Antioxidative and hepatoprotective effects of magnolol on acetaminophen-induced liver damage in rats

Phenelzine protects against acetaminophen induced apoptosis in HepG2 cells

Acetaminophen (APAP) overdosing is the most common cause of drug-induced liver failure. Despite extensive study, N-acetylcysteine is currently the only antidote utilized for treatment. The purpose of this study was to evaluate the effect and mechanisms of phenelzine, an FDA-approved antidepressant, on APAP-induced toxicity in HepG2 cells. The human liver hepatocellular cell line HepG2 was used to investigate APAP-induced cytotoxicity. The protective effects of phenelzine were determined by examining the cell viability, combination index calculation, Caspase 3/7 activation, Cytochrome c release, H2O2 levels, NO levels, GSH activity, PERK protein levels, and pathway enrichment analysis. Elevated H2O2 production and decreased glutathione (GSH) levels were indicators of APAP-induced oxidative stress. The combination index of 2.04 indicated that phenelzine had an antagonistic effect on APAP-induced toxicity. When compared to APAP alone, phenelzine treatment considerably reduced caspase 3/7 activation, cytochrome c release, and H2O2 generation. However, phenelzine had minimal effect on NO and GSH levels and did not alleviate ER stress. Pathway enrichment analysis revealed a potential connection between APAP toxicity and phenelzine metabolism. These findings suggested that phenelzine's protective effect against APAP-induced cytotoxicity could be attributed to the drug's capacity to reduce APAP-mediated apoptotic signaling.

A Comparative GC/MS Analysis of Citrus Essential Oils: Unveiling the Potential Benefits of Herb-Drug Interactions in Preventing Paracetamol-Induced Hepatotoxicity

Our study aimed to test the potential of Citrus oils in protecting against paracetamol (PAR)-induced hepatotoxicity. The essential oils of Pineapple sweet orange (OO), Murcott mandarin (MO), Red grapefruit (GO), and Oval kumquat (KO) were investigated using gas chromatography coupled with mass spectrometry (GC/MS). Twenty-seven compounds were identified, with monoterpene hydrocarbons being abundant class. d-Limonene had the highest percentage (92.98 %, 92.82 %, 89.75 %, and 94.46 % in OO, MO, GO, and KO, respectively). Hierarchical cluster analysis (HCA) and principal components analysis (PCA) revealed that octanal, linalool, germacrene D, and d-limonene were the principal discriminatory metabolites that segregated the samples into three distinct clusters. In vitro antioxidant capacities were ranged from 1.2-12.27, 1.79-5.91, and 235.05-585.28 μM Trolox eq/mg oil for 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic (ABTS), ferric-reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC), respectively. In vivo, citrus oils exhibited a significant reduction in alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and nitric oxide (NO). Additionally, there was an increase in glutathione reductase (GSH), and the liver architecture was nearly normal. Molecular docking revealed that d-limonene exhibited a good inhibitory interaction with cytochrome P450 (CYP450) isoforms 1A2, 3A4, and 2E1, with binding energies of -6.17, -4.51, and -5.61 kcal/mol, respectively.

Calycosin inhibits hepatocyte apoptosis in acute liver failure by suppressing the TLR4/NF-κB pathway: An in vitro study

BACKGROUND

Acute liver failure (ALF) is a serious liver disease that is difficult to treat owing to its unclear pathogenesis. This study aimed to investigate the roles and molecular mechanisms of calycosin (CA) in ALF.

METHODS

In this study, the roles and mechanism of CA in ALF were explored using an in vitro lipopolysaccharide (LPS)-induced ALF cell model. Additionally, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide assay was used to assess the effect of CA on the activity of LPS-induced L02 human liver epithelial cells, and flow cytometry was used to detect apoptosis in L02 cells. Expression levels of apoptosis-related genes, Bax and Bcl-2, were measured using reverse transcription-quantitative polymerase chain reaction and Western blot analysis. Expression levels of inflammatory factors in LPS-induced L02 cells were measured using an enzyme-linked immunosorbent assay. Additionally, the effect of CA on ALF was inhibited via transfection of a toll-like receptor 4 (TLR4)-plasmid to elucidate the relationship between CA and TLR4/nuclear factor (NF)-κB signaling pathway in ALF.

RESULTS

CA had no toxic effects on L02 cells, but enhanced the activity of LPS-induced L02 cells in a dose-dependent manner. Apoptosis and inflammatory factor release was increased in ALF, activating the TLR4/NF-κB signaling pathway. However, CA treatment inhibited the apoptosis and release of inflammatory factors. Further mechanistic studies revealed that the upregulation of TLR4 expression reversed the alleviating effects of CA on inflammation and apoptosis in LPS-induced L02 cells.

CONCLUSION

CA alleviates inflammatory damage in LPS-induced L02 cells by inhibiting the TLR4/NF-κB pathway and may be a promising therapeutic agent for ALF treatment.

Magnolol induces cytotoxic autophagy in glioma by inhibiting PI3K/AKT/mTOR signaling

Glioma is difficult-to-treat because of its infiltrative nature and the presence of the blood-brain barrier. Temozolomide is the only FDA-approved drug for its management. Therefore, finding a novel chemotherapeutic agent for glioma is of utmost importance. Magnolol, a neolignan, has been known for its apoptotic role in glioma. In this work, we have explored a novel anti-glioma mechanism of Magnolol associated with its role in autophagy modulation. We found increased expression levels of Beclin-1, Atg5-Atg12, and LC3-II and lower p62 expression in Magnolol-treated glioma cells. PI3K/AKT/mTOR pathway proteins were also downregulated in Magnolol-treated glioma cells. Next, we treated the glioma cells with Insulin, a stimulator of PI3K/AKT/mTOR signaling, to confirm that Magnolol induced autophagy by inhibiting this pathway. Insulin reversed the effect on Magnolol-mediated autophagy induction. We also established the same in in vivo glioma model where Magnolol showed an anti-glioma effect by inducing autophagy. To confirm the cytotoxic effect of Magnolol-induced autophagy, we used Chloroquine, a late-stage autophagy inhibitor. Chloroquine efficiently reversed the anti-glioma effects of Magnolol both in vitro and in vivo. Our study revealed the cytotoxic effect of Magnolol-induced autophagy in glioma, which was not previously reported. Additionally, Magnolol showed no toxicity in non-cancerous cell lines as well as rat organs. Thus, we concluded that Magnolol is an excellent candidate for developing new therapeutic strategies for glioma management.

