Aldose reductase inhibitors: therapeutic implications for diabetic complications

SORDD: mutation frequency and phenotype in predominantly axonal Charcot-Marie-Tooth disease of undefined genetic cause

Pathogenic, biallelic variants in SORD were identified in 2020 as a novel cause for autosomal-recessive Charcot-Marie-Tooth disease (CMT) type 2, an inherited neuropathy. SORD codes for the enzyme sorbitol dehydrogenase. Loss of this enzyme's activity leads to an increase of sorbitol in serum. We retrospectively screened 166 patients with axonal neuropathy (predominantly CMT type 2, but including intermediate form of CMT and distal hereditary motor neuropathy (dHMN)) without identified genetic etiology for SORD mutations at a single large German neuromuscular center. Clinical and electrophysiology exam findings were analyzed for genotype-phenotype correlation. Five patients of the total cohort of 166 patients harbored pathogenic variants in SORD (3%). The homozygous frameshift variant c.757delG (p.Ala253Glnfs*27) was the most common (4/5). One additional case carried this variant on one allele only and an additional pathogenic missense variant c.458C > A (p.Ala153Asp) on the other allele. Age of onset ranged from early infancy to mid-twenties, and phenotypes comprised axonal CMT (4) and dHMN (1). Our findings strengthen the importance of screening for pathogenic variants in SORD, especially in patients with genetically unconfirmed axonal neuropathy, especially CMT type 2 and dHMN.

Composition of the gut microbiome, role of diet, lifestyle, and antioxidant therapies in diabetes mellitus and diabetic retinopathy

The gut microbiome is a complex ecosystem in the gastrointestinal tract composed of trillions of bacteria, viruses, fungi, and protozoa. Disruption of this delicate ecosystem, formally called "dysbiosis", has been linked to a variety of metabolic and inflammatory pathologies. Several studies have focused on abnormal microbiome composition and correlated these findings with the development of type 2 diabetes mellitus (T2DM) and diabetic retinopathy (DR). However, given the complexity of this ecosystem, the current studies are narrow in design and present variable findings. Composition of the gut microbiome in patients with DR significantly differs from patients with diabetes without retinopathy as well as from healthy controls. Additionally, the gut microbiome has been shown to modify effects of medication, diet, exercise, and antioxidant use on the development and progression of DR. In this paper, we present a comprehensive review of literature on the effect of oxidative stress, antioxidant therapies, and dysbiosis on DR.

Parallelism and non-parallelism in diabetic nephropathy and diabetic retinopathy

Diabetic nephropathy (DN) and diabetic retinopathy (DR), as microvascular complications of diabetes mellitus, are currently the leading causes of end-stage renal disease (ESRD) and blindness, respectively, in the adult working population, and they are major public health problems with social and economic burdens. The parallelism between the two in the process of occurrence and development manifests in the high overlap of disease-causing risk factors and pathogenesis, high rates of comorbidity, mutually predictive effects, and partial concordance in the clinical use of medications. However, since the two organs, the eye and the kidney, have their unique internal environment and physiological processes, each with specific influencing molecules, and the target organs have non-parallelism due to different pathological changes and responses to various influencing factors, this article provides an overview of the parallelism and non-parallelism between DN and DR to further recognize the commonalities and differences between the two diseases and provide references for early diagnosis, clinical guidance on the use of medication, and the development of new drugs.

Novel acetic acid derivatives containing quinazolin-4(3H)-one ring: Synthesis, in vitro, and in silico evaluation of potent aldose reductase inhibitors

Aldose reductase (AR) is a crucial enzyme of the polyol pathway through which glucose is metabolized under conditions of hyperglycemia related to diabetes. A series of novel acetic acid derivatives containing quinazolin-4(3H)-one ring (1-22) was synthesized and tested for in vitro AR inhibitory effect. All the target compounds exhibited nanomolar activity against the target enzyme, and all compounds displayed higher activity as compared to the reference drug epalrestat. Among them, Compound 19, named 2-(4-[(2-[(4-methylpiperazin-1-yl)methyl]-4-oxoquinazolin-3(4H)-ylimino)methyl]phenoxy)acetic acid, displayed the strongest inhibitory effect with a KI value of 61.20 ± 10.18 nM. Additionally, these compounds were investigated for activity against L929, nontumoral fibroblast cells, and MCF-7, breast cancer cells using the MTT assay. Compounds 16 and 19 showed lower toxicity against the normal L929 cells. The synthesized compounds' (1-22) absorption, distribution, metabolism, and excretion properties were also evaluated. Molecular docking simulations were used to look into the possible binding mechanisms of these inhibitors against AR.

CADD Studies in the Discovery of Potential ARI (Aldose Reductase Inhibitors) Agents for the Treatment of Diabetic Complications

The lack of currently available drugs for treating diabetes complications has stimulated our interest in finding new Aldose Reductase inhibitors (ARIs) with more beneficial biological properties. One metabolic method uses aldose reductase inhibitors in the first step of the polyol pathway to control excess glucose flux in diabetic tissues. Computer-aided drug discovery (CADD) is key in finding and optimizing potential lead substances. AR inhibitors (ARI) have been widely discussed in the literature. For example, Epalrestat is currently the only ARI used to treat patients with diabetic neuropathy in Japan, India, and China. Inhibiting R in patients with severe to moderate diabetic autonomic neuropathy benefits heart rate variability. AT-001, an AR inhibitor, is now being tested in COVID-19 to see how safe and effective it reduces inflammation and cardiac damage. In summary, these results from animal and human studies strongly indicate that AR can cause cardiovascular complications in diabetes. The current multi-center, large-scale randomized human study of the newly developed powerful ARI may prove its role in diabetic cardiovascular disease to establish therapeutic potential. During the recent coronavirus disease (COVID-19) outbreak in 2019, diabetes and cardiovascular disease were risk factors for severely negative clinical outcomes in patients with COVID19. New data shows that diabetes and obesity are among the strongest predictors of COVID-19 hospitalization. Patients and risk factors for severe morbidity and mortality of COVID- 19.

