Protective effects of diallyl disulfide on carbon tetrachloride-induced hepatotoxicity through activation of Nrf2

Peripheral serum iTRAQ-based proteomic characteristics of carbon tetrachloride-induced acute liver injury in Macaca fascicularis

Carbon tetrachloride (CCl4) is a potent chemical compound that can induce liver cells necrosis. The purpose of this study was to evaluate the hepatic toxicity of CCl4 exposure in Macaca fascicularis to explore the liver toxicity mechanism using a proteomic approach. One animal (no.F6) was intoxicated by oral gavage with 15 % CCl4 solution (10 mL/kg, dissolved in edible peanut oil), and was sacrificed at 48 h after CCl4 administration. Another blank control animal (no.F4) was sacrificed at the same time. The liver cells of the blank control animal showed normal hepatocyte morphology. However, the hepatocytes at 48 h time point after CCl4 administration showed necrosis and vacuolation histopathologically. The animal No.F7∼F12 and no.M7∼M12 were administrated by gavage with 15 % CCl4 solution (10 mL/kg, dissolved in edible peanut oil). Blood samples were collected before gavage administration, and served as the 0 h blank control samples. Then, blood samples were collected at 2 h, 48 h, 72 h and 168 h after CCl4 exposure, and served as the test samples. Routine biochemistry and immunical parameters were performed using biochemistry analyzer for all serum. Then the serum from male and female animals at 0 h, 2 h, 48 h, and 72 h was mixed, respectively. The peripheral serum proteins at 0 h, 2 h, 48 h, and 72 h were extracted, then the proteins were enzymatically hydrolyzed and the peptides were isotopic labeled by isobaric tags for relative and absolute quantification (iTRAQ). Finally, the UniProt Protein Sequence Library of Macaca fascicularis was queried to identify and compare the differential proteins between different time points. The results showed that, as traditional biomarkers of liver injury, alanine aminotransferases (ALT) and aspartate aminotransferases (AST) showed a typical time-effect curve. Compared with 0 h, there were totally 55, 323, and 158 differential proteins (P value <0.05, Ratio fold >1.5, FDR<0.05) at 2 h, 48 h and 72 h, respectively. GO enrichment analysis of differentially expressed proteins only at 48 h involved 3 cellular components (P adjust value <0.05), and differential proteins at other time points had no significant enrichment. Furthermore, KEGG enrichment analysis showed that the toxicity effect of CCl4 at different time points after administration was mediated through 22 pathways such as biosynthesis of antibiotics, carbon metabolism, biosynthesis of amino acids, peroxisome, cysteine and methionine metabolism, arginine biosynthesis, and complement and coagulation cascades (P adjust value <0.05). Among them, the counts of signaling pathway involved biosynthesis of antibiotics, carbon metabolism and biosynthesis of amino acids were more than 10 and the three pathways may play a greater role in toxicity progress after administration of CCl4. PPI network analysis showed that there were 3, 52, and 13 nodes in the interaction of differential proteins at 2 h, 48 h, and 72 h, respectively. In conclusion, many differential proteins in peripheral blood were detected after CCl4 administration, and the GO and KEGG enrichment analysis showed the toxicological mechanisms of CCl4-induced liver injury and potential protection reaction mechanism for CCl4 detoxication may be related with multi biological processes, signaling pathway and targets.

Diallyl disulfide downregulating RhoGDI2 induces differentiation and inhibit invasion via the Rac1/Pak1/LIMK1 pathway in human leukemia HL-60 cells

Leukemia is a type of disease in which hematopoietic stem cells proliferate clonally at the genetic level. We discovered previously by high-resolution mass spectrometry that diallyl disulfide (DADS), which is one of the effective ingredients of garlic, reduces the performance of RhoGDI2 from APL HL-60 cells. Although RhoGDI2 is oversubscribed in several cancer categories, the effect of RhoGDI2 in HL-60 cells has remained unexplained. We aimed to investigate the influence of RhoGDI2 on DADS-induced differentiation of HL-60 cells to elucidate the association among the effect of inhibition or over-expression of RhoGDI2 with HL-60 cell polarization, migration and invasion, which is important for establishing a novel generation of inducers to elicit leukemia cell polarization. Co-transfection with RhoGDI2-targeted miRNAs apparently decreases the malignant biological behavior of cells and upregulates cytopenias in DADS-treated HL-60 cell lines, which increases CD11b and decreases CD33 and mRNA levels of Rac1, PAK1 and LIMK1. Meanwhile, we generated HL-60 cell lines with high-expressing RhoGDI2. The proliferation, migration and invasion capacity of such cells were significantly increased by the treated with DADS, while the reduction capacity of the cells was decreased. There was a reduction in CD11b and an increase in CD33 production, as well as an increase in the mRNA levels of Rac1, PAK1 and LIMK1. It also confirmed that inhibition of RhoGDI2 attenuates the EMT cascade via the Rac1/Pak1/LIMK1 pathway, thereby inhibiting the malignant biological behavior of HL-60 cells. Thus, we considered that inhibition of RhoGDI2 expression might be a new therapeutic direction for the treatment of human promyelocytic leukemia. The anti-cancer property of DADS against HL-60 leukemia cells might be regulated by RhoGDI2 through the Rac1-Pak1-LIMK1 pathway, which provides new evidence for DADS as a clinical anti-cancer medicine.

