Enzyme Of Polyol Pathway Research Articles

The Role of Aldose Reductase in Polyol Pathway: An Emerging Pharmacological Target in Diabetic Complications and Associated Morbidities.

The expression of aldose reductase leads to a variety of biological and pathological effects. It is a multifunctional enzyme which has a tendency to reduce aldehydes to the corresponding sugar.alcohol. In diabetic conditions, the aldose reductase enzyme converts glucose into sorbitol using nicotinamide adenine dinucleotide phosphate as a cofactor. It is a key enzyme in polyol pathway which is a surrogate course of glucose metabolism. The polyol pathway has a significant impact on the aetiology of complications in individuals with end-stage diabetes. The exorbitant level of sorbitol leads to the accumulation of intracellular reactive oxygen species in diabetic heart, neurons, kidneys, eyes and other vasculatures, leading to many complications and pathogenesis. Recently, the pathophysiological role of aldose reductase has been explored with multifarious perspectives. Research on aldose reductase suggest that besides implying in diabetic complications, the enzyme also turns down the lipid-derived aldehydes as well as their glutathione conjugates. Although aldose reductase has certain lucrative role in detoxification of toxic lipid aldehydes, its overexpression leads to intracellular accumulation of sorbitol which is involved in secondary diabetic complications, such as neuropathy, cataractogenesis, nephropathy, retinopathy and cardiovascular pathogenesis. Osmotic upset and oxidative stress are produced by aldose reductase via the polyol pathway. The inhibition of aldose reductase alters the activation of transcription factors like NF-ƙB. Moreover, in many preclinical studies, aldose reductase inhibitors have been observed to reduce inflammation-related impediments, such as asthma, sepsis and colon cancer, in diabetic subjects. Targeting aldose reductase can bestow a novel cognizance for this primordial enzyme as an ingenious strategy to prevent diabetic complications and associated morbidities. In this review article, the significance of aldose reductase is briefly discussed along with their prospective applications in other afflictions.

Активність ензимів поліольного шляху у нирках щурів за умов різної забезпеченості раціону протеїном і сахарозою

The study examined the activity of enzymes in the polyol pathway and the status of free radical processes in the kidneys of rats subjected to different dietary protein and sucrose levels. It was found that the kidneys of animals consuming a highsucrose diet, irrespective of protein content, exhibited the highest increase in the activity of polyol pathway enzymes, namely aldose reductase and sorbitol dehydrogenase. Consumption of a high-sucrose diet enhances the generation of O2 •- in the kidneys by almost twofold, and hydroxyl radical by over fourfold compared to control indicators. This is accompanied by a twofold increase in the content of TBARS-active products and a threefold increase in the content of carbonyl derivatives of proteins, against the background of a decrease in the content of free thiol groups in proteins. The pronounced generation of hydroxyl radicals, accumulation of TBARS-active products, and reduction in the content of free SH-groups in proteins are characteristic of animals that consumed a high-sucrose diet in the context of dietary protein deficiency. It has been demonstrated that excessive sucrose consumption is a critical factor, influencing the activity of enzymes in the polyol pathway and the intensity of free radical processes. The obtained results may be considered as predisposing factors for disruptions in the structural and functional organization of the kidneys under conditions of nutrient imbalance.

Discovery of a Novel Benzothiadiazine-Based Selective Aldose Reductase Inhibitor as Potential Therapy for Diabetic Peripheral Neuropathy.