Perilla frutescens: A Rich Source of Pharmacological Active Compounds

Perilla frutescens (L.) Britton, an important pharmaceutical and nutraceutical crop, is widely cultivated in East Asian countries. In this review, we present the latest research findings on the phytochemistry and pharmacological activities of P. frutescens. Different databases, including PubMed, Scopus, CNKI, Agricola, Scifinder, Embase, ScienceDirect, DOAJ, and Web of Science, were searched to present the best review. In this review, we clearly represent the active constituents responsible for each and every pharmacological activity, plausible mechanism of action, and maximum inhibitory concentrations, as well as IC₅₀ values. Approximately 400 different bioactive compounds, including alkaloids, terpenoids, quinines, phenylpropanoids, polyphenolic compounds, flavonoids, coumarins, anthocyanins, carotenoids, neolignans, fatty acids, polycosanols, tocopherols, and sitosterols, have been reported in the leaves, seeds, roots, and aerial parts of P. frutescens. The bioactive constituents of P. frutescens exhibited different enzyme-inhibition properties, including antihyaluronidase effects and aldose reductase inhibitory, α-glucosidase inhibitory, xanthine oxidase inhibitory, and tyrosinase inhibitory properties. P. frutescens showed strong anti-inflammatory, antidepressant, anti-spasmodic, anticancer, antioxidant, antimicrobial, insecticidal, neuroprotective, and hepatoprotective effects. Hence, the active constituents of P. frutescens used in the treatment of diabetes and diabetic complications (retinopathy, neuropathy, and nephropathy), prevention of hyperuricemia in gout patients, hyper pigmentation, allergic conditions, skin inflammation, skin allergy, atopic dermatitis, periodontosis, androgenic alopecia, gastric inflammation, oesophagitis, carcinogenesis, cardiovascular, Alzheimer’s, Parkinson’s, and cerebral ischemic disorders. Furthermore, we revealed the most active constituents and possible mechanisms of the pharmacological properties of P. frutescens.

Type 2 Diabetes Contributes to Altered Adaptive Immune Responses and Vascular Inflammation in Patients With SARS-CoV-2 Infection

SARS-CoV-2, which initially emerged in November of 2019, wreaked havoc across the globe by leading to clinical acute respiratory distress syndrome and continues to evade current therapies today due to mutating strains. Diabetes mellitus is considered an important risk factor for progression to severe COVID disease and death, therefore additional research is warranted in this group. Individuals with diabetes at baseline have an underlying inflammatory state with elevated levels of pro-inflammatory cytokines and lower levels of anti-inflammatory cytokines, both of which cause these individuals to have higher susceptibility to SARS- CoV2 infection. The detrimental effects of SARS-CoV-2 has been attributed to its ability to induce a vast cell mediated immune response leading to a surge in the levels of pro-inflammatory cytokines. This paper will be exploring the underlying mechanisms and pathophysiology in individuals with diabetes and insulin resistance making them more prone to have worse outcomes after SARS- CoV2 infection, and to propose an adjunctive therapy to help combat the cytokine surge seen in COVID-19. It will also look at the immunomodulatory effects of glutathione, an antioxidant shown to reduce immune dysregulation in other diseases; Vitamin D, which has been shown to prevent COVID-19 patients from requiring more intensive care time possibly due to its ability to decrease the expression of certain pro-inflammatory cytokines; and steroids, which have been used as immune modulators despite their ability to exacerbate hyperglycemia.

Utilization of Gelling Polymer to Formulate Nanoparticles Loaded with Epalrestat-Cyclodextrin Inclusion Complex: Formulation, Characterization, In-Silico Modelling and In-Vivo Toxicity Evaluation

Epalrestat (EPL) is an aldose reductase inhibitor with poor aqueous solubility that affects its therapeutic efficacy. The research study was designed to prepare epalrestat-cyclodextrins (EPL-CDs) inclusion complexes to enhance the aqueous solubility by using beta-cyclodextrin (β-CD) and sulfobutyl ether₇ β-CD (SBE₇ β-CD). Furthermore, polymeric nanoparticles (PNPs) of EPL-CDs were developed using chitosan (CS) and sodium tripolyphosphate (sTPP). The EPL-CDs complexed formulations were then loaded into chitosan nanoparticles (CS NPs) and further characterized for different physico-chemical properties, thermal stability, drug-excipient compatibility and acute oral toxicity studies. In-silico molecular docking of cross-linker with SBE₇ β-CD was also carried out to determine the binding site of the CDs with the cross-linker. The sizes of the prepared NPs were laid in the range of 241.5–348.4 nm, with polydispersity index (PDI) ranging from 0.302–0.578. The surface morphology of the NPs was found to be non-porous, smooth, and spherical. The cumulative percentage of drug release from EPL-CDs loaded CS NPs was found to be higher (75–88%) than that of the pure drug (25%). Acute oral toxicity on animal models showed a biochemical, histological profile with no harmful impact at the cellular level. It is concluded that epalrestat-cyclodextrin chitosan nanoparticles (EPL-CDs-CS NPs) with improved solubility are safe for oral administration since no toxicity was reported on vital organs in rabbits.

Natural Compounds as Source of Aldose Reductase (AR) Inhibitors for the Treatment of Diabetic Complications: A Mini Review

BACKGROUND

Aldol reductase (AR) is the polyol pathway's main enzyme that portrays a crucial part in developing 'complications of diabetes' involving cataract, retinopathy, nephropathy, and neuropathy. These diabetic abnormalities are triggered tremendously via aggregation of sorbitol formation (catalyzed by AR) in the polyol pathway. Consequently, it represents an admirable therapeutic target and vast research was done for the discovery of novel molecules as potential AR inhibitors for diabetic complications.

OBJECTIVE

This review article has been planned to discuss an outline of diabetic complications, AR and its role in diabetic complications, natural compounds reported as AR inhibitors, and benefits of natural/plant derived AR inhibitors for the management of diabetic abnormalities.

RESULTS

The goal of AR inhibition remedy is to stabilize the increased flux of blood glucose and sorbitol via the 'polyol pathway' in the affected tissues. A variety of synthetic inhibitors of AR have been established such as tolrestat and sorbinil, but both of these face limitations including low permeability and health problems. Pharmaceutical industries and other scientists were also undertaking work to develop newer, active, and 'safe' AR inhibitors from natural sources. Therefore, several naturally found molecules were documented to possess a potent inhibitory action on AR activity.

