AKR1B1 inhibition using NARI-29-an Epalrestat analogue-alleviates Doxorubicin-induced cardiotoxicity via modulating Calcium/CaMKII/MuRF-1 axis.

The clinical use of doxorubicin (Dox) is narrowed due to its carbonyl reduction to doxorubicinol (Doxol) implicating resistance and cardiotoxicity. Hence, in the present study we have evaluated the cardioprotective effect of AKR1B1 (or aldose reductase, AR) inhibitor NARI-29 (epalrestat (EPS) analogue) and its effect in the Dox-modulated calcium/CaMKII/MuRF1 axis. Initially, the breast cancer patient survival associated with AKR1B1 expression was calculated using Kaplan Meier-plotter (KM-plotter). Further, breast cancer, cardiomyoblast (H9c2), and macrophage (RAW 264.7) cell lines were used to establish the in vitro combination effect of NARI-29 and Dox. To develop the cardiotoxicity model, mice were given Dox 2.5 mg/kg (i.p.), biweekly. The effect of AKR1B1 inhibition using NARI-29 on molecular and cardiac functional changes was measured using echocardiography, fluorescence-imaging, ELISA, immunoblotting, flowcytometry, High-Performance Liquid Chromatography with Fluorescence Detection (HPLC-FD) and cytokine-bead array methods. The bioinformatics data suggested that a high expression of AKR1B1 is associated with significantly low survival of breast cancer patients undergoing chemotherapy; hence, it could be a target for chemo-sensitization and chemo-prevention. Further, in vitro studies showed that AKR1B1 inhibition with NARI-29 has increased the accumulation and sensitized Dox to breast cancer cell lines. However, treatment with NARI-29 has alleviated the Dox-induced toxicity to cardiomyocytes and decreased the secretion of inflammatory cytokines from RAW 264.7 cells. In vivo studies revealed that the NARI-29 (25 and 50 mg/kg) has prevented the functional, histological, biochemical, and molecular alterations induced by Dox treatment. Moreover, we have shown that NARI-29 has prevented the carbonyl reduction of Dox to Doxol in the mouse heart, which reduced the calcium overload, prevented phosphorylation of CaMKII, and reduced the expression of MuRF1 to protect from cardiac injury and apoptosis. Hence in conclusion, AKR1B1 inhibitor NARI-29 could be used as an adjuvant therapeutic agent with Dox to prevent cardiotoxicity and synergize anti-breast cancer activity.

[Elucidation and Application of Novel Action of Therapeutic Agents for Diabetic Neuropathy].

Epalrestat is the only aldose reductase inhibitor that is currently available for diabetic peripheral neuropathy. Oxidative stress impairs endothelial cells, thereby leading to numerous pathological conditions. Increasing antioxidative ability is important to prevent cellular toxicity induced by reactive oxygen species. Epalrestat increases antioxidant defense factors such as glutathione and γ-glutamylcysteine ligase in vascular endothelial cells through activation of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2). This increases suppression of oxidative stress-induced cellular toxicity. Cadmium is an industrial and environmental pollutant that targets the vascular endothelium. The vascular system is critically affected by cadmium toxicity. Therapeutic treatment against cadmium toxicity is chelation therapy that promotes metal excretion; however, cadmium chelators can cause renal toxicity. Therefore, safe and efficient therapeutic agents are required. Epalrestat suppresses cadmium-induced cytotoxicity in vascular endothelial cells through activation of Nrf2. In addition, epalrestat affects the intracellular levels of cadmium, cadmium transporter Zrt-Irt-like protein 8 (ZIP8), and metallothionein (MT). The upregulation of ZIP8 and MT may be involved in the suppression of cadmium-induced cytotoxicity by epalrestat. Drug repurposing is a new strategy for drug discovery in which the pharmacological action of existing medicines whose safety and pharmacokinetics have already been confirmed clinically and whose use has been approved is examined comprehensively at the molecular level. The results can be applied to the development of existing drugs for use as medicines for the treatment of other diseases. This review provides useful findings for future expansion of indications as research leading to drug repurposing of epalrestat.

5-(4-hydroxy-3-dimethoxybenzylidene)-rhodanine (RD-1)-improved mitochondrial function prevents anxiety- and depressive-like states induced by chronic corticosterone injections in mice.

