Butin

The cytoprotective effect of butin against oxidative stress is mediated by the up-regulation of manganese superoxide dismutase expression through a PI3K/Akt/Nrf2-dependent pathway.[Pubmed: 22253095]

J Cell Biochem. 2012 Jun;113(6):1987-97.

Butin (7,3',4'-trihydroxydihydroflavone), a flavonoid with antioxidant activity, was recently reported to protect cells against H2O2-induced apoptosis, oxidative DNA damage and oxidative mitochondrial dysfunction. The objective of the present study was to elucidate the mechanism by which Butin protects mitochondria.
METHODS AND RESULTS:
The antioxidant function of manganese superoxide dismutase (Mn SOD) is important in preventing oxidative stress. While exposure to H2O2 reduced the expression of Mn SOD in Chinese hamster lung fibroblast (V79-4), the addition of Butin restored Mn SOD expression at both the mRNA and protein levels, resulting in increased Mn SOD activity. The transcription factor NF-E2-related factor 2 (Nrf2) regulates Mn SOD gene expression by binding to the antioxidant responsive element (ARE). Butin enhanced the nuclear translocation and ARE-binding activity of Nrf2, which was decreased by H2O2. The siRNA-mediated knockdown of Nrf2 attenuated Butin-induced Mn SOD expression and activity. Further, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB, Akt) contributed to the ARE-driven Mn SOD expression. Butin activated PI3K/Akt and exposure to either LY294002 (a PI3K inhibitor), Akt inhibitor IV (an Akt-specific inhibitor), or Akt siRNA suppressed the Butin-induced activation of Nrf2, resulting in decreased Mn SOD expression and activity. Finally, the cytoprotective effect of Butin against H2O2-induced cell damage was suppressed by the siRNA-mediated knockdown of Mn SOD.
CONCLUSIONS:
These studies demonstrate that Butin attenuates oxidative stress by activating Nrf2-mediated Mn SOD induction via the PI3K/Akt signaling pathway.

Butin reduces oxidative stress-induced mitochondrial dysfunction via scavenging of reactive oxygen species.[Pubmed: 20060874]

Food Chem Toxicol. 2010 Mar;48(3):922-7.

This study investigated the cytoprotective effect of Butin, a flavonoid, on hydrogen peroxide (H(2)O(2))-induced mitochondrial dysfunction.
METHODS AND RESULTS:
Electron spin resonance (ESR) spectrometry revealed Butin's significant scavenging effects on superoxide radicals and hydroxyl radicals. When H(2)O(2) was used to induce an increase in mitochondrial reactive oxygen species (ROS) in Chinese hamster lung fibroblast (V79-4) cells, Butin treatment decreased high level of ROS. Butin also attenuated intracellular Ca(2+) levels that have been induced by H(2)O(2). Furthermore, Butin recovered ATP levels and succinate dehydrogenase activity that had been decreased by H(2)O(2) treatment.
CONCLUSIONS:
We conclude these results suggest Butin decreased mitochondrial ROS accumulation, balanced intracellular Ca(2+) levels, and improved mitochondrial energy production, thus recovering mitochondrial function.

Butin decreases oxidative stress-induced 8-hydroxy-2'-deoxyguanosine levels via activation of oxoguanine glycosylase 1.[Pubmed: 19631197]

Chem Biol Interact. 2009 Oct 30;181(3):338-42.

In response to oxidative DNA base damage, oxoguanine glycosylase 1 (OGG1), in a base-excision repair (BER) pathway in mammals, plays a vital role in the repair of 8-hydroxy-2'-deoxyguanosine (8-OHdG), which is a reliable marker of reactive oxygen species (ROS)-induced DNA base modification and contributes to the pathologic process of cancer.Recently, we have shown that Butin (7,3',4'-trihydroxydihydroflavone) protects cells against hydrogen peroxide (H2O2)-induced damage of cellular components including DNA.
METHODS AND RESULTS:
In the present study, we examined the possible protective effect of Butin on oxidative stress-induced DNA base modification, especially 8-OHdG. Hydrogen peroxide significantly increased the level of 8-OHdG, which was detected by 8-OHdG ELISA and confocal microscopy, but Butin decreased this level. Suppression of 8-OHdG formation by Butin was related to the enhanced mRNA and protein expression of OGG1, which was detected by RT-PCR and Western blot analysis. Butin also increased the transcriptional activity of OGG1, which was suppressed by H2O2 treatment; this transcriptional activity was detected by OGG1 promoter luciferase assay. Butin enhanced the expression of phosphorylated Akt (active form of Akt), a regulator of OGG1, which was decreased by H2O2 treatment.
CONCLUSIONS:
A PI3K-specific inhibitor, LY294002, abolished the phosphorylated Akt and OGG1 expressions induced by Butin, suggesting that OGG1 induction by Butin involves the PI3K/Akt pathway.

