New peptide conjugates with 9-aminoacridine: synthesis and binding to DNA

Acidobasic equilibria of inubosin derivatives studied by UV-Vis spectroscopy

Inubosin derivatives were suggested as compounds supporting the regeneration of neurons. For practical pharmaceutical applications their physicochemical properties need to be optimized in terms of bioavailability, possible side effects, and efficiency. We focused on four inubosin B derivatives, where acidobasic constants as key players in the biological activity were determined using the UV-Vis spectroscopy. The constants were correlated with the structure on the basis of the Hammett theory. In addition, water-organic solvent equilibria were studied for selected compounds. A software for semi-automated processing of the UV-Vis titration data was developed and tested. Time dependent density functional theory (TDDFT) was used to model and interpret the experimental spectra, which made it possible, for example, to assign the most characteristic cationic band to the S0 → S2 transition. For the acridine acid, both the TDDFT computations and the experimental data indicate that it forms zwitterion in the aqueous solution, whereas it is not dissociated in the organic phase.

Preparation and characterization of Gum Arabic Schiff's bases based on 9-aminoacridine with in vitro evaluation of their antimicrobial and antitumor potentiality

The conjugation between drug and biopolymers through an easily hydrolysable bond such as ester linkage, disulfide linkage, or imine-bond have been extensively employed to control the drug release pattern and improve its bioavailability. This work described the conjugation of 9-aminoacridine (9-AA) to Gum Arabic (GA) via Schiff's base, as a pH-responsive bond. First, GA was oxidized to Arabic Gum dialdehyde (AGDA), then a different amount of 9-AA (10, 25, and 50 mg 9-AA) was coupled to defined amount of AGDA, the coupling was confirmed by elemental analysis and different spectroscopic tools. In addition, the physical features of Schiff's base conjugates including surface morphology, thermal stability, and crystalline structure were examined. The thermogravimetric analysis revealed that the incorporation of 9-AA slightly improved the thermal stability. The coupling of 9-AA to AGDA dramatically enhanced its in vitro antimicrobial and antitumor activities. All conjugates exhibited broad-spectrum activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, and Candida albicans. Moreover, AGA 25 and AGA 50 demonstrated promising capability to suppress the proliferation of human colon cancer cell line (Caco-2), with IC₅₀ 190.10 and 180.80 μg/mL respectively.

Efficient and Short Method for Conjugation of 1-Nitro-9-Aminoacridine to Important Peptidyl Fragments by a Solid Support Synthesis

The efficient and short techniques for conjugation of 9-aminoacridine with different peptidyl fragments are necessary for the development of active pharmaceutical ingredients (API). They need to be adopted to generate a new branch of acridine conjugates, enhancing their bioavailability for the examination in biological systems. The branch of developing acridine conjugates, built via different linkers and synthesized in this study, are expected as potential effective chemotherapeutics with dual mechanism of action. Recently, the methodology based on a solid-phase technique has been successfully demonstrated in preparing a number of promising compounds. However, the reaction conditions for amide bond formation between 1-nitro-9-aminoacridine and peptidyl fragments need to be optimized. In this study, the optimization of amide bond formation was demonstrated with the use of the solid-phase synthesis to build a new promising group of 1-nitro-9-aminoacridines conjugated to lactoferrin fragments via especially carboxy linker length.

Amino acid or peptide conjugates of acridine/acridone and quinoline/quinolone-containing drugs. A critical examination of their clinical effectiveness within a twenty-year timeframe in antitumor chemotherapy and treatment of infectious diseases

Acridines/acridones, quinolines/quinolones (chromophores) and their derivatives constitute extremely important family of compounds in current medicine. Great significance of the compounds is connected with antimicrobial and antitumor activities. Combining these features together in one drug seems to be long-term benefit, especially in oncology therapy. The attractiveness of the chromophore drugs is still enhanced by elimination their toxicity and improvement not only selectivity, specificity but also bioavailability. The best results are reached by conjugation to natural peptides. This paper highlights significant advance in the study of amino acid or peptide chromophore conjugates that provide highly encouraging data for novel drug development. The structures and clinical significance of amino acid or peptide chromophore conjugates are widely discussed.

Enhanced drug toxicity by conjugation of platinum drugs to polymers with guanidine containing zwitterionic functional groups that mimic cell-penetrating peptides

Inspired by the Ringsdorf model, statistical copolymers with solubility enhancers, platinum drugs and groove binders were compared.

DFT Description of Intermolecular Forces between 9-Aminoacridines and DNA Base Pairs

The B3LYP method with 6-31G* basis set was used to predict the geometries of five 9-aminoacridines (9-AA 1(a–e)), DNA base pairs, and respective complexes. Polarizabilities, charge distribution, frontier molecular orbital (FMO), and dipole moments were used to analyze the nature of interactions that allow reasonable drug diffusion levels. The results showed that charge delocalization, high polarizabilities, and high dipole moments play an important role in intermolecular interactions with DNA. The interactions of 9-AA 1(a–e) with GC are the strongest. 9-AA 1(d) displayed the strongest interaction and 9-AA 1(b) the weakest.

A kinetic and structural investigation of DNA-based asymmetric catalysis using first-generation ligands

The recently developed concept of DNA-based asymmetric catalysis involves the transfer of chirality from the DNA double helix in reactions using a noncovalently bound catalyst. To date, two generations of DNA-based catalysts have been reported that differ in the design of the ligand for the metal. Herein we present a study of the first generation of DNA-based catalysts, which contain ligands comprising a metal-binding domain linked through a spacer to a 9-aminoacridine moiety. Particular emphasis has been placed on determining the effect of DNA on the structure of the Cu(II) complex and the catalyzed Diels-Alder reaction. The most important findings are that the role of DNA is limited to being a chiral scaffold; no rate acceleration was observed in the presence of DNA. Furthermore, the optimal DNA sequence for obtaining high enantioselectivities proved to contain alternating GC nucleotides. Finally, DNA has been shown to interact with the Cu(II) complex to give a chiral structure. Comparison with the second generation of DNA-based catalysts, which bear bipyridine-type ligands, revealed marked differences, which are believed to be related to the DNA microenvironment in which the catalyst resides and where the reaction takes place.