CONCLUSION

Natural inhibitors of AR appeared as harmless pharmacological agents for controlling diabetic complications. The detailed literature throughout this article shows the significance of herbal extracts and phytochemicals as prospective useful AR inhibitors in treating diabetic complications.

Determination of Afzelin and Astragalin from Lespedeza cuneata on Aldose Reductase Inhibition

The bioactive chemicals in L. cuneata were investigated by repeated column chromatography and their effect on aldose reductase (AR), obtained from rat lenses, was examined. Results showed that the ethyl acetate and n-butanol fractions of L. cuneata exhibited potential inhibitory effect against AR with IC50 values of 0.57 and 0.49 μg/mL, respectively. Phytochemical analysis of these two fractions resulted in the isolation of five flavonoids namely, acacetin (1), afzelin (2), astragalin (3), kaempferol (4) and scutellarein 7-O-glucoside (5). The AR inhibitory effect of compounds 1-5 was explored; compounds 2, 3 and 5 showed potential AR-inhibitory effects with IC50 values of 2.20, 1.91 and 12.87 μM, respectively. Quantitative analysis of afzelin (2) and astragalin (3) in L. cuneata by high performance liquid chromatography with ultraviolet detection revealed its content to be 0.722-11.828 and 2.054-7.006 mg/g, respectively. Overall, this study showed that L. cuneata is rich in flavonoids with promising AR-inhibitory activities, which can be utilized for the development of natural therapies for treating and managing diabetic complications.

Aldose Reductase: An Emerging Target for Development of Interventions for Diabetic Cardiovascular Complications

Diabetes is a leading cause of cardiovascular morbidity and mortality. Despite numerous treatments for cardiovascular disease (CVD), for patients with diabetes, these therapies provide less benefit for protection from CVD. These considerations spur the concept that diabetes-specific, disease-modifying therapies are essential to identify especially as the diabetes epidemic continues to expand. In this context, high levels of blood glucose stimulate the flux via aldose reductase (AR) pathway leading to metabolic and signaling changes in cells of the cardiovascular system. In animal models flux via AR in hearts is increased by diabetes and ischemia and its inhibition protects diabetic and non-diabetic hearts from ischemia-reperfusion injury. In mouse models of diabetic atherosclerosis, human AR expression accelerates progression and impairs regression of atherosclerotic plaques. Genetic studies have revealed that single nucleotide polymorphisms (SNPs) of the ALD2 (human AR gene) is associated with diabetic complications, including cardiorenal complications. This Review presents current knowledge regarding the roles for AR in the causes and consequences of diabetic cardiovascular disease and the status of AR inhibitors in clinical trials. Studies from both human subjects and animal models are presented to highlight the breadth of evidence linking AR to the cardiovascular consequences of diabetes.

Phytosynthesis of Silver Nanoparticles Using Perilla frutescens Leaf Extract: Characterization and Evaluation of Antibacterial, Antioxidant, and Anticancer Activities

Purpose

The present study investigates the phytosynthesis of silver nanoparticles (AgNPs) using Perilla frutescens leaf extract, which acts as a reducing agent for the conversion of silver ions (Ag+) into AgNPs. P. frutescens leaf synthesized AgNPs (PF@AgNPs) were evaluated for biomedical properties including antibacterial, antioxidant and anticancer activities.

Materials and Methods

PF@AgNPs were synthesized using P. frutescens leaf extract and silver nitrate solution. The morphology and physical properties of PF@AgNPs were studied by spectroscopic techniques including, UV-Vis, FTIR, TEM, XRD, DLS, and TGA. Antibacterial activity of PF@AgNPs was evaluated by disk diffusion assay. Antioxidant activity of PF@AgNPs was checked by 2.2-diphenyl-1-picrylhydrazyl (DPPH), and 2.2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging assays. Anticancer activity of PF@AgNPs was checked by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Cytotoxic effects of PF@AgNPs on most susceptible cancer cell lines were observed by phase contrast microscopy.

Results

PF@AgNPs showed surface plasmon resonance peak at 461 nm. XRD pattern showed that the PF@AgNPs were face-centered cubic crystals with a mean size of 25.71 nm. TEM analysis revealed the different shapes (spherical, rhombic, triangle, and rod) of PF@AgNPs. Zeta potential value (-25.83 mV) indicated that PF@AgNPs were long-term stable and not agglomerated. A low polydispersity index value (0.389) indicated the monodispersity of PF@AgNPs. TGA revealed the high thermal stability of PF@AgNPs. PF@AgNPs exhibited maximum inhibition against Escherichia coli, followed by Bacillus subtilis and Staphylococcus aureus. PF@AgNPs showed maximum inhibition of 68.02 and 62.93% against DPPH and ABTS-free radicals, respectively. PF@AgNPs showed significant anticancer activity against human colon cancer (COLO205) and prostate adenocarcinoma (LNCaP). PF@AgNPs exhibited apoptotic effects on LNCaP cells including cell shrinkage, membrane blebbing, chromatin condensation, fragmentation of nuclei, and formation of apoptotic bodies.

Conclusion

The present study reports the successful synthesis of PF@AgNPs using P. frutescens leaf extract. The synthesized PF@AgNPs are FCC crystals, monodispersed, long-term stable, and non-agglomerated. The observed antibacterial, antioxidant, and anticancer activities demonstrate the potential biomedical applications of PF@AgNPs.

An Insight into the Synthesis and SAR of 2,4-Thiazolidinediones (2,4-TZD) as Multifunctional Scaffold: A Review

2,4-Thiazolidinedione (2,4-TZD) is a versatile pharmacophore, a privileged scaffold, and a remarkable sulphur-containing heterocyclic compound with diverse pharmacological activities. The multifarious biological activities, due to different mechanisms of action, low cost, and easy availability of 2,4-TZD impressed medicinal chemists to integrate this moiety to develop various lead compounds with diverse therapeutic actions. This resulted in the swift development in the last decade for generating different new potential molecules bearing 2,4-TZD. In this review, the authors attempt to shape and present the latest investigations (2012 onwards) going on in generating promising 2,4-TZD containing lead compounds. The data has been collected and analyzed to develop the structure-activity relationship (SAR). The SAR and active pharmacophores of various leads accountable for antidiabetic, anticancer, antimicrobial, and antioxidant activities have also been illustrated. This review also highlighted some of the important chemical synthetic routes for the preparation of various 2,4-TZD derivatives. This review will definitely serve as a useful source of structural information to medicinal chemists and may be utilized for the strategic design of potent 2,4-TZD derivatives in the future.

