Oleanolic acid suppresses pentylenetetrazole-induced seizure in vivo.

The aim of this study was to investigate the protective effects of triterpene oleanolic acid on the brain tissue of mice with pentylenetetrazole (PTZ)-induced epileptic seizures. Male Swiss albino mice were randomly separated into five groups as the PTZ, control, and oleanolic acid (10, 30, and 100 mg/kg) groups. PTZ injection was seen to cause significant seizures compared with the control group. Oleanolic acid significantly prolonged the latency to onset of myoclonic jerks and the duration of clonic convulsions, and decreased mean seizure scores following PTZ administration. Pretreatment with oleanolic acid also led to an increase in antioxidant enzyme activity (CAT and AChE) and levels (GSH and SOD) in the brain. The data obtained from this study support oleanolic acid may have anticonvulsant potential in PTZ-induced seizures, prevent oxidative stress and protect against cognitive disturbances. These results may provide useful information for the inclusion of oleanolic acid in epilepsy treatment.

Study Design and Baseline Characteristics of the CARDINAL Trial: A Phase 3 Study of Bardoxolone Methyl in Patients with Alport Syndrome.

INTRODUCTION: Alport syndrome is a rare genetic disorder that affects as many as 60,000 persons in the USA and a total of 103,000 persons (<5 per 10,000) in the European Union [1, 2]. It is the second most common inherited cause of kidney failure and is characterized by progressive loss of kidney function that often leads to end-stage kidney disease. Currently, there are no approved disease-specific agents for therapeutic use. We designed a phase 3 study (CARDINAL; NCT03019185) to evaluate the safety, tolerability, and efficacy of bardoxolone methyl in patients with Alport syndrome. METHODS: The CARDINAL phase 3 study is an international, multicenter, double-blind, placebo-controlled, randomized registrational trial. Eligible patients were of ages 12-70 years with confirmed genetic or histologic diagnosis of Alport syndrome, eGFR 30-90 mL/min/1.73 m2, and urinary albumin to creatinine ratio (UACR) ≤3,500 mg/g. Patients with B-type natriuretic peptide values >200 pg/mL at baseline or with significant cardiovascular histories were excluded. Patients were randomized 1:1 to bardoxolone methyl or placebo, with stratification by baseline UACR. RESULTS: A total of 371 patients were screened, and 157 patients were randomly assigned to receive bardoxolone methyl (n = 77) or placebo (n = 80). The average age at screening was 39.2 years, and 23 (15%) were <18 years of age. Of the randomized population, 146 (93%) had confirmed genetic diagnosis of Alport syndrome, and 62% of patients had X-linked mode of inheritance. Mean baseline eGFR was 62.7 mL/min/1.73 m2, and the geometric mean UACR was 141.0 mg/g. The average annual rate of eGFR decline prior to enrollment in the study was -4.9 mL/min/1.73 m2 despite 78% of the patient population receiving ACE inhibitor (ACEi) or ARB therapy. DISCUSSION/CONCLUSION: CARDINAL is one of the largest interventional, randomized controlled trials in Alport syndrome conducted to date. Despite the use of ACEi or ARB, patients were experiencing significant loss of kidney function prior to study entry.

Saikosaponin D: review on the antitumour effects, toxicity and pharmacokinetics.

CONTEXT: Bupleuri Radix, the dried root of Bupleurum chinense DC and Bupleurum scorzonerifolium Willd (Apiaceae), is an important medicinal herb widely used to treat cancers for hundreds of years in Asian countries. As the most antitumour component but also the main toxic component in Bupleuri Radix, saikosaponin D (SSD) has attracted extensive attention. However, no summary studies have been reported on the antitumour effects, toxicity and pharmacokinetics of this potential natural anticancer substance. OBJECTIVE: To analyse and summarise the existing findings regarding to the antitumour effects, toxicity and pharmacokinetics of SSD. MATERIALS AND METHODS: We collected relevant information published before April 2021 by conducting a search of literature available in various online databases including PubMed, Science Direct, CNKI, Wanfang database and the Chinese Biological Medicine Database. Bupleurum, Bupleuri Radix, saikosaponin, saikosaponin D, tumour, toxicity, and pharmacokinetics were used as the keywords. RESULTS: The antitumour effects of SSD were multi-targeted and can be realised through various mechanisms, including inhibition of proliferation, invasion, metastasis and angiogenesis, as well as induction of cell apoptosis, autophagy, and differentiation. The toxicological effects of SSD mainly included hepatotoxicity, neurotoxicity, haemolysis and cardiotoxicity. Pharmacokinetic studies demonstrated that SSD had the potential to alter the pharmacokinetics of some drugs for its influence on CYPs and P-gp, and the oral bioavailability and actual pharmacodynamic substances in vivo of SSD are still controversial. CONCLUSIONS: SSD is a potentially effective and relatively safe natural antitumour substance, but more research is needed, especially in vivo antitumour effects and pharmacokinetics of the compound.

