Protective effects of puerarin on carbon tetrachloride-induced hepatotoxicity

Protective effects of puerarin on metabolic diseases: Emphasis on the therapeutical effects and the underlying molecular mechanisms

Metabolic diseases (MetD) such as diabetes mellitus, obesity, and hyperlipidemia have become global health challenges. As a naturally occurring plant component, puerarin has been verified to possess a wide range of pharmacological effects including lowering blood glucose, improving insulin resistance, and regulating lipid metabolism, which has attracted extensive attention in recent years, and its potential in the treatment of MetD has been highly acclaimed. In addition, puerarin has exhibited antioxidant, anti-inflammatory, and cardiovascular protective effects, which are of great significance in the prevention and treatment of MetD. This article comprehensively summarizes the research progress of puerarin in the treatment of MetD and explores its pharmacological mechanisms, clinical applications, and future perspectives. More importantly, this review provided a list of the involved molecular mechanims in treating MetD of puerarin. Taking into account these conclusions, it may provide a strong foundation for the optimized use of puerarin in the treatment of patients suffering from MetD.

Investigating the Potential Therapeutic Mechanisms of Puerarin in Neurological Diseases

Plants and their derived phytochemicals have a long history of treating a wide range of illnesses for several decades. They are believed to be the origin of a diverse array of medicinal compounds. One of the compounds found in kudzu root is puerarin, a isoflavone glycoside commonly used as an alternative medicine to treat various diseases. From a biological perspective, puerarin can be described as a white needle crystal with the chemical name of 7-hydroxy-3-(4-hydroxyphenyl)-1-benzopyran-4-one-8-D-glucopyranoside. Besides, puerarin is sparingly soluble in water and produces no color or light yellow solution. Multiple experimental and clinical studies have confirmed the significant therapeutic effects of puerarin. These effects span a wide range of pharmacological effects, including neuroprotection, hepatoprotection, cardioprotection, immunomodulation, anticancer properties, anti-diabetic properties, anti-osteoporosis properties, and more. Puerarin achieves these effects by interacting with various cellular and molecular pathways, such as MAPK, AMPK, NF-κB, mTOR, β-catenin, and PKB/Akt, as well as different receptors, enzymes, and growth factors. The current review highlights the molecular mechanism of puerarin as a neuroprotective agent in the treatment of various neurodegenerative and neurological diseases. Extensive cellular, animal, and clinical research has provided valuable insights into its effectiveness in conditions such as Alzheimer's disease, Parkinson's disease, epilepsy, cerebral stroke, depression, and more.

Impact of dietary supplementation with chokeberry (Aronia melanocarpa, Michx.) on tetrachloride-induced liver injury in Wistar rats: Hematological and biochemical implication

In the current study, we assessed the hematological/biochemical alterations, histopathological changes in the liver, and blood cell disorders in Wistar rats exposed to a toxic concentration of carbon tetrachloride (CCl4 ) and the potential protective effect of a 30-day oral extract of chokeberry (Aronia melanocarpa, AM). The concentration of AM (3.38 mg/kg) obtained by quantitative purification from AM fruit showed the highest antioxidant activity (AOA) in vitro and was used for oral ingestion. In addition to high AOA, high values of total phenols (85.334 mg/g), total phenolic acid (606.95 mg/g), total flavonids (22.10 mg/g), and total anthocyanins (11.01 mg/g) were recorded in chokeberry extract. CCl4 treatment caused serious liver injury, hepatocyte and blood cell impairment. AM extract given to rats before CCl4 application had a moderate hepatoprotective effect in comparison to after CCl4 application. White blood count and leukocytes were significantly altered by CCl4, however, the protective role of AM in leukocyte disorders was not established. A high number of microcytes, stomatocytes, anisocytes, and hemolyzed erythrocytes during CCl4 exposure was reduced by AM extract. Flower erythrocytes in the AM + CCl4 group were recorded. Supplementation with chokeberry extract without CCl4 caused hyperproteinemia and hyperalbuminemia. Although the results indicate a weak protective role for AM, it is nevertheless important for improved erythropoiesis and regulation of the development of anemia. The hepatoprotective role of AM was moderate, and the immune response was not proven. Daily consumption of chokeberry extract can improve health. However, the results of our study showed that the ingestion of AM extract at this dose with the highest AOA would have more effective effects if the supplementation were significantly increased.

Puerarin attenuates cisplatin-induced apoptosis of hair cells through the mitochondrial apoptotic pathway

Puerarin, one of the main components of Pueraria lobata, has been reported to possess a wide range of pharmacological activities, including anti-inflammatory, antioxidative and anti-apoptotic effects. However, the role of puerarin in ototoxic drug-induced hair cell injury has not been well characterized. This study explored whether puerarin protects against cisplatin-induced hair cell damage and its potential mechanisms. The viability of puerarin-treated HEI-OC1 cells was assessed by CCK8 assay. Reactive oxygen species (ROS) was estimated with flow cytometric analysis using Cellrox Green fluorescent probe. Apoptosis-related protein levels were detected by western blot analysis. Immunostaining of the organ of Corti was performed to determine mice cochlear hair cell survival. Our results showed that puerarin improved cell viability and suppressed apoptosis in the cisplatin-damaged HEI-OC1 cells and cochlear hair cells. Mechanistic studies revealed that puerarin attenuated mitochondrial apoptosis pathway by regulating apoptotic related proteins, such as Bax and cleaved caspase-3, and attenuated ROS accumulation after cisplatin damage. Moreover, puerarin was involved in regulating the Akt pathway in HEI-OC1 cells in response to cisplatin. Our results demonstrated that puerarin administration decreased the sensitivity to apoptosis dependent on the mitochondrial apoptotic pathway by reducing ROS generation, which could be used as a new protective agent against cisplatin-induced ototoxicity.

Potential Effects of Dietary Isoflavones on Drug-Induced Liver Injury

Numerous prescribed drugs and herbal and dietary supplements have been reported to cause drug-induced acute liver injury, which is a frequent cause of acute liver failure (ALF). It is a tremendous challenge with ever-increasing drug application in the medication system for huge populations. Drug-induced acute liver injury can lead to diverse pathologies similar to acute and chronic hepatitis, acute liver failure, biliary obstruction, fatty liver disease, and so on. Recently, extensive work demonstrated that isoflavones play an essential and protecting role in drug-induced liver injury (DILI). The isoflavones mediated hepatoprotection by modulating specific genes linked with control of cellular redox homeostasis and inflammatory responses. Isoflavones upregulate oxidative stress-responsive nuclear factor erythroid 2-like 2 (Nrf2), downregulate inflammatory nuclear factor-κB (NF-κB) signaling pathways, and modulate a balance between cell survival and death. Moreover, isoflavones actively inhibit the expression of cytochromes P450 (CYPs) enzyme during drug metabolism. Moreover, isoflavones are also linked with farnesoid X receptor (FXR) activation and signal transducer and activator of transcription factor 3 (STAT3) phosphorylation in hepatoprotection DILI. In vivo and in vitro studies clearly stated that isoflavones bear strong antioxidant potential and promising agents for hepatotoxicity prevention and stressed their potential role as therapeutic supplements in DILI. The current review will elaborate on isoflavones’ preventive and therapeutic potential concisely and highlight various molecular targets to exert a protective effect on DILI.

