Antioxidant protection by β-selenoamines against thioacetamide-induced oxidative stress and hepatotoxicity in mice

Difference in the Mechanism of Iron Overload-Enhanced Acute Hepatotoxicity Induced by Thioacetamide and Carbon Tetrachloride in Rats

Iron overload has been recognized as a risk factor for liver disease; however, little is known about its pathological role in the modification of liver injury. The purpose of this study is to investigate the influence of iron overload on liver injury induced by two hepatotoxicants with different pathogenesis in rats. Rats were fed a control (Cont), 0.8% high-iron (0.8% Fe), or 1% high-iron diet (1% Fe) for 4 weeks and were then administered with saline, thioacetamide (TAA), or carbon tetrachloride (CCl4). Hepatic and systemic iron overload were seen in the 0.8% and 1% Fe groups. Twenty-four hours after administration, hepatocellular necrosis induced by TAA and hepatocellular necrosis, degeneration, and vacuolation induced by CCl4, as well as serum transaminase values, were exacerbated in the 0.8% and 1% Fe groups compared to the Cont group. On the other hand, microvesicular vacuolation induced by CCl4 was decreased in 0.8% and 1% Fe groups. Hepatocellular DNA damage was increased by iron overload in both models, whereas a synergistic effect of oxidative stress by excess iron and hepatotoxicant was only present in the CCl4 model. The data showed that dietary iron overload exacerbates TAA- and CCl4-induced acute liver injury with different mechanisms.

SIRT1/Nrf2/NF-κB Signaling Mediates Anti-Inflammatory and Anti-Apoptotic Activities of Oleanolic Acid in a Mouse Model of Acute Hepatorenal Damage

Background and objectives: Oleanolic acid (OA) is a penta-cyclic triterpene with diverse bioactivities such as anticarcinogenic, antiviral, antimicrobial, hepatoprotective, anti-atherosclerotic, hypolipidemic, and gastroprotective. However, its effects on hepatorenal damage remain unclear. The protective activity of OA, separated from Viscum schimperi (Loranthaceae), against TAA (thioacetamide)-produced acute hepatic and renal damage was explored. Materials and Methods: Mice were treated with OA for 7 days before TAA (200 mg/kg, i.p.). Serum indices of hepatorenal injury, pathological lesions, molecular biological indexes, and inflammatory/apoptotic genes were estimated. Results: The tissues of both organs were greatly affected by the TAA injection. That was evident through increased serum markers of hepato-renal injury as well as remarkable histopathological lesions. TAA-induced injury was associated with oxidative and inflammatory responses in both organs as there was an elevation of oxidative stress parameters (4-HNE (4-hydroxy-nonenal), MDA (malondialdehyde), NOx (nitric oxide)), decline of antioxidants (reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (TAC)), and an increase in the gene expression/level of inflammatory mediators (interleukins (1β&6)). The inflammatory response was linked to a significant activation of NF-κB (nuclear-factor kappa-B)/TNF-α (tumor-necrosis factor-alpha) signaling. The inflammatory response in both organs was accompanied by apoptotic changes, including a rise in the gene expression and level of apoptotic parameters (caspase-3 and Bax) along with a decline in Bcl-2 (anti-apoptotic parameter) gene expression and level. These pathogenic events were found to be closely related to the suppression of the antioxidant signaling pathway, Nrf2 (nuclear-factor erythroid 2-related factor-2)/SIRT1 (sirtuin-1)/HO-1 (heme-oxygenase 1). On the other hand, OA significantly ameliorated TAA-induced injury in both organs. On the other hand, OA counterpoised the inflammatory response as it ameliorated NF-κB/TNF-α signaling and cytokine release. OA enhanced Nrf2/SIRT1/HO-1 signaling and counteracted apoptotic damage. Conclusions: OA showed anti-inflammation and antiapoptotic capacities that effectively suppressed TAA-induced acute hepatorenal damage.

