Hepatoprotection of Graptopetalum paraguayense E. Walther on CCl₄-induced liver damage and inflammation

Potential of hydroxybenzoic acids from Graptopetalum paraguayense for inhibiting of herpes simplex virus DNA polymerase – metabolome profiling, molecular docking and quantum-chemical analysis

According to our previous investigation the total methanol extract from Graptopetalum paraguayense E. Walther demonstrates a significant inhibitory effect on herpes simplex virus type 1 (HSV-1). To clarify what causes this inhibitory activity on HSV-1, a metabolic profile of the plant was performed. Three main fractions: non-polar substances, polar metabolites and phenolic compounds were obtained and gas chromatography–mass spectrometry (GC-MS) analysis was carried out. Since it is well known that phenolic compounds show a significant anti-herpes effect and that viral DNA polymerase (DNApol) appears to play a key role in HSV virus replication, we present a docking and quantum-chemical analysis of the binding of these compounds to viral DNApol amino acids. Fourteen different phenolic acids found by GC-MS analyses, were used in molecular docking simulations. According to the interaction energies of all fourteen ligands in the DNApol pockets based on docking results, density functional theory (DFT) calculations were performed on the five optimally interacting with the receptor acids. It was found that hydroxybenzoic acids from phenolic fraction of Graptopetalum paraguayense E. Walther show a good binding affinity to the amino acids from the active site of the HSV DNApol, but significantly lower than that of acyclovir. The mode of action on virus replication of acyclovir (by DNApol) is different from that of the plant phenolic acids one, probably.

Medicinal plants with hepatoprotective potentials against carbon tetrachloride-induced toxicity: a review

Background

Carbon tetrachloride (CCl4) is a well-characterized hepatotoxic agent. With rising cases of liver diseases, the identification, assessment, and development of hepatoprotective agents from plants source has become imperative.

Main body

With arrays of literature on plants with hepatoprotective potentials, this review sourced published literatures between 1998 and 2020 and systematically highlighted about 92 medicinal plants that have been reported to protect against CCl4-induced liver injury in animal models. The results show that herbal plants provide protection for the liver against CCl4 by downregulation of the liver marker enzymes and activation of antioxidant capacity of the liver cells with the restoration of liver architecture. We also provided the traditional and accompanying pharmacological uses of the plants. A variety of phytochemicals mostly flavonoids and polyphenols compounds were suggested to offer protection against liver injuries.

Conclusion

It can be concluded that there are a variety of phytochemicals in plant products with hepatoprotective activity against CCl4-induced toxicity in animal models.

Graptopetalum paraguayense Extract Ameliorates Proteotoxicity in Aging and Age-Related Diseases in Model Systems

Declines in physiological functions are the predominant risk factors for age-related diseases, such as cancers and neurodegenerative diseases. Therefore, delaying the aging process is believed to be beneficial in preventing the onset of age-related diseases. Previous studies have demonstrated that Graptopetalum paraguayense (GP) extract inhibits liver cancer cell growth and reduces the pathological phenotypes of Alzheimer’s disease (AD) in patient IPS-derived neurons. Here, we show that GP extract suppresses β-amyloid pathology in SH-SYS5Y-APP₆₉₅ cells and APP/PS1 mice. Moreover, AMP-activated protein kinase (AMPK) activity is enhanced by GP extract in U87 cells and APP/PS1 mice. Intriguingly, GP extract enhances autophagy in SH-SYS5Y-APP₆₉₅ cells, U87 cells, and the nematode Caenorhabditis elegans, suggesting a conserved molecular mechanism by which GP extract might regulate autophagy. In agreement with its role as an autophagy activator, GP extract markedly diminishes mobility decline in polyglutamine Q35 mutants and aged wild-type N2 animals in C. elegans. Furthermore, GP extract significantly extends lifespan in C. elegans.

