Pectis brevipedunculata (Gardner) Sch.Bip., known in Brazil as alecrim do campo, is a small Asteraceae family plant with a calming effect and consumed as tea. This species contains components, such as neral and geranial, that display various biological activities, such as leishmanicidal. The aim was to chemically characterize the essential oil (EO) obtained from P. brevipedunculata (EO-PB) by hydrodistillation and a microemulsion formulated with EO (ME-PB), Tween 80 and Transcutol P, assess the leishmanicidal effect against Leishmania (L.) amazonensis promastigotes and cytotoxicity against RAW 264.7. EO-PB and ME-PB were analyzed by Gas Chromatography Mass Spectrometry (GC/MS). Monoterpene hydrocarbons were noteworthy among the identified compounds. The main EO-PB constituents were α-pinene and limonene, followed by neral and geranial, which were maintained in ME-PB. EO-PB presented an inhibitory concentration (IC₅₀) of 20 µg/mL and ME-PB of 0.93 µg/mL. ME-PB inhibition towards the parasite was 20-fold higher than that of EO-PB. This indicated that EO incorporation to the microemulsion resulted in optimized biological activity. Selectivity indices indicate that ME-PB is more selective concerning parasite inhibition. Thus, ME-PB may comprise an adequate approach against Leishmania, as the inhibitory concentration (IC₅₀) promastigotes was lower than that considered toxic for cells cell cytotoxicity of 50% (CC₅₀).

Pectis brevipedunculata, commonly known as field rosemary, belongs to the Asteraceae family. This species’ leaves contain citral among their major compounds, a chemical marker of their essential oils (EO), among their major compounds. EO from Pectis species, which has antimicrobial, nematicidal, and larvicidal effects. The species is widely distributed throughout Brazil and, although it is popularly used in the form of tea, it has no significant use. This study aimed to obtain essential oil (EO) from the aerial parts of P. brevipedunculata (EO-PB), develop a microemulsion (ME) for incorporating the EO (ME-PB), and evaluate its antimicrobial potential when applied to strawberries. Chemical characterization by GC/MS of the hydrodistilled essential oil (EO) revealed that its main EO components were α-pinene (56.47%), limonene (19.98%), neral (3.78%), and geranial (3.46%). Analysis of the ME by GC/MS-Headspace and infrared spectroscopy confirmed the incorporation of the EO into the formulation. Physical-chemical characterization showed that the particle size, polydispersity index and zeta potential were consistent with published data. Regarding antimicrobial potential, the ME-PB formulation exhibited inhibition halos exceeding 50.00 mm against all tested bacteria (Escherichia coli (ATCC 25922), Salmonella spp. (ATCC 14028), Listeria monocytogenes (ATCC 35152), Staphylococcus aureus (ATCC 25923), Bacillus cereus (ATCC 14579) and Clostridium spp.). Notably, the inhibition halos were larger compared to those of the antibiotics penicillin and gentamicin. In contrast, EO-PB exhibited smaller inhibition halos for all the tested bacteria, except for S. aureus. It is noteworthy that antibiotics and essential oils exhibit different diffusion behaviors in agar. ME-PB indicated minimum inhibitory concentration values lower than those obtained by the action of the EO, and was considered to have strong inhibitory properties against all the bacteria tested. When EO and ME were applied to strawberries, it was found that EO-PB and ME-PB were effective against mesophilic aerobes and fungi, inhibiting the proliferation of microorganisms and extending the shelf life of strawberries. The results demonstrate the species’ potential and show that incorporating EO into ME optimizes the bioavailability of bioactive principles and improves biological activity.