New 1,4-Dihydropyridines Down-regulate Nitric Oxide in Animals with Streptozotocin-induced Diabetes Mellitus and Protect Deoxyribonucleic Acid against Peroxynitrite Action

Evaluation of the anti-inflammatory effect of 1,4-dihydropyridine derivatives

INTRODUCTION

Inflammation is a physiological event that protects the organism against different factors that lead to loss of tissue homeostasis. Dihydropyridine (DHP) derivatives are heterocyclic compounds known for their different biological activities, including anti-inflammatory activities.

OBJECTIVE

To evaluate the anti-inflammatory activity of 1,4-dihydropyridine (1,4-DHP) derivatives using anti-inflammatory models in vitro, in RAW264.7 cells induced by lipopolysaccharide (LPS) and in vivo using the acute lung injury (ALI) model in mice.

RESULTS

Fifteen compounds derived from 1,4-DHP were tested in RAW264.7 cells for their cytotoxic effect and cell viability. Thereafter, only the six compounds that showed the highest cell viability were tested for the production or inhibition of the pro-inflammatory cytokine interleukin 6 (IL-6). The best compound (compound 4) was tested for its anti-inflammatory effects in vitro and in vivo, showing inhibition of nitric oxide (NO), pro-inflammatory cytokines, increased phagocytic activity, and an increase in IL-10 in vitro. In in vivo tests, compound 4 also reduces the levels of NO, myeloperoxidase (MPO) activity, leukocyte migration, and exudation, as well as reducing the levels of tumor necrosis factor-alpha (TNF-α) and IL-6 and preventing the loss in the lung architecture.

CONCLUSION

This compound showed important anti-inflammatory activity, with a significant ability to reduce the production of pro-inflammatory mediators and increase the phagocytic activity of macrophages and anti-inflammatory mediator secretion (IL-10). These findings led us to hypothesize that this compound can repolarize the macrophage response to an anti-inflammatory profile (M2). Moreover, it was also able to maintain its anti-inflammatory activity in vivo experiments.

Genotoxic and genoprotective effects of 1,4-dihydropyridine derivatives: a brief review

This review summarises current knowledge about the genotoxic and genoprotective effects of 1,4-dihydropyridines (DHP) with the main focus on the water-soluble 1,4-DHPs. Most of these water-soluble compounds manifest very low calcium channel blocking activity, which is considered "unusual" for 1,4-DHPs. Glutapyrone, diludine, and AV-153 decrease spontaneous mutagenesis and frequency of mutations induced by chemical mutagens. AV-153, glutapyrone, and carbatones protect DNA against the damage produced by hydrogen peroxide, radiation, and peroxynitrite. The ability of these molecules to bind to the DNA may not be the only mechanism of DNA protection, as other mechanisms such as radical scavenging or binding to other genotoxic compounds may take place and enhance DNA repair. These uncertainties and reports of high 1,4-DHP concentrations damaging the DNA call for further in vitro and in vivo preclinical research, pharmacokinetic in particular, as it can help pinpoint the exact mechanism(s) of the genotoxic and/or genoprotective action of 1,4-DHPs.

Immunohistochemical Expression Pattern of Mismatch Repair Genes in the Short-term Streptozotocin-induced Diabetic Rat Kidneys

We studied the expression of mismatch repair genes (MMRs)-mutS protein homolog 2 (MSH2), PMS2, MutL homolog 1 (MLH1), and yH2AFX in diabetic rat kidneys. Streptozotocin-induced diabetes mellitus type 1 rat model (DM1) was used. Renal samples were collected 2 weeks and 2 months after DM1 induction and immunohistochemical expression of MMR genes in the renal cortex was analyzed. Diabetic animals showed lower MSH2 and higher yH2AFX kidney expression both 2 weeks and 2 months after DM1 induction. MLH1 expression significantly increased 2 weeks after DM1 induction (P<0.0001). The most substantial differences were observed in the period 2 weeks after induction, with lower MSH2 and higher MLH1 expression in the proximal convoluted tubules and distal convoluted tubules (DCT) of diabetic animals (P<0.001). yH2AFX expression significantly increased in the DCT of diabetic animals at both time points (P<0.001; P<0.01). PMS2 expression changed only in the glomeruli, where it significantly decreased 2 months after DM1 induction (P<0.05). We concluded that the most substantial changes in renal expression of MMRs are happening already 2 weeks after diabetes induction, predominantly in the proximal convoluted tubules and DCT. Moreover, DCT could have a critical role in the pathophysiology of diabetic nephropathy (DN) and might be a future therapeutic target in this condition. The obtained results point to the MMRs as a potential factor in the development and progression of DN, as well as the possible link between DN and renal carcinogenesis.