Magnolol as a Protective Antioxidant Alleviates Rotenone-Induced Oxidative Stress and Liver Damage through MAPK/mTOR/Nrf2 in Broilers

This study aimed to investigate the protective effects and molecular mechanism of magnolol supplementation on rotenone-induced oxidative stress in broilers. Two hundred and eighty-eight old male AA broilers were randomly divided into four groups: the CON group: basic diet with sunflower oil injection; the ROT group: basic diet with 24 mg/kg BW rotenone; the MAG + ROT group: basic diet with 300 mg/kg magnolol and rotenone injection; and the MAG group: basic diet with 300 mg/kg magnolol and sunflower oil injection. At 21−27 days of age, the broilers in each group were intraperitoneally injected with rotenone (24 mg/kg BW) or the same volume of sunflower oil. The results showed that magnolol reversed the decrease in ADG post-injection and FBW via rotenone induction. Compared to the ROT group, MAG + ROT group enhanced the average daily gain post injection (p < 0.05). Magnolol supplement could improve the activity and mRNA expression of rotenone-suppressed antioxidant enzymes such as GSH and GSH-PX (p < 0.05). Similarly, the MDA content as an oxidative damage marker was significantly reduced after magnolol addition (p < 0.05). The hepatocyte apoptosis and the mRNA expression of apoptosis-related signaling pathway in the ROT group increased, but magnolol supplementation inhibited rotenone-induced apoptosis through the Nrf2 signaling pathway. Through RNA transcriptome analysis, there were 277 differential genes expressions (DEGs) among the CON group with ROT group, and 748 DEGs were found between the ROT group and the MAG + ROT group. KEGG pathway enrichment found that magnolol relieved rotenone-induced energy metabolism disorder and oxidative damage through signaling pathways such as MAPK and mTOR. In conclusion, magnolol attenuates rotenone-induced hepatic injury and oxidative stress of broilers, presumably by restoring hepatic antioxidant function via the MAPK/mTOR/Nrf2 signaling pathway.

Acetaminophen induced hepatotoxicity: An overview of the promising protective effects of natural products and herbal formulations

BACKGROUND

The liver plays an important role in regulating the metabolic processes and is the most frequently targeted organ by toxic chemicals. Acetaminophen (APAP) is a well-known anti-allergic, anti-pyretic, non-steroidal anti-inflammatory drug (NSAID), which upon overdose leads to hepatotoxicity, the major adverse event of this over-the-counter drug.

PURPOSE

APAP overdose induced acute liver injury is the second most common cause that often requires liver transplantation worldwide, for which N-acetyl cysteine is the only synthetic drug clinically approved as an antidote. So, it was felt that there is a need for the novel therapeutic approach for the treatment of liver diseases with less adverse effects. This review provides detailed analysis of the different plant extracts; phytochemicals and herbal formulations for the amelioration of APAP-induced liver injury.

METHOD

The data was collected using different online resources including PubMed, ScienceDirect, Google Scholar, Springer, and Web of Science using keywords given below.

RESULTS

Over the past decades various reports have revealed that plant-based approaches may be a better treatment choice for the APAP-induced hepatotoxicity in pre-clinical experimental conditions. Moreover, herbal compounds provide several advantages over the synthetic drugs with fewer side effects, easy availability and less cost for the treatment of life-threatening diseases.

CONCLUSION

The current review summarizes the hepatoprotective effects and therapeutic mechanisms of various plant extracts, active phytoconstituents and herbal formulations with potential application against APAP induced hepatotoxicity as the numbers of hepatoprotective natural products are more without clinical relativity. Further, pre-clinical pharmacological research will contribute to the designing of natural products as medicines with encouraging prospects for clinical application.

Magnolol additive improves growth performance of Linwu ducklings by modulating antioxidative status

Magnolol is a bioactive polyphenolic compound commonly found in Magnolia officinalis. The aim of this study is to clarify the contribution of the magnolol additive on the growth performance of Linwu ducklings aging from 7 to 28 d, comparing to the effects of antibiotic additive (colistin sulphate). A total of 325, 7-d-old ducklings were assigned to 5 groups. Each group had 5 cages with 13 ducklings in each cage. The ducklings in different groups were fed with diets supplemented with 0, 100, 200 and 300 mg/kg magnolol additive (MA) (Control, MA100, MA200 and MA300) and 30 mg/kg colistin sulphate (CS30) for 3 weeks, respectively. Parameters regarding to the growth performance, intestinal mucosal morphology, serum biochemical indices, antioxidant and peroxide biomarkers and the expression levels of antioxidant-related genes were evaluated by one way ANOVA analysis. The results showed that 30 mg/kg colistin sulphate, 200 and 300 mg/kg magnolol additive improved the average final weight (P = 0.045), average daily body weight gain (P = 0.038) and feed/gain ratios (P = 0.001) compared to the control group. 200 and 300 mg/kg magnolol additive significantly increased the villus height/crypt depth ratio of ileum, compared to the control and CS30 groups (P = 0.001). Increased serum level of glucose (P = 0.011) and total protein (P = 0.006) were found in MA200 or MA300 group. In addition, comparing to the control and CS30 groups, MA200 or MA300 significantly increased the levels of superoxide dismutase (P = 0.038), glutathione peroxidase (P = 0.048) and reduced glutathione (P = 0.039) in serum. Moreover, the serum and hepatic levels of 8-hydroxy-2'-deoxyguanosine (P = 0.043 and 0.007, respectively) were lower in all MA groups compared to those of the control and CS30 group. The hepatic mRNA expression levels of superoxide dismutase-1, catalase and nuclear factor erythroid-2-related factor 2/erythroid-derived CNC-homology factor were also increased significantly in MA200 and MA300 groups (P < 0.05). Taken together, these data demonstrated that MA was an effective feed additive enhancing the growth performance of Linwu ducklings at 7 to 28 d by improving the antioxidant and intestinal mucosal status. It suggested that MA could be a potential ingredient to replace the colistin sulphate in diets.

Mechanism of drug-induced liver injury and hepatoprotective effects of natural drugs

Drug-induced liver injury (DILI) is a common adverse drug reaction (ADR) and a serious threat to health that affects disease treatments. At present, no targeted clinical drugs are available for DILI. Traditional natural medicines have been widely used as health products. Some natural medicines exert specific hepatoprotective effects, with few side effects and significant clinical efficacy. Thus, natural medicines may be a promising direction for DILI treatment. In this review, we summarize the current knowledge, common drugs and mechanisms of DILI, as well as the clinical trials of natural drugs and their bioactive components in anticipation of the future development of potential hepatoprotective drugs.

The rich pharmacological activities of Magnolia officinalis and secondary effects based on significant intestinal contributions

ETHNOPHARMACOLOGICAL RELEVANCE

Magnolia officinalis Cortex (M. officinalis) is a traditional herbal drug widely used in Asian countries. Depending on its multiple biological activities, M. officinalis is used to regulate gastrointestinal (GI) motility, relieve cough and asthma, prevent cardiovascular and cerebrovascular diseases, and treat depression and anxiety.

AIM OF THE REVIEW

We aimed to review the abundant form of pharmacodynamics activity and potential mechanisms of action of M. officinalis and the characteristics of the internal processes of the main components. The potential mechanisms of local and distance actions of M. officinalis based on GI tract was provided, and it was used to reveal the interconnections between traditional use, phytochemistry, and pharmacology.

MATERIALS AND METHODS

Published literatures about M. officinalis and its main components were collected from several scientific databases, including PubMed, Elsevier, ScienceDirect, Google Scholar and Web of Science etc. RESULTS: M. officinalis was shown multiple effects including effects on digestive system, respiratory system, central system, which is consistent with traditional applications, as well as some other activities such as cardiovascular system, anticancer, anti-inflammatory and antioxidant effects and so on. The mechanisms of these activities are abundant. Its chief ingredients such as magnolol and honokiol can be metabolized into active metabolites in vivo, which can increase water solubility and bioavailability and exert pharmacological activity in the whole body. In the GI tract, M. officinalis and its main ingredient can regulate GI hormones and substance metabolism, protect the intestinal barrier and affect the gut microbiota (GM). These actions are effective to improve local discomfort and some distal symptoms such as depression, asthma, or metabolic disorders.

