Kidney Aldose Research Articles

Evaluation of benzaldehyde derivatives as being bovine kidney aldose reductase inhibitors

Aldoz redüktaz (AR), poliol yolunda glikozdan sorbitol üretimini katalize eder ve insülinden bağımsız dokularda anormal sorbitol agregasyonuna neden olan, retinopati, nöropati ve nefropati gibi bazı problemler yaratan kritik bir enzimdir. AR inhibisyonunun bu yan etkileri azaltmak için uygun bir yaklaşım olduğu gösterilmiştir. Mevcut çalışma, literatüre yeni AR inhibitörlerini tanıtmayı amaçlamıştır. Bu amaçla AR inhibitörleri olarak benzaldehitler incelenmiştir. İlk olarak sığır böbreğinden homojenat hazırlanmış, ardından inhibisyon çalışmaları yapılmıştır. Çalışılan bütün benzaldehit türevlerinin AR'yi inhibe ettiği bulundu. 0.23 ve 1.37 µM IC50 değerlerine sahip olan türev 3 ve 6'nın inhibitör aktivitesi, standart inhibitör sorbinilden daha yüksek olduğu tespit edildi. In vitro inhibisyon çalışmalarından sonra, tahmini bağlanma enerjileri ve türevlerin enzime bağlanma modları moleküler docking ile tahmin edildi. Bileşik 3, -8,61 kcal/mol'lük bir maksimum yerleştirme puanı sergiledi. Sonuç olarak, bu bileşikler, özellikle bileşik 3, diyabetik komplikasyonların tedavisinde veya önlenmesinde yeni ilaç aday moleküllerinin sentezi için yol gösterici moleküller olabilir.

Bazı İlaç ve Metallerin Keçi (Capra aegagrus hircus) Böbreğinde Aldoz Redüktaz ve Sorbitol Dehidrogenaz Enzimleri Üzerine Etkilerinin Araştırılması

The effects of some antibiotics and metals on goat (Capra aegagrus hircus) kidney aldose reductase (AR) and sorbitol dehydrogenase (SDH) activities were examined. For drugs and metals that exhibit inhibitory effect, Ki constants were calculated and inhibition types were determined by using Lineweaver-Burk curves. In our study, the highest inhibition showed ceftriaxone antibiotic in AR enzyme with an IC50 value of 0.0274 mM. More potent AR inhibitors can be synthesized from the ceftriaxone compound. This compound is followed by amikacin sulfate and ciproflaksasin compounds with IC50 values of 0.061 and 0.25 mM, respectively. The highest inhibition of metals showed Co+2 ion with IC50 value 0.000445 mM. This metal is followed by Fe+2 and Zn+2 with IC50 values of 0.0286 and 0.084 mM, respectively. In SDH enzyme, the highest inhibition showed rifamycin sodium antibiotic with an IC50 value of 0.016 mM. More potent SDH inhibitors can be synthesized from the rifamycin sodium compound. This compound is followed by ceftriaxone and cefuroxime compounds with IC50 values of 0.025 and 0.16 mM, respectively. The highest inhibition of metals showed Co+2 ion with IC50 value 0.00044 mM. This metal is followed by Fe+2 and Zn+2 with IC50 values of 0.009 and 0.16 mM, respectively.

Inhibition of aldose reductase activity by Cannabis sativa chemotypes extracts with high content of cannabidiol or cannabigerol

Aldose reductase (ALR2) is a key enzyme involved in diabetic complications and the search for new aldose reductase inhibitors (ARIs) is currently very important. The synthetic ARIs are often associated with deleterious side effects and medicinal and edible plants, containing compounds with aldose reductase inhibitory activity, could be useful for prevention and therapy of diabetic complications. Non-psychotropic phytocannabinoids exert multiple pharmacological effects with therapeutic potential in many diseases such as inflammation, cancer, diabetes. Here, we have investigated the inhibitory effects of extracts and their fractions from two Cannabis sativa L. chemotypes with high content of cannabidiol (CBD)/cannabidiolic acid (CBDA) and cannabigerol (CBG)/cannabigerolic acid (CBGA), respectively, on human recombinant and pig kidney aldose reductase activity in vitro.A molecular docking study was performed to evaluate the interaction of these cannabinoids with the active site of ALR2 compared to known ARIs.The extracts showed significant dose-dependent aldose reductase inhibitory activity (>70%) and higher than fractions. The inhibitory activity of the fractions was greater for acidic cannabinoid-rich fractions. Comparative molecular docking results have shown a higher stability of the ALR2-cannabinoid acids complex than the other inhibitors. The extracts of Cannabis with high content of non-psychotropic cannabinoids CBD/CBDA or CBG/CBGA significantly inhibit aldose reductase activity. These results may have some relevance for the possible use of C. sativa chemotypes based preparations as aldose reductase inhibitors.