DNA-binding activities of compounds acting as enzyme inhibitors, ion channel blockers and receptor binders

The DNA-binding activities of compounds used as remedies can display DNA-protection, but also damaging effects in biological systems. The current review compiles literature data on DNA-binding activities of drugs widely used as remedies with different therapeutic indications. The compounds are classified according their mechanism of action: enzyme inhibitors, ion channel inhibitors, inhibitors of viral RNA replication and HIV protease and receptor agonists. DNA binding was reported for such widely used drugs as paracetamol, aspirin, metformin, statins and many others. The capability of the drug to bind DNA is sometimes coupled to genotoxic effects, but in some cases - to genome protection. Data on atoms and chemical groups involved in the drug-DNA interactions are also presented. In many cases the same atoms are involved in both interactions of the compounds with proteins and DNA.

Nitric oxide metabolism is impaired by type 1 diabetes and diabetic nephropathy

Diabetes leads to reduced nitric oxide bioavailability, resulting in endothelial dysfunction. However, overproduction of nitric oxide due to hyperglycaemia is associated with oxidative stress and tissue damage. The objective of this study was to characterise nitric oxide production (NO) and added nitrite and nitrate (NO₂ ^-+NO₃ ^-) concentration in the blood and urine of patients with and without diabetic nephropathy. A total of 268 patients with type 1 diabetes and 69 healthy subjects were included. Diabetic nephropathy was defined as macroalbuminuria and/or estimated glomerular filtration rate below 60 ml/min/1.73 cm². NO₂ ^-+NO₃ ^- concentration was measured by Griess reaction. Production of NO was detected by electron paramagnetic resonance spectroscopy. Blood NO was demonstrated to be higher (P<0.001) and serum NO₂ ^-+NO₃ ^- was lower (P=0.003) in patients with type 1 diabetes and no nephropathy vs. healthy subjects. However, serum NO₂ ^-+NO₃ ^- concentration in patients with diabetes and nephropathy did not differ from the levels observed in healthy controls. Urine excretion of NO₂ ^-+NO₃ ^- was significantly decreased in patients with nephropathy, compared with patients without diabetic kidney disease (P=0.006) and healthy subjects (P=0.010). A significant positive correlation was observed between urine NO₂ ^-+NO₃ ^- and estimated glomerular filtration rate in patients with type 1 diabetes (P=0.002) and healthy subjects (P=0.008). Estimated glomerular filtration rate, albuminuria and diabetic nephropathy status were significant predictors of the whole blood NO and NO₂ ^-+NO₃ ^- in serum and urine in patients with type 1 diabetes, as identified by linear regression models. The present study concludes that NO metabolism is impaired by type 1 diabetes and diabetic nephropathy.

Huayu Tongmai Granules protects against vascular endothelial dysfunction via up-regulating miR-185 and down-regulating RAGE

Objective: Receptor of advanced glycation end products (RAGE) is a membrane protein that contributes to the initiation and progression of diabetic vascular complications, which is reported as a target of miR-185. Huayu Tongmai Granules is a Chinese herbal compound that is capable of treating diabetic angiopathy. The present study was designed to explore the molecular biological mechanism by which Huayu Tongmai Granules protects against diabetic angiopathy.Methods: The rat model of diabetes and hyperglucose cell model were established. The blood glucose was detected to verify whether the model was successfully established. Besides, serum nitric oxide (NO) and reactive oxygen species (ROS) concentrations of the rats in each group were determined. The quantitative real-time PCR analysis was performed to examine the mRNA expression levels of miR-185 and other miRNAs in femoral artery of rats or human umbilical vein endothelial cell line. Additionally, the protein levels of RAGE or Bax were determined using Western blotting. Cell apoptosis was determined by terminal dUTP nick-end labeling assay or flow cytometry.Results: In the present study, we found that Huayu Tongmai Granules significantly decreased blood glucose and serum ROS and up-regulated serum NO concentration. MiR-185 was low-expressed in diabetic rats; however, Huayu Tongmai Granules intervention up-regulated miR-185. Stable overexpression of miR-185 directly suppressed the expression of RAGE and further suppressed endothelial cell apoptosis.Conclusion: Huayu Tongmai Granules appears to have a therapeutic effect on diabetic angiopathy that is most probably mediated by miR-185/RAGE axis.

Modifications of expression of genes and proteins involved in DNA repair and nitric oxide metabolism by carbatonides [disodium-2,6-dimethyl-1,4-dihydropyridine- 3,5-bis(carbonyloxyacetate) derivatives] in intact and diabetic rats