Therapeutic application of nutraceuticals in diabetic nephropathy: Current evidence and future implications

Diabetes mellitus (DM) is a common metabolic disease which may cause several complications, such as diabetic nephropathy (DN). The routine medical treatments used for DM are not effective enough and have many undesirable side effects. Moreover, the global increased prevalence of DM makes researchers try to explore potential complementary or alternative treatments. Nutraceuticals, as natural products with pharmaceutical agents, have a wide range of therapeutic properties in various pathologic conditions such as DN. However, the exact underlying mechanisms have not been fully understood. The purpose of this review is to summarize recent findings on the effect of nutraceuticals on DN.

Dihydrobenzoxazinone derivatives as aldose reductase inhibitors with antioxidant activity

Dihydrobenzoxazinone based design and synthesis produced two series of compounds as aldose reductase (ALR2) inhibitor candidates. In particular, phenolic residues were embodied into the compounds for the combination of strengthening the inhibitory acitvity and antioxidant ability to retard the progression of diabetic complications. Most of the derivatives with styryl side chains exhibited excellent activities on selective ALR2 inhibition with IC₅₀ values ranging from 0.082 to 0.308 μM, and {8-[2-(4-hydroxy-phenyl)-vinyl]-2-oxo-2,3-dihydro-benzo[1,4]oxazin-4-yl}-acetic acid (3a) was the most potent. More significantly, most of dihydrobenzoxazinone compounds revealed not only good inhibitory effect on ALR2, but also showed powerful antioxidant activity. Notably, phenolic compound 3a was even comparable to the well-known antioxidant Trolox, confirming that the C8 p-hydroxystyryl substitution was key structure of lowering oxidative stress. Therefore, these results provided an achievement of multifunctional ALR2 inhibitors possessing capacities for both ALR2 inhibition and as antioxidants.

Current molecular aspects in the development and treatment of diabetes

Diabetes mellitus (DM) leads to microvascular, macrovascular, and neurological complications. Less is understood about the mechanisms of this disease that give rise to weak bones. The many molecular mechanisms proposed to explain the damage caused by chronic hyperglycemia are organ and tissue dependent. Since all the different treatments for DM involve therapeutic activity combined with side effects and each patient represents a unique condition, there is no generalized therapy. The alterations stemming from hyperglycemia affect metabolism, osmotic pressure, oxidative stress, and inflammation. In part, hemodynamic modifications are linked to the osmotic potential of the excess of carbohydrates implicated in the disease. The change in osmotic balance increases as the disease progresses because hyperglycemia becomes chronic. The aim of the current contribution is to provide an updated overview of the molecular mechanisms that participate in the development and treatment of diabetes.

Identification of quinoxalin-2(1H)-one derivatives as a novel class of multifunctional aldose reductase inhibitors

Aim: Targeting aldose reductase and oxidative stress with quinoxalin-2(1 H)-one derivatives having a 1-hydroxypyrazole head as the bioisosteric replacement of carboxylic acid. Methodology & results: Aldose reductase inhibition, selectivity and antioxidant potency of all the synthesized compounds were evaluated, and binding modes were studied by molecular docking. Most of the derivatives showed potent and selective aldose reductase inhibition, and among them 13d was the most active (IC50 = 0.107 μM), suggesting success of the bioisosteric strategy. Phenolic 3,4-dihydroxyl compound 13f showed strong antioxidant ability even comparable to that of the well-known antioxidant Trolox. Conclusion: The present study identified the excellent bioisostere of the 1-hydroxypyrazole head group along with phenolic hydroxyl and vinyl spacer in C3 side chain on constructing quinoxalinone-based multifunctional aldose reductase inhibitors.

Vitamin K1 prevents diabetic cataract by inhibiting lens aldose reductase 2 (ALR2) activity

This study investigated the potential of vitamin K1 as a novel lens aldose reductase inhibitor in a streptozotocin-induced diabetic cataract model. A single, intraperitoneal injection of streptozotocin (STZ) (35 mg/kg) resulted in hyperglycemia, activation of lens aldose reductase 2 (ALR2) and accumulation of sorbitol in eye lens which could have contributed to diabetic cataract formation. However, when diabetic rats were treated with vitamin K1 (5 mg/kg, sc, twice a week) it resulted in lowering of blood glucose and inhibition of lens aldose reductase activity because of which there was a corresponding decrease in lens sorbitol accumulation. These results suggest that vitamin K1 is a potent inhibitor of lens aldose reductase enzyme and we made an attempt to understand the nature of this inhibition using crude lens homogenate as well as recombinant human aldose reductase enzyme. Our results from protein docking and spectrofluorimetric analyses clearly show that vitamin K1 is a potent inhibitor of ALR2 and this inhibition is primarily mediated by the blockage of DL-glyceraldehyde binding to ALR2. At the same time docking also suggests that vitamin K1 overlaps at the NADPH binding site of ALR2, which probably shows that vitamin K1 could possibly bind both these sites in the enzyme. Another deduction that we can derive from the experiments performed with pure protein is that ALR2 has three levels of affinity, first for NADPH, second for vitamin K1 and third for the substrate DL-glyceraldehyde. This was evident based on the dose-dependency experiments performed with both NADPH and DL-glyceraldehyde. Overall, our study shows the potential of vitamin K1 as an ALR2 inhibitor which primarily blocks enzyme activity by inhibiting substrate interaction of the enzyme. Further structural studies are needed to fully comprehend the exact nature of binding and inhibition of ALR2 by vitamin K1 that could open up possibilities of its therapeutic application.

