• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.656-663
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• 2001

The most representative nitrosamine derived from nicotine, nitrosamine-4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone(NNK), has been reported to cause lung cancer in A/J mice. It has been also demonstrated that NNK-induced lung tumorigenesis involves $O^6-methylguanine(O^6MeG)$ formation, leading to $GC\;{\rightarrow}\;AT$ transitional mispairing during DNA replication. Our in vitro experiment, modified from the method of DBA assay, examined the ability of phyto-extract mixture to inhibit the metabolism of nicotine to nitrosamines. The production of nitromorpholine from morpholine was inhibited about 75% at the concentration of 20 mg/mL of phyto-extract mixture, which was lower than vitamine C and green tea powder. NNK, which is a pro-carcinogen in laboratory animals, is hydroxylated primarily in liver and lung by CYP 1A2, 2A6 and 3A4. A critical phase. of NNK activation is its change to an unstable metabolite methyl-diazohydroxide via CYP-mediated ${\alpha}-hydroxylation$; and then it provides a methyl group to the DNA to form DNA adducts which can easily induce mutations. $Aroclor^R$ 1254 was used to induce CYPs in the liver of a Sprague-Dawley rat. The ability of various test samples to inhibit CYPs that participate in NNK activation was evaluated, following the removal of the liver from the rat. Microsomal CYPlA2 catalyzing the conversion of NNK into strong carcinogenic chemicals was inhibited more efficiently by phyto-extract mixture than green tea powder. These results indicate that phyto-extract mixture can be used to reduce $O^6MeG$ DNA adducts for chemoprevention.

• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.292-298
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• 2014

Tridemorph is a systemic morpholine fungicide for crops. The objective of this study was to develop reliable and sensitive analytical method for determination of tridemorph residues in tea samples for ensuring the food safety. Tridemorph residues in samples were extracted with acetonitrile after hydration, partitioned with saline water, and then purified using an aminopropyl ($NH_2$) SPE cartridge. The purified samples were detected and quantified using LC-ESI-MS/MS. The linear detection limits for tridemorph ranged from 0.02 to $1.0mgL^{-1}$ with a correlation coefficient of 0.9999. The method was validated using tea samples spiked with tridemorph at different concentration levels (0.02 and $0.05{\mu}gmL^{-1}$). The average recovery ranged between 75.0 and 84.7% with relative standard deviations less than 10%. The LOD and LOQ were 0.01 and $0.02mgL^{-1}$, respectively. The developed method was applied successfully to the identification of tridemorph in real tea samples obtained from different sources, and tridemorph was not detected in any of the samples. The results show that the developed analytical method is accurate and suitable for tridemorph determination in tea samples.