CONCLUSIONS

Although M. officinalis has rich pharmacological effects, the GI tract makes great contributions to it. The GI tract is not only an important place for absorption and metabolism but also a key site to help M. officinalis exert local and distal efficacy. Pharmacodynamical studies on the efficacies of distal tissues based on the contributions of the GI tract hold great potential for understanding the benefits of M. officinalis and providing new ideas for the treatment of important diseases.

Anti-Inflammatory and Antioxidant Properties of Carvacrol and Magnolol, in Periodontal Disease and Diabetes Mellitus

Periodontal disease and diabetes mellitus are two pathologies that are extremely widespread worldwide and share the feature of chronic inflammation. Carvacrol is a phenolic monoterpenoid, produced by a variety of herbs, the most well-known of which is Origanum vulgare. Magnolol is a traditional polyphenolic compound isolated from the stem bark of Magnolia officinalis, mainly used in Chinese medicine. The purpose of this paper is to review the therapeutic properties of these bioactive compounds, in the treatment of periodontitis and diabetes. Based on our search strategy we conducted a literature search in the PubMed and Google Scholar databases to identify studies. A total of one hundred eighty-four papers were included in the current review. The results show that carvacrol and magnolol have anti-inflammatory, antioxidant, antimicrobial, anti-osteoclastic, and anti-diabetic properties that benefit both pathologies. Knowledge of the multiple activities of carvacrol and magnolol can assist with the development of new treatment strategies, and the design of clinical animal and human trials will maximize the potential benefits of these extracts in subjects suffering from periodontitis or diabetes.

Anti-Neuroinflammatory Potential of Polyphenols by Inhibiting NF-κB to Halt Alzheimer's Disease

Alzheimer's disease (AD) is an irrevocable chronic brain disorder featured by neuronal loss, microglial accumulation, and progressive cognitive impairment. The proper pathophysiology of this life-threatening disorder is not completely understood and no exact remedies have been found yet. Over the last few decades, research on AD has mainly highlighted pathomechanisms linked to a couple of the major pathological hallmarks, including extracellular senile plaques made of amyloid-β (Aβ) peptides, and intracellular neurofibrillary tangles (NFTs) made of tau proteins. Aβ can induce apoptosis, trigger an inflammatory response, and inhibit the synaptic plasticity of the hippocampus, which ultimately contributes to reducing cognitive functions and memory impairment. Recently, a third disease hallmark, the neuroinflammatory reaction that is mediated by cerebral innate immune cells, has become a spotlight in the current research area, assured by pre-clinical, clinical, and genetic investigations. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a cytokine producer, is significantly associated with physiological inflammatory proceedings and thus shows a promising candidate for inflammation- based AD therapy. Recent data reveal that phytochemicals, mainly polyphenol compounds, exhibit potential neuroprotective functions and these may be considered as a vital resource for discovering several drug candidates against AD. Interestingly, phytochemicals can easily interfere with the signaling pathway of NF-κB. This review represents the anti-neuroinflammatory potential of polyphenols as inhibitors of NF-κB to combat AD pathogenesis.

Emodin in Rheum undulatum inhibits oxidative stress in the liver via AMPK with Hippo/Yap signalling pathway

Context: Emodin is a compound in Rheum undulatum Linne (Polygonaceae) that has been reported to exert anti-inflammatory, antibacterial, and antiallergic effects.Objective: Oxidative stress is a causative agent of liver inflammation that may lead to fibrosis and hepato-carcinoma. In this study, we investigated the antioxidant effects of emodin and its mechanism.Materials and methods: We used the hepatocyte stimulated by arachidonic acid (AA) + iron cotreatment and the C57B/6 mice orally injected with acetaminophen (APAP, 500 mg/kg, 6 h), as assessed by immunoblot and next generation sequencing (NGS). Emodin was pre-treated in hepatocyte (3 ∼ 30 μM) for 1 h before AA + iron, and in mice (10 and 30 m/kg, P.O.) for 3 days before APAP.Results: In vitro, emodin treatment inhibited the cell death induced by AA + iron maximally at a dose of 10 μM (EC₅₀ > 3 μM). In addition, emodin attenuated the decrease of anti-apoptotic proteins, and restored mitochondria membrane potential as mediated by the liver kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) pathway. LKB1 mediated AMPK activation was verified using the LKB1 deficient cell line, HeLa. Emodin (10 μM; after 10 min) also induced the phosphorylation of Yes-associated protein 1 (YAP1), the main downstream target of the Hippo signalling pathway that mediated oxidative stress or the ROS-initiated signalling pathway. In vivo, the oral treatment of emodin (10 and 30 m/kg, 3 days) decreased APAP-induced hepatic damage, as indicated by decreases in antioxidant genes as well as tissue damage.Conclusion: Our results show that emodin inhibits oxidative liver injury via the AMPK/YAP mediated pathway.

Herbal Therapy for the Treatment of Acetaminophen-Associated Liver Injury: Recent Advances and Future Perspectives

Acetaminophen (APAP) overdose is the leading cause of drug-induced liver injury worldwide, and mitochondrial oxidative stress is considered the major event responsible for APAP-associated liver injury (ALI). Despite the identification of N-acetyl cysteine, a reactive oxygen species scavenger that is regarded as an effective clinical treatment, therapeutic effectiveness remains limited due to rapid disease progression and diagnosis at a late phase, which leads to the need to explore various therapeutic approaches. Since the early 1990s, a number of natural products and herbs have been found to have hepatoprotective effects against APAP-induced hepatotoxicity in terms of acute liver failure prevention and therapeutic amelioration of ALI. In this review, we summarize the hepatoprotective effects and mechanisms of medicinal plants, including herbs and fruit extracts, along with future perspectives that may provide guidance to improve the current status of herbal therapy against ALI.

Apoptosis induction and ERK/NF-κB inactivation are associated with magnolol-inhibited tumor progression in hepatocellular carcinoma in vivo

Although hepatitis B and/or hepatitis C virus were recognized as major risk factor for the development of hepatocellular carcinoma (HCC), certain occupational, environmental, and lifestyle factors also play key roles in HCC tumorigenesis. Moreover, in molecular signaling route, extracellular signal-regulated kinase (ERK)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling was found to be overexpressed and linked to poor prognosis in HCC. Thus, to identify possible nature compound that can suppress ERK/NF-κB may be benefit to HCC patient. Magnolol, a natural compound derived from herbal plant Magnolia officinalis, has been recognized as a liver protection and antitumor reagent. However, whether magnolol-inhibited HCC progression correlates with disruption of ERK/NF-κB signaling is remained unclear. In this studies, we performed SK-Hep1/luc2 HCC bearing animal model to investigate the anticancer efficacy and mechanism of magnolol on tumor progression. Tumor size and tumor growth rate were dramatically suppressed after treatment of magnolol. In addition, expression of phospho-ERK (p-ERK), NF-κB p65 (Ser536), and tumor progression-associated proteins, such as matrix metallopeptidase 9 (MMP-9), vascular endothelial growth factor (VEGF), X-linked inhibitor of apoptosis protein (XIAP), and CyclinD1 were all significantly decreased by magnolol. Most important, major extrinsic and intrinsic apoptosis signaling factors, including active caspase-8 and caspase-9 were both enhanced by magnolol. This study indicated that apoptosis induction through extrinsic/intrinsic pathways and blockage of ERK/NF-κB activation were associated with magnolol-inhibited tumor progression in HCC in vivo.