Bardoxolone methyl: drug development for diabetic kidney disease.

Bardoxolone methyl activates the Keap1/Nrf2 system that plays an important role in defense responses against oxidative stress. Importantly, bardoxolone methyl has demonstrated increases in estimated glomerular filtration rate (eGFR) in patients with diabetic kidney disease (DKD) in clinical studies. However, an overseas Phase 3 study of bardoxolone methyl in patients with stage G4 DKD was prematurely terminated due to an increased risk for heart failure, which was considered to have been caused by early-onset fluid overload. Subsequently, a Japanese Phase 2 study demonstrated, for the first time, that bardoxolone methyl directly improves GFR, which is a true indicator of kidney function, using the inulin clearance method. In Japan, bardoxolone methyl was designated for the treatment of DKD under the Priority Review and Designation (SAKIGAKE Designation) System established by the Ministry of Health, Labour and Welfare. A Japanese Phase 3 study, with endpoints such as a ≥ 30% decrease in eGFR, is currently ongoing to assess the efficacy and safety of bardoxolone methyl in more than 1,000 patients with stages G3 and G4 DKD who have no identified risk factors.

Effect of bardoxolone methyl on the urine albumin-to-creatinine ratio in patients with type 2 diabetes and stage 4 chronic kidney disease.

Bardoxolone methyl attenuates inflammation by inducing nuclear factor erythroid-derived 2-related factor 2 and suppressing nuclear factor κB. The Bardoxolone Methyl Evaluation in Patients With Chronic Kidney Disease and Type 2 Diabetes (BEACON) trial was a phase 3 placebo-controlled, randomized, double-blind, parallel-group, international, multicenter trial in 2185 patients with type 2 diabetes mellitus and stage 4 chronic kidney disease. BEACON was terminated because of safety concerns, largely related to a significant increase in early heart failure events in patients randomized to bardoxolone methyl. Bardoxolone methyl resulted in increased estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio. Herein, we present post hoc analyses characterizing the relation between the urine albumin-to-creatinine ratio and eGFR. The urine albumin-to-creatinine ratio and eGFR were assessed every four weeks through Week 12, followed by assessments every eight weeks thereafter, and 4 weeks after the last dose of bardoxolone methyl was administered. The initial increases in urine albumin-to-creatinine ratio observed in patients randomized to bardoxolone methyl were attenuated after six months. Multivariable regression analysis identified baseline eGFR and eGFR over time as the dominant factors associated with change in the urine albumin-to-creatinine ratio. Relative to placebo, bardoxolone methyl resulted in a significant decrease in albuminuria when indexed to eGFR (least-squared means: -0.035 [95% confidence interval -0.031 to -0.039]). Thus, among patients with type 2 diabetes mellitus and stage 4 chronic kidney disease treated with bardoxolone methyl, changes in albuminuria are directly related to changes in eGFR, challenging the conventional construct that increases in albuminuria universally reflect kidney injury and denote harm.

Oleanolic acid reprograms the liver to protect against hepatotoxicants, but is hepatotoxic at high doses.