Vescalagin from Pink Wax Apple (Syzygium samarangense (Blume) Merrill and Perry) Protects Pancreatic β-Cells against Methylglyoxal-Induced Inflammation in Rats

Methylglyoxal (MG) is the primary precursor of advanced glycation end products involved in the pathogenesis of inflammation and diabetes. A previous study in our laboratory found anti-inflammatory and anti-hyperglycemic effects of the polyphenol vescalagin (VES) in rats with MG-induced carbohydrate metabolic disorder. The present study further investigated the occurrence of inflammation in pancreatic β-cells in MG-induced diabetic rats and the mechanism by which VES prevents it. The results showed that VES downregulates the protein expression levels of advanced glycation end product receptors and CCAAT/enhancer binding protein-β and upregulates the protein expression levels of pancreatic duodenal homeobox-1, nuclear factor erythroid 2-related factor 2 and glyoxalase I from the pancreatic cells. The results also revealed that VES elevates glutathione and antioxidant enzyme contents and then downregulates c-Jun N-terminal kinase and p38 mitogen-activated protein kinases pathways to protect pancreatic β-cells in MG-administered rats.

Assessing the therapeutic potential of Graptopetalum paraguayense on Alzheimer's disease using patient iPSC-derived neurons

Alzheimer’s disease (AD) is the most common type of dementia and also one of the leading causes of death worldwide. However, the underlying mechanisms remain unclear, and currently there is no drug treatment that can prevent or cure AD. Here, we have applied the advantages of using induced pluripotent stem cell (iPSC)-derived neurons (iNs) from AD patients, which are able to offer human-specific drug responsiveness, in order to evaluate therapeutic candidates for AD. Using approach involving an inducible neurogenin-2 transgene, we have established a robust and reproducible protocol for differentiating human iPSCs into glutamatergic neurons. The AD-iN cultures that result have mature phenotypic and physiological properties, together with AD-like biochemical features that include extracellular β-amyloid (Aβ) accumulation and Tau protein phosphorylation. By screening using a gene set enrichment analysis (GSEA) approach, Graptopetalum paraguayense (GP) has been identified as a potential therapeutic agent for AD from among a range of Chinese herbal medicines. We found that administration of a GP extract caused a significantly reduction in the AD-associated phenotypes of the iNs, including decreased levels of extracellular Aβ40 and Aβ42, as well as reduced Tau protein phosphorylation at positions Ser214 and Ser396. Additionally, the effect of GP was more prominent in AD-iNs compared to non-diseased controls. These findings provide valuable information that suggests moving extracts of GP toward drug development, either for treating AD or as a health supplement to prevent AD. Furthermore, our human iN-based platform promises to be a useful strategy when it is used for AD drug discovery.

Antioxidant Activity of Graptopetalum paraguayense E. Walther Leaf Extract Counteracts Oxidative Stress Induced by Ethanol and Carbon Tetrachloride Co-Induced Hepatotoxicity in Rats

(1) Background: Graptopetalum paraguayense E. Walther is a traditional Chinese herbal medicine. In our previous study, 50% ethanolic G. paraguayense extracts (GE50) demonstrated good antioxidant activity. (2) Methods: To investigate the hepatoprotective effects of GE50 on ethanol and carbon tetrachloride (CCl₄) co-induced hepatic damage in rats, Sprague–Dawley rats were randomly divided into five groups (Control group; GE50 group, 0.25 g/100 g BW; EC group: Ethanol + CCl₄, 1.25 mL 50% ethanol and 0.1 mL 20% CCl₄/100 g BW; EC + GE50 group: Ethanol + CCl₄ + GE50; EC + silymarin group: ethanol + CCl₄ + silymarin, 20 mg/100 g BW) for six consecutive weeks. (3) Results: Compared with the control group, EC group significantly elevated the serum aspartate aminotransferase (AST), alanine aminitransferase (ALT), and lactate dehydrogenase (LDH). However, GE50 or silymarin treatment effectively reversed these changes. GE50 had a significant protective effect against ethanol + CCl₄ induced lipid peroxidation and increased the levels of glutathione (GSH), vitamin C, E, total antioxidant status (TAS), and the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and glutathione S-transferases (GST). Furthermore, in EC focal group, slight fat droplet infiltration was observed in the livers, while in the GE50 or silymarin treatment groups, decreased fat droplet infiltration. HPLC phytochemical profile of GE50 revealed the presence of gallic acid, flavone, genistin, daidzin, and quercetin. (4) Conclusions: The hepatoprotective activity of GE50 is proposed to occur through the synergic effects of its chemical component, namely, gallic acid, flavone, genistin, daidzin, and quercetin. Hence, G. paraguayense can be used as a complementary and alternative therapy in the prevention of alcohol + CCl₄-induced liver injury.

