DNA sequence-specific ligands. XVII. Synthesis, spectral properties, virological and biochemical studies of fluorescent dimeric bisbenzimidazoles DBA(n)

Recent Advances in Therapeutic Applications of Bisbenzimidazoles

Nitrogen-containing heterocycles are one of the most common structural motifs in approximately 80% of the marketed drugs. Of these, benzimidazoles analogues are known to elicit a wide spectrum of pharmaceutical activities such as anticancer, antibacterial, antiparasitic, antiviral, antifungal as well as chemosensor effect. Based on the benzimidazole core fused heterocyclic compounds, crescent-shaped bisbenzimidazoles were developed which provided an early breakthrough in the sequence-specific DNA recognition. Over the years, a number of functional variations in the bisbenzimidazole core have led to the emergence of their unique properties and established them as versatile ligands against several classes of pathogens. The present review provides an overview of diverse pharmacological activities of the bisbenzimidazole analogues in the past decade with a brief account of its development through the years.

Chemical, Physical and Biological Triggers of Evolutionary Conserved Bcl-xL-Mediated Apoptosis

Background: The evidence that pan-Bcl-2 or Bcl-xL-specific inhibitors prematurely kill virus-infected or RNA/DNA-transfected cells provides rationale for investigating these apoptotic inducers further. We hypothesized that not only invasive RNA or DNA (biological factors) but also DNA/RNA-damaging chemical or physical factors could trigger apoptosis that have been sensitized with pan-Bcl-2 or Bcl-xL-specific agents; Methods: We tested chemical and physical factors plus Bcl-xL-specific inhibitor A-1155463 in cells of various origins and the small roundworms (C. elegans); Results: We show that combination of a A-1155463 along with a DNA-damaging agent, 4-nitroquinoline-1-oxide (4NQO), prematurely kills cells of various origins as well as C. elegans. The synergistic effect is p53-dependent and associated with the release of Bad and Bax from Bcl-xL, which trigger mitochondrial outer membrane permeabilization. Furthermore, we found that combining Bcl-xL-specific inhibitors with various chemical compounds or physical insults also induced cell death; Conclusions: Thus, we were able to identify several biological, chemical and physical triggers of the evolutionarily conserved Bcl-xL-mediated apoptotic pathway, shedding light on strategies and targets for novel drug development.

DNA sequence-specific ligands. XVIII. Synthesis, physico-chemical properties; genetic, virological, and biochemical studies of fluorescent dimeric bisbenzimidazoles DBPA(n)

A set of AT-specific fluorescent dimeric bisbenzimidazoles DBPA(n) with linkers of different lengths bound to DNA in the minor groove were synthesized and their genetic, virological, and biochemical studies were performed. The DBPA(n) were shown to be effective inhibitors of the histon-like protein H-NS, a regulator of the DNA transcription factor, as well as of the Aliivibrio logei Quorum Sensing regulatory system in E. coli cells. Their antiviral activity was tested in model cell lines infected with herpes simplex virus type I. Also, it was found that DBPA(n) could inhibit catalytic activities of HIV-1 integrase at low micromolar concentrations. All of the dimeric bisbenzimidazoles DBPA(n) manifested fluorescent properties, were well soluble in water, nontoxic up to concentrations of 200 µM, and could penetrate into nuclei followed by binding to DNA.

Bioenzymatic and Chemical Derivatization of Renewable Fatty Acids

In addition to our previous efforts toward bioenzymatic and chemical transformations of ricinoleic acid and oleic acid to their corresponding α,ω-dicarboxylic acids via their ester intermediates driven in Escherichia coli cells, several efficient oxidation conditions were investigated and optimized for the conversion of ω-hydroxycarboxylic acids to α,ω-dicarboxylic acids. Pd/C-catalyzed oxidation using NaBH₄ in a basic aqueous alcohol and Ni(II) salt-catalyzed oxidation using aqueous sodium hypochlorite were considered to be excellent as a hybrid reaction for three successive chemical reactions (hydrogenation, hydrolysis, and oxidation) and an eco-friendly, cost-effective, and practical approach, respectively. Omega-hydroxycarboxylic acids and ω-aminocarboxylic acid were also easily prepared as useful building blocks for plastics or bioactive compounds from the bioenzymatically driven ester intermediate. The scope of the developed synthetic methods can be utilized for large-scale synthesis and various derivatizations.