Astragalin attenuates diabetic cataracts via inhibiting aldose reductase activity in rats

AIM:To investigate the aldose reductase(AR)inhibition capacity of astragalin(AST)against streptozoticin-induced diabetic cataracts(DCs)in rats.METHODS:Ex vivo investigations were conducted by treating the lens of a goat placed for 72h in artificial aqueous humor(AAH)of pH 7.8 at room temperature with cataract-causing substance(55 mmol/L of galactose)and in vivo studies were performed on rats via induction with streptozotocin.AST was administered at different dose levels and scrutinize for DC activity.RESULTS:In diabetic rats,AST improved the body weight,blood insulin,and glucose as well as the levels of galactitol in a dose-dependent way,other biochemical parameters i.e.inflammatory mediators and cytokines,and also suppress AR activity.The level of the antioxidant parameters such as superoxide dismutase(SOD),catalase(CAT),and glutathione(GSH)activity were also altered on a diabetic lens after the administration of the AST.CONCLUSION:AST protects against lens opacification to avoid cataracts and polyols formation,indicating that it could be used as a potential therapeutic agent for diabetes.

Evaluation of in vitro aldose reductase inhibitory potential of different fraction of Hybanthus enneaspermus Linn F.Muell

Objective:To evaluate the aldose reductase inhibitory(ARI)activity of different fractions of Hybanthus enneaspermus for potential use in diabetic cataract.Methods:Total phenol and flavonoid content of different fractions was determined.ARI activity of different fractions in rat lens was investigated in vitro.Results:The results showed significant level of phenolic and flavonoid content in ethyl acetate fraction[total phenol(212.15±0.79 mg/g),total flavonoid(39.11±2.27mg/g)]and aqueous fraction[total phenol(140.62±0.57mg/g),total flavonoid(26.07±1.49 mg/g)]as compared with the chloroform fraction[total phenol(68.56±0.51mg/g),total flavonoid(13.41±0.82mg/g)]and petrolium ether fraction[total phenol(36.68±0.43mg/g),total flavonoid(11.55±1.06mg/g)].There was a significant difference in the ARI activity of each fraction,and it was found to be the highest in ethyl acetate fraction[IC_(50)(49.26±1.76μg/mL)]followed by aqueous extract[IC_(50)(70.83±2.82μg/mL)]and it was least in the petroleum ether fraction[IC_(50)(118.89±0.71μg/mL)].Chloroform fraction showed moderate activity[IC_(50)(98.52±1.80μg/mL)].Conclusions:Different fractions showed significanct amount of ARI activity,where in ethyl acetate fraction it was found to be maximum which may be due to its high phenolic and flavonoid content.The extract after further evaluation may be used in the treatment of diabetic cataract.

Inhibitory effect of two Indian medicinal plants on aldose reductase of rat lens in vitro

Objective:To assesse the inhibitor) effect of alcoholic extract of two Indian medicinal plants namely Ceasalpinia digyna Rottler and.Alangium lamarckii Thwaits on aldose reductase（AR） of rat lens.Methods:Rats lens were enucleated through posterior approach and their homogenate was prepared and centrifuged to obtain a clear supernatant for the determination of AR activity and protein content.Results:The alcoholic extract of Ceasalpirda digyna and Alangium lamarckii had a potent inhibitory effect on the lens AR enzyme.The IC50 values of alcoholic extract of the selected plants were calculated and were（46.29±11.17） and（106.00±5.11）μg/mL,respectively. Quercetin was used as a positive control and its IC50 value was（2.95±1.53）μg/mL.Conclusions:Thus,it is concluded that alcoholic extracts of the selected plant exhibit significant inhibitory effects on AR in the rat lens in vitro.

Analysis of apigenin in <i>Blumea balsamifera</i>Linn DC. and its inhibitory activity against aldose reductase in rat lens

To investigate the therapeutic potentials of na- tural sources, stepwise polarity fractions of Blumea balsamifera were tested for their ability to inhibit aldose reductase (AR) activity in rat lenses. Of these, the ethyl acetate (EtOAc) fraction exhibited a unique AR inhibitory activity (IC50 value, 0.11 μg/mL). Apigenin was identified from the active EtOAc fraction and exhibited high AR inhibitory activity (IC50 value, 4.03 μM). The content of apigenin was measured in B. balsamifera (0.47 mg/g) by HPLC/UV analysis. Our result suggests that B. balsamifera could be a useful natural source for the development of a novel AR inhibitory agent against diabetic complications.