Graptopetalum paraguayense Inhibits Liver Fibrosis by Blocking TGF-β Signaling In Vivo and In Vitro

BACKGROUND AND AIMS

Liver fibrosis is the excessive accumulation of extracellular matrix proteins, including collagen, which occurs in most types of chronic liver diseases. Advanced liver fibrosis results in cirrhosis, liver failure, and portal hypertension. Activated hepatic perivascular stellate cells, portal fibroblasts, and myofibroblasts of bone marrow origin have been identified as major collagen-producing cells in the injured liver. These cells are activated by fibrogenic cytokines, such as TGF-β1. The inhibition of TGF-β1 function or synthesis is a major target for the development of antifibrotic therapies. Our previous study showed that the water and ethanol extracts of Graptopetalum paraguayense (GP), a Chinese herbal medicine, can prevent dimethylnitrosamine (DMN)-induced hepatic inflammation and fibrosis in rats.

METHODS

We used rat hepatic stellate HSC-T6 cells and a diethylnitrosamine (DEN)-induced rat liver injury model to test the potential mechanism of GP extracts and its fraction, HH-F3.

RESULTS

We demonstrated that GP extracts and HH-F3 downregulated the expression levels of extracellular matrix (ECM) proteins and inhibited the proliferation and migration via suppression of the TGF-β1 pathway in rat hepatic stellate HSC-T6 cells. Moreover, the HH-F3 fraction decreased hepatic collagen content and reduced plasma AST, ALT, and γ-GT activities in a DEN-induced rat liver injury model, suggesting that GP/HH-F3 has hepatoprotective effects against DEN-induced liver fibrosis.

CONCLUSION

These findings indicate that GP/HH-F3 may be a potential therapeutic agent for the treatment of liver fibrosis. The inhibition of TGF-β-mediated fibrogenesis may be a central mechanism by which GP/HH-F3 protects the liver from injury.

The Chinese medicine Kuan-Sin-Yin improves liver function in patients with chronic hepatitis C: A randomised and placebo-controlled trial

BACKGROUND & AIMS

This study examined the effects of a traditional Chinese medicine decoction, Kuan-Sin-Yin (KSY), on patients with chronic hepatitis C (CHC) in a randomised and placebo-controlled clinical trial.

METHODS

This trial enrolled 70 subjects with CHC who were randomised into 2 groups each with 35 participants. In total, 29 participants in the therapeutic group took 100mL of the herbal decoction daily, whereas 28 in the control group took an herbal placebo with the same dose and frequency for the 6-week study. The primary outcomes were liver function and viral load. Secondary measurements included haematopoietic and biochemical profiles, safety parameters, and a quality of life survey. All measurements were collected at the beginning of the study and after 6 weeks.

RESULTS

In within-group analysis, significant decreases of glutamate pyruvate transaminase (GPT) 31.7±75.2IU/L and glutamate oxaloacetate transaminase (GOT) 20.3±45.7IU/L were found in the KSY group (p=0.031 and 0.024, respectively). In the between-group analysis, KSY reduced serum GOT and GPT levels by more than 20IU/L (p=0.027 and 0.047, respectively). KSY also significantly decreased viral load by 0.3 log units (p=0.047). In addition, KSY significantly decreased serum triglyceride 16.9±27.5mg/dL (p=0.024).