Most current pharmacologic antidepressant treatments target monoaminergic systems confronts some problems such as low rate of remission and high risk for relapse indicating new therapeutic strategy is urgently need. Evidences showed that impairments in mitochondrial function were associated with the pathogenesis of mood disorders and improvement in its function may be a novel therapeutic choice. In the present study, effects of 5-(4-hydroxy-3-dimethoxybenzylidene)-2-thioxo-4-thiazolidinone (RD-1) were investigated in mice model of depression/anxiety induced by corticosterone (20 mg/kg) subcutaneously repeated injections in 5-week male BALB/c mice. Our results showed that five weeks of corticosterone administration induced anxiety/depressive-like behavioral changes, including decreased central activities in open field test, increased the immobility time in forced swimming test and the latency in the novelty-suppressed feeding test, as well as reduced bodyweight. Results showed that oral administration with RD-1 at the doses of 25, 50, and 100 mg/kg for five weeks significantly improved the anxiety/depressive-like behavioral changes induced by corticosterone. In glucose metabolism analysis by photon emission computed tomography/-computed tomography (PET/CT) imaging, corticosterone significantly deactivated the prefrontal cortex (PFC), temporal lobe and hippocampus. RD-1 treatment obviously improved the energy metabolism in the involved brain regions. In primary cultured hippocampal neuron, corticosterone reduced speed of anterograde transport, yet speed of retrograde transport was increased. Furthermore, RD-1 enhanced the mitochondrial anterograde transport to supply energy for the neurotransmitter release. In conclusion, RD-1 prevents anxiety/depressive-like behavior of mice induced by corticosterone repeated injections with novel mechanism of improvement in the mitochondrial function.

Hypertensive cardiac remodeling effects of lignan extracts from Eucommia ulmoides Oliv. bark--a famous traditional Chinese medicine.

The lignan extracts from the tree bark of Eucommia ulmoides Oliv., a famous traditional Chinese medicine, have been demonstrated to have inhibitory effects on aldose reductase activity in spontaneously hypertensive rat myocardium. This study was aimed to investigate the hypertensive cardiac remodeling effects of the lignan extracts together with epalrestat. Ten-week-old male spontaneously hypertensive rats were randomly divided into three groups (n = 12, each) and administered 100 mg/kg/d of captopril (angiotensin converting enzyme inhibitor), 100 mg/kg/d of epalrestat (aldose reductase inhibitor) or 300 mg/kg/d of lignan extracts by gavage for 16 weeks. Sex-, age-, and number-matched normotensive Wistar Kyoto rats with spontaneously hypertensive rats were treated with distilled water (vehicle) as controls. Systolic blood pressures were measured periodically. Echocardiography examination was taken when rats were 24 weeks old. We found that both captopril and lignan extracts lowered blood pressure, and inhibited aldose reductase activity similarly to epalrestat. Echocardiography examination and histomorphometry indices were improved in all treated groups (p < 0.05). Therefore, lignan extracts could prevent hypertensive cardiac remodeling, which is likely related to aldose reductase inhibition.

Effects of lignans extracted from Eucommia ulmoides and aldose reductase inhibitor epalrestat on hypertensive vascular remodeling.

AIM OF THE STUDY: To investigate the effects of lignans extracted from Eucommia ulmoides and epalrestat on vascular remodeling in spontaneously hypertensive rats. MATERIALS AND METHODS: Ten-week-old male spontaneously hypertensive rats were randomly divided into 3 groups (12 rats each group), and treated orally with 100 mg/kg/d of captopril (an angiotensin-converting enzyme inhibitor), 100 mg/kg/d of epalrestat (an aldose reductase inhibitor) and 300 mg/kg/d of lignans by gavage daily for 16 weeks, respectively. Sex-, age-, and number-matched spontaneously hypertensive rats and normotensive Wistar Kyoto rats, were treated with distilled water (vehicle) as controls. The rats were weighed weekly. Mean arterial blood pressure and heart rate were measured periodically by non-invasive blood pressure monitoring. They were sacrificed at the end of experiment (26-week-old). Superior mesenteric artery and aorta were isolated for determination of histomorphometry and the expression of aldose reductase by immunohistochemistry. RESULTS: Captopril and lignans, but not epalrestat, decreased mean arterial blood pressure in spontaneously hypertensive rats. Vascular remodeling was improved in all three treated groups by histomorphometry. CONCLUSIONS: Both lignans and epalrestat reversed hypertensive vascular remodeling. Aldose reductase played a vital role in the pathologic process of hypertensive vascular remodeling rather than elevation of blood pressure. These data suggested that aldose reductase could be a new therapeutic target for the treatment of cardiovascular diseases.

Identification of (beta-carboxyethyl)-rhodanine derivatives exhibiting peroxisome proliferator-activated receptor gamma activity.

We applied an improved virtual screening scheme combining ligand-centric and receptor-centric methods for the identification of a new series of PPARgamma agonists known as (beta-carboxyethyl)-rhodanine derivatives which include a thiazolidin-based core structure, 2-thioxo-thiazolidine-4-one. An in vitro assay confirmed the nanomolar binding affinity in one of the (beta-carboxyethyl)-rhodanine derivatives, SP1818. It showed a PPARgamma agonistic activity similar to that of a known PPARgamma drug, pioglitazone, in a cell-based transactivation assay. Furthermore, the structure-activity relationships of the rhodanine derivatives were investigated through comparative molecular field analysis. We also characterized the inconsistency between the in vitro binding affinity and cell-based transactivation ability by using a set of property-based molecular descriptors. The binding mode analysis provided new insight concerning their agonistic effect on PPARgamma.

