The HDAC2/SP1/miR-205 feedback loop contributes to tubular epithelial cell extracellular matrix production in diabetic kidney disease.

Extracellular matrix (ECM) accumulation is considered an important pathological feature of diabetic kidney disease (DKD). Histone deacetylase (HDAC) inhibitors protect against kidney injury. However, the potential mechanisms of HDACs in DKD are still largely unknown. Here, we describe a novel feedback loop composed of HDAC2 and miR-205 that regulates ECM production in tubular epithelial cells in individuals with DKD. We found that HDAC2 mRNA expression in peripheral blood was markedly higher in patients with DKD than in patients with diabetes. Nuclear HDAC2 protein expression was increased in TGFß1-stimulated tubular epithelial cells and db/db mice. We also found that miR-205 was regulated by HDAC2 and down-regulated in TGFß1-treated HK2 cells and db/db mice. In addition, HDAC2 reduced histone H3K9 acetylation in the miR-205 promoter region to inhibit its promoter activity and subsequently suppressed miR-205 expression through an SP1-mediated pathway. Furthermore, miR-205 directly targeted HDAC2 and inhibited HDAC2 expression. Intriguingly, miR-205 also regulated its own transcription by inhibiting HDAC2 and increasing histone H3K9 acetylation in its promoter, forming a feedback regulatory loop. Additionally, the miR-205 agonist attenuated ECM production in HK2 cells and renal interstitial fibrosis in db/db mice. In conclusion, the HDAC2/SP1/miR-205 feedback loop may be crucial for the pathogenesis of DKD.

A spotlight on underlying the mechanism of AMPK in diabetes complications.

OBJECTIVE: Type 2 diabetes (T2D) is one of the centenarian metabolic disorders and is considered as a stellar and leading health issue worldwide. According to the International Diabetes Federation (IDF) Diabetes Atlas and National Diabetes Statistics, the number of diabetic patients will increase at an exponential rate from 463 to 700 million by the year 2045. Thus, there is a great need for therapies targeting functions that can help in maintaining the homeostasis of glucose levels and improving insulin sensitivity. 5' adenosine monophosphate-activated protein kinase (AMPK) activation, by various direct and indirect factors, might help to overcome the hurdles (like insulin resistance) associated with the conventional approach. MATERIALS AND RESULTS: A thorough review and analysis was conducted using various database including MEDLINE and EMBASE databases, with Google scholar using various keywords. This extensive review concluded that various drugs (plant-based, synthetic indirect/direct activators) are available, showing tremendous potential in maintaining the homeostasis of glucose and lipid metabolism, without causing insulin resistance, and improving insulin sensitivity. Moreover, these drugs have an effect against diabetes and are therapeutically beneficial in the treatment of diabetes-associated complications (neuropathy and nephropathy) via mechanism involving inhibition of nuclear translocation of SMAD4 (SMAD family member) expression and association with peripheral nociceptive neurons mediated by AMPK. CONCLUSION: From the available information, it may be concluded that various indirect/direct activators show tremendous potential in maintaining the homeostasis of glucose and lipid metabolism, without resulting in insulin resistance, and may improve insulin sensitivity, as well. Therefore, in a nut shell, it may be concluded that the regulation of APMK functions by various direct/indirect activators may bring promising results. These activators may emerge as a novel therapy in diabetes and its associated complications.

Oxymatrine Ameliorates Memory Impairment in Diabetic Rats by Regulating Oxidative Stress and Apoptosis: Involvement of NOX2/NOX4.

