The Cytoprotective Effects of E-α-(4-Methoxyphenyl)-2’,3,4,4'-Tetramethoxychalcone (E-α-p-OMe-C6H4-TMC)—A Novel and Non-Cytotoxic HO-1 Inducer

Abstract

Cell protection against different noxious stimuli like oxidative stress or chemical toxins plays a central role in the treatment of many diseases. The inducible heme oxygenase isoform, heme oxygenase-1 (HO-1), is known to protect cells against a variety of harmful conditions including apoptosis. Because a number of medium strong electrophiles from a series of α-X-substituted 2’,3,4,4’-tetramethoxychalcones (α-X-TMCs, X = H, F, Cl, Br, I, CN, Me, p-NO2-C6H4, Ph, p-OMe-C6H4, NO2, CF3, COOEt, COOH) had proven to activate Nrf2 resulting in HO-1 induction and inhibit NF-κB downstream target genes, their protective effect against staurosporine induced apoptosis and reactive oxygen species (ROS) production was investigated. RAW264.7 macrophages treated with 19 different chalcones (15 α-X-TMCs, chalcone, 2’-hydroxychalcone, calythropsin and 2’-hydroxy-3,4,4’-trimethoxychalcone) prior to staurosporine treatment were analyzed for apoptosis and ROS production, as well as HO-1 protein expression and enzyme activity. Additionally, Nrf2 and NF-κB activity was assessed. We found that amongst all tested chalcones only E-α-(4-methoxyphenyl)-2’,3,4,4'-tetramethoxychalcone (E-α-p-OMe-C6H4-TMC) demonstrated a distinct, statistically significant antiapoptotic effect in a dose dependent manner, showing no toxic effects, while its double bond isomer Z-α-p-OMe-C6H4-TMC displayed no significant activity. Also, E-α-p-OMe-C6H4-TMC induced HO-1 protein expression and increased HO-1 activity, whilst inhibition of HO-1 by SnPP-IX abolished its antiapoptotic effect. The only weakly electrophilic chalcone E-α-p-OMe-C6H4-TMC reduced the staurosporine triggered formation of ROS, while inducing the translocation of Nrf2 into the nucleus. Furthermore, staurosporine induced NF-κB activity was attenuated following E-α-p-OMe-C6H4-TMC treatment. Overall, E-α-p-OMe-C6H4-TMC demonstrated its effective cytoprotective potential via a non-toxic induction of HO-1 in RAW264.7 macrophages. The observed cytoprotective effect may partly be related to both, the activation of the Nrf2- and inhibition of the NF-κB pathway.

Isolation of Bioactive Compounds from Calicotome villosa Stems

“…The efficacy of these compounds strongly depends on the variation of the functions present in the structure. However, the synthetic derivatives of calythropsin exhibited more cytotoxicity than the calythropsin itself [ 17 , 51 , 52 , 53 , 54 , 55 ].…”

The Keap1/Nrf2-ARE Pathway as a Pharmacological Target for Chalcones

“…Kaufmann et al demonstrated that among a series of α-X-substituted 2′,3,4,4′-tetramethoxychalcones (α-X-TMCs, X = H, F, Cl, Br, I, CN, Me, p-NO 2 -C 6 H 4 , Ph, p-OMe-C 6 H 4 , NO 2 , CF 3 , COOEt, COOH), able to activate the Nrf2/HO-1 pathway and inhibit NF-κB downstream target genes, only E-α-(4-methoxyphenyl)-2′,3,4,4′-tetramethoxychalcone (E-α-p-OMe-C 6 H 4 -TMC) ( 30 ) showed a significant cytoprotective effect against staurosporine-induced toxicity in RAW264.7 cells [ 57 ]. In this regard, the cytoprotective effect of 30 may be partly related to both the non-toxic activation and inhibition of the Nrf2/HO-1 and NF-κB pathways, respectively.…”

The role of modulation of antioxidant enzyme systems in the treatment of neurodegenerative diseases

“…Synthetic chalcones 3a and 3b at 10 mM were non-toxic and upregulated g-Glutamylcysteine Ligase Catalytic Subunit (GCLC) and haeme oxygenase-1 (HO-1) up to 3-and 25-folds, respectively, and attenuated H 2 O 2 -induced apoptosis of in vitro 150 . E-a-(4-methoxyphenyl)-2 0 ,3,4,4 0 -tetramethoxychalcone 4 at 30 mM caused translocation of Nrf2 into nucleus, potently induced HO-1 and downregulated NFkB activity with no observed toxicity at higher concentrations 151 . The high electrophilicity of traditional Nrf2-activators poses the risk of ''off-target'' effects due to their ability to react with the cysteines of other proteins.…”

“…Both DMF and its primary metabolite, monomethyl fumarate, significantly protected neuronal and astrocyte cultures against H 2 O 2 -induced toxicity in an Nrf2-dependent manner 147,150 . In two HD mice models, the treatment with DMF preserved the motor function and the morphology of neurons in the striatum and the motor cortex 151 . Carbon monoxide (CO), the product of HO-1 metabolism, mediates potent anti-inflammatory and anti-apoptotic effects 152,153 .…”