Diallyl disulfide prevents 1,3-dichloro-2-propanol-induced hepatotoxicity through mitogen-activated protein kinases signaling

We investigated whether diallyl disulfide (DADS) has protective effects against 1,3-dichloro-2-propanol (1,3-DCP)-induced hepatotoxicity and oxidative damage in rats and HepG2 cells. DADS was administered to rats once daily for 7 days at doses of 30 and 60 mg/kg/day. One hour after the final DADS treatment, the rats were administered 90 mg/kg 1,3-DCP to induce acute hepatotoxicity. DADS treatment significantly suppressed the increase in serum aminotransferase levels induced by 1,3-DCP administration, and reduced histopathological alterations in the liver. DADS treatment reduced 1-3-DCP-induced apoptotic changes in the liver, as revealed by terminal deoxynucleotidyl transferase dUTP nick end labeling staining and immunohistochemistry for caspase-3. DADS treatment competitively inhibited or reduced cytochrome p450 2E1 (CYP2E1) expression, which is involved in the metabolic activation of 1,3-DCP, and enhanced antioxidant properties. Furthermore, DADS treatment inhibited phosphorylation of mitogen-activated protein kinases (MAPKs) and apoptotic signaling. In in vitro experiments, MAPKs inhibitors reduced the expression of Bax/Bcl-2/Caspase 3 signaling, which effects were more significant in co-treated cells with DADS and MAPKs inhibitors. In conclusion, the protective effect of DADS against 1,3-DCP-induced hepatotoxicity may be related to blocking the metabolic activation of 1,3-DCP by suppressing CYP2E1 expression, inducing antioxidant enzyme activity, and reducing apoptotic activity by inhibiting phosphorylation of MAPKs.

Biological Functions of Diallyl Disulfide, a Garlic-Derived Natural Organic Sulfur Compound

Garlic is widely accepted as a functional food and an excellent source of pharmacologically active ingredients. Diallyl disulfide (DADS), a major bioactive component of garlic, has several beneficial biological functions, including anti-inflammatory, antioxidant, antimicrobial, cardiovascular protective, neuroprotective, and anticancer activities. This review systematically evaluated the biological functions of DADS and discussed the underlying molecular mechanisms of these functions. We hope that this review provides guidance and insight into the current literature and enables future research and the development of DADS for intervention and treatment of multiple diseases.

Targeting Nrf2/Keap1 signaling pathway by bioactive natural agents: Possible therapeutic strategy to combat liver disease

BACKGROUND

Nuclear factor erythroid 2-related factor (Nrf2), a stress-activated transcription factor, has been documented to induce a defense mechanism against oxidative stress damage, and growing evidence considers this signaling pathway a key pharmacological target for the treatment of liver diseases.

PURPOSE

The present review highlights the role of phytochemical compounds in activating Nrf2 and mitigate toxicant-induced stress on liver injury.

METHODS

A comprehensive search of published articles was carried out to focus on original publications related to Nrf2 activators against liver disease using various literature databases, including the scientific Databases of Science Direct, Web of Science, Pubmed, Google, EMBASE, and Scientific Information (SID).

RESULTS

Nrf2 activators exhibited promising effects in resisting a variety of liver diseases induced by different toxicants in preclinical experiments and in vitro studies by regulating cell proliferation and apoptosis as well as an antioxidant defense mechanism. We found that the phytochemical compounds, such as curcumin, naringenin, sulforaphane, diallyl disulfide, mangiferin, oleanolic acid, umbelliferone, daphnetin, quercetin, isorhamnetin-3-O-galactoside, hesperidin, diammonium glycyrrhizinate, corilagin, shikonin, farrerol, and chenpi, had the potential to improve the Nrf2-ARE signaling thereby combat hepatotoxicity.

CONCLUSION

Nrf2 activators may offer a novel potential strategy for the prevention and treatment of liver diseases. More extensive studies are essential to identify the underlying mechanisms and establish future therapeutic potentials of these signaling modulators. Further clinical trials are warranted to determine the safety and effectiveness of Nrf2 activators for hepatopathy.

Diallyl disulfide and diallyl trisulfide in garlic as novel therapeutic agents to overcome drug resistance in breast cancer

Breast cancer is one of the leading causes of cancer-related deaths in women worldwide. It is a cancer that originates from the mammary ducts and involves mutations in multiple genes. Recently, the treatment of breast cancer has become increasingly challenging owing to the increase in tumor heterogeneity and aggressiveness, which gives rise to therapeutic resistance. Epidemiological, population-based, and hospital-based case-control studies have demonstrated an association between high intake of certain Allium vegetables and a reduced risk in the development of breast cancer. Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are the main allyl sulfur compounds present in garlic, and are known to exhibit anticancer activity as they interfere with breast cancer cell proliferation, tumor metastasis, and angiogenesis. The present review highlights multidrug resistance mechanisms and their signaling pathways in breast cancer. This review discusses the potential anticancer activities of DADS and DATS, with emphasis on drug resistance in triple-negative breast cancer (TNBC). Understanding the anticancer activities of DADS and DATS provides insights into their potential in targeting drug resistance mechanisms of TNBC, especially in clinical studies.

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The review describes the causes of drug resistance in TNBC.

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The effects of DADS and DATS on drug resistance mechanisms in TNBC are presented.

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The impacts of DADS and DATS on metastasis of TNBC are discussed.

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Antitumor immune activities of DADS and DATS against TNBC are illustrated.

Ameliorative Role of Diallyl Disulfide Against Glycerol-induced Nephrotoxicity in Rats

Introduction:

This study investigated the role of diallyl disulfide (DADS) against glycerol-induced nephrotoxicity in rats. Moreover, the role of peroxisome proliferator activated receptor-γ (PPAR-γ) in DADS-mediated renoprotection has been explored.

Materials and Methods:

Male Wistar albino rats were challenged with glycerol (50% w/v, 8 mL/kg intramuscular) to induce nephrotoxicity. Kidney injury was quantified by measuring serum creatinine, creatinine clearance, urea, potassium, fractional excretion of sodium, and microproteinuria in rats. Renal oxidative stress was measured in terms of thiobarbituric acid reactive substances, superoxide anion generation, and reduced glutathione levels. Hematoxylin–eosin (H&E) and periodic acid Schiff staining of renal samples was done to show histological changes. Glycerol-induced muscle damage was quantified by assaying creatine kinase (CK) levels in rat serum.

Results:

Administration of glycerol resulted in muscle damage as reflected by significant rise in CK levels in rats. Glycerol intoxication led kidney damage was reflected by significant change in renal biochemical parameters, renal oxidative stress and histological changes in rat kidneys. Administration of DADS attenuated glycerol-induced renal damage. Notably, pretreatment with bisphenol A diglycidyl ether, a PPAR-γ antagonist, abolished DADS renoprotection in rats.

