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PP-02

Antibacterial activity of herbal extracts against Acinetobacter baumannii

1
,2
Chih-Yen Chen, Hsien-Ming Lee*

1 Graduate Institute of Medical Laboratory Science and Biotechnology, Central Taiwan
University of Science and Technology, Taichung 406053, Taiwan
2 Department of Optometry, Central Taiwan University of Science and Technology, Taichung
406053, Taiwan
* E-mail: hmlee@ctust.edu.tw

Abstract
Acinetobacter baumannii is a Gram-negative bacterium that has become well-known in
recent years as a highly multidrug-resistant (MDR) pathogen, posing a serious challenge to
clinical treatment. With growing concerns over antibiotic resistance, natural herbal medicines
have been explored as potential alternatives due to their diverse origins, multiple mechanisms
of action, and lower risk of inducing resistance. This study aimed to evaluate the antibacterial
activity of five dried herbal extracts (Polygonum cuspidatum, Polygonum chinense,
Rhinacanthus nasutus, Houttuynia cordata, and Taraxacum officinale) against A. baumannii.
The herbs were extracted by five different solvents (methanol, ethanol, hexane, chloroform, and
ethyl acetate), and antibacterial efficacy was determined using the disc diffusion method. The
results showed that methanol and ethanol extracts of Polygonum chinense exhibited inhibitory
activity against A. baumannii BCRC15884 and BCRC10591 (8–11 mm). It also demonstrated
antibacterial activity against two other Gram-negative bacteria (Escherichia coli and
Pseudomonas aeruginosa) and Staphylococcus aureus (8–11 mm). In contrast, P. cuspidatum
was only effective against S. aureus (24–33 mm) ; H. cordata showed inhibition only against P.
aeruginosa (12 mm); and T. officinale exhibited moderate activity against S. aureus and E. coli
(7–11 mm). Rhinacanthus nasutus did not show any antibacterial effects. These findings
suggest that P. chinense may be a promising natural candidate for treating MDR A. baumannii.
Future research will focus on the isolation and identification of its active antimicrobial
compounds.

Keywords: Herbal medicines; Polygonum chinense; Acinetobacter baumannii