Decarboxylative ring-opening of 2-oxazolidinones: a facile and modular synthesis of β-chalcogen amines

We report herein the synthesis of primary and secondary β-chalcogen amines through the regioselective ring-opening reaction of non-activated 2-oxazolidinones promoted by in situ generated chalcogenolate anions. The developed one-step protocol enabled the preparation of β-selenoamines, β-telluroamines and β-thioamines with appreciable structural diversity and in yields of up to 95%.

Crm1-Dependent Nuclear Export of Bach1 is Involved in the Protective Effect of Hyperoside on Oxidative Damage in Hepatocytes and CCl4-induced Acute Liver Injury

Background

Nrf2-Bach1 antioxidant signaling pathway is considered as one of the most important mechanisms of cellular resistance to oxidative injury. The effect of hyperoside (Hyp) on the expression and distribution of Bach1, the relationship of Hyp's antioxidative effect and the influence of Bach1 remains unclear.

Purpose

The aim of this study was to investigate the role and mechanisms of Bach1 in the protective effect of Hyp on oxidative liver injury.

Methods

The protective effect of Hyp on oxidative stress injury was observed in vivo and in vitro. Next, the influence of Hyp on Bach1 expression and distribution, and competitive combination of Nrf2-Bach1 with ARE in H₂O₂-induced L02 cell was studied by Western blot, RT-PCR, immunofluorescence and CHIP assay. Finally, the expressions of Crm1, ERK and p38 and their roles on Hyp mediated nuclear export of Bach1 were investigated by Western blot.

Results

Hyp ameliorated the pathological damage, reduced the liver index, AST, ALT and MDA activities, and increased SOD and GSH levels in the CCl₄-induced acute liver injury mouse model. Hyp attenuated H₂O₂-induced oxidative stress injury in L02 cells. Hyp promoted the early rapid redistribution of Bach1 from nucleus to cytoplasm. CHIP analyses demonstrated that Hyp enhanced the levels of Nrf2-ARE complex, and weakened the levels of Bach1-ARE complex within three hours. In addition, Hyp enhanced transport protein Crm1 expression and ERK1/2 activity. And LMB, a Crm1 inhibitor, attenuated the effect of Hyp on Bach1 nuclear export and anti-oxidation. U0126, an ERK1/2 inhibitor, reduced the effect of Hyp on Crm1 expression and the Bach1 redistribution.

Conclusion

The hepatoprotective mechanism of Hyp was related to improve Bach1 nuclear export depending on ERK1/2-Crm1 to upregulate the level of Nrf2 binding to ARE.

Dimethyl fumarate protects thioacetamide-induced liver damage in rats: Studies on Nrf2, NLRP3, and NF-κB

The present study was designed to investigate the hepatoprotective potential of dimethyl fumarate (DMF) against thioacetamide (TAA)-induced liver damage. Wistar rats were treated with DMF (12.5, 25, and 50 mg/kg/day, orally) and TAA (200 mg/kg intraperitoneally, every third day) for 6 consecutive weeks. TAA exposure significantly reduced body weight, increased liver weight and index, and intervention with DMF did not ameliorate these parameters. DMF treatment significantly restored TAA-induced increase in the levels of aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transferase, total bilirubin, uric acid, malondialdehyde, reduced glutathione, and histopathological findings such as inflammatory cell infiltration, deposition of collagen, necrosis, and bridging fibrosis. DMF treatment significantly ameliorated TAA-induced hepatic stellate cell activation, increase in inflammatory cascade markers (NACHT, LRR, and PYD domains-containing protein 3; NLRP3, apoptosis-associated speck like protein containing a caspase recruitment domain; ASC, caspase-1, nuclear factor-kappa B; NF-κB, interleukin-6), fibrogenic makers (α-smooth muscle actin; ɑ-SMA, transforming growth factor; TGF-β1, fibronectin, collagen 1) and antioxidant markers (nuclear factor (erythroid-derived 2)-like factor 2; Nrf2, superoxide dismutase-1; SOD-1, catalase). The present findings concluded that DMF protects against TAA-induced hepatic damage mediated through the downregulation of inflammatory cascades and upregulation of antioxidant status.