Conclusion:

We conclude that DADS affords protection against glycerol-induced renal damage in rats. Moreover, PPAR-γ plays a key role in DADS-mediated renoprotective effect.

Diallyl disulfide ameliorates methotrexate-induced nephropathy in rats: Molecular studies and network pharmacology analysis

Methotrexate (MTX) is a promising chemotherapeutic agent. Its medical use is limited by induced nephropathy. Our study was designed to explore the reno-protective effect of diallyl disulfide (DADS), an organosulfur compound of garlic oil, on MTX-induced nephropathy. Adult rats were randomly divided into 4 groups; normal control, DADS (50 mg kg^-1  day^-1 , p.o.), MTX (20 mg/kg, i.p.) and DADS+MTX. DADS significantly decreased serum creatinine, urea, uric acid, and albumin levels with an improvement of final body weight. Additionally, DADS markedly attenuated MTX-induced elevations in renal MDA and NO 2 - contents with an increase in GSH content and SOD activity. Mechanistically, DADS effectively down-regulated mRNA expression level of renal p38 and NF-κB. Additionally, DADS positively regulated the NRF2 gene with a remarkable inhibition of Keap-1 gene. Furthermore, DADS up-regulated BCL2 protein and remarkably suppressed the expression of both BAX and caspase-3 proteins. Overall, DADS has favorable renal protection against MTX-induced nephropathy via modulation of Keap-1/NRF2, p38/NF-κB, and BCL2/BAX/caspase-3 signaling. PRACTICAL APPLICATIONS: Diallyl disulfide is one of the organosulfur compounds of garlic oil. Our study demonstrated that DADS substantially alleviated the decline of kidney function and renal injury induced by MTX. The antioxidative, anti-inflammatory, and anti-apoptotic properties may constitute an important part of its therapeutic applications via regulation of p38/NF-κB, Keap-1/NRF2, and BCL2/BAX/caspase-3 signaling pathways. Therefore, DADS could be a potential therapeutic adjunct in cancer chemotherapy to decrease the associated side effects of MTX. It should be further explored clinically as a protective agent for MTX-treated cancer patients.

Diallyl disulfide improves lipid metabolism by inhibiting PCSK9 expression and increasing LDL uptake via PI3K/Akt-SREBP2 pathway in HepG2 cells

BACKGROUND AND AIM

Diallyl disulfide (DADS), a volatile sulfide extracted from garlic, has been suggested as a chemical of anti-atherosclerotic drugs, while its molecular mechanism for this benefit has not fully been understood. The aim of the present study was to investigate the effects of DADS on lipid metabolism and its potential mechanisms in HepG2 cells induced by lipopolysaccharides (LPS).

METHODS AND RESULTS

HepG2 cells were treated with LPS with or without different concentrations of DADS (0, 20, 40, 80, 160 μg/ml) for 24 h. The cell activity was detected by CCK8, and Dil-LDL uptake assay was used to examine the LDL uptake. Real-time PCR and Western blot were used to detect the expression of LDLR, PCSK9 SREBP2 and HMGCR. In addition, we examined the effect of the combination of DADS with atorvastatin on PCSK9 expression. The results showed that LPS significantly increased PCSK9 and SREBP2 expressions in a dose-dependent manner in HepG2 cells. DADS attenuated PCSK9, SREBP2 and HMGCR expressions and up-regulated the expression of LDLR. Moreover, DADS reversed the expressions of PCSK9, SREBP2, HMGCR and LDLR induced by LPS and DADS could promote the LDL uptake in HepG2 cells. Furthermore, DADS decreased the expression of PCSK9 by activating the PI3K/Akt-SREBP2 signal pathway. Notably, DADS could reduce PCSK9 expression induced by atorvastatin in HepG2 cells.

CONCLUSION

DADS could significantly attenuated PCSK9 expression in a dose-dependent manner induced by LPS and increased the LDLR expression in HepG2 cells, which was associated with the activation of PI3K/Akt-SREBP2 signaling pathway.

Nephroprotective activity of Annona Squamosa leaves against paracetamol-induced nephrotoxicity in rats: in vitro and in vivo experiments

Background

Paracetamol (PCM), being extensively adapted analgesic and anti-inflammatory drug all over the world, beyond therapeutic dosages, the oxidative stress-involved nephrotoxicity has been evidenced. However, herbal plants are the windfall for the humankind providing solution for most of the wellness breakdowns. Annona squamosa (AS) is one of such plants with enormous therapeutic and nutraceutical potencies. The main aspiration of the current investigation is to evaluate the nephroprotective ability of ethanolic extract of Annona squamosa (EEAS) leaves against paracetamol-induced nephrotoxicity using in vitro human embryonic kidney (HEK)-293 cells and in vivo experiments in Wistar rats through biochemical parameters, oxidative parameters, and histopathological findings.

Results

When HEK-293 cells were incubated with PCM, an increased cell death associated with alterations in the morphology of normal cells was observed. At variable concentrations, HEK-293 cells co-treated with PCM and EEAS extracts gave a significant improvement in cell growth on comparing with PCM treatment showing cytoprotective feature of EEAS with an IC50 28.75 μg/mL. In vivo nephroprotective property was assessed from the amount of blood urea nitrogen (BUN) along with creatinine and uric acid which were reduced (P < 0.001) within serum and compact levels of glutathione, catalase, and superoxide dismutase which were termed as GSH, CAT, and SOD, respectively, were increased (P < 0.001) in kidney tissue homogenate in the treated groups than the PCM alone group. Results were additionally supported by histopathological observations.

Conclusion

The results exhibited that EEAS has impending benefits against PCM-induced nephrotoxicity through in vitro and in vivo experiments.

