About this Research Topic
Polyphenols are secondary metabolites produced by plants as a defense mechanism against pathogens, UV, and predators. These bioactive compounds, found in plant-based foods and beverages, exert various beneficial effects on human health. In vitro, pre-clinical and human clinical intervention studies have highlighted the pleiotropic features of these bioactive compounds and show the protective role of polyphenols against the development of chronic diseases such as type 2 diabetes, cardiovascular and neurodegenerative diseases. Additional studies have also supported (poly)phenols’ cognitive beneficial outcomes and neuroprotective potential.
In spite of the large body of evidence supporting the health benefits of a polyphenol-rich diet, most molecular mechanisms of action remain to be unraveled. One of the biggest challenges in elucidating the molecular mechanisms of action of dietary polyphenols on human health is to possess the knowledge of the bioactive form at their site(s) of action and their bioavailability.
In certain areas of human physiology, research on the health benefits of polyphenols has progressed and mechanisms start to be elucidated. The modulation of blood glucose by polyphenols is quite well documented: strong evidence showed that the inhibition of glucose digestive enzymes and the modulation of glucose transporters and lipid metabolism by polyphenols exert beneficial effects on glucose homeostasis. Similarly, the direct action of polyphenols on endothelial cells via the modulation of reactive oxygen species-lowering enzymes, confers protective cardiovascular properties to these bioactive compounds.
Surprisingly, the action of polyphenols on brain function is not as widely documented as it should be, given the pleiotropic effects polyphenol may exert on the central nervous system (CNS). Evidence in support of the transport of polyphenol metabolites across the BBB from in vitro and animal models is reported in the literature. There are a few cellular and animal models’ studies supporting polyphenols’ neuroprotective role, suggesting at least a potential modulating effect in the progression of neurodegenerative diseases. This is still unclear and doses reported are still far from achievable through either diet or supplements’ intake. Additionally, a wider diversity of polyphenolic compounds needs to be assessed on various CNS functions and on different experimental models.
This Research Topic aims at gathering original and review articles covering, but not limited to, the following subjects:
- Polyphenolic compounds, oxidative stress, and neuroinflammation attenuation – experimental evidence in reference to neuroinflammatory processes
- Evidence, in vitro and in vivo in support of polyphenols’ neuroprotective role/ neurodegenerative diseases
- Polyphenols’ action on cognitive functions, learning, and memory - Experimental evidence dissecting the impact on neuronal plasticity
- Polyphenols and HPA axis – potential influence on cortisol levels’ lowering
- Polyphenols’ modulation of the gut-brain axis
Keywords: Polyphenols, neuroprotection, neuroinflammation, cognition, gut-brain axis
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