# Phytochemical Composition and In Vitro Antibacterial Activity of the Essential Oil from Lippia grata Schauer (Verbenaceae) against Staphylococcus spp. from Caprine Mastitis

## TL;DR

This study shows that essential oil from Lippia grata can fight bacteria causing goat mastitis, including those that form protective biofilms.

## Contribution

The study demonstrates the antibacterial and antibiofilm potential of Lippia grata essential oil against Staphylococcus spp. from caprine mastitis.

## Key findings

- The essential oil of L. grata contains carvacrol as the main component and inhibits Staphylococcus spp. at concentrations of 256–512 μg/mL.
- The oil reduced biofilm formation in some isolates and disrupted pre-established biofilms in all tested isolates.
- L. grata essential oil shows promise as a treatment for caprine mastitis caused by biofilm-forming bacteria.

## Abstract

Staphylococcus spp. are
the primary
pathogens responsible for caprine mastitis. These bacteria can form
biofilms, hindering treatment and compromising milk production. In
this context, plant-based natural products derived from Lippia grata Schauer have emerged as a potential
alternative for treatment. This study aimed to evaluate the antibacterial
and antibiofilm properties of the essential oil (EO) of L. grata against Staphylococcus spp. isolated from caprine mastitis. The EO was obtained by hydrodistillation,
and its chemical constituents were identified by gas chromatography
coupled with mass spectrometry. Fourteen clinical isolates of Staphylococcus spp. and two standard strains were
tested. Antibacterial activity was assessed using broth microdilution.
Biofilm production and the interference capacity of the EO were evaluated
using a microplate adherence assay. The EO of L. grata yielded 5.47%, with carvacrol (78%), thymol (7.1%), and p-cymene (3.16%) as the main constituents. It exhibited
inhibitory and bactericidal effects at concentrations ranging from
256 to 512 μg mL–1. All isolates formed biofilms,
and the EO reduced biofilm formation in two isolates classified as
moderate and strong producers. Additionally, it disrupted pre-established
biofilms in all isolates. Therefore, the EO of L. grata exhibits antimicrobial and antibiofilm activities and represents
a promising alternative for treating caprine mastitis, particularly
in infections involving biofilm formation.