epalrestat and Diabetes-Mellitus

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.

Topics: Aldehyde Reductase; Antioxidants; Cadmium; Chelating Agents; Diabetes Mellitus; Diabetic Neuropathies; Endothelial Cells; Environmental Pollutants; Glutathione; Humans; Ligases; Metallothionein; NF-E2-Related Factor 2; Reactive Oxygen Species; Rhodanine; Thiazolidines

Diabetes Mellitus (DM) is the fastest growing metabolic disorder affecting about 387 million people across the globe and is estimated to affect 592 million people by year 2030. The search for newer anti-diabetic agents is the foremost need to control the accelerating diabetic population. Several natural and (semi) synthetic chalcones deserve the credit of being potential candidates that act by modulating the therapeutic targets PPAR-γ, DPP-4, α-glucosidase, PTP1B, aldose reductase, and stimulate insulin secretion and tissue sensitivity. In this review, a comprehensive study (from January 1977 to October 2014) of anti-diabetic chalcones, their molecular targets, structure activity relationships (SARs), mechanism of actions (MOAs) and patents have been described. The compounds which showed promising activity and have a well-defined MOAs, SARs must be considered as prototype for the design and development of potential anti-diabetic agents. They should be evaluated critically at all clinical stages to ensure their therapeutic and toxicological profile to meet the demand of diabetics.

Topics: alpha-Glucosidases; Chalcones; Diabetes Mellitus; Glycoside Hydrolase Inhibitors; Humans; Hypoglycemic Agents; Molecular Structure; Structure-Activity Relationship

Topics: Aldehyde Reductase; Arteriosclerosis; Blood Glucose; Diabetes Mellitus; Enzyme Inhibitors; Guanidines; Humans; Hypoglycemic Agents; Insulin Resistance; Rhodanine; Thiazolidines

Topics: Aldehyde Reductase; Animals; Binding Sites; Blood Glucose; Cataract; Chemical Phenomena; Chemistry; Corneal Diseases; Diabetes Complications; Diabetes Mellitus; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Disease Models, Animal; Fluorenes; Galactose; Humans; Hydantoins; Imidazoles; Imidazolidines; Models, Molecular; Naphthalenes; Phthalazines; Rhodanine; Sorbitol; Structure-Activity Relationship; Substrate Specificity; Sugar Alcohol Dehydrogenases; Thiazolidines; Tissue Distribution

In order to study a long-term effect along with adverse action of epalrestat, an aldose reductase inhibitor, a randomized, prospective study was conducted over the period of 3 years at 112 facilities. Six hundred and three diabetic patients with median motor conduction velocity (MCV)>40 m/s, HbA1c<9% were randomly allocated to epalrestat (50 mg/day p.o. ac, t.i.d.) group (E group: n=289, age: 61+/-9.8 y.o.) and a control group (C group: n=305, age: 61+/-9.1 y.o.). MCV was measured once a year for 3 years. MCV (m/s, M+/-S.D.) on baseline, 1 year and 3 years, was 52.0+/-4.5, 52.2+/-4.9, 52.1+/-4.6 in E group and 53.3+/-4.4, 52.4+/-4.2, 52.0+/-4.6 in C group, respectively. After 3 years, difference from the baseline was significant (p<0.0001, E versus C). Among the subjects with HbA1c<7.0%, C group showed marked deterioration of MCV while in E group, there was no significant deterioration (p<0.001). Although, the subjects with pre-proliferative or proliferative retinopathy, there was no difference between E and C groups for 3 years, in subjects with background retinopathy or without retinopathy, deterioration rate of E group was significantly less than that of C group (p<0.0001). Epalrestat was found to prevent deterioration of MCV especially in well-controlled patients without advanced complications. No remarkable side effects serious enough to discontinue the study was observed.

Topics: Age of Onset; Aged; Aldehyde Reductase; Body Mass Index; Diabetes Mellitus; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Enzyme Inhibitors; Female; Glycated Hemoglobin; Humans; Male; Middle Aged; Motor Neurons; Neural Conduction; Prospective Studies; Rhodanine; Thiazolidines

Topics: Action Potentials; Aldehyde Reductase; Diabetes Mellitus; Diabetic Neuropathies; Double-Blind Method; Electric Stimulation; Female; Follow-Up Studies; Humans; Male; Middle Aged; Neural Conduction; Reaction Time; Rhodanine; Thiazolidines