Purified anthocyanins from Zea mays L. cob ameliorates chronic liver injury in mice via modulating of oxidative stress and apoptosis

BACKGROUND

Purple corn (Zea mays L.) is one of the main economic crops in China and has been used in the treatment of cystitis, urinary infections and obesity. However, purple corncobs, the by-product remaining after processing and having an intense purple-black color, are normally disposed of as waste or used as animal feed. Therefore, to further expand the medicinal value of purple corncob, its content was analyzed and, after purification, the effect and mechanism of purified purple corncob anthocyanins (PPCCA) on CCl₄ -induced chronic liver injury in mice were investigated.

RESULTS

It was observed that the total anthocyanin content (TAC) from PPCCA (317.51 ± 9.30 mg cyanidin 3-O-glucoside (C-3-G) g^-1 dry weight) was significantly higher than that from the purified purple corn seed anthocyanin (266.73 ± 3.67 mg C-3-G g^-1 dry weight), of which C-3-G accounted for 90.6% and 90.4% of the TAC, respectively. Furthermore, compared with the CCl₄ group, PPCCA treatment significantly reduced liver index, serum total bilirubin, alanine transaminase, aspartate transaminase and liver malondialdehyde levels, but increased liver superoxide dismutase activity. The pathological changes were also improved, such as more regular arrangement of hepatocytes, less swelling, and fewer vacuoles and apoptotic cells. Additionally, mechanistic studies showed that PPCCA downregulated the expression of Caspase-3, Bax and cytochrome P450 2E1 proteins in the liver and upregulated the expression of Bcl-2.

CONCLUSION

These results demonstrated that PPCCA could ameliorate CCl₄ -induced chronic liver injury by regulating oxidative stress and hepatocyte apoptosis pathways. © 2021 Society of Chemical Industry.

More natural more better: triple natural anti-oxidant puerarin/ferulic acid/polydopamine incorporated hydrogel for wound healing

Background

During wound healing, the overproduction of reactive oxygen species (ROS) can break the cellular oxidant/antioxidant balance, which prolongs healing. The wound dressings targeting the mitigation of ROS will be of great advantages for the wound healing. puerarin (PUE) and ferulic acid (FA) are natural compounds derived from herbs that exhibit multiple pharmacological activities, such as antioxidant and anti-inflammatory effects. Polydopamine (PDA) is made from natural dopamine and shows excellent antioxidant function. Therefore, the combination of natural antioxidants into hydrogel dressing is a promising therapy for wound healing.

Results

Hydrogel wound dressings have been developed by incorporating PUE or FA via PDA nanoparticles (NPs) into polyethylene glycol diacrylate (PEG-DA) hydrogel.

This hydrogel can load natural antioxidant drugs and retain the drug in the gel network for a long period due to the presence of PDA NPs. Under oxidative stress, this hydrogel can improve the activity of superoxide dismutase and glutathione peroxidase and reduce the levels of ROS and malondialdehyde, thus preventing oxidative damage to cells, and then promoting wound healing, tissue regeneration, and collagen accumulation.

Conclusion

Overall, this triple antioxidant hydrogel accelerates wound healing by alleviating oxidative injury. Our study thus provides a new way about co-delivery of multiple antioxidant natural molecules from herbs via antioxidant nanoparticles for wound healing and skin regeneration.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00973-7.

Puerarin improved growth performance and postmortem meat quality by regulating lipid metabolism of cattle under hot environment

This study aims to evaluate the effect of puerarin on performance, meat quality, and serum indexes of beef cattle under hot environment. Thirty-two bulls were divided into four groups and fed diet supplemented with puerarin at 0, 200, 400, or 800 mg/kg. Results showed that heat stress was employed for 54 out of 60 days, 400 mg/kg group declined serum cortisol (COR) contents, all treatments increased the contents of total cholesterol, high density lipoprotein cholesterol, and total superoxide dismutase activity; in addition, glutathione peroxidase activity of 200 mg/kg group were enhanced, only 800 mg/kg group enhanced immunoglobulin (IgA, IgM, and IgG) and low density lipoprotein cholesterol contents compared with the control (p < .05). Moreover, 400-mg/kg puerarin increased serum growth hormone levels compared with 200 mg/kg group but declined COR concentrations compared with 200 mg/kg and 800 mg/kg groups (p < .05). More importantly, average daily gain and daily matter intake, and intramuscular fat contents of 400 mg/kg group were enhanced, but the shear force of beef in 400 mg/kg and 800 mg/kg groups were declined compared with the control (p < .05). These findings indicated that supplemental with puerarin enhanced immune and antioxidant, and 400 mg/kg of puerarin improved performance and meat quality by normalizing levels of stress hormones and increasing intramuscular fat deposition of beef cattle under hot environment.

New insight and potential therapy for NAFLD: CYP2E1 and flavonoids

Over the years, the prevalence of nonalcoholic fatty liver disease (NAFLD) has increased year by year; however, due to its complicated pathogenesis, there is no effective treatment so far. It is reported that Cytochrome P450 2E1 (CYP2E1) plays an indispensable role in the development of NAFLD, and numerous studies have shown that flavonoids have a hepatoprotective effect and can exert a beneficial effect on NAFLD by regulating the activity of CYP2E1. Therefore, flavonoids may become effective drugs for the treatment of NAFLD in the future. This prompted us to review the research progress of the pathological mechanism of NAFLD and the impact of CYP2E1 activity changes during the pathological process, and to summarize the protective effect of flavonoids against CYP2E1 activity.

