Echinocystic acid prevents obesity and fatty liver via interacting with FABP1

Long-term high-fat diet (HFD) will lead to obesity and their complications. Echinocystic acid (EA), a triterpene, shows anti-inflammatory and antioxidant effects. We predict that EA supplementation can prevent obesity, diabetes, and nonalcoholic steatohepatitis. To test our hypothesis, we investigated the effects of EA supplementation on mice with HFD-induced obesity in vivo and in vitro by adding EA to the diet of mice and the medium of HepG2 cells, the protein target of EA was analyzed by molecular docking. The results showed that EA ameliorated obesity and inhibited blood triglyceride and liver triglyceride concentrations than those in the HFD groups. The data on molecular docking indicated that FABP1 was a potential target of EA. Further experimental results confirmed that EA affected the triglyceride level by regulating the function of FABP1. This study may provide a new potential inhibitor for FABP1 and a new strategy for the treatment of obesity.

Echinocystic acid alleviated hypoxic-ischemic brain damage in neonatal mice by activating the PI3K/Akt/Nrf2 signaling pathway

Neonatal hypoxic-ischemic encephalopathy (HIE) is considered a major cause of death and long-term neurological injury in newborns. Studies have demonstrated that oxidative stress and apoptosis play a major role in the progression of neonatal HIE. Echinocystic acid (EA), a natural plant extract, shows great antioxidant and antiapoptotic activities in various diseases. However, it has not yet been reported whether EA exerts a neuroprotective effect against neonatal HIE. Therefore, this study was undertaken to explore the neuroprotective effects and potential mechanisms of EA in neonatal HIE using in vivo and in vitro experiments. In the in vivo study, a hypoxic-ischemic brain damage (HIBD) model was established in neonatal mice, and EA was administered immediately after HIBD. Cerebral infarction, brain atrophy and long-term neurobehavioral deficits were measured. Hematoxylin and eosin (H&E), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and dihydroethidium (DHE) staining were performed, and the contents of malondialdehyde (MDA) and glutathione (GSH) were detected. In the in vitro study, an oxygen-glucose deprivation/reperfusion (OGD/R) model was employed in primary cortical neurons, and EA was introduced during OGD/R. Cell death and cellular ROS levels were determined. To illustrate the mechanism, the PI3K inhibitor LY294002 and Nrf2 inhibitor ML385 were used. The protein expression levels of p-PI3K, PI3K, p-Akt, Akt, Nrf2, NQO1, and HO-1 were measured by western blotting. The results showed that EA treatment significantly reduced cerebral infarction, attenuated neuronal injury, and improved brain atrophy and long-term neurobehavioral deficits in neonatal mice subjected to HIBD. Meanwhile, EA effectively increased the survival rate in neurons exposed to OGD/R and inhibited oxidative stress and apoptosis in both in vivo and in vitro studies. Moreover, EA activated the PI3K/Akt/Nrf2 pathway in neonatal mice following HIBD and in neurons after OGD/R. In conclusion, these results suggested that EA alleviated HIBD by ameliorating oxidative stress and apoptosis via activation of the PI3K/Akt/Nrf2 signaling pathway.

Echinocystic Acid Facilitates Neurite Outgrowth in Neuroblastoma Neuro2a Cells and Enhances Spatial Memory in Aged Mice

Aging leads to functional changes in the brain and decreases ability of learning and memory. Neurite outgrowth is important in learning and memory, therefore regulation of neurite outgrowth might be a candidate for treating aged brain. Echinocystic acid (EA), a pentacyclic triterpene, has shown to exert various neurological effects. However, the effect of EA on neurite outgrowth has not been studied. In this study, we examined if EA is effective on neurite outgrowth and memory in aged mice. The effect of EA on neurite outgrowth was observed by examining neurite processes of Neuro2a cells treated with EA. Western blot analysis was conducted to examine possible mechanisms. Morris water maze test was used to examine the effect of EA on learning and memory in aged mice. Immunohistochemistry was conducted to observe the effect of EA on neurite outgrowth in the hippocampus. EA was shown to induce neurite outgrowth in a concentration dependent manner without affecting cell viability. Moreover, EA treatment increased phosphorylation of c-jun N-terminal kinase (JNK) and JNK inhibitor, SP600125, blocked the effect of EA on neurite outgrowth. These results demonstrated that EA treatment promotes neurite outgrowth through the JNK signaling pathway. In in vivo experiments, EA treatment increased neurite outgrowth in aged mouse hippocampus. Moreover, EA treatment enhanced spatial learning and memory in aged mice. These results suggest that EA can be developed as a new, naturally occurring drug to treat ageing-related neurological diseases.