Inhibition behaviours of some phenolic acids on rat kidney aldose reductase enzyme: an in vitro study

Aldose reductase (AR) inhibitors have vital importance in the treatment and prevention of diabetic complications. In this study, rat kidney AR was purified 19.34-fold with a yield of 3.49% and a specific activity of 0.88 U/mg using DE-52 Cellulose anion exchange chromatography, gel filtration chromatography and 2′5′ ADP Sepharose-4B affinity chromatography, respectively. After purification, the in vitro inhibition effects of some phenolic acids (tannic acid, chlorogenic acid, sinapic acid, protocatechuic acid, 4-hydroxybenzoic acid, p-coumaric acid, ferulic acid, vanillic acid, syringic acid, α-resorcylic acid, 3-hydroxybenzoic acid and gallic acid) were investigated on purified enzyme. We determined IC50, Ki values and inhibition types of these phenolic acids. As a result, tannic and chlorogenic acid had a strong inhibition effect. On the other hand, gallic acid had a weak inhibition effect. In this study, all phenolic acids except for chlorogenic acid and p-coumaric acid showed non-competitive inhibition effects on rat kidney AR.

Evaluation of effect of alcoholic extract of heartwood of Pterocarpus marsupium on in vitro antioxidant, anti-glycation, sorbitol accumulation and inhibition of aldose reductase activity

Rising popularity of phytomedicines in various diseased conditions have strengthened the significance of plant-research and evaluation of phytoextracts in clinical manifestations. Pterocarpus marsupium Roxb., a medicinal plant, known for its anti-oxidant and anti-diabetic activity is a rich source of phytochemicals with antihyperglycemic and antihyperlipidemic activities. However, its possible role in diabetic complications is not evaluated yet. The present study explores the possible role of alcoholic extract of heartwood of P. marsupium in the treatment of long-term diabetic complications. The alcoholic extract of P. marsupium was evaluated for advanced glycation-end-products formation, erythrocyte sorbitol accumulation and rat kidney aldose reductase enzyme inhibition at the concentration of 25–400 μg/ml using in-vitro bioassays. Also the phytoextract at the concentration of 10–320 μg/ml was evaluated for its antioxidant potential by in-vitro antioxidant assays which includes, determination of total phenol content; reducing power assay; nitric oxide scavenging activity; superoxide radical scavenging activity; total antioxidant capacity; total flavonoid content; DPPH scavenging activity; and hydrogen peroxide scavenging activity.The alcoholic extract of P. marsupium across varying concentrations showed inhibitory effect as evident by IC50 on advanced glycation-end-products formation (55.39 μg/ml), sorbitol accumulation (151.00 μg/ml) and rat kidney aldose reductase (195.88 μg/ml). The phytoextract also exhibited high phenolic and flavonoid contents with promising antioxidant potential against the antioxidant assays evaluated. The present investigation suggests that the phytoextract showed prominent antioxidant, antiglycation property and, inhibited accumulation of sorbitol and ALR enzyme, thus promising a beneficial role in reducing/delaying diabetic complications.