Antioxidant and Anti-Inflammatory Effects of Diallyl Disulfide on Hepatotoxicity Induced by Cyclophosphamide in Rats

Diallyl disulfide (DADS) is a garlic-derived organo-sulfur compound. This study was carried out to investigate the protective potential, antioxidant, and anti-inflammatory effects of this compound against cyclophosphamide (CP)-induced hepatotoxicity in rats. A single intraperitoneal dose of CP (200 mg/kg) resulted in a significant disturbance in hepatic function and oxidative stress, as well as inflammatory biomarkers. In addition, histopathological examination showed distinct changes and increased expression of proliferating cell nuclear antigen in hepatocytes. On the other hand, daily oral preadministration of DADS (200 mg/kg) for 10 days before the CP dose effectively attenuated the hepatotoxicity caused by CP administration as confirmed by significant amelioration of the aforementioned parameters in rat’s liver. It could be concluded that administration of DADS can diminish CP-induced hepatotoxicity through concurrent upregulation of antioxidant and anti-inflammatory responses that denote its possible potential clinical application against side effects of the CP drug.

The Nrf2-Keap1 pathway: A secret weapon against pesticide persecution in Drosophila Kc cells

Nrf2-Keap1 pathway defends organisms against the detrimental effects of oxidative stress, and play pivotal roles in preventing xenobiotic-related toxicity. We designed experiments to explore and verify its role and function under deltamethrin (DM) stress. In experiments, DM was selected as the inducer, and Drosophila Kc cells were treated as the objects. The result showed the oxidative stress of cells proliferated in a very short time after DM treatment, reaching the maximum after one hour of treatment. The experimental data showed Nrf2 could be up-regulated and activated by DM which were manifested by the increase of Nrf2 mRNA, Nrf2 protein in the nucleus and the expression of detoxification enzyme genes. We further tested the activity of all groups, and found the survival rate of cells was basically proportional to the expression of Nrf2. Based on the above experimental results, Keap1 overexpression (K+), Nrf2 overexpression (N+) or interference (N-) cells were used to verified the relationship between Nrf2, cell survival and detoxification enzymes expression. We found the cell survival rate of N+ group was significantly higher than that of other groups and the expression of detoxification enzymes were increased compared to the control group. These results demonstrated that Nrf2 is related to cell detoxification and associated with the tolerance to DM. Our evidence suggested Nrf2 is a potential therapeutic target for oxidative stress and a potential molecular target gene of resistance control.

S-1-propenylmercaptocysteine protects murine hepatocytes against oxidative stress via persulfidation of Keap1 and activation of Nrf2

The onion-derived metabolite, S-1-propenylmercaptocysteine (CySSPe), protects against oxidative stress and exhibits anti-inflammatory effects by modulating cellular redox homeostasis. We sought to establish whether CySSPe activates nuclear factor erythroid 2-related factor 2 (Nrf2) and whether activation of Nrf2 by CySSPe involves modification of the Kelch-like ECH-associated protein-1 (Keap1) to manifest these effects. We found that CySSPe stabilized Nrf2 protein and facilitated nuclear translocation to induce expression of antioxidant enzymes, including NQO1, HO-1, and GCL. Moreover, CySSPe attenuated tert-butyl hydroperoxide-induced cytotoxicity and dose-dependently inhibited reactive oxygen species production. Silencing experiments using Nrf2-siRNA confirmed that CySSPe conferred protection against oxidative stress by activating Nrf2. CySSPe enhanced cellular pool of reduced glutathione (GSH) and improved GSH:GSSG ratio. Pretreatment of cells with l-buthionine-S,R-sulfoximine (BSO) confirmed that CySSPe increases de novo synthesis of GSH by upregulating expression of the GSH-synthesizing enzyme GCL. Treatment of cells with CySSPe elevated hydrogen sulfide (H₂S) production. Inhibition of H₂S-synthesizing enzymes, cystathionine-gamma-lyase (CSE) and cystathionine-beta-synthase (CBS), by pretreating cells with propargylglycine (PAG) and oxyaminoacetic acid (AOAA) revealed that H₂S production was partially dependent on a CSE/CBS-catalyzed β-elimination reaction with CySSPe that likely produced 1-propenyl persulfide (RSSH). Depleting cells of their GSH pool by exposure to BSO and diethylmaleate attenuated H₂S production, suggesting a GSH-dependent formation of H₂S, likely via the reduction of RSSH by GSH. Finally, treatment of cells with CySSPe persulfidated Keap1, which may be the mechanism involved for the stabilization of Nrf2 by CySSPe. Taken together, our results showed that attenuation of oxidative stress by CySSPe is associated with its ability to produce H₂S or RSSH, which persulfidates Keap1 and activates Nrf2 signaling. This study provides insights on the potential of CySSPe as an onion-derived dietary agent that modulates redox homeostasis and combats oxidative stress.

Induction of Nrf2 pathway by Dendrobium nobile Lindl. alkaloids protects against carbon tetrachloride induced acute liver injury

Dendrobium nobile Lindl. alkaloids (DNLA), the active ingredients of Dendrobium, has been shown to possess anti-oxidative effects. The nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant signaling pathway plays a critical role in the cellular response to oxidative stress. Oxidative damage has been implicated in the mechanism of various hepatotoxins induced liver injury. The present study aimed to examine the protective effects of DNLA on CCl₄-induced acute liver injury, and to explore the role of the Nrf2 pathway in the protective action of DNLA. Wild-type (WT) and Nrf2-knockout (Nrf2^-/-) mice were administrated with DNLA (20 mg/kg/day, ig) for 7 days, and then challenged with CCl₄ (20 μL/kg, ip). In WT mice, DNLA reduced CCl₄ induced liver injury, as evidenced by the reduction in the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), attenuation of malondialdehyde (MDA) production, and improved ultrastructural morphology in hepatocytes. However, the protective effect was diminished in Nrf2^-/- mice, indicating an essential role of Nrf2 in DNLA-mediated protection over CCl₄ liver injury. Furthermore, it was found that DNLA enhanced Nrf2 expression and nuclear accumulation and increased the expression of Nrf2 regulated downstream proteins. These results demonstrate that DNLA protects mice from CCl₄ induced liver injury, probably through the activation of the Nrf2 signaling pathway.

