Abstract
Cocoa is a rich source of polyphenols, especially flavanols and procyanidin oligomers, with antioxidant properties, providing protection against oxidation and nitration. Cocoa phenolic compounds are usually extracted with methanol/ethanol solvents in order to obtain most of their bioactive compounds; however, aqueous extraction seems more representative of the physiological conditions. In this study, an aqueous extract of cocoa powder has been prepared and chemically characterized, and its potential protective effect against chemically-induced oxidative stress has been tested in differentiated human neuroblastoma SH-SY5Y cells. Neuronal-like cultured cells were pretreated with realistic concentrations of cocoa extract and its major monomeric flavanol component, epicatechin, and then submitted to oxidative stress induced by a potent pro-oxidant. After one hour, production of reactive oxygen species was evaluated by two different methods, flow cytometry and in situ fluorescence by a microplate reader. Simultaneously, reduced glutathione and antioxidant defense enzymes glutathione peroxidase and glutathione reductase were determined and the results used for a comparative analysis of both ROS (reactive oxygen species) methods and to test the chemo-protective effect of the bioactive products on neuronal-like cells. The results of this approach, never tested before, validate both analysis of ROS and indicate that concentrations of an aqueous extract of cocoa phenolics and epicatechin within a physiological range confer a significant protection against oxidative insult to neuronal-like cells in culture.
Highlights
The water soluble extract was used for cell culture assays. This water soluble cocoa extract was re-suspended in methanol/H2 O (50:50 v/v acidified with formic acid 0.1%), filtered (0.45 μm), and placed in vials for subsequent high performance liquid chromatography (HPLC) coupled to Quadrupole Time-of-Flight Mass Spectrometry (QTOF-MS) detection of phenolic compounds
Flavan-3-ols and flavonols were the polyphenolic groups identified in cocoa powder and represented 96 and 4%, respectively
Regarding flavan-3-ols, catechin and epicatechin were identified with commercial standard, whereas oligomeric procyanidins were identified based on their molecular masses
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Cognitive abilities are progressively deteriorated throughout the adult lifespan [1]. Endogenous, and environmental factors determine the decline of memory, attention, execution, and processing speed, aging being the greatest risk factor for cognitive deterioration and dementia [2]. The etiology of these processes is not well understood, it is presumed that it is related to an increase in oxidative stress and a reduction in the function of the immune system [3]
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