# Alpha-linolenic acid-modified liposomes associate with and modulate antibiotic activity against Helicobacter pylori

## TL;DR

This study shows that adding alpha-linolenic acid to liposomes improves their ability to target and kill Helicobacter pylori bacteria when combined with amoxicillin.

## Contribution

The first demonstration that alpha-linolenic acid in liposomes enhances both targeting and antibiotic efficacy against H. pylori.

## Key findings

- Liposomes with alpha-linolenic acid and amoxicillin achieved a 3-log reduction in H. pylori density.
- Alpha-linolenic acid-modified liposomes bound to H. pylori more effectively than non-modified liposomes.
- The combination of alpha-linolenic acid and amoxicillin in liposomes showed greater antibacterial activity than either alone.

## Abstract

Summary of key findings: (1) Linolenic acid (αLA) was effective in killing Helicobacter pylori, but not Escherichia coli or Campylobacter jejuni. (2) Liposomes encapsulating αLA and amoxicillin had greatly enhanced bactericidal activity against H. pylori, compared to liposomes containing just one of these components, or amoxicillin in solution. (3) Liposomes encapsulating αLA rapidly bound to H. pylori at higher densities compared to liposomes without αLA. Created in BioRender. Robinson, K. (2025) a31l841 https://BioRender.com.

Fatty acids have antimicrobial activity against a wide range of bacteria. We therefore aimed to incorporate omega-3 unsaturated alpha-linolenic acid (αLA) into the membrane of antibiotic-loaded liposomes to create a system with dual antibacterial activity against Helicobacter pylori. Liposomes containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, cholesterol, sphingomyelin and the far-red fluorescent DiD label, with varying content of αLA (mol% to total lipid), were fabricated using the thin film evaporation method and hydrated with PBS or amoxicillin solution. The liposomes were characterized for αLA and amoxicillin content, particle size, membrane fluidity and permeability, prior to their addition to cultures of H. pylori strains and clinical isolates. αLA-modified liposomes enhanced the antibacterial action of amoxicillin against H. pylori, as determined using a viable count method. The liposomal formulation achieved a 3-log reduction in bacterial density, compared to a 1.5- to 2-log reduction by amoxicillin in solution. The application of imaging cytometry revealed a significantly increased association of αLA-modified liposomes with H. pylori cells, compared to non-αLA control liposomes. In conclusion, this study demonstrated, for the first time, that the incorporation of αLA increased the attraction of the liposomes to H. pylori and increased antibiotic potency. This suggests that αLA incorporation into liposomes may not only act as an antimicrobial, but also as a potential in vivo targeting strategy.