Potential Herb-Drug Interactions in the Management of Age-Related Cognitive Dysfunction

Late-life mild cognitive impairment and dementia represent a significant burden on healthcare systems and a unique challenge to medicine due to the currently limited treatment options. Plant phytochemicals have been considered in alternative, or complementary, prevention and treatment strategies. Herbals are consumed as such, or as food supplements, whose consumption has recently increased. However, these products are not exempt from adverse effects and pharmacological interactions, presenting a special risk in aged, polymedicated individuals. Understanding pharmacokinetic and pharmacodynamic interactions is warranted to avoid undesirable adverse drug reactions, which may result in unwanted side-effects or therapeutic failure. The present study reviews the potential interactions between selected bioactive compounds (170) used by seniors for cognitive enhancement and representative drugs of 10 pharmacotherapeutic classes commonly prescribed to the middle-aged adults, often multimorbid and polymedicated, to anticipate and prevent risks arising from their co-administration. A literature review was conducted to identify mutual targets affected (inhibition/induction/substrate), the frequency of which was taken as a measure of potential interaction. Although a limited number of drugs were studied, from this work, interaction with other drugs affecting the same targets may be anticipated and prevented, constituting a valuable tool for healthcare professionals in clinical practice.

Clinical Evaluation of Acetaminophen-Galgeuntang Interaction Based on Population Approaches

Galgeuntang (GGT), a traditional herbal medicine, is widely co-administered with acetaminophen (AAP) for treatment of the common cold, but this combination has not been the subject of investigation. Therefore, we investigated the herb–drug interaction between GGT and AAP by population pharmacokinetics (PKs) modeling and simulation studies. To quantify PK parameters and identify drug interactions, an open label, three-treatment, three-period, one-sequence (AAP alone, GGT alone, and AAP and GGT in combination) clinical trial involving 12 male healthy volunteers was conducted. Ephedrine (EPD), the only GGT component detected, was identified using a one-compartment model. The PKs of AAP were described well by a one-compartment model and exhibited two-phase absorption (rapid followed by slow) and first-order elimination. The model showed that EPD significantly influenced the PKs of AAP. The simulation results showed that at an AAP dose of 1000 mg × 4 times daily, the area under the concentration versus time curve of AAP increased by 16.4% in the presence of GGT compared to AAP only. In conclusion, the PKs of AAP were affected by co-administration of GGT. Therefore, when AAP is combined with GGT, adverse effects related to overdose of AAP could be induced possibly.

Inhibition of CYP2E1 and activation of Nrf2 signaling pathways by a fraction from Entada africana alleviate carbon tetrachloride-induced hepatotoxicity

Entada africana is used in non-conventional medicine for the management of liver ailments. A fraction, designated EaF10 (methylene chloride/methanol 90:10, v/v) with promising hepatoprotective activity has been isolated. Since the mechanisms underlying EaF10 hepatoprotective action remain unknown, this study was undertaken to investigate the anti-hepatotoxic mechanism of the fraction against carbon tetrachloride (CCl4)-induced hepatotoxicity and its antioxidant properties. Antioxidant activities of EaF10 were assessed through four chemical antioxidant assays and its anti-hepatotoxic effect evaluated in vivo and in vitro by post-treatment (25 or 100 mg/Kg) or co-treatment (6.25-100 μg/mL) in CCl4-intoxicated mice and normal human liver cells line L-02 hepatocytes respectively; and biochemical and molecular parameters assessed respectively by spectrophotometry, and by quantitative real-time polymerase chain reaction and western blot analysis. EaF10 exhibited strong antioxidant activities correlated with its polyphenol content. Serum levels of alanine/aspartate aminotransferase (AST/ALT) and nitrite oxide, liver contents of glutathione (GSH) protein carbonylation and malondialdehyde (MDA), liver activities of catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD) and cell viability showed the anti-hepatotoxic effect of EaF10, supported by histopathological observations. The fraction decreased the protein level of Cytochrome P450 2E1 (CYP2E1) and Kelch-like ECH-associated protein-1 (Keap-1), induced nuclear translocation of Nuclear factor-erythroid 2-related factor-2 (Nrf2) coupled to an increase of the mRNA levels of CAT, SOD1 and GST in CCl4-intoxicated L-02 hepatocytes. These findings evidenced that the studied plant fraction possesses a strong antioxidant capacity and prevents CCl4-induced hepatotoxicity, likely through inhibition of CYP2E1 and activation of the Nrf2 signaling pathway.

Safety evaluation of root extract of Pueraria lobata and Scutellaria baicalensis in rats

Background

The roots of Pueraria lobata and Scutellaria baicalensis, herbal medicines with a long history of widespread use, have been traditionally prescribed in combination to treat stroke, diabetes, and acute infectious diarrhea in East Asia. Nevertheless, toxicological data on these herbs and their combination are limited. This study investigated the acute and 13-week subchronic toxicity of root extract of P. lobata and S. baicalensis (HT047) for stroke treatment in male and female Sprague-Dawley rats.

Methods

In the acute toxicity study, HT047 was administered orally at a single dose of 5000 mg/kg. In the subchronic toxicity study, HT047 was administered orally at repeated daily doses of 800, 2000, and 5000 mg/kg/day for 13 weeks, followed by a 4-week recovery period.

Results

In the acute toxicity study, there were no deaths or toxicologically significant changes in clinical signs, body weight, and necropsy findings. In the subchronic toxicity study, HT047 at all doses caused no death and no treatment-related adverse effects on food consumption; organ weight; ophthalmologic, urinalysis, and hematological parameters; and necropsy findings of both rat sexes. There were some treatment-related alterations in clinical signs, body weight, and serum biochemistry and histopathological parameters; however, these changes were not considered toxicologically significant because they were resolved during the recovery period or resulted from the pharmacological effects of P. lobata and S. baicalensis.

Conclusions

The oral approximate lethal dose (the lowest dose that causes mortality) of HT047 was greater than 5000 mg/kg in male and female rats. The oral no-observed-adverse-effect level of HT047 was greater than 5000 mg/kg/day in rats of both sexes, and no target organs were identified. The present findings support the safety of an herbal extract of P. lobata and S. baicalensis as a therapeutic agent for stroke and further confirm the safety of the combined use of P. lobata and S. baicalensis in clinical practice.

