Abstract
The prevalence of cytoprotective mechanisms induced by polyphenols such as activation of intracellular antioxidant responses (ICM) and direct free radical scavenging was investigated in native Chilean species of strawberries, raspberries, and currants. Human gastric epithelial cells were co- and preincubated with polyphenolic-enriched extracts (PEEs) from Chilean raspberries (Rubus geoides), strawberries (Fragaria chiloensis ssp. chiloensis f. chiloensis), and currants (Ribes magellanicum) and challenged with peroxyl and hydroxyl radicals. Cellular protection was determined in terms of cell viability, glyoxalase I and glutathione s-transferases activities, and carboxymethyl lysine (CML) and malondialdehyde levels. Our results indicate that cytoprotection induced by ICM was the prevalent mechanism for Rubus geoides and F. chiloensis. This agreed with increased levels of glyoxalase I and glutathione S-transferase activities in cells preincubated with PEEs. ORAC index indicated that F. chiloensis was the most efficient peroxyl radical scavenger. Moreover, ICM mediated by F. chiloensis was effective in protecting cells from CML accumulation in contrast to the protective effects induced by free radical scavenging. Our results indicate that although both polyphenol-mediated mechanisms can exert protective effects, ICM was the most prevalent in AGS cells. These results suggest a potential use of these native berries as functional food.
Highlights
Oxidative stress has been implied in the etiology of numerous diseases as well as in the ageing process [1,2,3]
To get more insights regarding the protection afforded by polyphenols from the South American relatives of commercial berries on AGS cells exposed to a free radical source, in the present work, we have addressed studies aimed to assess the cytoprotective mechanisms mediated by the polyphenols contained in the Chilean native raspberry Rubus geoides, the native currant Ribes magellanicum, and the Chilean strawberry Fragaria chiloensis ssp. chiloensis f. chiloensis
In the case of the studies about the free radical scavenging and/or metal-chelating activity of PPEs, AGS cells were simultaneously incubated with each polyphenolic-enriched extracts (PEEs) and the free radical sources
Summary
Oxidative stress has been implied in the etiology of numerous diseases as well as in the ageing process [1,2,3]. It has been suggested that the intake of dietary antioxidants is inversely associated with the development of chronic diseases, which currently constitute the main cause of mortality worldwide [6]. Dietary interventions in humans, as well as in vitro studies, have shown evidence regarding the beneficial effects on the health related to the consumption of berries [7]. These effects have been mainly attributed to their content of polyphenols, which can protect biological systems against the damage induced by numerous agents, including free radicals [8, 9]. Cellular protection mediated by polyphenols against free radical-induced damage can be exerted by different mechanisms, including scavenging of free radicals by direct reactions, metal ion complexation with a consequent inhibition of the free radicals generated through Fenton-type reactions, and activation of the intracellular signaling cascades
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