Aldose Reductase Inhibitory Potential of Several Thiazolyl-thiazolidine- 2,4-Diones

Hyperglycemia has been shown to be the major risk factor responsible for the systemic complications that are the cause of morbidity and mortality in patients with diabetes. The elevated glucose concentration in blood, activates several pathways such as polyol pathway, PKC pathway, hexosamine pathway and plays an important role not only in cataract but also in the pathogenesis of diabetic complications such as neuropathy, nephropathy and retinopathy. The activation of polyol pathway through aldose reductase enzyme leads to accumulate sorbitol in tissues during diabetic stage. Accumulation of sorbitol causes diabetic complications such as cataract, kidney disease. Inhibition of aldose reductase enzyme activity would be an effective treatment of diabetic complications. In the present study, 21 thiazolyl-2,4- thiazolidinediones (TZDs) (compounds 1-21) were tested for their probable inhibitory ability on kidney aldose reductase enzyme. The enzyme activity was determined spectrophotometrically by monitoring NADPH oxidation which accompanies the reduction of D -L-glyceraldehyde which is used as substrate. The inhibition study was performed merely by using 10-4 M concentration of each drug and IC50 values of compounds 1-6, 16-21 were studied. 10-4, 10-5 and 10-6M concentrations were performed for calculating IC50 values. Compound 1 (5-((2, 4-dichlorothiazol-5-yl) methylene) thiazolidine-2, 4-dione) is showed the greatest inhibition capacity with the rate 91.11%. TZD-derivatives which have the compound numbers 2, 5, 16 and 20 are followed the compound 1 with the inhibition capacities of 77.50%, 81.31%, 77.36% and 78.97%, respectively. All the remaining TZD-derivatives are showed inhibitory activity between the rates 4.00 - 76.58 %. Keywords: Thiazolyl-2, 4-thiazolidinediones, Aldose reductase, Enzyme, Inhibition, Diabetes, Polyol pathway

Evaluation of rat kidney aldose reductase inhibitory activity of some N-acetyl dehydroalanine derivatives

Aldose reductase (AR) is an enzyme that catalyzes the conversion of glucose to sorbitol, which is in turn converted to fructose by sorbitol dehydrogenase. Increased AR activity has been implicated in the pathogenesis of diabetic complications such as neuropathy, nephropathy, retinopathy, and cataract. Inhibitors of AR thus seem to have the potential to prevent or treat diabetic complications. At present, however, side effects and/or insufficient pharmacokinetic profiles have made most of the drug candidates undesirable. In this study, the synthesis (l–o) and ARI activity of 15 N-acetyl dehydroalanine derivatives (a–o) are described. The synthesized compounds mainly contained aliphatic and aromatic side chains. The insertion of ethyl and chloro propyl side chains were shown to be more effective than the rest of the compounds. Between the synthesized compounds N-ethyl (b) and N-propylchloride (h) derivatives showed the best ARI activities.

Anti-Diabetic Activity of a Leaf Extract Prepared fromSalacia reticulatain Mice

The effects of a water extract prepared from the leaves of Salacia reticulata on the absorption of sugars in normal and type 1 diabetic mice were investigated. The simultaneous oral administration of the extract at a dose of 1.0 mg/mouse with maltose or sucrose inhibited the postprandial elevation of the plasma glucose and insulin levels and intestinal alpha-glucosidase activities in mice. In addition, the supply of a 0.01% solution of the extract as drinking water prevented the elevation of the plasma glucose level and intestinal alpha-glucosidase activities in type 1 diabetic mice. This treatment also prevented the elevation of the plasma, pancreatic, and kidney lipid peroxide levels, lowering of the plasma insulin level, and elevation of the kidney aldose reductase activities in diabetic mice. These results suggest that the water extract of the leaves of S. reticulata could be a beneficial food material for the prevention of diabetes and obesity because of its multiple effects.

The inhibitory effects of thiazolyl-2,4 thiazolidinedione compounds on the rat kidney aldose reductase enzyme

Aldoz redüktaz enzimi glukozun sorbitole indirgenmesi reaksiyonunda anahtar rol oynamaktadır. Sorbitolün birikimi diyabette, diyabetik katarakt, retinopati, nöropati ve nefropati gibi komplikasyonlara neden olmaktadır. Aldoz redüktaz inhibitörlerinin dokularda sorbitol birikimini önlediği gösterilmiştir. Aldoz redüktaz enziminin inhibisyonunun farmakolojik profilini geliştirmek amacı ile çok sayıda bileşik geliştirilmiştir. Bu çalışmada, tiyazolil-2,4-tiyazolidindion serilerinin (Ia-f, IIa-f and IIIa-f) aldoz redüktaz inhibitör aktiviteleri test edilmiştir. Substitüe-tiyazolil-tiyazolidindion türevlerinin çok az düzeyde inhibitör aktiviteleri olduğu tespit edilmiştir