Aldose reductase2 (ALR2), an activated enzyme in polyol pathway by hyperglycemia, has long been recognized as one of the most promising targets for diabetic complications especially in diabetic peripheral neuropathy (DPN). However, lots of ALR2 inhibitors showed serious sideeffects due to poor selectivity over aldehyde reductase (ALR1). Herein, we described the discovery of a series of benzothiadiazine acetic acid derivatives as potent and selective inhibitors against ALR2 and evaluation of their anti-DPN activities in vivo. Compound 15c carrying carbonyl group at the 3-position of thiadiazine ring showed high potent inhibition against ALR2 (IC50 = 33.19 nM) and about 16109-fold selectivity for ALR2 over ALR1. Cytotoxicity assays ensured the primary biosafety of 15c. Further pharmacokinetic assay in rats indicated 15c had a good pharmacokinetic feature (T1/2 = 5.60 h, AUC(0-t) = 598.57±216.5 μg/mL*h), which was superior to Epalrestat (T1/2 = 2.23 h, AUC(0-t) = 20.43±3.7 μg/mL*h). Finally, in streptozotocin (STZ)-induced diabetic rat model, 15c significantly increased the nerve conduction velocities (NCVs) of impaired sensory and motor nerve, achieved potent inhibition of D-sorbitol production in the sciatic nerves, and significantly increased the paw withdrawal mechanical threshold (PWMT). Combined the above investigations, we proposed that 15c might represent a promising lead compound for discovery of anti-diabetic peripheral neuropathy drug.

AKR1B1 drives hyperglycemia-induced metabolic reprogramming in MASLD-associated hepatocellular carcinoma

The mechanism behind the progressive pathological alteration in metabolic dysfunction-associated steatotic liver disease/steatohepatitis (MASLD/MASH)-associated hepatocellular carcinoma (HCC) is poorly understood. In the present study, we investigated the role of the polyol pathway enzyme AKR1B1 in metabolic switching associated with MASLD/MASH and in the progression of HCC. AKR1B1 expression was estimated in the tissue and plasma of patients with MASLD/MASH, HCC, and HCC with diabetes mellitus. The role of AKR1B1 in metabolic switching invitro was assessed through media conditioning, lentiviral transfection, and pharmacological probes. A proteomic and metabolomic approach was applied for the in-depth investigation of metabolic pathways. Preclinically, mice were subjected to a high-fructose diet and diethylnitrosamine to investigate the role of AKR1B1 in the hyperglycemia-mediated metabolic switching characteristic of MASLD-HCC. A significant increase in the expression of AKR1B1 was observed in tissue and plasma samples from patients with MASLD/MASH, HCC, and HCC with diabetes mellitus compared to normal samples. Mechanistically, invitro assays revealed that AKR1B1 modulates the Warburg effect, mitochondrial dynamics, the tricarboxylic acid cycle, and lipogenesis to promote hyperglycemia-mediated MASLD and cancer progression. A pathological increase in the expression of AKR1B1 was observed in experimental MASLD-HCC, and expression was positively correlated with high blood glucose levels. High-fructose diet+ diethylnitrosamine-treated animals also exhibited statistically significant elevation of metabolic markers and carcinogenesis markers. AKR1B1 inhibition with epalrestat or NARI-29 inhibited cellular metabolism in invitro and invivo models. Pathological AKR1B1 modulates hepatic metabolism to promote MASLD-associated hepatocarcinogenesis. Aldose reductase inhibition modulates the glycolytic pathway to prevent precancerous hepatocyte formation. This research work highlights AKR1B1 as a druggable target in metabolic dysfunction-associated steatotic liver disease (MASLD) and hepatocellular carcinoma (HCC), which could provide the basis for the development of new chemotherapeutic agents. Moreover, our results indicate the potential of plasma AKR1B1 levels as a prognostic marker and diagnostic test for MASLD and associated HCC. Additionally, a major observation in this study was that AKR1B1 is associated with the promotion of the Warburg effect in HCC.

Uncompetitive Inhibition of Polyol Pathway Enzymes by Daucus carota Linn. Extract and Management of Diabetes Mellitus

