# Glycyrrhiza glabra L. Saponins Modulate the Biophysical Properties of Bacterial Model Membranes and Affect Their Interactions with Tobramycin

## TL;DR

This study shows that saponins from licorice root can change bacterial membranes, potentially boosting antibiotic effectiveness.

## Contribution

The novel contribution is demonstrating how saponins from Glycyrrhiza glabra alter bacterial membrane properties to enhance antibiotic interactions.

## Key findings

- GgC saponins reduce membrane compressibility modulus by 25-50% at 1.25-10 mg/L.
- Saponins modify membrane surface charge without causing lysis.
- These changes may improve antibiotic interactions with bacterial cells.

## Abstract

The global challenge of antibiotic resistance necessitates
innovative
approaches to improving the efficacy of existing therapeutics while
mitigating their environmental impact. This study investigates the
role of saponins derived from Glycyrrhiza glabra root extract in modulating interactions of tobramycin, a broad-spectrum
aminoglycoside antibiotic, with model bacterial membranes composed
of phosphatidylglycerol. Using Langmuir monolayers and vesicle models,
we demonstrated that GgC saponins disrupt lipid packing, increasing
membrane fluidity and altering biophysical properties. The addition
of saponins at concentrations between 1.25 and 10 mg/L reduces the
compressibility modulus of the lipid monolayer, with a decrease ranging
from 25 to over 50%. ζ potential and dynamic light scattering
analyses indicated that GgC–tobramycin interactions modify
the surface charge without causing membrane lysis. These membrane
changes could potentially facilitate enhanced interactions of antibiotics
with bacterial cells. Importantly, these findings suggest the potential
of natural surfactants such as saponins to improve antibiotic efficacy,
possibly enabling reduced antibiotic dosages. This study provides
insights into using saponins alongside antibiotics as a sustainable
approach to addressing antibiotic resistance.