Prostaglandin F2 Synthase Activities of Aldo-Keto Reductase 1B1, 1B3 and 1B7

Here, we show that three enzymes belonging to the 1B group of the aldo-keto reductase (AKR) superfamily, i.e., human placental aldose reductase (AKR1B1), mouse kidney aldose reductase (AKR1B3) and mouse vas deferens protein (AKR1B7), catalyse the reduction of prostaglandin (PG) H(2), a common intermediate of various prostanoids, to form PGF(2alpha) in the presence of NADPH. AKR1B1, AKR1B3 and AKR1B7 displayed higher affinities for PGH(2) (K(m) = 1.9, 9.3 and 3.8 microM, respectively) and V(max) values (26, 53 and 44 nmol/min/mg protein, respectively) than did the human lung PGF(2alpha) synthase (AKR1C3; 18 microM and 4 nmol/min/mg protein, respectively). The PGF(2alpha) synthase activity of AKR1B1 and AKR1B3 was efficiently inhibited by two AKR inhibitors, tolrestat (K(i) = 3.6 and 0.26 microM, respectively) and sorbinil (K(i) = 21.7 and 0.89 microM, respectively), in a non-competitive or mixed-type manner, whereas that of AKR1B7 was not sensitive to these inhibitors (K(i) = 9.2 and 18 mM, respectively). These data provide a molecular basis for investigating novel functional roles for AKR1B members and PGF(2alpha) as mediators of physiological and pathological processes in mammalian organisms.

Synthesis and biological activity of some new flavonyl-2,4-thiazolidinediones

A new series of flavonyl-2,4-thiazolidinediones ( Va– c, VIa– c) was prepared by Knoevenagel reaction. The synthesized compounds were tested for their ability to inhibit rat kidney aldose reductase (AR) and for their insulinotropic activities in INS-1 cells. Compound Vb was able to increase insulin release in the presence of 5.6 mmol/l glucose. Compounds VIa– c displayed moderate to high AR inhibitory activity levels. Particularly, compound VIa showed the highest AR inhibitory activity (86.57%).

Preliminary evaluation of rat kidney aldose reductase inhibitory activity of 2-phenylindole derivatives: affiliation to antioxidant activity

Diabetic complications including nephropathy, neuropathy, and cataract are leading causes of end-stage renal diseases and neurological disorders. Aldose reductase (AR), the rate-limiting enzyme of the polyol pathway, catalyzes the reduction of glucose to sorbitol via NADPH. Excessive accumulation of intracellular sorbitol found in various tissues of diabetic animals and in cells cultured under high glucose conditions has been proposed to be an important factor for the pathogenesis of diabetic complications. Indole ring–containing AR inhibitors have received considerable attention as potential treatments for diabetic complications. However, these agents have not achieved worldwide use because of limited efficacy or unacceptable adverse effects. In this study, a series of 2-phenylindole derivatives were evaluated via an in vitro spectrophotometric assay for their ability to inhibit rat kidney AR. In addition, the antioxidant and AR inhibitory activities of the compounds under study were compared.

Screening and evaluation of rat kidney aldose reductase inhibitory activity of some pyridazine derivatives

Aldose reductase (AR) is an enzyme that catalyzes the conversion of glucose to sorbitol, which is in turn converted to fructose by sorbitol dehydrogenase. The increased glucose flux through this metabolic pathway has been linked to the development of diabetic complications such as neuropathy, nephropathy, retinopathy, and cataract. Inhibitors of AR thus seem to have the potential to prevent or treat diabetic complications. AR inhibitors belong to different chemical classes, one of which comprises pyridazinone analogues. At present, however, side effects and/or insufficient pharmacokinetic profiles have made most of the drug candidates undesirable. We evaluated a series of 2H-pyridazine-3-one and 6-chloropyridazine analogues via an in vitro spectrophotometric assay for their ability to inhibit rat kidney AR. The study showed that the introduction of a pyrazole ring on pyridazinone led to a marked decrease in AR inhibitory potency. Moreover, introduction of an acetic acid side chain on 2H-pyridazine-3-one and 6-chloropyridazine did not improve the AR inhibitory activity, which was an unexpected result. On the basis of preliminary AR inhibitory screening results on 2H-pyridazine-3-one and 6-chloropyridazine derivatives, we embarked on the synthesis of more derivatives to discover more active molecules.

