Apple juice intervention modulates expression of ARE-dependent genes in rat colon and liver.
BACKGROUND
The risk of cancer and other degenerative diseases is inversely correlated with consumption of fruits and vegetables. This beneficial effect is mainly attributed to secondary plant constituents such as polyphenols, supposed to play a major role in protection against ROS (reactive oxygen species)-associated toxicity.


OBJECTIVE
To elucidate the potential of differently manufactured apple juices (clear AJ/cloudy AJ/smoothie, in comparison with a polyphenol-free control juice) to modulate expression of ARE-dependent genes.


METHODS
In male Sprague-Dawley rats (n = 8/group; 10d juice intervention, 4d wash-out; 4 treatment cycles), expression of target genes (superoxide dismutase, SOD1/SOD2; glutathione peroxidase, GPX1/GPX2; γ-glutamylcysteine ligase, GCLC/GCLM; glutathione reductase, GSR; catalase, CAT; NAD(P)H:quinone oxidoreductase-1, NQO1 and transcription factor erythroid-derived 2-like-2, Nrf2) was quantified with duplex RT-PCR, using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as control.


RESULTS
In colon and liver of rats consuming polyphenol-free control juice, rather similar basic expressions were observed (relative GAPDH ratios ranging from 2 to 0.7 and 2.5-0.3, respectively). In the distal colon, apple juice intervention slightly but significantly induced most genes (e.g. GPX2, GSR, CAT, Nrf2; p < 0.001), whereas in the liver only GPX1 and NQO1 mRNA were up-regulated; other hepatic target genes were not affected or down-regulated (SOD1, SOD2, GCLC/M, GSR), concomitant with the absence of Nrf2 induction. Induction of antioxidant gene expression differed with juice type (cloudy AJ > clear AJ ~ smoothie).


CONCLUSIONS
Taken together, the results underline the potential of polyphenol-rich apple juice to increase the expression of ARE-dependent antioxidant genes.
Soyalan
Bülent
B
Faculty of Chemistry, Food Chemistry & Toxicology, University of Kaiserslautern, Kaiserslautern, Germany. bsoyalan@yahoo.de
Minn
Jutta
J
Schmitz
Hans J
HJ
Schrenk
Dieter
D
Will
Frank
F
Dietrich
Helmut
H
Baum
Matthias
M
Eisenbrand
Gerhard
G
Janzowski
Christine
C
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001628:Beverages / Q000032:analysis*; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D003106:Colon / Q000378:metabolism*; D004151:Dipeptides / Q000235:genetics / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology*; D005638:Fruit / Q000737:chemistry; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D027845:Malus / Q000737:chemistry*; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress; D010636:Phenols / Q000494:pharmacology*; D059808:Polyphenols; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D015854:Up-Regulation; D014675:Vegetables / Q000737:chemistry; D000094765:Glutathione Peroxidase GPX1; D000099156:Superoxide Dismutase 2
D000975:Antioxidants; D002374:Catalase; D004151:Dipeptides; D005419:Flavonoids; D005979:Glutathione Peroxidase; D016660:NAD(P)H Dehydrogenase (Quinone); D010636:Phenols; D059808:Polyphenols; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000094765:Glutathione Peroxidase GPX1; D000099156:Superoxide Dismutase 2; C525844:glutathione peroxidase 2, rat; C000606292:Sod1 protein, rat; C507703:NQO1 protein, rat; C017341:gamma-glutamylcysteine