Protective Effect Of Ursolic Acid Research Articles

The Protective Effect of Ursolic Acid on Unilateral Ureteral Obstruction in Rats by Activating the Nrf2/HO-1 Antioxidant Signaling Pathway.

Renal interstitial fibrosis is a common pathological feature of a variety of kidney diseases that progress to end-stage renal disease. The excessive deposition of extracellular matrix (ECM) is a typical pathological change of renal interstitial fibrosis. The production of reactive oxygen species in renal tubules is an important factor leading to the development of renal interstitial fibrosis. Ursolic acid (UA) is a natural pentacyclic triterpene carboxylic acid compound widely found in plants. It has anti-inflammatory, antioxidant, and antitumor cell proliferation effects. It can reduce the development of fibrosis by inhibiting the oxidative stress response of the liver; there is currently no relevant research on whether UA can protect the renal interstitial fibrosis by resisting oxidative stress in the kidneys. In this study, our purpose is to investigate the effect of ursolic acid on renal interstitial fibrosis after unilateral ureteral obstruction (UUO) in rats and its related mechanisms. We established a UUO model by surgically ligating the right ureter of the rat and instilling UA preparation (40 mg/kg/d) through the stomach after the operation, once a day for 7 days. We found that UUO caused impaired renal function, increased pathological damage, increased renal interstitial fibrosis, increased apoptosis, increased oxidative stress damage, and decreased antioxidants. However, after UA preparations were given, the abovementioned damage was significantly improved. At the same time, we also found that UA preparations can significantly increase the relative expression of Nrf2/HO-1 signaling pathway in kidney tissue after UUO. In order to further verify whether the Nrf2/HO-1 signaling pathway is involved in the development of renal interstitial fibrosis, we injected zinc protoporphyrin (ZnPP, 45 umol/kg), a specific blocker of the Nrf2/HO-1 signaling pathway, into the intraperitoneal cavity after UUO in rats and before the gastric perfusion of ursolic acid preparations. Subsequently, we observed that the protective effect of UA on renal interstitial fibrosis after UUO in rats was reversed. Combining all the research results, we proved that UA has a protective effect on renal interstitial fibrosis after UUO in rats, which may be achieved by activating the Nrf2/HO-1 signaling pathway.

Protective Effect of Ursolic Acid in Prunella vulgaris L. on LPS-Induced Asthenozoospermia via Bcl-2/Bax Apoptosis Signaling Pathway.

Asthenozoospermia, also known as lack of sperm motility, accounts for about 27.8% of male infertility as a separate factor, and is often associated with abnormal quantity and morphology of spermatozoa. Therefore, oligozoospermia has become one of the most important factors affecting male infertility. Ursolic Acid (UA), also known as wusu acid, is the main active component isolated from Prunella vulgaris L. and has a variety of pharmacological effects. However, the protective effect of UA on asthenozoospermia disease has not been reported. In the current study, the purpose of this study was to investigate the regulatory effect of UA in rats with LPS-induced asthenozoospermia disease. SD rats were treated with 5 mg/kg LPS, respectively. After different concentrations of UA were infused into the stomach of SD rats, microscopy, flow cytometry, Enzyme-Linked Immunosorbent Assay (ELISA), qRT-PCR and western blot were used to detect sperm motility, apoptosis, the levels of TNF-α, IL-1β and IL-6, and Bcl-2/Bax apoptosis pathway related proteins in rat serum and epididymis tissues. Compared with the normal group, the sperm motility and Bcl-2 level in LPS group decreased significantly, while the expression of inflammatory factors and Bax proteins increased significantly (P<0.05). Compared with LPS group, UA intervention group has the opposite result and dose dependence. This study shows that UA can protect LPS-induced asthenozoospermia of rats by increasing sperm density and motility, regulating Bcl-2/Bax apoptosis pathway and reducing inflammatory apoptosis response. This experiment provides ideas for improving the clinical treatment of infertile patients with oligoasthenospermia.

Protective Effects of Ursolic Acid Against Cytotoxicity Induced by Corticosterone: Role of Protein Kinases.