Butin (7,3',4'-trihydroxydihydroflavone) reduces oxidative stress-induced cell death via inhibition of the mitochondria-dependent apoptotic pathway.[Pubmed: 21747713]

Inhibitory effect of Rhus verniciflua Stokes extract on human aromatase activity; butin is its major bioactive component.[Pubmed: 24630560]

Bioorg Med Chem Lett. 2014 Apr 1;24(7):1730-3.

Rhus verniciflua Stokes has been used as a traditional herbal medicine in Asia. In this study, the effect of R. verniciflua extract on human aromatase (cytochrome P450 19, CYP19) activity was investigated to elucidate the mechanism for the effect of R. verniciflua extract on androgen hormone levels.
METHODS AND RESULTS:
Androstenedione was used as a substrate and incubated with R. verniciflua extract in cDNA-expressed CYP19 supersomes in the presence of NADPH, and estrone formation was measured using liquid chromatography-tandem mass spectrometry. R. verniciflua extract was assessed at concentrations of 10-1000 μg/mL. The resulting data showed that R. verniciflua extract inhibited CYP19-mediated estrone formation in a concentration-dependent manner with an IC50 value of 136 μg/mL. Subsequently, polyphenolic compounds from R. verniciflua extract were tested to identify the ingredients responsible for the aromatase inhibitory effects by R. verniciflua extract. As a result, Butin showed aromatase inhibitory effect in a concentration-dependent manner with an IC50 value of 9.6 μM, whereas the inhibition by other compounds was negligible.
CONCLUSIONS:
These results suggest that R. verniciflua extract could modulate androgen hormone levels via the inhibition of CYP19 activity and Butin is a major ingredient responsible for this activity.

Int J Mol Sci. 2011;12(6):3871-87.

Recently, we demonstrated that Butin (7,3',4'-trihydroxydihydroflavone) protected cells against hydrogen peroxide (H(2)O(2))-induced apoptosis by: (1) scavenging reactive oxygen species (ROS), activating antioxidant enzymes such superoxide dismutase and catalase; (2) decreasing oxidative stress-induced 8-hydroxy-2'-deoxyguanosine levels via activation of oxoguanine glycosylase 1, and (3), reducing oxidative stress-induced mitochondrial dysfunction. The objective of this study was to determine the cytoprotective effects of Butin on oxidative stress-induced mitochondria-dependent apoptosis, and possible mechanisms involved.
METHODS AND RESULTS:
Butin significantly reduced H(2)O(2)-induced loss of mitochondrial membrane potential as determined by confocal image analysis and flow cytometry, alterations in Bcl-2 family proteins such as decrease in Bcl-2 expression and increase in Bax and phospho Bcl-2 expression, release of cytochrome c from mitochondria into the cytosol and activation of caspases 9 and 3. Furthermore, the anti-apoptotic effect of Butin was exerted via inhibition of mitogen-activated protein kinase kinase-4, c-Jun NH(2)-terminal kinase (JNK) and activator protein-1 cascades induced by H(2)O(2) treatment. Finally, Butin exhibited protective effects against H(2)O(2)-induced apoptosis, as demonstrated by decreased apoptotic bodies, sub-G(1) hypodiploid cells and DNA fragmentation.
CONCLUSIONS:
Taken together, the protective effects of Butin against H(2)O(2)-induced apoptosis were exerted via blockade of membrane potential depolarization, inhibition of the JNK pathway and mitochondria-involved caspase-dependent apoptotic pathway.