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.

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.

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.

Association of C(-106)T Polymorphism in Aldose Reductase Gene with Diabetic Retinopathy in Chinese Patients with Type 2 Diabetes Mellitus

Objective To identify the possible association between C（-106）T polymorphism of the aldose reductase （ALR） gene and diabetic retinopathy （DR） in a cohort of Chinese patients with type 2 diabetes mellitus （T2DM）. Methods From November 2009 to September 2010, patients with T2DM were recruited and assigned to DR group or diabetic without retinopathy （DWR） group according to the duration of diabetes and the grading of 7-field fundus color photographs of both eyes. Genotypes of the C（-106）T polymorphism （rs759853） in ALR gene were analyzed using the MassARRAY genotyping system and an association study was performed. Results A total of 268 T2DM patients （129 in the DR group and 139 in the DWR group） were included in this study. No statistically significant differences were observed between the 2 groups in the age of diabetes onset （P=0.10） and gender （P=0.78）. The success rate of genotyping for the study subjects was 99.6% （267/268）, with one case of failure in the DR group. The frequencies of the T allele in the C（-106）T polymorphism were 16.0% （41/256） in the DR group and 19.4% （54/278） in the DWR group （P=0.36）. There was no signit^cant difference in the C（-106）T genotypes between the 2 groups （P=0.40）. Compared with the wild-type genotype, odds ratio （OR） for the risk of DR was 0.7 （95% CI, 0.38-1.3） for the heterozygous CT genotype and 0.76 （95% CI, 0.18-3.25） for the homozygous TT genotype. The risk of DR was positively associated with microalbuminuria （OR=4.61; 95% CI, 2.34-9.05） and insulin therapy （OR=3.43; 95% CI, 1.94-6.09）. Conclusions Microalbuminuria and insulin therapy are associated with the risk of DR in Chinese patients with T2DM. C（-106）T polymorphism of the ALR gene may not be significantly associated with DR in Chinese patients with T2DM.

Diallyl sulfide protects against N-nitrosodiethylamine-induced liver tumorigenesis:Role of aldose reductase

AIM: To evaluate the protective effect of diallyl sulfide (DAS) against N-nitrosodiethylamine (NDEA)-induced liver carcinogenesis.METHODS: Male Wistar rats received either NDEA or NDEA together with DAS as protection.Liver energy metabolism was assessed in terms of lactate,pyruvate,lactate/pyruvate,ATP levels,lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G6PD) activities.In addition,membrane disintegration of the liver cells was evaluated by measuring lipid-peroxidation products,measured as malondialdehyde (MDA); nitric oxide (NO) levels; glucose-6-phosphatase (G6Pase),catalase (CAT) and superoxide dismutase (SOD) activities.Liver DNA level,glutathione-S-transferase (GST) and cytochrome c oxidase activities were used as DNA fragmentation indices.Aldose reductase (AR) activity was measured as an index for cancer cells resistant to chemotherapy and histopathological examination was performed on liver sections from different groups.RESULTS: NDEA significantly disturbed liver functions and most of the aforementioned indices.Treatment with DAS significantly restored liver functions and hepatocellular integrity; improved parameters of energy metabolism and suppressed free-radical generation.CONCLUSION: We provide evidence that DAS exerts a protective role on liver functions and tissue integrity in face of enhanced tumorigenesis caused by NDEA,as well as improving cancer-cell sensitivity to chemotherapy.This is mediated through combating oxidative stress of free radicals,improving the energy metabolic state of the cell,and enhancing the activity of G6Pase,GST and AR enzymes.

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.

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.

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 ...

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.

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.

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.

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.

Polymorphisms and functions of the aldose reductase gene 5' regulatory region in Chinese patients with type 2 diabetes mellitus

Objective To screen the 5’ regulatory region of the aldose reductase (AR) gene for genetic variabilities causing changes in protein expression and affecting the promoter function. Methods The screenings were carried out by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). All SSCP variants were submitted for DNA sequencing and inserted into the plasmid chloromycetin acetyl transferase (CAT) enhancer vector. The constructs were used to transfect Hela cells,and CAT assays were performed to assess promoter activity. Gel mobility shift and footprinting assays were also performed to determine the interaction between the DNA and nuclear proteins. Results Two polymorphisms, C(-106)T and C(-12)G, were identified in the regulatory region in 123 Chinese control subjects and 145 patients with type 2 diabetes mellitus. The frequencies of genotypes WT/WT, WT/C(-12)G and WT/C(-106)T were not significantly different between the subjects and patients. In the patients with and without retinopathy, frequencies of WT/C(-106)T were 31.5% and 17.5% (P【0.05) respectively, and the frequencies of WT/C(-12)G were 10.5% and 2.5% (P】0.05) respectively. The total frequency of WT/C(-12)G and WT/C(-106)T in patients with retinopathy was 41.8%, significantly higher than that (20.0%) in patients without retinopathy (P【0.025). The relative transcription activities of the wild-type, the C(-12)G and the C(-106)T were 15.7%, 31.0% and 32.2%, respectively. The results of DNA-protein interaction assays showed that these variations did not change the binding site of DNA with trans-acting factors. Conclusion The polymorphisms C(-12)G and C(-106)T strongly associated with diabetic retinopathy in the Chinese population have been identified in the regulatory region of the aldose reductase gene.