Oleanolic acid (OA) is a triterpenoid that exists widely in fruits, vegetables and medicinal herbs. OA is included in some dietary supplements and is used as a complementary and alternative medicine (CAM) in China, India, Asia, the USA and European countries. OA is effective in protecting against various hepatotoxicants, and one of the protective mechanisms is reprogramming the liver to activate the nuclear factor erythroid 2-related factor 2 (Nrf2). OA derivatives, such as CDDO-Im and CDDO-Me, are even more potent Nrf2 activators. OA has recently been shown to also activate the Takeda G-protein-coupled receptor (TGR5). However, whereas a low dose of OA is hepatoprotective, higher doses and long-term use of OA can produce liver injury, characterized by cholestasis. This paradoxical hepatotoxic effect occurs not only for OA, but also for other OA-type triterpenoids. Dose and length of time of OA exposure differentiate the ability of OA to produce hepatoprotection vs hepatotoxicity. Hepatotoxicity produced by herbs is increasingly recognized and is of global concern. Given the appealing nature of OA in dietary supplements and its use as an alternative medicine around the world, as well as the development of OA derivatives (CDDO-Im and CDDO-Me) as therapeutics, it is important to understand not only that they program the liver to protect against hepatotoxic chemicals, but also how they produce hepatotoxicity.

Bardoxolone Methyl Improves Kidney Function in Patients with Chronic Kidney Disease Stage 4 and Type 2 Diabetes: Post-Hoc Analyses from Bardoxolone Methyl Evaluation in Patients with Chronic Kidney Disease and Type 2 Diabetes Study.

BACKGROUND: Increases in measured inulin clearance, measured creatinine clearance, and estimated glomerular filtration rate (eGFR) have been observed with bardoxolone methyl in 7 studies enrolling approximately 2,600 patients with type 2 diabetes (T2D) and chronic kidney disease (CKD). The largest of these studies was Bardoxolone Methyl Evaluation in Patients with Chronic Kidney Disease and Type 2 Diabetes (BEACON), a multinational, randomized, double-blind, placebo-controlled phase 3 trial which enrolled patients with T2D and CKD stage 4. The BEACON trial was terminated after preliminary analyses showed that patients randomized to bardoxolone methyl experienced significantly higher rates of heart failure events. We performed post-hoc analyses to characterize changes in kidney function induced by bardoxolone methyl. METHODS: Patients in -BEACON (n = 2,185) were randomized 1: 1 to receive once-daily bardoxolone methyl (20 mg) or placebo. We compared the effects of bardoxolone methyl and placebo on a post-hoc composite renal endpoint consisting of ≥30% decline from baseline in eGFR, eGFR <15 mL/min/1.73 m2, and end-stage renal disease (ESRD) events (provision of dialysis or kidney transplantation). RESULTS: Consistent with prior studies, patients randomized to bardoxolone methyl experienced mean increases in eGFR that were sustained through study week 48. Moreover, increases in eGFR from baseline were sustained 4 weeks after cessation of treatment. Patients randomized to bardoxolone methyl were significantly less likely to experience the composite renal endpoint (hazards ratio 0.48 [95% CI 0.36-0.64]; p < 0.0001). CONCLUSIONS: Bardoxolone methyl preserves kidney function and may delay the onset of ESRD in patients with T2D and stage 4 CKD.

A New Oleanolic Acid Derivative against CCl4-Induced Hepatic Fibrosis in Rats.

A novel hepatoprotective oleanolic acid derivative, 3-oxours-oleana-9(11), 12-dien-28-oic acid (Oxy-Di-OA), has been reported. In previous studies, we found that Oxy-Di-OA presented the anti-HBV (Hepatitis B Virus) activity (IC50 = 3.13 µg/mL). Remarkably, it is superior to lamivudine in the inhibition of the rebound of the viral replication rate. Furthermore, Oxy-Di-OA showed good performance of anti-HBV activity in vivo. Some studies showed that liver fibrosis may affiliate with HBV gene mutations. In addition, the anti-hepatic fibrosis activity of Oxy-Di-OA has not been studied. Therefore, we evaluated the protective effect of Oxy-Di-OA against carbon tetrachloride (CCl4)-induced liver injury in rats. Daily intraperitoneally administration of Oxy-Di-OA prevented the development of CCl4-induced liver fibrosis, which was evidenced by histological study and immunohistochemical analysis. The entire experimental protocol lasted nine weeks. Oxy-Di-OA significantly suppressed the increases of plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels (p < 0.05). Furthermore, Oxy-Di-OA could prevent expression of transforming growth factor ß1 (TGF-ß1). It is worth noting that the high-dose group Oxy-Di-OA is superior to bifendate in elevating hepatic function. Compared to the model group, Oxy-Di-OA in the high-dose group and low-dose group can significantly reduce the liver and spleen indices (p < 0.05). The acute toxicity test showed that LD50 and a 95% confidence interval (CIs) value of Oxy-Di-OA were 714.83 mg/kg and 639.73-798.73 mg/kg via intraperitoneal injection in mice, respectively. The LD50 value of Oxy-Di-OA exceeded 2000 mg/kg via gavage in mice. In addition, a simple and rapid high performance liquid chromatography-ultraviolet (HPLC-UV) method was developed and validated to study the pharmacokinetic characteristics of the compound. After single-dose oral administration, time to reach peak concentration of Oxy-Di-OA (Cmax = 8.18 ± 0.66 µg/mL) was 10 ± 2.19 h; the elimination half-life and area under the concentration-time curve from t = 0 to the last time of Oxy-Di-OA was 2.19 h and 90.21 µg·h/mL, respectively.

