Efficient Cleavage of pUC19 DNA by Tetraaminonaphthols

In an attempt to create models of phosphodiesterases, we previously investigated bis(guanidinium) naphthols. Such metal-free anion receptors cleaved aryl phosphates and also plasmid DNA. Observed reaction rates, however, could not compete with those of highly reactive metal complexes. In the present study, we have replaced the guanidines by ethylene diamine side chains which accelerates the plasmid cleavage by compound 13 significantly (1 mM 13: t1/2=22 h). Further gains in reactivity are achieved by azo coupling of the naphthol unit. The electron accepting azo group decreases the pKa of the hydroxy group. It can also serve as a dye label and a handle for attaching DNA binding moieties. The resulting azo naphthol 17 not only nicks (1 mM 17: t1/2~1 h) but also linearizes pUC19 DNA. Although the high reactivity of 17 seems to result in part from aggregation, in the presence of EDTA azo naphthol 17 obeys first order kinetics (1 mM 17: t1/2=4.8 h), reacts four times faster than naphthol 13 and surpasses by far the former bis(guanidinium) naphthols 4 and 5.

Synthesis of Quinoline-2-Carboxylic Acid Aryl Ester and Its Apoptotic Action on PC3 Prostate Cancer Cell Line

The aim of the present study is to synthesise an aryl ester compound from quinoline-2-carboxylic acid to evaluate its apoptotic, cell cycle blockade, and antiproliferative activity on the prostate cancer cell lines (PC3). Chromatographic and spectroscopic analysis was used to identify the synthesised carboxylic acid compound. The synthesised compound was treated with a PC3 cell line for 24 h with control. The cells were treated at various concentration ranges of 0, 3.91, 7.81, 15.63, 31.25, 62.5, 125, 250, 500, and 1000 µg/mL each. The cytotoxicity effect was studied by MTT assay, and their anticancer activity was further evaluated using cell cycle analysis, DNA fragmentation assay, acridine orange-ethidium bromide staining, and Western blot analysis. The end antiproliferative result showed that PC3 cell viability decreases in a concentration-dependent manner and the synthesised compound exhibited potent cytotoxicity against PC3 cells with an IC50 value of 26 µg/mL at the concentration of 125 µg. The increase in the number of apoptotic cells was observed after treating PC3 cells with the sample in double-staining methods. S phase of the cell cycle was significantly blocked by the test sample, and a typical ladder pattern of internucleosomal fragmentation was observed. A decrease in the live cells was observed with the sample in AO/ET-BR. A significant increase in the Bax expression and a decrease in Bcl-2 expression observed enhance the activity of caspases-7 and -9. The synthesised compound had shown to possess excellent cytotoxic effect through inducing apoptosis, especially causing cell cycle arrest at the S phase.

Developing an Anticancer Copper(II) Multitarget Pro-Drug Based on the His146 Residue in the IB Subdomain of Modified Human Serum Albumin

Designing a multitarget anticancer drug with improved delivery and therapeutic efficiency in vivo presents a great challenge. Thus, we proposed to design an anticancer multitarget metal pro-drug derived from thiosemicarbazone based on the His146 residue in the IB subdomain of palmitic acid (PA)-modified human serum albumin (HSA-PA). The structure-activity relationship of six Cu(II) compounds with 6-methyl-2-formylpyridine-⁴N-substituted thiosemicarbazones were investigated, and then the multitarget capability of 4b was confirmed in cancer cell DNA and proteins. The structure of the HSA-PA-4b complex (HSA-PA-4b) revealed that 4b is bound to the IB subdomain of modified HSA, and that His146 replaces the nitrate ligand in 4b, coordinating with Cu²⁺, whereas PA is complexed with the IIA subdomain by its carboxyl forming hydrogen bonds with Lys199 and His242. In vivo data showed that 4b and the HSA-PA-4b complex inhibit lung tumor growth, and the targeting ability and therapeutic efficacy of the PA-modified HSA complex was stronger than 4b alone.

