Work

Terpineol enhances antibiotic effectiveness and reduces resistance in clinically relevant bacteria

Year: 2025

Type: article

Abstract: The synergistic interaction between natural compounds and existing antibiotics (ABXs) offers a promising strategy to enhance ABX efficacy while mitigating resistance. This study evaluated the potential of terpineol (TER), a monocyclic monoterpene of plant origin with antimicrobial properties, as an enhancer of antibiotic activity against 14 clinically and veterinary relevant bacterial strains, including ESKAPE pathogens identified by WHO as urgent targets. The antimicrobial activity of TER and its synergistic effects with 13 commonly used antibiotics were assessed using the checkerboard microdilution method and isobologram representation, with growth kinetics and time-kill curves generated over 24 h. TER showed antimicrobial activity against 14 tested bacteria. The lowest MIC was 0.25 mg/mL for Acinetobacter baumannii (WHO priority 1). TER was effective (MIC = 0.5 mg/mL) against various Gram-negative and positive bacteria, exhibiting bactericidal activity in all cases. TER formed additive and synergistic relationships with 11 antibiotics. Six combinations demonstrated synergy (FICi≤0.5), 24 showed additivity (0.5<FICi≤1), and 13 exhibited indifference (1<FICi<4), with no antagonism (FICi≥4). The six TER/ABX synergies resulted in 100 % inhibition of bacterial growth, reducing MICs by up to 87.5 %. For the first time, this study demonstrated that TER minimally generates microbial resistance compared to commercial antibiotics. Additionally, TER acted as an Antimicrobial Resistance Modifying Agent, reducing resistance to four ABXs (gentamycin, florfenicol, chloramphenicol, tetracycline) in both Gram-positive and negative bacteria. Given its safety profile endorsed by EPA and FDA, TER emerges as a promising candidate for natural antibiotic enhancement, preventing the development of resistance. • Terpineol exhibits bactericidal activity against 14 pathogenic bacteria. • Terpineol has the lowest MIC for Acinetobacter baumannii (WHO priority 1). • Terpineol formed additive and synergistic relationships with 11 common antibiotics. • The six terpineol/antibiotic synergies achieved 100 % bacterial growth inhibition. • The synergies enhanced antimicrobial activity of commercial antibiotics up to 87.5 %.

Source: Heliyon

DOI: 10.1016/j.heliyon.2025.e43932

Authors: Antonio Valenzuela, Cristina Gan, Natalia Ferrando, Elisa Langa, Diego Ballestero, María Rosa Pino-Otín

Institution: Universidad San Jorge

Language: English

Topic: Essential Oils and Antimicrobial Activity

Subfield: Food Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $2,270