CONCLUSIONS

This study demonstrates that taking the KSY herbal decoction for 6 weeks improves liver function and serum triglyceride levels and is safe for patients with CHC. The potential long-term effects of KSY on lipid metabolism related hepatoprotection and viral clearance warrant further investigation.

Gluconeogenesis, lipogenesis, and HBV replication are commonly regulated by PGC-1α-dependent pathway

PGC-1α, a major metabolic regulator of gluconeogenesis and lipogenesis, is strongly induced to coactivate Hepatitis B virus (HBV) gene expression in the liver of fasting mice. We found that 8-Br-cAMP and glucocorticoids synergistically induce PGC-1α and its downstream targets, including PEPCK and G6Pase. Also, HBV core promoter activity was synergistically enhanced by 8-Br-cAMP and glucocorticoids. Graptopetalum paraguayense (GP), a herbal medicine, is commonly used in Taiwan to treat liver disorders. Partially purified fraction of GP (named HH-F3) suppressed 8-Br-cAMP/glucocorticoid-induced G6Pase, PEPCK and PGC-1α expression and suppressed HBV core promoter activity. HH-F3 blocked HBV core promoter activity via inhibition of PGC-1α expression. Ectopically expressed PGC-1α rescued HH-F3-inhibited HBV surface antigen expression, HBV mRNA production, core protein levels, and HBV replication. HH-F3 also inhibited fatty acid synthase (FASN) expression and decreased lipid accumulation by down-regulating PGC-1α. Thus, HH-F3 can inhibit HBV replication, gluconeogenesis and lipogenesis by down-regulating PGC-1α. Our study indicates that targeting PGC-1α may be a therapeutic strategy for treatment of HBV infections. HH-F3 may have potential use for the treatment of chronic hepatitis B patients with associated metabolic syndrome.

Anti-inflammatory effect of water extracts of Graptopetalum paraguayense supplementation in subjects with metabolic syndrome: a preliminary study

BACKGROUND

Many studies have demonstrated that Graptopetalum paraguayense has good antioxidant ability; however, few studies have examined its anti-inflammatory effect. The study aimed to investigate the anti-inflammatory effects of water extracts of G. paraguayense (WGP, 4 g day(-1)) in subjects with metabolic syndrome (MS). Intervention was administered for 12 weeks. Levels of inflammatory markers [high sensitivity C-reactive protein (CRP), tumour necrosis factor-α (TNF-α), and interleukin-6 (IL-6)] and antioxidant enzymes activities were measured.

RESULTS

Forty-two subjects completed the 12 week intervention study (placebo, n = 19; WGP, n = 23). After 12 weeks supplementation, subjects in WGP group had significantly lower levels of inflammatory markers than the baseline (P < 0.05) and the placebo group (CRP, P = 0.07; TNF-α, P = 0.04; IL-6, P = 0.03). The changes in levels of the inflammatory markers were significantly decreased in WGP group (CRP, P = 0.04; TNF-α, P = 0.06; IL-6, P = 0.01) compared to the placebo group. Levels of inflammatory markers were significantly negatively correlated with the antioxidant enzymes activities after supplementation.

CONCLUSION

This study demonstrated a significant reduction in inflammatory status in MS after WGP supplementation. WGP may exert an anti-inflammatory effect on MS in addition to its antioxidant ability.

Chemical characterization and antioxidative activity of four 3-hydroxyl-3-methylglutaroyl (HMG)-substituted flavonoid glycosides from Graptopetalum paraguayense E. Walther

BACKGROUND

Graptopetalum paraguayense E. Walther is a popular traditional Chinese herb and possesses several health benefits. In earlier studies, we demonstrated that G. paraguayense showed no genotoxicity and showed several biological activities. However, the constituents of G. paraguayense have not been studied yet. In this present study, we isolated and identified the constituents of the leaves of G. paraguayense E. Walther.

