Interaction of the Antibiotic Rifampicin with Lipid Membranes

Area of Science:

• Biophysics
• Pharmacology
• Computational Chemistry

Background:

• Rifampicin is a crucial antibiotic for tuberculosis treatment.
• Its large, complex structure and polar groups challenge typical absorption rules.
• Efficient membrane permeation is key to rifampicin's oral bioavailability, but mechanisms remain unclear.

Purpose of the Study:

• To investigate the interaction of rifampicin with lipid bilayers.
• To elucidate the molecular basis of rifampicin's membrane permeation.
• To compare experimental findings with molecular dynamics simulations.

Main Methods:

• Experimental biophysics techniques.
• Atomistic molecular dynamics (MD) simulations.
• Isothermal titration calorimetry (ITC) and carrageenan leaching assays.

Main Results:

• Both anionic and zwitterionic rifampicin forms interact favorably with POPC lipids.
• The piperazine group deeply inserts into the membrane, stabilizing rifampicin's neutral form.
• Rifampicin perturbs lipid order, reducing membrane barrier properties.

Conclusions:

• Rifampicin's deep membrane insertion and interaction with lipids explain its efficient permeation.
• Molecular features of rifampicin are responsible for its bioavailability.
• Further studies with complex membranes are needed to understand organism-specific interactions.