Modulation of strain-selective antimicrobial activity by the supramolecular ensemble of a pillar[5]arene with a...

Self-assembling macrocycles capable of modulating biomolecular interactions represent promising platforms for the development of supramolecular bioactive systems. Herein, water-soluble pillar[5]arene derivatives bearing L-Asp, L-Glu, and sulfonamide fragments were synthesized and investigated as modulators of cysteine proteases and antibacterial agents. The sulfonamide-containing macrocycle formed stable self-assembled structures with a mean hydrodynamic diameter of 144 ± 5 nm (ζ = 52 ± 2 mV). In contrast, papain and bromelain exhibited nonspecific aggregation, forming particles of 400-458 nm (PDI 0.37-0.44). Interaction with the macrocycle induced a size-controlled reorganization of protease aggregates into stable supramolecular assemblies with diameters of 253-258 nm and PDI values of 0.23-0.28. Spectroscopic studies revealed moderate binding affinities (lgK_a = 3.95-4.15), while in silico modelling indicated recognition of the conserved V-shaped active-site cleft of the proteases. The sulfonamide-containing pillar[5]arene also displayed antibacterial activity against all tested strains, with MIC values of 62.5-250 μM. Notably, protease binding resulted in strain- and protease-dependent modulation of antibacterial activity. For the sulfonamide-containing pillar[5]arene + bromelain system, MIC values of 75 ± 6 μM against S. aureus and 150 ± 11 μM against E. faecalis were observed. These findings demonstrate that preorganized self-assembling pillar[5]arenes can regulate protein supramolecular organization and bioactivity, providing a promising platform for tunable supramolecular modulation of biomolecular interactions.