Oxymatrine (OMT) is the major quinolizidine alkaloid extracted from the root of Sophora flavescens Ait and has been shown to exhibit a diverse range of pharmacological properties. The aim of the present study was to investigate the role of OMT in diabetic brain injury in vivo and in vitro. Diabetic rats were induced by intraperitoneal injection of a single dose of 65 mg/kg streptozotocin (STZ) and fed a high-fat and high-cholesterol diet. Memory function was assessed using a Morris water maze test. A SH-SY5Y cell injury model was induced by incubation with glucose (30 mM/l) to simulate damage in vitro. The serum fasting blood glucose, insulin, serum S100B, malondialdehyde (MDA), and superoxide dismutase (SOD) levels were analyzed using commercial kits. Morphological changes were observed using Nissl staining and electron microscopy. Cell apoptosis was assessed using Hoechst staining and TUNEL staining. NADPH oxidase (NOX) and caspase-3 activities were determined. The effects of NOX2 and NOX4 knockdown were assessed using small interfering RNA. The expression levels of NOX1, NOX2, and NOX4 were detected using reverse transcription-quantitative PCR and western blotting, and the levels of caspase-3 were detected using western blotting. The diabetic rats exhibited significantly increased plasma glucose, insulin, reactive oxygen species (ROS), S-100B, and MDA levels and decreased SOD levels. Memory function was determined by assessing the percentage of time spent in the target quadrant, the number of times the platform was crossed, escape latency, and mean path length and was found to be significantly reduced in the diabetic rats. Hyperglycemia resulted in notable brain injury, including histological changes and apoptosis in the cortex and hippocampus. The expression levels of NOX2 and NOX4 were significantly upregulated at the protein and mRNA levels, and NOX1 expression was not altered in the diabetic rats. NOX and caspase-3 activities were increased, and caspase-3 expression was upregulated in the brain tissue of diabetic rats. OMT treatment dose-dependently reversed behavioral, biochemical, and molecular changes in the diabetic rats. In vitro, high glucose resulted in increases in reactive oxygen species (ROS), MDA levels, apoptosis, and the expressions of NOX2, NOX4, and caspase-3. siRNA-mediated knockdown of NOX2 and NOX4 decreased NOX2 and NOX4 expression levels, respectively, and reduced ROS levels and apoptosis. The results of the present study suggest that OMT alleviates diabetes-associated cognitive decline, oxidative stress, and apoptosis via NOX2 and NOX4 inhibition.

Design, microwave synthesis, and molecular docking studies of catalpol crotonates as potential neuroprotective agent of diabetic encephalopathy.

Catalpol has gained increasing attention for its potential contributions in controlling glycolipid metabolism and diabetic complications, which makes used as a very promising scaffold for seeking new anti-diabetic drug candidates. Acylation derivatives of catalpol crotonate (CCs) were designed as drug ligands of glutathione peroxidase (GSH-Px) based on molecular docking (MD) using Surfex-Docking method. Catalpol hexacrotonate (CC-6) was synthesized using microwave assisted method and characterized by FT-IR, NMR, HPLC and HRMS. The MD results indicate that with the increasing of esterification degree of hydroxyl, the C log P of CCs increased significantly, and the calculated total scores (Total_score) of CCs are all higher than that of catalpol. It shows that CCs maybe served as potential lead compounds for neuroprotective agents. It was found that the maximum Total_score of isomers in one group CCs is often not that the molecule with minimum energy. MD calculations show that there are five hydrogen bonds formed between CC-6 and the surrounding amino acid residues. Molecular dynamics simulation results show that the binding of CC-6 with GSH-Px is stable. CC-6 was screened for SH-SY5Y cells viability by MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay, the result indicates CC-6 can effectively reverse SZT induced cells apoptosis with dose-dependent manner, which can indirectly show that CC-6 is a potential neuroprotective agent.

Loss of PARP-1 attenuates diabetic arteriosclerotic calcification via Stat1/Runx2 axis.

Accelerated atherosclerotic calcification is responsible for plaque burden, especially in diabetes. The regulatory mechanism for atherosclerotic calcification in diabetes is poorly characterized. Here we show that deletion of PARP-1, a main enzyme in diverse metabolic complications, attenuates diabetic atherosclerotic calcification and decreases vessel stiffening in mice through Runx2 suppression. Specifically, PARP-1 deficiency reduces diabetic arteriosclerotic calcification by regulating Stat1-mediated synthetic phenotype switching of vascular smooth muscle cells and macrophage polarization. Meanwhile, both vascular smooth muscle cells and macrophages manifested osteogenic differentiation in osteogenic media, which was attenuated by PARP-1/Stat1 inhibition. Notably, Stat1 acts as a positive transcription factor by directly binding to the promoter of Runx2 and promoting atherosclerotic calcification in diabetes. Our results identify a new function of PARP-1, in which metabolism disturbance-related stimuli activate the Runx2 expression mediated by Stat1 transcription to facilitate diabetic arteriosclerotic calcification. PARP-1 inhibition may therefore represent a useful therapy for this challenging complication.