Aldo-keto reductase family 1 member B10 promotes cell survival by regulating lipid synthesis and eliminating carbonyls.

Aldo-keto reductase family 1 member B10 (AKR1B10) is primarily expressed in the normal human colon and small intestine but overexpressed in liver and lung cancer. Our previous studies have shown that AKR1B10 mediates the ubiquitin-dependent degradation of acetyl-CoA carboxylase-alpha. In this study, we demonstrate that AKR1B10 is critical to cell survival. In human colon carcinoma cells (HCT-8) and lung carcinoma cells (NCI-H460), small-interfering RNA-induced AKR1B10 silencing resulted in caspase-3-mediated apoptosis. In these cells, the total and subspecies of cellular lipids, particularly of phospholipids, were decreased by more than 50%, concomitant with 2-3-fold increase in reactive oxygen species, mitochondrial cytochrome c efflux, and caspase-3 cleavage. AKR1B10 silencing also increased the levels of alpha,beta-unsaturated carbonyls, leading to the 2-3-fold increase of cellular lipid peroxides. Supplementing the HCT-8 cells with palmitic acid (80 mum), the end product of fatty acid synthesis, partially rescued the apoptosis induced by AKR1B10 silencing, whereas exposing the HCT-8 cells to epalrestat, an AKR1B10 inhibitor, led to more than 2-fold elevation of the intracellular lipid peroxides, resulting in apoptosis. These data suggest that AKR1B10 affects cell survival through modulating lipid synthesis, mitochondrial function, and oxidative status, as well as carbonyl levels, being an important cell survival protein.

Inhibitory activities of prenylated flavonoids from Sophora flavescens against aldose reductase and generation of advanced glycation endproducts.

Important targets for the prevention and treatment of diabetic complications include aldose reductase (AR) inhibitors (ARIs) and inhibitors of advanced glycation endproduct (AGE) formation. Here we evaluate the inhibitory activities of prenylated flavonoids isolated from Sophora flavescens, a traditional herbal medicine, on rat lens AR (RLAR), human recombinant AR (HRAR) and AGE formation. Among the tested compounds, two prenylated chalcones--desmethylanhydroicaritin (1) and 8-lavandulylkaempferol (2)--along with five prenylated flavanones--kurarinol (8), kurarinone (9), (2S)-2'-methoxykurarinone (10), (2S)-3beta,7,4'-trihydroxy-5-methoxy-8-(gamma,gamma-dimethylally)-flavanone (11), and kushenol E (13) were potent inhibitors of RLAR, with IC50 values of 0.95, 3.80, 2.13, 2.99, 3.77, 3.63 and 7.74 microM, respectively, compared with quercetin (IC50 7.73 microM). In the HRAR assay, most of the prenylated flavonoids tested showed marked inhibitory activity compared with quercetin (IC50 2.54 microM). In particular, all tested prenylated flavonols, such as desmethylanhydroicaritin (1, IC50 0.45 microM), 8-lavandulylkaempferol (2, IC50 0.79 microM) and kushenol C (3, IC50 0.85 microM), as well as a prenylated chalcone, kuraridin (5, IC50 0.27 microM), and a prenylated flavanone, (2S)-7,4'-dihydroxy-5-methoxy-8-(gamma,gamma-dimethylally)-flavanone (12, IC50 0.37 microM), showed significant inhibitory activities compared with the potent AR inhibitor epalrestat (IC50 0.28 microM). Interestingly, prenylated flavonoids 1 (IC50 104.3 microg mL(-1)), 2 (IC50 132.1 microg mL(-1)), 3 (IC50 84.6 microg mL(-1)) and 11 (IC50 261.0 microg mL(-1)), which harbour a 3-hydroxyl group, also possessed good inhibitory activity toward AGE formation compared with the positive control aminoguanidine (IC50 115.7 microg mL(-1)). Thus, S. flavescens and its prenylated flavonoids inhibit the processes that underlie diabetic complications and related diseases and may therefore have therapeutic benefit.

The synthesis and SAR of rhodanines as novel class C beta-lactamase inhibitors.

Beta-lactam antibiotics such as the cephalosporins and penicillins have diminished clinical effectiveness due to the hydrolytic activity of diverse beta-lactamases, especially those in molecular classes A and C. A structure activity relationship (SAR) study of a high-throughput screening lead resulted in the discovery of a potent and selective non-beta-lactam inhibitor of class C beta-lactamases.