Single or combined protective and therapeutic impact of taurine and hesperidin on carbon tetrachloride-induced acute hepatic injury in rat

Currently, hepatic injury due to environmental pollutants extremely threatens human health and elicits great concern. Hence, there is a high global interest to find natural novel formulation products with potent hepatoprotective activity to combat liver disease. Hence, we evaluated the protective or therapeutic effect of hesperidin (HSP) and taurine (TAU), individually and in combination, on carbon tetrachloride (CCl₄)-induced acute hepatic injury in rats. The pre- or posttreatment by HSP and/or TAU significantly depressed CCl₄-induced elevation of alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, gamma-glutamyl transferase, total bilirubin, direct bilirubin, indirect bilirubin, malondialdehyde, globulins (α1, α2, β, and γ), albumin/globulin ratio, triglycerides, total cholesterol, high-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol, nitric oxide, and myeloperoxidase levels. Also, the pre- or posttreatment by HSP and/or TAU significantly minimized CCl₄-induced reduction of superoxide dismutase, catalase, reduced glutathione, and albumin concentrations. Furthermore, the protective or therapeutic administration of HSP and/or TAU markedly restored the CCl₄-induced altered hepatic architecture, depleted glycogen, and DNA contents. Notably, alleviating CCl₄-induced hepatotoxicity was more prominent in the protective groups than the therapeutic groups. More importantly, most of biochemical and histopathological parameters of HSP+TAU did not significantly differ from those of separate TAU or HSP neither before nor after CCl₄ exposure. Conclusively, HSP or TAU could be candidate protective agents against CCl₄ hepatotoxic impacts but the combination of both bioactive offers only a limited synergistic effect. Graphical abstract.

Puerarin as potential treatment in diabetic retinopathy

Diabetic retinopathy (DR) is one of the most prevalent microvascular complications of diabetes, and the most leading cause of visual loss around the world. The lack of effective and approved treatment in DR is a major challenge for diabetic patients. Nowadays, natural compounds have got attention of the researchers for management of DR. Many evidences suggest that puerarin as a natural polyphenol exerts advantageous effects against DR. In the present review, we summarized the protective effects of puerarin against DR, and discussed the underlying mechanisms of these effects. Puerarin attenuates retinal neovascularization and neurodegeneration in diabetes mellitus, and the underlying mechanisms are related to antioxidant, anti-inflammatory, and antiapoptotic properties of the compound. In conclusion, puerarin might be a potential adjuvant agent for the prevention and treatment of DR. However, comprehensive studies are necessary to show its effectiveness and safety, particularly in human.

Puerarin protects rat liver and kidney against cadmium-induced oxidative stress

Oxidative stress is thought to be involved in cadmium (Cd) induced toxicity. This study examined the possible protective effect of puerarin on cadmium chloride (CdCl2, 2 mg/kg b.w.) induced toxicity in male rats. Male SD rats were treated with either intraperitoneal Cd and/or oral puerarin (100 mg/kg. b.w.) for 4 weeks. The results demonstrated that exposure to Cd led to an increase in the level of BUN, ALT and AST in serum. Cadmium raised the concentrations of MDA and GSH, and decreased antioxidants activities (SOD, CAT, and GSH-Px) in the liver and kidney. Conversely, administration of puerarin markedly attenuated Cd-induced biochemical alterations in serum, liver, and kidney tissues. These results suggest that puerarin exerts protective effects against Cd toxicity attributable to its antioxidant actions.

New hepatoprotective isoflavone glucosides from Pueraria lobata (Willd.) Ohwi

Two new isoflavone glucosides, 3'-methoxyneopuerarin A (1) and 3'-methoxyneopuerarin B (2), together with nine known isoflavones including puerarin (3), neopuerarin A (4), neopuerarin B (5), daidzin (6), daidzein (7), 3'-methoxypuerarin (PG-3) (8), puerarin xyloside (9), mirificin (10), 3'-hydroxypuerarin (11) were isolated from the water extraction of the dried roots of Pueraria lobata (Willd.) Ohwi. Their structures were elucidated by the means of spectroscopic and chromatographic analysis methods. All compounds were evaluated for their hepatoprotective activity on HepG2 cells. All of them showed statistically significant hepatoprotective effect.

Antioxidant and Anti-Inflammatory Effects of Herbal Formula SC-E3 in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages

SC-E3 is a novel herbal formula composed of five oriental medicinal herbs that are used to treat a wide range of inflammatory diseases in Korean traditional medicine. In this study, we sought to determine the effects of SC-E3 on free radical generation and inflammatory response in lipopolysaccharide- (LPS-) treated RAW 264.7 macrophages and the molecular mechanism involved. The ethanol extract of SC-E3 showed good free radical scavenging activity and inhibited LPS-induced reactive oxygen species generation. SC-E3 significantly inhibited the production of the LPS-induced inflammatory mediators, nitric oxide and prostaglandin E₂, by suppressing the expressions of inducible nitric oxide synthase and cyclooxygenase-2, respectively. SC-E3 also prevented the secretion of the proinflammatory cytokines, IL-1β, TNF-α, and IL-6, and inhibited LPS-induced NF-κB activation and the mitogen-activated protein kinase (MAPK) pathway. Furthermore, SC-E3 induced the expression of heme oxygenase-1 (HO-1) by promoting the nuclear translocation and transactivation of Nrf2. Taken together, these results suggest that SC-E3 has potent antioxidant and anti-inflammatory effects and that these effects are due to the inhibitions of NF-κB and MAPK and the induction of Nrf2-mediated HO-1 expression in macrophages. These findings provide scientific evidence supporting the potential use of SC-E3 for the treatment and prevention of various inflammatory diseases.

Antifibrotic effect of meloxicam in rat liver: role of nuclear factor kappa B, proinflammatory cytokines, and oxidative stress

This study was aimed at investigating the antifibrotic effect of meloxicam in CCl4-induced liver fibrosis and elucidating its underlying mechanism. Forty male rats were equally randomized for 8-week treatment with corn oil (negative control), CCl4 (to induce liver fibrosis), and/or meloxicam. Meloxicam effectively ameliorated the CCl4-induced alterations in liver histology, liver weight to body weight ratio, liver functions, and serum markers for liver fibrosis (hyaluronic acid, laminin, and PCIII). Meloxicam significantly abrogated CCl4-induced elevation of messenger RNA (mRNA) expressions for collagen I and alpha smooth muscle actin (α-SMA) and hepatic contents of hydroxyproline, transforming growth factor beta (TGF-β), and tissue inhibitor of matrix metalloproteases (TIMP-1). Meloxicam mitigated CCl4-induced elevation in hepatic levels of nuclear factor kappa B (NF-κB), tumor necrosis factor alpha (TNF-α), total nitric oxide (NO), interleukin-l beta (IL 1β), and prostaglandin E2 (PGE2). Meloxicam modulated CCl4-induced disturbance of liver cytochrome P450 subfamily 2E1 (CYP2E1) and glutathione-S-transferase (GST). The attenuation of meloxicam to liver fibrosis was associated with suppression of oxidative stress via reduction of lipid peroxides along with induction of reduced glutathione content and enhancement of superoxide dismutase, glutathione peroxidase, and catalase activities. This study provides an evidence for antifibrotic effect of meloxicam against CCl4-induced liver fibrosis in rat. The antifibrotic mechanism of meloxicam could be through decreasing NF-κB level and subsequent proinflammatory cytokine production (TNF-α, NO, IL-1 beta, and PGE2) and, hence, collagen deposition through inhibition of TIMP-1 and TGF-β. Abrogation of oxidative stress and modulation of liver-metabolizing enzymes (CYP2E1 and GST) were also involved.