Background: The growing occurrence of complications associated with diabetes calls for the unending exploration of natural products for more efficient therapeutic substances. The polyol pathway is a foundational scheme involved in the development of diabetic complications. Retarding the activities of enzymes in the polyol pathway is, therefore, a potent method of managing these complications. Objective: This work assessed the ability of four non-leafy vegetables, namely Daucus carota Linn. (carrot), Abelmoschus esculentus (L.) Moench (okra), Allium cepa Linn. (onion), and Lycopersicon esculentum Mill. (tomato), to inhibit the activities of aldose reductase and sorbitol dehydrogenase. Method: The vegetables’ ability was evaluated by incubating the vegetables with suitable enzymes and substrates. Sample(s) with the lowest inhibitory concentration (IC50) was utilized to determine the mechanism of action of the enzymes by constructing the Lineweaver-Burk graph. Results: Results showed that the aqueous extract of carrot exhibited the lowest IC50 value for the inhibition of both aldose reductase (135.17 μg/mL) and sorbitol dehydrogenase (14.64 μg/mL), respectively. The double reciprocal plot also showed that the aqueous extract of carrot inhibited both aldose reductase and sorbitol dehydrogenase in an uncompetitive fashion. Conclusion: Aqueous extract of carrot successfully retarded the action of polyol pathway enzymes, which may result in the recovery of diabetic complications. This activity may due to the availability of phytochemicals, including carotenoids and phenylacetylenes.

Cemtirestat, an aldose reductase inhibitor and antioxidant compound, induces ocular defense against oxidative and inflammatory stress in rat models for glycotoxicity.

Fructose, endogenously produced as a consequence of activation of the polyol pathway under hyperglycemic conditions, contribute to formation of advanced glycoxidation end products (AGEs) and carbonyl stress. Oxidative stressis increased in diabetes (DM) due to AGEs formation and the utilization of NADPH by aldo-keto reductase, AKR1B1(AR), the first enzyme in polyol pathway. Since inhibition of AR is an attractive approach for the management of diabetic eye diseases, we aimed to compare the effects of a novel AR inhibitor (ARI)/antioxidant (AO) compound cemtirestat on eye tissues with the effects of ARI drug epalrestat and AOagent stobadine in rat model for glycotoxicity. One group of rats was fed high fructose (10% drinking water; 14 weeks), while type-2 DM was induced in the other group of rats with fructose plus streptozotocin (40 mg/kg-bw/day). Diabetic (D) and nondiabetic fructose-fed rats (F) were either untreated or treated with two different doses of cemtirestat (2.5 and 7.5 mg/kg-bw/day), epalrestat (25 and 50 mg/kg-bw/day),or stobadine (25 and 50 mg/kg-bw/day) for 14 weeks. Cemtirestat, epalrestat, and stobadine elaviate the increase in TNF-α, IL-1β, NF-ƙB, and caspase-3 in retina, lens, cornea, and sclera of F and D rats. Both glycotoxicity models resulted in a decrease in GSH to GSSG ratio and a change in glutathione S-transferase activity in eye tissues, but these alterations were improved especially with cemtirestat and stobadine. Lens D-sorbitol of D rats increased more than that of F rats, this increase was only attenuated by cemtirestat and epalrestat. Epalrestat was more effective than cemtirestat and stobadine in inhibiting the increase of vascular endothelial growth factor (VEGF)in the retina of F and D rats. Cemtirestat and stobadine but not epalrestat decreased high level of Nε-(carboxymethyl)lysine in the lens and retina of F and D rats. Cemtirestat is a potential therapeutic in protecting the rat eye against glycotoxicity insults.

AGE-RAGE axis culminates into multiple pathogenic processes: a central road to neurodegeneration.

Advanced glycation end-products (AGEs; e.g., glyoxal, methylglyoxal or carboxymethyl-lysine) are heterogenous group of toxic compounds synthesized in the body through both exogenous and endogenous pathways. AGEs are known to covalently modify proteins bringing about loss of functional alteration in the proteins. AGEs also interact with their receptor, receptor for AGE (RAGE) and such interactions influence different biological processes including oxidative stress and apoptosis. Previously, AGE-RAGE axis has long been considered to be the maligning factor for various human diseases including, diabetes, obesity, cardiovascular, aging, etc. Recent developments have revealed the involvement of AGE-RAGE axis in different pathological consequences associated with the onset of neurodegeneration including, disruption of blood brain barrier, neuroinflammation, remodeling of extracellular matrix, dysregulation of polyol pathway and antioxidant enzymes, etc. In the present article, we attempted to describe a new avenue that AGE-RAGE axis culminates to different pathological consequences in brain and therefore, is a central instigating component to several neurodegenerative diseases (NGDs). We also invoke that specific inhibitors of TIR domains of TLR or RAGE receptors are crucial molecules for the therapeutic intervention of NGDs. Clinical perspectives have also been appropriately discussed.