RESULTS

A total of seven flavonoid compounds were isolated from the methanolic extract of G. paraguayense. The four major compounds isolated were flavonoid glucoside derivatives of quercetin (1, 3) and kampferol (2, 4), each presenting a 3-hydroxyl-3-methylglutaroyl (HMG) substituent; compounds 3 and 4-the 2´´-acetyl derivatives of 1 and 2, respectively-are novel compounds isolated from nature for the first time. High-performance liquid chromatography for the quantitative analyses of the four major HMG-substituted flavonoid glycosides in G. paraguayense E. Walther were accomplished to acquire the high yields of 1-4 in the methanolic extract (4.8, 5.7, 4.3, and 2.5 mg/g, respectively). Furthermore, the antioxidant activities, including radical-scavenging, reducing power and lipid peroxidation inhibitory effects of these isolated flavonoids were also evaluated. All seven of the isolated flavonoid compounds possessed antioxdative activity.

CONCLUSIONS

In this study of the constituents of the leaves of G. paraguayense E. Walther, we isolated four major components from its methanolic extract and determined their structures to be (acetylated) HMG-substituted flavonol glycosides, which are rare in nature. All seven of the isolated compounds possessed antioxdative activity, and those flavonoid compounds may be responsible for the functional ingredients in G. paraguayense. Further investigation of their bioactivities or pharmacological activities will be continued.

Hepatoprotective effects of Portulaca oleracea extract against CCl4-induced damage in rats

CONTEXT

Purslane (Portulaca oleracea L., Portulacaceae) has been traditionally used in folk medicine to afford protection against liver injury, although its actual efficacy remains uncertain.

OBJECTIVE

To evaluate purslane as a hepatoprotective agent, we investigated the protective effect of its ethanol extract against carbon tetrachloride (CCl4)-induced hepatic toxicity in rats.

MATERIALS AND METHODS

A total of 108 male Wistar rats were randomly divided into 12 groups. The first group was maintained as normal control, whereas CCl4 (0.5 ml/kg bw, 50% CCl4 in olive oil, i.p.), purslane extract (0.005, 0.01, 0.05, 0.1, and 0.15 g/kg bw, intragastrically), and purslane extract (five doses as above) along with CCl4 were administered to the Groups II, III-VII, and VIII-XII, respectively. The rats were sacrificed on the 30th day, and blood was withdrawn by cardiac puncture. Liver damage was assessed by measuring hepatic marker enzymes (ALT, AST, ALP, GGT, and SOD) and histopathological observation.

RESULTS

Treatment with CCl4 resulted in increased serum activities of marker enzymes with a concomitant decrease in SOD. Histological alterations were also observed in the liver tissue upon CCl4 treatment. Administration of purslane extract (0.01, 0.05, 0.1, and 0.15 g/kg b.w.) significantly showed a marked tendency towards normalization of all measured biochemical parameters in CCl4-treated rats. Histopathological changes also paralleled the detected alteration in markers of liver function.

DISCUSSION AND CONCLUSION

These results demonstrate that purslane exerts protective effects against CCl4-induced damage in rat liver and supports a potential therapeutic use of purslane as an alternative for patients with liver diseases.

Evaluation of the medicinal herb Graptopetalum paraguayense as a treatment for liver cancer

Background

Hepatocellular carcinoma (HCC) is the fifth most common malignancy and the third most common cause of cancer-related death worldwide. Sorafenib is the only drug for patients with advanced-stage hepatocellular carcinoma (HCC) that has been shown to confer a survival benefit to patients with HCC; however, it has many side effects. Thus, alternate therapeutic strategies with improved safety and therapeutic efficacy for the management of HCC should be developed.