Hepatoprotective effects of polymethoxyflavones against acute and chronic carbon tetrachloride intoxication

In the present study, we explore the protective effects of Citrus aurantium L. extract (CAE) against acute and chronic CCl4-induced hepatotoxicity. The quantitative analysis of CAE was performed using HPLC-UV to determine the nobiletin content was approximately 27%. For the acute model, the male ICR mice were orally treated with water, silymarin (positive control, 200 mg/kg) and CAE (50 and 200 mg/kg) for 3 days prior to CCl4 (1 mL/kg, 50% v/v in olive oil) IP injection. For the chronic model (n = 6/group), the mice were treated with each treatment for 28 consecutive days and CCl4 (1 mL/kg, 20%) was injected twice a week. In both the acute and chronic models, the CCl4 alone treated group showed histopathologic alterations with a significantly increase in serum hepatic enzyme levels together with a disrupted anti-oxidative status. In contrast, the CAE treatments restored pathologic alterations and recovered the oxidative status by enhancing antioxidant enzymes and reducing lipid peroxidation levels. Furthermore, CAE enhanced nuclear factor E2-related factor 2 (Nrf2) and its related cytoprotective signals, including NAD(P)H quinone oxidoreductase 1, UDP-glucuronosyltransferase, and γ-glutamylcysteine synthetase. Taken together, the present study demonstrates that CAE exerts a protective effect against CCl4-induced hepatotoxicity with its anti-oxidant, anti-inflammatory, and anti-apoptotic activity.

Antiproliferative activity and phenotypic modification induced by selected Peruvian medicinal plants on human hepatocellular carcinoma Hep3B cells

ETHNOPHARMACOLOGICAL RELEVANCE

The high incidence of human hepatocellular carcinoma (HCC) in Peru and the wide use of medicinal plants in this country led us to study the activity against HCC cells in vitro of somes species used locally against liver and digestive disorders.

MATERIALS AND METHODS

Ethnopharmacological survey: Medicinal plant species with a strong convergence of use for liver and digestive diseases were collected fresh in the wild or on markets, in two places of Peru: Chiclayo (Lambayeque department, Chiclayo province) and Huaraz (Ancash department, Huaraz province). Altogether 51 species were collected and 61 ethanol extracts were prepared to be tested. Biological assessment: All extracts were first assessed against the HCC cell line Hep3B according a 3-step multi-parametric phenotypic assay. It included 1) the evaluation of phenotypic changes on cells by light microscopy, 2) the measurement of the antiproliferative activity and 3) the analysis of the cytoskeleton and mitosis by immunofluorescence. Best extracts were further assessed against other HCC cell lines HepG2, PLC/PRF/5 and SNU-182 and their toxicity measured in vitro on primary human hepatocytes.

RESULTS

Ethnopharmacological survey: Some of the species collected had a high reputation spreading over the surveyed locations for treating liver problems, i.e. Baccharis genistelloides, Bejaria aestuans, Centaurium pulchellum, Desmodium molliculum, Dipsacus fullonum, Equisetum bogotense, Gentianella spp., Krameria lapacea, Otholobium spp., Schkuhria pinnata, Taraxacum officinale. Hep3B evaluation: Fourteen extracts from 13 species (Achyrocline alata, Ambrosia arborescens, Baccharis latifolia, Hypericum laricifolium, Krameria lappacea, Niphidium crassifolium, Ophryosporus chilca, Orthrosanthus chimboracensis, Otholobium pubescens, Passiflora ligularis, Perezia coerulescens, Perezia multiflora and Schkuhria pinnata) showed a significant antiproliferative activity against Hep3B cells (IC50≤ 50µg/mL). This was associated with a lack of toxicity on primary human hepatocytes in vitro. Immunofluorescence experiments on Hep3B cells showed that crude extracts of Schkuhria pinnata and Orthrosanthus chimboracensis could block Hep3B cells in mitosis with an original phenotype. Crude extracts of Perezia coerulescens, Perezia multiflora, Achyrocline alata, Ophryosporus chilca, Otholobium pubescens and Hypericum laricifolium could modify the overall microtubule cytoskeletal dynamics of Hep3B cells in interphase by an original mechanism.

CONCLUSIONS

Our method allowed us to select 9 extracts which displayed antiproliferative activities associated with original cellular phenotypes on Hep3B cells, regarding known microtubule-targeting drugs. Both chemical and cellular studies are ongoing in order to elucidate natural compounds and cellular mechanisms responsible of the activities described.

Apocynum venetum Attenuates Acetaminophen-Induced Liver Injury in Mice

Apocynum venetum L. (A. venetum) has long been used in oriental folk medicine for the treatment of some liver diseases; however, the underlying mechanisms remain to be fully elucidated. Acetaminphen (APAP) is a widely used analgesic drug that can cause acute liver injury in overdose situations. In this study, we investigated the potential protective effect of A. venetum leaf extract (ALE) against APAP-induced hepatotoxicity. Mice were intragastrically administered with ALE once daily for 3 consecutive days prior to receiving a single intraperitoneal injection of APAP. The APAP group showed severe liver injury characterized by the noticeable fluctuations in the following parameters: serum aminotransferases; hepatic malondialdehyde (MDA), 3-nitrotyrosine (3-NT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione (GSH). These liver damages induced by APAP were significantly attenuated by ALE pretreatments. A collective analysis of histopathological examination, DNA laddering and western blot for caspase-3 and cytochrome c indicated that the ALE is also capable of preventing APAP-induced hepatocyte death. Hyperoside, isoquercitrin and their derivatives have been identified as the major components of ALE using HPLC-MS/MS. Taken together, the A. venetum possesses hepatoprotective effects partially due to its anti-oxidant action.

