Interaction of two peptide-acridine conjugates containing the SPKK peptide motif with DNA and chromatin

Experiments and Calculation on New N,N-bis-Tetrahydroacridines

Tetrahydroacridines arouse particular interest due to the potential possibilities of application in the medical field and protection against corrosion. Bis-tetrahydroacridines were newly synthesized by Pfitzinger condensation of 5,5'-(ethane-1,2-diyl) diindoline-2,3-dione with several cyclanones. NMR, MS, and FT-IR were used to prove their molecular structure. In addition, a computer-aided study was performed for the lowest energy conformers of each structure, in vacuum conditions, at ground state using DFT models to assess their electronic properties. UV-Vis and voltammetric methods (cyclic voltammetry, differential pulse voltammetry, and rotating disk electrode voltammetry) were used to investigate their optical and electrochemical properties. The results obtained for these π-conjugated heteroaromatic compounds lead to the conclusion that they have real potential in applications in different fields such as pharmaceuticals and especially as corrosion inhibitors.

Peptide Regulation of Gene Expression: A Systematic Review

Peptides are characterized by their wide range of biological activity: they regulate functions of the endocrine, nervous, and immune systems. The mechanism of such action of peptides involves their ability to regulate gene expression and protein synthesis in plants, microorganisms, insects, birds, rodents, primates, and humans. Short peptides, consisting of 2-7 amino acid residues, can penetrate into the nuclei and nucleoli of cells and interact with the nucleosome, the histone proteins, and both single- and double-stranded DNA. DNA-peptide interactions, including sequence recognition in gene promoters, are important for template-directed synthetic reactions, replication, transcription, and reparation. Peptides can regulate the status of DNA methylation, which is an epigenetic mechanism for the activation or repression of genes in both the normal condition, as well as in cases of pathology and senescence. In this context, one can assume that short peptides were evolutionarily among the first signaling molecules that regulated the reactions of template-directed syntheses. This situation enhances the prospects of developing effective and safe immunoregulatory, neuroprotective, antimicrobial, antiviral, and other drugs based on short peptides.

Synthesis of acridinyl-thiazolino derivatives and their evaluation for anti-inflammatory, analgesic and kinase inhibition activities

Variety of N-(4-phenyl-3-(2',3',4'(un)substituted phenyl)thiazol-2(3H)-ylidene)-2,4(un)substituted acridin-9-amine (4a-o) and 1-[(2,4-(un)substituted acridin-9-yl)-3-(4-phenyl-3-(2',3',4'(un)substituted phenyl)thiazol-2(3H)-ylidene)]isothiourea (5a-h) derivatives have been synthesized by condensation of 4-phenyl-3-(2',3',4'(un)substituted phenyl)thiazol-2(3H)-imine (3a-g) with 9-chloro-2,4-(un)substituted acridine (1a-c) and 9-isothiocyanato-2,4-(un)substituted acridine (2a-d), respectively. All these compounds were characterized by correct 1H NMR, FT-IR, MS and elemental analyses. These compounds were screened for anti-inflammatory, analgesic and kinase (CDK1, CDK5 and GSK3) inhibition activities. Some compounds exhibited good anti-inflammatory (25-32%) and potent analgesic (50-75%) activities, at 50 mg/kg p.o. A compound, 4o (R1 = H, R2 = OCH3, R3 = CH3, R4 = CH3, R5 = H) exhibited moderate CDK1 (IC50 = 8.5 microM) inhibition activity.

Oxoazabenzo[de]anthracenes Conjugated to Amino Acids: Synthesis and Evaluation as DNA-Binding Antitumor Agents