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In Vitro Inhibitory Activity and Molecular Docking Study of Selected Natural Phenolic Compounds as AR and SDH Inhibitors**

AbstractPolyol pathway enzymes, aldose reductase (EC 1.1.1.21; AR, ALR2), and sorbitol dehydrogenase (EC 1.1.1.14; SDH, SORD) have been widely investigated as the enzymes crucially involved in the pathogenesis of several chronic complications, including nephropathy, neuropathy, retinopathy, and cataracts associated with diabetes mellitus. Although phenolic compounds have been reported to possess many other biological activities, in continuation of our interest in designing and discovering potent inhibitors of AR and SDH, herein, we have evaluated these agents’ inhibitory potential against polyol pathway enzymes. Our in vitro studies revealed that all the derivatives show activity against recombinant human AR (rhAR) and SDH (rhSDH), with KI constants ranging from 9.37±0.16 μM to 77.22±2.49 μM and 2.51±0.10 μM to 42.16±1.03 μM, respectively. Among these agents, Prunetin and Phloridzin showed prominent inhibitory activity versus rhAR and rhSDH, while some were also determined to possess perfect dual activity. Moreover, in silico studies were also performed to rationalize binding site interactions of these agents with the target enzyme AR and SDH. According to ADME‐Tox was also determined that these derivatives be agents exhibiting suitable drug‐like properties. The compounds identified therapeutic potentials in this study may be promising for developing lead therapeutic agents to prevent polyol pathway complications.

Assessing the Phytochemical Profile and Potential of Traditional Herbal Infusions against Aldose Reductase through In Silico Studies and LC-MS/MS Analysis

In the current market, there is a growing interest in traditional herbal nutraceuticals. Therefore, herbal formulations have re-emerged as products with sought-after nutraceutical and disease-preventing properties. The health-promoting effects of herbal bioactives are attributed to the active phytoconstituents of these plants. Thus, the aim of the present study was to evaluate the putative nutraceutical effectiveness of the preparations of ten herbs (chamomile, purple coneflower, lemon verbena, pennyroyal, spearmint, oregano, marjoram, headed savory, sea buckthorn, and St. John’s wort) by combining in silico techniques and LC-MS/MS analysis. The binding potential of the selected phenolic compounds, according to literature and web databases, was investigated by using molecular target prediction tools. Aldose reductase (AR), an enzyme of polyol pathway which is related to hyperglycemic-induced pathologies, emerged as the most promising molecular target. The molecular docking results showed that rosmarinic acid, caftaric acid, naringenin, and quercetin presented the highest binding affinity. In a further step, the phytochemical profile of the examined infusions, obtained by LC-MS/MS analysis, revealed that the abovementioned compounds were present, mainly in the herbs of the Lamiaceae family, designating headed savory as the herbal infusion with possible significant inhibitory activity against AR.

W185 Phytocompounds from pedalium murex inhibits polyol pathway enzymes: Implication in prevention of microvascular diabetic complications through in-vitro, kinetics and molecular docking studies

W185 Phytocompounds from pedalium murex inhibits polyol pathway enzymes: Implication in prevention of microvascular diabetic complications through in-vitro, kinetics and molecular docking studies

