Polyphenols and DNA Damage: A Mixed Blessing

Abstract

Polyphenols are a very broad group of chemicals, widely distributed in plant foods, and endowed with antioxidant activity by virtue of their numerous phenol groups. They are widely studied as putative cancer-protective agents, potentially contributing to the cancer preventive properties of fruits and vegetables. We review recent publications relating to human trials, animal experiments and cell culture, grouping them according to whether polyphenols are investigated in whole foods and drinks, in plant extracts, or as individual compounds. A variety of assays are in use to study genetic damage endpoints. Human trials, of which there are rather few, tend to show decreases in endogenous DNA damage and protection against DNA damage induced ex vivo in blood cells. Most animal experiments have investigated the effects of polyphenols (often at high doses) in combination with known DNA-damaging agents, and generally they show protection. High concentrations can themselves induce DNA damage, as demonstrated in numerous cell culture experiments; low concentrations, on the other hand, tend to decrease DNA damage.

Melatonin reduces inflammatory response in human intestinal epithelial cells stimulated by interleukin‐1β

“…DNA damage is largely linked to ROS production in inflammatory conditions, including IBD . The protective effect of antioxidant molecules via a decrease in oxidative damage to DNA has been shown in various models . To assess the protective effect of melatonin on the IL‐1β‐induced oxidative damage to DNA, we quantified the DNA‐breakage by COMET.…”

“…60 The protective effect of antioxidant molecules via a decrease in oxidative damage to DNA has been shown in various models. 61 To assess the protective effect of melatonin on the IL-1β-induced oxidative damage to DNA, we quantified the DNA-breakage F I G U R E 6 Effects of melatonin on the transport of fluorescein sulfonic acid (FSA) across Caco-2 cell monolayers. Cells were incubated in the absence of additional treatment (control), preincubated in the absence of additional treatment and subsequently incubated for 24 h with 10 ng/mL IL-1β, or preincubated for 1 h in the presence of melatonin and subsequently co-incubated for 24 h with or without 10 ng/mL IL-1β.…”

Mediterranean Diet Nutrients to Turn the Tide against Insulin Resistance and Related Diseases

“…Furthermore, the in vivo safety of high doses of pure compounds (over 100 times higher than the natural occurrence in some cases) is unlikely to be feasibly extrapolated from in vitro mechanistic research, with several studies reporting the increased risk of hepatotoxicity [234], and others highlighting the increased risk of stroke and premature death [235], and even carcinogenesis [236]. As a consequence, more investigations are needed to establish which dosages of the isolated polyphenol compounds are safe and effective for clinical use, testing first the concentrations close to those present in humans as a result of a healthy dietary intake [237]. Finally, even for some of the most promising dietary supplements explored in this review, longer follow-up periods and larger sample sizes are essential to assess the interventions' outcomes in the long run [119][120][121]123,138].…”

Association between Polyphenol Intake and Breast Cancer Risk by Menopausal and Hormone Receptor Status

“…Polyphenol consumption could reduce the risk of cancer development through various mechanisms [2][3][4][5], protecting against DNA damage [6], blocking specific carcinogen pathways [7], inducing apoptosis [8], acting as antioxidant and anti-inflammatory agents [9], inhibiting angiogenesis [10], and/or suppressing matrix metalloproteinase secretion and tumor invasiveness [11].…”