In vitro evaluation of antibacterial activity of Philippine essential oils in liquid and vapour phase

Bc. Kateřina Hajdu

Diplomová práce

Abstract:

Lower respiratory tract infections belong among the leading causes of death in Philippines. Bacteria responsible for these infections are Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus pyogenes. Due to a limited access to conventional antibiotics in low-income countries and rural regions, locals seek out help in traditional remedies. Traditional medicine uses native plant species most of which have not been previously examined for their antimicrobial activity. Aromatic plants originating from tropical regions contain high amounts of essential oils (EOs). Plant volatiles found in EOs could potentially play important role in inhalation therapy. For that reason, this study aimed to evaluate the antimicrobial activity of EOs obtained from Philippine native trees Calophyllum soulattri, Dipterocarpus grandiflorus, Hopea philippinensis, Hopea plagata, Rubroshorea polysperma, Shorea guiso, Sindora supa, Tristaniopsis decorticata, Vitex parviflora, Xanthostemon bracteatus, and Xanthostemon philippinensis against H. influenzae, S. aureus, S. pneumoniae, and S. pyogenes. Broth microdilution volatilization method was used to test the antimicrobial activity of selected species simultaneously in liquid and vapour phase. C. soulattri performed the highest antimicrobial activity against S. pneumoniae (MIC 256 µg/mL), S. pyogenes (MIC 512 µg/mL), and S. aureus (MIC 1024 µg/mL), followed by D. grandiflorus inhibiting the growth of S. pyogenes (MIC 256 µg/mL) and S. pneumoniae (MIC 512 µg/mL). T. decorticata and X. philippinensis exhibited the same growth-inhibitory effect solely against S. pyogenes (MIC 1024 µg/mL). Interestingly, all of the active EOs tested demonstrated higher efficacy in vapour compared to the liquid phase. Additionally, GC-MS analysis was conducted to establish the chemical profiles of the examined EOs. Majority of all the EOs was constituted out of sesquiterpenes, including α-guaiene, α-himachalene, and cedr-8(15)-en-9-ol. These results indicate the potential for future application of EOs from indigenous plants in inhalation therapy, however subsequent research is necessary.

Keywords

lower respiratory tract infections, antimicrobial activity, broth microdilution volatilization method, Philippines, plant volatiles

Jazyk práce: angličtina

Datum vytvoření / odevzdání či podání práce: 25. 4. 2026

Obhajoba závěrečné práce

• Obhajoba proběhla 1. 6. 2026
• Vedoucí: Ing. Markéta Houdková, Ph.D.
• Oponent: Tomáš Skala, Ph.D.

Česká zemědělská univerzita v Praze

Fakulta tropického zemědělství

Magisterský studijní program:
Tropical Crop Management and Ecology