While the mechanism in the pathogenesis of diabetic corneal disease is unclear, aldose reductase has been implicated in corneal disease. The effects of an oral aldose reductase inhibitor (ARI) on the ocular surface of diabetic patients after cataract surgery were studied.. This clinical trial was designed to be randomised, double blinded, and placebo controlled. Pseudophakic patients with diabetes were randomly assigned to treatment with either oral ARI (ONO-2235) (n=12) or placebo (n=9) for 12 weeks. The vital staining of the ocular surface, tear production and clearance, break up time in tears (BUT), corneal and conjunctival sensation, and symptom score before treatments were examined as well as 4, 8, 12 weeks after the administration. Specular microscopic evaluation was also performed.. After a 12 week period of oral ARI administration, fluorescein staining scores (from 2.04 (SD 1.12) to 1.46 (1.18); p=0.016), conjunctival sensation (from 1.15 (0.37) to 1.36 (0.31); p=0.0006), and symptom scores (from 5.38 (1.932) to 4.00 (2.07); p=0.0002) recovered significantly. Fluorescein staining of oral ARI administration also decreased compared with placebo (p=0.017). Rose bengal staining, tear clearance, and corneal sensation were improved although this increase was minor. Tear production, BUT, and specular microscopic evaluation of the corneal epithelium and endothelium did not demonstrate a significant change.. Oral ARI opposes the ocular surface changes caused by diabetes, by recovery of ocular surface sensitivity as demonstrated through an improvement in vital staining.

Topics: Administration, Oral; Aged; Aldehyde Reductase; Cataract Extraction; Conjunctiva; Diabetes Mellitus; Double-Blind Method; Enzyme Inhibitors; Epithelium, Corneal; Female; Fluorescein; Fluorescent Dyes; Humans; Male; Microscopy, Fluorescence; Postoperative Period; Rhodanine; Rose Bengal; Sensation; Tears; Thiazolidines

The mechanism in the pathogenesis of diabetic corneal disease is unclear, but aldose reductase may be involved in the corneal disease. We studied the effects of an aldose reductase inhibitor (ARI) on the ocular surface of diabetic patients. Fourteen aphakic or pseudophakic patients with diabetes were treated with orally administered ONO-2235 (150 mg/day). Corneal sensation, vital staining of ocular surface, and tear production were examined before and 3 months after the administration. After a 3-month period of oral ARI, corneal sensation recovered significantly (from 4.1 +/- 4.8 to 3.0 +/- 3.1 g/mm2; p = 0.015), with parallel improvements in rose bengal and fluorescein staining scores (p < 0.05). Tear break-up time had also improved (p = 0.003). Results of Schirmer's test (p = 0.03) and the cotton-thread test (p = 0.0001) showed significant improvement in tear production. Improvement in the dynamics of tear production may be due to an improvement in corneal sensitivity. An oral ARI can improve corneal epithelial changes caused by diabetes, probably through recovery of corneal sensation and tear production.

Topics: Administration, Oral; Aged; Aldehyde Reductase; Cornea; Corneal Diseases; Diabetes Complications; Diabetes Mellitus; Enzyme Inhibitors; Female; Humans; Male; Middle Aged; Rhodanine; Sensation; Tears; Thiazolidines

Transdermal penetration of therapeutic moieties from topical dosage forms always remains a challenge due to the presence of permeation impeding keratin which should be addressed. The purpose of the study was to formulate quercetin and 4-formyl phenyl boronic acid (QB complex) used for the preparation of nanoethosomal keratolytic gel (EF3-G). The QB complex was confirmed by Fourier transform infrared spectroscopy while skin permeation, viscosity, and epalrestat entrapment efficiency were used for the optimization of nanoethosomal gel. The keratolytic effect of the proposed nanoethosomal gel with urea (QB + EPL + U) was calculated in rat and snake skin. The spherical shape of nanoethosomes was confirmed by scanning electron microscopy. According to the findings of stability studies, viscosity decreases as temperature increases, proving their thermal stability. The negative charge of optimized EF3 with 0.7 PDI proved narrow particle size distribution with homogeneity. Optimized EF3 showed two folds increase of epalrestat permeation in highly keratinized snake skin as compared to rats' skin after 24 h. Antioxidant behaviors of EF3 (QB) > QB complex > quercetin > ascorbic acid proved reduction of oxidative stress in DPPH reduction analysis. Interestingly, the hot plate and cold allodynia test in the diabetic neuropathic rat model reduced 3-fold pain as compared to the diabetic control group which was further confirmed by in vivo biochemical studies even after the eight week. Conclusively, ureal keratolysis, primary dermal irritation index reduction, and improved loading of epalrestat render the nanoethosomal gel (EF3-G) ideal for the treatment of diabetic neuropathic pain.