Magnolol Prevents Acute Alcoholic Liver Damage by Activating PI3K/Nrf2/PPARγ and Inhibiting NLRP3 Signaling Pathway

Alcoholic liver damage (ALD) is a toxic liver damage caused by excessive drinking. Oxidative stress is one of the most crucial pathogenic factors leading to ALD. Magnolol is one of the main active constituents of traditional Chinese medicine Magnolia officinalis, which has been reported to possess many pharmacological effects including anti-inflammatory, anti-oxidant, and anti-tumor. However, the effects of magnolol on ALD remain unclear. In this study, we firstly evaluated the protective effects of magnolol on ALD, and then tried to clarify the mechanism underlying the pharmacological activities. AST, ALT, GSH-Px, and SOD were detected by respective kits. Histopathological changes of liver tissue were analyzed by H&E staining. The activities of PI3K, Nrf2, and NLRP3 signaling pathways activation were detected by western blotting analysis. It was showed that alcohol-induced ALT and AST levels were significantly reduced by magnolol, but the antioxidant enzymes of GSH-Px and SOD levels were significantly increased. Magnolol attenuated alcohol-induced pathologic damage such as decreasing hepatic cord swelling, hepatocyte necrosis, and inflammatory cell infiltration. Furthermore, it was found that magnolol inhibited oxidative stress through up-regulating the activities of HO-1, Nrf2, and PPARγ and the phosphorylation of PI3K and AKT. And magnolol also decreased inflammatory response by inhibiting the activation of NLRP3inflammasome, caspase-1, and caspase-3 signaling pathway. Above results showed that magnolol could prevent alcoholic liver damage, and the underlying mechanism was through activating PI3K/Nrf2/PPARγ signaling pathways as well as inhibiting NLRP3 inflammasome, which also suggested magnolol might be used as a potential drug for ALD.

Magnolol additive improves carcass and meat quality of Linwu ducks by modulating antioxidative status

Magnolol rich in Magnolia officinalis is a bioactive polyphenolic compound. The aim of this study was to clarify the effects of magnolol additive (MA) on carcass and meat quality, biochemical characteristics and antioxidative capacity of Linwu ducks, by comparing it to that of antibiotic additive (colistin sulphate, CS). A total of 275 49-d-old ducks were randomly assigned to 5 groups with 5 cages of 11 ducks each and fed by the diets supplemented with 0, 100, 200 and 300 mg of MA/kg and 30 mg of CS/kg for 3 weeks, respectively. The results revealed that MA administration not only increased dressed percentage (calculated as a percentage of live weight), percentage of breast muscle, leg muscle and lean meat (calculated as a percentage of eviscerated weight), but also remarkably increased a*_{45 min} and pH_{45 min} of leg muscle. Moreover, MA administration decreased the percentage of abdominal fat (calculated as a percentage of eviscerated weight), 45-min cooking loss, water loss rate of leg muscle, 45-min cooking loss and drip loss of breast muscle at 24 hr and 48 hr. Furthermore, MA administration enhanced the activities of superoxide dismutase and catalase in serum or liver, serum total antioxidant capacity and hepatic reduced glutathione concentration significantly, compared with the basal diet or CS group (p < .05). On the other hand, triglyceride, total cholesterol, aspartate aminotransferase, malondialdehyde, protein carbonyl and 8-hydroxy-2'-deoxyguanosine contents in serum and liver were significantly increased in Linwu ducks fed with CS, compared with MA groups (p < .05). Taken together, these data demonstrated that magnolol could effectively improve the carcass and meat quality of Linwu ducks by regulating the in vivo antioxidant status and would be a potential candidate to replace antibiotic.

Apoptosis perturbations and expression of regulatory inflammatory factors in cisplatin-depleted rat livers under l-arginine protection

Hepatic injury is one of the most common complications associated with cisplatin (CIS) use. Recently, liver protection lines are being discovered to stop the hepatic cell death due to inflammatory and apoptotic perturbations. l-arginine has protective effects in several models of liver injury. This study was designed to investigate the possible protective effect of l-arginine against CIS-induced acute hepatic injury in rats. Rats were divided into 4 groups: control, l-arginine, CIS, l-arginine + CIS. Liver function, oxidative stress, inflammatory cytokines, and apoptosis markers were assessed. l-arginine pretreatment protected the liver against CIS-induced toxicity as indicated by significantly alleviating the changes in liver function along with restoration of the antioxidant status. This finding was confirmed with the markedly improved pathological changes. l-arginine showed anti-inflammatory effect through the reduction of liver expression of iNOS, TNF-α, and NF-κβ, which were ameliorated to significant levels. Furthermore, l-arginine administration downregulated the liver expression of the apoptotic marker, caspase-3. The results recommend l-arginine as a hepatoprotective agent against CIS toxicity. Mostly, this hepatoprotective effect of l-arginine involved anti-inflammatory and anti-apoptotic activities.

The Protective Effect of Magnolol in Osteoarthritis: In vitro and in vivo Studies

Osteoarthritis (OA), defined as a long-term progressive joint disease, is characterized by cartilage impairment and erosion. In recent decades, magnolol, as a type of lignin extracted from Magnolia officinalis, has been proved to play a potent anti-inflammatory role in various diseases. The current research sought to examine the latent mechanism of magnolol and its protective role in alleviating the progress of OA in vivo as well as in vitro experimentations. In vitro, the over-production of Nitric oxide (NO), prostaglandin E2 (PGE2), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6), induced by interleukin-1 beta (IL-1β), were all inhibited notably by magnolol in a concentration-dependent manner. Moreover, magnolol could also downregulate the expression of metalloproteinase 13 (MMP13) and thrombospondin motifs 5 (ADAMTS5). All these changes ultimately led to the deterioration of the extracellular matrix (ECM) induced by IL-1β. Mechanistically, magnolol suppressed the activation of PI3K/Akt/NF-κB pathway. Furthermore, a powerful binding capacity between magnolol and PI3K was also revealed in our molecular docking research. In addition, magnolol-induced protective effects in OA development were also detected in a mouse model. In summary, this research suggested that magnolol possessed a new therapeutic potential for the development of OA.

Therapeutic Potential of Plants and Plant Derived Phytochemicals against Acetaminophen-Induced Liver Injury

Acetaminophen (APAP), which is also known as paracetamol or N-acetyl-p-aminophenol is a safe and potent drug for fever, pain and inflammation when used at its normal therapeutic doses. It is available as over-the-counter drug and used by all the age groups. The overdose results in acute liver failure that often requires liver transplantation. Current clinical therapy for APAP-induced liver toxicity is the administration of N-acetyl-cysteine (NAC), a sulphydryl compound an approved drug which acts by replenishing cellular glutathione (GSH) stores in the liver. Over the past five decades, several studies indicate that the safety and efficacy of herbal extracts or plant derived compounds that are used either as monotherapy or as an adjunct therapy along with conventional medicines for hepatotoxicity have shown favorable responses. Phytochemicals mitigate necrotic cell death and protect against APAP-induced liver toxicityby restoring cellular antioxidant defense system, limiting oxidative stress and subsequently protecting mitochondrial dysfunction and inflammation. Recent experimental evidences indicat that these phytochemicals also regulate differential gene expression to modulate various cellular pathways that are implicated in cellular protection. Therefore, in this review, we highlight the role of the phytochemicals, which are shown to be efficacious in clinically relevant APAP-induced hepatotoxicity experimental models. In this review, we have made comprehensive attempt to delineate the molecular mechanism and the cellular targets that are modulated by the phytochemicals to mediate the cytoprotective effect against APAP-induced hepatotoxicity. In this review, we have also defined the challenges and scope of phytochemicals to be developed as drugs to target APAP-induced hepatotoxicity.