An Overview on ATP Dependent and Independent Proteases Including an Anterograde to Retrograde Control on Mitochondrial Function; Focus on Diabetes and Diabetic Complications.

Mitochondria are the central power stations of the cell involved with a myriad of cell signalling pathways that contribute for whole health status of the cell. It is a well known fact that not only mitochondrial genome encodes for mitochondrial proteins but there are several other mitochondrial specific proteins encoded by nuclear genome which regulate plethora of cell catabolic and anabolic process. Anterograde pathways include nuclear gene encoded proteins and their specific transport into the mitochondria and regulation of mitochondrial homeostasis. The retrograde pathways include crosstalk between the mitochondria and cytoplasmic proteins. Indeed, ATP dependent and independent proteases are identified to be very critical in balancing anterograde to retrograde signalling and vice versa to maintain the cell viability or cell death. Different experimental studies conducted on silencing the genes of these proteases have shown embryonic lethality, cancer cells death, increased hepatic glucose output, insulin tolerance, increased protein exclusion bodies, mitochondrial dysfunction, and defect in mitochondrial biogenesis, increased inflammation, Apoptosis etc. These experimental studies included from eubacteria to eukaryotes. Hence, many lines of theories proposed these proteases are conservative from eubacteria to eukaryotes. However, the regulation of these proteases at gene level is not clearly understood and still research is warranted. In this review, we articulated the origin and regulation of these proteases and the cross talk between the nucleus and mitochondria vice versa, and highlighted the role of these proteases in diabetes and diabetic complications in human diseases.

The Effects of Trimetazidine on QT-interval Prolongation and Cardiac Hypertrophy in Diabetic Rats / Os Efeitos da Trimetazidina no Prolongamento do Intervalo QT e na Hipertrofia Cardíaca em Ratos Diabéticos

Abstract Background: Trimetazidine (TMZ) is an anti-ischemic drug. In spite of its protective effects on cardiovascular system, there is no scientific study on the usefulness of TMZ treatment for prolonged QT interval and cardiac hypertrophy induced by diabetes. Objectives: To evaluate the effects of TMZ on QT interval prolongation and cardiac hypertrophy in the diabetic rats. Methods: Twenty-four male Sprague-Dawley rats (200-250 g) were randomly assigned into three groups (n = 8) by simple random sampling method. Control (C), diabetic (D), and diabetic administrated with TMZ at 10 mg/kg (T10). TMZ was administrated for 8 weeks. The echocardiogram was recorded before isolating the hearts and transfer to a Langendorff apparatus. Hemodynamic parameters, QT and corrected QT interval (QTc) intervals, heart rate and antioxidant enzymes were measured. The hypertrophy index was calculated. The results were evaluated by one-way ANOVA and paired t-test using SPSS (version 16) and p < 0.05 was regarded as significant. Results: The diabetic rats significantly indicated increased hypertrophy, QT and QTc intervals and decreased Left ventricular systolic pressure (LVSP), Left ventricular developed pressure (LVDP), rate pressure product (RPP), Max dp/dt, and min dp/dt (±dp/dt max), heart rate, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase in the heart. Treatment with TMZ in the diabetic animals was significantly improved these parameters in comparison to the untreated diabetic group. Conclusions: TMZ improves QTc interval prolongation and cardiac hypertrophy in diabetes.

Resumo Fundamento: A trimetazidina (TMZ) é uma droga anti-isquêmica. Apesar de seus efeitos protetores sobre o sistema cardiovascular, não há estudos científicos sobre a utilidade do tratamento com TMZ para o intervalo QT prolongado e a hipertrofia cardíaca induzida pelo diabetes. Objetivo: Avaliar os efeitos da TMZ no prolongamento do intervalo QT e na hipertrofia cardíaca em ratos diabéticos. Métodos: Vinte e quatro ratos machos Sprague-Dawley (200-250 g) foram distribuídos aleatoriamente em três grupos (n = 8) pelo método de amostragem aleatória simples. Controle (C), diabético (D) e diabético administrado com TMZ a 10 mg/kg (T10). A TMZ foi administrada por 8 semanas. O ecocardiograma foi registrado antes de isolar os corações e transferir para um aparelho de Langendorff. Foram medidos os parâmetros hemodinâmicos, intervalo QT e intervalo QT corrigido (QTc), frequência cardíaca e enzimas antioxidantes. O índice de hipertrofia foi calculado. Os resultados foram avaliados pelo one-way ANOVA e pelo teste t pareado pelo SPSS (versão 16) e p < 0,05 foi considerado significativo. Resultados: Os ratos diabéticos indicaram hipertrofia aumentada, intervalos QT e QTc e diminuição da pressão sistólica no ventrículo esquerdo (PSVE), pressão desenvolvida no ventrículo esquerdo (PDVE), duplo produto (DP), Max dp/dt e min dp/dt (± dp/dt max), frequência cardíaca, superóxido dismutase (SOD), glutationa peroxidase (GPx) e catalase no coração. O tratamento com TMZ nos animais diabéticos melhorou significativamente esses parâmetros em comparação com o grupo diabético não tratado. Conclusões: A TMZ melhora o prolongamento do intervalo QTc e a hipertrofia cardíaca no diabetes.