INHIBITION OF RAT LENS ALDOSE REDUCTASE BY QUERCETAGETIN AND PATULETIN

In this paper the results of inhibition of the Aldose reductase(AR) activity on Wistar rat lens by Quercetagetin extracted from Tagetes erects Linn and by Patuletin extracted from Tagetes patula Linn are reported.Quercetagetin inhibited AR of the rat lens by 93.9% at 10^(-4)M, 76.0% at 10^(-5)M and 13.3% at 10^(-6)M. Patuletin inhibited AR of the rat lens by 100% at 10^(-1)M, 80% at 10^(-5)M and 22.7% at 10^(-6)M respectively. The results show that these two flavones are lens AR Inhibitors, but further ...

Reducing host aldose reductase activity promotes neuronal differentiation of transplanted neural stem cells at spinal cord injury sites and facilitates locomotion recovery

Neural stem cell(NSC)transplantation is a promising strategy for replacing lost neurons following spinal cord injury.However,the survival and differentiation of transplanted NSCs is limited,possibly owing to the neurotoxic inflammatory microenvironment.Because of the important role of glucose metabolism in M1/M2 polarization of microglia/macrophages,we hypothesized that altering the phenotype of microglia/macrophages by regulating the activity of aldose reductase(AR),a key enzyme in the polyol pathway of glucose metabolism,would provide a more beneficial microenvironment for NSC survival and differentiation.Here,we reveal that inhibition of host AR promoted the polarization of microglia/macrophages toward the M2 phenotype in lesioned spinal cord injuries.M2 macrophages promoted the differentiation of NSCs into neurons in vitro.Transplantation of NSCs into injured spinal cords either deficient in AR or treated with the AR inhibitor sorbinil promoted the survival and neuronal differentiation of NSCs at the injured spinal cord site and contributed to locomotor functional recovery.Our findings suggest that inhibition of host AR activity is beneficial in enhancing the survival and neuronal differentiation of transplanted NSCs and shows potential as a treatment of spinal cord injury.

Potential utility of aldose reductase-deficient Schwann cells IKARS1 for the study of axonal degeneration and regeneration

Diabetic peripheral neuropathy（DPN）is one of the most common and intractable complications of diabetes mellitus.Its irritating symptoms,such as paresthesia,hyperalgesia and allodynia,can be causes of insomnia and depression;whereas its progression to more advanced stages can result in serious consequences,such as lower limb amputations and lethal arrhythmias.

Inhibitory Effects of Different Extractions of Salvia deserta Schang on Human Aldose Reductase

[Objectives] To explore whether there are natural substances that inhibit human aldose reductase in different extracts of Salvia deserta Schang.[Methods] The inhibitory activities of human aldose reductase from 28 extracts were screened.[Results] The methanol extract of roots of Salvia deserta Schang had the strongest inhibitory effect on human aldose reductase.[Conclusions] It was confirmed that Salvia deserta Schang has inhibitory effect on human aldose reductase.

Repression of Polyol Pathway Activity by Hemidesmus indicus var.pubescens R.Br.Linn Root Extract,an Aldose Reductase Inhibitor:An In Silico and Ex Vivo Study

Development of diabetic cataract is mainly associated with the accumulation of sorbitol via the polyol pathway through the action of Aldose reductase(AR).Hence,AR inhibitors are considered as potential agents in the management of diabetic cataract.This study explored the AR inhibition potential of Hemidesmus indicus var.pubescens root extract by in silico and ex vivo methods.Molecular docking studies(Auto Dock tool)betweenβ-sitosterol,hemidesminine,hemidesmin-1,hemidesmin-2,and AR showed thatβ-sitosterol(−10.2 kcal/mol)and hemidesmin-2(−8.07 kcal/mol)had the strongest affinity to AR enzyme.Ex vivo studies were performed by incubating isolated goat lenses in artificial aqueous humor using galactose(55 mM)as cataract inducing agent at room temperature(pH 7.8)for 72 h.After treatment with Vitamin E acetate−100μg/mL(standard)and test extract(500 and 1000μg/mL)separately,the estimation of biochemical markers showed inhibition of lens AR activity and decreased sorbitol levels.Additionally,extract also normalized the levels of antioxidant markers like SOD,CAT,GSH.Our results showed evidence that H.indicus var.pubescens root was able to prevent cataract by prevention of opacification and formation of polyols that underlines its potential as a possible therapeutic agent against diabetic complications.

