DNA-binding studies of AV-153, an antimutagenic and DNA repair-stimulating derivative of 1,4-dihydropiridine

In Vitro Genotoxic and Antigenotoxic Effects of Ten Novel Synthesized 4-Thiazolidinone Derivatives

Heterocyclic compounds are found in a variety of drug molecules, and bioactive natural products. 4-Thiazolidinones (4-TZDs), which represent an important class of heterocyclic compounds, are of great interest today with their diverse bioactivities. In this study, ten novel 4-TZD derivatives (C1-C10) were synthesized, characterized by spectroscopic techniques, and their genotoxic, and antigenotoxic properties were investigated in vitro using the Ames Salmonella/microsome mutagenicity assay in the concentration range of 0.2-1.0 mM/plate. The results revealed that none of the compounds were mutagenic on the three different Salmonella typhimurium strains up to the highest concentration tested. Furthermore, in our study, C1, C4, C6, and C9 showed significant, ranging from moderate to strong, antigenotoxic effects against mutagen-induced DNA damage at relatively higher doses. Among these, C4 had the best potential to inhibit the number of revertant colonies induced by 9-aminoacridine (9-AA), with a maximum inhibition rate of 47.9 % for 1.0 mM/plate. As a result, preliminary knowledge about the safety of the use of ten novel synthesized 4-TZD compounds likely to exhibit many bioactivities was obtained in this study. In addition, the significant in vitro antimutagenic activity of some derivatives increases the importance of studies for the development of new pharmacological agents for cancer prevention.

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.

Deletion of SIRT6 in vascular smooth muscle cells facilitates vascular calcification via suppression of DNA damage repair

Vascular calcification is an important risk factor for cardiovascular events, accompanied by DNA damage during the process. The sirtuin 6 (SIRT6) has been reported to alleviate atherosclerosis, which is related to the reduction of DNA damage. However, whether smooth muscle cell SIRT6 mediates vascular calcification involving DNA damage remains unclear. Western blot and immunofluorescence revealed that SIRT6 expression was decreased in human vascular smooth muscle cells (HVSMCs), human and mouse arteries during vascular calcification. Alizarin red staining and calcium content assay showed that knockdown or deletion of SIRT6 significantly promoted HVSMC calcification induced by high phosphorus and calcium, accompanied by upregulation of osteogenic differentiation markers including Runx2 and BMP2. By contrast, adenovirus-mediated SIRT6 overexpression attenuated osteogenic differentiation and calcification of HVSMCs. Moreover, ex vivo study revealed that SIRT6 overexpression inhibited calcification of mouse and human arterial rings. Of note, smooth muscle cell-specific knockout of SIRT6 markedly aggravated Vitamin D₃-induced aortic calcification in mice. Mechanistically, overexpression of SIRT6 reduced DNA damage and upregulated p-ATM during HVSMCs calcification, whereas knockdown of SIRT6 showed the opposite effects. Knockdown of ATM in HVSMCs abrogated the inhibitory effect of SIRT6 overexpression on calcification and DNA damage. This study for the first time demonstrates that vascular smooth muscle cell-specific deletion of SIRT6 facilitates vascular calcification via suppression of DNA damage repair. Therefore, modulation of SIRT6 and DNA damage repair may represent a therapeutic strategy for vascular calcification.

Arene Ru(II) Complexes Acted as Potential KRAS G-Quadruplex DNA Stabilizer Induced DNA Damage Mediated Apoptosis to Inhibit Breast Cancer Progress

A series of arene Ru(II) complexes, [(η⁶-MeC₆H₅)Ru(L)Cl]Cl, (L=o-ClPIP, 1; m-ClPIP, 2 and p-ClPIP, 3) (o-ClPIP=2-(2-chlorophenyl)imidazo[4,5-f][1,10]phenanthroline; m-ClPIP=2-(3-chlorophenyl)imidazo[4,5-f][1,10]phenanthroline; p-ClPIP=2-(4-chlorophenyl)imidazo[4,5-f][1,10]phenanthroline) was synthesized and investigated as a potential apoptosis inducer in chemotherapy. Spectroscopy and molecular docking simulations show that 1 exhibits moderated binding affinity to KRAS G-quadruplex DNA by groove mode. Further, in vitro studies reveal that 1 displays inhibitory activity against MCF-7 growth with IC₅₀ = 3.7 ± 0.2 μM. Flow cytometric analysis, comet assay, and immunofluorescence confirm that 1 can induce the apoptosis of MCF-7 cells and G0/G1 phase arrest through DNA damage. In summary, the prepared arene Ru(II) complexes can be developed as a promising candidate for targeting G-quadruplex structure to induce the apoptosis of breast cancer cells via binding and stabilizing KRAS G-quadruplex conformation on oncogene promoter.