Reactions between methylglyoxal and its scavengers in-vivo appear to be catalyzed enzymatically.

Methylglyoxal (MGO) is thought to be an important contributor to the development of diabetic complications. In this paper I propose that MGO, not detoxified by the glyoxalase system, is removed from circulation by MGO-scavengers. Furthermore, since intrinsic rates of reactions between MGO and its scavengers are low, I propose that, in-vivo, these reactions are catalyzed enzymatically.

Cyclooxygenase 2 contributes to bradykinin-induced microvascular responses in peripheral arterioles after cardiopulmonary bypass.

BACKGROUND: Diabetic patients are associated with impaired peripheral microvascular function after cardiopulmonary bypass (CPB) and cardiac surgery. We hypothesized that upregulation of the inducible cyclooxygenase 2 (COX-2) contributes to altered microvascular reactivity of peripheral arterioles in diabetic patients undergoing CPB and cardiac surgery. METHODS: Skeletal muscle samples of nondiabetic (ND) patients and patients with diabetes mellitus (DM; n = 8 per group) undergoing cardiac surgery were harvested before and after CPB. The protein expression/localization of COX-2 was assayed by Western blotting and immunohistochemistry. Peripheral arterioles were dissected from the harvested skeletal muscle tissue samples, the isolated arterioles (80-180 µm) were cannulated and pressurized, and changes in diameter were measured with video microscopy. In-vitro relaxation responses of precontracted arterioles were examined in the presence of the endothelium-dependent vasodilator bradykinin (10-10 to 10-6M) and in the presence or absence of the selective COX-2 inhibitor NS398 (10-5M). RESULTS: The post-CPB protein levels of the inducible COX-2 were significantly increased compared with pre-CPB values in both the ND and DM groups (P < 0.05), whereas, this increase was higher in DM than that of ND (P < 0.05). In the DM arterioles, not the ND vessels, bradykinin-induced relaxation response was inhibited in the presence of the specific COX-2 inhibitor NS398 at baseline (P < 0.05). After CPB, bradykinin-induced relaxation response of the ND and DM arterioles was inhibited in the presence of the specific COX-2 inhibitor NS398, but this effect was more pronounced in the diabetic patients (P < 0.05). CONCLUSIONS: Diabetes and CPB are associated with upregulation in COX-2 expression/activation in human peripheral microvasculature. This alteration may lead to altered peripheral microvascular reactivity in diabetic patients undergoing cardiac surgery.

Matrix Metalloproteinase-1 and Matrix Metalloproteinase-9 in the Aqueous Humor of Diabetic Macular Edema Patients.

