Oltipraz is an Nrf2 activator. Users of Nrf2 activators report positive experiences.
RESEARCH ARTICLE (from pubmed.gov):
Hepatology. 2007 Nov;46(5):1597-610.
Oxidative and electrophilic stress induces multidrug resistance-associated protein transporters via the nuclear factor-E2-related factor-2 transcriptional pathway.
Multidrug resistance-associated proteins (Mrps) are adenosine triphosphate-dependent transporters that efflux chemicals out of cells. In the liver, Mrp2 transports bilirubin-glucuronide, glutathione (GSH), and drug conjugates into bile, whereas Mrp3 and Mrp4 efflux these entities into blood. The purpose of this study was to determine whether oxidative conditions (that is, the disruption of hepatic GSH synthesis) or the administration of nuclear factor-E2-related factor-2 (Nrf2) activators (oltipraz and butylated hydroxyanisole) can induce hepatic Mrp transporters and whether that induction is through the Nrf2 transcriptional pathway. Livers from hepatocyte-specific glutamate-cysteine ligase catalytic subunit-null mice had increased nuclear Nrf2 levels, marked gene and protein induction of the Nrf2 target gene NAD(P)H:quinone oxidoreductase 1, as well as Mrp2, Mrp3, and Mrp4 expression. The treatment of wild-type and Nrf2-null mice with oltipraz and butylated hydroxyanisole demonstrated that the induction of Mrp2, Mrp3, and Mrp4 is Nrf2-dependent. In Hepa1c1c7 cells treated with the Nrf2 activator tert-butyl hydroquinone, chromatin immunoprecipitation with Nrf2 antibodies revealed the binding of Nrf2 to antioxidant response elements in the promoter regions of mouse Mrp2 [-185 base pairs (bp)], Mrp3 (-9919 bp), and Mrp4 (-3767 bp).CONCLUSION:
The activation of the Nrf2 regulatory pathway stimulates the coordinated induction of hepatic Mrps.
PMID: 17668877 [PubMed - indexed for MEDLINE]
[INTERPRETATION: Oltipraz activates Nrf2, which then induces transportation of chemicals out of liver cells. Nrf2 is tied to antioxidant responses to protect the liver.]
RESEARCH ARTICLE (from pubmed.com):
Pharmacol. 2007 Dec 22;577(1-3):17-27. Epub 2007 Aug 23.
Nrf2-regulated genes by 3H-1, 2-dithiole-3-thione through the ERK signaling
pathway in murine keratinocytes.
Electrophile and free
radical detoxifying enzymes including NAD(P)H:quinine oxidoreductase 1
(Nqo1) play an important role in the defense system by enhancing cellular
antioxidant capacity. Chemopreventive efficacy of
3H-1,2-dithiole-3-thione (D3T) is mediated through activation of the
transcription factor Nrf2 and subsequent elevation of detoxifying enzymes.
In the present study, we have investigated the potential role of extracellular
signal-regulated kinase (ERK) in regulation of D3T-induced and Nrf2-dependent
gene expression in murine keratinocytes. Expression levels of Nqo1 were
highly inducible by D3T treatment and increased nuclear levels of Nrf2 were
observed in these cells. Treatment with pharmacological inhibitor of ERK1/2
largely blocked nuclear accumulation of Nrf2, ARE-driven reporter gene
expression, and induction of Nqo1, as well as other phase 2 genes. Activation
of ERK1/2 has been demonstrated following treatment with D3T. While, inhibitors
of p38, PKC and PI3K did not affect ARE-driven gene expression. Involvement of
the ERK1/2 cascade in inducible ARE-transcription activities was also observed
in cells treated with other types of inducers oltipraz, sulforaphane and
hydrogen peroxide. Collectively, current study suggests that phosphorylation
cascade via ERK1/2 is associated with the activation process of Nrf2 and
subsequent transactivation of its target gene Nqo1 following treatment with
dithiolethione in murine keratinocyte.
[PubMed - indexed for MEDLINE]
[INTERPRETATION: Activation of Nrf2 is effective in raising levels of enzymes that detoxify cells, which then prevents cancer. Oltipraz activates Nrf2 by causing low levels of antioxidants, so Nrf2 instructs the genes to make more.]
RESEARCH ARTICLE (from pubmed.gov)
J Biochem Mol Toxicol. 2008
Mar-Apr;22(2):128-35. doi: 10.1002/jbt.20225.
Induction of drug
metabolism enzymes and transporters by oltipraz in rats.
regulation of Phase-I and -II enzymes with xenobiotic transporters has been
shown after treatment with microsomal enzyme inducers. The chemopreventive
agent oltipraz (OPZ) induces Phase-I and -II drug-metabolizing enzymes such
as CYP2B and NQO1. The purpose of this study was to examine the regulation of
drug-metabolizing enzymes and transporters in response to OPZ treatment and to
investigate a potential role for constitutive androstane receptor (CAR) in
OPZ-mediated induction. Sprague-Dawley rats treated with OPZ exhibited
increased mRNA and protein levels of both Nqo1 and Cyp2b1/2 by 24 h. To examine
whether OPZ activates transporter gene expression via CAR, sexually dimorphic
male and female Wistar-Kyoto (WKY) rats were treated with OPZ and mRNA levels
quantified by bDNA signal amplification. OPZ induced Ugt1a6 and Ugt2b1 in males
significantly higher than in females, indicating a CAR-dependent mechanism of
induction. However, OPZ induced microsomal epoxide hydrolase, NAD(P)H quinone
oxidoreductase, and Cyp3a1/23 equally in both genders, indicating a
CAR-independent mechanism of induction of these genes. Similarly, the transporters
Mdr1a, Mdr1b, Mrp3, and Mrp4 were induced by OPZ without any apparent
difference between genders. In summary, OPZ coordinately increases multiple
hepatic xenobiotic transporter mRNA levels, along with Phase-I and -II
enzymes some of which may occur through CAR-dependent mechanisms.
Periodicals, Inc. PMID: 18418891
[PubMed - indexed for MEDLINE]
[INTERPRETATION: Oltipraz prevents cancer by stimulating genes to produce protective enzymes in the liver.]