We report the synthesis of an original series of oxoazabenzo[de]anthracenes conjugated to an amino acid: Ala, Phe, Pro, Lys, or Gly (4a-e, respectively). The compounds, derived from 1,8-dihydroxyanthracene-9,10-dione, were studied for DNA binding and cytotoxicity. Melting temperature, fluorescence quenching, and surface plasmon resonance methods all indicated that the lysine derivative 4d binds to DNA much more strongly that the Pro, Ala, and Gly conjugates whereas the Phe analogue showed the lowest DNA binding capacity. These compounds form intercalation complexes with DNA, as judged from electric linear dichroism and topoisomerase I-based DNA unwinding experiments. Preferential binding of 4d to defined sequences such as 5'-CTAAAGG and 5'-ATGC was evidenced by DNase I footprinting. This Lys conjugate was found to be over 20 times more cytotoxic to CEM human leukemia cells than the other conjugates, with an IC50 in the submicromolar range. A high antiproliferative activity, likely attributable to the enhanced DNA binding capacity, is maintained despite the incapacity of the compound to stabilize topoisomerase-DNA covalent complexes. The cell cycle effects of 4d consisted in an S phase accumulation of cells coupled with a pro-apoptotic action (appearance of hypodiploid sub-G1 cells) which were confirmed by measuring the inhibition of BrdU incorporation into DNA and labeling of phosphatidylserine residues with annexin V-FITC by means of flow cytometry. Altogether, the work provides interesting structure-activity relationships in the oxoazabenzo[de]anthracene-amino acid conjugate series and identifies the lysine derivative 4d as a promising candidate for further in vivo evaluation and drug design.

Osmium tetroxide, used in the treatment of arthritic joints, is a fast mimic of superoxide dismutase

Aqueous solutions of osmium tetroxide (OsO4) have been injected into arthritic knees for the past 45 years to chemically destroy diseased tissue, in a procedure termed "chemical synovectomy." Arthritis is an inflammatory disease. The primary inflammatory chemical species are the superoxide anion radical (O2.-) and nitric oxide (.NO), which combine to form the peroxynitrite anion (ONOO-). Here we show that OsO4 does not react with ONOO- but very efficiently catalyzes the dismutation of O2.- to O2 and H2O2. Using the pulse-radiolysis technique, the catalytic rate constant has been determined to be (1.43+/-0.04) x 10(9) M-1 s-1, independent of the pH in the 5.1-8.7 range. This value is about half that for the natural Cu,Zn-superoxide dismutase (Cu,Zn-SOD). Per unit mass, OsO4 is about 60 times more active than Cu,Zn-SOD. The catalytically active couple is OsVIII/OsVII, OsVIII oxidizing O2.- to O2 with a bimolecular rate constant of k=(2.6+/-0.1)x10(9) M-1 s-1 and OsVII reducing it to H2O2 with a bimolecular rate constant of (1.0+/-0.1)x10(9) M-1 s-1. Although lower valent osmium species are intrinsically poor catalysts, they are activated through oxidation by O2.- to the catalytic OsVIII/OsVII redox couple. The OsVIII/OsVII catalyst is stable to biochemicals other than proteins and peptides comprising histidine, cysteine, and dithiols.

Sometimes a great motion: the application of transient electric birefringence to the study of macromolecular structure

First described in the late 1800s, the phenomenon of electric birefringence is becoming increasingly useful as a probe of the solution conformations of proteins and nucleic acids. The birefringence response to a transient electric field is a sensitive indicator of the rotational motions (and hence the physical dimensions) of macromolecules in solution. Recent advances, both in instrumentation and in the efficient production of high-quality biopolymers, have dramatically increased the sensitivity and range of applicability of the method.

Electric linear dichroism as a new tool to study sequence preference in drug binding to DNA

An original approach using electric linear dichroism (ELD) and natural DNAs and polynucleotides of differing base composition has been developed with the aim to investigate the sequence-dependent recognition of DNA by drugs. Both intercalators and minor groove binders have been studied as well as certain hybrid molecules. The results indicate that the orientation of drugs upon binding to nucleic acids can change markedly according to the target sequence. Among the intercalators tested, only actinomycin D and hycanthone show a clear preference for GC- and AT-rich sequences, respectively. For minor groove binders, the linear dichroism showing a strong dependence on base composition of the DNA and polynucleotides is most pronounced. Netropsin and distamycin bind to DNA with a marked AT specificity. Hoechst 33258, berenil and DAPI exhibit positive and negative dichroism signals at AT and GC sites respectively, suggesting that at least two types of drug-DNA interaction are involved depending on the AT/GC content of the DNA. Further investigations using polynucleotides with inosine substituted for guanosine, and competition experiments with intercalative drugs suggest that Hoechst 33258, berenil and DAPI interact with GC sequences via a non-classical intercalation process.