1,2,3-Triazoles of 8-Hydroxyquinoline and HBT: Synthesis and Studies (DNA Binding, Antimicrobial, Molecular Docking, ADME, and DFT)

A new series of 1,2,3-triazole hybrids containing either 2- or 4-hydroxyphenyl benzothiazole (2- or 4-HBT) and naphthalen-1-ol or 8-hydroxyquinoline (8-HQ) was synthesized in high yields and fully characterized. In vitro DNA binding studies with herring fish sperm DNA (hs-DNA) showed that quinoline- and 2-HBT-linked 1,2,3-triazoles of shorter alkyl linkers such as 6a are better with a high binding affinity (3.90 × 105 L mol-1) with hs-DNA as compared to naphthol- and 4-HBT-linked 1,2,3-triazoles bound to longer alkyl linkers. Molecular docking of most active 1,2,3-triazoles 6a-f showed high binding energy of 6a (-8.7 kcal mol-1). Also, compound 6a displayed considerable antibacterial activity and superior antifungal activity with reference to ciprofloxacin and fluconazole, respectively. The docking results of the fungal enzyme lanosterol 14-α-demethylase showed high binding energy for 6a (-9.7 kcal mol-1) involving dominating H-bonds, electrostatic interaction, and hydrophobic interaction. The absorption, distribution, metabolism, and excretion (ADME) parameter, Molinspiration bioactivity score, and the PreADMET properties revealed that most of the synthesized 1,2,3-triazole molecules possess desirable physicochemical properties for drug-likeness and may be considered as orally active potential drugs. The electrophilicity index and chemical hardness properties were also studied by density functional theory (DFT) using the B3LYP/6-311G(d,p) level/basis set.

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.

Antioxidant, antibacterial, and antimutagenic activity of Piper nigrum seeds extracts

Piper nigrum is a widely used plant in traditional remedies and known for its numerous biological properties. However, fraction-based antioxidant activity and their antimutagenic potential are not yet fully investigated. Different extracts of the seeds P. nigrum were obtained by sequential extraction in different solvents. All extracts were evaluated for antibacterial and antioxidant activities using different methods. The most active fraction was analyzed for antimutagenic activity using the Ames Salmonella test. The antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) was found to be more prominent compared to ESβL producing Klebsiella pneumoniae isolates. The MIC values were found to be lower against MRSA than K. pneumoniae. The extract showing highest antioxidant activity (methanol extract) was further tested for antimutagenic activity both against direct and indirect-acting mutagens. A varying level of antimutagenic activity was shown by methanol extract at highest tested concentration (200 µg/plate). Alkaloids, phenols, and flavonoids were detected as major class of compounds in methanol extract. Gas chromatography-mass spectrometry (GC–MS) analysis showed the presence of various phytocompounds. Based on molecular docking of two major active phytocompounds (piperine and copaene), they were found to interact at the minor groove of DNA. Molecular dynamics (MD) simulation revealed that both the ligands were quite stable with DNA under physiological conditions. The ability of phytocompounds to interact with DNA might be reducing the interaction of mutagens and could be one of the possible mechanism of anti-mutagenic activity of P. nigrum extract. This study highlights the antioxidant and antimutagenic potential of Piper nigrum. The role of phytocompounds present in the bioactive extract is needed to be explored further for herbal drug research.