Methods and Findings

We demonstrate that an extract of Graptopetalum paraguayense (GP) down-regulated the expression levels of several onco-proteins, including AURKA, AURKB, and FLJ10540, in HCC cells. To isolate the active components in the GP extracts, we prepared extracts fractions and assessed their effects on the expression of onco-proteins in HCC cells. The fraction designated HH-F3 was enriched in active ingredients, exhibited cytotoxic effects, and suppressed the expression of the onco-proteins in HCC cells. The structure of the main active compound in HH-F3 was found to be similar to that of the proanthocyanidin compounds derived from Rhodiola rosea. In addition, a distinct new compound rich in 3, 4, 5-trihydroxy benzylic moieties was identified in the HH-F3 preparations. Mechanistic studies indicated that HH-F3 induced apoptosis in HCC cells by promoting the loss of mitochondrial membrane potential and the production of reactive oxygen species. HH-F3 also enhanced PTEN expression and decreased AKT phosphorylation at Ser473 in a concentration-dependent manner in HCC cells. Moreover combination of GP or HH-F3 and sorafenib synergistically inhibits the proliferation of Huh7 cells. The treatment of a rat model with diethylnitrosamine (DEN)-induced liver cancer with extracts of GP and HH-F3 decreased hepatic collagen contents and inhibited tumor growth.

Conclusions

These results indicate that GP extracts and HH-F3 can protect the liver by suppressing tumor growth; consequently, these compounds could be considered for the treatment of HCC.

Hepatoprotective agent tethered isoniazid for the treatment of drug-induced hepatotoxicity: Synthesis, biochemical and histopathological evaluation

The aim of the study was to investigate the protective effect of isoniazid–curcumin conjugate (INH–CRM) in INH-induced hepatic injury by biochemical analysis and histology examination of liver in Wistar rats. The biochemical analysis included determination of the levels of plasma cholesterol, triglycerides (TG), albumin content, and lipid peroxidation (MDA). INH–CRM administration resulted in a significant decrease in plasma cholesterol, TG, and MDA levels in the liver tissue homogenate with an elevation in albumin level indicating its hepatoprotective activity. Histology of the liver further confirmed the reduction in hepatic injury. The hepatoprotective with INH–CRM can be attributed to the antioxidant activity of curcumin. The conjugate probably stabilizes the curcumin molecule, preventing its presystemic metabolism thereby enhancing its bioavailability and therefore, its hepatoprotective activity. Thus, the novel INH–CRM has the potential to alleviate INH-induced liver toxicity in antitubercular treatment.

Hepatoprotective potential of Cassia auriculata roots on ethanol and antitubercular drug-induced hepatotoxicity in experimental models

CONTEXT

Tarvada [Cassia auriculata Linn. (Caesalpiniaceae)] is used against liver ailments in Indian folk medicine, but there is a lack of scientific evidence for this traditional claim.

OBJECTIVE

The present study investigated the protective effect of methanol extract of tarvada (MECA) roots on ethanol and antitubercular drug induced hepatotoxicity in rats.

MATERIALS AND METHODS

In the therapeutic model, ethanol (40%, 4 g/kg b.w., p.o.) was administered to rats for 21 days and the intoxicated rats were treated with MECA (300 and 600 mg/kg, b.w.) and silymarin (100 mg/kg, b.w.) for next 7 days. In the prophylactic model, MECA and silymarin were administered simultaneously along with a combination of isoniazid (27 mg/kg, b.w.), rifampicin (54 mg/kg, b.w.) and pyrazinamide (135 mg/kg, b.w.) for 30 days. After the study duration, serum levels of AST, ALT, ALP, total bilirubin, total cholesterol, total protein, albumin were estimated along with hepatic catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA) and liver histopathology in each group.

RESULTS

Administration of tarvada root extract significantly (p < 0.01 and p < 0.05) lowered the elevated levels of serum AST, ALT, ALP, total bilirubin, total cholesterol, total protein and restored the abnormal levels of enzymatic antioxidants and MDA in liver due to toxicant administration in a dose-dependent manner. These results were confirmed by histopathological analysis.

DISCUSSION AND CONCLUSION

Results suggest that tarvada root extract possess potent hepatoprotective activity against ethanol and antitubercular drug-induced hepatotoxicity in rats, which could be due to an inhibition of hepatic metabolizing enzymes and antioxidant activity.