A systematic review of the active saikosaponins and extracts isolated from Radix Bupleuri and their applications.

CONTEXT: Radix Bupleuri has been used in traditional Chinese medicine for over 2000 years with functions of relieving exterior syndrome, clearing heat, regulating liver-qi, and lifting yang-qi. More natural active compounds, especially saikosaponins, have been isolated from Radix Bupleuri, which possess various valuable pharmacological activities. OBJECTIVE: To summarize the current knowledge on pharmacological activities, mechanisms and applications of extracts and saikosaponins isolated from Radix Bupleuri, and obtain new insights for further research and development of Radix Bupleuri. METHODS: PubMed, Web of Science, Science Direct, Research Gate, Academic Journals and Google Scholar were used as information sources through the inclusion of the search terms 'Radix Bupleuri', 'Bupleurum', 'saikosaponins', 'Radix Bupleuri preparation', and their combinations, mainly from the year 2008 to 2016 without language restriction. Clinical preparations containing Radix Bupleuri were collected from official website of China Food and Drug Administration (CFDA). RESULTS AND CONCLUSION: 296 papers were searched and 128 papers were reviewed. A broad spectrum of in vitro and in vivo research has proved that Radix Bupleuri extracts, saikosaponin a, saikosaponin d, saikosaponin c, and saikosaponin b2, exhibit evident anti-inflammatory, antitumor, antiviral, anti-allergic, immunoregulation, and neuroregulation activities mainly through NF-κB, MAPK or other pathways. 15 clinical preparations approved by CFDA remarkably broaden the application of Radix Bupleuri. The main side effect of Radix Bupleuri is liver damage when the dosage is excess, which indicates that the maximum tolerated dose is critical for clinical use of Radix Bupleuri extract and purified compounds.

Bardoxolone methyl in type 2 diabetes and stage 4 chronic kidney disease.

BACKGROUND: Although inhibitors of the renin-angiotensin-aldosterone system can slow the progression of diabetic kidney disease, the residual risk is high. Whether nuclear 1 factor (erythroid-derived 2)-related factor 2 activators further reduce this risk is unknown. METHODS: We randomly assigned 2185 patients with type 2 diabetes mellitus and stage 4 chronic kidney disease (estimated glomerular filtration rate [GFR], 15 to <30 ml per minute per 1.73 m(2) of body-surface area) to bardoxolone methyl, at a daily dose of 20 mg, or placebo. The primary composite outcome was end-stage renal disease (ESRD) or death from cardiovascular causes. RESULTS: The sponsor and the steering committee terminated the trial on the recommendation of the independent data and safety monitoring committee; the median follow-up was 9 months. A total of 69 of 1088 patients (6%) randomly assigned to bardoxolone methyl and 69 of 1097 (6%) randomly assigned to placebo had a primary composite outcome (hazard ratio in the bardoxolone methyl group vs. the placebo group, 0.98; 95% confidence interval [CI], 0.70 to 1.37; P=0.92). In the bardoxolone methyl group, ESRD developed in 43 patients, and 27 patients died from cardiovascular causes; in the placebo group, ESRD developed in 51 patients, and 19 patients died from cardiovascular causes. A total of 96 patients in the bardoxolone methyl group were hospitalized for heart failure or died from heart failure, as compared with 55 in the placebo group (hazard ratio, 1.83; 95% CI, 1.32 to 2.55; P<0.001). Estimated GFR, blood pressure, and the urinary albumin-to-creatinine ratio increased significantly and body weight decreased significantly in the bardoxolone methyl group, as compared with the placebo group. CONCLUSIONS: Among patients with type 2 diabetes mellitus and stage 4 chronic kidney disease, bardoxolone methyl did not reduce the risk of ESRD or death from cardiovascular causes. A higher rate of cardiovascular events with bardoxolone methyl than with placebo prompted termination of the trial. (Funded by Reata Pharmaceuticals; BEACON ClinicalTrials.gov number, NCT01351675.).