Novel indole-thiazole and indole-thiazolidinone derivatives as DNA groove binders

In this study, we report the synthesis of eight novel indole-thiazole and indole-thiazolidinone derivatives, as well as their ability to interact with DNA, analysed through the UV-vis absorption, fluorescence, circular dichroism (CD), viscosity techniques and molecular docking. The ctDNA interaction analysis demonstrated different spectroscopic effects and the affinity constants (Kb) calculated by the UV-vis absorption method were between 2.08 × 10⁵ and 6.99 × 10⁶ M^-1, whereas in the fluorescence suppression constants (Ksv) ranged between 0.38 and 0.77 × 10⁴ M^-1 and 0.60-7.59 × 10⁴ M^-1 using Ethidium Bromide (EB) and 4',6-Diamidino-2-phenylindole (DAPI) as fluorescent probes, respectively. Most derivatives did not alter significantly the secondary structure of the ctDNA according to the CD results. None of the compounds was able to change the relative viscosity of the ctDNA. These results prove that compounds interact with ctDNA via groove binding, which was confirmed by A-T rich oligonucleotide sequence assay with compound JF-252, suggesting the importance of both the phenyl ring coupled to C-4 thiazole ring and the bromo-unsubstituted indole nucleus.

Spectroscopic and electrochemical study of interactions between DNA and different salts of 1,4-dihydropyridine AV-153

1,4-dihydropyridines (1,4-DHP) possess important biochemical and pharmacological properties, including antimutagenic and DNA-binding activity. The latter activity was first described for water-soluble 1,4-DHP with carboxylic group in position 4, the sodium salt of the 1,4-DHP derivative AV-153 among others. Some data show the modification of physicochemical properties and biological activities of organic compounds by metal ions that form the salts. We demonstrated the different affinity to DNA and DNA-protecting capacity of AV-153 salts, depending on the salt-forming ion (Na, K, Li, Rb, Ca, Mg). This study aimed to use different approaches to collate data on the DNA-binding mode of AV-153-Na and five other AV-153 salts. All the AV-153 salts in this study quenched the ethidium bromide and DNA complex fluorescence, which points to an intercalation binding mode. For some of them, the intercalation binding was confirmed using cyclic voltammetry and circular dichroism spectroscopy. It was shown that in vitro all AV-153 salts can interact with four DNA bases. The FTIR spectroscopy data showed the interaction of AV-153 salts with both DNA bases and phosphate groups. A preference for base interaction was observed as the AV-153 salts interacted mostly with G and C bases. However, the highest differences were detected in the spectral region assigned to phosphate groups, which might indicate either conformational changes of DNA molecule (B form to A or H form) or partial denaturation of the molecule. According to the UV/VIS spectroscopy data, the salts also interact with the human telomere repeat, both in guanine quadruplex (G4) and single-stranded form; Na and K salts manifested higher affinity to G4, Li and Rb -to single-stranded DNA.

Metal ions modify DNA-protecting and mutagen-scavenging capacities of the AV-153 1,4-dihydropyridine

1,4-Dihydropyridines (1,4-DHP) possess important biochemical and pharmacological properties, including antioxidant and antimutagenic activities. AV-153-Na, an antimutagenic and DNA-repair enhancing compound was shown to interact with DNA by intercalation. Here we studied DNA binding of several AV-153 salts to evaluate the impact of AV-153 modifications on its DNA binding capacity, the ability to scavenge the peroxynitrite, to protect HeLa and B-cells cells against DNA damage. Affinity of the AV-153 salts to DNA measured by a fluorescence assay was dependent on the metal ion forming a salt in position 4 of the 1,4-DHP, and it decreased as follows: Mg > Na > Ca > Li > Rb > K. AV-153-K and AV-153-Rb could not react chemically with peroxynitrite as opposed to AV-153-Mg and AV-153-Ca, the latter increased the decomposition rate of peroxynitrite. AV-153-Na and AV-153-Ca effectively reduced DNA damage induced by peroxynitrite in HeLa cells, while AV-153-K and AV-153-Rb were less effective, AV-153-Li did not protect the DNA, and AV-153-Mg even caused DNA damage itself. The Na, K, Ca and Mg AV-153 salts were also shown to reduce the level of DNA damage in human B-cells from healthy donors. Thus, metal ions modify both DNA-binding and DNA-protecting effects of the AV-153 salts.