Coumarin tethered cyclic imides as efficacious glucose uptake agents and investigation of hit candidate to probe its binding mechanism with human serum albumin

A series of novel coumarin-cyclic imide conjugates (1a-1j) were designed and synthesized to evaluate their glucose uptake activity by insulin resistant liver hepatocyte carcinoma (HepG2) cells through 2-NBDG uptake assay. Compounds (1a-1j) were characterised using various analytical methods such as ¹H NMR, ¹³C NMR, IR, GC-MS, elemental and single-crystal X-ray diffraction techniques. Compounds (1a-1j) exhibited 85.21 - 65.80% of glucose uptake and showed low level of cytotoxicity towards human embryonic kidney cells (HEK-293) indicating good selectivity and safety profile. Compound 1f was identified as a hit candidate exhibiting 85.21% of glucose uptake which was comparable with standard antidiabetic drug Metformin (93.25% glucose uptake). Solution stability study under physiological pH conditions ≈ (3.4 - 8.7), indicates that compound 1f is sufficiently stable at varied pH conditions and thereby compatible with bio-physiological environments. Interaction of 1f with human serum albumin (HSA) were also studied which quantifies that compound 1f binds with HSA efficiently through facile binding reaction in solution. Fluorescence, UV-vis spectrophotometry and molecular modeling methodologies were employed for studying the interaction mechanism of compound 1f with protein.

Polyphenols of marine red macroalga Symphyocladia latiuscula ameliorate diabetic peripheral neuropathy in experimental animals

Aims

Chronic hyperglycaemia activates the polyol pathway of glucose metabolism thereby stimulating the activation aldose reductase enzyme that in turn initiates a cascade of deleterious events, eventually, leading to nerve damage or neuropathy. Marine macroalgae and their isolated chemical constituents have been found to possess potential antidiabetic activity and have proved beneficial in the treatment of diabetes. In this study the neuroprotective effect of polyphenols isolated from the red macroalga Symphyocladia latiuscula was evaluated in experimental diabetic peripheral neuropathy.

Main methods

The polyphenolic fraction from Symphyocladia latiuscula was isolated. Diabetic peripheral neuropathy (DPN) was induced in animals by intraperitoneal injection of streptozotocin (45 mg/kg, b. w) and maintained for 6 weeks followed by treatment with SLPP or epalrestat. Nerve Conduction Velocity (NCV) and Compound Muscle Action Potential (CMAP) were measured using a non-invasive method followed by muscular grip strength test. Sciatic nerve aldose reductase activity, sorbitol accumulation, Na⁺K⁺-ATPase activity, production of pro-inflammatory cytokines and expression of AR and PKC were assessed.

Key findings

The Symphyocladia latiuscula polyphenols (SLPP) were found to inhibit aldose reductase activity as well as their expression in diabetic animals thereby improving the NCV, CMAP and muscle grip strength. Improvements in the sciatic nerve Na⁺K⁺-ATPase activity and intraneural accumulation of sorbitol, an index of aldose reductase overactivity, were evident with SLPP treatment. The production of pro-inflammatory cytokines (IL-6, IL-1β and TNF-α) and expression of protein kinase C (PKC) were also diminished.

Significance

The data suggest that the polyphenols of Symphyocladia latiuscula have neuroprotective potential against experimental DPN.

Understanding Aldose Reductase-Inhibitors interactions with free energy simulation

Aldose Reductase (AR) reduces a variety of substrates, such as aldehydes, aldoses and corticosteroids. It is the first and rate-limiting enzyme of the polyol pathway and is an important target enzyme for diabetes-associated complications, including retinopathy, neuropathy, and nephropathy. Inhibitors targeting this enzyme are structurally different and some of them have side effects. In existing publications, computational techniques are applied to investigate the binding affinities of existing inhibitors and predicting the affinities of newly designed ligands. However, these calculations only employ coarse and approximated methods such as docking and MM/PBSA. Brute force simulations are employed to study the dynamics of the system but no converged statistics is obtained. As a result, these computations provide results not consistent with experimental values and large discrepancies exist. In the current work, we employ the enhanced sampling technique of alchemical free energy simulation to calculate the binding affinities of several ligands targeting AR. The statistical error is defined with care and the correlation in the time-series data is fully considered. The statistically optimal estimators are used to extract the free energy estimates and the predicted results are in agreement with the experimental values. Less computationally demanding end-point free energy methods are also performed to compare their efficiency with the alchemical methods. As is expected, the end-point methods are of less accuracy and reliability compared with the alchemical free energy methods. The decomposition of the free energy difference in each alchemical transformation into the enthalpic and entropic components gives further insights on the thermodynamics. The enthalpy-entropy compensation is observed in this case. As the structural data obtained from experiments are only snapshots and more details are needed to understand the dynamics of the protein-ligand system, the conformational ensemble is analyzed. We identify important residues involved in the protein-ligand binding case and short-lived interactions formed due to fluctuations in the conformational ensemble. The current work shed light on the atomic detailed understanding of the dynamics of AR-inhibitors interactions.

Aldose reductase inhibitors: 2013-present

INTRODUCTION

Aldose reductase (ALR2) is both the key enzyme of the polyol pathway, whose activation under hyperglycemic conditions leads to the development of chronic diabetic complications, and the crucial promoter of inflammatory and cytotoxic conditions, even under a normoglycemic status. Accordingly, it represents an excellent drug target and a huge effort is being done to disclose novel compounds able to inhibit it.

AREAS COVERED

This literature survey summarizes patents and patent applications published over the last 5 years and filed for natural, semi-synthetic and synthetic ALR2 inhibitors. Compounds described have been discussed and analyzed from both chemical and functional angles.

EXPERT OPINION

Several ALR2 inhibitors with a promising pre-clinical ability to address diabetic complications and inflammatory diseases are being developed during the observed timeframe. Natural compounds and plant extracts are the prevalent ones, thus confirming the use of phytopharmaceuticals as an increasingly pursued therapeutic trend also in the ALR2 inhibitors field. Intriguing hints may be taken from synthetic derivatives, the most significant ones being represented by the differential inhibitors ARDIs. Differently from classical ARIs, these compounds should fire up the therapeutic efficacy of the class while minimizing its side effects, thus overcoming the existing limits of this kind of inhibitors.