Modulation of Rat Hepatic CYP1A and 2C Activity by Honokiol and Magnolol: Differential Effects on Phenacetin and Diclofenac Pharmacokinetics In Vivo

Honokiol (2-(4-hydroxy-3-prop-2-enyl-phenyl)-4-prop-2-enyl-phenol) and magnolol (4-Allyl-2-(5-allyl-2-hydroxy-phenyl)phenol) are the major active polyphenol constituents of Magnolia officinalis (Magnoliaceae) bark, which has been widely used in traditional Chinese medicine (Houpu Tang) for the treatment of various diseases, including anxiety, stress, gastrointestinal disorders, infection, and asthma. The aim of this study was to investigate the direct effects of honokiol and magnolol on hepatic CYP1A and 2C-mediated metabolism in vitro using rat liver microsomes and in vivo using the Sprague-Dawley rat model. Honokiol and magnolol inhibited in vitro CYP1A activity (probe substrate: phenacetin) more potently than CYP2C activity (probe substrate: diclofenac): The mean IC₅₀ values of honokiol for the metabolism of phenacetin and diclofenac were 8.59 μM and 44.7 μM, while those of magnolol were 19.0 μM and 47.3 μM, respectively. Notably, the systemic exposure (AUC and C_max) of phenacetin, but not of diclofenac, was markedly enhanced by the concurrent administration of intravenous honokiol or magnolol. The differential effects of the two phytochemicals on phenacetin and diclofenac in vivo pharmacokinetics could at least be partly attributed to their lower IC₅₀ values for the inhibition of phenacetin metabolism than for diclofenac metabolism. In addition, the systemic exposure, CL, and V_ss of honokiol and magnolol tended to be similar between the rat groups receiving phenacetin and diclofenac. These findings improve our understanding of CYP-mediated drug interactions with M. officinalis and its active constituents.

Mechanisms of acetaminophen-induced liver injury and its implications for therapeutic interventions

Acetaminophen (APAP) overdose is the leading cause of drug-induced acute liver failure in many developed countries. Mitochondrial oxidative stress is considered to be the predominant cellular event in APAP-induced liver injury. Accordingly, N-acetyl cysteine, a known scavenger of reactive oxygen species (ROS), is recommended as an effective clinical antidote against APAP-induced acute liver injury (AILI) when it is given at an early phase; however, the narrow therapeutic window limits its use. Hence, the development of novel therapeutic approaches that can offer broadly protective effects against AILI is clearly needed. To this end, it is necessary to better understand the mechanisms of APAP hepatotoxicity. Up to now, in addition to mitochondrial oxidative stress, many other cellular processes, including phase I/phase II metabolism, endoplasmic reticulum stress, autophagy, sterile inflammation, microcirculatory dysfunction, and liver regeneration, have been identified to be involved in the pathogenesis of AILI, providing new targets for developing more effective therapeutic interventions against APAP-induced liver injury. In this review, we summarize intracellular and extracellular events involved in APAP hepatotoxicity, along with emphatic discussions on the possible therapeutic approaches targeting these different cellular events.

Highly efficient production of functional recombinant human fibroblast growth factor 22 in E. coli and its protective effects on H2O2-lesioned L02 cells

In the 22 member mammalian FGF family, FGF22 belongs to FGF7 subfamily, and its effects are largely confined to the brain and skin. To explore the functions of FGF22 on other tissues and develop a large-scale production of recombinant human FGF22 (rhFGF22) without a fusion tag, a plasmid encoding human FGF22 (pET3a-rhFGF22) was used to express rhFGF22 in E. coli BL21 (DE3) pLysS. A large amount of rhFGF22 inclusion body protein was obtained. A two-step denaturing method successfully solubilized rhFGF22, and it was refolded and then purified in one step via heparin affinity chromatography. A yield of 105 mg rhFGF22 with a purity of up to 95% was obtained from 100 g wet bacteria. It was found that the rhFGF22 had biological activity, since it effectively attenuated H₂O₂-induced human hepatic L02 cell death. Analysis by qRT-PCR and Western blot demonstrated that rhFGF22 protects L02 cells from H₂O₂-induced oxidative damage via suppression of mitochondrial apoptosis pathways. In conclusion, the strategy described in this paper may provide a novel means to solve the production of insoluble rhFGF22 and shine new light on its translational potential.

Growth-Promoting and Antioxidant Effects of Magnolia Bark Extract in Chickens Uninfected or Co-Infected with Clostridium perfringens and Eimeria maxima as an Experimental Model of Necrotic Enteritis

BACKGROUND

Magnolia tree bark has been widely used in traditional Asian medicine. However, to our knowledge, no studies have been reported investigating the effects of dietary supplementation with magnolia bark extract in chickens.

OBJECTIVE

We tested the hypothesis that dietary supplementation of chickens with a Magnolia officinalis bark extract would increase growth performance in uninfected and Eimeria maxima/Clostridium perfringens co-infected chickens.

METHODS

A total of 168 chickens were fed from hatch either a standard diet or a diet supplemented with 0.33 mg or 0.56 mg M. officinalis bark extract/kg (M/H low or M/H high, respectively) from days 1 to 35. At day 14, half of the chickens were orally infected with E. maxima, followed by C. perfringens infection at day 18 to induce experimental avian necrotic enteritis. Daily feed intake, feed conversion ratio, body weight gain, and final body weight were measured as indicators of growth performance. Serum α1-acid glycoprotein (AGP) concentrations were measured as an indicator of systemic inflammation, and intestinal lesion scores were determined as a marker of disease progression. Transcript levels for catalase, heme oxygenase 1, and superoxide dismutase in the intestine, liver, spleen, and skeletal muscle were measured as indicators of antioxidant status.

RESULTS

Growth performance increased between days 1 and 35 in uninfected and E. maxima/C. perfringens co-infected chickens fed M/H-low or M/H-high diets compared with unsupplemented controls. Gut lesion scores were decreased, whereas AGP concentrations were unchanged, in co-infected chickens fed magnolia-supplemented diets compared with unsupplemented controls. In general, transcripts for antioxidant enzymes increased in chickens fed magnolia-supplemented diets compared with unsupplemented controls, and significant interactions between dietary supplementation and co-infection were observed for all antioxidant enzyme transcript levels.

CONCLUSION

Magnolia bark extract might be useful for future development of dietary strategies to improve poultry health, disease resistance, and productivity without the use of antibiotic growth promoters.

