# Antibacterial Efficacy of Ethanol Extracts from Edible Rumex madaio Root and Application Potential for Eliminating Staphylococcus aureus and Vibrio cholerae in Aquatic Products for Green Food Preservation

## TL;DR

This study shows that an extract from Rumex madaio root can effectively kill harmful bacteria in seafood while being safe for human cells, making it a promising natural preservative.

## Contribution

The study identifies and characterizes a purified extract from Rumex madaio with potent antibacterial activity and low cytotoxicity for food preservation.

## Key findings

- RmEE-F2 at 1 × MIC inhibited 88.21–91.17% of S. aureus and V. cholerae in stored fish and shrimp.
- RmEE-F2 reduced lipid oxidation and protein degradation in aquatic products during cold storage.
- Transcriptomic analysis showed RmEE-F2 down-regulated bacterial DNA replication and cell wall synthesis.

## Abstract

Edible and medicinal plants provide a treasure trove of natural phytochemicals for mining the next generation of green food preservatives. Herein, we evaluated antibacterial activities of 55–95% ethanol extracts from the edible rhizome of Rumex madaio (RmEEs). The 75% ethanol extract displayed the strongest antibacterial activity, and its purified fraction 2 (RmEE-F2) blocked the proliferation of common pathogens Staphylococcus aureus and Vibrio cholerae, with minimum inhibitory concentrations (MICs) of 391 μg/mL. RmEE-F2 (1 × MIC) altered the bacterial cell surface biophysical parameters and impaired cell structure, resulting in intracellular nucleic acid and protein leakage. It manifested bacteriostatic rates of 88.21–91.17% against S. aureus and V. cholerae in spiked fish (Carassius auratus) and shrimp (Penaeus vannamei) during storage at 4 °C for 24 h. Meanwhile, RmEE-F2 effectively rendered the pH rising and reduced lipid oxidation and protein degradation of C. auratus and P. vannamei meat samples at 4 °C for 6 days. Additionally, RmEE-F2 (< 781 µg/mL) showed non-cytotoxicity to human colon Caco-2, liver HepG-2, and lung A549 cell lines, and rescued V. cholerae and S. aureus-infected Caco-2 cellcells with enhanced viability of 14.31–16.60% (1 × MIC). Comparative transcriptomic analysis revealed down-regulated protein synthesis, cell wall and cell membrane synthesis, and or DNA replication and repair in the tested bacteria triggered by RmEE-F2. The major antibacterial compounds in RmEE-F2 included melibiose (9.86%), 3-(N, N-dimethylaminomethyl) indole (7.12%), and citric acid (6.07%). Overall, this study underscores the promising potential of RmEE-F2 for aquatic product green preservation.