In Search of Differential Inhibitors of Aldose Reductase

Aldose reductase, classified within the aldo-keto reductase family as AKR1B1, is an NADPH dependent enzyme that catalyzes the reduction of hydrophilic as well as hydrophobic aldehydes. AKR1B1 is the first enzyme of the so-called polyol pathway that allows the conversion of glucose into sorbitol, which in turn is oxidized to fructose by sorbitol dehydrogenase. The activation of the polyol pathway in hyperglycemic conditions is generally accepted as the event that is responsible for a series of long-term complications of diabetes such as retinopathy, cataract, nephropathy and neuropathy. The role of AKR1B1 in the onset of diabetic complications has made this enzyme the target for the development of molecules capable of inhibiting its activity. Virtually all synthesized compounds have so far failed as drugs for the treatment of diabetic complications. This failure may be partly due to the ability of AKR1B1 to reduce alkenals and alkanals, produced in oxidative stress conditions, thus acting as a detoxifying agent. In recent years we have proposed an alternative approach to the inhibition of AKR1B1, suggesting the possibility of a differential inhibition of the enzyme through molecules able to preferentially inhibit the reduction of either hydrophilic or hydrophobic substrates. The rationale and examples of this new generation of aldose reductase differential inhibitors (ARDIs) are presented.

Water-soluble fullerene derivatives: the inhibition effect on polyol pathway enzymes and antidiabetic potential on high-fat diet/low-dose streptozotocin-induced diabetes in rats

Water-soluble fullerene derivatives: the inhibition effect on polyol pathway enzymes and antidiabetic potential on high-fat diet/low-dose streptozotocin-induced diabetes in rats

Molecular docking and inhibition studies of vulpinic, carnosic and usnic acids on polyol pathway enzymes

Aldose reductase (AR) and sorbitol dehydrogenase (SDH) are important enzymes of the polyol pathway. In the current study, inhibitory effects of vulpinic acid (VA) carnosic acid (CA) and usnic acid (UA) on purified AR and SDH enzymes were determined. These enzymes inhibition could be essential to prevent diabetic complications. AR and SDH enzymes were purified from sheep kidney. Then, VA, CA and UA were tested in various concentrations against these enzymes activity in vitro. K I values were found to be as 1.46 ± 0.04, 5.13 ± 0.25 and 11.71 ± 0.27 μΜ for VA, CA and UA, respectively, for AR. K I constants were found to be as 15.32 ± 0.34, 145.60 ± 2.17 and 213.40 ± 2.64 μΜ VA, CA and UA, respectively, for SDH. These findings indicate that VA, CA and UA could be useful in the treatment of diabetic complications. Communicated by Ramaswamy H. Sarma

Laurus Nobilis Linn. Inhibits Polyol Pathway Enzymes: Strategy for Managing Diabetic Complications

Background: The rising incidence of diabetic complications necessitate the continuous search for safer, cheaper, and effective pharmacological agents. The polyol pathway is an underlying process implicated in the pathogenesis of diabetic complications. Inhibition of enzymes in the polyol pathway is a veritable means of ameliorating diabetic complications. Objective: This study evaluated the inhibitory potential of some spicy plants on the activities of polyol pathway enzymes (aldose reductase and sorbitol dehydrogenase). Methods: Aqueous extracts of Laurus nobilis (bay), Cinnamomum zeylanicum (cinnamon), Murraya koenigii (curry), Thymus vulgaris (thyme), and Curcuma longa (turmeric) were incubated with appropriate enzymes and substrates, and inhibition percentages were determined. Results: The results showed that bay extract had effective IC50 for the inhibition of both aldose reductase (174.87 μg/mL) and sorbitol dehydrogenase (37.08 μg/mL). It also revealed that bay extract inhibited aldose reductase and sorbitol dehydrogenase in a non-competitive and competitive manner, respectively. Conclusion: It is, therefore, concluded that bay extract effectively inhibited activities of polyol pathway enzymes and might contribute to the amelioration of diabetic complications.