PURPOSE: To assess the concentrations of matrix metalloproteinase (MMP)-1 and MMP-9 in the aqueous humor of diabetic macular edema (DME) patients. METHOD: The concentrations of MMP-1 and MMP-9 in the aqueous humors of 15 cataract patients and 25 DME patients were compared. DME patients were analyzed according to the diabetic retinopathy (DR) stage, diabetes mellitus (DM) duration, pan-retinal photocoagulation (PRP) treatment, recurrence within 3 months, HbA1C (glycated hemoglobin) level, and axial length. RESULTS: The concentrations of MMP-1 and MMP-9 of the DME groups were higher than those of the control group (p = 0.005 and p = 0.002, respectively). There was a significant difference in MMP-1 concentration between the mild non-proliferative diabetic retinopathy (NPDR) group and the proliferative diabetic retinopathy (PDR) group (p = 0.012). MMP-1 concentrations were elevated in PRP-treated patients (p = 0.005). There was a significant difference in MMP-9 concentrations between the mild NPDR group and the PDR group (p < 0.001), and between the moderate and severe NPDR group and the PDR group (p < 0.001). The MMP-9 concentrations in PRP treated patients, DM patients with diabetes ≥ 10 years and recurrent DME within 3months were elevated (p = 0.023, p = 0.011, and p = 0.027, respectively). In correlation analyses, the MMP-1 level showed a significant correlation with age (r = -0.48, p = 0.01,), and the MMP-9 level showed significant correlations with axial length (r = -0.59, p < 0.01) and DM duration (r = 049, p = 0.01). CONCLUSIONS: Concentrations of MMP-1 and MMP-9 were higher in the DME groups than in the control group. MMP-9 concentrations also differed depending on DR staging, DM duration, PRP treatment, and degree of axial myopia. MMP-9 may be more important than MMP-1 in the induction of DM complications in eyes.

Sulforaphane ameliorates the insulin responsiveness and the lipid profile but does not alter the antioxidant response in diabetic rats.

Diabetes is one of the most prevalent chronic non-communicable diseases and is characterized by hyperglycemia and increased oxidative stress. These two alterations are also responsible for the main diabetic complications: cardiovascular disease, retinopathy, nephropathy and peripheral neuropathy. Diabetes progression is governed by pancreatic ß-cell failure, and recent studies showed that sulforaphane (SFN) might be able to prevent this change, preserving insulin production. Consequently, our goal was to test the effects of SFN on metabolic parameters related to diabetic complications and antioxidant defenses (superoxide dismutase, catalase and sulfhydryl groups) in the pancreas, liver and kidney of non-diabetic and diabetic rats. Male Wistar rats were treated with water or 0.5 mg kg(-1) SFN i.p. for 21 days after diabetes induction. In diabetic animals treated with SFN, the serum levels of total cholesterol, non-HDL cholesterol and triacylglycerols were similar to those of non-diabetic animals, and the insulin responsiveness was higher than that of the diabetic animals that did not receive the compound. No effect of SFN on the superoxide dismutase and catalase activity or sulfhydryl groups was observed in the pancreas, liver or kidney of the treated animals. We conclude that SFN ameliorates some features of clinical diabetic complications particularly the lipid profile and insulin responsiveness, but it does not modulate the antioxidant response induced by superoxide dismutase, catalase and sulfhydryl groups in the evaluated organs.

Lysyl Oxidase Isoforms and Potential Therapeutic Opportunities for Fibrosis and Cancer.

INTRODUCTION: The lysyl oxidase family of enzymes is classically known as being required for connective tissue maturation by oxidizing lysine residues in elastin and lysine and hydroxylysine residues in collagen precursors. The resulting aldehydes then participate in cross-link formation, which is required for normal connective tissue integrity. These enzymes have biological functions that extend beyond this fundamental biosynthetic role, with contributions to angiogenesis, cell proliferation, and cell differentiation. Dysregulation of lysyl oxidases occurs in multiple pathologies including fibrosis, primary and metastatic cancers, and complications of diabetes in a variety of tissues. AREAS COVERED: This review summarizes the major findings of novel roles for lysyl oxidases in pathologies, and highlights some of the potential therapeutic approaches that are in development and which stem from these new findings. EXPERT OPINION: Fundamental questions remain regarding the mechanisms of novel biological functions of this family of proteins, and regarding functions that are independent of their catalytic enzyme activity. However, progress is underway in the development of isoform-specific pharmacologic inhibitors, potential therapeutic antibodies and gaining an increased understanding of both tumor suppressor and metastasis promotion activities. Ultimately, this is likely to lead to novel therapeutic agents.

Essential oil of Zygophyllum album inhibits key-digestive enzymes related to diabetes and hypertension and attenuates symptoms of diarrhea in alloxan-induced diabetic rats.