Bardoxolone methyl and kidney function in CKD with type 2 diabetes.

BACKGROUND: Chronic kidney disease (CKD) associated with type 2 diabetes is the leading cause of kidney failure, with both inflammation and oxidative stress contributing to disease progression. Bardoxolone methyl, an oral antioxidant inflammation modulator, has shown efficacy in patients with CKD and type 2 diabetes in short-term studies, but longer-term effects and dose response have not been determined. METHODS: In this phase 2, double-blind, randomized, placebo-controlled trial, we assigned 227 adults with CKD (defined as an estimated glomerular filtration rate [GFR] of 20 to 45 ml per minute per 1.73 m(2) of body-surface area) in a 1:1:1:1 ratio to receive placebo or bardoxolone methyl at a target dose of 25, 75, or 150 mg once daily. The primary outcome was the change from baseline in the estimated GFR with bardoxolone methyl, as compared with placebo, at 24 weeks; a secondary outcome was the change at 52 weeks. RESULTS: Patients receiving bardoxolone methyl had significant increases in the mean (±SD) estimated GFR, as compared with placebo, at 24 weeks (with between-group differences per minute per 1.73 m(2) of 8.2±1.5 ml in the 25-mg group, 11.4±1.5 ml in the 75-mg group, and 10.4±1.5 ml in the 150-mg group; P<0.001). The increases were maintained through week 52, with significant differences per minute per 1.73 m(2) of 5.8±1.8 ml, 10.5±1.8 ml, and 9.3±1.9 ml, respectively. Muscle spasms, the most frequent adverse event in the bardoxolone methyl groups, were generally mild and dose-related. Hypomagnesemia, mild increases in alanine aminotransferase levels, and gastrointestinal effects were more common among patients receiving bardoxolone methyl. CONCLUSIONS: Bardoxolone methyl was associated with improvement in the estimated GFR in patients with advanced CKD and type 2 diabetes at 24 weeks. The improvement persisted at 52 weeks, suggesting that bardoxolone methyl may have promise for the treatment of CKD. (Funded by Reata Pharmaceuticals; BEAM ClinicalTrials.gov number, NCT00811889.).

Risk factors for heart failure in patients with type 2 diabetes mellitus and stage 4 chronic kidney disease treated with bardoxolone methyl.

BACKGROUND: A phase 3 randomized clinical trial was designed to test whether bardoxolone methyl, a nuclear factor erythroid-2-related factor 2 (Nrf2) activator, slows progression to end-stage renal disease in patients with stage 4 chronic kidney disease and type 2 diabetes mellitus. The trial was terminated because of an increase in heart failure in the bardoxolone methyl group; many of the events were clinically associated with fluid retention. METHODS AND RESULTS: We randomized 2,185 patients with type 2 diabetes mellitus (T2DM) and stage 4 chronic kidney disease (CKD) (estimated glomerular filtration rate 15 to <30 mL min(-1) 1.73 m(-2)) to once-daily bardoxolone methyl (20 mg) or placebo. We used classification and regression tree analysis to identify baseline factors predictive of heart failure or fluid overload events. Elevated baseline B-type natriuretic peptide and previous hospitalization for heart failure were identified as predictors of heart failure events; bardoxolone methyl increased the risk of heart failure by 60% in patients with these risk factors. For patients without these baseline characteristics, the risk for heart failure events among bardoxolone methyl- and placebo-treated patients was similar (2%). The same risk factors were also identified as predictors of fluid overload and appeared to be related to other serious adverse events. CONCLUSIONS: Bardoxolone methyl contributed to events related to heart failure and/or fluid overload in a subpopulation of susceptible patients with an increased risk for heart failure at baseline. Careful selection of participants and vigilant monitoring of the study drug will be required in any future trials of bardoxolone methyl to mitigate the risk of heart failure and other serious adverse events.