Effects of water extracts of Graptopetalum paraguayense on blood pressure, fasting glucose, and lipid profiles of subjects with metabolic syndrome

This study was aimed to investigate the effects of water extracts of Graptopetalum paraguayense (WGP, 4 g/d) on blood pressure, blood glucose level, and lipid profiles in subjects with metabolic syndrome (MS). Participants with MS (n = 54) were randomly assigned to the placebo (n = 28) and WGP groups (n = 26), and the intervention was administered for 12 weeks. Systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting glucose (FG), lipid profiles (total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), and high density lipoprotein (HDL-C)), and antioxidant enzymes activities (catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx)) were measured. Forty-two subjects completed the study (placebo, n = 19; WGP, n = 23). FG, SBP, and LDL-C levels were significantly lower and HDL-C level and antioxidant enzymes activities (CAT and SOD) were significantly higher after WGP supplementation. Blood pressure, FG, and lipid profiles were significantly correlated with antioxidant enzymes activities after supplementation (P < 0.05). The present study demonstrated a significant reduction in blood pressure, blood glucose, and lipid profiles and an increase in antioxidant enzymes activities in subjects with MS after WGP supplementation. Taken together, the antioxidative capacity of WGP might exert a beneficial effect on MS. This trial is registered with ClinicalTrials.gov NCT01463748.

Graptopetalum paraguayense and resveratrol ameliorates carboxymethyllysine (CML)-induced pancreas dysfunction and hyperglycemia

Hyperglycemia is associated with advanced glycation end products (AGEs). Recently, AGEs were found to cause pancreatic damage, oxidative stress, and hyperglycemia through the AGE receptor. Carboxymethyllysine (CML) is an AGE but whether it induces pancreatic dysfunction remains unclear. Graptopetalum paraguayense, a vegetable consumed in Taiwan, has been used in folk medicine and is an antioxidant that protects against liver damage. We investigated the protective properties of G. paraguayense 95% ethanol extracts (GPEs) against CML-induced pancreatic damage. The results indicated that resveratrol, GPE, and gallic acid (the active compound of GPE) increased insulin synthesis via upregulation of pancreatic peroxisome proliferator activated-receptor-γ (PPARγ) and pancreatic-duodenal homeobox-1 (PDX-1) but inhibited the expression of CML-mediated CCAAT/enhancer binding protein-β (C/EBPβ), a negative regulator of insulin production. Moreover, resveratrol and GPE also strongly activated nuclear factor-erythroid 2-related factor 2 (Nrf2) to attenuate oxidative stress and improve insulin sensitivity in the liver and muscle of CML-injected C57BL/6 mice and resulted in reduced blood glucose levels. Taken together, these findings suggested that GPE and gallic acid could potentially be used as a food supplement to protect against pancreatic damage and the development of diabetes.

Graptopetalum paraguayense Ameliorates Airway Inflammation and Allergy in Ovalbumin- (OVA-) Sensitized BALB/C Mice by Inhibiting Th2 Signal

Role of inflammation-induced oxidative stress in the pathogenesis and progression of chronic inflammatory airways diseases has received increasing attention in recent years. Nuclear factor erythroid 2-related factor 2 is the primary transcription factor that regulates the expression of antioxidant and detoxifying enzymes. Graptopetalum paraguayense E. Walther, a vegetable consumed in Taiwan, has been used in folk medicine for protection against liver injury through elevating antioxidation. Recently, we found that gallic acid is an active compound of Graptopetalum paraguayense E. Walther, which has been reported to inhibit T-helper 2 cytokines. Currently, we assumed that Graptopetalum paraguayense E. Walther may potentially protect against ovalbumin-induced allergy and airway inflammation. Results demonstrated that Graptopetalum paraguayense E. Walther ethanolic extracts (GPE) clearly inhibited airway inflammation, mucus cell hyperplasia, and eosinophilia in OVA-challenged mice. Additionally, GPE also prevented T-cell infiltration and Th2 cytokines, including interleukin- (IL-)4, IL-5, and IL-13 generations in bronchial alveolar lavage fluid. The adhesion molecules ICAM-1 and VCAM-1 were substantially reduced by GPE treatment mediated by Nrf2 activation. Moreover, GPE attenuated GATA3 expression and inhibited Th2 signals of the T cells. These findings suggested that GPE ameliorated the development of airway inflammation through immune regulation.