CONTEXT: Zygophyllum album L. (Zygophyllaceae), commonly known as Bougriba, is widely used to treat diabetes, digestive tract spasm, and hypertension in folk medicine, in Tunisia. OBJECTIVE: This study investigates the antidiabetic, antidiarrheal, and antihypertensive activities of the leaves of the essential oil from Zygophyllum album (OZA) in alloxan-induced diabetic rats. MATERIALS AND METHODS: The oil was obtained by hydrodistillation and analyzed by GC-MS. Males rats were divided into four groups: control, diabetic-untreated group, diabetic-treated group with acarbose (10 mg/kg), and diabetic-treated rats with OZA (200 mg/kg) for 30 d. RESULTS: At the end of the experimental period, the OZA significantly decreased the activity of α-amylase in pancreas and serum of the diabetic rats by 43% and 38%, respectively, which led to reduce the serum glucose level by 60% and lower of glycated hemoglobin (HbA1c) rate by 17% as compared with untreated diabetic animals. Moreover, the OZA treatment attenuated symptoms of diarrhea, improved lipid disorders, and hypertension through inhibiting the pancreatic lipase and angiotensin-converting enzyme (ACE) activities by 47% and 25%, respectively, in serum of diabetic rats. CONCLUSION: OZA showed a good effect in the management of diabetes mellitus and exerted preventive action from related hypertension.

Association of Genetically Determined Aldehyde Dehydrogenase 2 Activity with Diabetic Complications in Relation to Alcohol Consumption in Japanese Patients with Type 2 Diabetes Mellitus: The Fukuoka Diabetes Registry.

Aldehyde dehydrogenase 2 (ALDH2) detoxifies aldehyde produced during ethanol metabolism and oxidative stress. A genetic defect in this enzyme is common in East Asians and determines alcohol consumption behaviors. We investigated the impact of genetically determined ALDH2 activity on diabetic microvascular and macrovascular complications in relation to drinking habits in Japanese patients with type 2 diabetes mellitus. An ALDH2 single-nucleotide polymorphism (rs671) was genotyped in 4,400 patients. Additionally, the relationship of clinical characteristics with ALDH2 activity (ALDH2 *1/*1 active enzyme activity vs. *1/*2 or *2/*2 inactive enzyme activity) and drinking habits (lifetime abstainers vs. former or current drinkers) was investigated cross-sectionally (n = 691 in *1/*1 abstainers, n = 1,315 in abstainers with *2, n = 1,711 in *1/*1 drinkers, n = 683 in drinkers with *2). The multiple logistic regression analysis for diabetic complications was adjusted for age, sex, current smoking habits, leisure-time physical activity, depressive symptoms, diabetes duration, body mass index, hemoglobin A1c, insulin use, high-density lipoprotein cholesterol, systolic blood pressure and renin-angiotensin system inhibitors use. Albuminuria prevalence was significantly lower in the drinkers with *2 than that of other groups (odds ratio [95% confidence interval (CI)]: *1/*1 abstainers as the referent, 0.94 [0.76-1.16] in abstainers with *2, 1.00 [0.80-1.26] in *1/*1 drinkers, 0.71 [0.54-0.93] in drinkers with *2). Retinal photocoagulation prevalence was also lower in drinkers with ALDH2 *2 than that of other groups. In contrast, myocardial infarction was significantly increased in ALDH2 *2 carriers compared with that in ALDH2 *1/*1 abstainers (odds ratio [95% CI]: *1/*1 abstainers as the referent, 2.63 [1.28-6.13] in abstainers with *2, 1.89 [0.89-4.51] in *1/*1 drinkers, 2.35 [1.06-5.79] in drinkers with *2). In summary, patients with type 2 diabetes and ALDH2 *2 displayed a lower microvascular complication prevalence associated with alcohol consumption but a higher macrovascular complication prevalence irrespective of alcohol consumption.

Synthesis and Biological Evaluation of Novel Gigantol Derivatives as Potential Agents in Prevention of Diabetic Cataract.