Diallyl disulfide attenuates non‑alcoholic steatohepatitis by suppressing key regulators of lipid metabolism, lipid peroxidation and inflammation in mice

Non‑alcoholic steatohepatitis (NASH) is a common clinicopathological condition. Currently, the pathogenesis of NASH remains unknown, and no optimal therapy option currently exists. It has previously been demonstrated that diallyl disulfide (DADS) was capable of attenuating liver dysfunction, as DADS supplementation had a positive impact on liver regeneration, proliferation and oxidative damage. Thus, DADS could serve as a potential therapeutic agent that can protect against the effects of NASH. The present study aimed to evaluate the effect of DADS on NASH and to understand the associated underlying molecular mechanisms. A methionine‑ and choline‑deficient diet (MCD) and high‑fat diet (HFD) are the two common animal models that induce NASH. C57BL/6J mice were fed an MCD for 4 weeks, or an HFD for 20 weeks, in the present study. The mice were treated with or without DADS (20, 50 and 100 mg/kg) for 4 or 20 weeks. For the histopathological examination, hematoxylin and eosin staining, oil red O staining and immunohistochemical analyses were performed using the liver sections. Biochemical assays and ELISA were performed to measure the serum biochemical indicators of hepatic function and inflammatory indicators, respectively. Reverse transcription‑quantitative PCR, immunofluorescence and western blotting were used to detect expression levels of the genes involved in the molecular mechanisms underlying DADS protection. MCD or HFD induced the histological features of NASH in mice, including significant vacuolated hepatocytes, marked inflammatory cell infiltration and severe micro‑ and macro‑vesicular steatosis. Serum alanine transferase and aspartate aminotransferase levels, as well as the contents of liver triglyceride and total cholesterol, were significantly increased in these two models. DADS attenuated these histological and biochemical changes. DADS ameliorated hepatic steatosis by regulating sterol regulatory element‑binding transcription factor 1, apolipoprotein A1, cyclic AMP‑responsive element‑binding protein H and fibroblast growth factor 21. Furthermore, DADS was revealed to prevent lipotoxicity via peroxisome proliferator‑activated receptor α elevation and stearoyl‑coenzyme A desaturase 1 inhibition in HFD‑fed mice. In addition, DADS markedly inhibited lipid peroxidation by modulating malondialdehyde and superoxide dismutase, and it also decreased tumor necrosis factor‑α production, interleukin‑6 production and macrophage influx, as well as suppressing nuclear factor‑κB activation, indicating suppression of MCD‑induced hepatic inflammation. Taken together, the results have shown that DADS exerts beneficial effects on MCD‑ or HFD‑induced NASH by suppressing key regulators of lipid metabolism, lipid peroxidation and inflammation.

Ketoconazole pretreatment ameliorates carbon tetrachloride-induced acute liver injury in rats by suppressing inflammation and oxidative stress

Several studies have demonstrated the chemopreventive role of ketoconazole in animal models of liver injury. However, the underlying molecular mechanisms of this hepatoprotective effect are poorly understood. The present study assessed the potential of ketoconazole to enhance resistance to carbon tetrachloride-induced hepatotoxicity in vivo in a rat model. Ketoconazole pretreatment adult male rats were intraperitoneally injected with carbon tetrachloride for 24 hr and various hepatic parameters were analyzed. We observed decreased serum transaminases activity, reduced nuclear RelA/p65 expression, and suppressed production of pro-inflammatory cytokines in the liver tissue. Histopathological examination demonstrated ketoconazole pretreatment to extensively prevent liver injury. In addition, it significantly increased nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) protein expression, glutathione (GSH) to oxidized glutathione (GSSG) ratio, and antioxidant enzymes gene expression. These results suggest that ketoconazole pretreatment ameliorates carbon tetrachloride-induced acute liver injury in rats, signifying its anti-inflammatory and antioxidant functions.

Hydrogen Sulfide as a Novel Regulatory Factor in Liver Health and Disease

Hydrogen sulfide (H₂S), a colorless gas smelling of rotten egg, has long been recognized as a toxic gas and environment pollutant. However, increasing evidence suggests that H₂S acts as a novel gasotransmitter and plays important roles in a variety of physiological and pathological processes in mammals. H₂S is involved in many hepatic functions, including the regulation of oxidative stress, glucose and lipid metabolism, vasculature, mitochondrial function, differentiation, and circadian rhythm. In addition, H₂S contributes to the pathogenesis and treatment of a number of liver diseases, such as hepatic fibrosis, liver cirrhosis, liver cancer, hepatic ischemia/reperfusion injury, nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, hepatotoxicity, and acute liver failure. In this review, the biosynthesis and metabolism of H₂S in the liver are summarized and the role and mechanism of H₂S in liver health and disease are further discussed.

Alleviation of carbon tetrachloride-induced hepatocellular damage and oxidative stress with a leaf extract of Glyphae brevis (Tiliaceae)

Background Glyphae brevis leaf is reported in ethnomedicine as a treatment for hepatitis and jaundice; however, no studies have hitherto investigated the mechanistic basis of these claims. Methods A hepato-protective role of G. brevis hydromethanolic (GBH) leaf extract was established against carbon tetrachloride (CCl4)-induced hepatotoxicity. Twenty-four hours after a CCl4 challenge, rats were sacrificed and serum hematological indices, lipid profile, and biochemical parameters were determined. The antioxidant enzymes parameters (glutathione, catalase, and superoxide dismutase) and lipid peroxidation product (thiobarbituric reactive substances) levels in liver homogenates were evaluated. Changes in the liver cyto-architecture of different treatment groups were also investigated. Results The GBH extract produced no significant impact on weight and hematological indices. Intoxication with CCl4 significantly (p<0.001-0.05) increased total cholesterol (TC) and low-density lipoproteins (LDL) compared with control rats. Pretreatment with GBH leaf extract significantly reduced triglycerides, TC, and LDL to approaching control levels (p<0.001-0.05). The GBH leaf extract significantly alleviated CCl4-induced elevation of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and the CCl4-induced depression of total protein, and albumin. Liver antioxidant parameters were significantly increased in plant extract-treated rats, and this antagonized the pro-oxidant effect of CCl4. Histopathological studies also supported a hepato-protective effect of GBH. Collectively, the GBH leaf extract alleviated the CCl4-induced hepatotoxicity through improvement of innate antioxidant enzyme levels and lipid metabolism and stabilized the hepatocyte cyto-architecture of intoxicated rats. Conclusions This study establishes the ethnomedicinal role of G. brevis leaf in hepatitis and the mechanistic basis of hepato-protection against CCl4-induced hepatotoxicity.