Neuronal hippocampal death can be induced by exacerbated levels of cortisol, a condition usually observed in patients with Major depressive disorder (MDD). Previous in vitro and in vivo studies showed that ursolic acid (UA) elicits antidepressant and neuroprotective properties. However, the protective effects of UA against glucocorticoid-induced cytotoxicity have never been addressed. Using an in vitro model of hippocampal cellular death induced by elevated levels of corticosterone, we investigated if UA prevents corticosterone-induced cytotoxicity in HT22 mouse hippocampal derived cells. Concentrations lower than 25µM UA did not alter cell viability. Co-incubation with UA for 48h was able to protect HT22 cells from the reduction on cell viability and from the increase in apoptotic cells induced by corticosterone. Inhibition of protein kinase A (PKA), protein kinase C (PKC) and, Ca2+/calmodulin-dependent protein kinase II (CaMKII), but not phosphoinositide 3-kinase(PI3K), by using the pharmacological the inhibitors: H-89, chelerythrine, KN-62, and LY294002, respectively totally abolished the cytoprotective effects of UA. Finally, UA abrogated the reduction in phospho-extracellular signal-regulated kinases 1 and 2 (ERK1/2) but not in phospho-c-Jun kinases induced by corticosterone. These results indicate that the protective effect of UA against the cytotoxicity induced by corticosterone in HT22 cells may involve PKA, PKC, CaMKII, and ERK1/2 activation. The cytoprotective potential of UA against corticosterone-induced cytotoxicity and its ability to modulate intracellular signaling pathways involved in cell proliferation and survival suggest that UA may be a relevant strategy to manage stress-related disorders such as MDD.

Protective Effect of Ursolic Acid on the Intestinal Mucosal Barrier in a Rat Model of Liver Fibrosis

Oxidative stress mediated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) plays an important role in intestinal mucosal barrier damage in various disease states. Recent evidence suggests that intestinal mucosal barrier damage and intestinal dysbiosis occur in mice with hepatic fibrosis induced by CCl4 or bile duct ligation. Another study showed that ursolic acid (UA) attenuates experimental colitis via its anti-inflammatory and antioxidant activities. The goal of this study was to investigate the effects of UA on the intestinal mucosal barrier in CCl4-induced hepatic fibrosis in rats and identify its associated mechanisms. Male Sprague-Dawley rats were randomly divided into the following 3 groups (n = 10/group): the control, CCl4 model and UA treatment groups. Rats were sacrificed at 72 h after the hepatic fibrosis model was established and assessed for liver fibrosis, intestinal injury, enterocyte apoptosis, bacterial translocation, system inflammation, intestinal oxidative stress, and tight junction protein and NOX protein expression. The results demonstrated that UA attenuated the following: (i) liver and intestinal pathological injury; (ii) cleaved caspase-3 expression in the ileal epithelial cells; (iii) serum lipopolysaccharide and procalcitonin levels; (iv) intestinal malondialdehyde levels; and (v) the expression of the NOX protein components NOX2 and P67phox in ileal tissues. Furthermore, our results suggested that UA improved intestinal dysbiosis and the expression of the tight junction proteins Claudin 1 and Occludin in the ileum of rats. These results indicate that UA has protective effects on the intestinal mucosal barrier in rats with CCl4-induced liver fibrosis by inhibiting intestinal NOX-mediated oxidative stress. Our findings may provide a basis for further clinical studies of UA as a novel and adjuvant treatment to cure liver fibrosis.

Ursolic Acid Attenuates High Glucose-Mediated Mesangial Cell Injury by Inhibiting the Phosphatidylinositol 3-Kinase/Akt/Mammalian Target of Rapamycin (PI3K/Akt/mTOR) Signaling Pathway.