Magnolol Alleviates Inflammatory Responses and Lipid Accumulation by AMP-Activated Protein Kinase-Dependent Peroxisome Proliferator-Activated Receptor α Activation

Magnolol (MG) is a kind of lignin isolated from Magnolia officinalis, which serves several different biological functions, such as antifungal, anticancer, antioxidant, and hepatoprotective functions. This study aimed to evaluate the protective effect of MG against oleic acid (OA)-induced hepatic steatosis and inflammatory damage in HepG2 cells and in a tyloxapol (Ty)-induced hyperlipidemia mouse model. Our findings indicated that MG can effectively inhibit OA-stimulated tumor necrosis factor α (TNF-α) secretion, reactive oxygen species generation, and triglyceride (TG) accumulation. Further study manifested that MG significantly suppressed OA-activated mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways and that these inflammatory responses can be negated by pretreatment with inhibitors of extracellular regulated protein kinase and c-Jun N-terminal kinase (U0126 and SP600125, respectively). In addition, MG dramatically upregulated peroxisome proliferator-activated receptor α (PPARα) translocation and reduced sterol regulatory element-binding protein 1c (SREBP-1c) protein synthesis and excretion, both of which are dependent upon the phosphorylation of adenosine monophosphate (AMP)-activated protein kinase (AMPK), acetyl-CoA carboxylase, and AKT kinase (AKT). However, MG suspended the activation of PPARα expression and was thus blocked by pretreatment with LY294002 and compound c (specific inhibitors of AKT and AMPK). Furthermore, MG clearly alleviated serum TG and total cholesterol release; upregulated AKT, AMPK, and PPARα expression; suppressed SREBP-1c generation; and alleviated hepatic steatosis and dyslipidemia in Ty-induced hyperlipidemia mice. Taken together, these results suggest that MG exerts protective effects against steatosis, hyperlipidemia, and the underlying mechanism, which may be closely associated with AKT/AMPK/PPARα activation and MAPK/NF-κB/SREBP-1c inhibition.

The protective effects of magnolol on acute trinitrobenzene sulfonic acid‑induced colitis in rats

The present study aimed to investigate the protective effects of magnolol on acute 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis, and its underlying mechanisms. Experimental colitis was induced by intracolonic administration of TNBS/ethanol into rats. The model rats were randomly assigned into groups: TNBS, magnolol (high, medium and low doses), and salazosulfapyridine (positive control). All intervention regimens were administered by oral gavage, once a day for 7 consecutive days, 24 h after colitis induction. Histological and biochemical changes in colonic inflammation were evaluated by hematoxylin and eosin and immunohistochemistry, respectively. Rats treated with all doses of magnolol exhibited decreased colonic myeloperoxidase activity (P<0.05 vs. TNBS), reduced serum levels of proinflammatory cytokines [including interleukin (IL)-6 and IL-17], and downregulated Toll-like receptor-4 (TLR-4) mRNA expression. Histological analysis revealed that medium and high doses of magnolol conferred an anti-inflammatory effect, which was indicated by a decrease in disease activity index, an increase in thymus index, and downregulation of nuclear factor (NF)-κB p65 mRNA and TLR-4 protein expression. However, only high-dose magnolol significantly ameliorated the elevated colon weight/length ratio. The results of the present study indicate that magnolol exerts protective effects against acute TNBS-induced colitis in rats, and the TLR-4/NF-κB signaling pathway-mediated inhibitory effect on inflammatory cascades may contribute to the protective activity of magnolol.

Beneficial effect of magnolol on lupus nephritis in MRL/lpr mice by attenuating the NLRP3 inflammasome and NF‑κB signaling pathway: A mechanistic analysis

Lupus nephritis (LN) is a common complication of systemic lupus erythematosus. The present study aimed to elucidate the protective effect of magnolol (MG) on the progression of LN, via inhibition of key signaling pathways. The results of the present study demonstrated that administration of MG caused inhibition of the activation of NACHT, LRR and PYD domains‑containing protein 3 and interleukin‑1β production. Histopathological analysis confirmed that the vehicle‑treated group exhibited characteristic glomerular disease, which was observed to be suppressed following the administration of MG; a marked decrease in glomerular and vascular lesions was observed compared with the vehicle control. This decrease was further demonstrated through analysis of kidney sections. The expression level of cell surface glycoprotein F4/80 was demonstrated to be markedly decreased in the MG‑treated mice compared with the vehicle control group. The MG‑treated mice exhibited a marked decrease in serum and renal tumor necrosis factor‑α expression levels.

Red Yeast Rice Protects Circulating Bone Marrow-Derived Proangiogenic Cells against High-Glucose-Induced Senescence and Oxidative Stress: The Role of Heme Oxygenase-1

The inflammation and oxidative stress of bone marrow-derived proangiogenic cells (PACs), also named endothelial progenitor cells, triggered by hyperglycemia contributes significantly to vascular dysfunction. There is supporting evidence that the consumption of red yeast rice (RYR; Monascus purpureus-fermented rice) reduces the vascular complications of diabetes; however, the underlying mechanism remains unclear. This study aimed to elucidate the effects of RYR extract in PACs, focusing particularly on the role of a potent antioxidative enzyme, heme oxygenase-1 (HO-1). We found that treatment with RYR extract induced nuclear factor erythroid-2-related factor nuclear translocation and HO-1 mRNA and protein levels in PACs. RYR extract inhibited high-glucose-induced (30 mM) PAC senescence and the development of reactive oxygen species (ROS) in a dose-dependent manner. The HO-1 inducer cobalt protoporphyrin IX also decreased high-glucose-induced cell senescence and oxidative stress, whereas the HO-1 enzyme inhibitor zinc protoporphyrin IX and HO-1 small interfering RNA significantly reversed RYR extract-caused inhibition of senescence and reduction of oxidative stress in high-glucose-treated PACs. These results suggest that RYR extract serves as alternative and complementary medicine in the treatment of these diseases, by inducing HO-1, thereby decreasing the vascular complications of diabetes.

Magnolol additive as a replacer of antibiotic enhances the growth performance of Linwu ducks

Magnolol rich in Magnolia officinalis is a bioactive polyphenolic compound. The aim of this study was to examine the effects of magnolol additive (MA) on growth performance, expression levels of antioxidant-related genes, and intestinal mucosal morphology of Linwu ducks aged from 49 to 70 days, comparing with that of an antibiotic additive (colistin sulfate [CS]). A total of 275, 49-day-old ducks were assigned to 5 groups with 5 cages of 11 ducks each and fed diets supplemented with 0, 100, 200 and 300 mg of MA/kg and 300 mg of CS/kg for 3 weeks, respectively. The results showed that the average daily body weight gain (ADG) was increased significantly in MA-fed groups (200 and 300 mg/kg), compared with the basal diet (BD) group (P < 0.05). The mRNA levels of superoxide dismutase-1 (SOD1), manganese superoxide dismutase-2 (MnSOD2) and catalase (CAT) were also increased significantly in MA groups (P < 0.05). In addition, hematoxylin and eosin staining revealed that Linwu ducks fed the diets with MA had more intact intestinal mucosa than those fed the BD and CS diets. In addition, ileal villus height, ileal villus height/crypt depth ratio (V/C) and duodenal V/C were also improved significantly (P < 0.05). Taken together, these data demonstrated that MA is an effective feed additive to enhance the growth performance of the Linwu ducks by improving the antioxidant and intestinal mucosal status, suggesting that MA will be a potential additive to replace antibiotic (CS).