Leafy vegetables inhibit activities of aldose reductase and sorbitol dehydrogenase in vitro

ABSTRACT One of the processes involved in pathogenesis of diabetic complications is the polyol pathway, which is catalyzed by the enzymes – aldose reductase and sorbitol dehydrogenase. Inhibition of one, or both, of these enzymes will shut down the polyol pathway ameliorating diabetic complications. Consumption of leafy vegetables is a dietary regime for management of diabetes mellitus and its complications. Inhibitory effects of leafy vegetables on activities of the polyol pathway enzymes aldose reductase and sorbitol dehydrogenase, and mode(s) of inhibition of these enzymes by the most effective plant were evaluated. Aqueous extract of leaves of African eggplant (Solanum macrocarpon L), bitter leaf (Vernonia amygdalina Del.), fluted pumpkin (Telfairia occidentalis Hook.) and clove basil leaf (Ocimum gratissimum L), were incubated with substrates (glucose and sorbitol) and enzymes, and their percent inhibition of enzymes determined spectrophotometrically. Due to low IC50 value, the aqueous extract of bitter leaf was used to assess kinetics of both enzymes. With exception of African eggplant, all plants displayed stronger inhibition of sorbitol dehydrogenase than aldose reductase. Vernonia amygdalina exhibited the lowest IC50 for aldose reductase (78.03 µg∙mL−1) and sorbitol dehydrogenase (22.17 µg∙mL−1). Vernonia amygdalina inhibited aldose reductase and sorbitol dehydrogenase in a noncompetitive, and mixed non-competitive manner, respectively. The V. amygdalina extract displayed potent inhibition of polyol pathway enzymes, and it needs to be determined if consumption affects the responses.

Carica papaya Linn. fruit extract inhibited the activities of aldose reductase and sorbitol dehydrogenase: possible mechanism for amelioration of diabetic complications

BackgroundDiabetes mellitus is a metabolic disorder which is associated with debilitating complications including eye disease, kidney disorder, and diabetic foot disease. One of the mechanisms implicated in the pathogenesis of diabetic complications is the polyol pathway. This study evaluated the inhibitory effect of aqueous extract of four tropical fruits, namely apple (Malus domestica Borkh.), banana (Musa paradisiaca Linn.), pawpaw (Carica papaya Linn.), and watermelon (Citrullus lanatus (Thunb.) Matsum & Nakai), on the activities of polyol pathway enzymes (aldose reductase and sorbitol dehydrogenase).ResultsAll the fruits, with the exception of banana, displayed stronger inhibition of sorbitol dehydrogenase than aldose reductase which culminated in low IC50 for the inhibition of sorbitol dehydrogenase. Of the fruit extracts tested, pawpaw inhibited both aldose reductase and sorbitol dehydrogenase most effectively with IC50 of 150.78 μg/mL and 46.30 μg/mL, respectively. Lineweaver-Burk plot also revealed that the pawpaw extract inhibited aldose reductase competitively while sorbitol dehydrogenase was inhibited in a mixed non-competitive manner.ConclusionAqueous extract of pawpaw fruit effectively inhibited polyol pathway enzymes, and this may be attributed to rich nutritional and phytochemical composition of the fruit. Consequently, the consumption of pawpaw fruit may contribute to the amelioration of diabetic complications.

(5-Hydroxy-4-oxo-2-styryl-4H-pyridin-1-yl)-acetic Acid Derivatives as Multifunctional Aldose Reductase Inhibitors.

As rate-limited enzyme of polyol pathway, aldose reductase (ALR2) is one of the key inhibitory targets for alleviating diabetic complications. To reduce the toxic side effects of the inhibitors and to decrease the level of oxidative stress, the inhibitory selectivity towards ALR2 against detoxicating aldehyde reductase (ALR1) and antioxidant activity are included in the design of multifunctional ALR2 inhibitors. Hydroxypyridinone derivatives were designed, synthesized and evaluated their inhibitory behavior and antioxidant activity. Notably, {2-[2-(3,4-dihydroxy-phenyl)-vinyl]-5-hydroxy-4-oxo-4H-pyridin-1-yl}-acetic acid (7l) was the most potent, with IC50 values of 0.789 μM. Moreover, 7l showed excellent selectivity towards ALR2 with selectivity index 25.23, which was much higher than that of eparlestat (17.37), the positive control. More significantly, 7l performed powerful antioxidative action. At a concentration of 1 μM, phenolic compounds 7l scavenged DPPH radical with an inhibitory rate of 41.48%, which was much higher than that of the well-known antioxidant Trolox, at 11.89%. Besides, 7l remarkably suppressed lipid peroxidation with a rate of 88.76% at a concentration of 100 μM. The binding mode derived from molecular docking proved that the derivatives were tightly bound to the activate site, suggesting strongly inhibitory action of derivatives against ALR2. Therefore, these results provided an achievement of multifunctional ALR2 inhibitors capable with potency for both selective ALR2 inhibition and as antioxidants.

