Salivary α-amylase, serum albumin, and myoglobin protect against DNA-damaging activities of ingested dietary agents in vitro.
Potent DNA-damaging activities were seen in vitro from dietary chemicals found in coffee, tea, and liquid smoke. A survey of tea varieties confirmed genotoxic activity to be widespread. Constituent pyrogallol-like polyphenols (PLPs) such as epigallocatechin-3-gallate (EGCG), pyrogallol, and gallic acid were proposed as a major source of DNA-damaging activities, inducing DNA double-strand breaks in the p53R assay, a well characterized assay sensitive to DNA strand breaks, and comet assay. Paradoxically, their consumption does not lead to the kind of widespread cellular toxicity and acute disease that might be expected from genotoxic exposure. Existing physiological mechanisms could limit DNA damage from dietary injurants. Serum albumin and salivary α-amylase are known to bind EGCG. Salivary α-amylase, serum albumin, and myoglobin, but not salivary proline-rich proteins, reduced damage from tea, coffee, and PLPs, but did not inhibit damage from the chemotherapeutics etoposide and camptothecin. This represents a novel function for saliva in addition to its known functions including protection against tannins. Cell populations administered repeated pyrogallol exposures had abatement of measured DNA damage by two weeks, indicating an innate cellular adaptation. We suggest that layers of physiological protections may exist toward natural dietary products to which animals have had high-level exposure over evolution.
Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
M Zulfiquer
MZ
Hossain
Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
Kalpesh
K
Patel
Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA. Electronic address: sk@jhmi.edu.
Scott E
SE
Kern
D002392:Catechin / Q000031:analogs & derivatives; D045744:Cell Line, Tumor; D040503:Coffea / Q000737:chemistry*; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D004032:Diet; D005707:Gallic Acid / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D009211:Myoglobin / Q000494:pharmacology*; D059808:Polyphenols / Q000494:pharmacology; D020011:Protective Agents / Q000494:pharmacology; D011748:Pyrogallol / Q000494:pharmacology; D055291:Salivary alpha-Amylases / Q000494:pharmacology*; D012709:Serum Albumin / Q000494:pharmacology*; D013662:Tea / Q000737:chemistry*
D009211:Myoglobin; D059808:Polyphenols; D020011:Protective Agents; D012709:Serum Albumin; D013662:Tea; D011748:Pyrogallol; D005707:Gallic Acid; D002392:Catechin; C045651:epigallocatechin gallate; D055291:Salivary alpha-Amylases
Clastogen; EGCG; Gallic acid; Genotoxin; Pyrogallol; p53