Abstract
Human health benefits from different polyphenols molecules consumption in the diet, derived mainly by their common activities in the gastrointestinal tract and at the level of blood micro-capillary. In the stomach, intestine and colon, polyphenols act as reducing agents preventing lipid peroxidation, generation and absorption of AGEs/ALEs (advanced glycation end products/advanced lipid oxidation end products) and postprandial oxidative stress. The low absorption of polyphenols in blood does not support their activity as antioxidants and their mechanism of activity is not fully understood. The results are from in vitro, animal and human studies, detected by relevant oxidative stress markers. The review carries evidences that polyphenols, by generating H2O2 at nM concentration, exogenous to cells and organs, act as activators of signaling factors increasing cell Eustress. When polyphenols attain high concentration in the blood system, they generate H2O2 at µM concentration, acting as cytotoxic agents and Distress. Pre-treatment of cells or organisms with polyphenols, by generating H2O2 at low levels, inhibits cellular PTPs (protein tyrosine phosphatases), inducing cell signaling through transcription of the Nrf2 (nuclear factor erythroid 2-related factor 2) axis of adaptation and protection to oxidation stress. Polyphenols ingestion at the right amount and time during the meal acts synergistically at the level of the gastrointestinal tract (GIT) and blood system, for keeping the redox homeostasis in our organism and better balancing human health.
Highlights
Epidemiological, clinical and animal studies have supported a role of polyphenols in the prevention of chronic diseases, such as cardiovascular, diabetes, neurodegenerative and cancer
By generating H2 O2 in the blood system, at the endothelial cell membranous exogenous area, act as activators of signaling factors, increasing cell adaptation and survival
Eberhardt et al reported inhibition of tumor cell proliferation in vitro by polyphenols, extracted from apples, and published those results in the Nature Journal [39]. The suggestion that these compounds inhibit proliferation of tumor cells was not examined critically. We found that those effects were developed by interaction of polyphenols with the cell culture media, in vitro, generating H2 O2
Summary
Epidemiological, clinical and animal studies have supported a role of polyphenols in the prevention of chronic diseases, such as cardiovascular, diabetes, neurodegenerative and cancer. Polyphenols are plant secondary metabolites exhibiting central functions in plant protection against various biotic and abiotic stresses by their potential to act as reducing agents, activate signaling factors and interact with cytotoxic agents. In plants, they have antimicrobial, antiviral, antifungal, anti-insects, anti-herbivores, wound-healing, drought and UV protection properties [4]. By generating H2 O2 in the blood system, at the endothelial cell membranous exogenous area, act as activators of signaling factors, increasing cell adaptation and survival. Because the low bioavailability of nutritional polyphenols and metabolized compounds in the human blood system are mostly around 0.1–2 μM [1,2], they act at the level of the cell membrane by generating H2 O2 , penetrating in cells by 0.01–0.1 μM to improve adaptation and survival of the organism
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