Black Radish (Raphanus sativus L. var. niger) Extract Mediates Its Hepatoprotective Effect on Carbon Tetrachloride-Induced Hepatic Injury by Attenuating Oxidative Stress

Nonalcoholic fatty liver disease is a serious liver disorder associated with oxidative stress. Black radish (Raphanus sativus L. var. niger) extract (BRE) can lower the risk of this disease. The hepatoprotective effect of BRE containing 3-(E)-(methylthio)methylene-2-pyrrolidinethione was evaluated in human hepatocyte carcinoma (HepG2) cells and in rat livers with carbon tetrachloride (CCl₄)-induced hepatic injury. BRE was administered at 125, 250, 500, and 1000 μg/mL to the oleic acid-induced HepG2 cells. Male Sprague-Dawley rats were randomly divided into seven groups: the control group, BRE group, CCl₄ group, and BRE + CCl₄ group. BRE was administered orally at 125, 250, 500, and 1000 mg/kg/day once daily for 7 consecutive days, followed by a single oral treatment of 1.5 mL/kg CCl₄. Inhibition of lipid accumulation, serum markers of liver injury, histological evaluations, levels of oxidative stress related enzymatic and nonenzymatic antioxidants in HepG2 cells and liver tissue were investigated. The protein expression of main liver P450 isoenzymes such as cytochrome p450(CYP)2E1, the expression of nuclear factor erythroid 2-related factor-2(Nrf-2) and heme oxygenase-1(HO-1) were also studied. BRE has an inhibitory effect on lipid accumulation and caused acute hepatotoxicity manifested by increased levels of lipid peroxidation, serum alanine aminotransferase, and aspartate aminotransferase with corresponding histopathological changes and high levels of oxidative stress. BRE treatment significantly increased the level of CYP2E1, Nrf-2, and HO-1 in a dose-dependent manner. Besides, 3-(E)-(methylthio)methylene-2-pyrrolidinethione significantly increased radical-scavenging effects and the expression of Nrf-2 in oleic acid-treated HepG2 cells. These results suggest that BRE treatment reduces lipid accumulation in oleic acid-induced steatosis of HepG2 cells, and has a hepatoprotective effect against CCl₄-induced liver injury in rats, possibly through Nrf-2/HO-1-mediated antioxidant effects.

Hepatoprotective and antioxidant activities of Spondias mombin leaf and stem extracts against carbon tetrachloride-induced hepatotoxicity

Objective

Spondias mombin L. is a tree used in folk medicine in Nigeria for the treatment of hepatitis. This study was carried out to comparatively evaluate the hepatoprotective and antioxidant effects of S. mombin leaf and stem (SML and SMS) methanolic extracts in a rat model of carbon tetrachloride (CCl₄)-induced hepatotoxicity.

Methods

Forty-two rats were distributed into seven groups. Groups A and B received water; groups C and D received 500 and 1000 mg/kg SML extract, respectively; groups E and F received 500 and 1000 mg/kg SMS extract, respectively; and group G received 100 mg/kg silymarin. Water, the two extracts, and silymarin were administered daily by oral gavage for 7 days. Hepatotoxicity was induced in groups B to G by the administration of CCl₄ once on the seventh day. After 48 h, rats were sacrificed, and tissues and serum samples were examined for histological and biochemical indices of hepatotoxicity.

Results

Administration of CCl₄ resulted in liver injury with significant elevation in the hepatocellular injury markers alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TBIL), and conjugated bilirubin (CBIL), associated with a significant reduction in total circulatory protein. Pretreatment with SML and SMS extracts at both doses significantly ameliorated liver injury; lowered ALT, AST, ALP, TBIL, and CBIL levels; elevated cellular glutathione levels as well as catalase and superoxide dismutase activities; and decreased the levels of thiobarbituric acid reactive substances.

Conclusion

This study provides preliminary evidence supporting the potential therapeutic benefit of S. mombin in xenobiotic-induced hepatotoxicity.

Diallyl disulfide effect on the invasion and migration ability of HL-60 cells with a high expression of DJ-1 in the nucleus through the suppression of the Src signaling pathway

The present study examined the effect of diallyl disulfide (DADS) on the invasion and migration ability of HL-60 cells with a high expression of parkinsonism associated deglycase (DJ-1) in the nucleus (HHDN), and its molecular mechanism. A western blot assay was used to measure the effects of DADS and an Src inhibitor on the expression of DJ-1 and the Src signal pathway in HHDN. The effects of DADS and Src inhibitors on the invasion and migration ability of HHDN was detected using Transwell migration and invasion chamber experiments. The experiments were divided into three groups: A control group (HL-60 cells), an empty vector group and a high expression group (HHDN cells). Western blot assays revealed that the expression of DJ-1 in HHDN was inhibited in a time-dependent manner following treatment with DADS for 24, 48 and 72 h. Following DADS treatment, the expression of phosphorylated Src (p-Src) and phosphorylated Fak (p-Fak) were significantly decreased in all groups compared with the untreated groups, however the expression level of Src, Fak and integrin did not change significantly. Western blot analysis results revealed that following treatment with DADS and Src inhibitor, the expression levels of p-Src and p-Fak significantly decreased in all three groups compared with untreated groups, whereas the expression levels of Src, Fak and integrin did not change significantly. The expression of DJ-1 in HHND was inhibited in time-dependent manner following treatment with DADS and Src inhibitor for 24, 48 and 72 h. Transwell migration and invasion assay results revealed that DADS and Src inhibitors may suppress migration and invasion in leukemic cells, and a combination of the two treatments may result in more efficient suppression. DADS may downregulate DJ-1-mediated invasion and migration in leukemic cells through suppressing the Src-Fak-Integrin signaling pathway, and the Src inhibitor may enhance the antitumor effect of DADS.