Crocin Abrogates Carbon Tetrachloride-Induced Renal Toxicity in Rats via Modulation of Metabolizing Enzymes and Diminution of Oxidative Stress, Apoptosis, and Inflammatory Cytokines

This work aimed at investigating the potential modulatory effects and mechanisms of crocin against CCl4 -induced nephrotoxicity. Forty male rats were allocated for three weeks treatment with corn oil, CCl4 , crocin, or crocin plus CCl4 . Crocin effectively mitigated CCl4 -induced kidney injury as evidenced by amelioration of alterations in kidney histopathology, renal weight/100 g body weight ratio and kidney functions. Crocin modulated CCl4 -induced disturbance of kidney cytochrom-P450 subfamily 2E1 and glutathione-S-transferase. The attenuation of crocin to kidney injury was also associated with suppression of oxidative stress via reduction of lipid peroxides along with induction of renal glutathione content and enhancement of superoxide dismutase, glutathione peroxidase, and catalase activities. Crocin mitigated CCl4 -induced elevation of the renal levels of tumor necrosis factor-alpha, interleukin-6, prostaglandin E2, and active caspases-3. Collectively, crocin alleviated CCl4 -induced renal damage via modulation of kidney metabolizing enzymes, suppression of oxidative stress, inhibition of inflammatory cytokines, PGE2, and active caspase3 in kidney.

Large dose means significant effect--dose and effect relationship of Chi-Dan-Tui-Huang decoction on alpha-naphthylisothiocyanate-induced cholestatic hepatitis in rats

Background

Large dose application of traditional Chinese medicines has attracted more and more attentions in recent years. However, the scientific connotation of large dose application has not been clarified so far. The present study was designed to investigate the protective effects of Chi-Dan-Tui-Huang decoction (CDTHD) against Alpha-naphthylisothiocyanate (ANIT) induced acute cholestatic hepatitis in rats and explore the dose-effect relationship of CDTHD as a reference for clinical application.

Methods

The administration of CDTHD at a series of doses was performed twice each day for 5 days. The acute cholestasic hepatitis models were induced by intragastric administration of ANIT on the third day of CDTHD administration. Then, the protective effects on cholestatic hepatitis were investigated by examining the following parameters: body weights of rats, morphological and histopathological liver changes, the levels of serum biomarkers including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, direct bilirubin and γ-glutamyltranspeptidase. Furthermore, the dose-effect relationship was investigated with the application of correspondence analysis.

Result

In the tested range of doses, CDTHD at the maximum tolerance dose did not show any toxicity as time went on. The efficacy result showed that CDTHD from 21.6 g/kg⋅d to 86.4 g/kg⋅d exhibited significant hepatoprotective effect against ANIT-induced acute cholestatic hepatitis. It alleviated liver injury and reversed adverse biochemical and histopathological changes in a dose-dependent manner. Correspondence analysis showed that Radix Paeoniae Rubra in CDTHD was the main effective component and CDTHD could enhance the integrated efficacy in dose-dependent manner.

Conclusions

CDTHD is beneficial to liver protection in a dose-dependent manner. Especially large dose demonstrates potent efficacy and Radix Paeoniae Rubra in the formula contributes the main effect on ANIT-induced acute cholestatic hepatitis without toxicity.

Progress on the pharmacological research of puerarin: a review

Contemporary pharmacological research has demonstrated that puerarin, the most important phytoestrogen extracted from Pueraria lobata(Willd.) Ohwi, has protecting functions on the cardiovascular system, nervous system, osteoporosis, liver injury, and inflammation in vivo and in vitro. Most of these research studies focused on inhibiting oxidative stress and apoptosis through regulating various bioactivators and signal pathways. Among these, superoxide dismutase (SOD), endothelial nitric oxide synthase (eNOS) and malondialdehyde (MDA), and PI3K/Akt, MAPK, and NF-κB are of great importance. The data cited in this review were mainly obtained from articles listed in PubMed and Elsevier SDOL published from 1959 to 2013, and the search term used was "puerarin".

Novel insights into the mechanisms whereby isoflavones protect against fatty liver disease

Fatty liver disease (FLD) is a growing public health problem worldwide. There is an urgent requirement for alternative and natural medicine to treat this disease. As phytochemicals, isoflavones have attracted considerable attention for the prevention of FLD. Numerous studies have revealed that isoflavones protect against FLD through various pathways which modulate fatty acid β-oxidation, lipid synthesis, and oxidative stress. Recently, the aldose reductase (AR)/polyol pathway has been reported to be involved in the development of FLD by modulating hepatic fructose production, peroxisome proliferator-activated receptor (PPAR)α activity, cytochrome P450 (CYP)2E1 expression, and gut bacterial endotoxin-induced cytokine release. It has been reported that some isoflavones are potent AR inhibitors. Here, we review the anti-FLD actions of isoflavones and the proposed mechanism whereby isoflavones protect against FLD, with regard to the AR/polyol pathway. We propose that isoflavones block the AR/polyol pathway and in turn reduce fructose production and subsequent fat accumulation in the liver in diabetic or high-glucose-diet mice. In addition, in rodents with alcoholic liver disease or nonalcoholic fatty liver disease/nonalcoholic steatohepatitis, inhibition of AR by isoflavones may improve PPARα-mediated fatty acid oxidation, reduce hepatic steatosis, and attenuate CYP2E1-mediated oxidative stress or AR/gut bacterial endotoxin-mediated cytokine overproduction, to alleviate progression of FLD.

Mucoadhesive microparticles for gastroretentive delivery: preparation, biodistribution and targeting evaluation

The aim of this research was to prepare and characterize alginate-chitosan mucoadhesive microparticles containing puerarin. The microparticles were prepared by an emulsification-internal gelatin method using a combination of chitosan and Ca²⁺ as cationic components and alginate as anions. Surface morphology, particle size, drug loading, encapsulation efficiency and swelling ratio, in vitro drug released, in vitro evaluation of mucoadhesiveness and Fluorescence imaging of the gastrointestinal tract were determined. After optimization of the formulation, the encapsulation efficiency was dramatically increased from 70.3% to 99.2%, and a highly swelling ratio was achieved with a change in particle size from 50.3 ± 11.2 μm to 124.7 ± 25.6 μm. In ethanol induced gastric ulcers, administration of puerarin mucoadhesive microparticles at doses of 150 mg/kg, 300 mg/kg, 450 mg/kg and 600 mg/kg body weight prior to ethanol ingestion significantly protected the stomach ulceration. Consequently, significant changes were observed in inflammatory cytokines, such as prostaglandin E₂ (PGE₂), tumor necrosis factor (TNF-α), interleukin 6 (IL-6), and interleukin1β (IL-1β), in stomach tissues compared with the ethanol control group. In conclusion, core-shell type pH-sensitive mucoadhesive microparticles loaded with puerarin could enhance puerarin bioavailability and have the potential to alleviate ethanol-mediated gastric ulcers.

