Polyphenols Beyond Barriers: A Glimpse into the Brain

Abstract

BackgroundAgeing can be simply defined as the process of becoming older, which is genetically determined but also environmentally modulated. With the continuous increase of life expectancy, quality of life during ageing has become one of the biggest challenges of developed countries. The quest for a healthy ageing has led to the extensive study of plant polyphenols with the aim to prevent age-associated deterioration and diseases, including neurodegenerative diseases. The world of polyphenols has fascinated researchers over the past decades, and in vitro, cell-based, animal and human studies have attempted to unravel the mechanisms behind dietary polyphenols neuroprotection.MethodsIn this review, we compiled some of the extensive and ever-growing research in the field, highlighting some of the most recent trends in the area.ResultsThe main findings regarding polypolyphenols neuroprotective potential performed using in vitro, cellular and animal studies, as well as human trials are covered in this review. Concepts like bioavailability, polyphenols biotransformation, transport of dietary polyphenols across barriers, including the blood-brain barrier, are here explored.ConclusionThe diversity and holistic properties of polypolyphenol present them as an attractive alternative for the treatment of multifactorial diseases, where a multitude of cellular pathways are disrupted. The underlying mechanisms of polypolyphenols for nutrition or therapeutic applications must be further consolidated, however there is strong evidence of their beneficial impact on brain function during ageing. Nevertheless, only the tip of the iceberg of nutritional and pharmacological potential of dietary polyphenols is hitherto understood and further research needs to be done to fill the gaps in pursuing a healthy ageing.

The Effect of (Poly)phenol-Rich Interventions on Cognitive Functions and Neuroprotective Measures in Healthy Aging Adults: A Systematic Review and Meta-Analysis

“…In addition to the used polyphenol dose, the bioavailability of the ingested phenolic compounds is usually reported as an important factor influencing the change on cognition and brain function [57,58]. From a pharmacological perspective, bioavailability is the rate and extent to which the bioactive compound is absorbed and becomes available at the site of action [59].…”

“…From a pharmacological perspective, bioavailability is the rate and extent to which the bioactive compound is absorbed and becomes available at the site of action [59]. In other words, this rate reflects the ability of the bioactive compound to cross membranes/barriers and to reach the tissues in an appropriate amount of time to exert its effect [57,60]. Variation in phenolic bioavailability ranges from 0.3% to 43% [21], with isoflavones (≈43%) and Gallic acid (≈38%) representing the most well-absorbed polyphenols, followed by catechins (≈18%), flavanones (≈9%), and quercetin glucosides (≈2.5%); the least well-absorbed polyphenols (<1%) are the proanthocyanidins, the galloylated tea catechins, and the anthocyanins [61,62].…”

Neuroprotective Effects of Quercetin in Alzheimer’s Disease

“…The neuroprotective efficacy of quercetin has been studied in both in vitro and in vivo models [50,110,111]. A study using drug screening in Caenorhabditis elegans nematodes with neuronal expression of human exon-1 huntingtin (128Q) and mutant Htt striatal cells derived from knock-in HD mice, concluded that isoquercetin improved motor functions in acute spinal cord injury, reduced α-synuclein fibrillization, reduced hippocampal neuronal cell death, improved synaptic plasticity, and reversed histopathological hallmarks of AD [112]. Quercetin also protects against mitochondrial dysfunction and progressive dopaminergic neurodegeneration by activating PKD1-Akt cell survival signaling axis Cell Culture and MitoPark transgenic mouse models of Parkinson's disease [113].…”

BacHBerry: BACterial Hosts for production of Bioactive phenolics from bERRY fruits

“…Polyphenol content and composition can vary substantially between fleshyfruit varieties Miladinović et al 2014;Kula et al 2016), different cultivation conditions (Josuttis et al 2013;Vagiri et al 2013;Mazur et al 2014), harvest times and as a result of different post-harvest factors (Kårlund et al 2014;Stavang et al 2015), but particularly between species (Moyer et al 2001;McDougall et al 2008;Ruiz et al 2010;Marhuenda et al 2016). Furthermore, plant polyphenols are increasingly being associated with putative bioactivities offering protection against several cardiovascular (Goszcz et al 2015) and neurological diseases (Figueira et al 2017). The hydroxystilbenes are a group of polyphenols with a C 6 -C 2 -C 6 skeleton with two or more hydroxyl groups, where a central carbon-carbon double bond is conjugated with two phenolic moieties (Quideau et al 2011;Kasiotis et al 2013).…”

“…b PCA plots of the full dataset without reference material and blanks in negative mode. Components (Scr) 1 and 2 explain 13.20 and 10.30% of the variation respectively (Figueira et al 2017;Goszcz et al 2015 (Figueira et al 2017). Consequently, polyphenol-based therapies represent an underexplored strategy to minimize the huge social and economic impact of NDs.…”