Human Aldose Reductase Expression Prevents Atherosclerosis Regression in Diabetic Mice

Guidelines to reduce cardiovascular risk in diabetes include aggressive LDL lowering, but benefits are attenuated compared with those in patients without diabetes. Consistent with this, we have reported in mice that hyperglycemia impaired atherosclerosis regression. Aldose reductase (AR) is thought to contribute to clinical complications of diabetes by directing glucose into pathways producing inflammatory metabolites. Mice have low levels of AR, thus raising them to human levels would be a more clinically relevant model to study changes in diabetes under atherosclerosis regression conditions. Donor aortae from Western diet-fed Ldlr^-/- mice were transplanted into normolipidemic wild-type, Ins2Akita (Akita^+/- , insulin deficient), human AR (hAR) transgenic, or Akita^+/- /hAR mice. Akita^+/- mice had impaired plaque regression as measured by changes in plaque size and the contents of CD68⁺ cells (macrophages), lipids, and collagen. Supporting synergy between hyperglycemia and hAR were the even more pronounced changes in these parameters in Akita^+/- /hAR mice, which had atherosclerosis progression in spite of normolipidemia. Plaque CD68⁺ cells from the Akita^+/- /hAR mice had increased oxidant stress and expression of inflammation-associated genes but decreased expression of anti-inflammatory genes. In summary, hAR expression amplifies impaired atherosclerosis regression in diabetic mice, likely by interfering with the expected reduction in plaque macrophage inflammation.

Novel quinazolinone-based 2,4-thiazolidinedione-3-acetic acid derivatives as potent aldose reductase inhibitors

Aim: Targeting aldose reductase enzyme with 2,4-thiazolidinedione-3-acetic acid derivatives having a bulky hydrophobic 3-arylquinazolinone residue. Materials & methods: All the target compounds were structurally characterized by different spectroscopic methods and microanalysis, their aldose reductase inhibitory activities were evaluated, and binding modes were studied by molecular modeling. Results: All the synthesized compounds proved to inhibit the target enzyme potently, exhibiting IC50 values in the nanomolar/low nanomolar range. Compound 5i (IC50 = 2.56 nM), the most active of the whole series, turned out to be almost 70-fold more active than the only marketed aldose reductase inhibitor epalrestat. Conclusion: This work represents a promising matrix for developing new potential therapeutic candidates for prevention of diabetic complications through targeting aldose reductase enzyme.

[Formula: see text]

Antidiabetic plant-derived nutraceuticals: a critical review

Diabetes mellitus (DM) is one of the major health problems in the world, especially amongst the urban population. Chemically synthesized drugs used to decrease the ill effects of DM and its secondary complications cause adverse side effects, viz., weight gain, gastrointestinal disturbances, and heart failure. Currently, various other approaches, viz., diet control, physical exercise and use of antidiabetic plant-derived molecules/foods are advocated to manage DM, as they are economical with fewer or no side effects. This review mainly focuses on antidiabetic plants, chemically characterized plant molecules and plant-based foods in the treatment of DM. Very little science-based evidence is available on the mechanism of action of plant-derived food molecules on the DM targets. Critical DM targets include α-amylase, α-glucosidase, DPP-IV, aldose reductase, PPAR-γ, AMP kinase and GLUT4. In-depth studies carried out on a few of those targets with specific mechanisms of action are addressed in this review. This review may help future researchers in identifying a right plant molecule to treat DM or to develop food formulations for DM management.

Enhanced dissolution and skin permeation profiles of epalrestat with β-cyclodextrin derivatives using a cogrinding method

Epalrestat (EPL) is a water-insoluble drug (14μM) that inhibits aldose reductase. This study investigated the interactions between β-cyclodextrin (CD) derivatives and EPL to determine the solubilizing effect on EPL from phase solubility diagrams. We improved the solubility of EPL in water by adding β-CD derivatives. Moreover, the solubility of EPL mixed with β-CD derivatives by cogrinding in a ball mill method was about 2-3 times higher than those of EPL with the same CD concentration (5mM) calculated from phase solubility diagrams. In addition, we investigated the effect of β-CD derivatives on in vitro percutaneous absorption of EPL through hairless mouse skin. Among the coground mixtures of EPL and β-CD derivatives, the mixture containing methyl (ME)-β-CD showed the strongest enhancement of EPL skin permeation. Furthermore, adding 10wt% urea as a skin permeation enhancer after cogrinding with ME-β-CD improved the flux of EPL 300 times compared to the flux of EPL alone. This result indicates the ME-β-CD ground mixture system with urea has potential as a new transdermal drug delivery system of EPL for diabetic neuropathy.

Structure based comprehensive modelling, spatial fingerprints mapping and ADME screening of curcumin analogues as novel ALR2 inhibitors

Aldose reductase (ALR2) inhibition is the most legitimate approach for the management of diabetic complications. The limited triumph in the drug development against ALR2 is mainly because of its close structural similarity with the other members of aldo-keto reductase (AKR) superfamily viz. ALR1, AKR1B10; and lipophilicity problem i.e. poor diffusion of synthetic aldose reductase inhibitors (ARIs) to target tissues. The literature evidenced that naturally occurring curcumin demonstrates relatively specific and non-competitive inhibition towards human recombinant ALR2 over ALR1 and AKR1B10; however β-diketone moiety of curcumin is a specific substrate for liver AKRs and accountable for it’s rapid in vivo metabolism. In the present study, structure based comprehensive modelling studies were used to map the pharmacophoric features/spatial fingerprints of curcumin analogues responsible for their ALR2 specificity along with potency on a data set of synthetic curcumin analogues and naturally occurring curcuminoids. The data set molecules were also screened for drug-likeness or ADME parameters, and the screening data strongly support that curcumin analogues could be proposed as a good drug candidate for the development of ALR2 inhibitors with improved pharmacokinetic profile compared to curcuminoids due to the absence of β-diketone moiety in their structural framework.

