ABSTRACT
In this study, the effect of myrosinase-treated glucoerucin (GER+MYR), which releases the isothiocyanate (ITC) erucin, on heme oxygenase 1 (HO-1) gene expression and Nrf2 signaling was investigated in vitro in cultured cells and in vivo in mice. Treatment of HT-29 cells with GER+MYR resulted in a significant increase in the mRNA and protein levels of nuclear Nrf2 and HO-1. GER+MYR was more potent at enhancing the nuclear Nrf2 levels than were the following myrosinase-treated glucosinolates: sinigrin, glucoraphanin and gluconasturtiin, which are the precursors of allyl-ITC, R-sulforaphane and 2-phenylethyl ITC, respectively. GER+MYR also significantly induced HO-1 gene expression in the mouse intestinal mucosae and liver but not in the brain. Mechanistic studies suggest that GER+MYR induces Nrf2 via ERK1/2-, p38- and JNK-dependent signal transduction pathways. The GER+MYR-mediated increase in HO-1 expression is primarily attributable to p38 signaling.
Subject(s)
Glucose/analogs & derivatives , Heme Oxygenase-1/metabolism , Imidoesters/pharmacology , NF-E2-Related Factor 2/metabolism , Animals , Brain/drug effects , Brain/metabolism , Diet, High-Fat/adverse effects , Female , Glucose/pharmacology , Glucosinolates/pharmacology , Glycoside Hydrolases/pharmacology , HT29 Cells , Heme Oxygenase-1/genetics , Humans , Intestinal Mucosa/metabolism , Intestines/drug effects , Isothiocyanates/metabolism , Liver/drug effects , Liver/metabolism , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mice , Mice, Inbred C57BL , Mitogen-Activated Protein Kinase 3/genetics , Mitogen-Activated Protein Kinase 3/metabolism , Mustard Plant/chemistry , NF-E2-Related Factor 2/genetics , Oximes , Plant Extracts/pharmacology , RNA, Messenger/genetics , RNA, Messenger/metabolism , Signal Transduction , Sulfoxides , Up-Regulation , p38 Mitogen-Activated Protein Kinases/genetics , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
Increased tissue status of the long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) is associated with cardiovascular and cognitive benefits. Limited epidemiological and animal data suggest that flavonoids, and specifically anthocyanins, may increase EPA and DHA levels, potentially by increasing their synthesis from the shorter-chain n-3 PUFA, α-linolenic acid. Using complimentary cell, rodent and human studies we investigated the impact of anthocyanins and anthocyanin-rich foods/extracts on plasma and tissue EPA and DHA levels and on the expression of fatty acid desaturase 2 (FADS2), which represents the rate limiting enzymes in EPA and DHA synthesis. In experiment 1, rats were fed a standard diet containing either palm oil or rapeseed oil supplemented with pure anthocyanins for 8 weeks. Retrospective fatty acid analysis was conducted on plasma samples collected from a human randomized controlled trial where participants consumed an elderberry extract for 12 weeks (experiment 2). HepG2 cells were cultured with α-linolenic acid with or without select anthocyanins and their in vivo metabolites for 24 h and 48 h (experiment 3). The fatty acid composition of the cell membranes, plasma and liver tissues were analyzed by gas chromatography. Anthocyanins and anthocyanin-rich food intake had no significant impact on EPA or DHA status or FADS2 gene expression in any model system. These data indicate little impact of dietary anthocyanins on n-3 PUFA distribution and suggest that the increasingly recognized benefits of anthocyanins are unlikely to be the result of a beneficial impact on tissue fatty acid status.