Inês Figueira

Neuroprotective effects of digested polyphenols from wild blackberry species

PurposeBlackberry ingestion has been demonstrated to attenuate brain degenerative processes with the benefits ascribed to the (poly)phenolic components. The aim of this work was to evaluate the neuroprotective potential of two wild blackberry species in a neurodegeneration cell model and compare them with a commercial variety.MethodsThis work encompasses chemical characterization before and after an in vitro digestion and the assessment of neuroprotection by digested metabolites. Some studies targeting redox/cell death systems were also performed to assess possible neuroprotective molecular mechanisms.ResultsThe three blackberry extracts presented some quantitative differences in polyphenol composition that could be responsible for the different responses in the neurodegeneration cell model. Commercial blackberry extracts were ineffective but both wild blackberries, Rubus brigantinus and Rubus vagabundus, presented neuroprotective effects. It was verified that a diminishment of intracellular ROS levels, modulation of glutathione levels and activation of caspases occurred during treatment. The last effect suggests a preconditioning effect since caspase activation was not accompanied by diminution in cell death and loss of functionality.ConclusionsThis is the first time that metabolites obtained from an in vitro digested food matrix, and tested at levels approaching the concentrations found in human plasma, have been described as inducing an adaptative response.

Yap1 mediates tolerance to cobalt toxicity in the yeast Saccharomyces cerevisiae.

BACKGROUND Cobalt has a rare occurrence in nature, but may accumulate in cells to toxic levels. In the present study, we have investigated how the transcription factor Yap1 mediates tolerance to cobalt toxicity. METHODS Fluorescence microscopy was used to address how cobalt activates Yap1. Using microarray analysis, we compared the transcriptional profile of a strain lacking Yap1 to that of its parental strain. To evaluate the extent of the oxidative damage caused by cobalt, GSH was quantified by HPLC and protein carbonylation levels were assessed. RESULTS Cobalt activates Yap1 under aerobiosis and anaerobiosis growth conditions. This metal generates a severe oxidative damage in the absence of Yap1. However, when challenged with high concentrations of cobalt, yap1 mutant cells accumulate lower levels of this metal. Accordingly, microarray analysis revealed that the expression of the high affinity phosphate transporter, PHO84, a well-known cobalt transporter, is compromised in the yap1 mutant. Moreover, we show that Yap1 is a repressor of the low affinity iron transporter, FET4, which is also known to transport cobalt. CONCLUSIONS Cobalt activates Yap1 that alleviates the oxidative damage caused by this metal. Yap1 partially controls cobalt cellular uptake via the regulation of PHO84. Although FET4 repression by Yap1 has no effect on cobalt uptake, it may be its first line of defense against other toxic metals. GENERAL SIGNIFICANCE Our results emphasize the important role of Yap1 in mediating cobalt-induced oxidative damages and reveal new routes for cell protection provided by this regulator.

Polyphenols journey through blood-brain barrier towards neuronal protection.

Age-related complications such as neurodegenerative disorders are increasing and remain cureless. The possibility of altering the progression or the development of these multifactorial diseases through diet is an emerging and attractive approach with increasing experimental support. We examined the potential of known bioavailable phenolic sulfates, arising from colonic metabolism of berries, to influence hallmarks of neurodegenerative processes. In silico predictions and in vitro transport studies across blood-brain barrier (BBB) endothelial cells, at circulating concentrations, provided evidence for differential transport, likely related to chemical structure. Moreover, endothelial metabolism of these phenolic sulfates produced a plethora of novel chemical entities with further potential bioactivies. Pre-conditioning with phenolic sulfates improved cellular responses to oxidative, excitotoxicity and inflammatory injuries and this attenuation of neuroinflammation was achieved via modulation of NF-κB pathway. Our results support the hypothesis that these small molecules, derived from dietary (poly)phenols may cross the BBB, reach brain cells, modulate microglia-mediated inflammation and exert neuroprotective effects, with potential for alleviation of neurodegenerative diseases.

Interventions for age-related diseases: Shifting the paradigm

Over 60% of people aged over 65 are affected by multiple morbidities, which are more difficult to treat, generate increased healthcare costs and lead to poor quality of life compared to individual diseases. With the number of older people steadily increasing this presents a societal challenge. Age is the major risk factor for age-related diseases and recent research developments have led to the proposal that pharmacological interventions targeting common mechanisms of ageing may be able to delay the onset of multimorbidity. Here we review the state of the knowledge of multimorbidity, appraise the available evidence supporting the role of mechanisms of ageing in the development of the most common age-related diseases and assess potential molecules that may successfully target those key mechanisms.

Bioaccessible (poly)phenol metabolites from raspberry protect neural cells from oxidative stress and attenuate microglia activation

Neuroinflammation is an integral part of the neurodegeneration process inherent to several aging dysfunctions. Within the central nervous system, microglia are the effective immune cells, responsible for neuroinflammatory responses. In this study, raspberries were subjected to in vitro digestion simulation to obtain the components that result from the gastrointestinal (GI) conditions, which would be bioaccessible and available for blood uptake. Both the original raspberry extract and the gastrointestinal bioaccessible (GIB) fraction protected neuronal and microglia cells against H2O2-induced oxidative stress and lipopolysaccharide (LPS)-induced inflammation, at low concentrations. Furthermore, this neuroprotective capacity was independent of intracellular ROS scavenging mechanisms. We show for the first time that raspberry metabolites present in the GIB fraction significantly inhibited microglial pro-inflammatory activation by LPS, through the inhibition of Iba1 expression, TNF-α release and NO production. Altogether, this study reveals that raspberry polyphenols may present a dietary route to the retardation or amelioration of neurodegenerative-related dysfunctions.