Redox Control of Antioxidant and Antihepatotoxic Activities of Cassia surattensis Seed Extract against Paracetamol Intoxication in Mice: In Vitro and In Vivo Studies of Herbal Green Antioxidant

The therapeutic potential of Cassia surattensis in reducing free radical-induced oxidative stress and inflammation particularly in hepatic diseases was evaluated in this study. The polyphenol rich C. surattensis seed extract showed good in vitro antioxidant. C. surattensis seed extract contained total phenolic content of 100.99 mg GAE/g dry weight and there was a positive correlation (r > 0.9) between total phenolic content and the antioxidant activities of the seed extract. C. surattensis seed extract significantly (p < 0.05) reduced the elevated levels of serum liver enzymes (ALT, AST, and ALP) and relative liver weight in paracetamol-induced liver hepatotoxicity in mice. Moreover, the extract significantly (p < 0.05) enhanced the antioxidant enzymes and glutathione (GSH) contents in the liver tissues, which led to decrease of malondialdehyde (MDA) level. The histopathological examination showed the liver protective effect of C. surattensis seed extract against paracetamol-induced histoarchitectural alterations by maximum recovery in the histoarchitecture of the liver tissue. Furthermore, histopathological observations correspondingly supported the biochemical assay outcome, that is, the significant reduction in elevated levels of serum liver enzymes. In conclusion, C. surattensis seed extract enhanced the in vivo antioxidant status and showed antihepatotoxic activities, which is probably due to the presence of phenolic compounds.

Magnolia officinalis (Hou Po) bark extract stimulates the Nrf2-pathway in hepatocytes and protects against oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

The highly aromatic bark of Magnolia officinalis Rehder and EH Wilson, (magnolia bark) has been widely used in traditional Chinese medicine where it is known as Hou Po. Historically the bark of the tree has been used for treating variety of disorders the most common use of magnolia bark in traditional prescription has been to treat stress and anxiety disorders. Till date it is not clear regarding the fundamental cellular pathway it modulates. NRF2 signaling has emerged as the central pathway that protects cells from variety of stressors this led us to hypothesize that basis for magnolia bark's effects could be via activating NRF2 pathway.

MATERIALS AND METHODS

We utilized variety of biochemical procedures like luciferase reporter assay, enzyme induction, gene expression to determine NRF2 inducing activity by magnolia bark extract and its significance. Further we identified the phytochemicals inducing this activity using bio-directed fractionation procedure.

RESULTS

In this study, we demonstrate that magnolia bark extract activates Nrf2-dependent gene expression and protects against hydrogen peroxide mediated oxidative stress in hepatocytes. We further identified through HPLC fractionation and mass spectroscopy that magnolol, 4-methoxy honokiol and honokiol are the active phytochemicals inducing the Nrf2-mediated activity. This could be the molecular basis for its numerous beneficial activity.

Metabolic interactions of magnolol with cytochrome P450 enzymes: uncompetitive inhibition of CYP1A and competitive inhibition of CYP2C

Magnolol (MAG; 5,5'-diallyl-2,2'-biphenyldiol) is a major bioactive component of Magnolia officinalis. We investigated the metabolic interactions of MAG with hepatic cytochrome P450 monooxygenase (CYP) through in vitro microsomal metabolism study using human (HLM) and rat liver microsomes (RLM). CYP2C and 3A subfamilies were significantly involved in the metabolism of MAG, while CYP1A subfamily was not in HLM and RLM. The relative contribution of phase I enzymes including CYP to the metabolism of MAG was comparable to that of uridine diphosphate glucuronosyltransferase (UGT) in RLM. Moreover, MAG potently inhibited the metabolic activity of CYP1A (IC50 of 1.62 μM) and 2C (IC50 of 5.56 μM), while weakly CYP3A (IC50 of 35.0 μM) in HLM and RLM. By the construction of Dixon plot, the inhibition type of MAG on CYP activity in RLM was determined as follows: uncompetitive inhibitor for CYP1A (Ki of 1.09-12.0 μM); competitive inhibitor for CYP2C (Ki of 10.0-15.2 μM) and 3A (Ki of 93.7-183 μM). Based on the comparison of the current IC50 and Ki values with a previously reported liver concentration (about 13 μM) of MAG after its seven times oral administration at a dose of 50 mg/kg in rats, it is suggested that MAG could show significant inhibition of CYP1A and 2C, but not CYP3A, in the in vivo rat system. These results could lead to further studies in clinically significant metabolism-mediated MAG-drug interactions.

Magnolol reduced TNF-α-induced vascular cell adhesion molecule-1 expression in endothelial cells via JNK/p38 and NF-κB signaling pathways

Expression of cell adhesion molecules by the endothelium and the attachment of leukocytes to these cells play major roles in inflammation and cardiovascular disorders. Magnolol, a major active component of Magnolia officinalis, has antioxidative and anti-inflammatory properties. In the present study, the effects of magnolol on the expression of vascular cell adhesion molecule-1 (VCAM-1) in human aortic endothelial cells (HAECs) and the related mechanisms were investigated. TNF-α induced VCAM-1 protein expression and mRNA stability were significantly decreased in HAECs pre-treated with magnolol. Magnolol significantly reduced the phosphorylation of ERK, JNK, and p38 in TNF-α-treated HAECs. The decrease in VCAM-1 expression in response to TNF-α treatment was affected by JNK and p38 inhibitors, not by an ERK inhibitor. Magnolol also attenuates NF-κB activation and the translocation of HuR (an RNA binding protein) in TNF-α-stimulated HAECs. The VCAM-1 expression was weaker in the aortas of TNF-α-treated apo-E deficient mice with magnolol treatment. These data demonstrate that magnolol inhibits TNF-α-induced JNK/p38 phosphorylation, HuR translocation, NF-κB activation, and thereby suppresses VCAM-1 expression resulting in reduced leukocyte adhesion. Taken together, these results suggest that magnolol has an anti-inflammatory property and may play an important role in the prevention of atherosclerosis and inflammatory responses.

Epigallocatechin gallate attenuates proliferation and oxidative stress in human vascular smooth muscle cells induced by interleukin-1β via heme oxygenase-1

Proliferation of vascular smooth muscle cells (VSMCs) triggered by inflammatory stimuli and oxidative stress contributes importantly to atherogenesis. The association of green tea consumption with cardiovascular protection has been well documented in epidemiological observations, however, the underlying mechanisms remain unclear. This study aimed to elucidate the effects of the most active green tea catechin derivative, (−)-epigallocatechin-3-gallate (EGCG), in human aortic smooth muscle cells (HASMCs), focusing particularly on the role of a potent anti-inflammatory and antioxidative enzyme heme oxygenase-1 (HO-1). We found that pretreatment of EGCG dose- and time-dependently induced HO-1 protein levels in HASMCs. EGCG inhibited interleukin- (IL-)1β-induced HASMC proliferation and oxidative stress in a dose-dependent manner. The HO-1 inducer CoPPIX decreased IL-1β-induced cell proliferation, whereas the HO-1 enzyme inhibitor ZnPPIX significantly reversed EGCG-caused growth inhibition in IL-1β-treated HASMCs. At the molecular level, EGCG treatment significantly activated nuclear factor erythroid-2-related factor (Nrf2) transcription activities. These results suggest that EGCG might serve as a complementary and alternative medicine in the treatment of these pathologies by inducing HO-1 expression and subsequently decreasing VSMC proliferation.