As a continuation of our efforts directed towards the development of natural anti-diabetic cataract agents, gigantol was isolated from Herba dendrobii and was found to inhibit both aldose reductase (AR) and inducible nitric oxide synthase (iNOS) activity, which play a significant role in the development and progression of diabetic cataracts. To improve its bioefficacy and facilitate use as a therapeutic agent, gigantol (compound 14f) and a series of novel analogs were designed and synthesized. Analogs were formulated to have different substituents on the phenyl ring (compounds 4, 5, 8, 14a-e), substitute the phenyl ring with a larger steric hindrance ring (compounds 10, 17c) or modify the carbon chain (compounds 17a, 17b, 21, 23, 25). All of the analogs were tested for their effect on AR and iNOS activities and on D-galactose-induced apoptosis in cultured human lens epithelial cells. Compounds 5, 10, 14a, 14b, 14d, 14e, 14f, 17b, 17c, 23, and 25 inhibited AR activity, with IC50 values ranging from 5.02 to 288.8 µM. Compounds 5, 10, 14b, and 14f inhibited iNOS activity with IC50 ranging from 432.6 to 1188.7 µM. Compounds 5, 8, 10, 14b, 14f, and 17c protected the cells from D-galactose induced apoptosis with viability ranging from 55.2 to 76.26%. Of gigantol and its analogs, compound 10 showed the greatest bioefficacy and is warranted to be developed as a therapeutic agent for diabetic cataracts.

Expression of SIRT1 and oxidative stress in diabetic dry eye.

OBJECTIVE: To explore the expression of SIRT1 with oxidative stress and observe physiological and pathological changes in the corneas as well as the association between SIRT1 and oxidative stress of diabetic dry eyes in mice. METHOD: Forty-eight C57BL/6Jdb/db mice at eight weeks of age were divided randomly into two groups: the diabetic dry eye group and the diabetic group. An additional forty-eight C57BL/6J mice at eight weeks of age were divided randomly into two groups: the dry eye group and the control group. Every mouse in the dry eye groups (diabetic and normal) was injected with scopolamine hydrobromide three times daily, combined with low humidity to establish a dry eye model. After the intervention, phenol red cotton string tests and corneal fluorescein staining were performed. In addition, HE staining and immunofluorescence were done. Expression of SIRT1 in the cornea was examined by real-time PCR and Western Blot and expression of FOXO3 and MnSOD proteins was detected by Western Blot. RESULTS: At one, four, and eight weeks post intervention, all of the groups except the controls showed significant decreases in tear production and increases in the corneal fluorescein stain (P<0.05 vs control). Between the experimental groups, the diabetic dry eye group had the least tear production and the highest corneal fluorescein stain score (P<0.05). As the disease progressed, all of the experimental groups showed obviously pathological changes in HE staining, particularly the diabetic dry eye group. In the 1(st) and 4(th) week, the expression of SIRT1, FOXO3, and MnSOD were significantly higher in the diabetic DE and DM groups but lower in the DE group compared to the controls (P<0.05). In the 8(th) week, the expression of SIRT1, FOXO3, and MnSOD was significantly down-regulated in the diabetic DE group and the DM group (P<0.05). Immunofluorescence showed similar results. CONCLUSION: In the condition of diabetic dry eye, tear production declined markedly coupled with seriously wounded corneal epithelium. Oxidative stress in the cornea was enhanced significantly and the expression of SIRT1 was decreased.

Monoamine Oxidases as Potential Contributors to Oxidative Stress in Diabetes: Time for a Study in Patients Undergoing Heart Surgery.

Oxidative stress is a pathomechanism causally linked to the progression of chronic cardiovascular diseases and diabetes. Mitochondria have emerged as the most relevant source of reactive oxygen species, the major culprit being classically considered the respiratory chain at the inner mitochondrial membrane. In the past decade, several experimental studies unequivocally demonstrated the contribution of monoamine oxidases (MAOs) at the outer mitochondrial membrane to the maladaptative ventricular hypertrophy and endothelial dysfunction. This paper addresses the contribution of mitochondrial dysfunction to the pathogenesis of heart failure and diabetes together with the mounting evidence for an emerging role of MAO inhibition as putative cardioprotective strategy in both conditions.

Macrophages in diabetic gastroparesis--the missing link?

