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Activation of anti-oxidant Nrf2 signaling by enone analogues of curcumin
Lorraine M Deck1, Lucy A Hunsaker2, Thomas A Vander Jagt2
1Department of Chemistry and Chemical Biology, University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, NM 87131, USA.
Abstract:
Inflammation and oxidative stress are common in many chronic diseases. Targeting signaling pathways that contribute to these conditions may have therapeutic potential. The transcription factor Nrf2 is a major regulator of phase II detoxification and anti-oxidant genes as well as anti-inflammatory and neuroprotective genes. Nrf2 is widespread in the CNS and is recognized as an important regulator of brain inflammation. The natural product curcumin exhibits numerous biological activities including ability to induce the expression of Nrf2-dependent phase II and anti-oxidant enzymes. Curcumin has been examined in a number of clinical studies with limited success, mainly owing to limited bioavailability and rapid metabolism. Enone analogues of curcumin were examined with an Nrf2 reporter assay to identify Nrf2 activators. Analogues were separated into groups with a 7-carbon dienone spacer, as found in curcumin; a 5-carbon enone spacer with and without a ring; and a 3-carbon enone spacer. Activators of Nrf2 were found in all three groups, many of which were more active than curcumin. Dose-response studies demonstrated that a range of substituents on the aromatic rings of these enones influenced not only the sensitivity to activation, reflected in EC50 values, but also the extent of activation, which suggests that multiple mechanisms are involved in the activation of Nrf2 by these analogues.
Insights
New curcumin analogues activate the Nrf2 pathway, offering potential for treating chronic diseases linked to inflammation and oxidative stress. These compounds show enhanced Nrf2 activation compared to curcumin.
Area of Science:
- Biochemistry and Molecular Biology
- Neuroscience
- Pharmacology
Background:
- Inflammation and oxidative stress are hallmarks of chronic diseases, necessitating therapeutic strategies targeting key signaling pathways.
- The transcription factor Nrf2 (Nuclear factor erythroid 2-related factor 2) is a critical regulator of antioxidant, anti-inflammatory, and neuroprotective genes, particularly in the central nervous system (CNS).
- Curcumin, a natural product, activates Nrf2 but suffers from poor bioavailability and rapid metabolism, limiting its clinical efficacy.
Purpose of the Study:
- To synthesize and evaluate novel enone analogues of curcumin for their ability to activate the Nrf2 pathway.
- To identify structural features that enhance Nrf2 activation and overcome curcumin's pharmacokinetic limitations.
Main Methods:
- Curcumin analogues with varying enone spacer lengths (3, 5, or 7 carbons) and aromatic ring substitutions were synthesized.
- An Nrf2 reporter assay was employed to screen and quantify the activation potential of these analogues.
- Dose-response studies were conducted to determine EC50 values and the extent of Nrf2 activation.
Main Results:
- Nrf2 activators were identified across all synthesized analogue groups, with many exhibiting greater potency than curcumin.
- The length of the enone spacer and substituents on the aromatic rings significantly influenced both the sensitivity (EC50) and efficacy of Nrf2 activation.
- These findings suggest diverse mechanisms underlying Nrf2 activation by the enone analogues.
Conclusions:
- Novel curcumin enone analogues represent a promising class of compounds for activating the Nrf2 pathway.
- Structural modifications can significantly enhance Nrf2 activation, potentially leading to more effective therapeutics for Nrf2-mediated conditions.
- Further investigation into these analogues may yield new treatments for chronic inflammatory and oxidative stress-related diseases.
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