Mechanisms contributing to adverse cardiovascular events in patients with type 2 diabetes mellitus and stage 4 chronic kidney disease treated with bardoxolone methyl.

BACKGROUND: Bardoxolone methyl, an Nrf2-activating and nuclear factor-κB-inhibiting semisynthetic oleanane triterpenoid compound, was evaluated in a phase 3 trial (BEACON) in patients with type 2 diabetes mellitus (T2DM) and stage 4 chronic kidney disease (CKD). The trial was terminated because of an increase in heart failure events in the bardoxolone methyl group, many of which appeared related to fluid retention. Thus, additional analyses were conducted to explain these serious adverse events. METHODS: Patients (n = 2,185) were randomized to receive once-daily bardoxolone methyl (20 mg) or placebo. Twenty-four-hour urine collections were analyzed in a subset of the BEACON population and from a separate, open-label pharmacology study in patients with stage 3b/4 CKD and T2DM administered 20 mg bardoxolone methyl once daily for 56 consecutive days. RESULTS: Bardoxolone-methyl-treated patients in the BEACON substudy had a clinically meaningful reduction in urine volume and sodium excretion at week 4 relative to baseline (p < 0.05), and a separate study revealed that decreased sodium excretion and urine output occurred in some patients with stage 4 CKD but not those with stage 3b CKD. The clinical phenotype of fluid overload and heart failure in BEACON was similar to that observed with endothelin receptor antagonists in advanced CKD patients, and preclinical data demonstrate that bardoxolone methyl modifies endothelin signaling. CONCLUSIONS: The totality of the evidence suggests that through modulation of the endothelin pathway, bardoxolone methyl may pharmacologically promote acute sodium and volume retention and increase blood pressure in patients with more advanced CKD.

The endothelin pathway: a protective or detrimental target of bardoxolone methyl on cardiac function in patients with advanced chronic kidney disease?

Bardoxolone methyl has been reported to cause detrimental cardiovascular events in the terminated BEACON Phase III human clinical trial via modulation of the renal endothelin pathway. However, the effects of bardoxolone methyl administration on the endothelin pathway in the heart are unknown. Our purpose in this perspective is to highlight the distinctive opposing roles of the renal and heart endothelin pathway in cardiac function. Furthermore, we address the need for further investigation in order to determine if bardoxolone methyl has a protective role in cardiac function through the suppression of the endothelin pathway in the heart.

Bardoxolone methyl analogs RTA 405 and dh404 are well tolerated and exhibit efficacy in rodent models of Type 2 diabetes and obesity.

Bardoxolone methyl and related triterpenoids are well tolerated and efficacious in numerous animal models potentially relevant to patients with Type 2 diabetes and chronic kidney disease. These agents enhance glucose control and regulate lipid accumulation in rodent models of diabetes and obesity, and improve renal function, reduce inflammation, and prevent structural injury in models of renal disease. However, a recent study in Zucker diabetic fatty (ZDF) rats noted poor tolerability with the bardoxolone methyl analog RTA 405 within 1 mo after treatment initiation, although this study was confounded in part by the use of an impure RTA 405 batch. To investigate these discordant observations, the present studies were conducted to further characterize triterpenoids in rodent models of diabetes and obesity. A follow-up study was conducted in ZDF rats with two related triterpenoids (RTA 405 and dh404) for 1.5 mo. Consistent with previous rodent experience, and in contrast to the more recent ZDF report, ZDF rats administered RTA 405 or dh404 exhibited no adverse clinical signs, had laboratory values similar to controls, and exhibited no evidence of adverse liver or kidney histopathology. Additionally, RTA 405 was well tolerated in streptozotocin-induced Type 1 diabetic rats and high-fat-diet-induced obese mice. The present results are consistent with the overall published body of data obtained with triterpenoids and provide further evidence that these molecules are well tolerated without adverse effects on hepatobiliary or renal function in rodent models of diabetes and obesity.

Analogs of bardoxolone methyl worsen diabetic nephropathy in rats with additional adverse effects.