Rational design of an indolebutanoic acid derivative as a novel aldose reductase inhibitor based on docking and 3D QSAR studies of phenethylamine derivatives.

A series of 45 phenethylamine derivatives were synthesized and evaluated for their inhibitory activity against pig kidney aldose reductase (ALR2, EC 1.1.1.21). Their IC(50) values ranged from 400 microM to 24 microM. The binding modes of compounds at the active site of ALR2 were examined using flexible docking. The results indicated that phenethylamine derivatives nicely fit into the active pocket of ALR2 by forming various hydrogen bonding and hydrophobic interactions. 3D-QSAR analysis was also conducted using FlexX-docked alignment of the compounds. The best prediction was obtained by CoMSIA combined with hydrophobic and hydrogen bond donor/acceptor field (q(2) = 0.557, r(2) = 0.934). A new derivative, 4-oxo-4-(4-hydroxyindole)butanoic acid, was designed, taking into account the CoMSIA field and the binding mode derived by FlexX docking. This rationally designed compound exhibits an ALR2 inhibition with an IC(50) value of 7.4 microM, which compares favorably to that of a well-known ALR2 inhibitor, tolrestat (IC(50) = 16 microM) and represents a potency approximately 240-fold higher than that of an original phenethylamine lead compound, YUA001.

YUA001, a novel aldose reductase inhibitor isolated from alkalophilic Corynebacterium sp. YUA25. II. Chemical modification and biological activity.

A series of novel N-substituted tyramine (2-p-hydroxyphenylethylamine) derivatives (1 to approximately 11) were synthesized and evaluated for their inhibitory activity against pig kidney aldose reductase (EC 1, 1, 1, 21). Of these compounds, N-2-p-hydroxyphenylethyl maleamic acid (10) exhibits the strongest aldose reductase inhibitory activity, which is 22 times more potent than that of YUA001.

NADPH-dependent reductases in dog thyroid: Comparison of a third enzyme “glyceral hyde reductase” to dog thyroid aldehyde reductase

The increased incidence of thyroiditis reported to occur in diabetes has also been observed in long-term galactose-fed dogs where it is reduced by the administration of aldose reductase inhibitors. Since this suggests that thyroidal changes are limned to the abnormal accuuulation of sugar aleobols (polyols), present studies were conducted to confirm the presence of aldose and aldehyde reductases in dog thyroid through isolation and characterization. Aldose and aldehyde reductases were isolated from dog thyroid by a series of chromatographic steps which included gel filtration on Sephadex G100, af alty chromatography on Matrex Gel Orange A and chromatofocusiog on Mono P. A third, labile NADPH-reductase was partially purified by gel filtration on Sephadex G100, affinity chromatography on Matrex Green A and bydroxylapatite chromatography on 1310-GEL HT. The kinetic properties of aldose and aldehyde reductases and their susceptibility to inhibition by allose reductase inhibitors are similar to those of dog kidney aldose and aldehyde reductases. However, the levels of aldose reductase present in thyroid are extremely low compared to the levels of aldehyde reductase. A third NADPH-depaldent reductase, tentatively identified as glyceraldebyde reductase, is also present in dog thyroid. This novel enzyme utilizes NADPH to reduce DL-glyceraldebyde and is clearly distinct from the other aldo-koto reductases in molecular weight, substrate amity, inhibition by aldose reductase inhibitors and immumological properties. In summary aldose reductase, aldehyde reductase and a third novel glyceraldebyde reductase, all of which can utilize glyceraldebyde as substrate, have been identified and characterized in dog thyroid. Only aldose and aldéhyde reductases, which can catalyze the production of polyols and were inhibited by aldose reductase inhibitors, appear to be linked to thyroiditis.