BackgroundTo investigate the protective effect of ursolic acid (UA) on high glucose (HG)-induced human glomerular mesangial cell injury and to determine whether UA inhibits cell proliferation and reactive oxygen species (ROS) production by suppressing PI3K/Akt/mTOR pathway activation.Material/MethodsHuman mesangial cells were cultured with normal glucose (NG group), high glucose (HG group), mannitol (mannitol hypertonic control group), or high glucose with different concentrations (0.5, 1.0, and 2.0 mmol/L) of UA (HG+UA groups). Cell proliferation and intracellular ROS levels were assessed by methyl thiazolyl tetrazolium (MTT) and dichloro-dihydro-fluorescein diacetate (DCFH-DA) flow cytometry assays, respectively. Western blotting was used to detect mesangial cell expression of PI3K/Akt/mTOR pathway components, including Akt, p-Akt, mTOR, and p-mTOR, and proteins related to cell injury, including TGF-β1 and fibronectin (FN). mRNA expression of TGF-β1 and FN were evaluated using real-time quantitative polymerase chain reaction (PCR).ResultsAbnormal proliferation was observed in human glomerular mesangial cells at 48 h after treatment with HG, and UA suppressed the HG-induced proliferation of mesangial cells in a dose-dependent manner. UA inhibited ROS generation and oxidative stress in mesangial cells and mitigated mesangial cell injury. Treatment with UA reduced Akt and mTOR phosphorylation levels in mesangial cells exposed to HG (p<0.05 vs. HG) and downregulated protein and mRNA expression of TGF-β1 and FN in these cells (p<0.05 vs. HG).ConclusionsUA attenuated mesangial cell proliferation and ROS generation by inhibiting HG-mediated PI3K/Akt/mTOR pathway activation, thereby ameliorating mesangial cell damage.

Ursolic acid protects hepatocytes against lipotoxicity through activating autophagy via an AMPK pathway

Ursolic acid is a naturally occurring pentacyclic triterpenoid in many plants, such as medicinal herbs and food, and was previously found to be an effective phytochemical that protected against high-fat diet-induced hepatic steatosis and liver injury. However, the molecular mechanisms are not fully determined. The present study examined the protective role of ursolic acid against saturated fatty acid-induced lipotoxicity. We found that ursolic acid protected HepG2 (hepatocellular carcinoma, human) cells against palmitate-induced cell death and mitochondrial dysfunction. The protective activity was the result of ursolic acid-induced autophagy, and an autophagy inhibitor prevented this protective effect. Ursolic acid activated/phosphorylated adenosine monophosphate-activated protein kinase (AMPK) and reduced phosphorylation of mammalian target of rapamycin. AMPK gene knockdown by siRNA transfection abolished the protective effect of ursolic acid. Ursolic acid induced autophagy in HepG2 cells to protect against palmitate-induced cell death via an AMPK/mTOR pathway.

Ursolic acid promotes the neuroprotection by activating Nrf2 pathway after cerebral ischemia in mice

BackgroundOxidative and inflammatory damages have been suggested to play an important role in cerebral ischemic pathogenesis, and provide promising therapeutic strategies for stroke. Nuclear factor-erythroid 2-related factor 2 (Nrf2), a pleiotropic transcription factor, has been shown to play a key role in protecting cells against oxidative injury in cerebral ischemia. In this study, we demonstrated the hypothesis that ursolic acid (UA), a natural pentacyclic triterpenoid acid, isolated from edible plants in the Oleaceae family, a well-known anti-oxidative and anti-inflammatory reagent, protects the brain against ischemic injury by activating the Nrf2 pathway. Methods: Nrf2−/− and wild-type (WT) mice were induced into focal cerebral ischemia by transient middle cerebral artery occlusion (MCAO), and received UA treatment immediately after MCAO. The behavioral dysfunction, infarct size, and the expression of Nrf2, HO-1 and inflammatory factors (TLR4 and NF-κB) in ischemic brain were measured at 24h after stroke. Results: UA treatment significantly improved neurological deficit and reduced infarct size in WT mice after MCAO. Administration of UA also decreased the product of lipid peroxidation, promoted the activation of Nrf2 pathway and decreased the expression of TLR4 and NF-KB after stroke in WT mice. However, Nrf2−/− mice demonstrated more severe neurologic deficits, infarct size and inflammatory damage after MCAO, and did not benefit from the protective effect of UA. Conclusion: The results indicated that UA protected the brain against ischemic injury in mice by anti-oxidative and anti-inflammatory effects after MCAO. Activation of the Nrf2 pathway contributes to the neuroprotective effects induced by UA in cerebral ischemia.