Phosphodiester models for cleavage of nucleic acids

Nucleic acids that store and transfer biological information are polymeric diesters of phosphoric acid. Cleavage of the phosphodiester linkages by protein enzymes, nucleases, is one of the underlying biological processes. The remarkable catalytic efficiency of nucleases, together with the ability of ribonucleic acids to serve sometimes as nucleases, has made the cleavage of phosphodiesters a subject of intensive mechanistic studies. In addition to studies of nucleases by pH-rate dependency, X-ray crystallography, amino acid/nucleotide substitution and computational approaches, experimental and theoretical studies with small molecular model compounds still play a role. With small molecules, the importance of various elementary processes, such as proton transfer and metal ion binding, for stabilization of transition states may be elucidated and systematic variation of the basicity of the entering or departing nucleophile enables determination of the position of the transition state on the reaction coordinate. Such data is important on analyzing enzyme mechanisms based on synergistic participation of several catalytic entities. Many nucleases are metalloenzymes and small molecular models offer an excellent tool to construct models for their catalytic centers. The present review tends to be an up to date summary of what has been achieved by mechanistic studies with small molecular phosphodiesters.

Synthesis, DNA binding profile and DNA cleavage pathway of divalent metal complexes

Divalent metal complexes of dipyridylamine ligand with an anthracene moiety induced considerable oxidative DNA cleavage in the presence hydrogen peroxide and dioxygen.

Synthesis, hydrolytic DNA-cleaving activities and cytotoxicities of EDTA analogue-tethered pyrrole-polyamide dimer-based Ce(IV) complexes

Two EDTA analogue-tethered C2-symmetrical dimeric monopyrrole-polyamide 5 and dipyrrole-polyamide 6, and their corresponding Ce(IV) complexes Ce-5 and Ce-6 were synthesized and fully characterized. Agarose gel electrophoresis studies on pBR322 DNA cleavage indicate that complexes Ce-5 and Ce-6 exhibited potent DNA-cleaving activities under physiological conditions. The maximal first-order rate constants (kmax's) were (0.42 ± 0.02) h(-1) for Ce-5 and (0.52 ± 0.02) h(-1) for Ce-6, respectively, suggesting that both complexes catalyzed the cleavage of supercoiled DNA by up to approximately 10(8)-fold. Complex Ce-6 exhibited ca 10-fold higher overall catalytic activity (kmax/KM) than Ce-5, which may be ascribed to its higher DNA-binding affinity. Inhibition experiments and a model study convincingly suggest that both complexes Ce-5 and Ce-6 functioned as hydrolytic DNA-cleavers. In addition, both complexes were found to display moderate inhibitory activity toward A549 and HepG-2 cells.

Recent advances in small organic molecules as DNA intercalating agents: synthesis, activity, and modeling

The interaction of small molecules with DNA plays an essential role in many biological processes. As DNA is often the target for majority of anticancer and antibiotic drugs, study about the interaction of drug and DNA has a key role in pharmacology. Moreover, understanding the interactions of small molecules with DNA is of prime significance in the rational design of more powerful and selective anticancer agents. Two of the most important and promising targets in cancer chemotherapy include DNA alkylating agents and DNA intercalators. For these last the DNA recognition is a critical step in their anti-tumor action and the intercalation is not only one kind of the interactions in DNA recognition but also a pivotal step of several clinically used anti-tumor drugs such as anthracyclines, acridines and anthraquinones. To push clinical cancer therapy, the discovery of new DNA intercalators has been considered a practical approach and a number of intercalators have been recently reported. The intercalative binding properties of such molecules can also be harnessed as diagnostic probes for DNA structure in addition to DNA-directed therapeutics. Moreover, the problem of intercalation site formation in the undistorted B-DNA of different length and sequence is matter of tremendous importance in molecular modeling studies and, nowadays, three models of DNA intercalation targets have been proposed that account for the binding features of intercalators. Finally, despite DNA being an important target for several drugs, most of the docking programs are validated only for proteins and their ligands. Therefore, a default protocol to identify DNA binding modes which uses a modified canonical DNA as receptor is needed.

Density functional studies on (NCH)n azagraphane: activated surface for organocatalysis

The reactive surface of azagraphane formed by alternate nitrogen substitution on graphane contains the basic nitrogen as well as the activated C–H with hydridic nature owing to the anomeric effect.