Protective Effect of a (Poly)phenol-Rich Extract Derived from Sweet Cherries Culls against Oxidative Cell Damage

Oxidative stress is one of the key phenomena behind the most common types of chronic diseases. Therefore, the modulation of oxidative stress is an interesting target for acting either through prevention or as a therapeutic approach. In this work, a Portuguese variety of cherry (Saco Cherry) was processed in order to obtain a potent in vitro antioxidant phenolic-rich extract (Ch-PRE), which was further explored to evaluate its potential application as nutraceutical agent against cellular oxidative stress damage. Ch-PRE was mainly composed of anthocyanins, particularly cyanidin-3-rutinoside, cyanidin-3-glucoside, peonidin-3-glucoside and neochlorogenic acid, and exhibited a potent chemical antioxidant activity expressed by its oxygen radical absorbance capacity (ORAC) and hydroxyl radical averting capacity (HORAC) values. Ch-PRE also displayed effective intracellular radical scavenging properties in intestinal epithelial and neuronal cells challenged with oxidative stress but showed a different order of effectiveness regarding the modulation of endogenous antioxidant system. Ch-PRE could be an attractive candidate to formulate an agent for the prevention of oxidative stress-induced disorders such as intestinal inflammation disorders or with an appropriated delivery system for neurodegenerative diseases.

Polyphenols Beyond Barriers: A Glimpse into the Brain

Background Ageing 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. Methods In 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. Results The 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. Conclusion The 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.

Valuing the Endangered Species Antirrhinum lopesianum: Neuroprotective Activities and Strategies for in vitro Plant Propagation

Plant phytochemicals are described as possessing considerable neuroprotective properties, due to radical scavenging capacity and acetylcholinesterase inhibitory activity, important bioactivities in neurodegeneration. Antirrhinum lopesianum is a rare endemism from the Iberian Peninsula, occurring at the northeastern border between Portugal and Spain. It is classified as Endangered, due to its highly fragmented geographical occupation, facing a high risk of extinction in the Portuguese territory, within 20 years. Here, we describe for the first time the chemical characterization of extracts of the species concerning total phenol content, flavonoid content and antioxidant properties. The profile of high performance liquid chromatography with diode array detector (HPLC-DAD) of the polyphenol-enriched fraction of plant extracts was also performed, showing the great potential of the species as a source of bioactive phytochemical compounds. A. lopesianum’s potential for neuroprotection was revealed by a significant acetylcholinesterase inhibitory activity and also by a neuroprotective effect on a human cell model of neurodegeneration. Moreover, this is the first report describing a successful procedure for the in vitro propagation of this endangered species. The comparison of phenolic content and the HPLC-DAD profile of wild and in vitro propagated plants revealed that in vitro plants maintain the ability to produce secondary metabolites, but the profiles are differentially affected by the growth regulators. The results presented here greatly contribute to the value for this species regarding its potential as a source of phytochemicals with prospective neuroprotective health benefits.

(Poly)phenol-digested metabolites modulate alpha-synuclein toxicity by regulating proteostasis

Parkinson’s disease (PD) is an age-related neurodegenerative disease associated with the misfolding and aggregation of alpha-synuclein (aSyn). The molecular underpinnings of PD are still obscure, but nutrition may play an important role in the prevention, onset, and disease progression. Dietary (poly)phenols revert and prevent age-related cognitive decline and neurodegeneration in model systems. However, only limited attempts were made to evaluate the impact of digestion on the bioactivities of (poly)phenols and determine their mechanisms of action. This constitutes a challenge for the development of (poly)phenol-based nutritional therapies. Here, we subjected (poly)phenols from Arbutus unedo to in vitro digestion and tested the products in cell models of PD based on the cytotoxicity of aSyn. The (poly)phenol-digested metabolites from A. unedo leaves (LPDMs) effectively counteracted aSyn and H2O2 toxicity in yeast and human cells, improving viability by reducing aSyn aggregation and inducing its clearance. In addition, LPDMs modulated pathways associated with aSyn toxicity, such as oxidative stress, endoplasmic reticulum (ER) stress, mitochondrial impairment, and SIR2 expression. Overall, LPDMs reduced aSyn toxicity, enhanced the efficiency of ER-associated protein degradation by the proteasome and autophagy, and reduced oxidative stress. In total, our study opens novel avenues for the exploitation of (poly)phenols in nutrition and health.

Exploring the benefits of cellular models to uncover bioactive polyphenols for neurodegeneration

Our society is currently experiencing increased lifespan; one of the top causes for the high incidence of neurodegenerative disorders. The lack of effective treatments delaying or blocking disease progression has encouraged the active search for novel therapies. Many evidences support the protective role of phytochemicals in the prevention of neurodegenerative diseases, particularly (poly)phenols. In this review, we described the use of cellular-based models of neurodegenerative diseases and the benefits of their use as potent tools in the search for bioactive molecules, particularly (poly)phenols. Studies to assess the biological activity of (poly)phenols involve experimentation with in vitro and in vivo systems. In vitro systems are a useful tool as a first approach to test the underlined molecular mechanisms of candidate molecules. They can provide valuable information about biological activity, which can be then used to design animal and human intervention studies.