In vitro and in vivo inhibition of aldose reductase and advanced glycation end products by phloretin, epigallocatechin 3-gallate and [6]-gingerol

Hyperglycemic stress activates polyol pathway and aldose reductase (AR) key enzyme responsible for generating secondary complications during diabetes. In this study the therapeutic potential of phloretin, epigallocatechin 3-gallate (EGCG) and [6]-gingerol were evaluated for anti-glycating and AR inhibitory activity in vitro and in vivo systems. Human retinal pigment epithelial (HRPE) cells were induced with high glucose supplemented with the phloretin, EGCG and [6]-gingerol. Aldose reductase activity, total advanced glycation end products (AGEs) and enzyme inhibitor kinetics were assessed. Male C57BL/6J mice were randomly assigned to one of the different treatments (bioactive compounds at 2 concentrations each) with either a low fat diet or high fat diet (HFD). After sixteen weeks, AGE accumulation and AR activity was determined in heart, eyes and kidney. High glucose induced toxicity decreased cell viability compared to the untreated cells and AR activity increased to 2-5 folds from 24 to 96h. Pre-treatment of cells with phloretin, EGCG and [6]-gingerol improved cell viability and inhibited AR activity. The enzyme inhibition kinetics followed a non-competitive mode of inhibition for phloretin and EGCG whereas [6]-gingerol indicated uncompetitive type of inhibition against AR. Data from the animal studies showed high plasma glucose levels in HFD group over time, compared to the low fat diet. HFD group developed cataract and AR activity increased to 4 folds compared to the group with low fat diet. Administration of EGCG, phloretin and [6]-gingerol significantly reduced blood sugar levels, AGEs accumulation, and AR activity. These findings could provide a basis to consider using the selected dietary components alone or in combination with other therapeutic approaches to prevent diabetes-related complications in humans.

Investigation of synergistic mechanism and identification of interaction site of aldose reductase with the combination of gigantol and syringic acid for prevention of diabetic cataract

BACKGROUND

Gigantol and syringic acid (SA) have been shown to synergistically prevent formation of diabetic cataract (DC). However, the exact mechanism of this effect is unknown. Here, we investigate the effect of these compounds on the activity of aldose reductase (AR) and cataract formation.

METHODS

We examined the synergistic anti-cataract efficacy of gigantol and SA in the high glucose- and streptozotocin -induced DC rat model; synergism was evaluated using Jin's formula. We investigated possible mechanisms of action by measuring AR expression and activity and levels of sorbitol using enzyme kinetics, Western blot, and RT-PCR. Finally, we examined binding interaction between AR and both compounds using a combination of site-directed mutagenesis, recombinant expression of wild-type and mutant proteins, and enzyme kinetics.

RESULTS

Combination treatment of gigantol and SA synergistically protected both HLECs(human lens epithelial cells) grown in vitro and DC formation in STZ-induced rats in vivo. Synergism was attributed to inhibition of AR activity, downregulation of AR expression via impaired transcription, and decreased sorbitol levels. Enzyme kinetics studies showed that the activity of an AR Asn160Ala mutant protein was significantly decreased compared to wild-type AR, confirming that Asn160 is a key residue for interaction between AR and both compounds.

CONCLUSION

Combined administration of gigantol and SA synergize to enhance anti-cataract efficacy. The synergistic effect is mainly attributed to disruption of the polyol pathway and inhibition of AR activity.

Diabetic complications within the context of aging: Nicotinamide adenine dinucleotide redox, insulin C-peptide, sirtuin 1-liver kinase B1-adenosine monophosphate-activated protein kinase positive feedback and forkhead box O3

Recent research in nutritional control of aging suggests that cytosolic increases in the reduced form of nicotinamide adenine dinucleotide and decreasing nicotinamide adenine dinucleotide metabolism plays a central role in controlling the longevity gene products sirtuin 1 (SIRT1), adenosine monophosphate‐activated protein kinase (AMPK) and forkhead box O3 (FOXO3). High nutrition conditions, such as the diabetic milieu, increase the ratio of reduced to oxidized forms of cytosolic nicotinamide adenine dinucleotide through cascades including the polyol pathway. This redox change is associated with insulin resistance and the development of diabetic complications, and might be counteracted by insulin C‐peptide. My research and others' suggest that the SIRT1–liver kinase B1–AMPK cascade creates positive feedback through nicotinamide adenine dinucleotide synthesis to help cells cope with metabolic stress. SIRT1 and AMPK can upregulate liver kinase B1 and FOXO3, key factors that help residential stem cells cope with oxidative stress. FOXO3 directly changes epigenetics around transcription start sites, maintaining the health of stem cells. ‘Diabetic memory’ is likely a result of epigenetic changes caused by high nutritional conditions, which disturb the quiescent state of residential stem cells and impair tissue repair. This could be prevented by restoring SIRT1–AMPK positive feedback through activating FOXO3.

Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss

Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.

Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss

Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.

Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss

Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.

Molecular mechanisms of diabetic retinopathy, general preventive strategies, and novel therapeutic targets

The growing number of people with diabetes worldwide suggests that diabetic retinopathy (DR) and diabetic macular edema (DME) will continue to be sight threatening factors. The pathogenesis of diabetic retinopathy is a widespread cause of visual impairment in the world and a range of hyperglycemia-linked pathways have been implicated in the initiation and progression of this condition. Despite understanding the polyol pathway flux, activation of protein kinase C (KPC) isoforms, increased hexosamine pathway flux, and increased advanced glycation end-product (AGE) formation, pathogenic mechanisms underlying diabetes induced vision loss are not fully understood. The purpose of this paper is to review molecular mechanisms that regulate cell survival and apoptosis of retinal cells and discuss new and exciting therapeutic targets with comparison to the old and inefficient preventive strategies. This review highlights the recent advancements in understanding hyperglycemia-induced biochemical and molecular alterations, systemic metabolic factors, and aberrant activation of signaling cascades that ultimately lead to activation of a number of transcription factors causing functional and structural damage to retinal cells. It also reviews the established interventions and emerging molecular targets to avert diabetic retinopathy and its associated risk factors.