Effect of ursolic acid treatment on apoptosis and DNA damage in isoproterenol-induced myocardial infarction

The present study was designed to evaluate the protective effect of ursolic acid (UA) against isoproterenol-induced myocardial infarction. Myocardial infarction was induced by subcutaneous injection of isoproterenol hydrochloride (ISO) (85 mg/kg BW), for two consecutive days. ISO-induced rats showed elevated levels of cardiac troponins T (cTn T) and I (cTn I) and increased activity of creatine kinase-MB (CK-MB) in serum. Lipid peroxidative markers (thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and lipid hydroperoxides (HP)) elevated in the plasma and heart tissue whereas decreased activities of enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR)) in erythrocytes and heart tissue of ISO-induced rats. Non-enzymatic antioxidants (vitamin C, vitamin E and reduced glutathione (GSH)) levels were decreased significantly in the plasma and heart tissue of ISO-induced rats. Furthermore, ISO-induced rats showed increased DNA fragmentation, upregulations of myocardial pro-apoptotic B-cell lymphoma-2 associated-x (Bax), caspase-3, -8 and -9, cytochrome c, tumor necrosis factor-α (TNF-α), Fas and down-regulated expressions of anti-apoptotic B-cell lymphoma-2 (Bcl-2) and B-cell lymphoma-extra large (Bcl-xL). UA-administered rats showed decreased levels/activity of cardiac markers, DNA fragmentation and the levels of lipid peroxidative markers in the plasma and heart tissue. Activities of enzymatic antioxidants were increased significantly in the erythrocytes and heart tissue and also non-enzymatic antioxidants levels were increased significantly in the plasma and heart tissue in UA-administered rats. UA influenced decreased DNA fragmentation and an apoptosis by upregulation of anti-apoptotic proteins such as Bcl-2, Bcl-xL and down-regulation of Bax, caspase-3, -8 and -9, cytochrome c, TNF-α, Fas through mitochondrial pathway. Histopathological observations were also found in line with biochemical parameters. Thus, results of the present study demonstrated that the UA has anti-apoptotic properties in ISO-induced rats.

Ursolic acid reduces prostate size and dihydrotestosterone level in a rat model of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is characterized by hyperplasia of prostatic stromal and epithelial cells, which can lead to lower urinary tract symptoms. The prevalence of BPH increases in an age-dependent manner. We investigated the protective effect of ursolic acid in BPH development using a testosterone-induced BPH rat model. BPH was induced in experimental groups by daily subcutaneous injections of testosterone propionate (TP), for a period of four weeks. Ursolic acid was administrated daily by oral gavage at a dose level of 5mg/kg during the four weeks of TP injections. Animals were sacrificed on the scheduled termination, before prostates were weighed and subjected to histopathological examination. TP and dihydrotestosterone (DHT) levels in the serum and prostate were also measured. BPH-induced animals displayed an increase in prostate weight with increased testosterone and DHT levels in both the serum and prostate. However, ursolic acid treatment resulted in significant reductions in prostate weight and testosterone and DHT levels in both the serum and prostate, compared with BPH-induced animals. Histopathological examination also showed that ursolic acid treatment suppressed TP-induced prostatic hyperplasia. These findings indicate that ursolic acid may effectively inhibit the development of BPH and it may be a useful agent in BPH treatment.

