Distribution of Furamidine Analogues in Tumor Cells:  Influence of the Number of Positive Charges

Abstract

Fluorescence microscopy has been used to study the cellular distribution properties of a series of DNA binding cationic compounds related to the potent antiparasitic drug furamidine (DB75). The compounds tested bear a diphenylfuran or a phenylfuranbenzimidazole unfused aromatic core substituted with one or two amidine or imidazoline groups. The synthesis of five new compounds is reported. The B16 melanoma cell line was used to compare the capacities of mono-, bis-, and tetracations to enter the cell and nuclei. The high-resolution fluorescence pictures show that in the furamidine series, the compounds with two or four positive charges selectively accumulate in the cell nuclei whereas, in most cases, those bearing only one positive charge show reduced cell uptake capacities. One of the monocationic compounds, DB607, distributes in the cytoplasm, possibly in mitochondria, with no distinct nuclear accumulation. In sharp contrast, furamidine and benzimidazole analogues, including the drug DB293 that forms DNA minor groove dimers, efficiently accumulate in the cell nuclei and the intranuclear distribution of these DNA minor groove binders is significantly different from that seen with the DNA intercalating drug propidium iodide. The results suggest that the presence of two amidine terminal groups plays a role in facilitating nuclear accumulation into cells, probably as a result of nucleic acid binding. The determination of DNA melting temperature increases on addition of these compounds supports the importance of DNA binding in nuclear uptake.

Design of DNA Minor Groove Binding Diamidines That Recognize GC Base Pair Sequences: A Dimeric-Hinge Interaction Motif

“…Defining new nucleic acid targets is thus a very promising route for expanding useful drug design approaches. Diamidines have excellent transport properties into a variety of cells [3][4][5][6] and an orally available prodrug of the diamidine, DB75, furamidine (Figure 1), is currently in phase III clinical trials against trypanosomes, which cause sleeping sickness, as well as other microbial parasites. 4,[7][8][9][10][11] DB75 binds strongly in the minor groove of DNA and recognizes sequences of at least four AT base pairs.…”

“…Diamidines have excellent transport properties into a variety of cells [3][4][5][6] and an orally available prodrug of the diamidine, DB75, furamidine (Figure 1), is currently in phase III clinical trials against trypanosomes, which cause sleeping sickness, as well as other microbial parasites. 4,[7][8][9][10][11] DB75 binds strongly in the minor groove of DNA and recognizes sequences of at least four AT base pairs. [7][8][9] For design of new agents that target additional disease organisms/cells as well as evading any possible resistance that could develop, we have focused on modifications of the structure, heterocycles, and properties of the basic units of the DB75 molecule.…”

Synthesis and SAR Study of Novel Amidino 2-substituted Benzimidazoles as Potential Antibacterial Agents

“…[22,33] Furthermore, it was previously shown that positively charged terminal groups are responsible for accumulation into cells. [34,35] Here presented pairs of acyclic and cyclic amidine derivatives have shown almost identical activities against all examined bacterial species. The lipophilic character of compounds has been found to be important parameter for the observed activity of the tested benzoimidazole derivatives against Moraxella catarrhalis.…”

Synthesis, DNA Interactions and Anticancer Evaluation of Novel Diamidine Derivatives of 3,4-Ethylenedioxythiophene

“…32 In general, these molecules should have a minimum two cationic groups to show significant binding and biological activity. Due to the high pK values of the amine moieties and low solubility of the compounds, the number of protons per molecule present in compounds 5a-h and the corresponding pK values could not be determined by standard potentiometric pH titration.…”