Citrus aurantifolia (Christm.) Swingle (lime) Fruit Extract Inhibits the Activities of Polyol Pathway Enzymes

Diabetes mellitus is associated with several complications, which may result from one or more factors including increased flux of polyol pathway. This study evaluated the inhibitory potential of four citrus fruits namely Citrus paradisi Macfad. (grape), Citrus limon (L.) Osbeck (lemon), Citrus aurantifolia (Christm.) Swingle (lime) and Citrus sinensis (L.) Osbeck (orange), on the activities of aldose reductase and sorbitol dehydrogenase – the two enzymes that mediate the polyol pathway. This is determined by incubating citrus extracts with appropriate enzymes and substrates. Fruit extract with the lowest half maximal inhibitory concentration (IC50) was used to assess the mode of inhibition of the enzymes by preparing Lineweaver–Burk plot. Citrus fruits tested inhibited sorbitol dehydrogenase more than aldose reductase, which resulted in lowered IC50 values. Of all the citrus fruits tested, lime fruit extract displayed potent inhibition of aldose reductase (IC50: 138.66 μg/mL) and sorbitol dehydrogenase (IC50: 47.21 μg/mL). Kinetic studies also revealed that lime fruit extract inhibited the activities of both enzymes in a competitive manner. In conclusion, the inhibition of the polyol pathway enzymes by the lime fruit extract may be attributed to the presence of phytochemicals such as flavonoids and limonoids.

Retracted: P0991EFFECTS OF TRIGONELLA FOENUM GRAECUM AND SODIUM ORTHOVANADATE ON ALTERED RENAL MEMBRANE FUNCTIONS IN ALLOXAN DIABETIC RATS.

Abstract Background and Aims The present study was carried out to observe, the antihyperglycemic and renoprotective effect of sodium orthovanadate (SOV) and Trigonella foenum graecum seed powder (TSP) administration on blood glucose, renal functions, expression of glucose transporter, DNA fragmentation, inflammatory cytokines and oxidative stress markers in kidney tissues and to see whether the treatment with SOV and TSP was capable of reversing the diabetic effects. Method Diabetes was induced by administration of alloxan monohydrate (15 mg/100 g body weight.) and rats were treated with 2 IU insulin, 0.6mg/ml SOV, 5% TSP in the diet and a combination of 0.2 mg/ml SOV and 5% TSP separately for three weeks. Renal damage was assessed by measuring proteinuria, enzymuria, expression of glucose transporters, renin-angiotensin system, and activities of polyol pathway enzymes. Results Diabetic rats showed hyperglycemia with almost four fold high blood glucose levels. Activity of Na+K+ATPase decreased in diabetic kidney. Diabetic rats exhibited an increased level of lipid peroxidation, intracellular Ca2+ levels, and decreased membrane fluidity. Combined therapy of lower dose of SOV with TSP significantly reduced metabolites of polyol pathway, oxidative stress, nitric oxide, and N-acetyl-β-d-glucosaminidase activity with glucose transporter in kidney of alloxan diabetic rats. Markers of podocyte damage in kidney (nephrin, podocin, and podocalyxin) and their urinary excretion were normalized along with downregulation of the expression of kidney injury molecule-1 by SOV and TSP treatment. TSP treatment alone is partially effective in restoring the above diabetes induced alterations. Dietary combined SOV and TSP effectively countered the diabetes-induced structural abnormalities of renal tissue. Conclusion Our results showed that lower doses of SOV (0.2mg/ml) could be used in combination with TSP to effectively in normalization of altered metabolic parameters and membrane linked enzymes without any harmful side effect and renoprotective actions.