Effect of ursolic acid, a triterpenoid antioxidant, on ultraviolet-B radiation-induced cytotoxicity, lipid peroxidation and DNA damage in human lymphocytes

Exposure to ultraviolet B (UVB, 280–320) radiation induces the formation of reactive oxygen species (ROS) in the biological system. In this study, we examined the protective effect of ursolic acid on UVB-induced lipid peroxidation and oxidative DNA damage with reference to alterations in cellular antioxidant status in human lymphocytes. Series of in vitro tests (hydroxyl radical, superoxide, nitric oxide, DPPH and ABTS radical scavenging assays) demonstrates antioxidant property of ursolic acid in our study. Treatment of lymphocytes with ursolic acid alone (at 10 μg/mL) gave no significant change in cell viability, thiobarbituric acid reactive substances (TBARSs), lipid hydroperoxides (LHPs), % tail DNA and tail moment when compared with normal lymphocytes. UVB-exposure significantly increased TBARS, LHP and % tail DNA, tail moment; decreased % cell viability and antioxidant status in irradiated lymphocytes. Treatment with ursolic acid 30 min prior to UVB-exposure resulted in a significant decline of TBARS, LHP, % tail DNA and tail moment and increased % cell viability as ursolic acid concentration increased. Based on our results we conclude that ursolic acid, a dietary antioxidant, mediates its protective effect through modulation of UVB-induced reactive oxygen species.

Protective Effect of Ursolic Acid Against Myocardial Ischemia Induced by Isoproterenol in Rats

ABSTRACTSustained high levels of circulating catecholamines may induce cardiotoxicity through oxidative mechanisms. Isoproterenol is a synthetic catecholamine with increasing attention owing to this application in cardiology. The aim of the present study was to investigate the cardioprotective effects of ursolic acid against isoproterenol-induced myocardial ischemia. Normal Wistar strain rats were pretreated with UA (20, 40, and 60 mg/kg, s.c.) for 7 days and then intoxicated with isoproterenol (ISO, 85 mg/kg, s.c. for 2 consecutive days). Hearts were excised from the experimental animals and assessed for the activities of cardiac markers [alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK)], the levels of lipid peroxide products [thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (HPs), and conjugated dienes (CDs)], myeloperoxidase (MPO), lipid profiles [total cholesterol (TC), free cholesterol, ester cholesterol, triglycerides (TG), free fatty acids (FFAs), and phospholipids (PLs)], and membrane-bound enzymes (total ATPase, Na+K+ATPase, Ca2+ATPase, and Mg2+ATPase). In ISO-treated group, shrinkage of cardiac markers and elevated lipid peroxidation with compromised lipid profiles in the heart where accompanied by the decreased activities of membrane-bound enzymes. The prior administration of UA significantly (p < 0.05) prevented the isoproterenol-induced alterations and restored the enzymes to near normal. These findings indicate the cardioprotective activities of UA during isoproterenol-induced myocardial ischemia.

Protective effect of ursolic acid on ethanol-mediated experimental liver damage in rats

Ursolic acid is a triterpenoid that exists in nature and is the major component of some traditional medicinal herbs. In this study, ursolic acid has been evaluated for its hepatoprotective effect against chronic ethanol-mediated toxicity in rats. Ethanol administration (7.9 g/kg/day) for 60 days resulted in increased oxidative stress, decreased antioxidant defense and liver injury. It also negatively affected the serum total protein, albumin and A/G ratio. Subsequent to the experimental induction of toxicity (i.e. after the initial period of 30 days) ursolic acid treatment performed by coadministering ursolic acid (10, 20 and 40 mg/kg body weight) for 30 days along with the daily dose of ethanol. While this treatment causing a significant improvement in body weight, food intake and serum protein levels, it decreases serum aminotransferase activities (aspartate aminotransferase and alanine aminotransferase) and total bilirubin levels. Ursolic acid improved the antioxidant status of alcoholic rats, which is evaluated by the decreased levels of lipid peroxidation markers in plasma (thiobarbituric acid reactive substances and lipid hydroperoxides) and increased levels of circulatory antioxidants such as reduced glutathione, ascorbic acid and α-tocopherol. Histopathological observations were also in correlation with the biochemical parameters. The activity of ursolic acid (20 mg/kg) compares well with silymarin, a known hepatoprotective drug, and seems to be better in certain parameters. The protective effect of ursolic acid is probably related to its antioxidant activities.