Inhibition Effects of Salvianolic Acid M and Rosmarinic Acid in Salvia deserta Schang on Human Aldose Reductase

[Objectives]This study aimed to investigate the inhibition effects of two chemical constituents in Salvia deserta Schang on human aldose reductase( AR). [Methods]The isolated salvianolic acid M and rosmarinic acid were prepared into different concentrations of solutions for in vitro enzyme kinetics experiments. [Results]Salvianolic acid M and rosmarinic acid had the strongest inhibition effects at the concentration of 1 g/L. [Conclusions]Salvianolic acid M and rosmarinic acid have inhibition effects on human aldose reductase. The IC50 of salvianolic acid M is 0. 79 μg/mL,and that of rosmarinic acid is 1. 13 μg/mL.

Effects of different anesthesiaes on activity of aldose reducetase inRBC and level of plasma nitric oxide in patients undergoing gastric canceroperation

Objective: To investigate the effects of different anesthesiaes on the activity of aldose reductase(AR) in RBC and the levels of plasma nitric oxide(NO) in patients undergoing gastric cancer operation. Methods: Twenty-eight patients undergoing gastric cancer operation were randomly divided into two groups with 14 cases for each. Anesthesia was maintained with 1.5-2.0MAC isoflurane plus epidural block in group Ⅱ. Venous blood samples were collected to measure the AR ctivity in RBC, the levels of plasma NO and glucose. Results: The plasma levels of glucose were increased significantly at 90 min after incision and kept at the high levels till the 1st postoperative day in group Ⅰ(P<0.01 or P<0.05) as compared with those before anesthesia, the changes in group Ⅱ were same as in group Ⅰ(P<0.01),but not on the 1st postoperative day. There was no significant difference between the two groups. The activity of AR in RBC was increased significantly and the level of plasma NO was decreased significantly on the 1st postoperative day in group Ⅰ(P<0.05). In group Ⅱ, AR and NO changed slightly,but these changes were not significant. The extent of change in the activity of AR or the level of NO no the 1st postoperative day in group Ⅱ was less than that in group Ⅰ(P<0.05). Conclusion: Polyol pathway in RBC activated under surgical hyperglycemia while the production of NO is inhibited in patients undergoing gastric cancer operation, which can be effectively attenuated by combined general-epidural anesthesia.

Search of inhibitors of aldose reductase for treatment of diabetic cataracts using machine learning

Purpose:Patients with diabetes mellitus have an elevated chance of developing cataracts,a degenerative visionimpairing condition often needing surgery.The process of the reduction of glucose to sorbitol in the lens of the human eye that causes cataracts is managed by the Aldose Reductase Enzyme(AR),and it is been found that AR inhibitors may mitigate the onset of diabetic cataracts.There exists a large pool of natural and synthetic AR inhibitors that can prevent diabetic complications,and the development of a machine-learning(ML)prediction model may bring new AR inhibitors with better characteristics into clinical use.Methods:Using known AR inhibitors and their chemical-physical descriptors we created the ML model for prediction of new AR inhibitors.The predicted inhibitors were tested by computational docking to the binding site of AR.Results:Using cross-validation in order to find the most accurate ML model,we ended with final cross-validation accuracy of 90%.Computational docking testing of the predicted inhibitors gave a high level of correlation between the ML prediction score and binding free energy.Conclusions:Currently known AR inhibitors are not used yet for patients for several reasons.We think that new predicted AR inhibitors have the potential to possess more favorable characteristics to be successfully implemented after clinical testing.Exploring new inhibitors can improve patient well-being and lower surgical complications all while decreasing long-term medical expenses.

Berberine ameliorates renal injury in streptozotocin-induced diabetic rats by suppression of both oxidative stress and aldose reductase

Background Berberine is one of the main constituents of Coptidis rhizoma （CR） and Cortex phellodendri. In this study, we investigated the beneficial effects of berberine on renal function and its possible mechanisms in rats with diabetic nephropathy （DN）. Methods Male Wistar rats were divided into three groups： normal, diabetic model, and berberine treatment groups. Rats in the diabetic model and berberine treatment groups were induced to diabetes by intraperitonal injection with streptozotocin （STZ）. Glomerular area, glomerular volume, fasting blood glucose （FBG）, blood urea nitrogen （BUN）, serum creatinine （Cr） and urine protein for 24 hours （UP24h） were measured using commercially available kits. Meanwhile, the activity of superoxide dismutase （SOD）, content of malondialdehyde （MDA） in serum, activity of aldose reductase （AR） and the expression of AR mRNA and protein in kidney were detected by different methods. Results The results showed that oral administration of berberine （200 mg·kg^-1·d^-1） significantly ameliorated the ratio of kidney weight to body weight. Glomerular area, glomerular volume, FBG, BUN, Cr and UP24h were significantly decreased in the berberine treatment group compared with the diabetic model group （P〈0.05）. Berberine treatment significantly increased serum SOD activity and decreased the content of MDA compared with diabetic model group （P 〈0.05）. AR activity as well as the expression of AR mRNA and protein in the kidney was markedly decreased in the berberine treatment group compared with diabetic model group （P 〈0.05）. Conclusion These results suggested that berberine could ameliorate renal dysfunction in DN rats through controlling blood glucose, reduction of oxidative stress and inhibition of the activation of the polyol pathway.