Tonicity-responsive enhancer binding protein regulates the expression of aldose reductase and protein kinase C δ in a mouse model of diabetic retinopathy

Recent studies revealed that Tonicity-responsive enhancer binding protein (TonEBP) directly regulates the transcription of aldose reductase (AR), which catalyzes the first step of the polyol pathway of glucose metabolism. Activation of protein kinase C δ (PKCδ) is dependent on AR and it has been linked to diabetic complications. However, whether TonEBP affects expressions of AR and PKCδ in diabetic retinopathy was not clearly shown. In this study, we used TonEBP heterozygote mice to study the role of TonEBP in streptozotocin (STZ)-induced diabetic retinopathy. We performed immunofluorescence staining and found that retinal expressions of AR and PKCδ were significantly reduced in the heterozygotes compared to wild type littermates, particularly in ganglion cell layer. To examine further the effect of TonEBP reduction in retinal tissues, we performed intravitreal injection of TonEBP siRNA and confirmed the decrease in AR and PKCδ levels. In addition, we found that a proapoptotic factor, Bax level was reduced and a survival factor, Bcl2 level was increased after injection of TonEBP siRNA, indicating that TonEBP mediates apoptotic cell death. In parallel, TonEBP siRNA was applied to the in vitro human retinal pigment epithelial (ARPE-19) cells cultured in high glucose media. We have consistently found the decrease in AR and PKCδ levels and changes in apoptotic factors for survival. Together, these results clearly demonstrated that hyperglycemia-induced TonEBP plays a crucial role in increasing AR and PKCδ levels and leading to apoptotic death. Our findings suggest that TonEBP reduction is an effective therapeutic strategy for diabetic retinopathy.

Aldose reductase regulates miR-200a-3p/141-3p to coordinate Keap1-Nrf2, Tgfβ1/2, and Zeb1/2 signaling in renal mesangial cells and the renal cortex of diabetic mice

Aberrant regulation in oxidative stress, fibrogenesis, and the epithelial-mesenchymal transition (EMT) in renal cells under hyperglycemic conditions contributes significantly to the onset and progression of diabetic nephropathy. The mechanisms underlying these hyperglycemia-induced dysregulations, however, have not been clearly elucidated. Herein, we report that aldose reductase is capable of regulating the expression of miR-200a-3p/141-3p negatively in renal mesangial cells. MiR-200a-3p/141-3p, in turn, act to target Keap1, Tgfβ2, fibronectin, and Zeb2 directly and regulate Tgfβ1 and Nrf2 indirectly under high-glucose conditions, resulting in profound dysregulations in Keap1-Nrf2, Tgfβ1/2, and Zeb1/2 signaling. In vivo in streptozotocin-induced diabetic mice, we found that aldose reductase deficiency caused significant elevations in miR-200a-3p/141-3p in the renal cortex, which were accompanied by a significant downregulation of Keap1, Tgfβ1/2, and fibronectin but significant upregulation of Nrf2. Moreover, in vivo administration of inhibitors of miR-200a-3p in diabetic animals significantly exacerbated cortical and glomerular fibrogenesis and increased urinary albumin excretion, tightly linking dysregulated miR-200a-3p with the development of diabetic nephropathy. Collectively, our results reveal a novel mechanism whereby hyperglycemia induces aldose reductase to regulate renal expression of miR-200a-3p/141-3p to coordinately control hyperglycemia-induced renal oxidative stress, fibrogenesis, and the EMT. Our novel findings also suggest that inhibition of aldose reductase and in vivo renal cortical restoration of miR-200a-3p/141-3p or their combination are very promising avenues for the development of therapeutic strategies or drugs against diabetic nephropathy.

Rapid identification of aldose reductase inhibitory compounds from Perilla frutescens

The ethyl acetate (EtOAc) soluble fraction of methanol extracts of Perilla frutescens (P. frutescens) inhibits aldose reductase (AR), the key enzyme in the polyol pathway. Our investigation of inhibitory compounds from the EtOAc soluble fraction of P. frutescens was followed by identification of the inhibitory compounds by a combination of HPLC microfractionation and a 96-well enzyme assay. This allowed the biological activities to be efficiently matched with selected HPLC peaks. Structural analyses of the active compounds were performed by LC-MSⁿ. The main AR inhibiting compounds were tentatively identified as chlorogenic acid and rosmarinic acid by LC-MSⁿ. A two-step high speed counter current chromatography (HSCCC) isolation method was developed with a solvent system of n-hexane-ethyl acetate-methanol-water at 1.5 : 5 : 1 : 5, v/v and 3 : 7 : 5 : 5, v/v. The chemical structures of the isolated compounds were determined by ¹H- and ¹³C-nuclear magnetic resonance spectrometry (NMR). The main compounds inhibiting AR in the EtOAc fraction of methanol extracts of P. frutescens were identified as chlorogenic acid (2) (IC₅₀ = 3.16 μM), rosmarinic acid (4) (IC₅₀ = 2.77 μM), luteolin (5) (IC₅₀ = 6.34 μM), and methyl rosmarinic acid (6) (IC₅₀ = 4.03 μM).

Hypertensive Cardiac Remodeling Effects of Lignan Extracts from Eucommia ulmoides Oliv. Bark — A Famous Traditional Chinese Medicine

The lignan extracts from the tree bark of Eucommia ulmoides Oliv., a famous traditional Chinese medicine, have been demonstrated to have inhibitory effects on aldose reductase activity in spontaneously hypertensive rat myocardium. This study was aimed to investigate the hypertensive cardiac remodeling effects of the lignan extracts together with epalrestat. Ten-week-old male spontaneously hypertensive rats were randomly divided into three groups (n = 12, each) and administered 100 mg/kg/d of captopril (angiotensin converting enzyme inhibitor), 100 mg/kg/d of epalrestat (aldose reductase inhibitor) or 300 mg/kg/d of lignan extracts by gavage for 16 weeks. Sex-, age-, and number-matched normotensive Wistar Kyoto rats with spontaneously hypertensive rats were treated with distilled water (vehicle) as controls. Systolic blood pressures were measured periodically. Echocardiography examination was taken when rats were 24 weeks old. We found that both captopril and lignan extracts lowered blood pressure, and inhibited aldose reductase activity similarly to epalrestat. Echocardiography examination and histomorphometry indices were improved in all treated groups (p < 0.05). Therefore, lignan extracts could prevent hypertensive cardiac remodeling, which is likely related to aldose reductase inhibition.