Purification of human and rat kidney aldose reductase.

In the present study we report on a rapid two-step affinity chromatographic procedure to purify aldose reductase from human and rat kidney papilla and inner medulla. This enzyme, which is responsible for sorbitol formation in the kidney, was purified 145-fold from rat and 76-fold from human kidneys by consecutive Blue Sepharose and Matrex Orange chromatography. SDS-PAGE showed a single band of 38 kD for the human enzyme and a doublet of similar molecular weight for the rat kidney aldose reductase. The enzyme was characterized by substrate specificity and kinetic constants found identical to that of other organs purified previously.

Human kidney aldose and aldehyde reductases

Mounting experimental evidence links increased aldose reductase activity with diabetes-related kidney functional changes. To investigate the interrelationship of NADPH-dependent reductases in the human kidney, both aldose reductase and aldehyde reductase were purified from human kidney by a series of chromatographic procedures, including gel filtration on Sephadex G-100, affinity chromatography on Matrex Gel Orange A, and chromatofocusing on Mono P. Each purified enzyme appeared as a single band on polyacrylamide gel after electrophoresis or isoelectric focusing. Aldose reductase has a pI of 5.7 and apparent molecular weight of 37 kDa, calculated from SDS-polyacrylamide gel electrophoresis, while aldehyde reductase has a pI of 5.2 and molecular weight of 39 kDa. Similar molecular weights were also obtained by gel filtration, indicating that both aldose and aldehyde reductases are present as monomers in the human kidney. Aldehyde reductase is primarily localized in the cortex, while the medulla contains aldose reductase. Both enzymes displayed properties consistent with the general characteristics of aldose and aldehyde reductases obtained from either rat or dog kidney. Purified aldose reductase utilizes aldose sugars such as D-xylose, D-glucose, and D-galactose as substrates while aldehyde reductase preferentially reduces D-glucuronate and oxidizes L-gulonate to D-glucuronate. Despite the lower apparent affinity of aldehyde reductase for aldose sugars (∼20- to 100-fold less) both enzymes reduced D-xylose, D-glucose, and D-galactose to their respective sugar alcohols in in vitro incubation studies where the generated sugar alcohols were identified by gas chromatography. Both enzymes were also inhibited by aldose reductase inhibitors. Of the compounds investigated, the carboxylic acids Ponalrestat and FK 366 displayed greater selectivity for inhibiting aldose reductase, whereas the hydantoins sorbinil and Al 1576 displayed more equal inhibition of both enzymes.

Structure determination of N-terminal-blocked peptide from hog kidney aldose 1-epimerase by tandem mass spectrometry.

The blocked-N-terminal structure of hog kidney aldose 1-epimerase (mutarotase, EC 5.1.3.3) was determined to be Ac-Val-Ser-Val-Thr-Arg-Ser-Val-Phe-Gly-Asp... by a coupling of conventional methods (enzymatic digestion, amino acid analysis, and Edman sequencing) and tandem mass spectrometry. The side-chain fragmentations observed in the high-energy product ion spectra gave unambiguous sequence information about the arginine-containing N-terminal structure.

Rat kidney aldose reductase and aldehyde reductase and polyol production in rat kidney

Mounting evidence indicates that aldose reductase catalyzed reduction of excess glucose to sorbitol initiates the onset of certain diabetic complications. However, the kidney contains a large amount of aldehyde reductase, another NADPH-dependent reductase. The study was designed to assess the importance of these reductases to sugar alcohol (polyol) production in the kidney. To study the ability to reduce aldoses to polyols, both aldose and aldehyde reductases were purified from rat kidneys. Incubation studies with purified enzymes clearly demonstrated the polyol formation by both enzymes. Galactose feeding induced polyol accumulation in both medulla and cortex of the rat kidney. Al 1576, a potent inhibitor of both enzymes, reduced this polyol accumulation in both cortex and medulla, while the selective inhibitors Ponalrestat or FK 366 resulted in greater inhibition in medulla than cortex. These results suggest that kidney polyols may be generated by both aldose and aldehyde reductases and that aldehyde reductase contributes to polyol production in the kidney cortex, the predominant site of diabetes-linked kidney lesions.