New dimeric carbazole-benzimidazole mixed ligands for the stabilization of human telomeric G-quadruplex DNA and as telomerase inhibitors. A remarkable influence of the spacer

for selectively targeting cancer cells. Herein, we report the design and evolution of a new kind of carbazole-based benzimidazole dimers for their efficient telomerase inhibition activity. Spectroscopic titrations reveal the ligands high affinity toward the G4 DNA with significantly higher selectivity over duplex-DNA. The electrophoretic mobility shift assay shows that the ligands efficiently promote the formation of 04 DNA even at a lower concentration of the stabilizing K+ ions. The TRAP-LIG assay demonstrates the ligand's potential telomerase inhibition activity and also establishes that the activity proceeds via G4 DNA stabilization. An efficient nuclear internalization of the ligands in several common cancer cells (HeLa, HT1080, and A549) also enabled differentiation between normal HFF cells in co-cultures of cancer and normal ones. The ligands induce significant apoptotic response and antiproliferative activity toward cancer cells selectively when compared to the normal cells.

Zinc acetylacetonate hydrate adducted with nitrogen donor ligands: Synthesis, spectroscopic characterization, and thermal analysis

We report synthesis, spectroscopic characterization, and thermal analysis of zinc acetylacetonate complex adducted by nitrogen donor ligands, such as pyridine, bipyridine, and phenanthroline. The pyridine adducted complex crystallizes to monoclinic crystal structure, whereas other two adducted complexes have orthorhombic structure. Addition of nitrogen donor ligands enhances the thermal property of these complexes as that with parent metal-organic complex. Zinc acetylacetonate adducted with pyridine shows much higher volatility (106 degrees C), decomposition temperature (202 degrees C) as that with zinc acetylacetonate (136 degrees C, 220 degrees C), and other adducted complexes. All the adducted complexes are thermally stable, highly volatile and are considered to be suitable precursors for metal organic chemical vapor deposition. The formation of these complexes is confirmed by powder X-ray diffraction, Fourier transform infrared spectroscopy, mass spectroscopy, and elemental analysis. The complexes are widely used as starting precursor materials for the synthesis of ZnO nanostructures by microwave irradiation assisted coating process. (c) 2015 Elsevier B.V. All rights reserved.

Cyclic Cationic Peptides Containing Sugar Amino Acids Selectively Distinguishes and Inhibits Maturation of Pre-miRNAs of the Same Family

The discovery of microRNAs (miRNAs) has added a new dimension to the gene regulatory networks, making aberrantly expressed miRNAs as therapeutically important targets. Small molecules that can selectively target and modulate miRNA levels can thus serve as lead structures. Cationic cyclic peptides containing sugar amino acids represent a new class of small molecules that can target miRNA selectively. Upon treatment of these small molecules in breast cancer cell line, we profiled 96 therapeutically important miRNAs associated with cancer and observed that these peptides can selectively target paralogous miRNAs of the same seed family. This selective inhibition is of prime significance in cases when miRNAs of the same family have tissue-specific expression and perform different functions. During these conditions, targeting an entire miRNA family could lead to undesired adverse effects. The selective targeting is attributable to the difference in the three-dimensional structures of precursor miRNAs. Hence, the core structure of these peptides can be used as a scaffold for designing more potent inhibitors of miRNA maturation and hence function.

Photocytotoxic ternary copper(II) complexes of histamine Schiff base and pyridyl ligands

Ternary copper(Il) complexes of salicylaldehyde-histamine Schiff base (HL) and pyridyl ligands, viz. Cu(bpy)(L)](ClO4) (1) and Cu(dppz)(L)](C104) (2), where bpy is 2,2'-bipyridine (in 1) and dppz is dipyrido3,2-a:2',3'-c]phenazine (in 2), were synthesized, characterized and their DNA binding, photo-activated DNA cleavage activity and photocytotoxicity studied. The 1:1 electrolytic one-electron paramagnetic complexes showed a d-d band near 670 nm in aqueous DMF (1:1 v/v). The crystal structure of complex 1 showed the metal in CuN4O distorted square-pyramidal geometry. Complex 2 intercalatively binds to calf-thymus (ct) DNA with a binding constant (K-b) of similar to 10(5) M-1. It exhibited moderate chemical nuclease activity but excellent DNA photocleavage activity in red light of 647 nm forming (OH)-O-center dot radicals. It showed remarkable photocytotoxicity in human cervical cancer cells (HeLa) giving IC50 of 1.6 mu M in visible light (400-700 nm) with low dark toxicity. The photo-induced cell death is via generation of oxidative stress by reactive oxygen species.

Multiple emissive triarylborane-A(2)H(2) and triarylborane-Zn-A(2)H(2) porphyrin conjugates

Triarylborane-A(2)H(2) (1) and triarylborane-Zn-A(2)H(2) porphyrins (2) have been synthesized by acid catalyzed condensation of 4-dimesitylboryl-benzaldehyde and dipyrromethane under ambient conditions. Compounds 1 and 2 showed multiple emission bands upon excitation at the triarylborane dominated absorption region (350 nm). Detailed experimental and computational studies show that the multiple emission features of 1 and 2 arise as a result of a partial energy transfer from the donor (triarylborane) to the acceptor (porphyrin) moieties. Compounds 1 and 2 showed very high selectivities towards fluoride ions compared to other competing anions.

Interpenetrated and Catenated Zinc Thiosulfates Frameworks with dia and qtz Nets: Synthesis, Structure, and Properties

Reactions between Zn(NO3)(2)center dot 6H(2)O, Na2S2O3, 4,4'-bipyridine (bpy), 1,2-bis(4-pyridyl)ethene (bpe), 1,2-bis (4-pyridyl) ethane (bpa), and 1,3-bis(4-pyridyl)propane (bpp) under solvothermal conditions resulted in four new zinc thiosulfate hybrid compounds. Compound I has four-membered zinc thiosulfate rings connected by the ligand, 1,3-bis(4-pyridyl)propane (bpp) forming a two-dimensional structure. Compounds II-IV have one-dimensional zinc thiosulfate chains connected by the ligands, bpy (II), bpe (III), and bpa (IV) giving rise to three-dimensional structures. All the four-structures exhibit 3-fold interpenetration. Proton conductivity studies indicate reasonable proton mobility at 34 degrees C and at 98% relative humidity. The compounds also exhibit Lewis acid character and good photocatalytic activity for the decomposition of cationic dyes.