BACKGROUND: Diabetic gastroparesis results in significant morbidity for patients and major economic burden for society. Treatment options for diabetic gastroparesis are currently directed at symptom control rather than the underlying disease and are limited. The pathophysiology of diabetic gastroparesis includes damage to intrinsic and extrinsic neurons, smooth muscle, and interstitial cells of Cajal (ICC). Oxidative damage in diabetes appears to be one of the primary insults involved in the pathogenesis of several complications of diabetes, including gastroparesis. Recent studies have highlighted the potential role of macrophages as key cellular elements in the pathogenesis of diabetic gastroparesis. Macrophages are important for both homeostasis and defense against a variety of pathogens. Heme oxygenase 1 (HO1), an enzyme expressed in a subset of macrophages has emerged as a major protective mechanism against oxidative stress. Activation of macrophages with high levels of HO1 expression protects against development of delayed gastric emptying in animal models of diabetes, while activation of macrophages that do not express HO1 are linked to neuromuscular cell injury. Targeting macrophages and HO1 may therefore be a therapeutic option in diabetic gastroparesis. PURPOSE: This report briefly reviews the pathophysiology of diabetic gastroparesis with a focus on oxidative damage and how activation and polarization of different subtypes of macrophages in the muscularis propria determines development of delay in gastric emptying or protects against its development.

Xanthine oxidoreductase in atherosclerosis pathogenesis: not only oxidative stress.

Endothelial xanthine oxidoreductase (XOR) together with NAD(P)H oxidase and nitric oxide (NO) synthase plays a physiologic role in inflammatory signalling, the regulation of NO production and vascular function. The oxidative stress generated by these enzymes may induce endothelial dysfunction, leading to atherosclerosis, cardiovascular diseases and metabolic syndrome. XOR activity creates both oxidant and anti-oxidant products that are implicated in the development of hypertension, smoking vascular injury, dyslipidemia and diabetes, which are the main risk factors of atherosclerosis. In particular, uric acid may have a protective as well as a detrimental role in vascular alterations, thus justifying the multi-directional effects of XOR inhibition. Moreover, XOR products are associated with cell differentiation, leading to adipogenesis and foam cell formation, as well as to the production of monocyte chemoattractant protein-1 from arterial smooth muscle cells, after proliferation and migration. The role of XOR in adipogenesis is also connected with insulin resistance and obesity, two main features of type 2 diabetes.

Extracts and compounds with anti-diabetic complications and anti-cancer activity from Castanea mollissina Blume (Chinese chestnut).

BACKGROUND: Castanea mollissima Blume (Chinese chestnut), as a food product is known for its various nutrients and functional values to the human health. The present study was carried out to analyze the anti-diabetic complications and anti-cancer activities of the bioactive compounds present in C. mollissima. METHODS: The kernels (CK), shells (CS) and involucres (CI) parts of C. Blume were extracted with 90% alcohol. The water suspension of these dried alcohol extracts were extracted using EtOAc and n-BuOH successively. The n-BuOH fraction of CI (CI-B) was isolated by silica gel column, Sephadex LH 20 column and preparative HPLC. The isolated compounds were identified by 1H-NMR, 13C-NMR, HMBC, HMQC and ESI-Q-TOF MS, All the fractions and compounds isolated were evaluated on human recombinant aldose reductase (HR-AR) assay, advanced glycation end products (AGEs) formation assay and human COLO 320 DM colon cancer cells inhibitory assay. RESULTS: CI-B was found to show a significant inhibitory effect in above biological screenings. Six flavonoids and three polyphenolic acids were obtained from CI-B. They were identified as kaempferol (1), kaempferol-3-O-[6''-O-(E)-p-coumaroyl]-ß-D-glucopyranoside (2), kaempferol-3-O-[6''-O-(E)-p-coumaroyl]-ß-D-galactopyranoside (3), kaempferol-3-O-[2''-O-(E)-p-coumaroyl]-ß-D-glucopyranoside (4), kaempferol-3-O-[2", 6"-di-O-(E)-p-coumaroyl]-ß-D-glucopyranoside (5) and kaempferol-3-O-[2", 6"-di-O-(E)-p-coumaroyl]-ß-D-galactopyranoside (6), casuariin (7), casuarinin (8) and castalagin (9). Compounds 2-9 were found to show higher activity than quercetin (positive control) in the AR assay. Compounds 3-6, 8, and 9 showed stronger inhibitory effects than amino guanidine (positive control) on AGEs production. Compounds 4-6, 7, and 8 showed much higher cytotoxic activity than 5-fluorouracil (positive control) against the human COLO 320 DM colon cancer cells. CONCLUSIONS: Our results suggest that flavonoids and polyphenolic acids possesses anti-diabetes complications and anti-cancer properties, and they were presumed to be the bioactive components of Castanea mollissima Blume.