Studies on the pathogenesis of diabetes mellitus complications indicate that the compounds reducing free radicals and enhancing DNA repair could be prospective as possible remedies. Carbatonides, the disodium-2,6-dimethyl-1,4- dihydropyridine-3,5-bis(carbonyloxyacetate) derivatives, were tested for these properties. EPR spectroscopy showed that metcarbatone was an effective scavenger of hydroxyl radicals produced in the Fenton reaction, etcarbatone, and propcarbatone were less effective, styrylcarbatone was ineffective. UV/VIS spectroscopy revealed that styrylcarbatone manifested a hyperchromic effect when interacting with DNA, while all other carbatonides showeda hypochromic effect. Rats with streptozotocin induced type 1 DM were treated with metcarbatone, etcarbatone or styrylcarbatone (all compounds at doses 0.05 mg kg-1 or 0.5 mg kg-1) nine days after the DM approval. Gene expression levels in kidneys and blood were evaluated by quantitative RT-PCR; protein expression - immunohistochemically in kidneys, heart, sciatic nerve, and eyes; DNA breakage - by comet assay in nucleated blood cells. Induction of DM induced DNA breaks; metcarbatone and styrylcarbatone (low dose) alleviated this effect. Metcarbatone and etcarbatone up-regulated mRNA and protein of eNOS in kidneys of diabetic animals; etcarbatone also in myocardium. Etcarbatone reduced the expression of increased iNOS protein in myocardium, nerve, and kidneys. iNos gene expression was up-regulated in kidneys by etcarbatone and metcarbatone in diabetic animals. In blood, development of DM increased iNos gene expression; etcarbatone and metcarbatone normalised it. Etcarbatone up-regulated the expression of H2AX in kidneys of diabetic animals but decreased the production of c-PARP1. Taken together, our data indicate that carbatonides might have a potential as drugs intended to treat DM complications.

Study of interaction of antimutagenic 1,4-dihydropyridine AV-153-Na with DNA-damaging molecules and its impact on DNA repair activity

Background

1,4-dihydropyridines (1,4-DHP) possesses important biochemical and pharmacological properties, including antioxidant and antimutagenic activities. It was shown that the antimutagenic 1,4-dihydropyridine AV-153-Na interacts with DNA. The aim of the current study was to test the capability of the compound to scavenge peroxynitrite and hydroxyl radical, to test intracellular distribution of the compound, and to assess the ability of the compound to modify the activity of DNA repair enzymes and to protect the DNA in living cells against peroxynitrite-induced damage.

Methods

Peroxynitrite decomposition was assayed by UV spectroscopy, hydroxyl radical scavenging—by EPR spectroscopy. DNA breakage was determined by the “comet method”, activity of DNA repair enzymes—using Glyco-SPOT and ExSy-SPOT assays. Intracellular distribution of the compound was studied by laser confocal scanning fluorescence microscopy. Fluorescence spectroscopy titration and circular dichroism spectroscopy were used to study interactions of the compound with human serum albumin.

Results

Some ability to scavenge hydroxyl radical by AV-153-Na was detected by the EPR method, but it turned out to be incapable of reacting chemically with peroxynitrite. However, AV-153-Na effectively decreased DNA damage produced by peroxynitrite in cultured HeLa cells. The Glyco-SPOT test essentially revealed an inhibition by AV-153-Na of the enzymes involved thymine glycol repair. Results with ExSy-SPOT chip indicate that AV-153-Na significantly stimulates excision/synthesis repair of 8-oxoguanine (8-oxoG), abasic sites (AP sites) and alkylated bases. Laser confocal scanning fluorescence microscopy demonstrated that within the cells AV-153-Na was found mostly in the cytoplasm; however, a stain in nucleolus was also detected. Binding to cytoplasmic structures might occur due to high affinity of the compound to proteins revealed by spectroscopical methods.

Discussion

Activation of DNA repair enzymes after binding to DNA appears to be the basis for the antimutagenic effects of AV-153-Na.

Effects of an Antimutagenic 1,4-Dihydropyridine AV-153 on Expression of Nitric Oxide Synthases and DNA Repair-related Enzymes and Genes in Kidneys of Rats with a Streptozotocin Model of Diabetes Mellitus

Development of complications of diabetes mellitus (DM), including diabetic nephropathy, is a complex multi-stage process, dependent on many factors including the modification of nitric oxide (NO) production and an impaired DNA repair. The goal of this work was to study in vivo effects of 1,4-dihydropyridine AV-153, known as antimutagen and DNA binder, on the expression of several genes and proteins involved in NO metabolism and DNA repair in the kidneys of rats with a streptozotocin (STZ)-induced model of DM. Transcription intensity was monitored by means of real-time RT-PCR and the expression of proteins by immunohistochemistry. Development of DM significantly induced PARP1 protein expression, while AV-153 (0.5 mg/kg) administration decreased it. AV-153 increased the expression of Parp1 gene in the kidneys of both intact and diabetic animals. Expression of H2afx mRNA and γH2AX histone protein, a marker of DNA breakage, was not changed in diabetic animals, but AV-153 up-regulated the expression of the gene without any impact on the protein expression. Development of DM was followed by a significant increase in iNOS enzyme expression, while AV-153 down-regulated the enzyme expression up to normal levels. iNos gene expression was also found to be increased in diabetic animals, but unlike the protein, the expression of mRNA was found to be enhanced by AV-153 administration. Expression of both eNOS protein and eNos gene in the kidneys was down-regulated, and the administration of AV-153 normalized the expression level. The effects of the compound in the kidneys of diabetic animals appear to be beneficial, as a trend for the normalization of expression of NO synthases is observed.