Curcumin Attenuates on Carbon Tetrachloride-Induced Acute Liver Injury in Mice via Modulation of the Nrf2/HO-1 and TGF-β1/Smad3 Pathway

This study aimed to investigate the protective effect of curcumin against carbon tetrachloride (CCl₄)-induced acute liver injury in a mouse model, and to explain the underlying mechanism. Curcumin at doses of 50, 100 and 200 mg/kg/day were administered orally once daily for seven days prior to CCl₄ exposure. At 24 h, curcumin-attenuated CCl₄ induced elevated serum transaminase activities and histopathological damage in the mouse's liver. Curcumin pre-treatment at 50, 100 and 200 mg/kg significantly ameliorated CCl₄-induced oxidative stress, characterized by decreased malondialdehyde (MDA) formations, and increased superoxide dismutase (SOD), catalase (CAT) activities and glutathione (GSH) content, followed by a decrease in caspase-9 and -3 activities. Curcumin pre-treatment significantly decreased CCl₄-induced inflammation. Furthermore, curcumin pre-treatment significantly down-regulated the expression of TGF-β1 and Smad3 mRNAs (both p < 0.01), and up-regulated the expression of nuclear-factor erythroid 2-related factor 2 (Nrf2) and HO-1 mRNA (both p < 0.01) in the liver. Inhibition of HO-1 attenuated the protective effect of curcumin on CCl₄-induced acute liver injury. Given these outcomes, curcumin could protect against CCl₄-induced acute liver injury by inhibiting oxidative stress and inflammation, which may partly involve the activation of Nrf2/HO-1 and inhibition of TGF-β1/Smad3 pathways.

Diallyl disulphide inhibits apolipoprotein(a) expression in HepG2 cells through the MEK1-ERK1/2-ELK-1 pathway

Background

Lipoprotein(a) [LP(a)] is implicated as a common and independent risk factor for cardiovascular diseases. The therapeutic options currently available for reducing plasma LP(a) concentrations are limited. Diallyl disulphide (DADS), the main component of garlic, regulates lipid metabolism in hepatocytes and adipocytes through ERK1/2 signalling. This study aimed to assess the effect of DADS on apolipoprotein(a) [apo(a)] in HepG2 cells. We also determined the effects of DADS on apo(a) expression and secretion in HepG2 cells as well as the underlying mechanisms.

Methods

We examined the role of DADS on apo(a) expression in HepG2 cells by treating cell with different concentrations of DADS (10, 20, 40 and 80 μg/mL) for 24 h or treating cells with 40 μg/mL DADS for 0, 6, 12, 24 and 48 h. Then we used quantitative real-time PCR to analysis apo(a) mRNA levels, used Western blot to analysis apo(a) protein levels and used enzyme-linked immunosorbent assay to test apo(a) secreted levels. To farther determined the role of DADS, we applied Transfection of small interfering RNA to knockdown ELK-1levels and applied PD98059, a specific inhibitor of ERK1/2, to block ERK1/2 signal.

Results

The results show DADS inhibited apo(a) at both the mRNA and protein levels in HepG2 cells in a dose-dependent manner. DADS-mediated inhibition of apoa(a) expression in HepG2 cells was attenuated when the cells were cultured in medium containing PD98059 (ERK1/2 inhibitor) or were transfected with siRNAs against MEK1 or ELK-1. Overexpression of apo(a) yielded similar results.

Conclusions

This study reveals that DADS can downregulate apo(a) expression in a dose-dependent manner via the MEK-ERK12-ELK-1 pathway.

Naturally Occurring Nrf2 Activators: Potential in Treatment of Liver Injury

Oxidative stress plays a major role in acute and chronic liver injury. In hepatocytes, oxidative stress frequently triggers antioxidant response by activating nuclear erythroid 2-related factor 2 (Nrf2), a transcription factor, which upregulates various cytoprotective genes. Thus, Nrf2 is considered a potential therapeutic target to halt liver injury. Several studies indicate that activation of Nrf2 signaling pathway ameliorates liver injury. The hepatoprotective potential of naturally occurring compounds has been investigated in various models of liver injuries. In this review, we comprehensively appraise various phytochemicals that have been assessed for their potential to halt acute and chronic liver injury by enhancing the activation of Nrf2 and have the potential for use in humans.

Prophylaxis of Diallyl Disulfide on Skin Carcinogenic Model via p21-dependent Nrf2 stabilization

Cancer prevention through intake of biologically active natural products appears to be an accessible way to reduce the risk of cancer. Diallyl disulfide (DADS), a major garlic derivative, has exhibited potential role in cancer therapy. The study is aimed to evaluate the prophylactic effect of DADS in chemically induced mouse skin carcinogenesis and investigate the molecular targets mediated by DADS. Two-stage chemically induced carcinogenesis model by cutaneous application of DMBA and subsequent TPA was established to study the prophylactic effect of DADS. As a result, we observed that DADS dose-dependently attenuated skin tumor incidence and multiplicity in the model mice, which was related to the up-regulation of a bunch of antioxidant enzymes activities and the nuclear accumulation of Nrf2. Furthermore, we developed skin carcinogenesis in Nrf2 knockout mice which could reverse the activity of DADS. Finally, we uncovered the underlying mechanism that DADS promoted the endogenous interaction between p21 and Nrf2, which was critical for impairing the Keap1-mediated degradation of Nrf2. Based on the results, we concluded that DADS was a promising cancer chemoprevention agent and suggested a garlic-rich diet might be beneficial to reduce the cancer risk in our daily life.