LC-MS/MS method for the determination of a new puerarin derivative and its application in pharmacokinetic studies in rats

AIM

To establish a sensitive and rapid liquid chromatographic-tandem mass spectrometry (LC-MS/MS) method for the quantitative analysis of dehydrated puerarin in rat plasma, and its application for pharmacokinetic studies.

METHODS

A plasma sample was pretreated by one-step protein precipitation by the addition of five volumes of methanol. The chromatographic separation was achieved on a Zorbax SB-C18 column (4.6 mm × 150 mm I.D. 5.0 μm, Agilent, USA) at 40 °C at a flow rate of 0.6 mL·min(-1) by an isocratic elution consisting of 10 mmol·L(-1) ammonium acetate in methanol and water containing 0.1% formic acid in a ratio of 20 : 80 (V/V). Detection was performed on a triple quadrupole mass spectrometer in multiple-reaction monitoring (MRM) mode. An atmospheric pressure chemical ionization (APCI) interface in positive ionization mode was used by monitoring the transitions from m/z 399.1→281.0 (dehydrated puerarin) and m/z 271.0→215.0 (internal standard, IS).

RESULTS

Calibration curves were linear in the concentration range from 1.50 to 5400 ng·mL(-1), and the lower limit of quantification (LLOQ) was 1.50 ng·mL(-1) in rat plasma. The accuracy and precision values, which were calculated from three different sets of quality control samples analyzed in sextuplicate on three different days, ranged from 95.73% to 103.18%, and from 4.33% to 7.86%, respectively.

CONCLUSION

The method was successfully applied to assess the pharmacokinetics of dehydrated puerarin after oral administration in rats.

Puerarin: a review of pharmacological effects

Puerarin is the major bioactive ingredient isolated from the root of the Pueraria lobata (Willd.) Ohwi, which is well known as Gegen (Chinese name) in traditional Chinese medicine. As the most abundant secondary metabolite, puerarin was isolated from Gegen in the late 1950s. Since then, its pharmacological properties have been extensively investigated. It is available in common foods and is used in alternative medicine. It has been widely used in the treatment of cardiovascular and cerebrovascular diseases, diabetes and diabetic complications, osteonecrosis, Parkinson's disease, Alzheimer's disease, endometriosis, and cancer. The beneficial effects of puerarin on the various medicinal purposes may be due to its wide spectrum of pharmacological properties such as vasodilation, cardioprotection, neuroprotection, antioxidant, anticancer, antiinflammation, alleviating pain, promoting bone formation, inhibiting alcohol intake, and attenuating insulin resistance. However, the direct molecular mechanisms and targets remain unclear. This review provides a comprehensive summary of the pharmacological effects of puerarin.

Puerarin attenuates neuronal degeneration in the substantia nigra of 6-OHDA-lesioned rats through regulating BDNF expression and activating the Nrf2/ARE signaling pathway

An increasing number of studies suggest that oxidative stress is associated with the Parkinsonian process. This study evaluated the potential neuroprotective role of puerarin (PR) on lesioned substantia nigra (SN) induced by 6-hydroxydopamine (6-OHDA). Data from a rotational test showed that PR treatment significantly decreased apomorphine-induced rotations. Both the dopamine (DA) content in the SN and the endogenous expression of brain-derived neurotrophic factor (BDNF) were also elevated by the treatment. Pathological examination showed that dopaminergic neuronal degeneration in the SN was attenuated by PR treatment. Meanwhile, the contents of γ-glutamylcysteine synthetase (γ-GCS), glutathione (GSH) and catalase (CAT) in SN tissue were gradually elevated. Additionally, cytochrome c oxidase (COX) mRNA expression in the SN was markedly up-regulated. At the same time, nuclear factor E2-related factor 2 (Nrf2) and Kelch-like ECH-associated protein 1 (Keapl) levels were progressively increased by the PR treatment. Our findings indicated that puerarin effectively protects against 6-OHDA-mediated oxidative stress injury in SN neurons, in which the underlying mechanisms are involved in modulating BDNF expression and activating the Nrf2/ARE signaling pathway.

Hepatoprotective effect of water extract from Chrysanthemum indicum L. flower

Background

Chrysanthemum indicum L. flower (CIF) has been widely used as tea in Korea. This study aims to investigate the hepatoprotective effect of the hot water extract of CIF (HCIF) in in vitro and in vivo systems.

Methods

Hepatoprotective activities were evaluated at 250 to 1000 μg/mL concentrations by an in vitro assay using normal human hepatocytes (Chang cell) and hepatocellular carcinoma cells (HepG2) against CCl₄-induced cytotoxicity. Cytochrome P450 2E1, which is a key indicator of hepatic injury, was detected by western blot analysis using rabbit polyclonal anti-human CYP2E1 antibody. An in vivo hepatoprotective activity assay was performed at 1000 to 4000 μg/mL concentrations on CCl₄-induced acute toxicity in rats, and the serum levels of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were determined by standard enzyme assays.

Results

The hepatoprotective effects of HCIF significantly reduced the levels of GOT (60.1%, P = 0.000) and GPT (64.5%, P = 0.000) compared with the vehicle control group (CCl₄ alone). The survival rates of HepG2 and Chang cells were significantly improved compared with the control group [82.1% (P = 0.034) and 62.3% (P = 0.002), respectively]. HCIF [50 mg/kg body weight (BW)] treatment significantly reduced the serum levels of GOT (49.5%, P = 0.00), GPT (55.5%, P = 0.00), ALP (30.8%, P = 0.000) and LDH (45.6%, P = 0.000) compared with the control group in this in vivo study. The expression level of cytochrome P450 2E1 (CYP2E1) protein was also significantly decreased at the same concentration (50 mg/kg BW; P = 0.018).

Conclusion

HCIF inhibited bioactivation of CCl₄-induced hepatotoxicity and downregulates CYP2E1 expression in vitro and in vivo.

Hepatoprotective effect of Origanum vulgare in Wistar rats against carbon tetrachloride-induced hepatotoxicity

The effect of an aqueous extract of Origanum vulgare (OV) leaves extract on CCl4-induced hepatotoxicity was investigated in normal and hepatotoxic rats. To evaluate the hepatoprotective activity of OV, rats were divided into six groups: control group, O. vulgare group, carbon tetrachloride (CCl4; 2 ml/kg body weight) group, and three treatment groups that received CCl4 and OV at doses of 50, 100, 150 mg/kg body weight orally for 15 days. Alanine amino transferase (ALT), alkaline phosphatase (ALP), and aspartate amino transferase (AST) in serum, lipid peroxide (LPO), GST, CAT, SOD, GPx, GR, and GSH in liver tissue were estimated to assess liver function. CCl4 administration led to pathological and biochemical evidence of liver injury as compared to controls. OV administration led to significant protection against CCl4-induced hepatotoxicity in dose-dependent manner, maximum activity was found in CCl4 + OV3 (150 mg/kg body weight) groups and changes in the hepatocytes were confirmed through histopathological analysis of liver tissues. It was also associated with significantly lower serum ALT, ALP, and AST levels, higher GST, CAT, SOD, GPx, GR, and GSH level in liver tissue. The level of LPO also decreases significantly after the administration of OV leaves extract. The biochemical observations were supplemented with histopathological examination of rat liver sections. Thus, the study suggests O. vulgare showed protective activity against CCl4-induced hepatotoxicity in Wistar rats and might be beneficial for the liver toxicity.

