The hydrophobic core effect in model bacterial membranes upon interaction with tetra-p-guanidinoethylcalix[4]arene

The calixarene derivative used in this study (tetra-p-guanidinoethylcalix[4]arene) shows in vitro activity against different Gram-positive and Gram-negative bacteria. The interaction between bacterial cell membranes and the water-soluble calixarene was investigated using model lipids spread as monomolecular films at the air-water interface. Compression and adsorption experiments, as well as Brewster angle microscopy, polarization modulation-infrared reflection-absorption spectroscopy and computer modeling permitted understanding of the intra- and intermolecular interaction in several lipid-calixarene systems. Because the affinity of the calixarene derivative for the membranes may be linked to the interaction with negative charges, phosphatidylglycerols were used as model lipids; the phosphatidylglycerols contained saturated or unsaturated hydrocarbon chains with different lengths. It was showed that the affinity of the calixarene for the monolayer depends on the structure of the phosphatidylglycerols side chains. This observation may be of interest for a further development of new antibiotics. (C) 2021 The Authors. Published by Elsevier B.V.