Echinocystic acid ameliorates hyperhomocysteinemia-induced vascular endothelial cell injury through regulating NF-κB and CYP1A1

The present study investigated the role of echinocystic acid (EA) on the expression of nuclear factor (NF)-κB and cytochrome P450 1A1 (CYP1A1), and aortic morphology, in a rat model of hyperhomocysteinemia (Hhcy). A total of 50 Sprague Dawley rats were randomly divided into five groups as follows: Normal control (NC), model control (MC), vitamin control (VC; folic acid 1 mg/kg + vitamin B2 2 mg/kg + vitamin B12 10u g/kg), EA1 (20 mg/kg EA) and EA2 (40 mg/kg EA). Plasma homocysteine (Hcy) levels were determined via high performance liquid chromatography, and the morphology of the aorta was investigated using hematoxylin and eosin staining. Furthermore, aortic mRNA and protein levels of NF-κB and CYP1A1 were measured using reverse transcription-quantitative polymerase chain reaction analysis and western blotting, respectively. Plasma Hcy levels, and aortic mRNA and protein levels of NF-κB and CYP1A1, were significantly lower in the EA-treated group compared with the MC group (all P<0.05). However, the aortic morphology remained normal, including the endothelial cells of the inner layer, and smooth muscle cells of the media layer and adventitia. In conclusion, the results of the present study indicate that EA has a protective role on vascular endothelial cells in Hhcy through decreasing plasma Hcy, and thus NF-κB and CYP1A1 expression.

Echinocystic Acid Inhibits IL-1β-Induced COX-2 and iNOS Expression in Human Osteoarthritis Chondrocytes

Echinocystic acid (EA), a pentacyclic triterpene isolated from the fruits of Gleditsia sinensis Lam, displays a range of pharmacological activities including anti-inflammatory and antioxidant effects. However, the effect of EA on IL-1β-stimulated osteoarthritis chondrocyte has not been reported. The purpose of this study was to assess the effects of EA on IL-1β-stimulated human osteoarthritis chondrocyte. Chondrocytes were stimulated with IL-1β in the absence or presence of EA. NO and PGE2 production were measured by Griess reagent and ELISA. The expression of COX-2, iNOS, nuclear factor-κB (NF-κB), inhibitory kappa B (IκBα), c-Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK) were detected by Western blot analysis. The results showed that EA suppressed IL-1β-induced collagenase-3 (MMP-13), NO, and PGE2 production in a dose-dependent manner. IL-1β up-regulated the expression of COX-2 and iNOS, and the increase was inhibited by EA. Furthermore, IL-1β-induced NF-κB and mitogen-activated protein kinase (MAPK) activation were inhibited by EA. In conclusion, EA effectively attenuated IL-1β-induced inflammatory response in osteoarthritis chondrocyte which suggesting that EA may be a potential agent in the treatment of osteoarthritis.

Echinocystic acid, isolated from Gleditsia sinensis fruit, protects endothelial progenitor cells from damage caused by oxLDL via the Akt/eNOS pathway

AIMS

Our previous studies revealed that echinocystic acid (EA) showed obvious attenuation of atherosclerosis in rabbits fed a high-fat diet. However, the underlying mechanisms remain to be elucidated. Considering the importance of endothelial progenitor cells (EPCs) in atherosclerosis, we hypothesise that EPCs may be one of the targets for the anti-atherosclerotic potential of EA.

MAIN METHODS

After in vitro cultivation, EPCs were exposed to 100 μg/mL of oxidised low-density lipoprotein (oxLDL) and incubated with or without EA (5 and 20 μM) for 48 h. An additional two groups of EPCs (oxLDL+20 μM EA) were pre-treated with either wortmannin, an inhibitor of the phosphoinositide 3-kinase (PI3K) pathway, or nitro-l-arginine methyl ester (l-NAME), an endothelial nitric oxide synthase (eNOS)-specific inhibitor. Assessment of EPC apoptosis, adhesion, migration, and nitric oxide (NO) release was performed using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) staining, cell counting, caspase-3 activity assay, transwell chamber assay, and Griess reagent, respectively. The protein expression of protein kinase B (Akt) and eNOS was detected using Western blot.

KEY FINDINGS

Treatment of EPCs with oxLDL induced significant apoptosis and impaired adhesion, migration, and NO production. The deleterious effects of oxLDL on EPCs were attenuated by EA. However, when EPCs were pre-treated with wortmannin or l-NAME, the effects of EA were abrogated. Additionally, oxLDL significantly down-regulated eNOS protein expression as well as repression of eNOS and Akt phosphorylation.

SIGNIFICANCE

The inhibitory effect of oxLDL on Akt/eNOS phosphorylation was attenuated by EA. Taken together, the results indicate that EA protects EPCs from damage caused by oxLDL via the Akt/eNOS pathway.

Synthesis and anti-HCV entry activity studies of β-cyclodextrin-pentacyclic triterpene conjugates

In our previous studies, oleanolic acid (OA) and echinocystic acid (EA), isolated from Dipsacus asperoides, were found to have anti-HCV entry properties. The major issue for members of this type of triterpene is their low water solubility. In this study, a series of new water-soluble triazole-bridged β-cyclodextrin (CD)-pentacyclic triterpene conjugates were synthesized via click chemistry. Thanks to the attached β-CD moiety, all synthesized conjugates showed lower hydrophobicity (Alog P) than their parent compounds. Several conjugates exhibited moderate anti-HCV entry activity. With the exception of per-O-methylated β-CD-pentacyclic triterpene conjugates, all other conjugates showed no cytotoxicity based on an alamarBlue assay carried out with HeLa, HepG2, MDCK, and 293T cells. More interestingly, the hemolytic activity of these conjugates disappeared upon the introduction of β-CDs. Easy access to such conjugates that combine the properties of β-CD and pentacyclic triterpenes may provide a way to obtain a new class of anti-HCV entry inhibitors.