Solubilization of azo-dye-modified isatin derivative by amphiphilic carboxyresorcinarenes: The effect of macrocycle structure on the supramolecular association

Functionalized Calixarenes as Promising Antibacterial Drugs to Face Antimicrobial Resistance

Since the discovery of polyphenolic resins 150 years ago, the study of polymeric compounds named calix[n]arene has continued to progress, and those skilled in the art perfectly know now how to modulate this phenolic ring. Consequently, calix[n]arenes are now used in a large range of applications and notably in therapeutic fields. In particular, the calix[4]arene exhibits multiple possibilities for regioselective polyfunctionalization on both of its rims and offers researchers the possibility of precisely tuning the geometry of their structures. Thus, in the crucial research of new antibacterial active ingredients, the design of calixarenes finds its place perfectly. This review provides an overview of the work carried out in this aim towards the development of intrinsically active prodrogues or metallic calixarene complexes. Out of all the work of the community, there are some excellent activities emerging that could potentially place these original structures in a very good position for the development of new active ingredients.

Carboxybetaine and Carboxybetaine Ester Derivatives of Tetra(dodecyloxyphenyl)-calix[4]resorcinarene: Synthesis, Self-Assembly and In Vitro Toxicity

Amphiphilic calix[4]resorcinarenes are a class of macrocyclic compounds with broad potential utility including nanomedicine. Here the synthesis of new carboxybetaine and carboxybetaine ester calix[4]resorcinarene bearing 4-(dodecyloxy)phenyl groups on the lower rim is presented. The compounds were characterized by 1H-NMR, 13C-NMR, 2D NMR, IR, ESI and elemental analysis. The critical association concentration values are 1.00 × 10−5 and 1.18 × 10−5 mol·L−1 for carboxybetain and ester, respectively. The hemolytic activity of the macrocycles and their cytotoxicity against normal (WI-38, Chang liver) and tumor cells (M-HeLa) are also estimated.

Calix[4]Resorcinarene Carboxybetaines and Carboxybetaine Esters: Synthesis, Investigation of In Vitro Toxicity, Anti-Platelet Effects, Anticoagulant Activity, and BSA Binding Affinities

As a result of bright complexation properties, easy functionalization and the ability to self-organize in an aqueous solution, amphiphilic supramolecular macrocycles are being actively studied for their application in nanomedicine (drug delivery systems, therapeutic and theranostic agents, and others). In this regard, it is important to study their potential toxic effects. Here, the synthesis of amphiphilic calix[4]resorcinarene carboxybetaines and their esters and the study of a number of their microbiological properties are presented: cytotoxic effect on normal and tumor cells and effect on cellular and non-cellular components of blood (hemotoxicity, anti-platelet effect, and anticoagulant activity). Additionally, the interaction of macrocycles with bovine serum albumin as a model plasma protein is estimated by various methods (fluorescence spectroscopy, synchronous fluorescence spectroscopy, circular dichroic spectroscopy, and dynamic light scattering). The results demonstrate the low toxicity of the macrocycles, their anti-platelet effects at the level of acetylsalicylic acid, and weak anticoagulant activity. The study of BSA-macrocycle interactions demonstrates the dependence on macrocycle hydrophilic/hydrophobic group structure; in the case of carboxybetaines, the formation of complexes prevents self-aggregation of BSA molecules in solution. The present study demonstrates new data on potential drug delivery nanosystems based on amphiphilic calix[4]resorcinarenes for their cytotoxicity and effects on blood components.

Ammonium-Charged Sterically Hindered Phenols with Antioxidant and Selective Anti-Gram-Positive Bacterial Activity

The increase in the resistance of pathogens, in particular Staphylococcus aureus, to the action of antibiotics necessitates the search for new readily available and non-toxic drugs. In solving this problem, phenolic acylhydrazones have high potential. In this communication, the synthesis of quaternary ammonium compounds containing a differently substituted phenolic moiety has been performed. An initial study of antimicrobial activity showed that these compounds are highly selective against S. aureus and B. cereus. The highest activity (MIC 2.0 μm) was shown by hydrazones containing a catechol fragment. These compounds are more than 3-fold more active against S. aureus and 3-10-fold more active against B. cereus than norfloxacin. Low hemolytic and high antioxidant activities of all new compounds were also established.

Calixarenes: Generalities and Their Role in Improving the Solubility, Biocompatibility, Stability, Bioavailability, Detection, and Transport of Biomolecules

The properties and characteristics of calix[n]arenes are described, as well as their capacity to form amphiphilic assemblies by means of the design of synthetic macrocycles with a hydrophilic head and a hydrophobic tail. Their interaction with various substances of interest in pharmacy, engineering, and medicine is also described. In particular, the role of the calix[n]arenes in the detection of dopamine, the design of vesicles and liposomes employed in the manufacture of systems of controlled release drugs used in the treatment of cancer, and their role in improving the solubility of testosterone and anthelmintic drugs and the biocompatibility of biomaterials useful for the manufacture of synthetic organs is emphasized. The versatility of these macrocycles, able to vary in size, shape, functional groups, and hydrophobicity and to recognize various biomolecules and molecules with biological activity without causing cytotoxicity is highlighted.