Antioxidative 1,4-Dihydropyridine Derivatives Modulate Oxidative Stress and Growth of Human Osteoblast-Like Cells In Vitro

Oxidative stress has been implicated in pathophysiology of different human stress- and age-associated disorders, including osteoporosis for which antioxidants could be considered as therapeutic remedies as was suggested recently. The 1,4-dihydropyridine (DHP) derivatives are known for their pleiotropic activity, with some also acting as antioxidants. To find compounds with potential antioxidative activity, a group of 27 structurally diverse DHPs, as well as one pyridine compound, were studied. A group of 11 DHPs with 10-fold higher antioxidative potential than of uric acid, were further tested in cell model of human osteoblast-like cells. Short-term combined effects of DHPs and 50 µM H₂O₂ (1-h each), revealed better antioxidative potential of DHPs if administered before a stressor. Indirect 24-h effect of DHPs was evaluated in cells further exposed to mild oxidative stress conditions induced either by H₂O₂ or tert-butyl hydroperoxide (both 50 µM). Cell growth (viability and proliferation), generation of ROS and intracellular glutathione concentration were evaluated. The promotion of cell growth was highly dependent on the concentrations of DHPs used, type of stressor applied and treatment set-up. Thiocarbatone III-1, E2-134-1 III-4, Carbatone II-1, AV-153 IV-1, and Diethone I could be considered as therapeutic agents for osteoporosis although further research is needed to elucidate their bioactivity mechanisms, in particular in respect to signaling pathways involving 4-hydroxynoneal and related second messengers of free radicals.

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.

Genotoxicity inhibition by Syzygium cumini (L.) seed fraction and rutin: understanding the underlying mechanism of DNA protection

Considering the ethnopharmacological importance of Syzygium cumini's seed and the lack of information on the antimutagenic and DNA-protecting mechanisms, a fraction-based study was conducted. Four different (hexane, chloroform, ethyl acetate, and aqueous) fractions were obtained from the sequential extraction of the methanolic extract of the seed. The most active antioxidant fraction (ethyl acetate) contained significant amount of phenolics and flavonoids. LC-qTOF-MS analysis of the ethyl acetate fraction revealed the presence of rutin, myricetin, naringin, cuscohygrin, and epoxycarryophyllone as constituent phytocompounds. The ethyl acetate fraction (100 μg ml-1) and a selected compound (rutin, 40 μg ml-1) showed remarkable decrease in the revertants frequency range from 74-77% and 66-84%, respectively, against both the mutagens (sodium azide (NaN3) and methyl methane sulfonate (MMS)) in the Salmonella typhimurium tester strains. All the statistical analyses were at a significance level of 0.05 between the different treatment groups. Moreover, the underlying mechanism of antimutagenicity using different treatment regime for rutin was explored. MMS-mediated DNA fragmentation and oxidation in lymphocytes were also shown to be decreased significantly when treated with the ethyl acetate fraction and rutin. Oxidative damage to pBR322 plasmid DNA was also reduced when incubated with different concentration of the ethyl acetate fraction and rutin. Biophysical (UV, fluorescence, ITC, etc.) and computational methods were employed to obtain a closer look at the DNA-rutin interaction. The data obtained clearly revealed that the ethyl acetate fraction exhibited promising antimutagenic and DNA-protective activity and its flavonoid constituents, including rutin, contribute significantly to the observed activity.

Antioxidant properties and anti-mutagenic potential of Piper Cubeba fruit extract and molecular docking of certain bioactive compounds

Spices and herbs are recognized as sources of natural antioxidants and thus play an important role in the chemoprevention of diseases and aging. Piper cubeba is one among them and known for its medicinal properties for decades. Various biological activities are associated with its extract and phytocompounds. However, the anti-mutagenic activity of antioxidant rich extract is less explored. In this study, we performed the fraction-based antioxidant activity of P. cubeba using four different assays and evaluated the anti-mutagenic activity of most potent antioxidant fraction using Salmonella typhimurium tester strains against four mutagens (methyl methanesulfonate [MMS], sodium azide [SA], benzo(a)pyrene, and 2-aminoflourene) respectively. Among all tested fractions at 25-200 µg/ml, ethanolic extract revealed highest antioxidant activity and significant anti-mutagenicity against both direct and indirect acting mutagens at least one tester strain. Phytochemical analysis by gas chromatography-mass spectrometry (GC/MS) revealed the presence of various phytocompounds including copaene, isocaryophyllene, α-cubebene, etc. Molecular docking studies on DNA binding interactions of GC/MS detected phytocompounds highlight the possible mode of binding. In summary, these in vitro studies have provided the scientific basis for validation of using this plant in the traditional system of medicine and highlighted the need for exploring the role of various compounds for therapeutic efficacy. On the other hand, synergistic interaction among phytocompounds is to be explored to optimize or standardize the extracts for the exploitation in modern phytomedicine.

