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Oxidative Medicine and Cellular Longevity
Volume 2017, Article ID 1767198, 12 pages
Research Article

Apple Flavonoids Suppress Carcinogen-Induced DNA Damage in Normal Human Bronchial Epithelial Cells

1Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada
2Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada

Correspondence should be addressed to H. P. Vasantha Rupasinghe; ac.lad@ehgnisapurv

Received 4 January 2017; Accepted 2 May 2017; Published 18 June 2017

Academic Editor: Debasish Roy

Copyright © 2017 Vazhappilly Cijo George and H. P. Vasantha Rupasinghe. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Scope. Human neoplastic transformation due to DNA damage poses an increasing global healthcare concern. Maintaining genomic integrity is crucial for avoiding tumor initiation and progression. The present study aimed to investigate the efficacy of an apple flavonoid fraction (AF4) against various carcinogen-induced toxicity in normal human bronchial epithelial cells and its mechanism of DNA damage response and repair processes. Methods and Results. AF4-pretreated cells were exposed to nicotine-derived nitrosamine ketones (NNK), NNK acetate (NNK-Ae), methotrexate (MTX), and cisplatin to validate cytotoxicity, total reactive oxygen species, intracellular antioxidants, DNA fragmentation, and DNA tail damage. Furthermore, phosphorylated histone (γ-H2AX) and proteins involved in DNA damage (ATM/ATR, Chk1, Chk2, and p53) and repair (DNA-PKcs and Ku80) mechanisms were evaluated by immunofluorescence and western blotting, respectively. The results revealed that AF4-pretreated cells showed lower cytotoxicity, total ROS generation, and DNA fragmentation along with consequent inhibition of DNA tail moment. An increased level of γ-H2AX and DNA damage proteins was observed in carcinogen-treated cells and that was significantly () inhibited in AF4-pretreated cells, in an ATR-dependent manner. AF4 pretreatment also facilitated the phosphorylation of DNA-PKcs and thus initiation of repair mechanisms. Conclusion. Apple flavonoids can protect in vitro oxidative DNA damage and facilitate repair mechanisms.