Ethanol Extract ofGraptopetalum paraguayenseUpregulates Paraoxonase 1 Gene Expression via an AKT/NF-κB-Dependent Pathway

Human serum paraoxonase 1 (PON1), a calcium-dependent ester hydrolase, protects against the oxidative modification of low-density lipoprotein (LDL) and is a major anti-atherosclerotic component of high-density lipoprotein (HDL). Graptopetalum paraguayense, a folk herbal medicine commonly used in Taiwan, has antioxidative, anti-inflammatory, anti-hypertensive, and anti-atherogenic properties. The effects of G. paraguayense on the activity and/or expression of PON1 were examined using various extracts of the plant; extracts were made in water (GPWE), 50% ethanol (GP50E), and 95% ethanol (GP95E). Of these extracts, GP50E was found to be the most effective at increasing the function and expression of PON1 in a human hepatoma HepG2 cell line. Data from electrophoretic mobility shift assays and promoter-reporter luciferase analyses demonstrated that the DNA binding activity and transactivation ability of NF-κB were enhanced by GP50E. Treatment with NF-κB inhibitors, pyrrolidine dithiocarbamate, and BAY 11-7082 significantly attenuated GP50E-induced PON1 production and NF-κB transactivation activity. In addition, GP50E increased the levels of phosphorylated protein kinase B (PKB/AKT). Pharmacological inhibition of AKT by LY294002 effectively suppressed NF-κB activation and PON1 gene expression, suggesting that AKT was an upstream regulator of GP50E-mediated biological events. Overall, the results show that GP50E up-regulated PON1 gene expression via an AKT/NF-κB-dependent signaling pathway in human hepatoma HepG2 cells. This observation led to the conclusion that the anti-atherogenic characteristics of G. paraguayense are modulated, at least in part, via the up-regulation of hepatocyte PON1 gene expression.

In vitro and in vivo safety of aqueous extracts of Graptopetalum paraguayense E. Walther

ETHNOPHARMACOLOGICAL RELEVANCE

Graptopetalum paraguayense E. Walther, a widely consumed vegetable in Taiwan, has many biological effects and has been used in folk medicine to alleviate hepatic disorders, exert diuretic effects, and relieve pain and infections. However, little data exist regarding its safety.

MATERIALS AND METHODS

Two genotoxicity assays were performed: chromosomal aberration of Chinese hamster ovary (CHO-K1 cells) (in vitro) and micronucleus assay in mice (in vivo). Acute oral toxicity and 28-day repeated feeding toxicity tests were performed by oral gavage in Sprague-Dawley (SD) rats.

RESULTS

GWE did not increase micronucleus ratios in vivo, and by chromosome aberration assay, GWE was safe up to 1.2mg/ml with regard to clastogenicity. Chromatid breakage was observed at high concentrations (2.5 and 5.0mg/ml) of GWE. GWE had no acute lethal effect at the maximum dose (5g/kg bw) in rats. In the 28-day study, there were no adverse effects on body weight, feed consumption, hematology, blood biochemical parameters, organ weight, or pathology.

CONCLUSION

The acute toxicity study showed that the LD(50) of GWE was greater than the tested dose (up to 1g/kg bw) in SD rats. In the subacute toxicity study, the no observed adverse effect level (NOAEL) of GWE in rats was 1g/kg bw. The in vivo study of mammalian erythrocyte micronuclei confirmed the Ames test results, demonstrating that GWE has no mutagenicity. High doses of GWE require further examination due to its clastogenic potential.