In vitro interaction of cefotaxime with calf thymus DNA: Insights from spectroscopic, calorimetric and molecular modelling studies

Cefotaxime is third generation antibiotic with known therapeutic efficacy against bacterial infections including cerebral abscesses and bacterial meningitis. The β-lactam group of drugs are considered safest antibiotics. Many antibiotics directly interact with DNA and alter their expression profile. Thus, it is necessary to understand the binding mode and its relevance to drug activity and toxicity. There is considerably a remarkable focus on deciphering the binding mechanism of these therapeutic agents as DNA is one of the major target for wide range of drugs. Cefotaxime has been extensively studied for its pharmacological properties while its binding mode to DNA has not been explicated so far. In this study, we have unveiled the binding mechanism of cefotaxime to DNA by using various biophysical, thermodynamic and in silico techniques. UV-vis spectroscopy confirmed the formation cefotaxime-DNA complex along with a brief idea about the extent of interaction. Fluorescence spectroscopy yielded the values of various binding constants and explained mode of fluorescence quenching to be static. CD spectroscopy, thermal denaturation, KI quenching and viscosity measurement explained that cefotaxime is groove binder. Measuring the effect of ions on cefotaxime-DNA complex ensured that it does not bind to DNA electrostatically. Dye displacement experiments finally confirmed that cefotaxime binds to the minor groove of DNA. ITC gave the thermodynamic profile of this binding in which negative value of Gibb's free energy change revealed that the process is spontaneous. Molecular modelling finally strengthened our experimental results that cefotaxime was located in curved contour of minor groove of DNA. The findings support on safety of drug and may have a little interference on normal biological functions.

Microwave-Assisted Synthesis of Imidazo[4,5-f][1,10]phenanthroline Derivatives as Apoptosis Inducers in Chemotherapy by Stabilizing Bcl-2 G-quadruplex DNA

Herein, a series of imidazo[4,5-f][1,10] phenanthroline derivatives RPIP (PIP = imidazo [4,5-f][1,10] phenanthroline, R = NO₂, 1; CF₃, 2; Cl, 3; OH, 4) have been synthesized in yields of 82.3–94.7% at 100 °C under the irradiation of microwave. MTT assay has been utilized to evaluate the inhibitory activity (IC₅₀) of these compounds against the growth of various tumor cells, and the results revealed that these compounds, especially 1, exhibited excellent inhibitory activity against the growth of A549 cells with IC₅₀ of 15.03 μM. Moreover, it’s also confirmed that 1 can penetrate into the membrane of tumor cells and distribute in mitochondria when observed under microscopy, resulting apoptosis of tumor cells. The further studies showed that 1 can bind to bcl-2 G-quadruplex DNA, which demonstrated by the increase of melting point of bcl-2 G4 DNA in the presence of 1, as well as electronic titration and emission spectra. In a word, this kind of compound may develop as a potential apoptosis inducer in cancer chemotherapy via binding and stabilizing to the bcl-2 G-quadruplex DNA.

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.

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

Diabetes mellitus (DM) and its complications cause numerous health and social problems throughout the world. Pathogenic actions of nitric oxide (NO) are responsible to a large extent for development of complications of DM. Search for compounds regulating NO production in patients with DM is thus important for the development of pharmacological drugs. Dihydropyridines (1,4-DHPs) are prospective compounds from this point of view. The goals of this study were to study the in vivo effects of new DHPs on NO and reactive nitrogen and oxygen species production in a streptozotocin (STZ)-induced model of DM in rats and to study their ability to protect DNA against nocive action of peroxynitrite. STZ-induced diabetes caused an increase in NO production in the liver, kidneys, blood and muscles, but a decrease in NO in adipose tissue of STZ-treated animals. Cerebrocrast treatment was followed by normalization of NO production in the liver, kidneys and blood. Two other DHPs, etaftorone and fenoftorone, were effective in decreasing NO production in kidneys, blood and muscles of diabetic animals. Furthermore, inhibitors of nitric oxide synthase (NOS) and an inhibitor of xanthine oxidoreductase (XOR) decreased NO production in kidneys of diabetic animals. Treatment with etaftorone decreased expression of inducible NOS and XOR in kidneys, whereas it increased the expression of endothelial NOS. In vitro, the studied DHPs did not significantly inhibit the activities of NOS and XOR but affected the reactivity of peroxynitrite with DNA. These new DHPs thus appear of strong interest for treatment of DM complications.