Topics: Administration, Cutaneous; Animals; Antioxidants; Diabetes Mellitus; Neuralgia; Particle Size; Quercetin; Rats

Starting from the known inhibitory activity of (3-benzoylpyrrol-1-yl)acetic acid (I) and (2-benzoylpyrrol-1-yl)acetic acid (II), a series of 3-aroyl and 2,4-bis-aroyl derivatives (54-75) were synthesized and tested for inhibition of aldose reductase, an enzyme involved in the appearance of diabetic complications. It was found that a number of the tested compounds exhibited considerable activity in the micromolar range. Important structural features for the potent compounds is the presence of substituents with relatively low Hammett sigma values and/or moieties which increase their overall aromatic area. The most active derivative was the [2,4-bis(4-methoxybenzoyl)pyrrol-1-yl]acetic acid (75), with potency favorably compared to known ARIs such as tolrestat, epalrestat, zopolrestat, and fidarestat. Four selected derivatives were also evaluated for their ability to interfere with the oxidative modification of serum albumin in an in vitro experimental glycation model of diabetes mellitus. All of them showed considerable activity, comparable to the known inhibitor trolox. Our results, taken together, indicate that compound 75 combines favorably two biological activities directly connected to a number of pathological conditions related to the chronic diabetes mellitus.

Topics: Acetates; Aldehyde Reductase; Animals; Diabetes Mellitus; Enzyme Inhibitors; Female; Fructose; Male; Monosaccharides; Oxidation-Reduction; Proteins; Pyrroles; Rats; Rats, Inbred F344; Serum Albumin; Structure-Activity Relationship

We examined the effect of fidarestat on the increase in sorbitol content in erythrocytes from healthy volunteers in vitro. Fidarestat inhibited the increase with an IC50 value of 18 nmol/l. A subsequent experiment showed that fidarestat had a similar inhibitory effect on the increase in sorbitol content in erythrocytes from diabetic patients. On the other hand, epalrestat, the only aldose reductase inhibitor used clinically, inhibited increase in sorbitol content at a concentration over 500-fold higher than fidarestat. Although the IC50 value of fidarestat was not affected by fasting plasma glucose, HbA1C, age, aldose reductase content or gender, there was a significant positive relationship between the IC50 value of epalrestat and fasting plasma glucose. In addition, in fidarestat (0.25-2 mg/kg)-treated diabetic rats, the inhibitory rate for erythrocyte sorbitol accumulation was well correlated with that for nerve sorbitol accumulation, which indicates that erythrocyte sorbitol is available for assessing the state of sorbitol pathway flux in target tissue after fidarestat administration. These results suggest that fidarestat potently inhibits the increase in sorbitol pathway flux in diabetic patients independent of various factors and that erythrocyte sorbitol is useful for its estimation.

Topics: Age Factors; Aldehyde Reductase; Animals; Blood Glucose; Body Weight; Diabetes Mellitus; Diabetes Mellitus, Experimental; Dose-Response Relationship, Drug; Enzyme Inhibitors; Erythrocytes; Fasting; Female; Glycated Hemoglobin; Humans; Imidazoles; Imidazolidines; Male; Rats; Rats, Sprague-Dawley; Rhodanine; Sciatic Nerve; Sex Factors; Sorbitol; Thiazolidines

The effects of a high-glucose medium, insulin, and an aldose reductase inhibitor (ONO-2235) on sorbitol accumulation were compared in the human erythrocyte and the rabbit retina, while the effects of epinephrine on in vitro sorbitol accumulation were investigated in the human and rabbit retina. In both erythrocytes and the retina, linear increments of sorbitol accumulation were observed in a dose-dependent manner with 5 to 50 mM glucose. These increments were markedly inhibited by 100 microM ONO-2235 but not by insulin (400 microU/ml). In the presence of 5 mM glucose, a dose-dependent increase of the sorbitol content of the rabbit retina was seen following epinephrine stimulation (0.4-4.0 microM and this was markedly reduced by 100 microM ONO-2235. Moreover, both 50 mM glucose and 4.0 microM epinephrine increased the sorbitol content of the retina from a diabetic patient, and the glucose-induced increment in sorbitol was significantly reduced by 100 microM ONO-2235. Our data suggested that aldose reductase inhibitors might be useful for the treatment of diabetic retinopathy, since the polyol pathway appears to be an important factor in its pathogenesis, and that catecholamines might have some role in the activation of the retinal polyol pathway.

Topics: Aged; Aldehyde Reductase; Animals; Diabetes Mellitus; Epinephrine; Erythrocytes; Fructose; Glucose; Humans; In Vitro Techniques; Insulin; Male; Rabbits; Reference Values; Retina; Rhodanine; Sorbitol; Thiazolidines

The mechanism by which hyperglycaemia leads to diabetic complications has not been fully elucidated. Non-enzymatic glycosylation leads to considerable functional and structural alteration of proteins. Hyperglycaemia also induces changes in intracellular metabolites, particularly in the polyol pathway. Aldose reductase inhibitors, which block the polyol pathway, have been shown to prevent complications in animal models, and this provides the rationale for the large scale trials that are presently being conducted.

Topics: Aldehyde Reductase; Diabetes Complications; Diabetes Mellitus; Glycolysis; Glycosylation; Humans; Hyperglycemia; Imidazoles; Imidazolidines; Naphthalenes; Phthalazines; Rhodanine; Thiazolidines