# GNPS Untargeted GC‐MS Metabolomic Analysis of Essential Oils From Duguetia lanceolata and Evaluation of Antimicrobial Activity

## TL;DR

This study analyzed essential oils from Duguetia lanceolata leaves collected in different seasons and found they have different chemical compositions and antimicrobial properties.

## Contribution

The study introduces a GNPS untargeted GC-MS approach to compare seasonal variations in essential oil composition and antimicrobial activity of Duguetia lanceolata.

## Key findings

- Autumn essential oils contained monoterpenes like limonene, while winter oils were rich in sesquiterpenes like β-bisabolene.
- Autumn essential oils showed stronger antimicrobial activity against bacteria and yeast compared to winter oils.
- Molecular docking suggested that limonene and β-bisabolene bind to key enzymes in bacteria and fungi, explaining their antimicrobial effects.

## Abstract

In this study, the chemical composition of essential oils (EOs) extracted from leaves of Duguetia lanceolata collected in different seasons (autumn and winter) was analyzed using a GNPS untargeted GC‐MS metabolomic approach. EO from autumn leaves (EO‐A) contained 80 metabolites (93.8%), with limonene (28.5%), (+)‐β‐pinene (15.0%), cyclocolorenone (12.8%), 6,9‐guaiadiene (3.1%), and 4‐carvomenthenol (3.1%) as major constituents. EO from winter leaves (EO‐W) comprised 102 compounds (88.0%), dominated by β‐bisabolene (16.4%), β‐gurjunene (6.4%), β‐caryophyllene (4.7%), cyclocolorenone (3.9%), and dihydrocarveol (3.3%). The antimicrobial activity of both EOs was evaluated in vitro using the disk diffusion method against gram‐positive and gram‐negative bacteria, as well as selected yeast strains. MIC values ranged from 0.016 to 0.270 µg·mL−
1, with EO‐A generally exhibiting lower MICs than EO‐W. EO‐A was active against Acinetobacter baumannii, Candida krusei, and Candida parapsilosis, whereas EO‐W showed no activity against these strains. Complementary in silico analyses supported these findings: PASS predictions suggested potential antibacterial and antifungal activity for the major constituents, and molecular docking indicated favorable binding of limonene and β‐bisabolene to DNA gyrase B (A. baumannii) and lanosterol 14α‐demethylase (CYP51, C. albicans), providing a mechanistic rationale for the observed antimicrobial effects. These results highlight the importance of seasonal collection in optimizing the bioactive potential of D. lanceolata leaves.

Untargeted metabolomic analysis of the essential oil of D. lanceolata leaves collected in winter revealed that they are mostly composed of sesquiterpenes, while those collected in autumn showed a predominance of monoterpenes. Both essential oils displayed antimicrobial activity against bacterial and fungal species. All graphical elements were created using BioRender.com.