Inhibitory effect of eleven herbal extracts on advanced glycation end-products formation and aldose reductase activity

The formation of advanced glycation end-products （AGEs） and aldose reductase （AR） activity have been implicated in the development of diabetic complications. Our study sought to characterize the capacities of eleven herbal extracts against the formation of AGEs and the AR activity. An ultrahigh performance liquid chromatography and tandem mass spectrometry （UPLC-MS/MS） method was used for the detection of AR activity and the screening of AR inhibitors in this research. The amount of sorbitol from each analyte was directly detected using the multiple reaction monitoring mode and the sorbitol level could be reduced via the addition of an inhibitor. Moreover, the BSA/glucose （fructose） system was applied to investigate their inhibitory activities of AGEs formation in glycation model reactions. Compared with other screened herbs used in our study, Flos Sophorae lrnrnaturus and Radix Scutellariae seemed to be more effective on inhibiting the formation of AGEs and AR activity. The inhibiting capacities of herbal extracts against AR activity and AGEs formation may be correlated with the bioactive components of the herbal extracts. The differences were correlated with the amount of polyphenol and flavonoid components. In the study, we have investigated the potential anti-hyperglycemic bioactivity of eleven herbal extracts in vitro, which could provide a reference for further in vivo research in the prevention and treatment of diabetic complications.

Pharmacologically tested aldose reductase inhibitors isolated from plant sources—A concise report

Aldose reductase (AR), a cytosolic, monomeric oxidoreductase, is a key enzyme in the polyol pathway which controls the conversion of glucose to sorbitol. The accumulation of sorbitol by the activation of AR enzymes in lens, retina, and sciatic nerves leads to the cause of diabetic defects resulting in various secondary complications, viz. retinopathy, neuropathy, nephropathy and Alzheimer's disease. Thus, reduction of the polyol pathway flux by AR inhibitors could be a potential therapeutic opening in the treatment and prevention of diabetic complications. At present, the AR inhibitors belong to two different chemical classes. One is the hydantoin derivatives, such as Sorbinil, Dilantin, and Minalrestat, and the other is the carboxylic acid derivatives, such as Epalrestat, Alrestatin, and Tolrestat. However, it is known that most of these synthethic compounds have unacceptable side-effects. Well known medicinal plants like Chrysanthemum indicum, Chrysanthemum morifolium, Prunus mume, Myrcia multiflora, Centella asiatica, and Salacia reticulata, Salacia oblonga, and Salacia chinensis exhibited potent AR inhibitory activity. The present review summarizes the list of plant material, and their isolated phytoconstituents which have been tested for their AR inhibitory activity. This litreature review covers the period to 2011, and a total of 72 plants are listed.

Epalrestat protects against diabetic peripheral neuropathy by alleviating oxidative stress and inhibiting polyol pathway

Epalrestat is a noncompetitive and reversible aldose reductase inhibitor used for the treatment of diabetic neuropathy. This study assumed that epalrestat had a protective effect on diabetic peripheral nerve injury by suppressing the expression of aldose reductase in peripheral nerves of diabetes mellitus rats. The high-fat and high-carbohydrate model rats were established by intraperitoneal injection of streptozotocin. Peripheral neuropathy occurred in these rats after sustaining high blood glucose for 8 weeks. At 12 weeks after streptozotocin injection, rats were intragastrically administered epalrestat 100 mg/kg daily for 6 weeks. Transmission electron microscope revealed that the injuries to myelinated nerve fibers, non-myelinated nerve fibers and Schwann cells of rat sciatic nerves had reduced compared to rats without epalrestat administuation. Western blot assay and immunohistochemical results demonstrated that after intervention with epalrestat, the activities of antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase gradually increased, but aldose reductase protein expression gradually diminished. Results confirmed that epalrestat could protect against diabetic peripheral neuropathy by relieving oxidative stress and suppressing the polyol pathway.