Puerarin mediates hepatoprotection against CCl4-induced hepatic fibrosis rats through attenuation of inflammation response and amelioration of metabolic function

This study was designed to evaluate the potential effects of puerarin (PR), an effective isoflavonoid compound purified from Pueraria lobata, in treating hepatic fibrosis (HF) rats induced by carbon tetrachloride (CCl(4), 2 mL kg(-1) d(-1)). Compared to model control, PR treatment effectively lowered the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (Alb), total protein (TP) in HF rats. Masson stained analysis showed that the condition of HF rats was mitigated. Meanwhile, the tumor necrosis factor alpha (TNF-α), nuclear factor-kappa B (NF-κB) expressions were significantly down-regulated at protein level by PR intervention. Additionally, the activity of superoxide dismutase (SOD) was elevated, while the content of malondialdehyde (MDA) was lessened in liver tissue. As revealed by immunohistochemistry assay, PR therapy resulted in reduced production of transforming growth factor-βl (TGF-βl). Moreover, it also was attributed to decreased mRNA level of inducible nitric oxide synthase (iNOS) using RT-PCR analysis. These findings demonstrate that puerarin successfully reverses hepatotoxicity in CCl(4)-induced HF rats via the underlying mechanisms of regulating serum enzymes and attenuating TNF-α/NF-κB pathway for anti-inflammation response, as well as improving metabolic function in liver tissue.

Protective role of puerarin on lead-induced alterations of the hepatic glutathione antioxidant system and hyperlipidemia in rats

Puerarin (PU), a natural flavonoid, has been reported to have many benefits and medicinal properties. The aim of the present study was to investigate the effects of puerarin on hepatic oxidative stress and hyperlipidemia in rats exposed to lead. Our data showed that puerarin significantly prevented lead-induced hepatotoxicity, indicated by both diagnostic indicators of liver damage (serum aminotransferase levels) and histopathological analysis. Moreover, lead-induced profound elevation of ROS production and oxidative stress, as evidenced by increasing of lipid peroxidation level, reducing of GPx, GST, GR and GCL activities and depleting of intracellular reduced GSH level in liver, were suppressed by treatment with puerarin. Furthermore, the increase of serum cholesterol, triglycerides and LDL induced by lead was effectively suppressed by puerarin. The HDL level in the lead treatment rats was also increased by puerarin. Western blot analysis showed that puerarin remarkably inhibited hyperlipidemia by regulating the expression of cholesterol 7a-hydroxylase (CYP7A1), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) and low-density lipoprotein receptor (LDL-R) in liver of lead treated rats. Altogether, these results suggest that puerarin could protect the lead-induced liver injury and hyperlipidemia by reducing ROS production, renewing the activities of antioxidant enzymes and influencing expression of hepatic lipid biosynthesis and metabolism genes.

Recent advances in herbal medicine for treatment of liver diseases

CONTEXT

Liver disease is a serious ailment and the scenario is worsened by the lack of precise therapeutic regimens. Currently available therapies for liver ailments are not apposite and systemic toxicity inhibits their long term use. Medicinal plants have been traditionally used for treating liver diseases since centuries as the toxicity factor appears to be on the lower side.

OBJECTIVE

Several phytochemials have been identified which have significant hepatoprotective activity with minimal systemic adverse effects which could limit their long term use. The scenario calls for extensive investigations which can lead to development of lead molecules for hepatoprotective molecules of future. This review deals with the biological activity, mode of action and toxicity and forthcoming application of some of these leads.

METHODS

These generally have strong antioxidative potential and cause induction of antioxidant enzymes like superoxide dismutase, reduced glutathione and catalase. Additional mechanisms of hepatoprotection include stimulation of heme oxygenase-1 activity, inhibition of nitric oxide production, hepatocyte apoptosis and nuclear factor-κB activation.

RESULTS AND CONCLUSION

Out of the several leads obtained from plant sources as potential hepatoprotective agents, silymarin, andrographolide, neoandrographolide, curcumin, picroside, kutkoside, phyllanthin, hypophyllanthin, and glycyrrhizin have been established as potent hepatoprotective agents. The hepatoprotective potential of several herbal medicines has been clinically evaluated. Significant efficacy has been seen with silymarin, glycyrrhizin and Liv-52 in treatment of hepatitis, alcoholic liver disease and liver cirrhosis.

Puerarin activates endothelial nitric oxide synthase through estrogen receptor-dependent PI3-kinase and calcium-dependent AMP-activated protein kinase

The cardioprotective properties of puerarin, a natural product, have been attributed to the endothelial nitric oxide synthase (eNOS)-mediated production of nitric oxide (NO) in EA.hy926 endothelial cells. However, the mechanism by which puerarin activates eNOS remains unclear. In this study, we sought to identify the intracellular pathways underlying eNOS activation by puerarin. Puerarin induced the activating phosphorylation of eNOS on Ser1177 and the production of NO in EA.hy926 cells. Puerarin-induced eNOS phosphorylation required estrogen receptor (ER)-mediated phosphatidylinositol 3-kinase (PI3K)/Akt signaling and was reversed by AMP-activated protein kinase (AMPK) and calcium/calmodulin-dependent kinase II (CaMKII) inhibition. Importantly, puerarin inhibited the adhesion of tumor necrosis factor (TNF)-α-stimulated monocytes to endothelial cells and suppressed the TNF-α induced expression of intercellular cell adhesion molecule-1. Puerarin also inhibited the TNF-α-induced nuclear factor-κB activation, which was attenuated by pretreatment with N(G)-nitro-L-arginine methyl ester, a NOS inhibitor. These results indicate that puerarin stimulates eNOS phosphorylation and NO production via activation of an estrogen receptor-mediated PI3K/Akt- and CaMKII/AMPK-dependent pathway. Puerarin may be useful for the treatment or prevention of endothelial dysfunction associated with diabetes and cardiovascular disease.