Bardoxolone methyl is an antioxidant inflammation modulator acting through induction of Keap1-Nrf2 pathway. Results from a recent phase IIb clinical trial reported that bardoxolone methyl was associated with improvement in the estimated glomerular filtration rate in patients with advanced chronic kidney disease and Type 2 diabetes. However, increases in albuminuria, serum transaminase, and frequency of adverse events were noted. We studied the effect of 3-mo treatment with RTA 405, a synthetic triterpenoid analog of bardoxolone methyl in Zucker diabetic fatty rats with overt Type 2 diabetes. Rats were treated from 3 mo of age with vehicle, RTA 405, ramipril, or RTA 405 plus ramipril. RTA 405 caused severe changes in food intake and diuresis with decline in body weight, worsening of dyslipidemia, and increase in blood pressure. Early elevation in serum transaminase was followed by liver injury. RTA 405 worsened proteinuria, glomerulosclerosis, and tubular damage. Ramipril was renoprotective, but when given with RTA 405 it was not able to limit its worsening effects. These data could be due to degradation products in the drug substance used, as disclosed by the company once the study was concluded. To overcome such a drawback, the company offered to test dh404, a variant of RTA 405, in Zucker diabetic fatty rats. The dh404 did not display beneficial effects on proteinuria, glomerulosclerosis, and interstitial inflammation. Rather, kidneys from three rats receiving dh404 showed the presence of a granulomatous and inflammatory process reminiscent of a pseudotumor. Altogether these data raise serious concerns on the use of bardoxolone analogs in Type 2 diabetic nephropathy.

Bardoxolone methyl decreases megalin and activates nrf2 in the kidney.

Inflammation and oxidative stress are hallmarks and mediators of the progression of CKD. Bardoxolone methyl, a potent activator of the nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated antioxidant and anti-inflammatory response, increases estimated GFR and decreases BUN, serum phosphorus, and uric acid concentrations in patients with moderate to severe CKD. However, it also increases albuminuria, which is associated with inflammation and disease progression. Therefore, we investigated whether this bardoxolone methyl-induced albuminuria may result from the downregulation of megalin, a protein involved in the tubular reabsorption of albumin and lipid-bound proteins. Administration of bardoxolone methyl to cynomolgus monkeys significantly decreased the protein expression of renal tubular megalin, which inversely correlated with the urine albumin-to-creatinine ratio. Moreover, daily oral administration of bardoxolone methyl to monkeys for 1 year did not lead to any adverse effects on renal histopathologic findings but did reduce serum creatinine and BUN, as observed in patients with CKD. Finally, the bardoxolone methyl-induced decrease in megalin corresponded with pharmacologic induction of renal Nrf2 targets, including NAD(P)H:quinone oxidoreductase 1 enzyme activity and glutathione content. This result indicates that Nrf2 may have a role in megalin regulation. In conclusion, these data suggest that the increase in albuminuria that accompanies bardoxolone methyl administration may result, at least in part, from reduced expression of megalin, which seems to occur without adverse effects and with strong induction of Nrf2 targets.

Repeated oral administration of oleanolic acid produces cholestatic liver injury in mice.

Oleanolic acid (OA) is a triterpenoid and a fantastic molecule with many beneficial effects. However, high-doses and long-term use can produce adverse effects. This study aimed to characterize the hepatotoxic potential of OA. Mice were given OA at doses of 100-3,000 µmol/kg (45-1,350 mg/kg), po for 10 days, and the hepatotoxicity was determined by serum biochemistry, histopathology, and toxicity-related gene expression via real-time RT-PCR. Animal body weight loss was evident at OA doses of 1,000 µmol/kg and above. Serum alanine aminotransferase activities were increased in a dose-dependent manner, indicative of hepatotoxicity. Serum total bilirubin concentrations were increased, indicative of cholestasis. OA administration produced dose-dependent pathological lesions to the liver, including inflammation, hepatocellular apoptosis, necrosis, and feathery degeneration indicative of cholestasis. These lesions were evident at OA doses of 500 µmol/kg and above. Real-time RT-PCR revealed that OA produced dose-dependent increases in acute phase proteins (MT-1, Ho-1, Nrf2 and Nqo1), decreases in bile acid synthesis genes (Cyp7a1 and Cyp8b1), and decreases in liver bile acid transporters (Ntcp, Bsep, Oatp1a1, Oatp1b2, and Ostß). Thus, the clinical use of OA and OA-type triterpenoids should balance the beneficial effects and toxicity potentials.