Pathologically relevant aldoses and environmental aldehydes cause cilium disassembly via formyl group-mediated mechanisms

Carbohydrate metabolism disorders(CMDs),such as diabetes,galactosemia,and mannosidosis,cause ciliopathy-like multiorgan defects.However,the mechanistic link of cilia to CMD complications is still poorly understood.Herein,we describe significant cilium disassembly upon treatment of cells with pathologically relevant aldoses rather than the corresponding sugar alcohols.Moreover,environmental aldehydes are able to trigger cilium disassembly by the steric hindrance effect of their formyl groups.Mechanistic studies reveal that aldehydes stimulate extracellular calcium influx across the plasma membrane,which subsequently activates the calmodulin-Aurora A-histone deacetylase 6 pathway to deacetylate axonemal microtubules and triggers cilium disassembly.In vivo experiments further show that Hdac6 knockout mice are resistant to aldehyde-induced disassembly of tracheal cilia and sperm flagella.These findings reveal a previously unrecognized role for formyl group-mediated cilium disassembly in the complications of CMDs.

Diabetes mellitus:An overview on its pharmacological aspects and reported medicinal plants having antidiabetic activity

Diabetes mellitus is not a single disease but is a group of metabolic disorders affecting a huge numlier of population in the world.It is mainly characterized by chronic hyperglycemia,resulting from defects in insulin secretion or insulin action.It is predicated that the number of diabetes person in the world could reach upto 366 million by the year 2030.Even though the cases of diabetes are increasing day by day,except insulin and oral hypoglycemic drugs no other way of treatment has been successfully developed so far.Thus,the objective of the present review is to provide an insight over the pathophysiological and etiological aspects of diabetes mellitus along with the remedies available for this metabolic disorder.The review also contains brief idea about diabetes mellitus and the experimental screening model with their relevant mechanism and significance mainly used nowadays.Alloxan and streptozotocin are mainly used for evaluating the antidiabetic activity of a particular drug.This review contain list of medicinal plants which have been tested for their antidiabetic activity in the alloxan induced diabetic rat model.From the available data in the literature,it was found that plant having antidiabetic activity is mainly due to the presence of the secondary metabolite.Thus,the information provided in this review will help the researchers for the development of an alternative methods rather than insidin and oral hypoglycemic agents for the treatment of diabetes niellitus,which will minimize the complication associated with the diabetes and related disorder.

Efficacy of epalrestat plus α-lipoic acid combination therapy versus monotherapy in patients with diabetic peripheral neuropathy: a meta-analysis of 20 randomized controlled trials

OBJECTIVE： To evaluate the efficacy of α-lipoic acid（ALA） plus epalrestat combination therapy in the treatment of diabetic peripheral neuropathy（DPN）. DATA SOURCES： The electronic databases of Pub Med, Medline, Embase, the Cochrane Library, the Chinese National Knowledge Infrastructure, the Wanfang Database and the Chinese Biomedical Database were used to retrieve relevant studies without language restrictions. The search was conducted from the inception of each database to 7 October 2016. The key terms were（diabetic peripheral neuropathy or diabetic neuropathy or DPN） AND（α-lipoic acid or lipoic acid or thioctic acid） AND epalrestat. DATA SELECTION： All of the eligible studies met the following inclusion criteria：（1） Randomized controlled trials that compared efficacy and safety of epalrestat plus ALA combination therapy versus epalrestat or ALA monotherapy in patients with DPN.（2） The minimum duration of treatment was 2 weeks.（3） The DPN patients were diagnosed using the World Health Organization standardized type 2 diabetes mellitus and DPN criteria.（4） Studies contained at least one measure that could reflect the efficacy of the drug and nerve conduction velocities. Studies in which the control group used epalrestat or ALA combined with other drugs were excluded. Statistical analyses were performed using STATA software for meta-analysis. OUTCOME MEASURES： The primary outcomes were the therapeutic efficacy, median motor nerve conduction velocity（MNCV）, median sensory nerve conduction velocity（SNCV）, peroneal MNCV and peroneal SNCV.RESULTS： Twenty studies with 1894 DPN patients were included, including 864 patients in the ALA plus epalrestat group, 473 in the ALA group and 557 in the epalrestat group. The efficacy of ALA plus epalrestat combination therapy was superior to ALA and epalrestat monotherapies（RR = 1.29, 95% CI： 1.21–1.38; RR = 1.43, 95% CI： 1.34–1.54, respectively）. ALA plus epalrestat combination therapy also significantly improved median MNCV（WMD = 5.41, 95% CI： 2.07–8.75）, median SNCV（WMD = 5.87, 95% CI： 1.52–10.22）, peroneal MNCV（WMD = 5.59, 95% CI： 2.70–8.47） and peroneal SNCV（WMD = 4.57, 95% CI： 2.46–6.68）.CONCLUSION： ALA plus epalrestat combination therapy was superior to ALA and epalrestat monotherapies for clinical efficacy and nerve conduction velocities in patients with DPN.