Upregulation of miR-34a by diallyl disulfide suppresses invasion and induces apoptosis in SGC-7901 cells through inhibition of the PI3K/Akt signaling pathway

Diallyl disulfide (DADS) exerts anticarcinogenic activity in various types of cancer. However, the mechanism underlying its anticarcinogenic activity remains to be elucidated. The aim of the present study was to explore the mechanism of the anticarcinogenic activity of DADS in gastric cancer (GC). The expression levels of microRNA (miR)-34a in GC and normal tissues were measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The expression of miR-34a was also measured using RT-qPCR in SGC-7901 cells following treatment with DADS. In addition, the effect of DADS on the invasion capability of SGC-7901 cells was observed in the presence of miR-34a or anti-miR-34a using a Matrigel invasion assay. Furthermore, in identical conditions, the apoptosis of SGC-7901 cells was observed using flow cytometry. Finally, the present study investigated the effects of DADS and miR-34a on the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway in vitro. The level of miR-34a in GC tissues was reduced compared with that in adjacent normal tissues (P<0.05). Treatment with DADS upregulated miR-34a expression in SGC-7901 cells (P<0.05). In the Matrigel invasion assay, DADS inhibited the invasive capability of SGC-7901 cells (P<0.05 vs. control), which was improved by overexpression of miR-34a (P<0.01 vs. control) but reduced by downregulation of miR-34a (P<0.05 vs. DADS treatment group). Furthermore, DADS induced apoptosis of SGC-7901 cells (P<0.05 vs. control); and DADS and miR-34a synergistically enhanced apoptosis of SGC-7901 cells (P<0.01 vs. control). In addition, DADS and miR-34a inhibited the expression levels of phosphorylated (p)-PI3K and p-Akt (P<0.05 vs. control). By contrast, downregulation of miR-34a alleviated the decrease in p-PI3K and p-Akt expression induced by DADS (P<0.05 vs. DADS treatment group). Cell viability was reduced with increasing concentrations of DADS, however, DADS did not affect cell viability following inhibition of the PI3K/Akt signaling pathway. In conclusion, DADS suppresses invasion and induces apoptosis of SGC-7901 cells by upregulation of miR-34a, via inhibition of the PI3K-Akt signaling pathway.

Antioxidant and hepatoprotective effect of polyphenols from apple pomace extract via apoptosis inhibition and Nrf2 activation in mice

Industrial apple pomace, a biowaste generated during apple processing, is rich in cell wall polysaccharides and phenolics. These biologically active compounds are reported to be highly beneficial from the nutritional and health point of view. In the present study, the total phenolic content in the apple pomace aqueous extract (APE) was estimated and evaluated for its possible antioxidant and hepatoprotective efficacy in carbon tetrachloride (CCl₄)-induced liver injury mice model. The aqueous extract exhibited 2,2-diphenyl-2-picrylhydrazyl free radical scavenging activity in vitro. Under in vivo study, mice were treated with APE (200 mg and 400 mg/kg body weight) for 2 weeks prior to the administration of CCl₄ (30% v/v). The serum liver injury markers alanine transaminase, aspartate transaminase, and alkaline phosphatase were significantly lowered by APE in a dose-dependent manner. The levels of antioxidant parameters superoxide dismutase (SOD), reduced glutathione (redGSH), and lipid peroxidation were also improved by APE in liver homogenate. Histopathological studies revealed that APE treatment significantly lowered the CCl₄-induced necrotic changes in the liver. Furthermore, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end-labeling assay showed that CCl₄-induced apoptosis in the liver was significantly inhibited by APE in a dose-dependent manner. Immunohistochemistry results showed higher expression of nuclear erythroid 2-related factor 2 (Nrf2) in the liver of the APE-treated mice, a key regulator of antioxidative response. In conclusion, the results of the present study revealed the hepatoprotective efficacy of APE by inhibiting CCl₄-induced apoptosis, which is due to its antioxidant activity and the ability to induce Nrf2 protein expression.

Neohesperidin Dihydrochalcone versus CCl₄-Induced Hepatic Injury through Different Mechanisms: The Implication of Free Radical Scavenging and Nrf2 Activation

Neohesperidin dihydrochalcone (NHDC), a sweetener derived from citrus, belongs to the family of bycyclic flavonoids dihydrochalcones. NHDC has been reported to act against CCl4-induced hepatic injury, but its mechanism is still unclear. We first discovered that NHDC showed a strong ability to scavenge free radicals. In addition, NHDC induces the phase II antioxidant enzymes heme oxygenase 1 (HO-1) and NAD(P)H/quinone oxidoreductase 1 (NQO1) through the activation of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/antioxidant response element (ARE) signaling. Further assays demonstrated that NHDC induces accumulation of Nrf2 in the nucleus and augmented Nrf2-ARE binding activity. Moreover, NHDC inhibits the ubiquitination of Nrf2 and suggests the modification of Kelch-like ECH-associated protein 1 (Keap1) and the disruption of the Keap1/Nrf2 complex. c-Jun N-terminal kinase (JNK) and p38 but not extracellular signal-regulated protein kinase (ERK) phosphorylations were up-regulated by NHDC treatment. Taken together, NHDC showed its protective antioxidant effect against CCl4-induced oxidative damage via the direct free radical scavenging and indirect Nrf2/ARE signaling pathway.

DADS suppresses human esophageal xenograft tumors through RAF/MEK/ERK and mitochondria-dependent pathways

Diallyl disulfide (DADS) is a natural organosulfur compound isolated from garlic. DADS has various biological properties, including anticancer, antiangiogenic, and antioxidant effects. However, the anticancer mechanisms of DADS in human esophageal carcinoma have not been elucidated, especially in vivo. In this study, MTT assay showed that DADS significantly reduced cell viability in human esophageal carcinoma ECA109 cells, but was relatively less toxic in normal liver cells. The pro-apoptotic effect of DADS on ECA109 cells was detected by Annexin V-FITC/propidium iodide (PI) staining. Flow cytometry analysis showed that DADS promoted apoptosis in a dose-dependent manner and the apoptosis rate could be decreased by caspase-3 inhibitor Ac-DEVD-CHO. Xenograft study in nude mice showed that DADS treatment inhibited the growth of ECA109 tumor in both 20 and 40 mg/kg DADS groups without obvious side effects. DADS inhibited ECA109 tumor proliferation by down-regulating proliferation cell nuclear antigen (PCNA). DADS induced apoptosis by activating a mitochondria-dependent pathway with the executor of caspase-3, increasing p53 level and Bax/Bcl-2 ratio, and downregulating the RAF/MEK/ERK pathway in ECA109 xenograft tumosr. Based on studies in cell culture and animal models, the findings here indicate that DADS is an effective and safe anti-cancer agent for esophageal carcinoma.