title: Cranberries and wild blueberries treated with gastrointestinal enzymes positively modify glutathione mechanisms in Caco-2 cells in vitro.
abstract: Beneficial health effects of cranberries (CBs) and wild blueberries (BBs), such as reduced levels of oxidative stress, have been demonstrated in feeding studies. These Vaccinium berries contain high levels of flavonoids; however, the bioavailability of flavonoids is generally low. We investigated the in vitro effects of these berries on intestinal cells, focusing on mitigating oxidative stress and associated reactive oxygen species (ROS). First, we simulated the passage of CB and BB through the gastrointestinal (GI) tract by treating berry homogenates to a battery of digestive enzymes. Then, Caco-2 cells, a model of small intestine epithelial uptake, were exposed to these homogenates for 60 min. Using a cell-free assay, we found that the antioxidant activity in CB homogenates was not affected by these enzymes, but that BB homogenates treated with gut enzymes had 43% lower free-radical quenching activity (P < 0.05). However, both of the enzyme-treated homogenates were still able to counteract the ROS-generating ability of H2O2 added exogenously to Caco-2 cells. Berry homogenates also increased mitochondrial metabolic rates at 60 min posttreatment, as measured by MTT assays. Enzyme-treated CB (but not BB) homogenates increased the levels of reduced glutathione (GSH) relative to oxidized glutathione (GSSG), a critical indicator of the cellular redox state (P < 0.05). Our data suggest that CBs do not lose their antioxidant ability when passing through the GI tract, and specifically, digested CB may serve to enhance cytoprotective effects in intestinal cells by reducing potential damage caused by free radicals and ROS derived from other food sources.
authors.affiliation: Dept. of Biology, Univ. of Prince Edward Island, Charlottetown, PE, Canada.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Slemmer
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Livingston-Thomas
authors.forename: Katherine T
authors.initials: KT
authors.lastname: Gottschall-Pass
authors.forename: Marva I
authors.initials: MI
authors.lastname: Sweeney
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D029798:Blueberry Plants / Q000737:chemistry*; D018938:Caco-2 Cells; D002470:Cell Survival / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology; D005638:Fruit / Q000737:chemistry*; D041981:Gastrointestinal Tract / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D029799:Vaccinium macrocarpon / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010936:Plant Extracts; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D005978:Glutathione; D019803:Glutathione Disulfide