wistar rats were fed cruciferous vegetables (21%, wt:wt), apiaceous vegetables (21%, wt:wt), or a combination of both vegetables (10.5% wt:wt of each). Negative and positive control groups were fed an AIN-93G diet. After 6 d, all groups received an intraperitoneal injection of PhIP (10 mg · kg body weight(-1)) except for the negative control group, which received only vehicle. Urine was collected for 24 h after the injection for LC-tandem mass spectrometry metabolomic analyses. On day 7, rats were killed and tissues processed.
Compared with the positive control, cruciferous vegetables increased the activity of hepatic PhIP-activating enzymes [39.5% and 45.1% for cytochrome P450 (CYP) 1A1 (P = 0.0006) and CYP1A2 (P < 0.0001), respectively] and of uridine 5'-diphospho-glucuronosyltransferase 1A (PhIP-detoxifying) by 24.5% (P = 0.0267). Apiaceous vegetables did not inhibit PhIP-activating enzymes, yet reduced colonic PhIP-DNA adducts by 20.4% (P = 0.0496). Metabolomic analyses indicated that apiaceous vegetables increased the relative abundance of urinary methylated PhIP metabolites. The sum of these methylated metabolites inversely correlated with colonic PhIP-DNA adducts (r = -0.43, P = 0.01). We detected a novel methylated urinary PhIP metabolite and demonstrated that methylated metabolites are produced in the human liver S9 fraction.
Apiaceous vegetables did not inhibit the activity of PhIP-activating enzymes in rats, suggesting that the reduction in PhIP-DNA adducts may involve other pathways. Further investigation of the importance of PhIP methylation in carcinogen metabolism is warranted, given the inverse correlation of methylated PhIP metabolites with a biomarker of carcinogenesis and the detection of a novel methylated PhIP metabolite.
杂环芳香胺，如2-氨基-1-甲基-6-苯基咪唑[4,5-b]吡啶（PhIP），是含蛋白质食物加热过程中产生的致癌化合物。伞形科蔬菜可抑制PhIP激活酶，而十字花科蔬菜既能诱导PhIP激活酶又能诱导其解毒酶。
我们研究了这些蔬菜单独或联合使用对大鼠PhIP代谢及结肠DNA加合物形成的影响。
给雄性Wistar大鼠喂食十字花科蔬菜（21%，重量比）、伞形科蔬菜（21%，重量比）或两种蔬菜的组合（每种10.5%重量比）。阴性和阳性对照组喂食AIN-93G饮食。6天后，除阴性对照组仅给予赋形剂外，所有组腹腔注射PhIP（10 mg·kg体重-1）。注射后收集24小时尿液用于液相色谱-串联质谱代谢组学分析。在第7天，处死大鼠并处理组织。
与阳性对照组相比，十字花科蔬菜增加了肝脏PhIP激活酶的活性[细胞色素P450（CYP）1A1（P = 0.0006）和CYP1A2（P < 0.0001）分别增加39.5%和45.1%]，尿苷5'-二磷酸葡萄糖醛酸基转移酶1A（PhIP解毒酶）增加24.5%（P = 0.0267）。伞形科蔬菜未抑制PhIP激活酶，但结肠PhIP-DNA加合物减少20.4%（P = 0.0496）。代谢组学分析表明，伞形科蔬菜增加了尿中甲基化PhIP代谢物的相对丰度。这些甲基化代谢物的总和与结肠PhIP-DNA加合物呈负相关（r = -0.43，P = 0.01）。我们检测到一种新的甲基化尿PhIP代谢物，并证明甲基化代谢物在人肝脏S9组分中产生。
伞形科蔬菜未抑制大鼠PhIP激活酶的活性，提示PhIP-DNA加合物的减少可能涉及其他途径。鉴于甲基化PhIP代谢物与致癌生物标志物呈负相关以及检测到一种新的甲基化PhIP代谢物，有必要进一步研究PhIP甲基化在致癌物代谢中的重要性。