Combination of honokiol and magnolol inhibits hepatic steatosis through AMPK-SREBP-1 c pathway

Honokiol and magnolol, as pharmacological biphenolic compounds of Magnolia officinalis, have been reported to have antioxidant and anti-inflammatory properties. Sterol regulatory element binding protein-1 c (SREBP-1 c) plays an important role in the development and processing of steatosis in the liver. In the present study, we investigated the effects of a combination of honokiol and magnolol on SREBP-1 c-dependent lipogenesis in hepatocytes as well as in mice with fatty liver due to consumption of high-fat diet (HFD). Liver X receptor α (LXRα) agonists induced activation of SREBP-1 c and expression of lipogenic genes, which were blocked by co-treatment of honokiol and magnolol (HM). Moreover, a combination of HM potently increased mRNA of fatty acid oxidation genes. HM induced AMP-activated protein kinase (AMPK), an inhibitory kinase of the LXRα-SREBP-1 c pathway. The role of AMPK activation induced by HM was confirmed using an inhibitor of AMPK, Compound C, which reversed the ability of HM to both inhibit SREBP-1 c induction as well as induce genes for fatty acid oxidation. In mice, HM administration for four weeks ameliorated HFD-induced hepatic steatosis and liver dysfunction, as indicated by plasma parameters and Oil Red O staining. Taken together, our results demonstrated that a combination of HM has beneficial effects on inhibition of fatty liver and SREBP-1 c-mediated hepatic lipogenesis, and these events may be mediated by AMPK activation.

Amelioration of paracetamol-induced hepatotoxicity in rat by the administration of methanol extract of Muntingia calabura L. leaves

Muntingia calabura L. is a tropical plant species that belongs to the Elaeocarpaceae family. The present study is aimed at determining the hepatoprotective activity of methanol extract of M. calabura leaves (MEMC) using two models of liver injury in rats. Rats were divided into five groups (n=6) and received 10% DMSO (negative control), 50 mg/kg N-acetylcysteine (NAC; positive control), or MEMC (50, 250, and 500 mg/kg) orally once daily for 7 days and on the 8th day were subjected to the hepatotoxic induction using paracetamol (PCM). The blood and liver tissues were collected and subjected to biochemical and microscopical analysis. The extract was also subjected to antioxidant study using the 2,2-diphenyl-1-picrylhydrazyl-(DPPH) and superoxide anion-radical scavenging assays. At the same time, oxygen radical antioxidant capacity (ORAC) and total phenolic content were also determined. From the histological observation, lymphocyte infiltration and marked necrosis were observed in PCM-treated groups (negative control), whereas maintenance of hepatic structure was observed in group pretreated with N-acetylcysteine and MEMC. Hepatotoxic rats pretreated with NAC or MEMC exhibited significant decrease (P<0.05) in ALT and AST enzymes level. Moreover, the extract also exhibited good antioxidant activity. In conclusion, MEMC exerts potential hepatoprotective activity that could be partly attributed to its antioxidant activity and, thus warrants further investigations.

Protective effects of 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone against hydrogen peroxide-induced oxidative stress in hepatic L02 cell

2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC) is a chalcone isolated from the buds of Cleistocalyx operculatus (Roxb.) Merr. et Perry, and the hepatoprotective effects of DMC on Kunming mice have been studied in previous study. However, the effects of DMC on hepatocyte toxicity and corresponding mechanism remain unclear. The aim of this study was to evaluate the hepatoprotective mechanism of DMC in human hepatocytes (L02) treated with H₂O₂. The results demonstrated that pretreatment with DMC effectively protected H₂O₂-induced cell viability loss, cell membrane damage (lactate dehydrogenase, nitric oxide production and caspase-3 accumulation. Besides, DMC pretreatment increased the amount of glutathione, decreased malondialdehyde and the percentage of apoptotic L02 cells compared with only H₂O₂ treated group. Taken together, these results indicated that DMC had hepatoprotective effects against H₂O₂-induced liver injury by alleviating oxidative stress and apoptosis process in L02 cells, and DMC might be a potential candidate for the intervention of liver diseases.

Immunochemical detection of lipid hydroperoxide- and aldehyde-modified proteins in diseases

Polyunsaturated fatty acid (PUFA) is easily peroxidized by free radicals and enzymes. When this occurs, it results in the compromised integrity of cellular membranes and leads to lipid hydroperoxide as a major reaction product, which is decomposed into aldehyde. Lipid hydroperoxide-modified lysine is known to be an early product of the lipid peroxidation process, suggesting that it might be a PUFA-oxidative stress marker during the initial stage of oxidative stress. Lipid hydroperoxides cause or enhance ROS-mediated DNA fragmentation. The α,β-unsaturated aldehydes are end products of PUFA peroxidation. They are highly reactive and readily attack and modify the protein amino acid residues into aldehyde-modified proteins. Lipid peroxidation-derived α,β-unsaturated aldehydes are capable of inducing cellular stress-responsive processes such as cell signaling and apoptosis. The lipid hydroperoxide- and aldehyde-modified proteins have been immunohistochemically detected in diverse pathological situations such as atherosclerosis, Alzheimer's disease, Parkinson's disease, and chemical material-induced liver injury and renal tubular injury in humans and experimental animals. These findings suggest that the expression of the lipid hydroperoxide- and aldehyde-modified proteins is closely associated with the pathogenesis of these diseases in humans and experimental animals.

Effects of an Agaricus blazei aqueous extract pretreatment on paracetamol-induced brain and liver injury in rats

The action of an Agaricus blazei aqueous extract pretreatment on paracetamol injury in rats was examined not only in terms of the classical indicators (e.g., levels of hepatic enzymes in the plasma) but also in terms of functional and metabolic parameters (e.g., gluconeogenesis). Considering solely the classical indicators for tissue damage, the results can be regarded as an indication that the A. blazei extract is able to provide a reasonable degree of protection against the paracetamol injury in both the hepatic and brain tissues. The A. blazei pretreatment largely prevented the increased levels of hepatic enzymes in the plasma (ASP, ALT, LDH, and ALP) and practically normalized the TBARS levels in both liver and brain tissues. With respect to the functional and metabolic parameters of the liver, however, the extract provided little or no protection. This includes morphological signs of inflammation and the especially important functional parameter gluconeogenesis, which was impaired by paracetamol. Considering these results and the long list of extracts and substances that are said to have hepatoprotective effects, it would be useful to incorporate evaluations of functional parameters into the experimental protocols of studies aiming to attribute or refute effective hepatoprotective actions to natural products.

Hepatoprotective effects of mushrooms

The particular characteristics of growth and development of mushrooms in nature result in the accumulation of a variety of secondary metabolites such as phenolic compounds, terpenes and steroids and essential cell wall components such as polysaccharides, β-glucans and proteins, several of them with biological activities. The present article outlines and discusses the available information about the protective effects of mushroom extracts against liver damage induced by exogenous compounds. Among mushrooms, Ganoderma lucidum is indubitably the most widely studied species. In this review, however, emphasis was given to studies using other mushrooms, especially those presenting efforts of attributing hepatoprotective activities to specific chemical components usually present in the mushroom extracts.