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.

醛糖还原酶AKR1B1调控甲型流感病毒复制机制的初步研究

醛糖还原酶AKR1B1属于醛酮还原酶家族,是一种NADPH依赖性酶,可催化还原亲水性和疏水性醛。本实验室前期实验发现AKR1B1可以抑制流感病毒复制。为了探究醛糖还原酶AKR1B1调控流感病毒复制的具体机制,本研究通过siRNA干扰下调A549细胞中AKR1B1基因的表达后,经荧光定量RT-PCR(RT-qPCR)检测细胞内AKR1B1 m RNA的转录水平;通过western blot检测siRNA干扰后细胞内AKR1B1蛋白的表达水平;采用噬斑滴定法检测过表达及干扰AKR1B1后对流感病毒滴度的影响;通过western blot检测干扰AKR1B1表达后对细胞内病毒蛋白表达量的影响及甲型流感病毒A/WSN/33(H1N1)(简写为WSN)感染过程中对内源AKR1B1蛋白表达量的影响;采用激光共聚焦试验检测干扰AKR1B1表达对流感病毒NP蛋白核转运的影响;利用双荧光素酶报告系统检测过表达AKR1B1对流感病毒聚合酶活性的影响。RT-qPCR检测结果显示si_AKR1B1_671和si_AKR1B1_721均能极显著下调A549细胞中AKR1B1基因mRNA的转录水平,与对照组相比分别下降95.62%和85.10%(P<0.001),且不影响细胞活力;western blot检测结果显示si_AKR1B1_671能极显著降低细胞中AKR1B1蛋白的表达量(P<0.001),干扰AKR1B1能够增加细胞内病毒蛋白HA、PB2、NP、M1和NS1的表达量;噬斑滴定结果显示,与对照组相比,干扰AKR1B1表达能显著增加流感病毒WSN的病毒滴度,于感染后24 h和48 h病毒滴度分别上升了4.39倍(P<0.01)和5.53倍(P<0.001);与对照组相比,过表达AKR1B1后,流感病毒滴度于感染后24 h和48 h分别下降了62.59%(P<0.01)和82.78%(P<0.001);激光共聚焦试验结果显示,干扰AKR1B1表达不影响流感病毒的入核和出核阶段;Western blot检测结果显示,在流感病毒WSN感染过程中,细胞内源AKR1B1蛋白的表达量较为稳定,不受病毒感染的影响;双荧光素酶报告试验结果显示,与对照组相比,过表达AKR1B1后流感病毒的聚合酶活性下降了26.24%(P<0.001)。上述结果首次表明,醛糖还原酶AKR1B1通过抑制流感病毒聚合酶活性抑制流感病毒复制,干扰AKR1B1蛋白表达对流感病毒NP蛋白的入核和出核均无影响,并且流感病毒感染不影响细胞内源性AKR1B1的表达。本研究初步探究了宿主因子AKR1B1参与流感病毒复制的分子机制,为进一步了解流感病毒的复制调控提供了实验数据。

新型醛糖还原酶抑制1-乙酰基-1H-吲哚-3-乙酸酯的合成及其抑制活性

醛糖还原酶抑制剂(ARIs)抑制多元醇途径的醛糖还原酶是治疗糖尿病并发症的重要策略。以2-氯苯甲酸为起始原料,在碱性条件下经铜催化,与甘氨酸反应生成氯代邻羧基苯基甘氨酸,再与乙酸酐反应,生成N-乙酰基邻羧基苯甲酸。然后在吡啶催化下合环,生成1-乙酰基-^(1)H-吲哚-3-乙酸酯(AIA),总收率为79.0%,纯度为99.0%。通过^(1)H NMR、^(13)C NMR和MS(ESI)对其结构进行表征,并对该化合物的的醛糖还原酶抑制活性进行测定,IC 50=9.4×10^(-2)μM。